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Global pollinator declines: Trends, impacts and drivers
Abstract
Pollinators are a key component of global biodiversity, providing vital ecosystem services to crops and wild plants. There is clear evidence of recent declines in both wild and domesticated pollinators, and parallel declines in the plants that rely upon them. Here we describe the nature and extent of reported declines, and review the potential drivers of pollinator loss, including habitat loss and fragmentation, agrochemicals, pathogens, alien species, climate change and the interactions between them. Pollinator declines can result in loss of pollination services which have important negative ecological and economic impacts that could significantly affect the maintenance of wild plant diversity, wider ecosystem stability, crop production, food security and human welfare.
... Studies exploring the impacts of anthropization on plant-pollinator interaction networks have been pivotal in our understanding of how human activities have fundamentally altered these vital ecological relationships (e.g., Potts et al., 2010;Burkle, Marlin & Knight, 2013;White, Collier & Stout, 2022;Pardee et al., 2023). The focus of these investigations primarily centers on discerning the shifts in structural patterns within these networks. ...
... Overall, land conversion activities can affect richness and abundance of both plant and pollinator species in several ways (Potts et al., 2010). For example, urbanization often leads to the loss and fragmentation of natural habitats, resulting in reduced floral resources and nesting sites for pollinators (Hall et al., 2017). ...
... Based on the observed trends in the reviewed literature, we expect that networks from conserved environments would harbor greater richness and diversity of pollinators and plants compared to anthropized environments. Previous studies have shown that habitat conservation is associated with higher abundance (Díaz & Cabido, 2001;Winfree, Bartomeus & Cariveau, 2011) and species diversity (Potts et al., 2010;Hall et al., 2017). Furthermore, we expect that interaction networks between pollinators and plants in anthropic environments would exhibit a decrease on levels of nestedness and modularity, and they should be less specialized (Tylianakis et al., 2008;Bascompte & Jordano, 2013). ...
Background
Anthropogenic activities significantly impact natural ecosystems, leading to alterations in plant and pollinator diversity and abundance. These changes often result in shifts within interacting communities, potentially reshaping the structure of plant-pollinator interaction networks. Given the escalating human footprint on habitats, evaluating the response of these networks to anthropization is critical for devising effective conservation and management strategies.
Methods
We conducted a comprehensive review of the plant-pollinator network literature to assess the impact of anthropization on network structure. We assessed network metrics such as nestedness measure based on overlap and decreasing fills (NODF), network specialization (H 2 ’), connectance (C), and modularity (Q) to understand structural changes. Employing a meta-analytical approach, we examined how anthropization activities, such as deforestation, urbanization, habitat fragmentation, agriculture, intentional fires and livestock farming, affect both plant and pollinator richness.
Results
We generated a dataset for various metrics of network structure and 36 effect sizes for the meta-analysis, from 38 articles published between 2010 and 2023. Studies assessing the impact of agriculture and fragmentation were well-represented, comprising 68.4% of all studies, with networks involving interacting insects being the most studied taxa. Agriculture and fragmentation reduce nestedness and increase specialization in plant-pollinator networks, while modularity and connectance are mostly not affected. Although our meta-analysis suggests that anthropization decreases richness for both plants and pollinators, there was substantial heterogeneity in this regard among the evaluated studies. The meta-regression analyses helped us determine that the habitat fragment size where the studies were conducted was the primary variable contributing to such heterogeneity.
Conclusions
The analysis of human impacts on plant-pollinator networks showed varied effects worldwide. Responses differed among network metrics, signaling nuanced impacts on structure. Activities like agriculture and fragmentation significantly changed ecosystems, reducing species richness in both pollinators and plants, highlighting network vulnerability. Regional differences stressed the need for tailored conservation. Despite insights, more research is crucial for a complete understanding of these ecological relationships.
... Pollinators, especially some bees and butterflies, are declining precipitously (Wagner 2020;Potts et al. 2010;Cameron et al. 2011;Abrol 2012;Goulson & Nicholls 2016;Rhodes 2018;Wagner 2020), and their decline will likely decrease the production of viable seeds because less pollen may be transported by pollinators (Potts et al. 2010). Rare plants that rely on specialist pollinators may be especially vulnerable to declining pollinators; however, many rare plants use common pollinators (Bascompte et al. 2003;Vázquez and Aizen 2004;Rasmussen et al. 2020). ...
... Pollinators, especially some bees and butterflies, are declining precipitously (Wagner 2020;Potts et al. 2010;Cameron et al. 2011;Abrol 2012;Goulson & Nicholls 2016;Rhodes 2018;Wagner 2020), and their decline will likely decrease the production of viable seeds because less pollen may be transported by pollinators (Potts et al. 2010). Rare plants that rely on specialist pollinators may be especially vulnerable to declining pollinators; however, many rare plants use common pollinators (Bascompte et al. 2003;Vázquez and Aizen 2004;Rasmussen et al. 2020). ...
The reproductive ecology of rare plants is often unknown, yet the persistence of most plant populations depends on successful interactions with pollinators and favourable environmental conditions. Sexual reproduction maintains genetic diversity within plant populations using pollinators to transport pollen grains among plants of the same species and producing seeds. We investigated the reproduction of Yermo xanthocephalus Dorn (Desert yellowhead), a perennial member of Asteraceae endemic to central Wyoming, USA, which grows in only two locations within 8 km of each other. Our objectives were to assess the pollination and seed-set of Y. xanthocephalus. We conducted seed-set experiments in both populations to measure self-pollination and estimate if pollinating insects limited seed production. We used vane traps and pan traps to capture pollinators, and we examined pollen carried on bees. Yermo xanthocephalus can self-pollinate, but seed-set was extremely low. The number of viable seeds produced in flowerheads pollinated by insects did not differ from those produced by capitula hand-pollinated with excess pollen, indicating that pollinators did not limit seed production that year. Pollen from Y. xanthocephalus was carried by nine bee genera, suggesting that no one specific insect pollinates this plant. Only 12% of ovules produced viable seeds in the main population and 0% were viable in the other population, suggesting that something beyond pollinators limited seed-set. We recommend continued research to address what is limiting seed production to advance the knowledge and management of this declining plant species.
... Während manche Nutzpflanzen wie Kartoffeln oder Getreide selbst-oder windbestäubt sind, hängen über 75% der meistproduzierten Anbau-und 87,5% der Wildpflanzen von der Bestäubung durch Insekten ab (Kleijn et al. 2015;Ollertonet al. 2011;Ricketts et al. 2008). Die Bestäubung gehört daher zu den essenziellen Ökosystemdienstleistungen und leistete z.B. im Jahr 2005 mit mehr als 153 Milliarden Euro einen enormen Beitrag zur Weltwirtschaft und zur Sicherung der Ernährung der Menschheit (Gallai et al., 2009;Potts et al., 2010). ...
... Die Bestäubung als Ökosystemleistung gilt, verursacht durch den Rückgang von bestäubenden Insekten, jedoch seit mehreren Jahren als gefährdet (Potts et al. 2010). Hauptverursacher für diesen Verlust sind im Wesentlichen die Intensivierung der Landwirtschaft und der damit verbundene erhöhte Einsatz von Pflanzenschutzmitteln und der Rückgang an Blütenpflanzen. ...
Insect pollination is one of the most important ecosystem services provided to humans. Over 75% of crops and 87,5% of wild plants are directly dependend from this type of pollination. The two biggest insect pollination groups in German agroecosystems are the Brachycera ("true flies") and Hymenoptera. However, a decline trend in agricultural biodiversity has been observed in the past years, which is why the need for sustainable conservation strategies for pollination services is more needed than ever before. Therefore, via DNA-Barcoding the potential pollinators of caraway (Carum carvi) will be identified. Additionally, other plants that might be important in the pollination network of caraway will be identified via Metabarcoding pollen samples. Therefore, Hymenoptera and Brachycera samples were collected during the vegetations periods of 2016 and 2017 on two areas (one with and one without flowering strips) with a hand net on three different day intervals. Overall, on 14 sampling days of each year pollinators were collected, and in 2016 in total 1055 specimens were compiled. First preliminary results of morphological and genetic analysis suggest that around 54 fly and 43 Hymenoptera species are present in the caraway before, during and after the blooming. Further aims are to combine these results with the one of the metabacoding, build up the pollinator network of caraway, and based on this information generate future recommendations for a sustainable management of pollination services.
... Hormigas (Hymemoptera: Formicidae), abejas (Hymenoptera: Apidae) y arañas (Araneae) son grupos de artrópodos altamente diversos, numéricamente dominantes en la mayoría de los ecosistemas terrestres, que brindan importantes servicios ecosistémicos (Del Toro et al., 2012;Michalko et al., 2019;Underwood & Quinn, 2010) y son altamente sensibles a los cambios ambientales (Buchholz, 2010;Churchill, 1997;Potts et al., 2010;Tiede et al., 2017). Todas estas características citadas, convierte a hormigas, arañas y abejas en excelentes taxones indicadores para monitorear las respuestas de la biodiversidad de artrópodos frente a cambios ambientales (Andersen et al., 2004;Gollan et al., 2011;Pearce & Venier, 2006;Williams et al., 2010). ...
... Existen estudios que muestran que las hormigas contribuyen significativamente a la dispersión de frutos y semillas de numerosas plantas herbáceas y arbustivas en la península ibérica (Barroso et al., 2013;Boulay et al., 2007;Retana et al., 2004) y, además, pueden ser claves en la recuperación de la vegetación después del incendio (Arnan et al., 2010. Por otro lado, el papel de las abejas como eficientes polinizadores de los ecosistemas es bien conocido, proporcionando un servicio ecosistémico esencial para el mantenimiento de la diversidad de las plantas silvestres (Aguilar et al., 2006;Potts et al., 2016Potts et al., , 2010 (Figura 3 a y b). Por último, entre los artrópodos existentes, las arañas son los depredadores por excelencia (Turnbull, 1973) y cambios en su diversidad taxonómica y funcional pueden alterar la composición, la diversidad y la dinámica de la población de los niveles tróficos inferiores (Bruno & Cardinale, 2008;Prieto-Benítez and Méndez, 2011). ...
Forest fires are one of the most frequent disturbances in Mediterranean environments. They greatly alter forest ecosystems, modifying the structure and composition of plant communities which consequently affects the structure and composition of the animal communities that inhabit them.
The general objective of this Doctoral Thesis is to investigate the short-, medium- and long-term response three groups of arthropods have to fire in coniferous systems in Mediterranean environments of the Iberian Peninsula. We studied the structure and composition of the communities of ants, bees and spiders affected by fire from a taxonomic and functional point of view. We also measured how fire affects the hierarchy of dominance in ant communities. For this purpose, field sampling was carried out using pitfall traps, Moericke traps and baits in pine forests of the Iberian Peninsula affected by forest fires that occurred varying periods of time.
Fire had a more pronounced effect on the communities of ants than in did on those of bees and spiders. The taxonomic response of ants (abundance, richness and diversity) varied highly. These variables decreased in the short-term in one case, recovered in the short-term in another case, and they even increased, independently of the time elapsed after the fire. At the functional level, the ant communities in burned areas are predominantly composed of thermophilic and subordinate species, and also of dominant species in more open habitats. In unburned areas, however, the species tend to be less thermophilic and are associated with more developed vegetation, especially the tree layer and tall shrubs. Therefore, fire may act as a niche filtering mechanism, with a long-term effect on some functional traits and a short-term effect on other ones.
In conclusion, fire alters arthropod communities at the taxonomic and functional level, especially in ants. Taxonomic alterations are variable and depend more on the local scale (the recovery of the vegetation and the types of ant community present before the fire), while functional alterations are longer-term and more predictable.
... Insects that visit flowers are critical for the functioning of many ecosystems, playing a vital role in the maintenance of biodiversity and the provision of pollination ecosystem services (Gallai et al., 2009;Klein et al., 2007;Porto et al., 2020). Yet, many pollinators are endangered due to human-induced global-change drivers (Goulson et al., 2015;Potts et al., 2010). Some of these anthropogenic impacts are known to affect different pollinator groups in contrasting ways. ...
... Some of these anthropogenic impacts are known to affect different pollinator groups in contrasting ways. For instance, bees (i.e., Apidae) and hoverflies (i.e., Syrphidae), which are considered two of the most widespread and effective pollinator groups (Doyle et al., 2020;Potts et al., 2010;Willmer et al., 2017), can respond differently to landuse changes (Jauker et al., 2009;Persson et al., 2020). Despite the key importance of bees and hoverflies and their likely different responses to some anthropogenic impacts, we still know little about their relative contribution to the structure and dynamics of plant-pollinator systems when the whole community of plants and flower visitors is considered. ...
... Bumble bee species are experiencing a decline in almost all geographic regions where they are found (Cameron and Sadd 2020). This pattern of decline is attributed to a variety of factors, including habitat loss and fragmentation (Winfree et al. 2009, Hadley andBetts 2012), increased environmental contaminants (Sivakoff et al. 2020), introduced species (Herron-Sweet et al. 2016), pathogen spread (Arbetman et al. 2017), climate change (Soroye et al. 2020), and pesticides (Potts et al. 2010). While the effects of some pesticides on bumble bees, and bees in general, have received considerable attention (e.g., neonicotinoids, Blacquière et al. 2012, Stanley and Raine 2016, Zioga et al. 2020, Camp and Lehmann 2021, other agrochemicals are less well studied. ...
... Insect pollinators, including bumble bees, are experiencing population loss at the global scale (Goulson 2010, Potts et al. 2010, S. A. Cameron et al. 2011. Fungicides, in particular, are an understudied threat in the context of insect pollinator health (Cullen et al. 2019, Zubrod et al. 2019. ...
Bumble bees are declining across the globe. The causes of this decline have been attributed to a variety of stressors, including pesticides. Fungicides are a type of pesticide that has been understudied in the context of bumble bee health. As a result, fungicides are often applied to flowering plants without consideration of pollinator exposure. Recent work demonstrates that fungicides have sublethal effects in bumble bees, but little is known about how much fungicide it takes to cause these sublethal effects. To address this gap in the literature, we fed microcolonies of the common eastern bumble bee (Bombus impatiens CressonHymenoptera: ApidaeHymenoptera: ApidaeHymenoptera: ApidaeHymenoptera: Apidae) pollen contaminated with a range of fungicide concentrations. We chose these concentrations based on the range of fungicide concentrations in pollen and nectar that were reported in the literature. Results revealed that later-stage pupae and newly emerged males are potentially sensitive to fungicide exposure, showing smaller size and reduced fat reserves at intermediate levels of contamination. Compared to the control, intermediated levels of fungicide-contaminated pollen led to increased pupal mortality and delayed male emergence. Contrary to expectations, higher fungicide levels did not exhibit a linear relationship with negative impacts, suggesting nuanced effects. Because body size and emergence timing are important aspects of bumble bee reproductive behavior, results have implications for mating success, potentially disrupting colony development.
