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Reducing the abundance of leafhoppers and thrips in a northern California organic vineyard through maintenance of full season floral diversity with summer cover crops
Abstract
1 Maintenance of floral diversity throughout the growing season in vineyards in the form of summer cover crops of buckwheat ( Fagopyrum esculentum Moench) and sunflower ( Helianthus annus Linnaeus), had a substantial impact on the abundance of western grape leafhoppers, Erythroneura elegantula Osborn (Homoptera: Cicadellidae), and western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), and associated natural enemies.
2 During two consecutive years, vineyard systems with flowering cover crops were characterized by lower densities of leafhoppers and thrips, and larger populations and more species of general predators, including spiders.
3 Although Anagrus epos Girault (Hymenoptera: Mymaridae), the most important leafhopper parasitoid, achieved high numbers and inflicted noticeable mortality of grape leafhopper eggs, no differences in egg parasitism rates were observed between cover cropped and monoculture systems.
4 Mowing of cover crops forced movement of Anagrus and predators to adjacent vines resulting in the lowering of leafhopper densities in such vines.
5 Results indicate that habitat diversification using summer cover crops that bloom most of the growing season, supports large numbers of predators and parasitoids thereby favouring enhanced biological control of leafhoppers and thrips in vineyards.
... Moreover, in the first experiment the higher presence of natural enemies, such as parasitic wasps and assassin bugs, on non-mowed inter-row vegetation was related to the presence of standing vegetation, which provides food sources (such as pollen and nectar), refuge zone and alternative prey (e.g., aphids, data not shown) [2,16,25]. A higher presence of spiders was also recorded on vine canopy close to non-mowed inter-rows; standing vegetation also favored the presence of spiders by providing habitat and food sources (insects and mites on the vegetation are potential prey), as observed in Californian vineyards [26,27]. In fact, weeds are important components of the vineyard agro-ecosystems, since they support alternative prey/hosts, pollen or nectar as well as microhabitats that are unavailable in weeded monocultures [2,25]. ...
... Regarding the parasitism rate of leafhoppers eggs, no differences were recorded confirming trends observed by Nicholls et al. [26] in their studies on cover crops. They argued that mowing of cover crops forced egg parasitoids to move to adjacent plots, so no differences were observed between treatments. ...
... They were more abundant on both late and standard mowed green manure strips as compared to the control plots and, for spiders, also on vine canopy adjacent to plots where green manure was mowed later. The presence of the standing vegetation provides habitat and food sources for natural enemies, as observed in the previous trial on the groundcover management and in other studies [26,27]. Cover plants like alyssum, buckwheat and "vetch-oat" showed attractiveness to some Hymenopteran parasitoid taxa in vineyards [35], but the response of a particular family depended on the plant species. ...
In this study, the effects of habitat management practices on both pests and beneficial arthropods were evaluated in vineyards of North-eastern Italy through different field experiments: (1) mowing of inter-row spontaneous grasses in conventional and organic vineyards, (2) different timing of mowing of a green manure mixture, and (3) comparing different green manure mixtures. The first experiment followed a split-plot design, while randomized block design was used in the second and third experiment. In each experiment arthropods were sampled using different methods: leaf sampling, beating and sweep net sampling. Non-mowed spontaneous grasses in inter-rows of vineyards favored the abundance of natural enemies (e.g., predatory mites, parasitic wasps and spiders), and sometimes grapevine leafhoppers. Many arthropod species were recorded in higher numbers in organic vineyards. Late mowing of green manure favored beneficial arthropods (e.g., spiders and parasitic wasps), while it did not influence herbivore density. Groundcover management practices, aimed at increasing plant biodiversity in vineyards, could be a useful tool to enhance beneficial arthropod abundance, although the adoption of this practice should be carefully evaluated when pests occur. Semi-natural areas can contribute to create a more pest-stable agro-ecosystem and should be integrated with appropriate ecological infrastructures surrounding vineyards.
... One of the best studies of natural enemy groups is Hymenoptera, for which there are different examples of parasitoids which increase when cover crops are used. The presence of Anagrus, egg parasitoids of Cicadellidae, increased with cover cropping (Begum et al., 2006;Centinari et al., 2016;English-Loeb et al., 2003;Nicholls et al., 2008Nicholls et al., , 2000Smith et al., 2015) and Erythroneura (Cicadellidae) population, in turn, decreased. The only exception found to this behaviour is an experiment performed in California, where the presence of cover crops did not affect Anagrus (Wilson et al., 2017). ...
... Both parameters were greater when adults had access to flowering Fagopyrum esculentum rather than plants without flowers. Moreover, the longevity of Anagrus was increased when provided with honey or sugar water compared to water only.In field experiments, it was also observed that the rate of parasitism increased Nicholls et al., 2008) or remained unaltered (Nicholls et al., 2000) when cover crops were established. ...
... A positive response of predatory thrips (spiders, Nabis sp., Orius sp., Geocoris sp., Coccinellidae and Chrysperla sp.) to cover cropping has also been observed, while reduced densities of western flower thrips pest (Frankliniella occidentalis) have been reported in cover-cropped plots (Nicholls et al., 2000). ...
This work seeks to synthesise the knowledge on the use of cover crops in vineyards in the last 20 years, emphasising on the one hand, soil characteristics such as nutrition, organic carbon, structure or erosion and, on the other hand, environmental factors such as soil and biodiversity in vineyards, and gas emissions.
A systematic review was made using Scopus-index journals for the past 20 years (1999 - 2018). The selection was independently done by two researchers, selecting a total of 272 published papers related to cover crops in the vineyard. Each article was categorised according to its theme and metadata were created, considering all relevant information from an agro-ecological point of view.
The use of cover crops has a positive effect on the vineyard by increasing soil organic carbon (SOC), improving water infiltration and aggregate stability, and reducing erosion and greenhouse gases emission to the atmosphere. Furthermore, there is an increase in biodiversity, both in soil and the vineyard. Finally, cover crops do not constitute as a rule a major competition for nutrients to the vines except for nitrogen when grass covers are used. Contrarily, legume cover crops generally increase N in the soil, although its availability for plants is not immediate.
This review constitutes an objective tool to help growers when considering the use of cover crops in vineyards that, based in a systematic review, provides relevant information depending on the characteristics of the growing condition of the vineyard.
... Various field-and farm-scale habitat management practices that aim to improve farmland habitat conditions have been explored and implemented (Landis et al. 2000;Liere et al. 2017). Some common practices include the establishment of uncultivated field margins and hedgerows (Altieri 1999;Benton et al. 2003), 1 3 creation of beetle banks (i.e. raised strips of sown grass that act as refuge for beneficial insects), insectary plantings (Thomas et al. 2002;Tillman et al. 2012) and the use of cover crops (Nicholls et al. 2000;Danne et al. 2010) to provide additional resources for invertebrates. Cover crops, which are non-economic crops planted between or underneath crop rows, is a particularly important ecological management tool in perennial agroecosystems, such as viticulture (Tillman et al. 2012;Muscas et al. 2017). ...
... This can lead to enhanced ecosystem services. For example, cover crops have been shown to increase the number of arthropod natural enemies (Altieri 1999;English-Loeb et al. 2003), which can lead to reduced pest abundances (Nicholls et al. 2000). ...
... In addition, other studies have shown that higher habitat complexity through increased vegetation structural complexity (Frank and Shrewsbury 2004;Danne et al. 2010) may provide greater refuges and increase prey availability for predaceous arthropods such as beetles and spiders (Schmidt et al. 2005). Plant diversity is an important factor for shaping arthropod network structures (Welti et al. 2017), with increased vegetation structural complexity within a habitat also providing alternative or additional resources for other arthropods (Nicholls et al. 2000;English-Loeb et al. 2003;Hannah et al. 2013). ...
Cover crops can enhance biodiversity in perennial agroecosystems, with native cover crops potentially having additional biodiversity benefits. We assessed the effect of native cover crops on vineyard arthropods in the Cape Floristic Region using pitfall traps and vacuum sampling. Generalized linear mixed models and Permanova analyses were used to compared the abundance, species richness and assemblage structure of soil surface-active (free living arthropods found on the soil surface) and plant-dwelling arthropods (arthropods found predominately on the vegetation). We also used model selection and BIO-ENV to determine environmental drivers of arthropod diversity among three treatments of vineyards with bare ground, exotic cover crops or native cover crops, and nearby fynbos remnants as reference sites. Vineyards with native cover crops had significantly higher overall plant-dwelling species richness (52.57 ± 3.03), compared to exotic cover crop (28.64 ± 2.66), bare ground vineyards (18.57 ± 2.98) and even the fynbos sites (21.29 ± 1.78). A similar trend was found for overall plant-dwelling arthropod abundance. In contrast, surface-active arthropod richness was not influenced by treatment, whereas surface-active abundance was higher in less densely vegetated sites. Generally, plant-dwelling arthropods responded strongly to vegetation-related variables, whereas surface-active arthropods were responsive to soil-related parameters. Assemblages in vineyards with native cover crops did not resemble those in the natural reference sites as expected, likely due to disturbance factors, and plant compositional and structural differences. However, both surface-active and plant-dwelling assemblages had a high proportion of unique species in the native cover crop than found in the other treatments. Our results show that native cover crops enhance foliar arthropod diversity over and above exotic cover crops and contributes to farm-scale compositional heterogeneity. It therefore has potential to reduce arthropod diversity loss within farmlands and to contribute to more resilient vineyard agroecosystems.
... In our result, we have found that the abundance of E. onukii was significantly greater in the intercropped tea plantations, which is consistent with the studies of Ye et al. (2010) and Jiang et al. (2014). Conversely, however, Nicholls et al. (2000), Chen (2002), Song et al. (2006), and Zhang et al. (2014) have found that appropriate cover crops significantly decreased the abundance of leafhoppers Erythroneura elegantula Osborn (Hemiptera: Cicadellidae) or Empoasca vitis Göthe (Hemiptera: Cicadellidae) in vineyard or tea plantations, respectively. Nevertheless, Greg et al. (2003) found that the abundance of leafhoppers Erythroneura spp. ...
... This study is in line with Song et al. (2006), who reported that when cover crops were present, the abundance of a tea geometrid moth (E. griseescens) has decreased in tea plantations, similar to Nicholls et al. (2000) who found deplated thrips abundances in intercropped organic vineyard. ...
... In our study, all ground cover treatments demonstrated an increase in the abundance of beneficial arthropods, which, to some extent, may explain the lower abundance of Thysanoptera or Geometridae caterpillars detected in the intercropped tea plantations. This is consistent with previous research (Nicholls et al. 2000, Chen 2002, Song et al. 2006, Li et al. 2016a, which found that pests reduction may be attributed, in part, to enhanced abundance of certain groups of spiders or parasitoids in the presence of cover crops, compared with monoculture systems. The simultaneously increased abundance of natural enemies and pest E. onukii in intercropped treatments is difficult to explain though. ...
