No full-text available
To read the full-text of this research,
you can request a copy directly from the author.
Environmental Issues Involved in Biological Control of Rangeland Grasshoppers (Orthoptera: Acrididae) with Exotic Agents
Abstract
Within the field of biological control, there is a strategy that involves the attempt to control a native pest species with an exotic biological control agent. This strategy has been termed neoclassical biological control, and its ecological foundation differs markedly from other forms of biological control. Neoclassical biological control with a parasitic wasp and an entomophagous fungus from Australia is now being applied to rangeland grasshoppers in the western United States. Available evidence suggests that the costs of such a strategy greatly exceed the benefits. Although the probability of successful establishment may be low, if such an agent is established there are a number of possible nontarget impacts. Adverse effects include competitive suppression or extinction of both native biological control agents and nontarget acridids, which comprise the vast majority of extant grasshopper species. Suppression of nontarget acridids may result in loss of biological diversity, existing control of weed species, release of otherwise innocuous acridid species from competitive regulation, disruption of plant community structure, suppression of essential organisms vectored by grasshoppers, and disruption of food chains and other nutrient cycling processes. These impacts are particularly serious given that an established exotic agent is essentially permanent and spatially unbounded. Given that the value of the rangeland resource depends upon the largely unknown ecological processes that underlie its sustainable productivity, there are a number of management techniques that offer a greater probability of success with a markedly lower likelihood of ecological and economic disruption than does neoclassical biological control.
... The vital role that grasshoppers play in enhancing the biodiversity of agricultural regions grasslands [2] and deciduous woods which role in biodiversity [14] Grasshoppers are important to the environment [15] not just because they are the main herbivores [16] but also because they are an important link in food chains [17] , affecting a variety of animals such as birds, spiders, and reptiles [18] . Thus, appreciating the seasonal distribution and systematics of Acrididae [19,20] is not just an academic endeavor but also an essential step in understanding and maintaining the fragile environmental balance. ...
... Thus, appreciating the seasonal distribution and systematics of Acrididae [19,20] is not just an academic endeavor but also an essential step in understanding and maintaining the fragile environmental balance. Grasshoppers, especially those in the Acrididae family, are quite problematic in the agricultural setting [15,21] . The significance of these pests economically, highlighting their potential to seriously harm pastures and crops [22] . ...
... Native isolates performed slightly better as endophytic colonists than commercial ones in our review. Likewise, Lockwood (1993) preferred indigenous isolates for microbial control in consideration of environmental and ecosystem safety. Additionally, exotic species may not establish due to competition from native species or if they do establish, they may diminish or displace native species, leading to a loss in biological diversity. ...
... In our meta-analysis, of the 25 plant species reported to be colonized by endophytic B. bassiana isolates, the percent colonization was greatest on faba bean. However, most studies were conducted on maize, which was one of the first crops reported to successfully establish B. bassiana as an endophyte following artificial inoculation (Bing and Lewis, 1991;1992a;1992b;1993). Gonz alez-Mas et al. (2021) showed that cotton was a less suitable host plant for B. bassiana than tomato and melon; however, the passage of the fungus through cotton improved endophytic activity and higher colonization rates were achieved in a subsequent colonization experiment. ...
The insect-pathogenic fungus Beauveria bassiana (Bb) colonizes several plant species as an endophyte. However, the diversity of plants colonized and the extent of colonization by this fungus have not been summarized comprehensively across all plant species. To fill this knowledge gap, a meta-analysis of published studies (years 2002–2018) on the percentage of B. bassiana plant colonization across the plant kingdom was conducted. We collected 232 published papers from which 1,051 studies (individual treatments) were extracted and analyzed with Comprehensive Meta-Analysis, Version 3 (CMA) software. Factors (n = 26) influencing plant colonization by B. bassiana were identified. Across all studies, the mean endophytic colonization of B. bassiana was 29% in different plant taxa. Plant colonization by B. bassiana was highest for isolates collected from insects. Most studies applied B. bassiana at 1 × 10⁸ conidia/ml; however, plant colonization was greatest with an application rate of 1 × 10¹² conidia/ml. Among all plant hosts, colonization percentage was highest in faba bean, plants in the family Brassicaceae, angiosperms (eudicots, annuals), plants classified with a forb/herb/vine growth habit, and plants with fibrous or tap root systems. As an inoculant, B. bassiana was most frequently applied to the whole plant after true leaves had developed. The foliar spray was the most studied inoculation method, but the application of solid grain substrate to foliage gave higher plant colonization. Studies conducted in controlled environments resulted in higher endophytic colonization with B. bassiana than field studies. Endophytic B. bassiana presence was confirmed primarily with microscopy, rather than molecular methods. High heterogeneity (I² = 97%) across studies was identified with large variability in endophytic B. bassiana colonization across a diversity of plant species. These findings increase our understanding and knowledge of the endophytic lifestyle of B. bassiana, which will facilitate the development of novel, sustainable, and eco-friendly disease management strategies with B. bassiana.
... Classical biological control is the introduction of co-evolved natural enemies (parasitoids, predators, and pathogens) from the pest's native range to manage invasive pests of exotic origin (Lockwood 1993). Classical biological control has been most successful when the pest and its natural enemy have a close ecological relationship, such that the natural enemy is a specialist on the target pest (Hoddle 2002). ...
... Lastly, most of the introduced BCAs were generalists with a broad host range. While some of these generalist BCAs included CRB or another Oryctes species in their host range, others had no co-evolutionary history with CRB and were effectively new associations, an approach sometimes termed as the neoclassical biological control (Hokkanen and Pimentel 1989, Lockwood 1993, Ehler 2000. Potential nontarget impacts from these BCAs on biological communities and environments of the introduced area were also never considered (Howarth 1991, Sands andVan Driesche 1999), reflecting what was common practice for biological control at that time. ...
The coconut rhinoceros beetle (CRB: Oryctes rhinoceros Linnaeus) is one of the most damaging pests to coconut and oil palms in Asia and the Pacific Islands. Adults bore into the crown and damage developing fronds, which affects tree development and yield. The insect is native to South and Southeast Asia and was inadvertently introduced into the Pacific in 1909. It has since spread to several Pacific island nations and territories , causing significant economic impact on these important coconut and palm-growing regions. In the 1950s and 1960s, an international biological control effort was initiated to search for and release natural enemy species. Release of the Oryctes rhinoceros nudivirus Huger (OrNV) and the species complex of Metarhizium Sorokin (Hypocreales: Clavicipitaceae) was successful in controlling CRB in its invaded range. Recently a new biotype of the beetle, known as CRB-G, has spread into the Pacific Islands causing unprecedented levels of damage due to the failure of previously successful biological control agents (BCAs) to suppress this biotype. The re-emergence of CRB as a serious pest warrants a rigorous re-evaluation of potential BCAs and a new search for effective natural enemies if necessary. In this article, we review literature on CRB to 1) analyze past introductions of BCAs and their effectiveness; 2) identify potentially important natural enemies and their geographical origins; and 3) assess possible approaches for utilization of BCAs against the new wave of CRB invasion. Research gaps and directions deserving future attention are highlighted and a strategy for renovation of biological controls for CRB suggested.
... Environmental safety and ecosystem stability considerations lead to the conclusion that the use of native isolates in a microbial control program is more convenient (Lockwood 1993) [10] . Also, mycoinsecticides may be most effective in pest managements programmes integrating beneficial arthropods, or in greenhouse crops where favourable environmental conditions (high humidity and low UV exposure) can be manipulated (Jacobson et al., 2001) [7] , (Down et al., 2009) [3] . ...
... Environmental safety and ecosystem stability considerations lead to the conclusion that the use of native isolates in a microbial control program is more convenient (Lockwood 1993) [10] . Also, mycoinsecticides may be most effective in pest managements programmes integrating beneficial arthropods, or in greenhouse crops where favourable environmental conditions (high humidity and low UV exposure) can be manipulated (Jacobson et al., 2001) [7] , (Down et al., 2009) [3] . ...
Investigations were carried out to evaluate the efficacy of formulations of Beauveria bassiana (Bb 112) against whitefly, Bemisia tabaci on tomato under microplot condition. Among the different formulations tested viz., crude, talc and oil formulations, B. bassiana (Bb 112) oil formulation was most effective against whitefly on tomato with 45.86 % reduction in population over control followed by talc (29.62 %) and crude formulations (21.63 %). Present study wide open the scope of using an oil formulation of B. bassiana (Bb 112) against other sucking pests also.
... (6) Biocontrol is easily established (7) BCAs are frequently very host specific. ...