... influence on overall bee behavior patterns (Potts et al., 2010). Previous research has shown that temperature and light are the main factors influencing nest foraging behavior in several bee species. ...
... Apart from the pollination of agricultural crops, flower-visiting insects also contribute to the pollination of wild plants and play an essential role in maintaining biodiversity (Gallai et al., 2009;Wilcock & Neiland, 2002). Their recent decline makes the conservation of flower-visiting insects an urgent international concern (Hall & Martins, 2020;Nakahama et al., 2022;Potts et al., 2010;Wilcock & Neiland, 2002). ...
Abandoned land management threatens the maintenance of the diversity of flower‐visiting insects and flowering plants. In recent years, cattle grazing on abandoned land has been practiced in Japan to utilize the abandoned land and reduce cattle feed costs. It is important to elucidate the restoration effects that cattle grazing has on the biodiversity of abandoned lands in warm, humid climate regions, such as Japan. However, there are limited case studies that examine the restoration effects on flower‐visiting insects and flowering plants in Japan. In this study, we examined the effects of Tajima cattle grazing on the species richness and abundance of butterflies and flowering plants in abandoned lands in Muraoka‐ku, Kami Town, Hyogo Prefecture, Japan. Our results revealed that the vegetation height was lower and species richness and abundance of butterflies and flowering plants was higher in the grazing lands. However, the abandoned lands had a higher vegetation height and significantly lower species richness and abundance of butterfly and flowering plant. Grazing pressure positively and significantly affected the species richness and abundance of butterfly and flowering plant. These results indicate that grazing increased the species richness and abundance of butterfly and flowering plant. There was no significant difference in the species composition between the grazing and abandoned lands, and no significant indicator species were detected in the abandoned lands. We conclude that Tajima cattle grazing systems on abandoned lands can restore the species richness and abundance of butterfly as well as flowering plants.
... Segundo os produtores, a produção média anual varia de 10 a 50 quilos por colmeia, porém o desmatamento, os agrotóxicos e a evolução das condições climáticas prejudicam sua produção. A destruição das florestas reduz a pastagem apícola, os inseticidas podem causar a morte nas abelhas por intoxicação direta, enquanto os herbicidas e fertilizantes podem afetar indiretamente os polinizadores, diminuindo a disponibilidade de recursos florais, finalmente a mudança climática pode potencialmente interromper a interação polinizadores-plantas polinizadas nas suas interdependências morfológicas e fisiológicas (POTTS et al., 2010). ...
Resumo: No estado catarinense, a atividade apícola tem evoluído, principalmente, como atividade de pequena produção e a certificação orgânica é parte das estratégias de produto diferenciado na inserção no mercado. Assim, o objetivo deste trabalho é caracterizar, de forma dinâmica, a cadeia produtiva de mel em Santa Catarina, com foco em pequenos produtores, para avaliar as potencialidades e os desafios na certificação orgânica. Este estudo usa o método de Diagnóstico Sucinto e Participativo das cadeias produtivas. As informações foram obtidas por meio de entrevistas informais com dirigentes e técnicos apícolas, questionários estruturados com produtores e entrevistas semiestruturadas com os entrepostos (intermediários) de todo o estado, como também de dados estatísticos do Brasil (IBGE) e outras publicações. Os resultados mostram que a certificação orgânica é incipiente ainda por parte dos produtores. Mas os entrepostos e as associações são os principais agentes em ajudar os apicultores na gestão da certificação orgânica. Além disso, a maioria da produção orgânica do mel é destinada para exportação, já que o consumo nacional é baixo. Palavras-chave: mel, cadeia produtiva, certificação orgânica Abstract: In Santa Catarina state, the beekeeping has evolved mostly as an activity of small production and organic certification is part of the strategies in differentiated product in the market integration. The objective of this paper is to characterize, in a dynamic way, the honey supply chain in Santa Catarina, with a focus on small producers, to assess the potential and challenges in organic certification. This study uses the method of Succinct and Participatory Diagnosis of supply chain. Information was obtained through informal interviews with leaders and technicians, structured questionnaires with producers and semi-structured interviews with intermediate traders from around the state, as well as statistical data of Brazil (IBGE) and other publications. The results show that organic certification is still emerging from the producers. But intermediate traders and associations are key players in helping to beekeepers in the management of organic certification. In addition, most organic honey production is destined for exports, since domestic consumption of honey is low.
... Bee species are both conservation targets and pollinators whose functions affect many plant species. A worldwide decline in wild bee populations has been repeatedly reported [2][3][4][5][6] , raising concerns about the deterioration of pollination services. The deterioration of pollination services causes a consequent decline in bee-pollinated wild plant populations, and the decline in wild plant populations in turn causes a shortage of floral resources and the further decline of wild bee populations. ...
The decline of wild bee populations causes the decline of bee-pollinated plant populations through the deterioration of pollination services. Since high bee species richness generally involves high functional group diversity, protecting areas of high bee species richness will help to maintain pollination services for plants. However, those areas do not always include the habitats of bee species with specialized functions that expand the range of plants being pollinated. To map important areas for protecting native bee species and their functions, we estimated the distributions and functional range of 13 bumble bee species and 1 honey bee species in Japan. The distributions were estimated from an ensemble of six species distribution models using bee occurrence data and environmental data. The functional range of bee species was estimated by combining the estimated distributions and proboscis length, which frequently corresponds to the floral shape of the plant species they pollinate. The estimated species richness was high in western Hokkaido and the estimated functional range was wide in central Honshu. Our method is useful to see whether areas important for high species richness of pollinators differ from those for rare species or their functions.
... For example, when a top predator is removed, resulting in prey overpopulation and resource depletion, surviving species may be forced to disperse to new areas in search of food, altering their traditional movement patterns [97][98][99][100]. Similarly, the loss of key pollinators could disrupt food webs, prompting species that relied on those pollinated plants for food to expand their search for resources, thus modifying their dispersal routes [101,102]. These shifts in dispersal are critical for understanding ecosystem resilience and the cascading effects of biodiversity loss. ...
Dispersal is a key process in ecology and evolution. While the effects of dispersal on diversity are broadly acknowledged, our understanding of the influence of diversity on dispersal remains limited. This arises from the dynamic, context-dependent, nonlinear and ubiquitous nature of dispersal. Diversity outcomes, such as competition, mutualism, parasitism and trophic interactions can feed back on dispersal, thereby influencing biodiversity patterns at several spatio-temporal scales. Here, we shed light on the dispersal–diversity causal links by discussing how dispersal–diversity ecological and evolutionary feedbacks can impact macroecological patterns. We highlight the importance of dispersal–diversity feedbacks for advancing our understanding of macro-eco-evolutionary patterns and their challenges, such as establishing a unified framework for dispersal terminology and methodologies across various disciplines and scales.
This article is part of the theme issue ‘Diversity-dependence of dispersal: interspecific interactions determine spatial dynamics’.
... Інфекційні хвороби бджіл є серйозною проблемою, оскільки призводять до загибелі бджіл, ослаблення сімей, негативного впливу на довкілля, зниження врожайності сільськогосподарських культур та погіршення якості та безпеки продуктів бджільництва. Розробка системи епізоотологічного моніторингу, спрямована на виявлення джерел і резервуарів збудників інфекційних хвороб, має велике значення для контролю і профілактики цих захворювань, а також для утримання (Potts et al., 2010) сильних бджолиних сімей і подальшого розвитку галузі. ...
В статті наведені результати вивчення впливу зміни погодних умов та клімату на життєздатність медоносних бджіл у Чернігівській області. Зміна клімату є актуальним питанням, оскільки може мати серйозні наслідки для продуктивності пасік та екологічної рівноваги. Мета дослідження полягає у вивченні змін у популяціях медоносних бджіл, їх фізіологічному стані та продуктивності внаслідок зміни клімату. Дослідження показало, що зміни кліматичних умов впливають на фізіологічний стан і продуктивність медоносних бджіл. Досліджували 18 пасік, в активний та неактивний сезон 2023 року, було діагностовано розвиток мікозних хвороб, вапняний розплід (аскофероз) реєстрували на 10 пасіках (55,55 %), кам’яний розплід (аспергильоз) на 2 пасіках (11,11 %), а грибкові хвороби змішаного перебігу зареєстровано на 3 пасіках (16,66 %), на 1 пасіці бактеріози (5,55 %) і на 2 пасіках паразитози (11,11 %). Регіональна захворюваність вапняним розплодом відмічена в Чернігівській області у південно-східній частині (66,66 % позитивних зразків). Сезон захворюваності вапняного розплоду показує, що понад 38,8 % випадків приходиться на кінець бджільницького сезону, а в неактивні місяці сезону (січень – лютий) захворюваність мінімальна (11,11 % випадків). Це пояснюється залежністю від еволюції розвитку розплоду у вуликах і, ймовірно, завдяки захисному ефекту прополісу, яким вулики оббиті на кінці активного сезону, що має антисептичну дію в період простою (листопад, грудень, січень і лютий). Відбувається незначне збільшення кількості випадків у весняні місяці (березень, квітень, травень), коли бджолиний розплід розвивається (22,22 %) і прогресивно зростає влітку (червень, липень, серпень). Наявність вапняного розплоду в 55,55 % випадків, разом з основними бактеріальними захворюваннями, показує що загальний елемент хворобливих бактерій і грибкові утворення перебувають у дефіциті імунітету система. Отже, дана робота є важливим внеском у розвиток наукових знань про екологічні взаємодії та сприяє подальшим дослідженням у цій галузі. Висновки та рекомендації, представлені у роботі, можуть бути використані для практичної реалізації стратегій захисту та підтримки популяцій медоносних бджіл у змінених кліматичних умовах.
... Unfortunately, there is a concerning bee population decline worldwide in which parasites and pathogens, more specifically viruses, are aggravating factors alongside climate change, habitat loss, and pesticides [2][3][4]. This problem has been recently highlighted in Brazil through a long-term survey of bee losses [5], a comprehensive literature review [6] and two online questionnaires [7]. ...
Bees are fundamental for maintaining pollination-dependent plant populations, both economically and ecologically. In Brazil, they constitute 66.3% of pollinators, contributing to an annual market value estimated at R$ 43 billion for pollination services. Unfortunately, worldwide bee populations are declining due to parasites and pathogens, more specifically viruses, alongside climate change, habitat loss, and pesticides. In this scenario, extensive research concerning bee diversity, virus diversity and surveillance, is necessary to aid the conservation of native managed pollinators and potential wild alternatives besides mitigating the emergence and spread of viral pathogens. A decrease in pollination can be a point of economic vulnerability in a country like Brazil because of its main dependence on food exports. Here we conducted a study aiming to obtain an overview of circulating viruses in bees within Brazilian territory highlighting the need for further studies to have a more realistic view of bee-infecting viruses in Brazil.
... Urban environments can be challenging for wild bee communities for several reasons. First, these areas are highly impervious, resulting in the loss and fragmentation of habitats that are suitable for wild bees, as well as the reduction of their floral and nesting resources (Geslin et al., 2016;Hamblin et al., 2018;Potts et al., 2010). Moreover, a large part of the floral resources found in cities are provided by ornamental flowers, in private gardens and public parks, that can be less attractive to pollinators than native plants (Erickson et al., 2020;Garbuzov et al., 2017;Garbuzov & Ratnieks, 2014). ...
In the context of worldwide biodiversity and wild bee decline, it is increasingly important to better understand the effect of land-use changes on wild bee communities at a global scale. To do so, we studied the effect of city area and urban green spaces layout on wild bee species richness and community composition, as well as on wild bee species with an unfavorable UICN conservation status. This study was based on a large European dataset encompassing 20 cities from France, Belgium and Switzerland. We found a mean wild bee species richness in cities of 96 ± 48 (SD), showing that this species richness was highly variable among cities. The main factor positively influencing wild bee species richness in cities was the area of the city. Conversely, species richness was not significantly related to the total area of urban green spaces in a given city, measured as the spatial extent of urban parks, wastelands and other semi-natural habitats, excluding urban private gardens. Species with conservation status were quite scarce in urban environments, especially when compared to the European Red List of Bees, and we could not link their presence to either city or urban green space area. Dissimilarities in wild bee species community compositions were not associated with any of the studied characteristics of cities. We found that the dissimilarity of wild bee community composition among cities was mainly driven by the rarest species, as the most common ones were found in a majority of the cities sampled. Overall, these results emphasize that larger cities host more wild bee species, but are no refuge for the ones with concerning conservation status. Thus, stakeholders are encouraged to design their cities in favor of biodiversity to better support wild bee communities, and perhaps mitigate the established effect of the urban ecological filter.
... Worldwide, 75% of the crops that humans consume (Klein et al., 2007) and 80% of wild plants (Potts et al., 2010) rely on pollinators for successful reproduction (Free, 1993;Jordan et al., 2021). Bees provide the majority of these pollination services (Free, 1993;Willmer et al., 2017). ...
Bee declines pose a serious risk to agricultural sustainability, wild plant diversity, and the commercial bee industry, generating local and global concerns about bee health. Parasites, including micro‐parasites and macro‐parasites, negatively impact bee population dynamics. Management of parasites requires an understanding of the cyclic trends in prevalence and the factors impacting these patterns. In this study, we advance understanding of parasite epidemiology and transmission among members of the bee community toward the goal of improving predictability of parasite prevalence seasonally. Honey bees and bumble bees were collected throughout an active season and across multiple overwintering periods. These bees were molecularly tested for two common bee viruses—deformed wing virus (DWV) and black queen cell virus (BQCV)—and morphologically screened for Vairimorpha spp., nematodes, and parasitic flies to determine whether these parasites exhibit unique seasonal trends, if overwintering behavior impacts parasite survival, and how these patterns differ between honey bees and bumble bees. The results suggest consistent seasonal trends between honey bees and bumble bees; however, these trends are parasite‐specific. Honey bees consistently exhibited a higher magnitude of viral prevalence compared with bumble bees. Both honey bees and bumble bees reduced viral prevalence over the winter; however, only in bumble bees did this drop to negligible prevalence each spring. These data suggest that honey bees may have a larger impact on parasite transmission, as they pose to reinfect bees which otherwise would have very low prevalence each spring and sustain high levels of infection in communities year‐round.
... We were not able to determine the causes of lack of native pollinators in some study sites, but we hypothesise that anthropogenic habitat alteration (disturbance linked to urban development) might have led to their decline 96,98 . Given that Trichocolletes native bees are ground-nesting bees 97 , habitat change might interfere with nesting and foraging sites 4,99,100 , eventually leading to their local loss. ...