Tea is an economically important crop, consumed by billions of people. Despite the increasing market for pesticide-free products, the use of pesticide in tea is still high. In order to investigate whether intercropping promotes biological control organisms, Chamaecrista rotundifolia (Pers.) Greene, Indigofera hendecaphylla Jacq., Trifolium repens L., and Vigna sinensis (L.) were separately intercropped with free weeding as control in a tea plantation at Yangli, China. Arthropods were collected by taking sweep-net samples, and treatment effects on assemblages were investigated. The combined species richness of all arthropods and that of parasitoids was significantly increased in intercropped treatments while the species richness of herbivores and predators was only greater in C. rotundifolia and I. hendecaphylla intercropped treatments. Compared with control, the combined abundance of all arthropods, and that of herbivores was lower, while the abundance of parasitoids and its taxa was greater in all intercropped treatments. The abundance of predators and its taxa was greater only in tea plantations intercropped with C. rotundifolia or I. hendecaphylla. Of the herbivores, the abundance of Empoasca onukii Matsuda, Sternorrhyncha, Aleyrodidae, and Pentatomidae was greater in the areas intercropped with C. rotundifolia in comparison with the control, but the abundance of Thysanoptera and Geometridae caterpillars was lower. The recorded increase in the abundance of beneficial arthropods may explain the lower abundance of Thysanoptera or Geometridae caterpillars detected in the intercropped tea plantations. Our results indicate that intercropping has the potential to enhance arthropod biodiversity, and to provide an option for sustainable pest control in tea plantations.
... Many vineyard growers use ground covers, either in the form of sown cover crops or resident floor vegetation, but effects on pest densities have not been consistent and/or economically significant (Daane, Vincent, Isaacs, & Ioriatti, 2018). Increases in natural enemy densities on grape vines have been recorded in the presence of cover crops, with either positive (Nicholls, Parrella, & Altieri, 2000) or neutral (Wilson, Miles, Daane, & Altieri, 2017) effects on suppression of leafhopper pests. On the other hand, Costello and Daane (2003) reported ground vegetation reduced leafhopper numbers but had no effect on spider numbers, and suggested that competition from weedy grasses influenced leafhoppers in a bottom-up manner by reducing vine vigour. ...
... variabilis (<25%), the dominant leafhopper species in our trials, and below the threshold of 32-36% parasitism that may be necessary for successful biological control (Hawkins & Cornell, 1994 no influence on leafhopper densities or egg parasitism rates (Wilson et al., 2017). Similarly, Nicholls et al. (2000) reported Anagrus did not Fiedler & Landis, 2007). Moreover, while some adult parasitoids are dependent on nectar and/or pollen for food (Heimpel & Jervis, 2005), plant species can vary widely in their ability to provide these resources (Wäckers, 2004). ...
... Numbers of spiders also increased slightly-but significantly-on vines in the non-irrigated native grass treatment. Studies using exotic plant species as ground covers also reported increases in generalist predator numbers (Nicholls et al., 2000;Wilson et al., 2017). ...
Mechanisms responsible for the success or failure of agricultural diversification are often unknown. Most studies of arthropod pest management focus on enhancing natural enemy effectiveness. However, non‐crop plants can also change crop host quality by reducing or adding soil nutrients or water, and therefore improve or hamper pest suppression. Native perennial ground covers may provide food or habitat to natural enemies and, in terms of competition for soil nutrients or water, be more compatible with crop management than exotic annuals.
We conducted a 3‐year vineyard study to examine the impacts of native perennial grasses on pests, natural enemies, crop plant condition and soil properties. We included three ground cover treatments: bare soil with a grower standard drip irrigation; native grasses with drip irrigation; and native grasses with drip irrigation as well as an additional flood irrigation to keep the grasses green and growing during the season.
Numbers of leafhopper pests Erythroneura spp. decreased in both native grass treatments, where parasitism rates were higher. Vine petiole nitrate levels were lower in grass treatments, indicating competition for soil nitrogen, which is most often considered to be detrimental. Berry weight was higher in the irrigated treatment but did not differ between the bare soil and non‐irrigated grass treatment. Grape °Brix was similar in the bare soil and native grass treatments, suggesting native grasses did not compromise grape quality. In fact, leaf water stress was lower and soil moisture higher not only in the irrigated grass treatment but, at times, in the non‐irrigated grass treatment, compared with the bare soil treatment.
Synthesis and applications . Our work shows that native grasses contribute to a reduction in vineyard leafhopper pests by reducing host quality through competition for soil nitrogen and providing food resources and/or habitat for natural enemies. Native grasses also improve soil water content and may be part of a water conservation program for perennial crops in dry climate regions.
... The importance of herbaceous vegetation in vineyards (both native grasses and cover crops) to obtain an increased number of natural enemies and greater control of pest populations, such as spider mites, thrips and leafhoppers are well known (Altieri and Schmidt, 1985;Settle et al., 1986;Nicholls et al., 2000;Hanna et al., 2003;Costello andDaane, 1998, 1999;Daane and Costello, 1998;Begum et al., 2006). In particular, the interrow ground cover can enhance pest suppression by increasing survival, reproduction and density of beneficials since in this habitat they can find alternative preys or hosts and also alternative foods because many of them are omnivorous species, either at a specific stage of development or for a lifetime. ...
... Therefore, it seems that these mymarid parasitoids were not favoured by the availability of herbaceous flowering plants. Similar results were obtained in other studies on Anagrus epos Girault, a parasitoid of North American leafhoppers in vineyards (Nicholls et al., 2000). ...
... A lower leafhopper infestation in the mowing treatment might be related to reduced vine vigour as well as to the higher abundance of spiders on canopy, as already reported for American leafhoppers (Nicholls et al., 2000;Altieri et al., 2005;Wilson et al., 2015). In particular, in Californian vineyards a higher spider density, favoured by ground cover, reduced Erythroneura spp. ...
... Various habitat diversification schemes have been suggested to address this, including the use of annual cover crops (Ingels 1998, Dufour 2000. Studies evaluating the use of cover crops to enhance biological control of Erythroneura leafhoppers in vineyards have found either no change (Altieri andSchmidt 1985, English-Loeb et al. 2003) or decreased leafhopper densities in plots with a cover crop (Settle et al. 1986, Wolpert et al. 1993, Roltsch et al. 1998, Nicholls et al. 2000, Costello and Daane 2003, Hanna et al. 2003. While some have concluded that the effect of cover crops on leafhoppers is mediated by increased natural enemy populations (Roltsch et al. 1998, Nicholls et al. 2001, Hanna et al. 2003, others suggest an additional or primary contribution to changes in vine vigor (Costello and Daane 2003). ...
... A number of studies have evaluated the use of cover crops to increase biological control in vineyards (Berndt et al. 2002, Danne et al. 2010, Simpson et al. 2011, Irvin et al. 2014) and of Erythroneura leafhoppers in particular (Wolpert et al. 1993, Costello and Daane 2003, Hanna et al. 2003, although only a few have utilized flowering summer cover crops (Nicholls et al. 2000, English-Loeb et al. 2003. More recently, studies have begun to investigate the influence of landscape diversity on vineyard arthropods (Botero-Garc es and Isaacs 2004, Thomson et al. 2010, Hogg and Daane 2011, 2013, D'Alberto et al. 2012) and biological control of pests Hoffmann 2009, 2013) and specifically leafhoppers (Wilson et al. 2015a). ...
... The higher abundance and evenness of natural enemies on the ground covers in plots with flowering cover crops seen in this study are likely the result of increased availability of floral nectar, pollen, shelter, and/or alternate prey (Landis et al. 2000). Increased natural enemy populations on the flowering cover crops follow similar observations from previous vineyard cover crop trials (Altieri and Schmidt 1985, Nicholls et al. 2000. However, natural enemy response to the flowering cover crops was much weaker in the vine canopy itself. ...
The influence of local and landscape habitat diversification on biological control of the Western grape leafhopper (Erythroneura elegantula Osborn) by its key parasitoids Anagrus erythroneurae S. Trjapitzin & Chiappini and Anagrus daanei Triapitsyn was studied in wine grape vineyards. At the landscape scale, Anagrus rely on alternative host species in non-crop habitats outside of the vineyard to successfully overwinter, while at the local scale vineyard diversification can provide resources, such as shelter and floral nectar, which improve parasitoid performance. In a two-year experiment, plots with and without flowering cover crops were compared in vineyards representing a gradient of landscape diversity. While the cover crops did attract natural enemies, their populations were unchanged in the crop canopy and there was no difference in parasitism rate, leafhopper density, crop quality, or yield. Vineyards in diverse landscapes had higher early-season abundance of Anagrus spp., which was linked to increased parasitism and decreased late-season populations of E. elegantula. Leafhopper densities were also positively associated with crop vigor, regardless of landscape or cover crops. Flowering cover crops did increase abundance of some natural enemy species as well as parasitism rate in vineyard landscapes with intermediate levels of diversity, indicating a local × landscape interaction, although this did not lead to reductions in E. elegantula densities. These findings indicate that, in this agroecosystem, landscape diversity mediates and in many ways outweighs the influence of local diversification and that E. elegantula densities were regulated by a combination of biological control and crop vigor.
... In general, the abundance of natural enemies is higher in more diverse ecosystems because vegetation cover provides both additional habitat and food (Nicholls et al., 2000). However, there have been few attempts to document how vegetation cover enhances predation. ...
... A positive correlation between non-crop vegetation cover and predator densities and a corresponding negative correlation with pest insect densities have been demonstrated in other studies (Nicholls et al., 2000;Vogelweith and Thiéry, 2017). In our case, the responses of predation and of ant abundance in traps to inter-row management were correlated. ...
Biodiversity-friendly farming practices are taking centre stage, with herbicide use sparking major public debate on human health. Vegetation cover is increasingly used to enhance agroecosystem biodiversity and functions, providing important ecosystem services like biological pest control. However, further information is required on the relationship between vegetation cover, natural enemies, and pest predation. Using a sentinel prey experiment set up in 26 Mediterranean organic vineyards, we analysed the response of generalist predators, and the associated final predation and dynamics under three inter-row management types: bare soil, one out of two inter-rows vegetated and all inter-rows vegetated. Predation on sentinel prey was monitored on the ground and on the vine trunk throughout the daytime and after a night of exposure. Generalist predator abundance was quantified using pitfall traps. Final sentinel prey predation both on vine trunks and on the ground were significantly higher in fully vegetated vineyards, with a shorter prey survival time than in tilled vineyards. Both diurnal and nocturnal predation were significantly related to increased vegetation cover and richness. Moreover, 96 % of the identified predation events involved ants. We demonstrated the key role of vegetation cover in improving the predation function through a spill-over from the inter-row to the grapevine. Contrary to what is commonly observed in agrosystems, we clearly identified ants as the predominant predator both on the ground and on the vine trunk. Our study has important implications for Mediterranean vineyard management, promoting vegetation as a nature-based solution. Sustainable management of vineyard vegetation favouring the natural predator community may contribute to a reduction in pesticide use and fossil fuel consumption.