... (3) With biocontrol, there is the possibility that the BCA may tend to feed on the desired plants or insect, that is, crossovers [7][8][9]. Careful selection of the BCA will minimize this problem. ...
Parasites (ectoparasites or endoparasites) are a major cause of diseases in man, his livestock and crops, leading to poor yield and great economic loss. To overcome some of the major limitations of chemical control methods such as rising resistance, environmental and health risks, and the adverse effect on non‐target organisms, biological control (biocontrol) is now at the forefront of parasite (pests) control. Biocontrol is now a core component of the integrated pest management. Biocontrol is defined as “the study and uses of parasites, predators and pathogens for the regulation of host (pest) densities”. Considerable successes have been achieved in the implementation of biocontrol strategies in the past. This chapter presents a review of the history of biocontrol, its advantages and disadvantages; the different types of biological control agents (BCAs) including predators, parasites (parasitoids) and pathogens (fungi, bacteria, viruses and virus‐like particles, protozoa and nematodes); the effect of biocontrol on native biodiversity; a few case studies of the successful implementation of biocontrol methods and the challenges encountered with the implementation of biocontrol and future perspectives.
... No negative environmental impacts of introduction of the Australian pathotype of E. grylli have been observed, but concern about the impact of this pathogen on non-target grasshopper species has emerged. Lockwood (1993) argued that because 85 % of grasshopper species in North America are either beneficial or harmless, they must be regarded as non-target organisms . Permanent suppression of these populations could result in loss of biodiversity and impinge on the natural control of weedy species, resulting in the disruption of native plant community structure. ...
... Permanent suppression of these populations could result in loss of biodiversity and impinge on the natural control of weedy species, resulting in the disruption of native plant community structure. In addition, the introduced pathotype could competitively suppress native E. grylli pathotypes, or even, in a worst-case scenario, cause their extinction (Lockwood 1993). Carruthers and Onsager (1993) rebutted Lockwood 's views arguing that the pathotype introduced from Australia has a limited host range, even within Acrididae, and would not affect all of the non-target acridid species. ...
Microbial control agents offer a method of pest control using organisms that are a natural component of the environment and are usually much more selective than chemical pesticides. Furthermore, they can usually be integrated with other methods of control, and may provide prolonged control by establishment within the host population. However, microbial control agents also possess properties that can pose human and environmental risks depending on the nature of the pathogen and its pattern of use. We present an overview of issues concerning the safety and registration of microbial control agents with emphasis on pathogens of locusts and grasshoppers. The potential safety issues and other consequences of concern from the deployment of microorganisms for pest control are: (1) pathogenicity to non-target organisms, (2) toxigenicity to non-target organisms, (3) competitive displacement of microorganisms, and (4) allergenicity. Inundative control methods pose unique risks because the pathogens must be produced in large quantities, stored, transported, and applied, usually in concentrations much higher than would normally ever occur naturally. The overriding concern in introducing an exotic agent is the risk to non-target beneficial organisms, because once the agent becomes established, it will in most situations be impossible to eradicate. However, if indigenous organisms are used, there is relatively little risk of irreversible, long-term detrimental effects. A synopsis of safety testing results of some of the more promising microbial control agents for grasshoppers and locusts and an evaluation of their potential hazards are presented. Safety to vertebrates is evaluated by a tiered series of laboratory test requirements. Assessments on hazards to non-target invertebrates are based principally on results of laboratory bioassays. Safety tests should be chosen with regard to the biological characteristics of the agent and should not impose standards that are more stringent than those imposed on other forms of pest control. Regulatory oversight should assure the integrity of the environment and safety of the public, while at the same time not unduly hampering the development, registration, and use of more sustainable pest control methods.
... Despite its paramount significance, the isolation and identification of entomopathogenic fungi that infect pests in citrus orchards, have been inadequately investigated in northern Iran (Naeim Amini et al. 2010;Karimi and Kamali 2021). Moreover, the efficacy of a regionally developed fungal biopesticide may vary in different countries and locations due to differences in fungal races, environmental conditions, and ecological characteristics (Lockwood 1993;Goble et al. 2010). Therefore, it is crucial to isolate and identify indigenous entomogenous fungi to enhance understanding of the natural biodiversity in specific areas and to establish a valuable source of biological control agents for future pest management purposes (Quesada-Moraga 2007;Jacas and Urbaneja 2010;Dreistadt 2012;Bouvet et al. 2019). ...
Entomopathogenic fungi play a significant role in regulating insect populations in nature and have potential applications in pest management strategies in different regions. Citrus spp. are among the important horticultural products in northern Iran, and the orchards are affected by different insect pests, especially mealybugs. This study aimed to isolate and identify entomopathogenic fungi associated with citrus orchard pests in northern Iran, focusing on Akanthomyces and Lecanicillium species on mealybugs. Through the samples collected from different regions within Guilan province, 12 fungal isolates were collected and identified based on the combination of morphological characteristics and molecular data. Akanthomyces lecanii, A. muscarius, Engyodontium rectidentatum, Lecanicillium aphanocladii and Lecanicillium rasoulzarei sp. nov. were identified. Of these, A. muscarius on Lepidosaphes sp., E. rectidentatum on Coccidae, and L. aphanocladii on Tetranychus urticae are reported as new fungal-host records from Iran. Moreover, a new species, Lecanicillium rasoulzarei, is illustrated, described, and compared with closely related species.
... Several prominent biological control researchers provided assurances that biological control was environmentally safe and risk-free [21]. This view was not shared universally by scientists, but, in particular, the environmental safety of biological control was questioned [22][23][24][25][26]. It was pointed out that in comparison with the application of pesticides, biological control is irreversible, self-perpetuating and self-dispersing, attributes clearly considered among the benefits of biological control by some, but factors alerting others to the potential environmental implications of such introductions. ...
Biological control is an important component of pest management systems. It was generally considered safe and sustainable until the validity of this consensus was challenged by researchers who pointed out that there was a lack of study, and hence evidence, to support it and provided examples of non-target impacts. Biosafety of biological control subsequently received considerable attention from both biocontrol practitioners and regulators. Many countries now have legislation in place, which is focused on risk assessment for biological control and protecting native and valued biota and the environment from potential adverse impacts. This review summarizes the biosafety debate and characterizes the direct and indirect risks of biological control mainly for weeds and insect pests. During a biological control programme, there are several ways in which aspects of biosafety can be considered and addressed: exploration in the native range of the target species; from literature and knowledge of the biological control agent and host; experience from use of the biological control agent elsewhere; and host-range tests. The value of post-release monitoring and retrospective studies for validation of pre-release predictions is discussed. A poorly studied aspect is analysis of the population impacts of non-target attack by biological control agents. The literature from the last 20-30 years can help define some useful principles by which a risk assessment can be conducted to minimize adverse environmental effects. It has become clear over this period that comprehensive assembly of information and robust quarantine testing to provide a well-structured risk assessment can reduce uncertainty in decision-making in this area.
... A corollary is that other harmful or beneficial species may increase in abundance. Such events could lead to loss of biological diversity, loss of existing biocontrol, release of species from competitive regulation, disruption of plant community structure, suppression of organisms essential to ecological integrity, and disruption of food chains and nutrient cycling (Lockwood 1993). Finding and determining selectivity of a potential biocontrol organism is a demanding research task, but it may pale in comparison to determining if the selected species will be successful in the chosen habitat. ...
... Many tests concerning the biosafety of fungi and other microbes used as biocontrol agents have been conducted to get information related to their toxic characteristics, environmental safety such as the effect on the stability of the ecosystem because of their persistent nature (Zimmermann, 1993). Additionally, the entry of exotic strains should be questioned (Lockwood, 1993). To appraise the precarious health effects on humans, in vivo studies have been performed on mice and rabbits using several Mexican fungal strains (Mier et al., 2005;Brunner-Mendoza et al., 2017). ...
Locusts (Orthoptera: Acrididae) are historically proven insect pests of agricultural crops growing around the globe. Their management is crucial to food security throughout the world that needs governmental/international participation. Locusts exhibit solitary phase at low population density and gregarious phase at high population density. Gregarious hoppers gather and march in dense bands, and adults swarm in large numbers to long distances causing huge damage to various major and minor crops, such as fruits, vegetables, legumes, and cereals across the globe. This damage to vegetation results in great economic losses. Several conventional methods have been employed for the management of locust outbreaks. However, these methods are expensive, less effective, and of short-term use. Furthermore , the use of insecticides poses threat to the natural enemies of locusts Locust Outbreaks: Management and the World Economy. Umair Riaz, Khalid Rehman Hakeem, (Eds.)