Biological invasions threaten global biodiversity, altering landscapes, ecosystems, and mutualistic relationships like pollination. Orchids are one of the most threatened plant families, yet the impact of invasive bees on their reproduction remains poorly understood. We conduct a global literature survey on the incidence of invasive honeybees (Apis mellifera) on orchid pollination, followed by a study case on Australian orchids. Our literature survey shows that Apis mellifera is the primary alien bee visiting orchids worldwide. However, in most cases, introduced honeybees do not deposit orchid pollen. We also test the extent to which introduced honeybees affect orchid pollination using Diuris brumalis and D. magnifica. Diuris brumalis shows higher fruit set and pollination in habitats with both native and invasive bees compared to habitats with only introduced bees. Male and female reproductive success in D. magnifica increases with native bee abundance, while conversely pollinator efficiency decreases with honeybee abundance and rises with habitat size. Our results suggest that introduced honeybees are likely involved in pollen removal but do not effectively deposit orchid pollen, acting as pollen wasters. However, Apis mellifera may still contribute to pollination of Diuris where native bees no longer exist. Given the global occurrence of introduced honeybees, we warn that certain orchids may suffer from pollen depletion by these invaders, especially in altered habitats with compromised pollination communities.
... This role significantly contributes to the world food security and sustainable development of global ecosystems. 1 Unfortunately, the health and survival of honey bees are facing numerous threats, including habitat loss and fragmentation, increased pesticide application and environmental pollution, the spread of pathogens and parasites, nutrition deficiency, long-distance transport of hives, and the effects of climate change. [2][3][4] The obligate ectoparasite, Varroa destructor Anderson and Trueman has long been considered as the most damaging pest of the Western honey bee, Apis mellifera L., resulting in a substantial colony losses. [5][6][7] The health of honey bees is jeopardized not only by the feeding of Varroa, but also by its transmission of various dreadful viruses. ...
BACKGROUND
The parasitic mite, Varroa destructor has posed a threat to the health and survival of European honey bees, Apis mellifera worldwide. There is a prevailing belief that small comb cells could provide a management tool against Varroa mites. However, the hypothesis that smaller cells can impede Varroa reproduction has not been fully tested. Here, we tested this hypothesis under laboratory conditions by using two distinct Varroa in vitro rearing systems: one involved gelatin capsules of different sizes, specifically size 00 (0.95 mL) versus size 1 (0.48 mL), and the second consisted of brood comb cells drawn on 3D printed foundations with varying cell sizes, ranging from 5.0 mm to 7.0 mm at 0.5 mm intervals.
RESULTS
The results showed that mother mites in size 00 cells had significantly lower fecundity and fertility compared to those in size 1 cells. Interestingly, the reproductive suppression in larger cells could be reversed by adding an extra worker larva. Similarly, gonopore size of mother mites was smaller in size 00 cells, but restored with another host larva. Furthermore, both the fecundity and fertility of mother mites decreased linearly with the size of brood comb cells.
CONCLUSIONS
Our results suggest that the reproduction of V. destructor is hindered by larger cells, possibly because larger brood cells disperse or weaken host volatile chemical cues that are crucial for Varroa reproduction. The insights derived from this study are expected to hold significant implications for the implementation of Varroa management programs. © 2024 Society of Chemical Industry.
... [34]. However, in recent years, reports on the decline in honeybee pollination have been common, posing a serious threat to biodiversity and global food security [35][36][37]. McMahon D.P. et al. reported that deformed wing virus (DWV), one of the Iflavirus virus, can infect honeybees through Varroa and Tropilaelaps, resulting in a dramatic decrease in the number of honeybees [38]. When DWV infects honeybees, it can spread vertically within the bee population and increase the prevalence of the virus among honeybees [38]. ...
Pyrops candelaria is one of the common pests of fruit trees, but the research on the pathogenic microorganisms it may carry is very limited. Therefore, it is essential to reveal the pathogenic microbes it carries and their potential hazards. This study found a new virus from the transcriptome of P. candelaria, which was first reported in P. candelaria and named as PyCaV (Pyrops candelaria associated virus). RACE and bioinformatics assay revealed that the full-length of PyCaV is 10855 bp with the polyA tail, containing a single open reading frame (ORF) encoding a polyprotein consisting of 3171 amino acid (aa). The virus has a typical Iflavirus structure, including two rhv domains, a RNA helicase domain (HEL), a 3C cysteine protease domain (Pro), and a RNA-dependent RNA polymerase domain (RdRp). Further phylogenetic analysis revealed that this virus belongs to family Iflaviridae and sequence alignements analysis suggedted PyCaV is new member in unassigned genus of family Iflaviridae. Further in-depth analysis of virus-infection-part showed that PyCaV is distributing in the whole longan lanternfly, including its head, chest, and abdomen, but more PyCaV was identified in the chest. The distribution of PyCaV in different parts of P. candelaria was further explored, which showed that more PyCaV were detected in its piercing-sucking mouthparts and chest viscera. Statistical analysis showed that the PyCaV infection was affected by time and locations.
... Anthropogenic land-use changes leading to habitat loss and deterioration are key drivers of global biodiversity declines, which threaten to destabilise ecosystem functions related to animal pollination Winfree, 2013). Given that the vast majority of all flowering plants and many important crops benefit from animal pollination, these declines could potentially negatively impact the diversity of wild plant communities as well as crop production worldwide (Klein et al. 2007;Potts et al. 2010;Ollerton et al. 2011). The world's largest terrestrial biome, the boreal forest, is home to an estimated 100 000 species across taxa, of which 20% have been identified (Ruckstuhl et al. 2008;Burton et al. 2010). ...
Intensification of forest management to increase production of biomass has resulted in considerable habitat degradation with negative impacts on insect biodiversity, including beneficial insect groups such as pollinators. Yet, little is known about how reliant forest understory plants, such as bilberry (Vaccinium myrtillus), are on insect pollinators for reproduction. Here, we quantified the structure of the bilberry flower visitor community, compared the pollination effectiveness of the most common pollinators, and experimentally quantified bilberry pollination dependency. The bilberry pollinator community was comprised of several bee and hoverfly taxa. Bumblebees were the most important pollinators due to their high abundance and pollination effectiveness. Other bees, in particular, Andrena spp., and to a smaller extent, hoverflies, were also effective pollinators. Furthermore, bilberry was strongly pollen-limited, with only 40% of open-pollinated flowers setting fruit. Bilberry supports a diverse flower visitor community within hemi-boreal forests, for which it is highly dependent for reproduction. Given the ecological and cultural value of bilberry, the importance of insect pollinators for understory plants should be considered within forest management strategies.
... A wide variety of species of insects that pollinate plants have coevolved with plants, resulting in biodiversity and productive landscapes (Wojcik 2021). However, various factors, including the availability of floral resources, climatic conditions, land use changes, and the presence of invasive species, can influence these interactions (Dicks et al. 2016, Potts et al. 2010. ...
From September 2021 to August 2022 a study was carried out to
assess the species diversity and abundances of pollinators and plant-pollinator interactions in Puthia Upazila of Rajshahi District, Bangladesh. A total of 3284 individuals were recorded, in which 109 species of 87 genera were identified as belonging to 49 families and 12 orders under three classes (Insecta, Aves and Mammalia). The relative abundance of insects and non-insect pollinators was 91.57% and 8.43%, respectively. A maximum of 32 species (relative abundance, RA= 32.70 %) was observed in the order Lepidoptera and minimum in the order Chiroptera (1 species; RA= 0.09 %). The most abundant family was Apidae (n=
267, RA= 8.12%) and the most dominant species was Eurema hecabe (n= 95, RA= 2.89%) (Family: Pieridae, Order: Lepidoptera). Based on number of individuals (n), the status of pollinators: 25 species were very common, 29 species were common, 18 species were fairly common, 21 species were rare and 16 species were very rare. A total of 51 flowering plants were documented that were visited by the pollinators, of which 32 were crop plants and 19 were non-crop flowering plants. Among them, the flowers of Orangeberry (Glycosmis pentaphylla) received the greatest number of pollinator species, i.e., 55. Overall, 79 species of recorded pollinators visited non-crop flowering plants, 65 species visited crop plants, and 35 species were common in both. According to the obtained individuals, the Shannon (H') and Simpson (1-D) diversity indices were 4.41 and 0.99, respectively. The Berger-Parker dominance (d) and Pielou's evenness index (J') were 0.03 and 0.94, respectively, while the Margalef (DMg) and Menhinick (DMn) species richness indices were 13.34 and 1.90, respectively. The present study is the first report to offer baseline abundance and diversity of main pollinator groups in agroecosystems and provide data for a checklist of the variety of pollinators in the Puthia Upazila, Rajshahi, Bangladesh.
... In addition to the evolution of self-compatibility, we may also expect an increase in the selfing rate of self-compatible plants in fragmented habitats. Clearly, more studies are needed to understand the consequences of changes in plant mating systems in disturbed and fragmented landscapes. 5. Land-use change and other synergistic drivers, such as agriculture intensification, pesticide use and climate change, have a significant impact on pollinator decline (Potts et al., 2010;Goulson et al., 2015;Guedes et al., 2016). Although the direct relationship between pollination and plant reproductive success has been demonstrated, few studies have examined the effect of changes in pollinator assemblages on plant reproduction and the structure of plant-pollinator networks in human-disturbed fragmented habitats (Astegiano et al., 2015;Cortés-Flores et al., 2023). ...
Background and Aims The majority of the Earth's land area is currently occupied by humans. Measuring how terrestrial plants reproduce in these pervasive environments is essential for understanding their long-term viability and their ability to adapt to changing environments. • Methods We conducted hierarchical and phylogenetically independent meta-analyses to assess the overall effects of anthropogenic land-use changes on pollination, and male and female fitness in terrestrial plants. • Key Results We found negative global effects of land-use change (i.e. mainly habitat loss and fragmentation) on pollination and on female and male fitness of terrestrial flowering plants. Negative effects were stronger in plants with self-incompatibility systems and in plants pollinated by invertebrates, regardless of life form and sexual expression. Pollination and female fitness of pollination-generalist and pollination-specialist plants were similarly negatively affected by land-use change, whereas male fitness of specialist plants showed no effects. • Conclusions Our findings indicate that angiosperm populations remaining in fragmented habitats negatively affect pollination, and female and male fitness, which will probably decrease the recruitment, survival and long-term viability of plant populations remaining in fragmented landscapes. We underline the main current gaps of knowledge for future research agendas and call not only for a decrease in the current rates of land-use changes across the world but also to embark on active restoration efforts to increase the area and connectivity of remaining natural habitats.
... Among the multiple pressures that land use change imposes on pollinators [1,7,8], floral resource limitation due to a decline in preferred flowering species or increases in non-suitable floral resources, such as non-native plants [9,10], strongly contribute to pollinator declines [8,11,12], particularly of larger bee species [13]. Moreover, parallel declines in insect-pollinated plant species following declines of their pollinators [14] highlight strong interdependencies that mediate their joint responses to land use change [15]. ...
Land use change alters floral resource availability, thereby contributing to declines in important pollinators. However, the severity of land use impact varies by species, influenced by factors such as dispersal ability and resource specialization, both of which can correlate with body size. Here. we test whether floral resource availability in the surrounding landscape (the ‘matrix’) influences bee species’ abundance in isolated remnant woodlands, and whether this effect varies with body size. We sampled quantitative flower-visitation networks within woodland remnants and quantified floral energy resources (nectar and pollen calories) available to each bee species both within the woodland and the matrix. Bee abundance in woodland increased with floral energy resources in the surrounding matrix, with strongest effects on larger-bodied species. Our findings suggest important but size-dependent effects of declining matrix floral resources on the persistence of bees in remnant woodlands, highlighting the need to incorporate landscape-level floral resources in conservation planning for pollinators in threatened natural habitats.
... In Brazilian the global economy, estimated at around US$ 577 billion (Potts et al., 2017). However, these services face threats due to environmental degradation and biodiversity loss resulting from agricultural expansion to meet the growing world population (Potts et al., 2010;Rosa et al., 2019). The economic benefits of ecosystem pollination services exceed half a billion dollars globally (Lautenbach et al., 2012;Potts et al., 2017;Aizen et al., 2019). ...
The increasing global importance of pink peppertree (Schinus terebinthifolia, Anacardiaceae) as a high-value commercial crop and its potential for expansion in production demand appropriate management due to uncertainties regarding its sexual system. This study focused on evaluating the morphology of sterile and fertile floral whorls, as well as analyzing the sexual system of pink pepper in two populations in northeastern Brazil. The results revealed no significant differences in the morphological characteristics of the flowers between the studied areas, suggesting that the species possesses notable adaptability to environmental conditions. However, a significant difference in the proportion of staminate individuals was observed in both areas, representing over 88% and 72%, respectively. A correlation was observed between the size of the stamens and the presence of apparently atrophied pistils (r=0.275; df=178; p<0.001), along with the occurrence of fruits in these hermaphroditic plants. In this context, the species should be considered gynodioecious due to the presence of plants with hermaphroditic flowers and plants with pistillate flowers. However, further research is essential to elucidate the role of pollinators, especially bees and wasps, and to better understand the fruiting process in hermaphroditic flowers. These insights have the potential to significantly enhance management aiming for efficient fruit production, promoting its economic and ecological relevance.
... Bee abundance and richness are suspected to be in decline in many areas and this may be caused by a combination of factors. Intensive agriculture (Potts et al. 2010), habitat loss, fragmentation and degradation, all affect the availability of key foraging and nesting resources (Tscheulin et al. 2011). It is known that olive groves which are regularly plowed have higher bee species richness than in other habitat types, such as pine forests (Potts et al. 2006). ...
The agricultural sector has been intensifying production systems to increase yields. Olive cultivation is the most widespread permanent crop in Europe and the Mediterranean region and in many cases, it is under intensive farming practices with heavy use of agrochemicals, greatly affecting olive grove biodiversity. In this study we investigate the impact of different understorey management practices (undisturbed, cleared with mechanical means) on plant cover, ground beetle and bee richness and abundance, and on the abundance of ground arthropods and flying insects in olive groves on Lesvos Island, North Aegean, Greece. We found that undisturbed understorey had a positive impact on plant richness and abundance, ground beetle and bee richness and abundance, as well as ground arthropod and flying insect abundance. The results suggest that maintaining the plant cover undisturbed significantly improves the biodiversity of the olive groves and by extension the ecosystem services, such as pollination, pest control and soil health.
... Insectenpopulaties vertonen de laatste decennia een sterke achteruitgang (Hallmann et al. 2017, Wagner et al. 2021, waarbij vooral de achteruitgang van bestuivers en hun cruciale rol in verschillende ecosystemen mensen zorgen baart (Potts et al. 2010, Dicks et al. 2021. De voornaamste oorzaken voor deze achteruitgang liggen in een combinatie van biotoopverlies (wat resulteert in een verminderd nectar-en pollenaanbod en een verlies aan nestplaatsen) en -versnippering (Kruess & Tscharntke 1994), pesticiden (Goulson et al. 2015), klimaatverandering (Vasiliev & Greenwood 2021) en invasieve soorten (Rodríguez et al. 2023). ...