... Offspring sex ratios can be influenced by nectar availability, with some research finding a higher number of female offspring (Berndt & Wratten, 2005), while others reporting a more male bias, perhaps due to the longer lifespan of females (Markó et al., 2012;Witting-Bissinger et al., 2008). This may affect the primary goal of increasing parasitism of crop pests (Rusch et al., 2017); in some studies parasitoids showed an increase in parasitism rates (Balmer et al., 2014;Díaz et al., 2012;Zhu et al., 2017;Winkler et al., 2006), but other researchers found no difference in parasitism rates between control and floral resource plots (Berndt et al., 2002;Lee et al., 2006;Nicholls et al., 2000;Rebek et al., 2006). ...
... Two additional hemipteran Families collected in 2018, Geocoridae and Nabidae, are considered general predators and feed on a wide range of insects. These species are not commonly used in biological control programs but are often reported in surveys of natural enemies using floral resources (Balzan et al., 2014;Gontijo et al., 2013;Nicholls et al., 2000). There is limited research indicating their use of nectar or pollen resources (Lundgren, 2009), suggesting they were attracted to T. vulgaris as a source of prey. ...
Current agroecosystem management practices have a negative effect on natural enemies and their ability to control insect pests. Conservation biological control through the addition of flowering resources can manage food resources for natural enemies. These floral resources can also provide multiple ecosystem services. Study goals were to determine if perennial Thymus vulgaris L. was attractive to natural enemies and if so, could it be a dual use resource encouraging pest management and providing harvestable product. In 2018 plots in three locations were used to examine the effect of habitat throughout the growing season on the attractiveness of T. vulgaris. Large numbers of Thysanoptera and Hemiptera were collected in all locations, represented by phytophagous Aphididae and Thripidae, and predatory Anthocoridae. Location influenced other families to varying degrees. Seasonal specimen counts were influenced by vegetation density, floral phenology, and predator/prey relationships. In 2019 replicated plots of three treatments were used to examine if harvesting plant material affected the attractiveness of T. vulgaris to natural enemies. Total specimens in 2019 were not significantly different among treatments, indicating removal of blooms did not significantly affect the attractiveness of T. vulgaris. Significant numbers of Thysanoptera and Hemiptera were again collected in all treatments, represented by phytophagous Aphididae and Thripidae. Greater numbers of Diptera and Hymenoptera were also collected. Significant numbers of Thripidae, Aphididae, Mymaridae, and Platygastridae were found in the Family level analyses. Results from both years indicate T. vulgaris was attractive to natural enemy and phytophagous Families. Data from 2018 suggest natural enemy families were attracted to alternative prey and hosts utilizing the foliage rather than flowers but the use of nectar and pollen cannot be ruled out. Data from 2019 suggest the presence of flowers played an important role in the attractiveness of T. vulgaris to micro-hymenopteran parasitoids, Syrphidae, and native Apidae. In conclusion, Thymus vulgaris has the potential to be a dual use floral resource that benefits growers through supporting native enemy populations and pollination services, as well as provide income from the harvest of foliage. It could also be used as a beneficial, harvestable floral resource in urban gardens to encourage pollinator conservation and natural pest control.
... 1,2 Consequently, the quality of tea products can be severely affected by leaf damage caused by the TGL, 2 resulting in a total annual economic loss of up to 15-50% of the Chinese tea economy. 2 In tea plantation areas, E. onukii has many overlapping generations (up to [10][11][12][13][14][15][16][17] in 1 year. The TGL remains active throughout the year but maximum population growth occurs from May to July and from September to November in tea plantations. ...
... However, Jiang et al. 16 found the opposite results when compared to conventional clearing tillage in a tea plantation (Table 1). Costello and Daane 13 and Nicholls et al. 17 found that the abundance of grape leafhoppers (Erythroneura spp.) was lower in intercropping treatments than in monocultures in vineyard systems (Table 1). However, English-Loeb et al. 18 did not find significant effects in intercropped grape ecosystems (Table 1). ...
BACKGROUND
Empoasca onukii, the tea green leafhopper, is a key pest of tea whose control often requires the extensive use of insecticides. As a predator of the tea green leafhopper, the mite Anystis baccarum is a potential biological control agent worldwide, though little is known about how intercropping cover crops can impact its suppressing effect on E. onukii. Therefore, we conducted a field experiment to investigate how the relationship of the abundance of the predatory mite and its leafhopper prey is influenced by two different cover crops and a manually weeded inter‐row treatment as a contrast to naturally growing vegetation in a tea plantation in China.
RESULTS
The abundance of A. baccarum was significantly higher in tea canopies of intercropped treatments than in canopies over natural ground cover. Litter samples showed higher abundances of A. baccarum when tea was intercropped with Paspalum notatum than with natural ground cover in the first year of treatment. The abundance of E. onukii in tea canopies was higher over the bare ground treatment in the first year but the opposite was observed in the second year.
CONCLUSIONS
Results suggest that the abundance of A. baccarum in a tea plantation is influenced by intercropping and it can affect its leafhopper prey, albeit with varying levels of suppression. For informing biological control and suppression of pests, long‐term experiments are needed to investigate the interactions of both pest and predator with cover crop treatments. © 2019 Society of Chemical Industry
... Mowing also forces beneficial arthropods to migrate to adjacent crops. An example is Anagrus epos (Hymenoptera: Mymaridae, main parasitoids of leafhoppers), which migrate to vineyards when the flower strip is mowed (Nicholls et al., 2000). However, pests living on the flowers will also migrate to the crop. ...
... However, pests living on the flowers will also migrate to the crop. Therefore, it is important to understand the biology of the pests and the phenology of the crop and species in the flower strip to best choose when to mow (Nicholls et al., 2000). In general, infrequent mowing in the spring or autumn, avoiding mowing in the summer, and leaving the hay on the field is considered optimal (Pfiffner and Wyss, 2004). ...
Organic Farming
Global Perspectives and Methods
2019, Pages 1-16
Chapter 1 - Contribution of Organic Farming Towards Global Food Security: An Overview
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Terence EpuleEpule
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https://doi.org/10.1016/B978-0-12-813272-2.00001-X
Abstract
This chapter verifies the contributions of organic and inorganic farming within the context of global food security. This chapter is based on data obtained from a synthesis of existing literature obtained through Google Scholar, the Scientific Citation Index (SCI) database, and ISI Science. The first part of this work explores the conceptual issues around organic and inorganic farming; this is followed by a synthesis of the potential effects of organic and inorganic farming on global food security and finally the effects of organic and inorganic farming on food security in Africa. The results from this synthesis show that organic farming can indeed reduce global food insecurity but there is a limitation to the extent to which this can be obtained as it has been observed that there is a threshold beyond which a combination of organic and inorganic farming options produce the best effects and organic farming alone cannot sustain production. A system dependent on organic farming is rather complex and may warrant that: the current scale of arable production be expanded while the farmers need to be trained on how to valorize the advantages of organic farming especially in Africa. Understanding how to make use of other components of agro-ecology is mandated. The weaknesses of conventional farming must be evaluated in detail by setting up pilot agro-ecology farms and comparing their yields with conventional farms around the world in general and in Africa in particular. Most of the studies consulted recommend either inorganic farming or a combination of inorganic and organic. Therefore, as a way forward, farmers must be given the opportunity to take decisions on which way to go and this should be based on the availability of sufficient information on the economic, social, and environmental sustainability implications of their actions. In addition, the markets for farm inputs should become more competitive and efficient, and this will trigger lower prices and better services to the farmers.
... Summer flowering cover crops have greater potential to support natural enemies and increase biological control [58][59][60][61], but are much more difficult to integrate into vineyards due to their water requirements, competition with the grape vine, and interference with workers and machinery moving through the vineyard. Regardless, a small number of growers still experiment with various flowering summer cover crops (Figure 1), which include buckwheat (Fagopyrum esculentum), sweet alyssum (Lobularia maritima), purple tansy (Phacelia tanacetifolia), and clovers (Trifolium spp.). ...
... While the use of summer flowering cover crops is still relatively rare in California, primarily because of irrigation requirements, demand is sufficient for many seed companies to offer various "insectary blends" of flowering cover crop seeds. The effect of summer flowering cover crops on biological control in vineyards is unclear, and studies have not produced consistent outcomes [58][59][60][61][62][63][64]. In some cases, changes in pest densities in the presence of flowering cover crops was related to changes in vine vigor induced by competition from the cover crop [53]. ...
Grape growers in California utilize a variety of biological, cultural, and chemical approaches for the management of insect and mite pests in vineyards. This combination of strategies falls within the integrated pest management (IPM) framework, which is considered to be the dominant pest management paradigm in vineyards. While the adoption of IPM has led to notable and significant reductions in the environmental impacts of grape production, some growers are becoming interested in the use of an explicitly non-pesticide approach to pest management that is broadly referred to as ecologically-based pest management (EBPM). Essentially a subset of IPM strategies, EBPM places strong emphasis on practices such as habitat management, natural enemy augmentation and conservation, and animal integration. Here, we summarize the range and known efficacy of EBPM practices utilized in California vineyards, followed by a discussion of research needs and future policy directions. EBPM should in no way be seen in opposition, or as an alternative to the IPM framework. Rather, the further development of more reliable EBPM practices could contribute to the robustness of IPM strategies available to grape growers.
... Therefore, pest and disease control require specific cultural practices that promote the development of natural enemies or reduce the optimal conditions for disease development. Among the beneficial fauna in vineyards, ladybugs (Coccinella septempunctata), lacewings (Chrysoperla carnea), wasps of the genus Trichogramma, anthocorid bugs of the genus Orius, hoverflies of the genus Syrphus and even microorganisms like Bacillus thuringiensis are amongst the most well known (Hommay et al., 2002;Nicholls et al., 2000;Ricarte et al., 2011;Ruiz de Escudero et al., 2007;Sattar et al., 2018;Sattar & Abro, 2011;Yu et al., 2014). When preventive cultural practices such as those previously mentioned are not sufficient, there are still some chemical treatments that are allowed in organic systems. ...
The grapevine is one of the most important perennial fruit crops worldwide. The historical stability of winegrowing methods has spanned almost 3000 years since the introduction of viticulture in Europe. However, in the last 70 years, the wine sector in the Europe has experienced substantial transformations. These changes are attributed to the widespread adoption of mechanisation and industralisation in the 1950s and the establishment of the Common Agricultural Policy (CAP). The growing concern for the environment and climate change in the European Union (EU) has significantly influenced the successive reforms of the CAP. These reforms have resulted in the acquisition of new commitments to protect the environment, mitigate climate change and reduce biodiversity loss over the years. In this work, we carried out a critical analysis of the most relevant aspects of the new CAP and address the regulatory framework of organic agriculture in the EU as a tool for improving the sustainability of vineyards. Currently, Spain is the country with the largest vineyard area in the world, reaching 964,000 hectares. This represents 13% of the world's vineyards and 30% in the EU, which demonstrates the importance of this crop in Europe. Due to its relevance, we focused our critical analyses of the new CAP on Spain as a case study. The latest reform of the CAP, applicable for the period 2023‐2027, is the most ambitious in environmental terms and includes instruments such as reinforced conditionality, eco‐schemes and payments for agri‐environment–climate commitments. Finally, we propose that by integrating concepts and management strategies from current organic and regenerative viticulture together with historical strategies derived from treatises and classic authors across a wide range of societies and cultures, the goals of the new CAP can be successfully met. This will contribute to reuniting the past, the present and the future of viticulture for a more nature‐based winemaking.