... Environmental safety and ecosystem stability considerations lead to the conclusion that the use of native isolates in a microbial control program is more convenient (Lockwood, 1993). Moreover, mycoinsecticides may be most effective in pest management programmes integrating beneficial arthropods, or in greenhouse crops where favourable environmental conditions (high humidity and low UV exposure) can be manipulated (Jacobson et al., 2001;Down et al., 2009). ...
The investigations were carried out on the shelf life of oil based formulation of B. bassiana (Bb 112) under different storage conditions. The formulation stored under ambient temperature (28 ± 2°C) recorded 587.00 and 216.66 × 108 CFU ml-1, respectively on the day of preparation and after 28 weeks of storage. Pathogenicity
tests were performed with oil based formulation of B. bassiana (Bb 112) stored at ambient temperature against S. dorsalis and P. latus. LC50 values against S. dorsalis and P. latus revealed that formulation showed highest virulence with the lowest LC50 values of 1.58 × 105 and 5.20 × 106 spores ml-1, respectively. LT50 values of oil based formulation of B. bassiana (Bb 112) against S. dorsalis and P. latus showed the lowest LT50 value of 78.79 h and 83.39 h, respectively.
... En este libro utilizaremos principalmente los términos que se aplican con mayor frecuencia en la literatura: control biológico natural, por conservación, clásico y aumentativo. Acciones humanas que protegen y estimulan el rendimiento de organismos benéficos naturales Control biológico clásico (CBC) (Greathead, 1994) Control biológico por inoculación (van Lenteren, este capítulo); Control de importación (Nordlund 1996) Introducción de un número relativamente bajo de organismos benéficos del área de origen de la plaga con el objetivo de obtener un control permanente Control biológico aumentativo (CBA) (DeBach, 1974) Producción masiva y liberación periódica de organismos benéficos sin el objetivo de obtener un control permanente Control inundativo (van Lenteren, 1986) Liberación periódica de grandes cantidades de organismos para obtener un control inmediato de plagas en cultivos con un ciclo de producción corto Control de inoculación estacional ( van Lenteren, 1986) Liberación periódica de cantidades relativamente bajas de organismos para obtener control durante varias generaciones de plagas en cultivos con un ciclo de producción largo Casos especiales de control biológico clásico Control fortuito (CF) (DeBach, 1974) Control de una plaga por un organismo benéfico introducido accidentalmente Control biológico neoclásico (Lockwood, 1993) Nuevo control de asociación (Hokkanen y Pimentel, 1989) Utilización de organismos benéficos exóticos para controlar una plaga nativa ecosistemas agrícolas, en la tierra y en el agua. Desde el punto de vista económico, es la mayor contribución a la agricultura (Waage and Greathead, 1988). ...
Se tienen registros de que el control biológico con agentes de control, tanto microbianos como enemigos naturales de los artrópodos, ha sido utilizado desde el año 1895 en América Latina y en el Caribe, y en la actualidad es utilizado en gran escala. En este Capítulo se presenta información acerca de la historia y la situación actual del control biológico en esta región, la que cabe aclarar, no fue fácil de rastrear. Así, se enumeran las organizaciones que se dedican en el biocontrol en esta región. A esto le siguen descripciones de distintas estrategias de control biológico, esto es, natural, por conservación, clásico y aumentativo, con algunos ejemplos regionales. Luego, se hizo un enfoque para encontrar, evaluar y utilizar agentes de control biológico como orientación para proyectos de investigación. A menudo, pueden encontrarse de diez a cien candidatos de control biológico asociados a una plaga. Un enfoque de investigación bien organizado, utilizando criterios de evaluación puede permitir una rápida exclusión de especies candidatas inapropiadas o problemáticas. La investigación en control biológico tiene fondos limitados y la rápida eliminación de los candidatos inadecuados da como resultado la utilización del presupuesto en candidatos prometedores. Los reglamentos acerca de la importación y liberación de agentes que se han implementados durante los últimos 30 años son resumidos en este capítulo. Como consecuencia de la aplicación de estas regulaciones, se observa que la prospección de enemigos naturales exóticos se ha vuelto muy difícil y por lo tanto hay menos agentes de control biológicos nuevos disponibles. Finalmente, se brinda el delineamiento de la estructura del libro.
... 12. The expression neoclassical biological control was coined by Lockwood (1993Lockwood ( , 1996 to explain a subset of the controversial kind of biological control advocated as "new associations" by Hokkanen and Pimentel (1984). There is controversy for two reasons. ...
IPM-143, a 12-page glossary by J. H. Frank and J. L. Gillett, attempts to prevent the spread of inaccuracy and confusion by providing definitions for a number of expressions used in biological control literature. Controversial terms are supplemented with discussion in footnotes. Includes references. Published by the UF Department of Entomology and Nematology, August 2006. IPM-143/IN673: Glossary of Expressions in Biological Control (ufl.edu)
... Many birds could prey upon arthropods in agroecosystems, strengthening unknown ecosystem services in rural areas (Jirinec et al. 2011). Insects, such as orthopterans, are considered agricultural pests (Lockwood 1993;Carruthers and Onsager 1993) and the current study found orthopterans to be the most frequent prey item of the Burrowing Owl and the American Kestrel in the study area. Furthermore, kestrels and owls could be part of the control of increased populations of rodents Norrdahl 1989, 1998;Kay et al. 1994). ...
We analysed the diet of the Burrowing Owl (Athene cunicularia) and the American Kestrel (Falco sparverius) in a fragmented habitat and natural surroundings in the arid ecosystem of the Baja California peninsula, Mexico. Both small-sized raptors are considered in the same trophic guild, and as keystone species, interactions between them could be of interest for wildlife management in fragmented landscapes for agricultural activities. The diet analysis of these top predators could be a good monitor of prey abundance, some of which may be considered detrimental for agricultural activities. Prey frequencies in owl pellets were higher for arthropods (53.1%) and rodents (32.4%), but rodents were the most abundant item in terms of biomass (34.5%). Arthropods also showed higher relative frequencies in kestrel pellets (36.4%), but reptiles were the second in order of importance (28.4%) and contributed the most (64.7%) to the total prey biomass. The biomass contribution (66.1%) of vertebrates in the diet of the Burrowing Owl was lower than for the American Kestrel (95.6%) in a fragmented habitat area. Most prey types were present in the diet of both raptors, but we found significant differences in the biomass contributions of each category. Reptiles and rodents were the prey items that contributed most to the differences in the raptors’ diets, in terms of biomass (33% and 20.3%, respectively). Close nesting surroundings (0.5 km and 1 km radius) evidenced a higher proportion of natural vegetation in the kestrel’s (50.6% and 38.9%, respectively) than in owl’s potential home range (25.8% and 16.4%). The differences in diet suggest some degree of niche partitioning of these species likely due to the more flexible owl’s nesting habitat requirements and to the extended nocturnal activity of the species. These results reflect the capability of being complementary species, both exploiting some pests that are harmful for agriculture, and evidencing the importance of both species as regulators of agro-ecosystems in the peninsula of Baja California.
... While such adverse effects were recognized long ago, they were dismissed as being of little regard to society (Perkins 1897). This period featured the influential papers by Howarth (1991), Lockwood (1993) and Simberloff and Stiling (1996a, b) that strongly implicated BCAs as causes of adverse environmental effects. These criticisms further reinforced the view that specialists were superior classical BCAs because they were less likely to cause adverse environmental effects than generalists, due to their narrow host range. ...
Exotic generalist arthropod biological control agents (GABCAs) have been historically marginalized in classical and augmentative biological control due to their broad diet breadth, but an increasing demand for a more sustainable pest control is encouraging their reconsideration. This special issue compiles a collection of papers revealing that risks of several exotic GABCAs were overestimated, not all generalists are riskier than specialists and their environmental risk assessment (ERA) solely based on exposure analysis is inadequate. Three papers demonstrated that generalists were not involved in predicted non-target interactions: generalist idiobiont parasitoids probably do not exhibit interference competition with each other, an oligophagous exotic egg-larval koinobiont parasitoid does not compete with a native larval koinobiont, and an invasive generalist predator does not escape from its enemies. Two innovative methods for selecting non-target species are proposed, one based on existing food web data to predict indirect non-target effects, and the other on functional traits to predict competition with native natural enemies. Also a comprehensive GABCA-ERA method is proposed that integrates adverse effect analysis to the ‘conventional’ exposure analysis. The method was scrutinized by two studies: one suggesting that it could have resulted in faster and less costly decisions on two exotic generalists in New Zealand, and the other suggesting that eight exotic GABCAs released in Argentina might potentially reduce native natural enemies. We hope this special issue will stimulate the continued advance in the biosafety research of GABCAs so their safe use does not stagnate.