The strong and rapid decline of pollinators and other insects has recently drawn attention from both scientists and the media. The main threats to insects are habitat loss and fragmentation, pesticides, climate change and invasive species (such as the Yellow-legged Hornet Vespa velutina). To halt this decline it is important to conserve and manage areas that are important for insects in general and for pollinators in particular. Using a recently published report on important European
habitat types for pollinators (Kudrnovsky et al. 2020), we delineate potentially important areas for pollinators in Flanders. In total we identified 226,156 hectares of such areas, of which 79,074 hectares (35%) are located in Natura2000 areas. Grasslands (92,857 ha) occupy the largest share of important pollinator areas in Flanders, followed by non-Habitats Directive biotopes (51,892 ha) and forests (44,863 ha). The best protected pollinator habitats by Natura2000 are coastal habitats and halophytic vegetations and coastal dunes (both 94%), followed by heathland and shrub (67%). Important grassland habitats (24%) and non-European habitat types (17%) however are poorly represented in Natura2000 areas. The maps produced here can be useful in protecting important areas for pollinators, as well as in setting priorities for eradicating the Yellow-legged Hornet or to mitigate the impact of cultivated Honeybees on wild pollinators. Finally we call for the establishment of a monitoring network for pollinators in Flanders so that trends in their abundance can be closely monitored.
... Considering the ecosystem benefits offered by pollinator communities and the detrimental impact of human activities on them (Nath et al., 2023;Potts et al., 2010), it is imperative to broaden our understanding of overlooked flower visitors, even though their contribution to pollination may not be as important as that of other pollinator groups. In the specific case of velvet ants, we have taken the first step into this knowledge gap, but more studies are necessary to confirm their role as pollinators as well as their relative importance and contribution to pollination. ...
Plant-animal interactions constitute a recurrent and central focus in ecological research , with pollination representing one of its most extensively studied aspects. While certain insect orders have traditionally received considerable attention due to their abundance as flower visitors and their efficiency in pollination, it is undeniable that the significance of other less popular and neglected flower visitors cannot be overlooked. In this regard, velvet ants (Hymenoptera: Mutillidae and Myrmosidae) constitute an excellent study model, as the knowledge of their ecology (e.g., their feeding preferences) is still very limited despite being reported as common flower visitors. In this study, we conducted a comprehensive global review of velvet ant floral visitation patterns using citizen science data, literature records and unpublished data. We used network metrics to explore their flower-visit preferences on a global scale, as well as depending on the bioregion where the interaction was recorded and the sex of the velvet ants. In addition, we explored their potential role as pollen vectors examining the number of photographic records where velvet ants had pollen attached to their bodies. Our analyses revealed that velvet ants are generalist flower visitors of a wide range of plant families, with Apiaceae, Asteraceae, Euphorbiaceae, Rhamnaceae and Fabaceae as the most visited. Despite differences in flowering plant and velvet ant composition across bioregions causing differences in plant-velvet ant interactions, velvet ants visited flowering plants in a generalistic way across the globe. Males and females seemed to visit different plant communities, with males being more generalist than females. Furthermore, 42.7% (likely an underestimation) of the photographic records of velvet ants visiting flowers showed pollen attached to their bodies in the same way as in other pollinating insects, suggesting the same potential role as pollinators. There remains ample scope for ongoing investigation to comprehensively assess the importance of numerous arthropods, including velvet ants, not only as flower visitors but also as potential pollinators.
... До зовнішніх факторів належать природно-кліматичні умови навколишнього середовища, наявність медоносної бази місцевості та її географічне розміщення тощо. Можливість впливати на них з боку людини є обмеженою (Potts et al., 2010;Settele et al., 2016;Nedashkivskyi & Mishchenko, 2021). Друга група факторів створюється всередині гнізда і має дуже важливе значення для життєздатності та продуктивності бджолосім'ї (DeGrandi-Hoffman et al., 2017;Kovalʹsʹkyy et al., 2017). ...
The survival of bee families during hypobiosis is considered the most critical period of their life. It correlates with the number of workers in the nest, that is, the strength of the family. The article presents one of the possible implementations of the potential of bee families to increase their strength before the period of hypobiosis. The proposed technology involves using auxiliary queens in temporary families formed before wintering from their maternal families. The work aimed to study the effectiveness of using this retention technology. For research, two groups of families created by analogs were formed. There were 5 bee families in each group. In the research group, on July 30, one litter was made from each maternal research family. Thus, before the beginning of the period of hypobiosis in experimental families, the number of offspring was obtained from two queens. A characteristic feature of the control group was the presence in the nest of brood obtained from only one queen. The conducted studies indicate that using temporary families during the preparation of bees for the state of hypnosis ensured a significant increase in the strength of bee colonies. As a result of the proposed technology, the strength of the families of the experimental group exceeded the control group by 22.2 % (Р < 0.001). The proposed technology made it possible to completely replace the queens of maternal families with young queens from temporary families.
... In line with our first hypothesis, temporal variations in oribatid mite density and species number differed between regions, largely driven by fluctuations in precipitation rather than forest management. Previous studies in this context have focused on grasslands and shrub lands, where the causality between the intensification of management practices over the last decade, and negative impacts on biodiversity, is more straightforward (Potts et al. 2010). Forest ecosystems have a high structural complexity with a myriad of microhabitats and may therefore buffer soil animals against land-use effects or climatic variability to some extent (Birkhofer et al. 2017, Seibold et al. 2019, Frenne et al. 2021). ...
Biodiversity and biomass of aboveground arthropods in central European forests continuously declined during the last decade. However, whether belowground microarthropod communities follow similar patterns has not been investigated. In this study, we compared the abundance, diversity, community composition, stability and asynchrony of oribatid mites (Acari: Oribatida) sampled in four forest types of increasing management intensity (unmanaged beech, old managed beech, young managed beech, and coniferous) at three‐year intervals from 2008 to 2020. Forest sites were replicated in three regions in southern, central and northern Germany, i.e. the Swabian Alb, Hainich‐Dün and the Schorfheide Chorin, which differ in soil characteristics and climate. We found 25 152 individuals and 121 species of oribatid mites and detected no linear decline in abundance and diversity over the last decade, suggesting that microarthropods in forest soils are buffered against land‐use effects. However, we observed that years with low winter precipitation in regions with soils that are prone to drought, resulted in significant decreases in oribatid mite densities. Community compositions remained similar across sampling years, but differed between regions and forest types, predominantly due to differences in the proportion of asexual individuals. The stability of oribatid mite communities did not decrease in managed forests and was highest in deep soils with high water‐holding capacity, which may reduce temporal variation, suggesting that soil properties are more important for the stability of oribatid mite communities than forest management. However, stability patterns were not explained by asynchrony in species fluctuations, as all communities either showed a high degree of synchrony or were not different from random. Our study highlights that the temporal dynamics of belowground communities may differ from those aboveground, and that regional differences in precipitation and soil properties are more important than forest types.
... Honey bees (Apis mellifera) are important pollinators of many crops (Klein et al. 2007;Gallai et al. 2009;Potts et al. 2010;Breeze et al. 2011;Hung et al. 2018). While the total number of honey bee colonies has increased worldwide (Phiri et al. 2022), pressures from pesticides, pests, diseases, heavy metal pollution, extreme weather, and lack of forage (Smith et al. 2013;Goulson et al. 2015;Steinhauer et al. 2018;Insolia et al. 2023;Yang et al. 2023) have led to widespread annual colony losses (Gray et al. 2022). ...
Honey bee ( Apis mellifera ) breeding has intensified as populations experience increasing stress and pollination demand increases. Breeding programmes risk genetic diversity losses as mating is focused on a small group of individuals. Loss of diversity at the complementary sex determiner ( csd ) locus results in decreased viability and reduced honey production. Bees that are homozygous at csd become inviable males rather than workers. We examined csd diversity in four Australian breeding populations: a queen bee breeder from New South Wales, another from Queensland, a Western Australian breeding programme involving 11 bee breeders, and a research population at the NSW Department of Primary Industries. We found 82 unique csd alleles across the four populations, 16 of which have not been previously reported. This study provides a snapshot of csd diversity in Australia which will be useful for the national honey bee genetic improvement programme (Plan Bee).
... Abundance and diversity of insects is in decline (1)(2)(3)(4) especially in regions with industrialized agriculture (5). This loss of biomass and ecological functions can imply serious consequences for food chains in ecosystems (6) and pollination services of our crops (7). Rapid changes for conservation require rapid diagnostic tools to assess insect abundance and diversity. ...
Identification of insects in flight is a particular challenge for ecologists in several settings with no other method able to count and classify insects at the pace of entomological lidar. Thus, it can play a unique role as a non-intrusive diagnostic tool to assess insect biodiversity, inform planning, and evaluate mitigation efforts aimed at tackling declines in insect abundance and diversity. While species richness of co-existing insects could reach tens of thousands, to date, photonic sensors and lidars can differentiate roughly one hundred signal types. This taxonomic specificity or number of discernible signal types is currently limited by instrumentation and algorithm sophistication. In this study we report 32,533 observations of wild flying insects along a 500-meter transect. We report the benefits of lidar polarization bands for differentiating species and compare the performance of two unsupervised clustering algorithms, namely Hierarchical Cluster Analysis and Gaussian Mixture Model. We demonstrate that polarimetric properties could be partially predicted even with unpolarized light, thus polarimetric lidar bands provide only a minor improvement in specificity. Finally, we use physical properties of the clustered observation, such as wing beat frequency, daily activity patterns, and spatial distribution, to establish a lower bound for the number of species represented by the differentiated signal types.
... Bees have an essential ecological role and provide the fundamental ecosystem service of pollination. However, there is increasing evidence for their decline (Potts et al. 2010) along with a possible reduction in their distribution (Gómez-Ruiz and Lacher 2019; González et al. 2021) because of global change. However, recent colonization of new areas by natural movements, leading to geographical expansion, was reported in several bee species (Dew et al. 2019;Rahimi et al. 2021;Sheffield and Palmier 2023). ...
Climate change and/or land use change were repeatedly reported as important for both range expansion of alien bee species and range shrinking for native bee species. However, environmental changes may also positively affect native species that may expand across contiguous areas to their native ones. Here, we focused on Halictus scabiosae (Rossi, 1790) (Hymenoptera: Halictidae), a ground-nesting, primitively eusocial wild bee that has its primary distribution in Western-Southern Europe but that was recently recorded in Eastern-Central Europe. In particular, we studied the range expansion patterns of H. scabiosae, and we hypothesized that previously unsuitable areas may be currently colonized because of environmental changes. In the last 5 years, H. scabiosae moved its densest record areas to NorthEastern Europe, but its ecological niche remained almost unchanged from 1970 to date, suggesting that this bee species is following its preferred conditions (high temperature, high temperature seasonality, and low precipitation seasonality). Potential distribution models revealed high suitability in still unoccupied NorthEastern areas, with urbanization increasingly important as potential stepping stones towards the expansion. The relevant role of urbanization is confirmed by the increase in the number of urban records through time and by the fact that cities with greater population density and greater fragmentation are more likely associated with this species' occurrence. Halictus scabiosae is thus expanding its range because climate change is producing-and urban environment is offering-suitable conditions in areas previously inadequate for its establishment.
Keywords: Halictus scabiosae / Halictidae / climate / urbanization / species distribution models
... Bees, butterflies, birds, and other pollinators are very sensitive to environmental changes, making them particularly vulnerable to the impacts of climate change. Since pollinators are essential to crop pollination and food production, the effects of climate change on them will have a huge influence on agriculture (Potts et al., 2010). Let's examine how pollinators and agriculture are impacted by climate change: ...
... Pollinators, particularly bees, play an indispensable role in supporting wild ecosystems [1] and agricultural production [2]. Honeybees often dominate the discourse on pollination, and their decline is covered in contemporary studies [3,4]. However, in tropical and subtropical regions worldwide, the stingless bees comprise a majority of all eusocial bees, both in abundance and diversity [5,6]. ...
Background
Stingless bees are vital pollinators and honey producers in the tropics. Research on stingless bees is generally underrepresented compared to the western honeybees, and while stingless bee studies from some regions are reported, there is a particular lack of reports on the species endemic to Sub-Saharan Africa. Since conventional entomological methods such as mark-recapture and radar harmonic tags suffer from limited observation counts and amount to a significant payload, fluorescent powder tagging offers a promising alternative to understanding their behavior. We deploy a hyperspectral fluorescence lidar monitors a 25-mm-wide transect in front of the hives.
Results
During a 1 day study at the International Stingless Bee Center, near Kakum National Park, Ghana, 17,862 insects were observed with the lidar, of which 7520 were tagged with fluorescent dyes. Approximately half of the bees from the selected hives were successfully tagged, with an estimated misclassification of 1%. According to our limited data, the observed species, Meliponula bocandei and the Dactylurina staudingeri exhibited different activity patterns. D. staudingeri displayed a half-hour longer active day, with clear crepuscular activity peaks. In contrast, M. bocandei activity was diurnal, with less pronounced crepuscular peaks.
Conclusions
We demonstrate how hyperspectral fluorescence lidar can monitor powder-tagged insects throughout the day. The monitored species revealed distinct activity patterns over the day. Our findings highlight the potential of this technology as a valuable tool for understanding insect behavior and environmental preferences of species, in situ, which could potentially give clues of response to climate changes of these critical species.
... Bees are critical to agricultural resilience by providing pollination services for a swathe of speciality crops (Klein et al. 2007, Potts et al. 2016, Knapp et al. 2017, Delaplane 2021. However, both wild and managed bees are threatened by interacting combinations of stressors, including forage loss, parasite pressures, and exposure to agrochemicals, including pesticides (Genersch et al. 2010, Pettis and Delaplane 2010, Potts et al. 2010, vanEngelsdorp and Meixner 2010, Goulson et al. 2015, Manley et al. 2015, Bird et al. 2021. Agricultural pesticides are known to interact in their toxicity, leading to suspicions that their dangers to bee pollinators are underestimated (Siviter et al. 2021). ...
Agrochemical exposure is a major contributor to ecological declines worldwide, including the loss of crucial pollinator species. In addition to direct toxicity, field-relevant doses of pesticides can increase species’ vulnerabilities to other stressors, including parasites. Experimental field demonstrations of potential interactive effects of pesticides and additional stressors are rare, as are tests of mechanisms via which pollinators tolerate pesticides. Here, we controlled honey bee colony exposure to field-relevant concentrations of 2 neonicotinoid insecticides (clothianidin and thiamethoxam) in pollen and simultaneously manipulated intracolony genetic heterogeneity. We showed that exposure increased rates of Varroa destructor (Anderson and Trueman) parasitism and that while increased genetic heterogeneity overall improved survivability, it did not reduce the negative effect size of neonicotinoid exposure. This study is, to our knowledge, the first experimental field demonstration of how neonicotinoid exposure can increase V. destructor populations in honey bees and also demonstrates that colony genetic diversity cannot mitigate the effects of neonicotinoid pesticides.