... Although some thrips, including onion thrips, were observed on the flowers of buckwheat, lacy phacelia, and coriander, their numbers could not be quantified. Buckwheat and lacy phacelia attract a few thrips species (Wnuk 1998;Nicholls et al. 2000) and act as decoy plants for onion thrips in onion fields (Trdan et al. 2006). If more adult syrphids are not attracted to the flowering plants for egg-laying than thrips, onion thrips may cause more damage to onions. ...
Onion thrips (Thrips tabaci) are a major pest of onion crops, but they can be controlled using syrphid larvae, which are omnivorous, as biological control agents. The introduction of secondary plants may enhance syrphid activity and contribute to the suppression of onion thrips population in onion–barley intercropped fields. Therefore, two experiments were conducted to evaluate the effect of introducing secondary plants on the population of onion thrips and the occurrence of syrphids in onion–barley intercropped fields. In the first 2-year experiment, buckwheat, lacy phacelia, and coriander planted around barley-intercropped onion fields did not result in a significant reduction in the number of onion thrips. However, in the second experiment, which employed mixed intercropping of barley and buckwheat, significantly greater suppression of onion thrips population was observed in the mixed intercropping plots than in plots containing only barley intercropping. In addition, the number of syrphid eggs on intercropped barley was significantly higher in the mixed intercropping plots than in plots containing barley alone, demonstrating that planting flowering plants near barley can attract hoverflies and increase oviposition on barley. Furthermore, three-year experiments revealed more syrphid larvae on onion plants than on barley, with eggs found only on barley. These findings indicate that hoverflies oviposit on intercropped barley; then, the hatched larvae move to onion plants to prey on onion thrips. Overall, this study offers great insights into the potential use of intercropping with flowering plants to boost natural biological control of onion thrips, providing implications for sustainable pest management in onion production.
... Indeed, the jumping spiders (Salticidae) and lynx spiders (Oxyopes spp.), recorded in high numbers in the present study, are reported as predators of H. vitis [39,75] and other Cicadellidae [76]. An association between the increase in spiders, as a consequence of cover crops in vineyard inter-rows, and leafhopper predation was reported for E. elegantula [77]. Under laboratory conditions, a high consumption of leafhoppers by lynx spider species (Oxyopes javanus Thorell) and Salticus sp. was recorded [78,79]. ...
Inter-row management in vineyards can influence the abundance of grapevine pests and their natural enemies. In 2013–2015, in a vineyard in northeastern Italy, the influence of two vineyard inter-row management strategies (i.e., alternate mowing, AM, and periodical tillage, PT) on the population dynamics of grapevine leafhoppers Hebata vitis and Zygina rhamni and their natural enemies, the mymarid Anagrus atomus and spiders (Araneae), and other hymenopteran parasitoids, were studied with different survey approaches. The infestations of both leafhoppers were lower in AM than PT due to the reduced leafhopper oviposition and higher nymph mortality in AM. This occurred although leafhopper egg parasitization by A. atomus was greater in PT than AM according to a density-dependent relationship with the leafhopper egg amount. Hymenopteran parasitoids other than A. atomus were the most abundant in AM, probably due to the higher availability of nectar and pollen than in PM. The significantly higher population densities of hunting spiders in AM than PT can be associated with the higher predation of leafhopper nymphs. Therefore, the study demonstrated that the alternate mowing of vineyard inter-rows enhances the abundance of natural enemies, such as spiders and hymenopteran parasitoids, and can contribute to grapevine leafhopper pest control.
... Cover crops also frequently result in an increased population of arthropods, small mammals and birds (Abad et al., 2021a), and may enhance the presence of species that act as natural enemies against vineyard pests (Begum et al., 2006;Burgio et al., 2016;Nicholls et al., 2000), thus contributing to decreasing pest pressure (Daane et al., 2018;Sanguankeo & León, 2011). Cover crops can also result in greater microbial biomass because of increased soil C and rhizodeposition (Steenwerth & Belina, 2008). ...
Grapevine is one of the most important perennial fruit crops worldwide. Historically, vineyards were compatible with soil conservation practices and multitrophic biodiversity, but vineyards are now generally eroded and biologically impoverished, making them more susceptible to pests and diseases. However, the idiosyncrasy of the wine sector places wine growers in a unique position to lead the adoption of a range of sustainable management strategies and, thus, to pioneer a wider transformation of the agricultural sector. In this article, we provide an overview of nature‐based management strategies that may be used for the regeneration of the functioning and biodiversity of vineyards and that may also lead to improved plant nutrition, grape berry quality and the suppression of pathogens and pests. These strategies include the use of microbial and nonmicrobial biostimulants, fertilization with organic amendments as well as foliar fertilization with nature‐based products, the use of cover crops and the reintegration of livestock in vineyards, especially sheep. We will also pay special attention to the implementation of circular economy in the vineyard in relation to the previously mentioned management strategies and will also discuss the importance of considering all these aspects from a holistic and integrative perspective, rather than taking them into account as single factors. Assuming the integral role of soils in the functioning of agroecosystems, soils will be considered transversally across all sections. Finally, we will argue that the time is now ripe for innovation from the public and private sectors to contribute to the sustainable management of vineyards while maintaining, or even improving, the profit margin for farmers and winemakers.
... Do not transcend understanding towards socioecological interactions. Altieri et al. 2012;Martínez et al. 2013;Altieri 1983;Ponti et al. 2007;Colvin and Gliessman 2012;Nicholls et al. 2000;Liere et al. 2012;Zapata et al. 2009;Soto et al. 2002;Posada et al. 2013;Patiño and Sánchez 2012;Hilimire et al. 2013. ...
p>Agroecology proposes a new epistemological and methodological paradigm to understand the reality of farming and livestock production systems that are in turn nature-society systems. The research questions around these have traditionally been resolved from two methodological approaches: quantitative and qualitative. Although each complements the other, there have not been sufficient approximations from a perspective that would integrate them. A holistic, transdisciplinary agroecological proposal should transcend the theoretical discourse and become practical trough research aiming to understand the socio-ecological relationships in the agroecosystems, report the complex phenomena arising from such relationships and prepared detailed diagnostics from a systemic point of view. Reflections are presented here on the traditional methodological approaches to agroecology and new proposals that respond to the epistemological approach of the agroecological discourse.
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... Another added benefit is that cover crops, depending on the plant species selected, can serve as habitats, refuges, alternative food sources, or attractants for BCAs. Thus, flowering cover crops, for instance, can enhance parasitism and predation of target pest species (Nicholls et al., 2000;Hanna et al., 2003;Sáenz-Romo et al., 2019). Lastly, among the main concerns of cover cropping in vineyards is the occurrence of fungal diseases, so, as in the case of mulching, a proper selection of plant varieties must be essential (Rombough, 2002;Pedneault and Provost, 2016). ...
Entomopathogenic nematodes (EPNs) are biological control agents that often occur naturally in crop soils. The conventional agricultural practices of regular tillage and agrochemical applications predispose to soil biodiversity losses, compromising soil health and disrupting the natural balance of abiotic and biotic factors that might modulate EPN abundance and activity. The vineyard, which supports a relevant socio-economic sector worldwide, is one of the most intensively managed cropping systems. Therefore, approaches rather than reliance on mechanization and agrochemicals are needed to achieve more sustainable viticulture. We hypothesized that alternative strategies to tillage for soil management and the release of agrochemicals for pests, diseases, and weed management, such as cover cropping, mulching, and organic farming, would favor the native EPN community in vineyard soils. Therefore, our objective was to evaluate the impact of differentiated viticulture practices on native EPNs and other targeted organisms associated with their soil food web and how their assemblage might signal soil health in vineyards.
We implemented traditional and innovative methodologies to isolate and identify mesofauna to achieve this aim. Firstly, we estimated different soil activities, including those associated with EPNs, by baiting the soil samples with Galleria mellonella larvae. Besides, we used species-specific primers/probe qPCR sets to screen and quantify the occurrence and abundance of 10 EPN species and 12 organisms linked to their soil food web: four free-living nematodes (FLNs), six nematophagous fungi (NF), and two ectoparasitic bacteria (EcPB). Lastly, a third soil subsample set was employed to estimate the soil properties. Following this procedure, we performed three independent studies to evaluate the impact of different management practices on the EPN community and associated soils organisms in The Appellation of Origin (DOCa) Rioja vineyards (Northern Spain): (i) diverse cover crops (seeded with Bromus catharticus, flower-driven, and spontaneous) compared to regular tillage in an experimental vineyard, (ii) cover cropping and organic viticulture compared to regular tillage and Integrated Pest Management (IPM) in a survey comprising 80 vineyards, and (iii) various organic mulches (based on grape pruning debris, straw, and spent mushroom compost) compared to regular tillage and herbicide applications in an organic and IPM experimental vineyards.
We found seven EPN species and all the other screened species except the NF Arthrobotrys musiformis and the EcPB Paenibacillus nematophilus. The only EPNs reported in the three studies were Heterorhabditis bacteriophora, Steinernema feltiae, and the new EPN species S. riojaense, identified and isolated during the progress of this Thesis. Overall, EPN abundance and activity were higher for cover cropping and mulching than conventional soil management practices in both studies performed in experimental vineyards. However, the results obtained in the DOCa Rioja survey did not support this trend. It is possible that differential effects of diverse alternative strategies to regular tillage also affected the soil properties and, therefore, the EPN soil food web differentially. Indeed, we found lower numbers of potential enemies of EPNs, particularly NF, for spontaneous cover cropping and mulching based on spent mushroom compost, the treatments for which higher EPN activity rates and abundance were recorded.
On the other hand, in agreement with our hypothesis, organic viticulture enhanced the activity of native EPNs and the abundance and activity of the predominant EPN species, S. feltiae, in the DOCa Rioja survey. In addition, we obtained similar results for the organic vineyard in the mulching study. Organic viticulture also supported a higher FLN abundance and richness of the overall nematode species screened since the EPN species Steinernema affine, S. carpocapsae, and S. kraussei, as well as the FLN species Oscheius onirici, only occurred in organic vineyards.
Our results showed that organic viticulture and specific soil management practices that restrict or avoid regular tillage might support native EPNs in the vineyard, contributing to the maintenance of the ecosystem service these soil organisms offer as biological control agents. Moreover, these studies have illustrated how evaluating the EPN soil food web can signal soil health and the suitability of some viticulture practices over others. Applying innovative molecular tools and statistical analyses will improve understanding of the factors that determine the occurrence and distribution of EPNs in crop soils.