... These swarms also cause scarcity of food for many animals, thus affect biodiversity (Latchininsky 2008). They are potentially useful bioindicators for land management (Andersen et al. 2001;Saha and Haldar 2009;Branson and Sword 2010) due to species richness and abundance (Lockwood 1993;Armstrong and Hensbergen 1997;Meyer et al. 2002;Branson et al. 2006;Rocha et al. 2010) ease of sampling and sensitivity to environmental disturbances (Andersen et al. 2001). Tandon and Shishodia (1976) have reported 16 species under 15 genera and two families of Superfamily Acridoidea from Grahwal region, Uttarakhand. ...
Acridoids, commonly known as grasshoppers and locusts, are cosmopolitan, hervivorous, notorious pests of agricultural crops, potential bio-indicators for land management and one of the most dominant groups of class Insecta. This is the first report on diversity and distributional pattern of these insects from Terai region of Uttarakhand. Present explorations were made to know species diversity, species compostion, abundance and distributional pattern of Acridoid fauna in Udham Singh Nagar, Terai region of Uttarakhand, India. A total number of 847 specimens of acridoids were collected from seven different sites of Udham Singh Nagar having 22 species and 14 genera belonging to 2 families, 7 subfamilies, and 11 tribes by sweep net and hand picking method during the survey period 2017–2018. Family Acrididae was found to be more diverse with 20 species (87%) followed by family Pyrgomorphidae with only 3 species (13%). Among subfamilies of family Acrididae, the subfamily Oxyinae was found to be most abundant and Gomphocerinae was least abundant. On the basis of number of genera, subfamily Oedipodinae was most dominant, followed by Catantopinae. On the basis of number of species, subfamily Oedipodinae was again found to be most dominant with 6 species followed by Oxyinae with 5 species, Catantopinae, Hemiacridinae, Gomphocerinae, Acridinae with 2 species each and the least dominant was Spathosterninae with only 1 species. The diversity indices for acridoid have been calculated for the first time from Terai region of Uttarakhand. Across the survey, Simpson’s diversity index (D’) & Shannon diversity index (H′) was calculated as 0.8333 & 2.195 respectively, which means that the acridoid population is moderately diverse in the surveyed area.
... The diet of the American kestrel in the study area includes an important component of reptiles, birds, and rodents, as well as orthopterans (Frixione and Rodríguez-Estrella 2020). When orthopterans, and other arthropods, become highly abundant are sprayed with pesticides to prevent damages to crops; pesticides are usually applied during the nymph and adult stages, in the late summer and early autumn (Lockwood 1993;Huerta et al. 2014). Upon being consumed by vertebrates, the agrochemicals can bioaccumulate through rodents, birds, and reptiles. ...
Raptors as top predators have been used as effective sentinels of environmental stressors in agricultural areas worldwide. Pollutants in agricultural areas have negative effects on top predator populations. Biomarkers such as erythrocyte nuclear abnormalities have been used as an effective measure of genotoxicity caused by exposure—particularly short-term exposure—to pollutants. We took blood samples from 54 wild specimens of American kestrel (Falco sparverius) captured in an agricultural area in Valle de Santo Domingo, Baja California Sur, Mexico in the autumns of 2018 and 2019 (n = 25) and the winters of 2019 and 2020 (n = 29). We prepared and examined blood smears to look for erythrocyte abnormalities as a means to evaluate genotoxicity. The number of abnormality types and the total frequency of abnormalities (MNs and NAs: notched, symmetrically or asymmetrically constricted, displaced, or indented nuclei) per 10,000 erythrocytes were calculated for all the specimens. We found a high frequency of abnormalities in numerous individuals, similar to those found in raptors from highly polluted areas. The best-fit generalized linear model for the number of abnormality types included season-of-the-year as the main significant predictor; the model for the total frequency of abnormalities included season and wing chord, an indicator of body size and health condition, as significant predictors. MNs frequencies were significantly related to season; NAs frequencies were related to season, wing chord length, and coverage of native vegetation around the area where the birds were captured. Abnormalities observed in the autumn closely coincide with the time when agrochemicals are applied in the area, mainly after the rains and during hot spells in late summer and early autumn. Small-sized kestrels showed higher frequencies of NAs, with an additional impact if native vegetation had been cleared for agriculture; this suggests both that resident birds are more exposed, and the observed genotoxicity has a local origin. These results, together with the ecological and physiological characteristics of the American kestrel suggest that this charismatic and widely distributed species might constitute a suitable biomonitor of genotoxicity in rural landscapes.
... In classical and augmentative biological control non-native BCAs are introduced intentionally, while the focus of conservation biological control is to enhance the impact of natural enemies already present in the environment. The concept of biocontrol started to gain new perspectives in the early 1980s and 1990s, not only on its efficacy but also on its safety as potential problems from non-native agents had been insufficiently considered (Howarth 1983(Howarth , 1991Lockwood 1993;Simberloff and Stiling 1996). Soon thereafter, the unintended side-effects of previous introductions were documented by a vast amount of scientific evidence (e.g. ...
In an Environmental Risk Analysis (ERA) benefits and risks of a biocontrol agent (BCA) or other beneficial organisms are assessed using criteria based on ecological determinants such as the potential and impact of establishment and dispersal, on known and new hosts (host range vs. specificity) and direct and indirect non-target effects. There is a wide variety of natural enemies used for biocontrol, each of which has its specific biological and ecological requirements. In regulatory requirements for regulation and registration of non-native agents, assessment of host specificity is one of the main criteria in evaluating risks. Establishing a generalist’s potential host range in a new area is one of the most challenging issues to be assessed prior to its introduction and release. Thus, generalist predators and parasitoids are often excluded a priori from being licensed. Here we will discuss several examples of different taxa with a generalist host range and show that each of them has specific requirements and as a result require a specific risk assessment of their own.
... Use of a selective nematicide increased natural enemy survival and reduced pest problems (see Chapter 9: Costa Rica). Human actions that protect and stimulate the performance of naturally occurring beneficial organisms Classical biological control (CBC) (Greathead, 1994) Inoculative control (van Lenteren, this chapter); Importation control (Nordlund, 1996) Introduction of relatively low numbers of beneficial organisms from the area of origin of the pest with the aim to obtain permanent control Augmentative biological control (ABC) (DeBach, 1974) Inundative control (van Lenteren, 1986) Seasonal inoculative control (van Lenteren, 1986) Mass production and periodic release of beneficial organisms without aim to obtain permanent control Periodic release of large numbers of organisms to obtain immediate control of the pest in crops with a short production cycle Periodic release of relatively low numbers of organisms to obtain control during several generations of pests in crops with a long production cycle Special cases of classical biological control: Fortuitous control (FBC) (DeBach, 1974) Control of a pest by an accidentally introduced beneficial organism Neoclassical biological control (Lockwood, 1993) New association control (Hokkanen and Pimentel, 1989) Use of exotic beneficial organisms to control a native pest ...
Biological control with arthropod natural enemies and microbial control agents has been applied since the year 1895 in Latin America and the Caribbean and is currently used on a very large scale. Sources about the history and current situation of biocontrol in this region were not easy to trace and are, therefore, presented in this chapter. Next, organizations working on biocontrol in this region are listed. This is followed by a description of natural, conservation, classical and augmentative biocontrol with some regional examples. Then, an approach to find, evaluate and use biocontrol agents is sketched, as guidance for research projects. Often, tens to a hundred biocontrol candidates are found in association with a pest. A well organized research approach using evaluation criteria allows for quick exclusion of unsuitable or problematic candidate species. Biocontrol research has limited funding and early elimination of poor candidates results in spending more money on promising candidates. Regulations concerning import and release of agents that have been implemented during the past 30 years are summarized. Effects of these regulations are that prospecting for exotic natural enemies is now very difficult and that fewer new biocontrol agents have become available. Finally, the structure of the book is explained.
... There is currently a regulation on the registration of biopesticides in which data such as the identity and composition of the microbial pesticide (scientific name, inert ingredients), physicochemical properties (colour, pH), biological properties of the agent (degree of specificity), toxicological information (oral and dermal toxicity), ecotoxicological information (effects on terrestrial and aquatic flora and fauna), and stability studies (product life) are required (COFEPRIS, 2005). Several biosafety tests have been performed on these fungi and other biological control microbial agents, concerning their toxic characteristics, as well as their environmental safety, for example, on the ecosystem stability, due to their persistence in the environment (Zimmermann, 1993), and there are questions regarding the introduction of exotic strains that must be considered (Lockwood, 1993). ...