... Esta crisis es causada por la degradación y fragmentación de los bosques, la introducción de especies invasoras no nativas, el aumento de patologías, así como el uso intensivo de pesticidas y el cambio climático (Beltrán & Traveset 2018). Aunque el impacto de esta crisis varía ampliamente a nivel regional, y no todas las especies de polinizadores se ven afectadas de la misma manera, la disminución del número de poliniza-dores, tanto individuales como de especies, es una de las consecuencias más recurrentes (Biesmeijer & al. 2006, Potts & al. 2010. ...
Plant-animal interactions mostly have mutual benefits, particularly pollination where the floral visitor collects food and thus contributes to the transport of pollen, in turn; these interactions contribute to the sustainability of biodiversity in ecosystems through the forest regeneration processes. The objective of this study was to identify floral visitors, particularly insects that visit the flowers of the species that inhabit the Ciudad Universi-taria campus of the National Autonomous University of Honduras. Observations of flowering plant species and their visitors were made for four years. 75 plant species and 237 plant-visitor interactions were reported, where Hymenoptera were the most frequent, particularly Apis mellifera (30 %) visiting herbaceous and tree species. The insects visited small and large flowers of pale colors, mostly herbaceous species represented in the families Asteraceae, Fabaceae, Acanthaceae, Bignoniaceae, Convolvulaceae and Euphorbiaceae. Tecoma stans, Veitchia merrillii, Melanthera nivea, Lantana camara, Parthenium hysterophorus, Turnera scabra, Baltimora erecta, Simarouba glauca and Muntingia calabura presented the highest number of interactions. Apis mellifera is an introduced species that has been recorded in various ecosystems. The high frequency of floral visitors in some herbaceous and arboreal plants was due to the availability of floral resources such as pollen and nectar, since these species bloom almost all year round. Certainly, that the native and introduced flora contribute to the maintenance of biodiversity in these dry forest fragments in Tegucigalpa through biotic interactions.
... However, in recent times, there has been a growing concern about declines in the natural populations of honeybees. Among different factors responsible for bee decline are habitat loss and fragmentation, chemical intensive agriculture, invasive species and climate change [9]. Climate change appears to be a major concern for agriculture in general and may also have worrying implications for beekeeping. ...
With the increasing loss of insect species, their ecosystem services such as pollination of plants and pest control are also under threat. This means that more intense monitoring is needed, but this poses many challenges: Collecting is comparatively easy and carried out at many locations worldwide using standardized methods such as Malaise traps that preserve the specimens in ethanol. However, a comprehensive, systematic evaluation of these samples at the specimen-level is not yet possible due to the large number of specimens and the lack of taxonomic experts who can identify the specimens to species level. We thus here present a new mini-gripper for the automated handling of insects preserved in ethanol. The mini-gripper automatically picks insects from bulk samples as long as they are in the 7.5 mm–15 mm size range to be transferred to the DiversityScanner, where they are classified using a trained AI model. This automated approach is currently tested in an EU project to identify new invasive pests.
Introduction
Interactions between flowering plants and visiting wild bees are crucial for ensuring pollination and subsequent plant reproductive success. However, bee diversity in an area has rarely been recorded in relation to seed set in native plants. In this project, we investigated the effect of local wild bee communities on seed set in four common wild plant species.
Methods
Potted plants of Centaurea jacea, Cichorium intybus, Sinapis arvensis, and Salvia pratensis were placed for pollination experiments, in two distinct habitat types that we expected to show distinct bee communities, namely near-natural grassland and perennial wild flower strips, in Germany.
Results
Our results showed that near-natural grassland had a higher bee species richness and an increased seed set compared with flower strips that displayed a higher bee abundance in most study locations. Although we found effects of bee diversity on seed set, we did not detect a significant effect of bee abundance. Furthermore, the seed set in response to wild bee diversity differed across the plant species.
Discussion
We conclude that bee-friendly habitats ensure a high seed set in wild plants, but that the impact varies between different plant species.
Protecting diverse solitary ground-nesting bees remains a pivotal conservation concern. Ground-nesting bees are negatively impacted by anthropogenic land use change that often removes suitable nesting habitat from the landscape. Despite their enormous ecological and agricultural contributions to pollination, solitary, ground-nesting bees are often neglected, partly due to the significant obstacle of discovering exactly where these bees establish their nests. To address this limitation, we have developed a ‘community science’ project to map aggregations of ground-nesting bees globally. In certain locations, their abundances reach astounding levels, sometimes in the millions, but are scarcely known. Utilizing the iNaturalist platform, which permits geo-referencing of site observations and bee identification, we are providing public education and seeking public engagement to document bee aggregations in order to understand the nesting requirements of diverse species and open new opportunities for their conservation. Conservation priorities may then unequivocally be directed to areas of high species richness, nest densities, and nesting sites of rare bees. Such community-led efforts are vital for successful long-term management of native bees and the biotic and abiotic landscape data from nest-site localities can allow modeling to predict nest-site suitability and to readily test such predictions on the ground. Here, we summarize the progress, current limitations, and opportunities of using a global mapping project (GNBee) to direct conservation efforts and research toward solitary ground-nesting bees.
Floral nectar sugar composition is assumed to reflect the nutritional demands and foraging behaviour of pollinators, but the relative contributions of evolutionary and abiotic factors to nectar sugar composition remain largely unknown across the angiosperms. We compiled a comprehensive dataset on nectar sugar composition for 414 insect-pollinated plant species across central Europe, along with phylogeny, paleoclimate, flower morphology, and pollinator dietary demands, to disentangle their relative effects. We found that phylogeny was strongly related with nectar sucrose content, which increased with the phylogenetic age of plant families, but even more strongly with historic global surface temperature. Nectar sugar composition was also defined by floral morphology, though it was not related to our functional measure of pollinator dietary demands. However, specialist pollinators of current plant-pollinator networks predominantly visited plant species with sucrose-rich nectar. Our results suggest that both physiological mechanisms related to plant water balance and evolutionary effects related to paleoclimatic changes have shaped floral nectar sugar composition during the radiation and specialisation of plants and pollinators. As a consequence, the high velocity of current climate change may affect plant-pollinator interaction networks due to a conflicting combination of immediate physiological responses and phylogenetic conservatism.
In recent years, managed honey bee colonies have been suffering from an increasing number of biotic and abiotic stressors, resulting in numerous losses of colonies worldwide. A pan-European study, EPILOBEE, estimated the colony loss in Belgium to be 32.4% in 2012 and 14.8% in 2013. In the current study, absolute viral loads of four known honey bee viruses (DWV-A, DWV-B, AmFV, and BMLV) and three novel putative honey bee viruses (Apis orthomyxovirus 1, apthili virus, and apparli virus) were determined in 300 Flemish honey bee samples, and associations with winter survival were determined. This revealed that, in addition to the known influence of DWV-A and DWV-B on colony health, one of the newly described viruses (apthili virus) shows a strong yearly difference and is also associated with winter survival. Furthermore, all scrutinized viruses revealed significant spatial clustering patterns, implying that despite the limited surface area of Flanders, local virus transmission is paramount. The vast majority of samples were positive for at least one of the seven investigated viruses, and up to 20% of samples were positive for at least one of the three novel viruses. One of those three, Apis orthomyxovirus 1, was shown to be a genuine honey bee-infecting virus, able to infect all developmental stages of the honey bee, as well as the Varroa destructor mite. These results shed light on the most prevalent viruses in Belgium and their roles in the winter survival of honey bee colonies.
IMPORTANCE
The western honey bee ( Apis mellifera ) is a highly effective pollinator of flowering plants, including many crops, which gives honey bees an outstanding importance both ecologically and economically. Alarmingly high annual loss rates of managed honey bee colonies are a growing concern for beekeepers and scientists and have prompted a significant research effort toward bee health. Several detrimental factors have been identified, such as varroa mite infestation and disease from various bacterial and viral agents, but annual differences are often not elucidated. In this study, we utilize the viral metagenomic survey of the EPILOBEE project, a European research program for bee health, to elaborate on the most abundant bee viruses of Flanders. We complement the existing metagenomic data with absolute viral loads and their spatial and temporal distributions. Furthermore, we identify Apis orthomyxovirus 1 as a potentially emerging pathogen, as we find evidence for its active replication honey bees.
There are widespread public efforts to conserve wildlife in urbanized landscapes via the installation of nursery-grown plants that support Lepidoptera taxa. Insecticides are commonly used during nursery production to suppress key plant pests, and many products have extended periods of toxicity and affect a wide range of herbivore taxa. While there are plentiful toxicological data on bee species, predominantly the Western honey bee (Apis mellifera L.), little is known about how insecticides affect nonpest lepidopterans. Lepidoptera has different modes of exposure (e.g., leaf-feeding) and differences in susceptibility to insecticide target sites compared to bees. Consequently, many products compatible with bee conservation pose an uncertain risk to nonpest lepidopterans and thus may represent an under-recognized conflict with conservation efforts. Using the monarch butterfly (Danaus plexippus, L.), tropical milkweed (Asclepias curassavica, L.), and oleander aphid (Aphis nerii, Fonscolombe, 1841) system, we conducted leaf and whole-plant feeding assays to evaluate effects of acute and chronic monarch exposure to industry standard and alternative reduced-risk insecticides used during nursery production. We also evaluated the efficacy of these insecticides against their target pest, the oleander aphid. Our results indicate that insecticides used to control pests on ornamental milkweed can cause monarch larval mortality up to 4 wk after treatment application. Furthermore, the duration of aphid suppression is often shorter than the duration of adverse effects on monarchs. This study demonstrates a conflict between insect pest management and Lepidoptera conservation during ornamental plant production and has implications for the conservation value of ornamentals after retail sale.
At least 87% of angiosperm species require animal vectors for their reproduction, while more than two-thirds of major global food crops depend on zoogamous pollination. Pollinator insects are a wide variety of organisms that require diverse biotic and abiotic resources. Many factors have contributed to a serious decrease in the abundance of populations and diversity of pollinator species over the years. This decline is alarming, and the Euro-pean Union has taken several actions aimed at counteracting it by issuing new conservation policies and standardizing the actions of member countries. In 2019, the European Green Deal was presented, aiming to restore 100% of Europe's degraded land by 2050 through financial and legislative instruments. Moreover, the Common Agricultural Policies have entailed greening measures for the conservation of habitats and beneficial species for more than 10 years. The new CAP (CAP 23-27) reinforces conservation objectives through strategic plans based on eco-schemes defined at the national level by the member countries, and some states have specifically defined eco-schemes for pollinator conservation. Here, we review the framework of EU policies, directives , and regulations, which include measures aimed at protecting pollinators in agricultural, urban, and peri-urban environments. Moreover, we reviewed the literature reporting experimental works on the environmental amelioration for pollinators, particularly those where CAP measures were implemented and evaluated, as well as studies conducted in urban areas. Among CAP measures, several experimental works have considered the sowing and management of entomophilous plants and reported results important for environmental ameliora-tions. Some urban, peri-urban and wasteland areas have been reported to host a considerable number of polli-nators, especially wild bees, and despite the lack of specific directives, their potential to contribute to pollinator conservation could be enhanced through targeted actions, as highlighted by some studies.
After regulation of pesticides, determination of their persistence in the environment is an important indicator of effectiveness of these measures. We quantified concentrations of two types of systemic insecticides, neonicotinoids (imidacloprid, acetamiprid, clothianidin, thiacloprid, and thiamethoxam) and butenolides (flupyradifurone), in off‐crop nontarget media of hummingbird cloacal fluid, honey bee ( Apis mellifera ) nectar and honey, and wildflowers before and after regulation of imidacloprid on highbush blueberries in Canada in April 2021. We found that mean total pesticide load increased in hummingbird cloacal fluid, nectar, and flower samples following imidacloprid regulation. On average, we did not find evidence of a decrease in imidacloprid concentrations after regulation. However, there were some decreases, some increases, and other cases with no changes in imidacloprid levels depending on the specific media, time point of sampling, and site type. At the same time, we found an overall increase in flupyradifurone, acetamiprid, thiamethoxam, and thiacloprid but no change in clothianidin concentrations. In particular, flupyradifurone concentrations observed in biota sampled near agricultural areas increased twofold in honey bee nectar, sevenfold in hummingbird cloacal fluid, and eightfold in flowers after the 2021 imidacloprid regulation. The highest residue detected was flupyradifurone at 665 ng/mL (parts per billion [ppb]) in honey bee nectar. Mean total pesticide loads were highest in honey samples (84 ± 10 ppb), followed by nectar (56 ± 7 ppb), then hummingbird cloacal fluid (1.8 ± 0.5 ppb), and least, flowers (0.51 ± 0.06 ppb). Our results highlight that limited regulation of imidacloprid does not immediately reduce residue concentrations, while other systemic insecticides, possibly replacement compounds, concurrently increase in wildlife. Environ Toxicol Chem 2024;00:1–12. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
Compared the composition of Belgian bumblebee faunas before and since 1950. Of 31 species, 14, mostly leguminous and composite foragers from open areas, became very scarce. The relative abundance of 7 species did not change. The relative abundance of 5 forest species has strongly increased. The Belgian potential annual bumblebee population can be estimated at 2.9 × 109 specimens. The decrease of leguminous cultures can explain a reduction of 1.3 × 109 specimens. Modifications of grassland flora due to nitrogenous fertilization and herbicide practices can explain a decrease of 0.15-0.45 × 109 specimens. The strong increase of forest area can explain the increase of forest species. -from English summary
The Report “A metagenomic survey of microbes in honey bee colony collapse disorder” (D. L. Cox-Foster et al. , 12 October 2007, p. [283][1]) identified Israeli acute paralysis virus (IAPV) as a putative marker for colony collapse disorder (CCD). It also purports to show a relationship between U.
First estimation of faunistic drift by bumblebees of Belgium (Hymenoptera, Apidae).
Summary. The authors compare the composition of belgian bumblebee faunas before and since 1950. Of 31 species, 14 became very scarse, mostly Leguminous and Composites foragers from open areas . The relative abundance of 7 species did not change. The relative abundance of 5 forest species has strongly increased. The belgian potential annual bumblebee population can be estimated at 2.9x10E9 specimens. The decrease of leguminous cultures can explain the disparition of approximately 1.3x10E9 specimens. The modifications of grassland flora due to nitrogenous fertilization and herbicide practices can explain a decrease of 0.15 to 0.45x10E9 specimens. The strong increase of forest area (+26% for the only Wallonie region) can explain the increase of forest species. Other factors (entomological collection, destruction by cars, insecticides, rasing of road sides) seem to be negligeable.