... However, in April, dry matter and tissue N concentrations in the spontaneous vegetation were also higher in the treatments that received more N as a fertiliser. These plants, which appear after the first autumn rains and develop during the winter, can play important roles by controlling soil erosion [55,56], increasing soil organic matter [57,58] and developing ecosystem biodiversity [59,60]. They also act as an N catch crop [21,61], justifying the promotion of their presence in orchard soils [62]. ...
Due to the high value of the fruit, the European chestnut (Castanea sativa Mill.), usually grown in agroforestry systems, has been planted as a single species in orchards managed with increasingly intensive cropping practices, such as the regular use of fertilisers. This justifies research into establishing fertilisation programmes oriented towards ecological intensification. In this study, the results of fruit production, plant nutritional status and soil properties are reported from a field trial in which three NPK fertilisers (20:7:10, 13:11:21 and 7:14:14) and a control treatment were used. Chestnut yields did not vary significantly between treatments, although the mean values of the control showed a clear downward trend. N supplied by the fertilisers seems to have been the most important factor in the difference between the fertilised and control treatments, since leaf N concentrations were lower in the control and often below the lower limit of the sufficiency range. Soil inorganic N levels in the autumn, and tissue N concentrations of the herbaceous vegetation developing beneath the trees, indicated risks of N loss to the environment and highlighted the importance of this vegetation remaining during the winter. The chestnuts’ poor response to fertiliser applications was attributed to the buffering effect of the large perennial structure of the trees on the distribution of nutrients to the growing plant parts. In large trees, it seems appropriate to base the annual fertilisation plan on leaf nutrient concentration. Thus, farmers probably should avoid spending money on fertilizer applications as long as leaf nutrient concentrations do not approach the lower limits of sufficiency ranges.
... Cover crops with fast growing canopies can suppress weeds by competing for sunlight and nutrients or through allelopathy with certain cover crops like sunn hemp (Crotalaria juncea L.), wild oat (Avena fatua L.), and cereal rye (Secale cereal L.) [8][9][10]. Some cover crops can also reduce pest pressure [11]. These improvements to the soil from cover crops can also contribute to a higher yielding, better quality cash crop while at the same time protecting environmental quality [12]. ...
... However, it was shown that the crape myrtle aphid, Tinocallis kahawaluokalani (Kirkaldy), decreased its abundance with hotter canopy temperatures [8]. The effect of service plants in reducing aphid populations by promoting biological control by predators or parasitoids has been reported for several crops, in part by using the same service plant species as we have used [18,[32][33][34][35][36][37][38][39][40][41][42]. In urban landscapes, service plants have also been employed to enhance the biological control of different pests [12,13,43], but no previous studies reporting aphid reduction have been found. ...
Oleander is very frequently planted as an ornamental shrub in urban areas of the Mediterranean. Its most common pest is the aphid Aphis nerii, and heavy infestations produce aesthetic damage and disturbances to the citizens, and they are frequently sprayed with insecticides in order to reduce the population density. One alternative method is conservation biological control which is enhanced by the provisioning of alternative food, refuges, and reproduction sites. In this study, the usefulness of four flowering service plants (Lobularia maritima, Calendula officinalis, Coreopsis grandiflora, and Achillea millefolium) is evaluated for aphid infestation levels and aphid natural enemy abundances. Aphid levels were consistently lower in oleander plots surrounded by service plants. Natural enemy abundances tended to be higher in plots surrounded by service plants, but significant differences could not be found until the fourth year of the study, when more lacewings, total predators, and mummies were higher in plots surrounded by service plants. On these plots, hoverflies, ladybeetles, and lacewings were the most common predators. Paragus sp. and Hippodamia variegata were the prevalent hoverfly and ladybeetle species, respectively. The potential toxicity effect on the prevalence of natural enemy species is discussed. On service plants, significantly more hoverflies were recorded on L. maritima than on C. officinalis and C. grandiflora, and more true bugs were recorded on C. officinalis and A. millefolium than on L. maritima or C. grandiflora. Our results suggest that planting service plants (such as sweet alyssum, marigold, or yarrow) surrounding oleanders can improve conservation biological control by enhancing the abundance of aphid natural enemies and thus a reduction of the abundance of A. nerii.
... However, in contrast to the results for pollinator species richness (which was highest in the wild bee mix treatment), wasp richness was actually highest in the rows permitted to naturally regenerate. Similarly, previous studies report that introduced floral resources are beneficial for parasitoid wasps in vineyards (Judt et al., 2019;Nicholls et al., 2000), as is natural regeneration (Möller et al., 2020) and simply a reduced mowing regime (Zanettin et al., 2021). ...
Traditional vineyards are generally intensive monocultures with high pesticide usage. Viticulture is one of the fastest‐growing sectors of English agriculture, although there is currently limited research on habitat management practices.
In a vineyard in East Sussex, England, we tested five inter‐row ground cover treatments on their potential in supporting beneficial insects: two commercially available seed mixes (meadow mix and pollen and nectar mix), a wild bee seed mix (formulated based on pollinator foraging preferences), natural regeneration, and regularly mowed grass.
Over two years, from May to August, we conducted monthly floral surveys and insect surveys using transect walks and pan traps.
The abundance and richness of flowers in the natural regeneration treatment were twice that of the regularly mown inter‐row treatment. By year 2, the abundance of “total insects” sampled was significantly higher in the wild bee mix compared to mown. Likewise, there was a significant effect of treatment type on pollinator richness, with a higher mean richness found in wild bee mix. Solitary wasp family richness was highest in the natural regeneration treatment and lowest in the mown treatment.
Given the rapid growth and lack of specific environmental recommendations for British viticulture, we demonstrate a simple and effective approach for supporting beneficial insects and ecosystem services. Promotion of perennial wildflowers through sowing or allowing natural regeneration in inter‐row ground cover in vineyards has the potential to boost biodiversity in vineyards on a large scale if widely adopted.
... The vineyard should be considered as a consociation, formed by the vines and the underlying grasses, both complementing the functions and ecosystem services of the vineyard. Associated plant diversity in vineyards may contribute to multiple ESs, such as mitigating soil erosion and, preserving soil fertility, biocontrol of vine pests by promoting colonization of vine rows by their natural predators (see in the following paragraphs and Nicholls et al., 2000), aesthetic value of viticultural landscape (Hervé et al., 2020), and conservation of endemic species (Gillespie and Wratten, 2012). Studying the benefits and ecosystem services supported by spontaneous flora in vineyard agroecosystems is a quite novel topic (Garcia et al., 2018), but findings suggest that vegetation cover should be used wherever soil and climate conditions are favorable. ...
Healthy soils form the basis of sustainable viticulture, where soil characteristics have a direct impact on wine quantity and quality. Soil not only provides water and nutrients to vines, but is also a living medium containing micro- and macroorganisms that perform many ecological functions and provide ecosystem services. These organisms are involved in many processes, from decomposing organic matter to providing minerals to vine roots. They also control diseases, pests, and weeds, in addition to improving the soil structure in terms of its capacity to retain water and nutrients. Related to decomposition processes, the carbon content of vineyard soils influences fertility, erosion and biogeochemical cycles, with significant implications for the global climate. However, common agricultural practices represent strong threats to biodiversity and associated ecosystem services provided by vineyard soils. As consumers increasingly consider environmental aspects in their purchase decisions, winegrowers have to adapt their vineyard management strategies, raising the demand for sustainable pest- and weed-control methods. This article presents a comprehensive review of the impacts of vineyard practices on the soil ecosystem, biodiversity, and biodiversity-based ecosystem services, and provides future prospects for sustainable viticulture.
... In integrated pest management, permanent cover crops in vineyards are preferable to tillage, as they contribute to reduce diseases (i.e. downy mildew, powdery mildew and bunch rots) and pests levels (Carsoulle 1995, Nicholls et al. 2000, Costello and Daane 2003, Hanna et al. 2003, Morlat and Jacquet 2003, Valdés et al. 2005, Serra et al. 2006, Valdés-Gómez et al. 2011. Plant protection can take advantage of cover-cropped inter-rows, such as lower damage by diseases and pests, lower spray-ing, and the possibility of postponing harvest due to lower incidence of bunch rots. ...
The vineyard inter-row management affects grapevine vegetative and bunch health status, as well as yield and grape quality parameters. Several studies assessed that cover-cropped inter-row in place of soil tillage often reduced plant vigour and yield but positively contributed to vineyard ecosystem services and, to a lower extent, to grape quality. In 2013 and 2014, two inter-row management strategies, i.e. soil tillage and mowing of spontaneous cover crops, were compared in an organic vineyard in northeastern Italy and cultivated with 'Sau-vignon Blanc' (Vitis vinifera L.), clones R3 and 297. In particular, the effects of tillage and mowing treatments on grapevine vegetative and bunch health status, yield and grape quality were evaluated. The vegetative parameters were lower in the mowing treatment than in the tillage one and in clone R3 compared to 297. The incidence of Botrytis cinerea was higher in the tillage treatment than in the mowing one and in clone 297 compared to R3. A significant reduction of the yield and bunch weight was ascertained in the mowing treatment, and these parameters were higher for clone 297 compared to clone R3. Titratable acidity was significantly higher in the tillage treatment than in the mowing one and in clone 297 compared to R3. Moreover, hue of berry skin was qualitatively better in the tillage treatment than in the mowing one. In the pedo-climatic conditions of Friuli Venezia Giulia (north-eastern Italy), the management of the vineyard inter-row with spontaneous cover crops proved to be effective to manage grapevine vigour, reducing yield and improving quality of the grapes during maturation. K e y w o r d s : 'Sauvignon Blanc'; clones; soil tillage; permanent green cover; Botrytis cinerea; hue of berry skin.
... In early studies, buckwheat and coriander were already successfully introduced into orchards , resulting for instance in higher adult fitness of the braconid wasp D. tasmanica (Stephens et al., 1998;Irvin et al., 1999;Irvin et al., 2006). Other field trials with buckwheat revealed reduced pest densities not only in apple orchards (Stephens et al., 1998;Irvin et al., 2000;Irvin et al., 2006) and vineyards (Nicholls et al., 2000;Berndt et al., 2002), but also in various field crops, such as cabbages (Luna et al., 2000;Pfiffner et al., 2009;Géneau et al., 2012), strawberries (Sigsgaard et al., 2013, and cotton inter-planted with buckwheat. (Li et al., 2019). ...