Metarhizium is a genus of entomopathogenic fungi that was initially classified into three species and varieties. More recently, DNA sequencing has improved the phylogenetic resolution of Metarhizium which now includes 30 species. The insect host ranges vary within the genus and some species such as M. robertsii have broad host ranges, while others such as M. acridum show a narrow host range and are restricted to the order Orthoptera. Metarhizium spp. are ubiquitous naturally occurring soil inhabiting fungi, and some are rhizosphere colonisers and their diversity has been attributed to various selective factors (habitat type, climatic conditions, specific associations with plants and insect hosts). Metarhizium have been used for the biological control of insect pests that affect economically important agricultural crops and have been tested under laboratory and field conditions for the control of insect vectors of human disease, showing the effectiveness of the fungus against the target pest. In Mexico, Metarhizium species have been used for the control of insect pests such as the spittlebug (Hemiptera: Cercopidae), and locusts (Orthoptera) that affect crops such as corn, bean and sugarcane. Biosafety studies, such as dermal and intragastric tests in mammalian models have also been carried out to ensure safety to humans and other animals. Metarhizium shows great promise as an alternative to chemical insecticides that has relatively low impact on human health and the environment. Key features of Metarhizium for biocontrol of insects are outlined with special reference to their utility in Mexico.
... Environmental safety and ecosystem stability considerations lead to the conclusion that the use of native isolates in a microbial control program is more convenient (Lockwood, 1993). In Integrated Pest Management, application of right plant protection methods through right appliance may check the pest population in an effective manner. ...
In recent years, increased interest has been shown towards biological control based management practices following the unsatisfactory results with the application of conventional insecticides. In Integrated Pest Management, selection of right plant protection methods coupled with right appliance is important to tackle the target pest in an effective manner. In this context, microplot and field trials
were carried out to evaluate the efficacy of the oil based formulation of B. bassiana (Bb 112) against chilli thrips, Scirtothrips dorsalis
Hood to identify an effective delivery method among different sprayers used (ASPEE Maruyama Engine sprayer, Avenger ULV sprayer,
ASPEE Battery sprayer, ASPEE Knapsack hand sprayer, ASPEE Hitech hand sprayer and CDA sprayer). Microplot experiment on chilli
thrips, S. dorsalis revealed that the oil based formulation of B. bassiana (Bb 112) was significantly superior to all other treatments and recorded the highest cumulative mean population reduction of 47.54 per cent. The cumulative mean per cent reduction in first (at Kumarapalayam) and second field trial (at Ambilikkai) against Chilli thrips showed that, oil based formulation of B. bassiana (Bb 112) @ 108 spores ml-1 sprayed with CDA sprayer was significantly superior to other treatments with 43.01 and 46.65 per cent reduction, respectively.
... The isolation and identification of native entomopathogenic fungi are necessary to provide a pool of biological agents for pest control. Fungal species from other areas may not be effective due to environmental differences (Lockwood, 1993). Beauveria, Metarhizium, Lecanicillium are among the most common bioagents. ...
p> Simplicillium lanosoniveum isolate SSBG2 was isolated from the diseased C. hesper collected from Schefflera octophylla in greenhouse of the South-Siberian Botanical Garden, and identified based on morphological observation and ITS region analysis. The infected plants were inoculated with conidial suspension of the isolate SSBG2 in concentrations 1.0*10<sup>5</sup>/mL. It was showed that after inoculation the C. hesper female adults were more vulnerable to infection. Larvae are affected to a lesser extent. The mycelium grows under the scale and cause the death of the insect. It was indicated that S. lanosoniveum had high infectivity against C. hesper . Infection symptoms appeared on day 7 after the inoculation, the infection reached the peak on day 20. Our study provides a new isolate that affects the Coccus hesperidum .</p
... The number of host species that a biocontrol agent is capable of utilizing for its survival and reproduction determines its host specificity. Host specificity is a primary consideration for biocontrol agents before their introduction against an arthropod or weed pest, as it affects not only the efficacy in controlling the target pest populations but also whether attacks on non-targets are likely to occur in the targeted ecosystem Follett and Duan 2000;Howarth 1983;Lockwood 1993). In general, greater host specificity results in a lower probability of non-target impacts. ...
Arthropod biological control has long been used against insect, mite and weed pests in agriculture production systems, forests and other natural ecosystems. Depending on the methods of deploying natural enemies and the type of control agents (herbivores, parasitoids and/or predators), potential environmental impacts of this pest control technology in ecosystems affected by invasive species may vary. Conservation biological control, involving deployment of various methods to conserve and enhance naturally occurring native herbivores, parasitoids and/or predators, has minimal negative impacts on the environment and ecological services. In contrast, classic biological control, involving the introduction and establishment of specialized non-native natural enemies, can sometimes lead to unexpected ecological consequences in the targeted ecosystem. The risk of augmentative and inundative releases of natural enemies will depend on the host specificity of the agents involved. All types of biological control result in increased numbers of natural enemies and, in the case of classic biological control, an introduced natural enemy can potentially develop new associations with novel non-target hosts via host range expansion in its new environment. New associations can be discussed in terms of invasion biology and community ecology (e.g. top-down effects on the target pest). In this chapter, we analyse the community- and population-level processes typical of classic biological control, and assess their possible environmental impacts, particularly those associated with the planned introduction of non-native arthropod natural enemies to a new ecosystem. Risk analysis and assessment for different types of arthropod biological control are examined in the context of pest management. Two case studies (i.e. emerald ash borer and tamarisk) are presented to assess their risks and benefits relative to other pest control methods such as no action, chemical control and mechanical control.
... He developed the theory of ''new associations'', suggesting that natural enemies that have never been in contact with a host, or prey, would perform better than natural enemies with which it co-evolved. In the 1980's this theory was further developed and advocated by other authors (Carl 1982;Pimentel 1984, 1989) and the approach of controlling native species by the introduction of exotic natural enemies was later named ''neo-classical biological control'' (NCBC) (Lockwood 1993). Consequently, there were several NCBC projects during the 1980s and 1990s. ...
Classical biological control (CBC) is the introduction of a natural enemy of exotic origin to control a pest, usually also exotic, aiming at permanent control of the pest. CBC has been carried out widely over a variety of target organisms, but most commonly against insects, using parasitoids and predators and, occasionally, pathogens. Until 2010, 6158 introductions of parasitoids and predators were made against 588 insect pests, leading to the control of 172 pests. About 55% of these introductions were made against pests of woody plants. Establishment rates of natural enemies and success rates were higher in CBC projects targeting pests of woody plants than other pests. This review aims to answer the questions most commonly asked regarding CBC against insect pests, with particular emphasis on tree pests. The topics covered include, among others: variations in rates of successes among different systems, different target insect groups and different agents; temporal trends in CBC practices and successes; economic and environmental benefits; risks and ways to mitigate the risks; CBC against native pests; accidental successes through the adoption of the invasive pests by native natural enemies or accidentally introduced agents; and prospects and constraints for the practice of CBC in the future. Questions are answered based on the analysis of two databases, the BIOCAT2010 database of introductions of insect biological control agents for the CBC of insect pests, and a database of introductions of entomopathogens against insect pests.
... Though the influence of biological control agents on rare nontarget organisms, as stipulated in the new FAQ guidelines (FAQ, 1996), was not specifically tested in this project at the time of introduction, the introduced organisms would probably fulfill the modern safety requirements. The outcome of the worldwide controversy between biological control practitioners and wildlife conservationists (see e.g., Lockwood, 1993;Carruthers and Onsager, 1993) could determine the way that biological control is implemented in the future. It behooves us, however, to remember that both sides have similar goals, namely to balance the preservation and exploitation of natural resources, of which biodiversity might in fact be the most important, for the sake of future generations. ...
... 12. The expression neoclassical biological control was coined by Lockwood (1993Lockwood ( , 1996 to explain a subset of the controversial kind of biological control advocated as "new associations" by Hokkanen and Pimentel (1984). There is controversy for two reasons. ...
... The standard answer follows the theme that the cane-toad story (one could substitute here rat snake, Indian mongoose, predatory snail, myxoma virus) has little or no scientific basis and that all these so-called 'biocontrol agents' are polyphagous opportunists that may well have huge and permanent impacts on vulnerable ecosystems. In the case of the myxoma virus, in what has been termed neoclassical biological control (Lockwood, 1993;Simberloff and Stiling, 1996b), or the new encounter hypothesis (Hokkanen and Pimentel, 1984), it is even more bizarre because the pathogen that was targeted at a European rabbit in Australia came from a South American fox! Sadly, the long-term benefits from such new-encounter introductions are negligible, or even negative, because after the initial epidemics, resistant hosts will bounce back, with the non-specialist pathogen being unable to respond. ...