We review evidence from around the world for bumblebee declines and review management to mitigate threats. We find that there is evidence that some bumblebee species are declining in Europe, North America, and Asia. People believe that land-use changes may be having a negative effect through reductions in food plants in many parts of the world, but that other factors such as pathogens may be having a stronger effect for a few species in some regions (especially for Bombus s. str. in North America). Evidence so far is that greater susceptibility to land-use change is associated world-wide with small climatic ranges, range edges, and late-starting colony-development cycles. More evidence is needed on the roles of pollen specialization, nest sites, hibernation sites, and pesticides. It is still too early to assess the success of schemes aimed at improving forage in agricultural and conservation areas. However, schemes aimed at raising public awareness have been very successful. Until proven safe, we recommend that live bumblebees should not be moved across continents or oceans for commercial pollination.
Most ecological processes and interactions depend on scales much larger than a single habitat, and therefore it is important to link spatial patterns and ecological processes at a landscape scale. Here, we analyzed the effects of landscape context on the distribution of bees (Hymenoptera: Apoidea) at multiple spatial scales with respect to the following hypotheses: (1) Local abundance and diversity of bees increase with increasing proportion of the surrounding seminatural habitats. (2) Solitary wild bees, bumble bees, and honey bees respond to landscape context at different spatial scales. We selected 15 landscape sectors and determined the percentage of seminatural habitats and the diversity of habitat types at eight spatial scales (radius 250-3000 m) by field inspections and analyses of vegetation maps using two Geographic Information Systems. The percentage of semi- natural habitats varied between 1.4% and 28%. In the center of each landscape sector a patch of potted flowering plants (four perennial and two annual species) was placed in the same habitat type, a grassy field margin adjacent to cereal fields. In all, 865 wild bee individuals and 467 honey bees were observed and an additional 475 individuals were caught for species identification. Species richness and abundance of solitary wild bees showed a close positive correlation with the percentage of seminatural habitats at small scales up to 750 m, whereas bumble bees and honey bees did not respond to landscape context at these scales. In contrast, honey bees were correlated with landscape context at large scales. The densities of flower-visiting honey bees even increased with decreasing proportion of seminatural habitats at a radius of 3000 m. We are not aware of any empirical studies showing contrasting foraging patterns related to landscape context at different spatial scales. We conclude (1) that local landscape destruction affects solitary wild bees more than social bees, possibly changing mutualistic plant-pollinator and competitive wild bees- honey bees interactions and (2) that only analyses of multiple spatial scales may detect the importance of the landscape context for local pollinator communities.
We review direct and indirect impacts of invasive alien species (focussing on plants and insects) on native bees worldwide.
Although there is a rapidly growing body of research into the effects of invasive alien plants on native plant pollination
via disruption of native mutualisms, there has been little research on the impacts of invasive alien plants directly on bees.
Such impacts are likely to vary according to the taxon of plant, the functional specificity of the native bees, and ecosystem
context. Conversely, there have been more attempts to document impacts of invasive alien social bees on native bees. Most
of these studies only indirectly evaluate competition for resources, have focused on a few native species and findings are
sometimes contradictory. However, some studies showed strong negative impacts, suggesting that effects might be species-specific.
Additionally, pathogen spillover and reproductive disruption due to interspecific mating has been demonstrated among some
closely related taxa. Where we lack unequivocal evidence for impacts however, this should not be interpreted as lack of effect.
We recommend that future studies are robustly designed and consider impacts on genetic, species (particularly solitary bees)
and ecosystem biodiversity.
Summary 1. We assess the importance of body mass and the minimum ambient temperature at which foraging occurs in determining the warm-up rates and thoracic temperatures in flight at an air temperature of 22 °C of 55 species of bee (Hymenoptera: Apoidea) from six families adapted to a variety of thermal environments. 2. To control for the effects of taxonomic differences in the relationships between these variables, we use multiple regression incorporated in the phylogen- etic regression method developed by Grafen (1989). 3. The prediction made by May (1976) that for very small heterotherms warm- up rate will correlate positively with body mass is confirmed when the effects of phylogeny and the thermal environment to which the bee is adapted have been controlled for. The relationship between warm-up rate and body mass within the Apoidea is thus not an extension to lower body masses of the relationship found for heterothermic vertebrates. 4. Having controlled for the effects of body mass in our analyses, we demonstrate that bees able to fly at lower ambient temperatures have higher thoracic temperatures and warm-up rates than bees adapted to wanner environ- ments. 5. There is some suggestion that kleptoparasitic bees, being freed from the need to forage in order to provision cells, have lower warm-up rates than provisioning species. 6. The significance of these relationships in the ecology of bees is discussed in relation to studies of body temperatures and warm-up rates in bees and other insects.
There is a voluminous literature on pollination and dispersal, very
little of which deals with the consequences of reproductive failure and
its most extreme consequence: extinction. The risk of plant extinctions
can be assessed by considering the probability of dispersal or
pollinator failure, reproductive dependence on the mutualism and
demographic dependence on seeds. Traits for ranking species rapidly
according to these three criteria are indicated. Analysis of case
studies suggests that plants often compensate for high risk in one of
the three categories by low risk in another. For example,
self-incompatible plants with rare specialist pollinators often
propagate vegetatively. Some systems, including elements of the Cape
flora and lowland tropical rain forest, lack compensatory traits and the
risk of plant extinction from failed mutualism is high. 'What escapes
the eye, however, is a much more insidious kind of extincnction: the
extinction of ecological interactions' Janzen (1974).
Growing evidence indicates that European managed honey bees are in decline, but information for Europe remains patchy and localized. Here we compile data from 18 European countries to assess trends in the number of honey bee colonies and beekeepers between 1965 and 2005. We found consistent declines in colony numbers in central European countries and some increases in Mediterranean countries. Beekeeper numbers have declined in all of the European countries examined. Our data support the view that honey bees are in decline at least in some regions, which is probably closely linked to the decreasing number of beekeepers. Our data on colony numbers and beekeepers must, however, be interpreted with caution due to different approaches and socioeconomic factors in the various countries, thereby limiting their comparability. We therefore make specific recommendations for standardized methodologies to be adopted at the national and global level to assist in the future monitoring of honey bees.
Plant-animal mutualistic networks can be described as bipartite graphs depicting the interactions between two distinct sets: plants and animals. These mutualistic networks have been found to be highly structured. Specifically, they show a nested pattern in which specialists interact with proper subsets of the species generalists interact with. This pattern is important for understanding coevolution in species-rich communities which can be reduced neither to pairs of coevolving species nor to diffuse, randomly-interacting assemblages. We discuss the dynamic implications of network structure from the points of view of coevolution, community ecology, and conservation biology.
Mean global temperatures have risen this century, and further warming is predicted to continue for the next 50-100 years. Some migratory species can respond rapidly to yearly climate variation by altering the timing or destination of migration, but most wildlife is sedentary and so is incapable of such a rapid response. For these species, responses to the warming trend should be slower, reflected in poleward shifts of the range. Such changes in distribution would occur at the level of the population, stemming not from changes in the pattern of indivduals' movements, but from changes in the ratios of extinctions to colonizations at the northern and southern boundaries of the range. A northward range shift therefore occurs when there is net extinction at teh southern boundary or net colonization at the northern boundary. However, previous evidence has been limited to a single species or to only a portion of the species' range. Here we provide the first large-scale evidence of poleward shifts in entire species' ranges. In a sample of 35 non-migratory European butterflies, 63% have ranges that have shifted to the north by 35-240 km during this century, and only 3% have shifted to the south.
Agricultural intensification poses a serious threat to biodiversity as a consequence of increased land-use intensity, decreased landscape heterogeneity and reduced habitat diversity. Although there is interest in the preservation of total species richness of an agricultural landscape (gamma diversity), the effects of intensification have been assessed primarily by species richness at a local scale (alpha diversity). This ignores species richness between local communities (beta diversity), which is an important component of total species richness.
In this study, measures of land-use intensity, landscape structure and habitat diversity were related to gamma, alpha and beta diversity of wild bees (Apoidea), carabid beetles (Carabidae), hoverflies (Syrphidae), true bugs (Heteroptera) and spiders (Araneae) within 16 local communities in 24 temperate European agricultural landscapes.
The total landscape species richness of all groups was most strongly affected by increased proximity of semi-natural habitat patches. Bees also decreased in landscapes with a high intensity of farmland management, demonstrating additive effects of both factors.
Separating total species diversity into components, the decrease in total species richness could be attributed primarily to a decrease in species diversity between local communities. Species richness of the local communities of all investigated groups decreased with increasing land-use intensity and, in the case of spiders, decreasing proximity of the semi-natural habitat patches.
The effect of increased habitat diversity appeared to be of secondary importance to total species richness but caused a shift in the relative contribution of alpha and beta diversity towards the latter.
Synthesis and applications. This study demonstrates that the effects of agricultural change operate at a landscape level and that examining species diversity at a local level fails to explain the total species richness of an agricultural landscape. The coincidence of patterns of beta diversity with those of gamma diversity emphasizes that such information is of crucial importance for the implementation and evaluation of restoration programmes aiming to restore sustainable countryside diversity. As local extinction processes in highly fragmented landscapes shape biodiversity, priority should be given to the conservation of diverse agricultural landscape remnants in Europe.
In 1996, a naturally occurring nest of an introduced bumblebee, Bombus terrestris L., was found in Monbetsu in the Hidaka region of southern Hokkaido, indicating that it had become naturalized in Japan. In this region, monitoring of B. terrestris has been continued at two sites. The numbers of B. terrestris captured or observed have increased rapidly during the eight years since the evidence of its naturalization was found. Seasonally, the queens of naturalized B. terrestris have appeared as early as mid-April each spring. Queens were observed continuously during the period from April to October, workers from May to October, and males from July to October. B. terrestris was shown to forage among various flowering plants, 40% −70% of the species of flowering plants upon which native bumblebees fed. Nine of ten natural nests of B. terrestris discovered during the study were found in abandoned underground rodent nests. The nest sites of this species were similar to those of B. hypocrita sapporoensis Cockerell, and B. diversus tersatus Smith. B. terrestris clearly has the potential to compete with native bumblebees for floral resources and nest sites. The mean number of new queens born in the colonies of B. terrestris was 4.4 times larger than that of the native bumblebees. This strongly suggested superior reproductive ability of B. terrestris compared with native bumblebees in the region.
Apiculture has been in decline in both Europe and the USA over recent decades, as is shown by the decreasing numbers of managed honey bee (Apis mellifera L.) colonies (Ellis et al., 2010; Potts et al., 2010). It therefore is crucial to make beekeeping a more attractive hobby and a less laborious profession, in order to encourage local apiculture and pollination. Apart from socio-economic factors, which can only be addressed by politicians, sudden losses of honey bee colonies have occurred, and have received considerable public attention. Indeed, in the last few years, the world's press has been full of eye catching but often uninformative headlines proclaiming the dramatic demise of the honey bee, a world pollinator crisis and the spectre of mass human starvation. "Colony Collapse Disorder" (CCD) in the USA has attracted great attention, and scientists there and in Europe are working hard to provide explanations for these extensive colony losses. Colony losses have also occurred elsewhere (Figs 1 and 2), but examination of the historical record shows that such extensive losses are not unusual (vanEngelsdorp and Meixner, 2009). African honey bees and Africanized ones in the Americas survive without Varroa destructor treatment, whilst the mite has not yet been introduced into Australia. This global picture indicates a central role of this particular ectoparasitic mite for colony losses.
We examined the effects of habitat fragmentation on the pollinator diversity and reproductive success of seven perennial plant species in renosterveld shrublands in South Africa. We sampled pollinators in small (0.5–2 ha), medium (3–10 ha), and large (>30 ha) habitat fragments during the peak flowering period in spring and summer. We also compared fruit set and seed set in the seven plant species on different-sized fragments. Hand-pollinated controls were used to determine pollination deficits in three species. Seed-germination studies were done on two species to determine the effect of reduced seed set on reproductive output. Overall, the species richness of bees, flies, and butterflies did not vary significantly among different-sized fragments. However, the abundance of particular species of bees and monkey beetles (Scarabaeidae: Hopliini) was significantly affected by fragment size, together with other factors such as vegetation cover and the ratio of grass to shrubs. Fragment size and distance to large remnants of vegetation had a significant influence on seed or fruit set in four of the seven plant species examined. One species failed to set any seed in small- and medium-sized fragments. Comparisons of fruit and seed set among hand-pollinated and naturally pollinated plants confirmed that seed set was pollinator-limited in the orchid Pterygodium catholicum. Our results suggest that perennial plant species respond in different ways to fragmentation, and that populations on small fragments do not always experience pollination deficits. Existing classifications of pollination systems, in relation to their vulnerability to fragmentation, do not adequately explain our results. We argue that there needs to be a greater focus on the habitat requirements of pollinators to predict the effects of habitat fragmentation on pollination systems and plant reproductive success.
Abstract 1. The small hive beetle, Aethina tumida, is a parasite of honeybee (Apis mellifera) colonies native to sub-Saharan Africa and has become an invasive species. In North America the beetle is now sympatric with bumblebees, Bombus, not occurring in its native range. Laboratory studies have shown that small hive beetles can reproduce in bumblebee colonies but it was not known whether infestations occur in the field.
2. For the first time, infestation of bumblebee colonies by small hive beetles was investigated in the field. Commercial Bombus impatiens colonies (n= 10) were installed in proximity to infested apiaries. Within 8 weeks, all colonies that were alive in the 5-week observation period (n= 9) became naturally infested with adult small hive beetles and successful small hive beetle reproduction occurred in five colonies.
3. In four-square choice tests, the beetles were attracted to both adult bumblebee workers and pollen from bumblebee nests, suggesting that these odours may serve as cues for host finding.
4. The data indicate that bumblebee colonies may serve as alternative hosts for small hive beetles in the field. To foster the conservation of these essential native pollinators, investigations on the actual impact of small hive beetles on wild bumblebee populations are suggested.
Pollen limitation on a plant community level has received little attention, although it might show which pollination-related traits may cause pollen limitation to vary among species. To address several central questions in plant reproductive biology, we investigated pollen limitation in 11 plant species, including visitation and specialisation levels of all species. The female reproductive success of most species within the studied plant community was not pollen limited, but a general tradeoff between seed production and seed weight occurred as a response to supplemental pollination. In contrast to general notion, we did not find that less visited species were most pollen limited. Instead, it appears that species with high visitation rates were most pollen limited. Our study provided conflicting evidence to whether specialisation levels may affect the degree of pollen limitation within the study community. We discuss these findings in the context of recent reviews on the occurrence, causes and consequences of pollen limitation in plants. In particular, we propose that, although pollen limitation is an important phenomenon, 1) the majority of species within a plant community may not experience pollen limitation at a given moment, 2) that common notions of which plant species should experience pollen limited reproductive success do not hold true in the studied plant community, and 3) that offspring quality is as likely affected by surplus pollen loads as is the number of offspring.