The codling moth Cydia pomonella (Linnaeus, 1758) (Lepidoptera: Tortricidae) is the major pome fruit pest worldwide, causing direct fruit damage and significant yield losses. The egg-larval koinobiont parasitoid Ascogaster quadridentata (Wesmael, 1835) (Hymenoptera: Braconidae) contributes to the natural regulation of codling moth populations. Similar to many other parasitoid Hymenoptera, adult A. quadridentata could also benefit from high plant diversity in orchards if it fed on flowers. However, its particular nutritional requirements are rather unknown. For the first time, possible effects of sugar or flower resources on the performance of this parasitoid were studied in laboratory experiments. Wasps fed with highly concentrated sucrose or glucose solutions lived three to five times longer than starving individuals. Trehalose also supported survival, whereas mannose was not suitable. Parasitoids were able to exploit sugar solutions of low (10%) to high (64%) concentrations. Survival was more than twice as long when flowers of buckwheat, coriander, wild carrot, and parsnip were offered. Parasitism capacity was strongly linked to female longevity and thus to adequate nutrition of adults. Under the prevailing experimental conditions, performance of wasps was three times higher on flower diet compared to that of starved wasps. Suitable plants flowering during the activity period of A. quadridentata might therefore improve the ecosystem service provided by this important codling moth parasitoid and help increasing functional biodiversity in orchards.
... Feeding on floral and extrafloral nectar can increase the longevity, fecundity, searching activity, parasitism/ predation rates, and female offspring sex ratios of natural enemies (Berndt and Wratten, 2005;Kost and Heil, 2005;Irvin et al., 2006;Hogg et al., 2011). Incorporating nectar producing non-crop resources (i.e., insectary plants) in agroecosystems may promote a greater diversity and abundance of natural enemies which can result in increased parasitism and predation, lower densities of pestiferous insects, and a concomitant reduction in economic damage to crops (Altieri and Schmidt, 1985;Liang and Huang, 1994;Nicholls et al., 2000;English-Loeb et al., 2003;Silva et al., 2010;Aguilar-Fenollosa et al., 2011). ...
Tamarixia radiata parasitizes nymphs of Diaphorina citri, a global citrus pest that vectors a bacterium that causes a lethal citrus disease, huanglongbing. The effects of four species of potted flowering native California plants, potted flowering buckwheat (Fagopyrum esculentum) and Euphorbia marginata (both non-native), honeydew from D. citri and Coccus hesperidum, cut flowers from lemon and orange trees, 50% honey-water, and water only on the longevity, survivorship and reproduction of T. radiata was investigated in the laboratory. Fecundity was measured by counting egg load of parasitoid cohorts ∼15 h of age at time of set up and those that were removed for dissection from test arenas at 1, 6, and 18 days after introduction, or at time of death. Maximum survival of female T. radiata was 34 days on honey-water. Survival on honey-water, buckwheat and C. hesperidum honeydew was statistically equivalent, and these three food treatments significantly enhanced parasitoid survival when compared with all remaining food treatments. Female T. radiata fed on D. citri honeydew survived an average of 5 days, which was 3 days longer, on average, than those provided with water only. Parasitoid egg load significantly decreased with increasing days alive, thereby demonstrating the synovigenic nature of T. radiata. Parasitoids that fed on buckwheat flowers and died from natural causes had, on average, 5 more mature eggs in their ovaries at time of death when compared to parasitoids that died when provided access to other experimental sugar sources that were tested. These results suggest that buckwheat may be a useful insectary plant in citrus orchards that could enhance the efficacy of T. radiata against D. citri.
... 5, 9.3.2 ;English-Loeb et al., 2003 ;Nicholls et al., 2000). ...
... The food chain supported on cover crops may favor pests or diseases, but it is usually expected that it can enhance auxiliary organisms. Relevant literature has demonstrated the role of local flora or sown species in the food or refugee of natural enemies of key pest of important crops (Nicholls et al., 2000;Berndt and Wratten, 2005;Irvin et al., 2016;Muscas et al., 2017). ...
... COCCINELLIDS DETERMINATION We separated coccinellids from the other specimens and stored them under alchool solution (70% volume). Classification at the species level was carried out, basing on morphological features and, if needed, by the genitalia analysis, according to the descriptions of PORTA (1929), FÜRSCH et al., (1967, GOURREAU (1974), CANEPARI (1983 and2000), CANEPARI & TEDESCHI (1977) and CANEPARI et al. (1985). Information regarding the food preferences of coccinellids were given by SAHAROUI (1994), IPERTI (1999), GERSON et al. (1975) The community structure of coccinellids of the three vineyards was analyzed on the base of their species compositional biodiversity and also by grouping them on the base of the trophic guild they belong (Saharoui,1994 modified). ...
... Vegetation cover, biomass and plant diversity are important drivers of below-ground ecosystem processes by influencing the faunal, microbial biomass and soil organic matter dynamics (Buchholz et al., 2017). Vegetation in vineyards also provides food and structure for many arthropod taxa (Altieri et al., 2005) which influences pest control by providing habitats for natural enemies of vine pests (Nicholls et al., 2000;Danne et al., 2010). ...
... In the case of parasitoids, the positive synergistic effect between surrounding vineyard area and vegetation cover within the sampled vineyards might also be due to the host-and habitat-specification of parasitoids [64,83] and thus to their stronger response to landscape complexity at smaller scales [28]. Our results on parasitoids underline previous findings that vegetation cover could be beneficial for natural enemies [38,[84][85][86] by providing resources such as nectar, pollen, alternative hosts and shelter [40,70,87,88]. ...
Land use at landscape and field scales can increase the diversity and abundance of natural enemies for pest control. In this study, we investigated interactions between landscape elements (semi-natural vegetation, olive orchards, vineyards, other agricultural areas) and inter-row management (vegetation cover vs. bare soil) in relation to arthropod populations in Andalusian vineyards. Arthropods were collected from grapevine foliage in 15 vineyards using suction sampling. Landscape structure was analyzed within a 750 m radius surrounding the studied vineyards. Arthropods were categorized into functional groups (predators, parasitoids, herbivores), and their responses to the most influencing factors were analyzed by likelihood methods and model selection. Of the total of 650 arthropods collected, 48% were predators, 33% herbivores and 19% parasitoids. Numbers of predatory aeolothrips, parasitoids and herbivorous cicadas in the study vineyards decreased with an increased proportion of vineyards in the surroundings. Spider populations in vineyards increased with increasing proportions of other agricultural fields (non-flowering crops) in the surroundings. Semi-natural elements and olive orchards had no influence on the abundance of collected arthropods. We observed synergistic effects between landscape elements and inter-row management. The total numbers of arthropods, herbivores and parasitoids in vineyards benefitted from inter-row vegetation, while spiders benefitted from bare soil. Our findings underline the importance of both surrounding landscape elements and vineyard ground cover management to promote beneficial arthropods for potential natural pest control.
... Sin embargo, actualmente existe un mayor conocimiento sobre su funcionalidad en el equilibrio ecológico de los agroecosistemas, convirtiéndose la relación de las arvenses con los cultivos en un tema de gran relevancia por su contribución al mantenimiento de las poblaciones de insectos benéficos (Altieri y Letourneau, 1982;Landis et al., 2000). En este sentido, son numerosos los estudios que evidencian la relación entre las plantas arvenses y la biodiversidad de importantes grupos de insectos benéficos en cultivos como arroz, maíz, arándano, café, trigo y uva (Powell et al., 1986;Nicholls et al., 2000;Penagos et al., 2003;Walton y Isaacs, 2011;Melón et al., 2013;Castro et al., 2017). ...
The biodiversity of beneficial insects associated with weed plants in agroecosystems of cocoa, soursop and rice was studied. Five species of weed plants associated with these agroecosystems were considered for the samplings: Crotalaria striata, Indigofera hirsuta, Hyptis capitata, Melampodium divaricatum and Stachytarpheta cayennensis. Beneficial insects were collected through systematic samplings using an entomological net, together with direct observations through a linear transect. A detailed inventory
of the community of beneficial insects associated with agroecosystems in the departamento del Meta is provided for the first time, composed of 66 species/ morphospecies. Eight species were recorded for the first time from the Orinoco basin, and two genera are new from Colombia: Myzinum (Hymenoptera: Tiphiidae) and Chaetogaedia (Diptera: Tachinidae). A high taxonomic and ecological biodiversity of beneficial insects was found to be associated with weed plants within these transformed agroecosystems, which provided supplementary trophic resources and refuge to the beneficial insects. This study provides interesting data for integrated pest management plans and ecological restoration programs, and contributes to the knowledge of the biology of the species reported
... The use of buckwheat, Fagopyrum esculentum Moench, as a cover crop has been evaluated in vineyards in New Zealand (Berndt et al., 2002), Australia (Simpson et al., 2011) and California (Irvin et al., 2016), and is recommended as a cover crop plant for enhancing natural enemies in crops grown in arid soils in the southwestern USA (Grasswitz, 2013). Buckwheat can enhance natural enemy reproduction which may concomitantly reduce pest densities (Nicholls et al., 2000;Berndt et al., 2002, English-Loeb et al., 2003, Irvin et al., 2014. Other attributes favoring the selection of buckwheat as a cover crop are inexpensive seed that is readily available and germinates easily, short sowing to flowering times, and tolerance of poor growing conditions (Angus et al., 1982, Bowie et al., 1995, Grasswitz, 2013. ...
Dispersal of natural enemies from buckwheat cover crop plots embedded within a southern California vineyard during spring and summer was investigated by using an arthropod mark-capture technique. Specifically, arthropods were marked in flowering buckwheat plots by spraying plants with a “triple mark” solution containing yellow dye, casein protein, and albumin protein. In turn, we recorded the abundance of marked and unmarked natural enemies at a gradient of distances from the treated buckwheat plots into the vineyard. Natural enemies marked with yellow dye were identified visually, while the presence of casein and albumin protein marks were detected using anti-casein and anti-albumin enzyme-linked immunosorbent assays (ELISA). The percentage of natural enemies marked with yellow dye indicated that spiders, predatory thrips (Aeolothripidae), and minute pirate bugs (Anthocoridae) dispersed 9 m (i.e., 3 rows) from marked buckwheat refuges over a six day period. The percentage of leafhopper parasitoids (Anagrus erythroneurae S. Trjapitzin and Chiappini) marked with yellow dye indicated that 22% of marked parasitoids were captured up to 18 m (i.e., six rows) to 30 m (i.e., 10 rows) from buckwheat plots up to six days after marks were applied to cover crops. Up to 17% of natural enemies marked with yellow dye, albumin, or casein were captured in non-treated control plots, suggesting that parasitoids, spiders, minute pirate bugs and predatory thrips were able to cross the 36 m buffer zones used to separate marked buckwheat plots and unmarked control plots. Results comparing the percentage of parasitoids and ‘other beneficials’ marked with a double mark (where any two of the three marks were detected) between distances in buckwheat plots indicated that double marked parasitoids were found up to 30 m (i.e., 10 rows) from buckwheat refuges, while no double marked parasitoids were captured in control plots. No triple marked arthropods were captured. To exploit the dispersal capabilities of natural enemies, these results suggest that buckwheat refuges planted in California vineyards could be planted every 6th (i.e., 18 m) or 10th (30 m) row to gain potential benefits from providing natural enemies with flowering buckwheat refuges.