... Classical biological control has long been used for sustainable management of exotic arthropod pests in agricultural and forest ecosystems (e.g., in van den Bosch et al., 1982;Van Driesche et al., 2010). Because this pest control approach involves the introduction and establishment of non-native species of predators or parasitoids, potential risks of the candidate agents to non-target organisms in the receiving ecosystem need to be thoroughly assessed prior to environmental release (Howarth, 1983;Lockwood, 1983;Follett and Duan, 2000). Host range determination or host specificity testing for candidate predators or parasitoids prior to their environmental release has become a critical step in modern classical biological control programs, providing data necessary for assessing the non-target risk of proposed biological control introductions (Follett and Duan, 2000;Van Lenteren and Loomans, 2006). ...
... Further the method of broadcasting the fungus along with the culture substrate is also feasible for promoting its further multiplication in the field, generating the high spore inoculum required for controlling the major leaf eating lepidopteran pests of economically important crops. Environmental safety and ecosystem stability considerations lead to the conclusion that the use of native isolates in a microbial control program is more convenient (Lockwood 1993). The practice of developing indigenous fungal strain is preferable for development of mycopesticide formulation for application against local pests in view of better ability to adapt to the local conditions. ...
Conidiospores of the entomopathogenic fungus Metarhizium anisopliae were produced by solid state fermentation
using sorghum/barley/rice grains. Shelf life and viability of oil formulatations as well as unformulated infective propagules
was tested by germination bioassay and pathogenicity studies on Spodoptera litura larvae. Viability of unformulated
conidiospores stored at three temperatures (4°C, -30°C and room temperature) was understood using germination bioassay.
Studies on seven oil formulations and two powdered formulations for shelf life at 4°C, revealed 60% viability of
conidiospores formulation with gingelly oil, stored for six months. Virulence of the infective propagules studied against
third instar Spodoptera litura larvae during six months storage demonstrated insect mortality ranging from 40 to 88.33% with
LT50 values of 4.63 to 13.07 days. Field application of infective propagules on Vigna sinensis crop heavily infested with S.
litura suggested insect mortality ranging from 51.35% to 88.65% at 1X1012 conidia/ ml of gingelly oil formulation.
... Exotic strains of entomopathogenic fungi that have been developed for use as pest control agents in different countries may be ineffective due to strain and environmental differences (Lockwood, 1993;Bidochka et al., 1998). Therefore, investigating the occurrence and distribution of native entomopathogenic fungi is critical for their use as pest control agents in a given location. ...
The green peach aphid, Myzus persicae Sulzer, is an important pest that infests more than 40 families of plant and has become a serious problem due to its high resistance to insecticides. To address this problem, interest in entomopathogenic fungi as biocontrol agents in the context of integrated pest management strategies has increased. In this study, we report the efficient screening of entomopathogenic fungi for control of the green peach aphid through the evaluation of environmental factors as well as virulence. Initial screening based on pathogenicity against the green peach aphid was performed using 342 isolates of entomopathogenic fungi from Korea. Twenty different entomopathogenic fungi were isolated from green peach aphid cadavers supporting fungal conidiation. These isolates were identified by microscopic examination, genetic sequencing of the ITS region, and universally primed PCR (UP-PCR) as follows: 3 isolates of Lecanicillium attenuatum, 9 isolates of Beauveria bassiana, 1 isolate of Metarhizium anisopliae, 1 isolate of Metarhizium flavoviride, 5 isolates of Purpureocillium lilacinum, and 1 isolate of Aspergillus sp. Further virulence and environmental factors such as thermotolerance, UV-B tolerance, and cold activity were evaluated simultaneously to select 20 isolates because the importance of environmental factors in the development of bioinsecticides is greatly increasing. Virulence and environmental factor activities varied based on the fungal isolate. Purpureocillium lilacinum SD17 was selected as the most likely candidate for a biocontrol agent against the green peach aphid based on a relative comparison of its activities, including virulence. © 2015 Korean Society of Applied Entomology, Taiwan Entomological Society and Malaysian Plant Protection Society.
The natural occurrence of entomopathogenic fungi (EPF) was investigated along the Ticino River (Ticino River Natural Park, Novara Province, Piedmont, Italy), at the center of the area of the first settlement of the invasive alien pest Popillia japonica. Using Zimmermann's "Galleria bait method", EPF were successfully isolated from 83 out of 155 soil samples from different habitats (perennial, cultivated, or uncultivated meadows, woodlands, and riverbanks). Sequencing of the 5' end of the Translation Elongation Factor 1 alfa (5'-TEF) region allowed the assignment of 94% of the isolates to Metarhizium spp., while 8% and 7% were assigned to Beauveria spp. and Paecilomyces spp., respectively. Four Metarhizium species were identified: Metarhizium robertsii was the most common one (61.5% of the isolates), followed by M. brunneum (24.4%), M. lepidiotae (9%), and M. guizhouense (5.1%). Microsatellite marker analysis of the Metarhizium isolates revealed the presence of 27 different genotypes, i.e., 10 genotypes among M. robertsii, 8 among M. brunneum, 5 among M. lepidiotae, and 4 among M. guizhouense. Metarhizium brunneum appeared to be associated with woodlands and more acid soils, while the other species showed no clear association with a particular habitat. Laboratory virulence tests against P. japonica 3rd instar larvae allowed the identification of one M. robertsii isolate that showed efficacy as high as 80.3%. The importance of this kind of study in the frame of eco-friendly microbiological control is discussed.
Plagues caused by locusts and grasshoppers have led to severe crop damage and great economic loss in many countries. Nevertheless, populations of these pests are often suppressed by naturally occurring predators and disease. Among such natural control factors, the entomopathogenic fungus, Entomophaga grylli, can markedly disrupt the dynamics of grasshopper populations. However, there are few reports of epizootics of this entomopathogenic fungus occurring in consecutive years. Here we report on a consecutive 2-year field survey of E. grylli epizootics in Xinjiang, Northwest China. E. grylli were observed to infect at least four species of grasshopper, Calliptamus italicus, Gomphocerus sibiricus, Chorthippus sp., and Stauroderus scalaris. This is the first record of infection of the last two species by this pathogen. The highest infection rates at the two study sites (Chonghuer and Jiadengyu, Altay Prefecture) were ≥50%, observed in mid-July 2011, and the lowest rate was >16% in early summer. The density of infected grasshoppers was positively correlated with the density of total grasshoppers collected (r = 0.981). Therefore, E. grylli is an important natural factor regulating the dynamics of grasshopper populations in regions that are not subjected to artificial treatments.
Ontsira mellipes Ashmead (Hymenoptera: Braconidae) is a North American parasitoid species that develops on the invasive pest, Anoplophora glabripennis (Moltschulsky) (Coleoptera: Cerambycidae), under laboratory conditions and is currently being considered as a potential new-association biocontrol agent. To develop mass-rearing protocols and field-release strategies for this parasitoid, information on its reproductive biology in relation to temperature is needed. We determined the effect of temperature (10, 15, 20, 25, and 30 C) on development , survivorship, and sex ratio, and its effect on the longevity, fecundity, and host attack rates (parasitism) of adults. Developmental time for parasitoid eggs to pupae decreased from 26.7 d to 6.1 d as temperature increased from 10 C to 30 C. While no pupae eclosed as adults at 10 C, time of adult emergence from pupae decreased from 39.7 d to 12.2 d as temperature increased from 15 C to 30 C. Based on estimated lower development temperature threshold (11.1 C), the degree-days required for one generation was estimated at 342.9. When female parasitoids were provided with host larvae, parasitism occurred at all temperatures and was maximized at 25 C. Additionally, increasing temperatures significantly reduced the preoviposition period and lon-gevity of female O. mellipes. In addition, combining these results with temperature data from areas in the United States currently infested with A. glabripennis, we estimated that O. mellipes can complete 1.2–3.7 generations per year. Findings from this study may be considered for the future development of effective mass rearing and augmentative release strategies of O. mellipes for biological control of A. glabripennis.