To provide replicate samples of local bee populations in a nature preserve, light traps operated continuously on Barro Colorado
Island (BCI), Panama, collected bees for 17 years, including 10 years following invasion by African Apis mellifera. Honey bees appeared in light traps as the first swarms colonized the Panama Canal area. Their numbers followed seasonal
trends shown in inde-pendent studies, thus indicating bee abundance and activity in a large area. No measurable population-level
impact of competition between this invading honey bee and native bees, despite many demonstrations of resource competition
at flower patch and colony levels, changed annual abundances of all 15 native bee species. Native bee abundance did not decrease,
nor did native bees show substantial reciprocal yearly change with honey bee abundance. One strong negative correlation of
bee catches with an extremely rainy year was found. However, multiple regression using rainfall and honey bee abundance as
the independent variables showed that neither was responsible for bee population change over 17 years. Nearly half the native
species declined during a year that displayed peak honey bee number. That competition from honey bees on an island the size
of BCI was necessarily reduced below impact levels expected on the mainland is discussed using a model of resource and consumer
density, foraging range, and island size.
Bateman’s principle states that male fitness is usually limited by the number of matings achieved, while female fitness is
usually limited by the resources available for reproduction. When applied to flowering plants this principle leads to the
expectation that pollen limitation of fruit and seed set will be uncommon. However, if male searching for mates (including
pollen dissemination via external agents) is not sufficiently successful, then the reproductive success of both sexes (or
both sex functions in hermaphroditic plants) will be limited by number of matings rather than by resources, and Bateman’s
principle cannot be expected to apply. Limitation of female success due to inadequate pollen receipt appears to be a common
phenomenon in plants. Using published data on 258 species in which fecundity was reported for natural pollination and hand
pollination with outcross pollen, I found significant pollen limitation at some times or in some sites in 159 of the 258 species
(62%). When experiments were performed multiple times within a growing season, or in multiple sites or years, the statistical
significance of pollen limitation commonly varied among times, sites or years, indicating that the pollination environment
is not constant. There is some indication that, across species, supplemental pollen leads to increased fruit set more often
than increased seed set within fruits, pointing to the importance of gamete packaging strategies in plant reproduction. Species
that are highly self-incompatible obtain a greater benefit relative to natural pollination from artificial application of
excess outcross pollen than do self-compatible species. This suggests that inadequate pollen receipt is a primary cause of
low fecundity rates in perennial plants, which are often self-incompatible. Because flowering plants often allocate considerable
resources to pollinator attraction, both export and receipt of pollen could be limited primarily by resource investment in
floral advertisement and rewards. But whatever investment is made is attraction, pollinator behavioral stochasticity usually
produces wide variation among flowers in reproductive success through both male and female functions. In such circumstances
the optimal deployment of resources among megaspores, microspores, and pollinator attraction may often require more flowers
or more ovules per flower than will usually be fertilized, in order to benefit from chance fluctuations that bring in large
number of pollen grains. Maximizing seed set for the entire plant in a stochastic pollination environment might thus entail
a packaging strategy for flower number or ovule number per flower that makes pollen limitation of fruit or seed set likely.
Pollen availability may limit female success in individual flowers, entire plants (in a season or over a lifetime), or populations.
The appropriate level must be distinguished depending on the nature of the question being addressed.
The small hive beetle (SHB, Aethina tumida) is a parasite and scavenger of honeybee colonies. Here, we conducted laboratory experiments to investigate the potential of SHB as a vector of honeybee viruses. Using RT-PCR methods, Deformed Wing Virus (DWV) was detected in adult SHBs that: (1) were fed with dead workers with deformed wings, (2) were fed with DWV-positive brood, and (3) were associated with DWV-contaminated wax. SHB became significantly more often infected through feeding on virus infected workers, brood and the virus contaminated wax compared to pollen and the controls, where no infections were found. DWV was also detected in adult SHB after trophallaxis with infected workers. Further, among SHBs identified as DWV-positive, 40% of beetles carried negative stranded RNA of DWV, indicating virus replication. Our results suggest that SHB can be infected with honeybee viruses via food-borne transmission and have the potential of being a biological vector of honeybee viruses.
The density of wild honeybee colonies (Apis mellifera) in the African dry highland savannahs was estimated in three Nature Reserves in Gauteng, South Africa (Ezemvelo, Leeuwfontein,
Suikerbosrand) based on the genotypes of drones which were caught at drone congregation areas. Densities were estimated to
range between 12.4 and 17.6 colonies per square kilometer. In addition colony densities were estimated in two German National
parks (Müritz and Hochharz) and a commercial mating apiary. The density of colonies was significantly lower at the German
sampling sites with estimates of 2.4–3.2 colonies per square kilometer, which closely matches the nation-wide density of colonies
kept by beekeepers. This shows that the densities of colonies observed in wild populations under the harsh conditions of the
African dry savannahs exceeds that of Germany by far, in spite of intensive beekeeping. The intensity of apiculture in Europe
is therefore unlikely to compensate for the loss of habitats suitable for wild honeybees due to agriculture, forestry and
other cultivation of land.
Evidence for interspecific competition between honey bees and wild bees was studied on 15 calcareous grasslands with respect
to: (1) foraging radius of honey bees, (2) overlap in resource use, and (3) possible honey bee effects on species richness
and abundance of flower-visiting, ground-nesting and trap-nesting wild bees. The grasslands greatly differed in the number
of honey bee colonies within a radius of 2 km and were surrounded by agricultural habitats. The number of flower-visiting
honey bees on both potted mustard plants and small grassland patches declined with increasing distance from the nearest apiary
and was almost zero at a distance of 1.5–2.0 km. Wild bees were observed visiting 57 plant species, whereas honey bees visited
only 24 plant species. Percentage resource overlap between honey bees and wild bees was 45.5%, and Hurlbert’s index of niche
overlap was 3.1. In total, 1849 wild bees from 98 species were recorded on the calcareous grasslands. Neither species richness
nor abundance of wild bees were negatively correlated with the density of honey bee colonies (within a radius of 2 km) or
the density of flower-visiting honey bees per site. Abundance of flower- visiting wild bees was correlated only with the percentage
cover of flowering plants. In 240 trap nests, 1292 bee nests with 6066 brood cells were found. Neither the number of bee species
nor the number of brood cells per grassland was significantly correlated with the density of honey bees. Significant correlations
were found only between the number of brood cells and the percentage cover of shrubs. The number of nest entrances of ground-nesting
bees per square metre was not correlated with the density of honey bees but was negatively correlated with the cover of vegetation.
Interspecific competition by honey bees for food resources was not shown to be a significant factor determining abundance
and species richness of wild bees.
Comparison of the two flagship species of British bumblebee conservation (Bombus distinguendus and B. sylvarum) with a widespread, common, and more stable species (B. pascuorum) shows (1) that the two rarer and range-declining species in Britain had narrower (more specialized) climatic niches in western Europe even before their most severe declines, and (2) that the areas where they persist in Britain from 2000 onwards are closer climatically to the centres of their pre-decline west-European climatic niches than the areas from which they have been lost. Although data are available for few bumblebee species at present and further tests are needed, the first result supports earlier suggestions that it is bumblebee species with narrower climatic niches that are most vulnerable to decline. The second result supports the suggestion that it is in areas nearer the edges of their climatic niches where these species are most vulnerable to decline, although this can be ameliorated locally by higher food-resource levels. This is not to say that all patterns of bumblebee decline have been influenced by climatic niche, particularly in North America. Nonetheless, in Britain we find that even without climatic change, an interaction between climatic niche and food-plant reductions from land-use change retains the potential to explain at least some of the broader patterns of which species have declined, where they have declined, and how they have declined.
To better understand the dynamics of bee populations in crops, we assessed the effect of landscape context and habitat type on bee communities in annual entomophilous crops in Europe. We quantified bee communities in five pairs of crop-country: buckwheat in Poland, cantaloupe in France, field beans in the UK, spring oilseed rape in Sweden, and strawberries in Germany. For each country, 7–10 study fields were sampled over a gradient of increasing proportion of semi-natural habitats in the surrounding landscape. The CORINE land cover classification was used to characterize the landscape over a 3 km radius around each study field and we used multivariate and regression analyses to quantify the impact of landscape features on bee abundance and diversity at the sub-generic taxonomic level. Neither overall wild bee abundance nor diversity, taken as the number of sub-genera, was significantly affected by the proportion of semi-natural habitat. Therefore, we used the most precise level of the CORINE classification to examine the possible links between specific landscape features and wild bee communities. Bee community composition fell into three distinct groups across Europe: group 1 included Poland, Germany, and Sweden, group 2 the UK, and group 3 France. Among all three groups, wild bee abundance and sub-generic diversity were affected by 17 landscape elements including some semi-natural habitats (e.g., transitional woodland-shrub), some urban habitats (e.g., sport and leisure facilities) and some crop habitats (e.g., non-irrigated arable land). Some bee taxa were positively affected by urban habitats only, others by semi-natural habitats only, and others by a combination of semi-natural, urban and crop habitats. Bee sub-genera favoured by urban and crop habitats were more resistant to landscape change than those favoured only by semi-natural habitats. In agroecosystems, the agricultural intensification defined as the loss of semi-natural habitats does not necessarily cause a decline in evenness at the local level, but can change community composition towards a bee fauna dominated by common taxa.
Abstract Bees are generally regarded as beneficial insects for their role in pollination, and in the case of the honeybee Apis mellifera, for production of honey. As a result several bee species have been introduced to countries far beyond their home range, including A. mellifera, bumblebees (Bombus sp.), the alfalfa leafcutter bee Megachile rotundata, and various other solitary species. Possible negative consequences of these introductions include: competition with native pollinators for floral resources; competition for nest sites; co-introduction of natural enemies, particularly pathogens that may infect native organisms; pollination of exotic weeds; and disruption of pollination of native plants. For most exotic bee species little or nothing is known of these possible effects. Research to date has focused mainly on A. mellifera, and has largely been concerned with detecting competition with native flower visitors. Considerable circumstantial evidence has accrued that competition does occur, but no experiment has clearly demonstrated long-term reductions in populations of native organisms. Most researchers agree that this probably reflects the difficulty of carrying out convincing studies of competition between such mobile organisms, rather than a genuine absence of competitive effects. Effects on seed set of exotic weeds are easier to demonstrate. Exotic bees often exhibit marked preferences for visiting flowers of exotic plants. For example, in Australia and New Zealand many weeds from Europe are now visited by European honeybees and bumblebees. Introduced bees are primary pollinators of a number of serious weeds. Negative impacts of exotic bees need to be carefully assessed before further introductions are carried out.
1. When considered together, the diversity and abundance of biologically similar organisms (e.g. pollinators) within a community, are more powerful in assessing the effects of disruption than when taken separately. The log-normal model of abundance and diversity is illustrated as a tool in applied ecology. 2. Data were collected from sampling pollinating bees over 8 years in 13 blueberry fields in New Brunswick, Canada. These data were used to test the log-normality of the species diversity and abundance relationships with respect to the disruption of communities by applications of the insecticide fenitrothion to nearby forests. 3. Ecosystemic integrity (health) of the lowbush blueberry fields was assessed by using species diversity and abundance in Sugihara's (1980) sequential breakage model. This model was used to test the log-normality of data sets from fields which were affected and unaffected by fenitrothion. 4. On both spatial and temporal bases, fields unaffected by the pesticide fitted well to the log-normal model of species diversity and abundance, whereas affected fields departed from that pattern. Thus, the relationship is useful because the samples from fields affected by fenitrothion presumably represent compromised integrity and decline in ecosystemic health. 5. Shannon-Wiener's hierarchical diversity indices and Jaccard's indices of similarity were found to have little value in measuring ecosystemic health. For the former, none of the indices calculated showed any difference between communities with a log-normal pattern of species diversity and abundance, and those without it. Jaccard's index of similarity was low and similar in all the cases. 6. In general, ecosystemic health should not be narrowly assessed through biodiversity but must include taxonomic and population changes together. The log-normal relationship linking species diversity and abundance is an objective standard against which applied ecologists can test ecosystemic integrity, disruption, health, ill-health, and reconstitution.
Apis mellifera is composed of three evolutionary branches including mainly African (branch A), western and northern European (branch M), and southeastern European (branch C) populations. The existence of morphological clines extending from the equator to the Polar Circle through Morocco and Spain raised the hypothesis that the branch M originated in Africa. Mitochondrial DNA analysis revealed that branches A and M were characterized by highly diverged lineages implying very remote links between both branches. It also revealed that mtDNA haplotypes from lineages A coexisted with haplotypes M in the Iberian Peninsula and formed a south-north frequency cline, suggesting that this area could be a secondary contact zone between the two branches. By analyzing 11 populations sampled along a France-Spain/Portugal-Morocco-Guinea transect at 8 microsatellite loci and the DraI RFLP of the COI-COII mtDNA marker, we show that Iberian populations do not present any trace of 'africanization' and are very similar to French populations when considering microsatellite markers. Therefore, the Iberian Peninsula is not a transition area. The higher haplotype A variability observed in Spanish and Portuguese samples compared to that found in Africa is explained by a higher mutation rate and multiple and recent introductions. Selection appears to be the best explanation to the morphological and allozymic clines and to the diffusion and maintenance of African haplotypes in Spain and Portugal.
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Abstract We empirically assessed the long-term changes in the rare species assemblage of a Mediterranean flora, in terms of species life history traits, niche and biogeographic features, and taxonomic groups. We used a 115-year historical record of ca. 2100 plant species occurrences in a 6250 km2 region in Mediterranean France. Species were assigned to two classes of regional abundance for the years 1886 and 2001 (rare species, i.e. exhibiting one or two occurrences vs. nonrare species), and to three classes of abundance changes during 1886–2001 (decreasing/extinct, stable, increasing/immigrant). Then, we tested whether species regional abundance and species abundance change were related to their morphological and life-history traits (life form, perenniality, height, dispersal agent, pollination mode), niche and biogeographic features (habitat specialization, level of endemism, biogeographic origin) and taxonomic group. The regional assemblage of rare species was not biologically random and significantly changed between 1886 and 2001. Species classified as rare in 1886 had a significantly higher rate of extinction in the study region during 1886–2001. The highest rate of regression/extinction was found among hydrophyte and/or water-dispersed rare species, and among annual rare species. However, herbaceous perennial, tree and wind-dispersed rare species significantly increased in abundance during 1886–2001. Rare species with Eurosiberian distributions, occurring at the southern margin of their range in the study region, dramatically declined or went extinct in the region during 1886–2001; whereas rare species with Mediterranean affinities remained significantly stable. We also found strong evidence for taxonomic patterns in species abundance and abundance changes from 1886 to 2001. The long-term biological changes documented here in the rare species assemblage of a Mediterranean flora are consistent with the predicted consequences of climate and land use changes currently occurring in the Mediterranean Basin. With the potential decline or even extinction of entire taxa and the loss of southern ecotypes of widespread Eurosiberian species, both evolutionary history and speciation potential of the Mediterranean Region could be strongly altered in future decades.