... Other benefits of establishing groundcovers in the vineyard include: improved water infiltration and water-holding capacity, improved soil structure and prevention of crusts, increased fertility and organic matter, vine growth regulation, weed suppression and improved wine and juice characteristics. Cover crops are also beneficial to the environment by reduced nutrient leaching, increased biodiversity and microbial biomass, and reduced herbicide inputs (ALJIBURY AND CHRISTENSEN, 1972;BAVOUGIAN, 2014;GUERRA AND STEENWERTH, 2012;GULICK et al., 1994;LOPES et al., 2004;MONTEIRO AND LOPES, 2007;NICHOLLS et al., 2000;SMITH et al., 2008). ...
In many Midwestern vineyards a three to four-foot weed-free strip is maintained directly beneath the vines to reduce vine-weed competition. Conventionally, this strip has been conserved with repeated applications of herbicide, mainly glyphosate. The necessity for this weed-free strip to reduce vine-weed competition has been well documented in more arid climates. However, in areas with higher soil fertility and adequate rainfall, this strip may be unnecessary. Moreover, stand establishment and early vine growth have not been well documented when planting groundcovers (GC) immediately following the vine planting. The main objective of this project is to assess the severity of competition for water between ‘Edelweiss’ grapevines and neighboring permanent GC treatments. In year one (2014), the vineyard and GCs were established, where the GCs were planted immediately after the vines. Midday leaf water potential (Ψmd) measurements began in 2015 and lasted through 2017 to assess water competition between vines and GCs. Additional data collected during the four year project included: pruning weights, bud break, yield and fruit quality and soil nutrition. Generally, GC treatments had lower Ψmd than the herbicide sprayed control, however, none of the treatments exhibited even slight water stress. Vine-GC competition was most apparent in the three years of pruning weights, where the most native grass GC treatment had up to 99% in 2014, 193% in 2015 and 183% in 2016 lower weights than the control. Harvest in 2016 and 2017 showed significantly lower yields between GC treatments and the control. However, no differences were found in berry quality (pH, Titratable Acidity, °Brix). An additional greenhouse project was done to define water stress thresholds for ‘Edelweiss’ grapevines using Ψmd and high resolution thermal infrared images. Fully irrigated and 14-day dry vines exhibited a Ψmd of -8.7 bars and -13.3 bars, respectively. The grapevines exhibited a mild, moderate and severe water stress level at 8, 10 and 12 days-dry, respectively (Ψmd of -12 bars, -12.5 bars and -13 bars). Results suggest that planting groundcovers in both the alleyways and in-row areas of the vineyard during the first year of establishment is detrimental to vine growth and causes reduced yields. Advisor: Paul E. Read
... Crop diversification increases species richness, abundance and fitness of natural enemies, which can minimize pest damage and increases yield in commercial crops [8][9][10]. However, resource diversification studies usually focus only on natural enemies and how species abundance and richness are affected by attractiveness, phenology, floral accessibility, seeds, pollen and nectar production of non-crop plants [11][12][13][14][15][16]. Notwithstanding, diversity indices, richness and abundance are not sufficient to describe changes in community structure, mainly by ignoring interaction between species [17]. ...
Arthropod community composition in agricultural landscapes is dependent on habitat characteristics, such as plant composition, landscape homogeneity and the presence of key resources, which are usually absent in monocultures. Manipulating agroecosystems through the insertion of in-field floral resources is a useful technique to reduce the deleterious effects of habitat simplification. Food web analysis can clarify how the community reacts to the presence of floral resources which favour ecosystem services such as biological control of pest species. Here, we reported quantitative and qualitative alterations in arthropod food web complexity due to the presence of floral resources from the Mexican marigold (Tagetes erecta L.) in a field scale lettuce community network. The presence of marigold flowers in the field successfully increased richness, body size, and the numerical and biomass abundance of natural enemies in the lettuce arthropod community, which affected the number of links, vulnerability, generality, omnivory rate and food chain length in the community, which are key factors for the stability of relationships between species. Our results reinforce the notion that diversification through insertion of floral resources may assist in preventing pest outbreaks in agroecosystems. This community approach to arthropod interactions in agricultural landscapes can be used in the future to predict the effect of different management practices in the food web to contribute with a more sustainable management of arthropod pest species.
... In vineyards, habitat restoration and the use of summer flowering cover crops in particular has typically emphasized biological control of crop pests (Nicholls et al. 2000, Berndt et al. 2006, Irvin et al. 2016) because cultivated grapes are hermaphroditic and do not have an obligate relationship with pollinators, although it has been noted that insect pollination may lead to increased berry size and quality (McGregor 1976). For the most part, wine grape growers have expressed interest in pollinator conservation not out of concern for crop productivity, but rather as part of a broader vineyard and regional sustainability and conservation agenda (Broome andWarner 2008, Lubell et al. 2010). ...
Agricultural expansion and intensification negatively affect pollinator populations and has led to reductions in pollination services across multiple cropping systems. As a result, growers and researchers have utilized the restoration of local and landscape habitat diversity to support pollinators, and wild bees in particular. Although a majority of studies to date have focussed on effects in pollinator-dependent crops such as almond, tomato, sunflower, and watermelon, supporting wild bees in self-pollinated crops, such as grapes, can contribute to broader conservation goals as well as provide other indirect benefits to growers. This study evaluates the influence of summer flowering cover crops and landscape diversity on the abundance and diversity of vineyard bee populations. We showed that diversity and abundance of wild bees were increased on the flowering cover crop, but were unaffected by changes in landscape diversity. These findings indicate that summer flowering cover crops can be used to support wild bees and this could be a useful strategy for grape growers interested in pollinator conservation as part of a broader farmscape sustainability agenda.
... This insect only feeds on grapevine if their host plants are suppressed by herbicides [49]. In control efforts against the leafhopper Erythroneura elegantula [50], we found a deeper understanding of such switching mechanisms for predators and parasitoids from greencover crops to the grape canopy after mowing. Mowing the flowering greencover crop at a crucial moment might open new approaches to control L. botrana in viticulture by habitat management. ...
Greencover crops are widely recommended to provide predators and parasitoids with floral resources for improved pest control. We studied parasitism and predation of European grapevine moth (Lobesia botrana) eggs and pupae as well as predatory mite abundances in an experimental vineyard with either one or two sowings of greencover crops compared to spontaneous vegetation. The co-occurrence between greencover flowering time and parasitoid activity differed greatly between the two study years. Parasitism was much higher when flowering and parasitoid activity coincided. While egg predation was enhanced by greencover crops, there were no significant benefits of greencover crops on parasitism of L. botrana eggs or pupae. Predatory mites did not show an as strong increase on grapevines in greencover crop plots as egg predation. Overall, our study demonstrates only limited pest control benefits of greencover crops. Given the strong within- and between year variation in natural enemy activity, studies across multiple years will be necessary to adequately describe the role of greencover crops for pest management and to identify the main predators of L. botrana eggs.
The decline of arthropod populations observed in many parts of the world is a major component of the sixth mass extinction with intensive agriculture being one of its main drivers. Biodiversity-friendly farming practices are taking centre stage in the recovery process. In vineyards, vegetation cover is commonly used for production purposes, to reduce soil compaction by machinery use and soil erosion. Here we examined the effects of vegetation cover and soil management on the abundance of ground- (spiders, beetles, Hemiptera and harvestmen) and canopy-dwelling (wild bees, green lacewings, beetles and Hemiptera) arthropods in three categories of vineyards: (i) vineyards with no vegetation, (ii) partially vegetated (every second inter-row is vegetated) and (iii) all inter-rows are vegetated. We recorded a general positive effect of a decrease in soil perturbation intensity and corresponding higher vegetation cover on arthropod abundance. Plant species richness was the most important vegetation parameter, with a positive effect on spiders, harvestmen, hemipterans and beetles (ground and canopy) abundances. Using a path analysis, we also highlighted the central role of inter-row vegetation management in trophic and non-trophic relationships between vegetation and arthropods, and between arthropod groups. Our results demonstrate the benefits of a softer soil management preserving a diverse vegetation cover for the conservation of arthropods in Mediterranean vineyards.
The decline of arthropod populations observed in many parts of the world is a major component of the sixth mass extinction with intensive agriculture being one of its main drivers. Biodiversity-friendly farming practices are taking centre stage in the recovery process. In vineyards, vegetation cover is commonly used for production purposes, to reduce soil compaction by machinery use and soil erosion. Here we examined the effects of vegetation cover and soil management on the abundance of ground- (spiders, beetles, Hemiptera and harvestmen) and canopy-dwelling (wild bees, green lacewings, beetles and Hemiptera) arthropods in three categories of vineyards: (i) vineyards with no vegetation, (ii) partially vegetated (every second inter-row is vegetated) and (iii) all inter-rows are vegetated. We recorded a general positive effect of a decrease in soil perturbation intensity and corresponding higher vegetation cover on arthropod abundance. Plant species richness was the most important vegetation parameter, with a positive effect on spiders, harvestmen, hemipterans and beetles (ground and canopy) abundances. Using a path analysis, we also highlighted the central role of inter-row vegetation management in trophic and non-trophic relationships between vegetation and arthropods, and between arthropod groups. Our results demonstrate the benefits of a softer soil management preserving a diverse vegetation cover for the conservation of arthropods in Mediterranean vineyards.
Cover crops have long been used in agricultural production systems as a result of providing varying agronomic and environmental benefits. Although no-till (NT) is a leading approach to sustain crop production, reduce soil degradation, mitigate environmental concerns, and enhance ecosystem services, implementing cover crops can further enhance NT performance. In order to successfully adapt cover crops into NT systems, several factors should be considered. Goals should be determined based upon an individual’s farming system, as success of one approach may vary depending on climatic and environmental conditions or simply management approaches. Proper management of cover crops can lead to improved soil function and health, have agronomic and economic benefits, and enhance environmental quality. The objective of this chapter is to provide a background of cover crop management approaches and selected potential benefits in NT cropping systems.
Ecological interactions are fundamental in ecological pest management, and these interactions form networks. The properties of these networks, where interactions of all possible nature (positive, neutral, negative) coexist, are key for management, but little is known about them. The main reasons for this lack of knowledge are the difficulties in obtaining empirical evidence. These problems may be partially bypassed using a theoretical approach. Here, by means of mathematical models that represent networks of ecological interactions in agroecosystems, we characterize some architectural features that promote the self-regulation of population densities in these networks. The results show that the key features are: spatial heterogeneity and a high proportion of positive interactions.
The ultimate goal of all farmers should be to grow healthy and productive plants and animals, while maintaining the ecological integrity of the resource base of their farms. For agroecologists, such goals would translate into healthy agroecosystems exhibiting a high degree of integrity; a strong capacity to respond and adapt; and high levels of efficiency, productivity, stability, and selfdependence (Altieri and Nicholls, 1999).