The vast numbers of alien arthropods across the world collectively impose major conservation concerns. Many insect invaders are presumed to be pests but, even for acknowledged pest species, debates can become divisive both in (1) assessing severity of impacts beyond an immediate pest context and (2) the remedial actions needed. The Australian Light brown apple moth (Epiphyas postvittana, Tortricidae) in California, where it was recorded first in 2007, is highly polyphagous with its larvae reported to feed on more than 200 plant species, including many crops. This discovery led to a massive eradication campaign. However, as discussed by Chen (2010), some entomologists doubt that it is really a recent invader but may have been in California for several decades over which it did not come to notice through any significant damage to crops. In that case, a highly expensive eradication campaign would not be needed, and is highly unlikely to succeed. E. postvittana, as a well-known and economically significant insect, simply indicates the problems that arise in seeking sound information on impacts and any remedial steps in a new, or previously undetected, environment where, essentially, the history and reality of invasion is unknown. Pest management, to a large extent founded on invasive insects of economic, social or ecological importance, continues to provide examples of the diverse impacts of invasive taxa, and parallels with conservation management – albeit often from different ‘directions’ of suppression or encouragement.
This chapter inspires political change that will enable society to harness the power embedded in biological control to benefit species and ecosystems under threat from introduced plants and insects. Biological control is a collaborative effort involving local, regional, and international partners. The chapter uses Public Trust Thinking (PTT) principles to offer a critique of the status quo in invasive species management and biological control and then propose fundamental biological control principles as a guide to the future. Principles of PTT are helpful in strategically contemplating roles and responsibilities of land managers, scientists, citizens, and voters. The chapter reviews responsibilities of land managers and land management agencies, biological control scientists, regulatory agencies and reviewers, politicians, and the public at large. It explores both the fundamental grounding of biological control in environmental stewardship and responsibilities of people and agencies as partners in biological control program development and implementation.
Adding a natural enemy for the control of an invasive species introduces a new pathway into an existing ecosystem in which the pest is already well established. The issue of interest following the establishment of the natural enemy in this new system is learning how strong the connection to the target is and whether the biological control agent develops ecologically significant, quantifiable non-trophic or trophic linkages to other organisms in this environment. Understanding these food or interaction web effects helps to understand how the natural enemy interacts within its new ecosystem, where it has not existed previously, but where the target may have long been established. This chapter examines both non-trophic and trophic effects that deliberately introduced natural enemies have had following their introduction for the control of an invasive pest. It also focuses on predicting unwanted trophic effects of carnivorous biological control agents and pathogens.
The introduction of an organism to a new ecosystem has the potential to be simultaneously an ecologically and ethically consequential act. The release of a novel biological control agent into wildlands is a special category of introduction that should be justified by social values and conservation goals. This chapter explains that why the introduction of a biological control agent is necessarily ethical in character. It describes how environmental ethics evolved to encompass biological control as an ethical issue, and analyzes decision-making processes that are based on consideration of risk. The chapter proposes an ethical frame-work for more effectively integrating ethics in biological control decision-making. The field of ethics can help fashion a more responsive and democratic decision-making model to integrate biological control into conservation practice. Public engagement requires careful attention to devising appropriate roles for stakeholders, and opportunities for public input in decision-making processes.
The mission of APHIS and its predecessor agencies within the USDA is consistent with a key goal of conservation biology: preventing the introduction of harmful nonindigenous organisms. Realizing this goal requires informed decisions by regulatory risk managers regarding importations of agricultural commodities. The technical basis for these informed decisions is most often a plant pest risk assessment. Past plant pest risk assessments and, indeed, the majority of current assessments have used qualitative measures of the risk posed by commodity pathways. Increasingly, probabilistic assessments have emerged as the risk assessment method of choice to support difficult regulatory decisions. The United States has taken the lead in using this type of assessment for agricultural trade. But assessments of this type are becoming more common, and New Zealand, Australia, and Canada have conducted risk assessments of this type in support of decisions on international trade in agricultural commodities. Biological systems in general and plant pest-commodity interactions in particular are difficult to assess both because of their inherent complexity and the frequent dearth of data available to describe them. Probabilistic assessments provide the best available tools to account for the variability and uncertainty that biological complexity and data gaps introduce into the plant pest risk assessment process.
The vast majority of the world’s species are insects (at least 80%; Mawdsley and Stork 1995). Their importance is overwhelming by almost any measure. For example, insects and other arthropods contribute substantially to standing biomass; 1,000 kg/ha is an estimate for the United States (Pimentel et al. 1980). In most terrestrial and freshwater ecosystems they play critical roles as prey, predators, herbivores and pollinators (Free 1970; Debach and Rosen 1991; Kellert 1993; Lloyd and Barrett 1996). Indeed, in one of the first issues of the Society for Conservation Biology’s journal, E.O. Wilson (1987) called insects “the little things that run the world.” Because they comprise the majority of the earth’s biodiversity, insects should be considered pivotal in conservation efforts (Kim 1993). Unfortunately, an alarmingly small percent of our conservation literature focusses on insect issues. For example, in 1993, 1994 and 1995, the journals Ecological Applications, Conservation Biology, and Biological Conservation published 1,070 articles with only 62 related to insect issues and still fewer related to conservation of declining insect populations. Thus, only 6% of our conservation literature is aimed at 80% of our planet’s biodiversity. This neglect of insect conservation cannot be justified on the basis of insects not being endangered. In Britain where the biodiversity is relatively well-documented, approximately 22,500 insect species occur; 43 insects are believed to have gone extinct between 1900 and 1987 (Hambler and Speight 1996). The number of insect species believed extinct in Britain is over eight times that of number of extinct vertebrates, and over three times that of flowering plants (Hambler and Speight 1996).
In this final chapter we shall focus on those insects that humans describe, in their economically minded way, as beneficial or harmful, though it should be appreciated from the outset that these constitute only a very small fraction of the total number of species. Further, it must also be realized that the ecological principles that govern the interactions between insects and humans are no different from those between insects and any other living species, even though humans with their modern technology can modify considerably the nature of these interactions.
Microsporidia are obligately parasitic single-celled spore-formers of uncertain taxonomic affinity. Considered protozoans until several recent genetic analyses showed them to be aligned with the fungi (Keeling & Doolittle 1996; Germot et al. 1997; Hirt et al. 1999; Keeling et al. 2000; Bouzat et al. 2000), they are nevertheless a unique group of organisms that interact with their hosts in a variety of ways. Nearly 1,000 species of microsporidia have been described, and most of these, approximately 700 species, have been isolated from insects (Becnel & Andreadis 1999). Since most studies of microsporidia focus on hosts that are of agricultural and medical importance, probably only a small fraction of existing species have been described. Records of population suppression by microsporidia of insect species such as Euproctis chrysorrhoea (L.) (Sterling & Speight 1989), Choristoneura fumiferanae (Clemens) (Wilson 1973), Ostrinia nubilalis Hübner (Andreadis 1984; Siegel et al. 1987; 1988) the trichopteran Glossosoma nigrior Banks (Kohler & Wiley 1992; 1997) and others, indicate that this group of pathogens are significant natural enemies of many insect species.
Classical biological control of invasive species of arthropods is a well established discipline that has a long and distinguished record (DeBach, 1964; Huffaker and Messenger, 1976; Clausen 1978; Van Driesche and Bellows, 1996; Bellows and Fisher, 1999). Laws governing the conduct of classical biological control vary by country, or may not exist at all. An international code of conduct for the practice of natural enemy introductions has been developed by the Food and Agriculture Organization of the United Nations and can be consulted for an overview of good practice (Anon., 1997).
Grasshoppers are serious pests of crops worldwide. In the present era of changing agricultural practices and uncertainty regarding the impacts of global climate change, the need to understand the nutritional ecology of grasshoppers is urgent. In the present study newly hatched nymphs of two multivoltine acridids, Spathosternum prasiniferum prasiniferum and Oedaleus abruptus, were fed with four food plants of the family Poaceae: Cynodon dactylon, Triticum aestivum, Sorghum halepense and Oryza sativa. Then their growth, adult life span, food consumption and utilisation were recorded. Sorghum halepense was found to be the most suitable food plant for S. pr. prasiniferum whereas for O. abruptus it was Triticum aestivum followed by Sorghum halepense in most cases. The results from the present study may help forecasting modellers to simulate a predictive model that may speculate future outbreaks, forage loss and its possible effects on the economy more efficiently.