The synergistic effect of a range of ergosterol-biosynthesis-inhibiting (EBI) fungicides and a pyrethroid insecticide was studied in the honeybee (Apis mellifera L.). Various EBI fungicides were combined separately with the pyrethroid lambda-cyhalothrin at ratios derived from their recommended application rates to represent tank-mixing in the field. The mixture was then applied topically to the thorax of honeybees, and mortality assessed 24 h post-treatment. All the fungicides tested increased the toxicity of lambda-cyhalothrin to honeybees. The fungicide propiconazole was found to have the strongest synergistic effect, decreasing the LD50 of lambda-cyalothrin from 68.0 ng bee−1 to 4.2 ng, thus having a synergistic ratio of 16.2. Hazard ratios were calculated for lambda-cyhalothrin and fungicide mixtures using a recommended application rate of 7.5 g a.i. ha−1. The hazard ratio for lambda-cyhalothrin alone was 110, but when mixed with fungicide synergists, the hazard ratio ranged from 366 with flutriafol to 1786 with propiconazole. A blank formulation of a fungicide (without the active ingredient prochloraz) had little effect on the toxicity of lambda-cyhalothrin, indicating that it is primarily the fungicide active ingredient that is responsible for the synergistic effect. The results are discussed in terms of the potential hazard posed by pesticide synergism to honeybees in the field.
We studied the spread of the newly introduced parasitic mite, Varma jacobsoni Oudemans, within California's population of the feral honey bee, Apis mellifera L., by examining worker bees taken from 208 colonies in 1990, 124 of which were examined again in 1993. The samples taken in 1990 did not contain V. jacobsoni mites. In 1993, 75% of the colonies examined in an area located near Sacramento, CA, no longer existed, and all surviving colonies were infested with V. jacobsoni. In an area located near the Californian central coast, 84% of the nest sites examined were occupied and few colonies contained detectable levels of V. jacobsoni. The probability of survival for colonies that have not survived a winter yet (founder colonies) has been previously reported to be low in areas with a temperate climate. Data collected in an area with a low level of Varroa mite infestation suggest that the probability of founder colony survival is higher in California with a mostly Mediterranean climate. The data collected in areas with a high level of Varroa mite infestation suggest that the parasite reduces the mean life span of feral honey bee colonies in California to go between 6 mo and 1 yr. The parasite was widely spread in areas with a high density of commercial colonies. This suggests that the fast spread of the parasite is caused mostly by migration of commercial colonies. We discuss the consequences of the decline of the feral honey bee population on pollination and on the invasion of California by Africanized bees.
In this article we focus on the vital ecological services provided by insects. We restrict our focus to services provided
by “wild” insects; we do not include services from domesticated or mass-reared insect species. The four insect services for
which we provide value estimates—dung burial, pest control, pollination, and wildlife nutrition—were chosen not because of
their importance but because of the availability of data and an algorithm for their estimation. We base our estimations of
the value of each service on projections of losses that would accrue if insects were not functioning at their current level.
We estimate the annual value of these ecological services provided in the United States to be at least $57 billion, an amount
that justifies greater investment in the conservation of these services.
The cause of colony collapse disorder remains unknown, although some possible explanations for the loss of honey bee colonies
can be ruled out.
Bees are major pollinators of Angiosperms and therefore their apparent decline is of importance for humans and biodiversity. We synthesise results of 12 recent reviews to provide a global picture of the threats they face. Habitat loss is the major threat to bee diversity, whilst invasive species, emerging diseases, pesticide use, and climate change also have the potential to impact bee populations. We suggest that future conservation strategies need to prioritise (i) minimising habitat loss, (ii) making agricultural habitats bee-friendly, (iii) training scientists and the public in bee taxonomy and identification, (iv) basic autecological and population genetic studies to underpin conservation strategies, (v) assessing the value of DNA barcoding for bee conservation, (vi) determining the impact of invasive plants, animals, parasites and pathogens, and (vii) integrating this information to understand the potential impact of climate change on current bee diversity.
Developing tools for rapid assessment of introduced species impacts is one of the most important challenges in invasion ecology. Most assessments of impact rely on correlational data or other indirect measures. Yet few studies have evaluated invasion effects using multiple, simultaneously applied monitoring and experimental approaches, in order to compare easily obtained metrics with more difficult but direct measures of reproductive success or population dynamics. In this study, I use data from an experimental test of introduced honey bee (Apis mellifera) impacts on native bumble bees (Bombus spp.) to address two major questions: 1) how well did observational data on niche overlap and spatial correlations between Apis and Bombus predict the results of experimental tests of competitive effects? and 2) how well did effects of the experimental Apis manipulations on Bombus foragers, which are easy to observe, predict changes in reproductive success of colonies, which are difficult to measure? Niche overlap between Apis and Bombus varied substantially, but increased to levels as high as 80–90% during periods of resource scarcity. Correlations between numbers of Apis foragers and numbers of Bombus foragers were also highly variable, but I detected a significant negative relationship in only one of the seven months observed. In contrast, the experimental results showed that mean numbers of Bombus foragers observed on a given transect increased significantly with greater distance from introduced Apis colonies. Of these three measures (niche overlap, correlations in abundances, and effects of experimental introductions), only the experimental data on forager abundances accurately estimated competitive effects on colony reproductive success previously reported for the same experiment, and the correlational data in particular completely failed to predict the effects observed in the experimental study. This work suggests that great caution is warranted in making assessments of invasion impact on the basis of spatial or temporal correlations between invasive and native species. Thus, investing in even small and limited experimental studies may be more valuable than extensive observational work in quantifying invasion impacts.
s Abstract Bees are generally regarded as beneficial insects for their role in pol-lination, and in the case of the honeybee Apis mellifera, for production of honey. As a result several bee species have been introduced to countries far beyond their home range, including A. mellifera, bumblebees (Bombus sp.), the alfalfa leafcutter bee Megachile rotundata, and various other solitary species. Possible negative conse-quences of these introductions include: competition with native pollinators for floral resources; competition for nest sites; co-introduction of natural enemies, particularly pathogens that may infect native organisms; pollination of exotic weeds; and disrup-tion of pollination of native plants. For most exotic bee species little or nothing is known of these possible effects. Research to date has focused mainly on A. mellifera, and has largely been concerned with detecting competition with native flower visitors. Considerable circumstantial evidence has accrued that competition does occur, but no experiment has clearly demonstrated long-term reductions in populations of native or-ganisms. Most researchers agree that this probably reflects the difficulty of carrying out convincing studies of competition between such mobile organisms, rather than a genuine absence of competitive effects. Effects on seed set of exotic weeds are easier to demonstrate. Exotic bees often exhibit marked preferences for visiting flowers of exotic plants. For example, in Australia and New Zealand many weeds from Europe are now visited by European honeybees and bumblebees. Introduced bees are primary pollinators of a number of serious weeds. Negative impacts of exotic bees need to be carefully assessed before further introductions are carried out.
To counteract the decline of pollinators in Europe, conservation strategies traditionally focus on enhancing the local availability of semi-natural habitats, as supported by the European Union's Common Agriculture Policy. In contrast, we show that densities of bumblebees, an important pollinator group in agroecosystems, were not determined by the proportion of semi-natural habitats in agricultural landscapes. Instead, bumblebee densities were positively related to the availability of highly rewarding mass flowering crops (i.e. oilseed rape) in the landscape. In addition, mass flowering crops were only effective determinants of bumblebee densities when grown extensively at the landscape scale, but not at smaller local scales. Therefore, future conservation measures should consider the importance of mass flowering crops and the need for management schemes at landscape level to sustain vital pollination services in agroecosystems.
Despite ongoing concerns and controversy over a putative ‘global pollination crisis’ there is little information on the response of bees, the most important group of pollinators, to land‐use change. In particular, there are no published studies of the effects of tropical forest fragmentation on entire bee communities.
We examined bee community responses to forest fragment size, shape, isolation and landscape context (forest variables) by sampling foraging bees at ground level using aerial netting within, and in pastures adjacent to, 22 forest fragments ranging in area from c. 0·25 ha to 230 ha, in southern Costa Rica. We sampled each site 13 times in total, in both wet and dry seasons.
Although there were no effects of forest variables on bee diversity and abundance, we did find strong changes in bee community composition. In particular, tree‐nesting meliponines (social stingless bees) were associated with larger fragments, smaller edge:area ratios and greater proportions of forest surrounding sample points, while introduced Apis showed opposite patterns.
Community composition was also strikingly different between forests and pastures, despite their spatial proximity. In forests, even in the smallest patches, meliponines comprised a much larger proportion of the apifauna, and orchid bees (euglossines) were common. In pastures, Apis was much more abundant and no euglossine bees were found.
These results agree broadly with other studies that have found contrasting responses to habitat fragmentation from different bee groups. Conserving meliponine bees, important for pollination of coffee and other crops, and euglossine bees, critical in long‐distance pollen transport, will require forest.
Synthesis and applications . In the first study of the effects of tropical forest fragmentation on entire understorey bee assemblages, we found bee community resilience to land‐use change, as deforested sites and small forest fragments can have a diverse component of bees. While bees as a whole show some degree of resilience to land‐use change, there are taxon‐specific responses and, in our study area, there is clear value to conserving native forest, particularly for the ecologically and economically important meliponine and euglossine bees.
Pollinators are traditionally thought to perceive non-flowering crop fields as hostile landscape matrix. In this study, we show that landscapes composed of higher proportions of organic crop fields support more bee species at greater abundances in fallow strips. An increase in organic cropping in the surrounding landscape from 5% to 20% enhanced bee species richness in fallow strips by 50%, density of solitary bees by 60% and bumble bee density by 150%. Bee species richness and bumble bee density responded strongest to organic cropping in landscape sectors with 500 m radius, solitary bee density in landscape sectors with 250 m radius. The most likely source of these results is that crop and noncrop habitats are strongly connected via bee foraging at the landscape scale. It seems likely that bees depending on nesting sites in fallow strips benefited from the more abundant flower resources provided by broadleaved weeds in organic crop fields. We conclude that the incorporation of organic crop fields into conventionally managed agricultural landscapes can provide food resources needed to sustain greater pollinator species richness in noncrop habitats.
Numerous studies suggest that honeybees may compete with native pollinators where introduced as non-native insects. Here we
examine evidence for competition between honeybees and four bumblebee species in Scotland, a region that may be within the
natural range of honeybees, but where domestication greatly increases the honeybee population. We examined mean thorax widths
(a reliable measure of body size) of workers of Bombus pascuorum, B.lucorum, B.lapidarius and B.terrestris at sites with and without honeybees. Workers of all four species were significantly smaller in areas with honeybees. We suggest
that reduced worker size is likely to have implications for bumblebee colony success. These results imply that, for conservation
purposes, some restrictions should be considered with regard to placing honeybee hives in or near areas where populations
of rare bumblebee species persist.
Bumblebees are important pollinators of many crops and wild flowers and there are both conservation and economic reasons for taking action to assess the impact of pesticides on bumblebees. Pesticide risk assessments for honeybees are based on hazard ratios which rely on application rates and toxicity data and are unlikely to be appropriate for bumblebees. Bumblebees are active at different times and on different crop species and are, therefore, likely to have different exposure profiles. Unlike honeybees, deaths of bumblebees due to pesticides are unlikely to be reported, since the bees are not kept domestically and will die in small numbers. This paper highlights the differences in the potential risk posed by pesticides to bumblebees from that of honeybees. This is based on their exposure through use of crops and flowering weeds and on available data on toxicity of pesticides. This information is also intended as a source document for information on the foraging behavior and phenology of bumblebees for use in risk assessment for pesticides.
Pesticides are an important potential cause of biodiversity and pollinator decline. Little is known about the impacts of pesticides on wild pollinators in the field. Insect pollinators were sampled in an agricultural system in Italy with the aim of detecting the impacts of pesticide use. The insecticide fenitrothion was over 150 times greater in toxicity than other pesticides used in the area, so sampling was set up around its application. Species richness of wild bees, bumblebees and butterflies were sampled at three spatial scales to assess responses to pesticide application: (i) the ‘field’ scale along pesticide drift gradients; (ii) the ‘landscape’ scale sampling in different crops within the area and (iii) the ‘regional’ scale comparing two river basins with contrasting agricultural intensity. At the field scale, the interaction between the application regime of the insecticide and the point in the season was important for species richness. Wild bee species richness appeared to be unaffected by one insecticide application, but declined after two and three applications. At the landscape scale, the species richness of wild bees declined in vine fields where the insecticide was applied, but did not decline in maize or uncultivated fields. At the regional scale, lower bumblebee and butterfly species richness was found in the more intensively farmed basin with higher pesticide loads. Our results suggest that wild bees are an insect pollinator group at particular risk from pesticide use. Further investigation is needed on how the type, quantity and timing of pesticide application impacts pollinators.
We assessed national scale changes in the forage plants of bumblebees in Britain, as a means of providing quantitative evidence for the likely principal cause of declines in bumblebee species. We quantified the relative value of native and long-established plant species as forage (nectar and pollen) resources for bumblebees by collating visitation data from 14 field sites across Britain. Twentieth Century changes in range and frequency of these forage plants were assessed using data from the New Atlas of the British and Irish Flora (1930–1969 to 1987–1999) and the Countryside Surveys of Britain (1978–1998). Forage plants declined in both large-scale range and local-scale frequency between the two survey periods. These changes were of greater magnitude than changes in other native plant species, reflecting serious reductions in quality of foraging habitats for bees as well as a general decline in insect-pollinated plants. Seventy-six percent of forage plants declined in frequency within 1-km squares, including those (e.g. Trifolium pratense) of particular value for threatened bumblebee species. We consider how our findings relate to other recorded changes in the British flora, how they may help to explain declines in bumblebees and how they could contribute to a conservation strategy.
Organic farming is predicted to enhance diversity in agroecosystems. This study addresses the question of whether the often observed positive effect of organic farming on arable weed and pollinator diversity results in a significant shift in arable weed community structure towards a higher proportion of insect pollinated species in organic crop fields. To examine whether plant community patterns were consistent with this hypothesis, arable weed communities were compared with respect to the type of pollination (i.e. insect pollination versus non-insect pollination) in the edges and centres of 20 organic and 20 conventional wheat fields. Plant species numbers of both pollination types were much higher in organic than in conventional fields and higher in the field edge than in the field centre. A comparison of the proportions of both pollination types to all plant species revealed that the relative number of insect pollinated species was higher in organic than in conventional fields and higher at the field edge than in the field centre, whereas the relative number of non-insect pollinated species was higher in conventional fields and in the field centre. Our results show that insect pollinated plants benefit disproportionately from organic farming, which appeared to be related to higher pollinator densities in organic fields, whereas in the centres of conventional fields non-insect pollinated plants dominate presumably due to a limitation of pollinators. Hence, disruption of plant-pollinator interactions due to agricultural intensification may cause important shifts in plant community structure.