Berry fruit is a thin-skinned one-celled fleshy fruit with seeds scattered through the flesh. The important berries include: Raspberries, blueberries, strawberries, blackberries and cranberries. Most of the berry fruits depend upon or benefit from bee pollination, but pollinators are adversely affected due to insecticides used for controlling pests. It is therefore important to devise a pest management system to provide safety to pollinating insects for quality and quantity of berry production. Several studies have been conducted on the role of pollinating insects and management of insect pests on berry fruit production. Information on some of the important berry fruits is discussed below:
Following a request from the European Commission (EC), the European Food Safety Authority (EFSA) initiated a procedure for the evaluation of data supporting the necessity of the application of insecticide active substances to control a serious danger to plant health within the context of Article 4(7) of Regulation (EC) No 1107/2009. EFSA established an ad hoc working group (WG) who proposed a methodology for conducting this type of evaluation. The draft protocol was circulated among European Union Member States (MS) for commenting. The aim of this protocol is to enable a consistent and transparent evaluation of submissions made by applicants in accordance with the derogation detailed in Article 4(7) of Regulation (EU) No 1107/2009 to confirm the lack of other available means capable of controlling an identified serious danger to plant health. All the evaluations are made for each specific crop/pest combination separately for which a derogation is requested. Usually, derogation for the use of an insecticide active substance is not scientifically supported if an alternative control programme not requiring the application of an insecticide can manage the specific crop/pest combination under consideration, or if another active substance with the same mode of action (IRAC) as the active substance under consideration is available. If these conditions are not verified, the process moves to the evaluation of: 1) the risk of resistance associated to the different mode of action of all active substances that are authorised in the MS; 2) the risk of resistance associated to the different pests; 3) the availability of non-insecticide alternatives.
In 1980 the variegated leafhopper (VLH), Erythroneura variabilis, invaded California's San Joaquin Valley, and has since rapidly increased in numbers to become a major pest in vineyards. Correlated with the invasion by VLH are declining populations of congeneric grape leafhopper (GLH), E. elegantula. This paper explores interspecific competition and shared parasitism as possible reasons for this decline in GLH. Although interspecific competition between VLH and GLH was evident in field-cage experiments, its effects were equivalent to instraspecific competition. Instead of simple direct competition explaining the replacement of GLH by the invading VLH, the key appears to be parasitoid that is shared by two leafhoppers. In particular, the native GLH experiences higher attack rates from the shared parasitoid (Angarus epos) than does the invading VLH. This differential parasitism apparently shifts the competitive balance from one of equality to a strong disadvantage for the native relative to the invader. This is the first study, to our knowledge, to document the importance of parasitoid-mediated indirect effects in an invasion.
In 3 of 4 vineyards we studied, late-season leafhopper density was lower on vines
in cover cropped plots than in plots with no cover crops. However, the level of leafhopper
reduction (about 15%) was rarely economically important and the mechanisms leading
to reduction were not clear. For example, there were few differences in the number
of leaf hopper predators or parasitoids on the vines in cover cropped versus no cover
plots. However, there were significant between-treatment differences in vine growth.
Plots with seasonwide maintenance of a cover crop and resident grasses had a reduction
in vine vigor. Lower vine vigor has been associated with lower leafhopper densities
and, in our studies conducted from 1993 to 1996, those plots with reduced vine vigor
often had the greatest reduction in late-season leafhopper density.
Metaseiulus occidentalis (Nesbitt), a predatory mite, is better able to regulate low densities of willamette mites, Eotetranychus willamettei Ewing, in more complex communities. Willamette mite populations fluctuate more widely in amplitude in simple communities or where monoculture is practiced. Weedy grasses associated with grapevines increase chances for reliable and stable spider mite population control because potentially capable predators are maintained well dispersed in the community by the presence of alternate prey.
Manipulation of ground cover vegetation in apple orchards and vineyards had a substantial impact on the abundance of soil dwelling and foliage inhabiting arthropods. Systems with cover crops were generally characterized by lower densities of phytophagous insects, less fruit damage caused by insects on the trees, larger populations and more species of natural enemies and increased predation of artificial prey. Cover crops that remained in full bloom throughout the season, that produced more biomass and supported higher numbers of alternate prey, seemed to harbor the largest complex of predators and parasites. Apparently, cover crop manipulation can directly affect colonization of insect pests which discriminate among trees with and without cover beneath, and can also help retain populations of soil and foliage inhabiting natural enemies through the provision of alternate food and habitat. The design of proper cover crop-orchard mixtures can result in enhanced biological control of specific pests in existing orchards and vineyards.
A frequently cited habitat diversification tactic is the use of prune tree refuges that support overwintering populations of Anagrus epos (Girault), a mymarid egg parasite of the western grape leafhopper, Erythroneura elegantula Osborn, in vineyards. Here we test the effect of prune trees on early-season abundance of adult A. epos in vineyards. A. epos was found in vineyards downwind of prune trees at more than twice the densities of vineyards lacking prune trees, despite significant variation in A. epos immigration from sources outside the pnme tree-vineyard system. Densities of A. epos overwintering within prune trees explained a significant amount of the variation in A. epos trap capture in vineyards. Furthermore, another factor associated with prune trees was found to influence A. epos abundance in vineyards: a windbreak effect created by the prune trees concentrated dispersing A. epos on the leeward side of the prune trees, thereby further enhancing A. epos numbers.
Populations of waln ut aphids and associated insects were observed over a four year period in several northern California walnut orchards. Temperature, leaflet age, amount of prior aphid feeding and coccinellid predation were found to be the most important factors influencing walnut aphid population changes. Sharp declines in aphid population levels were correlated with high temperatures, especially when several days occur with maxima over 100^@?F. Temperatures may also affect aphids indirectly by directly affecting coccinellid beetles. Early spring temperatures influence the leafing out of the walnut trees. Cool spring temperatures can delay the leafing out of trees, thus postponing the aphid population increase. Carrying capacity of a leaflet for aphids is defined as a maximum number of aphids that can exist on a leaflet at any one time. This level appears to be determined by factors, other than space. Orchards in different areas and of various varieties, irrigation practices, and general vigor exhibit different carrying capacities for aphids. Factors which influence these levels are age of the leaflet and the amount of prior aphid feeding which has occurred on them. Coccinellid beetles were the most important predators encountered in the study. Examples are discussed where the following conditions prevailed: (1) where coccinellids were not involved, (2) where coccinellid population numbers trailed the aphid number and contributed only by shortening the time during which aphids were at maximal population levels, (3) where coccinellids lengthened the time required for the aphids to reach carrying capacity levels, and in so doing reduced the actual carrying capacities to some degree, (4) where coccinellids were the key factors regulating aphid numbers. Aphid parasitism was not important.
A review of entomological studies of cover crops for tree nuts, pome fruits, stone fruits, and citrus suggests both opportunities and challenges. Various cover crops harbor distinctive complexes of beneficial and pest arthropods, and diverse trophic relationships have been well documented in the literature. More study is required to determine: (1) whether cover cropping modifies orchard microclimate and target crop nutritional status and thereby influences pest dynamics; (2) whether and how cover crop species composition, spatial interspersion of species, and management by irrigation, mowing, and tillage affect build-up and movement of arthropods, and resultant pest damage to the target crop.
Collards were grown at Ithaca, New York, in two experimental habitats: pure stands and single rows that were bounded on each side by diverse, meadow vegetation. The arthropods associated with these plants were sampled on 20 dates over a 3-year period. The status of the herbivore species was measured by their rank in biomass in each sample. The two most prominent species, Phyllotreta cruciferae and Pieris rapae, maintained high status throughout the investigation, but another important species, Brevicoryne brassicae, was absent for an entire season. Pit feeders usually formed the most important herbivore guild. Nevertheless, the guild spectrum, which describes the functional structure of the fauna, varied widely in time and space. The size distributions of species and of individuals were both highly skewed toward the smaller sizes. Herbivore loads, the mean biomass of herbivores per 100 g of consumable foliage, were consistently higher in the pure stands. Moreover, herbivore loads varied significantly with season in each experimental habitat. Both the number of herbivore species and the diversity of the herbivore load were greater in the diverse habitat. Biomass was more heavily concentrated among the prominent herbivores in the pure stands; increased dominance, rather than differences in species richness, appeared to be the major cause for the lower herbivore diversity in this habitat. The diversity of predators and parasitoids was higher in the pure stands. Most of the abundant species found on collards shared a similar narrow range of hosts. As a result the species in this core group of herbivores and parasitoids were regularly associated with each other. Predators and the less abundant herbivores tended to be less specialized and served to link the collard association with the surrounding community. Plant-arthropod associations are representative of component communities, well-integrated systems that form portions of larger compound communities. This distinction facilitates the analysis of community structure. Microclimates and the effectiveness of @'enemies@' did not appear to differ sufficiently in the two experimental habitats to account for the observed differences in the herbivore load. The results suggest a new proposition, the resource concentration hypothesis, which states that herbivores are more likely to find and remain on hosts that are growing in dense or nearly pure stands; that the most specialized species frequently attain higher relative densities in simple environments; and that, as a result, biomass tends to become concentrated in a few species, causing a decrease in the diversity of herbivores in pure stands.
A major objective of insect ecology is to explain observed patterns of interaction between plants and herbivorous insects. We would like to understand both how such patterns are maintained in ecological time and also how they have come about in evolutionary time. A test of how far such understanding has progressed will be our ability to predict how patterns vary from one kind of community to another and how they will change when subjected to natural or human disturbance.
Pseudoreplication is defined as the use of inferential statistics to test for treatment effects with data from experiments where either treatments are not replicated (though samples may be) or replicates are not statistically independent. In ANOVA terminology, it is the testing for treatment effects with an error term inappropriate to the hypothesis being considered. Scrutiny of 176 experimental studies published between 1960 and the present revealed that pseudoreplication occurred in 27% of them, or 48% of all such studies that applied inferential statistics. The incidence of pseudoreplication is especially high in studies of marine benthos and small mammals. The critical features of controlled experimentation are reviewed. Nondemonic intrusion is defined as the impingement of chance events on an experiment in progress. As a safeguard against both it and preexisting gradients, interspersion of treatments is argued to be an obligatory feature of good design. Especially in small experiments, adequate interspersion can sometimes be assured only by dispensing with strict randomization procedures. Comprehension of this conflict between interspersion and randomization is aided by distinguishing pre-layout (or conventional) and layout-specific alpha (probability of type I error). Suggestions are offered to statisticians and editors of ecological journals as to how ecologists' understanding of experimental design and statistics might be improved.
The ecosystem approach to plan and implement integrated plant protection in viticulture of eastern Switzerland
- E F Boller
Boller, E.F. (1990) The ecosystem approach to plan and implement
integrated plant protection in viticulture of eastern Switzerland.
Can we manipulate leafhopper densities with management practices
- K M Daane
- M J Costello
- G Y Yokota
- W J Bentley
Daane, K.M., Costello, M.J., Yokota, G.Y. & Bentley, W.J. (1998) Can
we manipulate leafhopper densities with management practices?.
Grape Grower, 30 (4), 18±36.
Can we manipulate leafhopper densities with management practices?
- Daane K.M.