After a spring flood in the river Elbe region in 2006, grasshoppers in floodplain meadows of the Biosphere Reserve 'Flusslandschaft Mittlere Elbe' were checked for the occurrence of parasitoids. Five species of the local grasshopper faunations (15 species) were affected by parasitoids: Chorthippus parallels, C. biguttulus, C. dorsatus, C. albomarginatus and Stethophyma grossum. Parasitoids from the taxa Mermis (Nemathelminthes), Blaesoxipha (Diptera, Sarcophagidae) and larvae of a Tachinidae (Diptera) species played a role in grasshopper parasitation. Mermis depends on a high degree of soil moisture, even in the egg-laying period. Blaesoxipha, however, showed no relation to the flood and was also found in the control meadow. Blaesoxipha can fly in its adult stage and is widespread in the region. All grasshoppers infected by Mermis were sterile, with the exception of a single C. parallelus female with a (low) number of eggs in the ovaries. In contrast, grasshoppers infected by Blaesoxipha showed a rather normal fertility. In C. biguttulus (two cases) we found more than a single parasitoid. The parasitoid generation cycle is discussed.
This chapter discusses microsporidian pathogens that have been studied extensively relative to their potential or utilization as biological control agents of rangeland grasshoppers, the European corn borer (ECB), mosquitoes, red imported fire ants, and gypsy moth. Aspects of the microsporidium's pest suppression characteristics are highlighted within the context of the host's ecology. The chapter lists detailed reviews of the microsporidian pathogens of each of these pests. It presents a summary of microsporidia in field-collected and mass-reared beneficial insects used for biological pest control as well as infections in beneficial insects that control pest insect populations in nature. The observation that microsporidia tend to have more noticeable effects when host insects are under stress is likely the reason why they are observed often in laboratory and commercial mass-rearings.
We experimentally studied the effects of avian predation on grasshopper abundance in western North Dakota during the summers of 1988 and 1989. Grasshopper densities in 15 x 15 m plots from which birds were excluded (NO BIRDS) were compared with similar-sized plots where birds were allowed to forage (BIRDS). Plots were established in early June at 16 sites (8 per year), and grasshopper densities were estimated from hoop counts in NO BIRDS and BIRDS plots at 2-wk intervals until the end of July. There were significantly more grasshoppers in NO BIRDS plots than in BIRDS plots in 1989 (P < .0001), but not in 1988 (P = .137). The difference between treatments in 1989 was first detected 6 wk after the exclosures were erected. Between years there were no differences in initial grasshopper abundance in all treatments (P > .388). After the final hoop count each year, sweep-net sampling was also used to estimate grasshopper densities. By this method, average grasshopper density in late July was 26% and 37% lower in BIRDS plots than in NO BIRDS plots in 1988 and 1989, respectively. Average length, total biomass of grasshoppers, species richness, and species diversity, however, did not differ between the treatments. In 1988, 2 of 15 grasshopper species were significantly more abundant in the NO BIRDS plots. There was no difference between the treatments among 16 species identified in the 1989 samples, but the power of our tests to detect differences for individual species was low. Our results support the hypothesis that avian predation reduces insect populations at low and moderate densities.
The success of introducing natural enemies for biological control was found to be about 75% higher employing new parasite–host (predator–prey) associations than those based on long-evolved associations between parasites and hosts. The lack of evolved interspecific balance in new species associations appears to explain the higher success rate. New exploiter–victim associations expand opportunities for the biological control of both introduced and native pests and should be used as the preferred method in selecting biological control agents.
Even in a world of continua there are discrete entities. Entomologists, frequently faced with applied problems, require an understanding of ecological patterns. In pest management, entomologists often find that past research is fragmented and a clear picture of the complexity of the system in question is difficult to construct. Recent work on rangeland patch dynamics indicates that grasshopper community complexity is related to specific vegetation types. In this article, we discuss the potential application of the concept of discrete typal vegetation communities to insect ecology and pest management. We argue that approaches of this type win be useful in the management of heterogeneous natural resource systems such as rangelands and forests and will support the recursive interaction between basic and applied research in insect ecology.
Interspecific associations of rangeland grasshoppers studied in Gallatin Valley, Mont., during 1988-1990 when regional densities were low, showed a great deal of spatial variation. Although ≥40 rangeland grasshopper species were collected valley-wide throughout this study, mean species richness at the habitat type level ranged from ≍10-17; results suggest that species replacement occurred over the gradient of habitat types sampled. Based on the results of this and previous research, it appears that rangeland grasshopper communities consist of facultative assemblages of species. At the valley level, it was possible to distinguish between species groups in temlS of their general distribution characteristics (i.e., broadly, intermediately, or narrowly distributed). Although there appeared to be a maintenance in the proportion of the species in each of the three distribution groups among the six habitat types studied, proportions differed from those found at the valley level. Similar to other studies in plant and insect ecology, a positive relationship between species abundance and the number of sites collected was found at both the habitat type and valley levels. Because of the differences found in species composition at the habitat type level, the generalization of detailed experimental studies, beyond the habitat type level, must be done with caution. Lastly, it is clear that to understand rangeland grasshopper communities in general, large-scale observational studies designed to depict pattern must be conducted together with small-scale studies designed to elucidate process.
Diets of grasshopper species from two arid grassland communities in Trans-Pecos, Texas, were determined by gut analysis. Species-specific food plant choice and niche breadths are presented for each of these species. As a group, grasshoppers range from monophagous to polyphagous feeders although most species fall in the oligophagous to polyphagous group. Phylogenetic constraints are evident such that gomphocerinae are primarily grass feeders while melanoplinae feed predominantly on forbs; the oedipodinae show less clearcut tendencies.
Feeding patterns are remarkably constant from site to site and overall, community niche breadth distributions between sites do not differ greatly. Individual species tend to eat the same plant species at various sites and maintain similar niche breadths. Species with relatively specialized diets tend to feed on predictable plant species such as grasses and long-lived perrenial forbs.
Grasshopper feeding patterns present some problems to the current theory of herbivore diet specialization since forb feeding melanoplines tend to be polyphagous (contrary to predictions). Life history patterns unrelated to tracking host plants may explain some aspects of diet breadth since diet selectivities are presumably adjusted according to the probability of finding suitable food plants.
"An important, controversial account ... of the way in which man's use of poisons to control insect pests and unwanted vegetation is changing the balance of nature." Booklist.
Introduced insects attract public attention primarily when they become “pests.” The impact of fire ants, killer bees, gypsy moths, Japanese beetles, and Colorado potato beetles on our economy and environment is well known. The last have even played roles in international politics. The Ministry of Agriculture under the Third Reich generated antagonism against the British before the start of World War II with the rumor that English planes had dropped larvae of the beetle on areas where the German farmers had massive stores of potatoes. And, during one of the most frigid moments of the Cold War, the Soviet Union claimed that the United States had bombed eastern Europe with the Colorado potato beetle, which the Russian press called “the six-legged ambassador of Wall Street” (Kahn 1984).
Foraging behavior of Hesperotettix viridis was studied in a New Mexico grassland where it fed almost exclusively on the shrub Gutierrezia microcephala (Compositae). During its annual 4-mo feeding period, H. viridis progressively reduced the quality and quantity of edible host plant tissues. By midsummer, when most grasshoppers reached maturity, plants attacked by grasshoppers had significantly lower shoot water content, N content and edible biomass per stem than plants experimentally protected from feeding damage. Grasshoppers fed in short bouts and sampled different plants continuously; most animals found on a plant abandoned it within a day. The tenure of grasshoppers on plants tended to be shorter for plants growing in dense stands. Tenure was not affected by current grasshopper density on a plant, but did vary with a plant's history of feeding damage. Animals confined for 7 d on high- vs. low- quality plants differed in their subsequent foraging behavior, suggesting that grasshoppers use information related to their recent feeding history to assess the quality of particular plants. -from Author
African pastoral ecosystems have been studied with the assumptions that these ecosystems are potentially stable (equilibrial) systems which become destabilized by overstocking and overgrazing. Development policy in these regions has focused on internal alterations of system structure, with the goals of restoring equilibrium and increasing productivity. Nine years of ecosystem-level research in northern Kenya presents a view of pastoral ecosystems that are non-equilibrial but persistent, with system dynamics affected more by abiotic than biotic controls. Development practices that fail to recognize these dynamics may result in increased deprivation and failure. Pastoral ecosystems may be better supported by development policies that build on and facilitate the traditional pastoral strategies rather than constrain them.
(1) Population dynamics of grasshoppers living on creosote bush are examined. Several species are non-territorial and reach very high densities, and density in these species may be more strongly influenced by density-independent factors. (2) Male density levels in Ligurotettix coquilletti appear to be influenced by density-dependent territorial interactions. (3) Bushes in a 90X45 m grid were mapped, and all males were individually marked. Mid-season densities remained constant at c. 32 males over two summers, in spite of considerable male turnover. (4) The number of males in the population was increased artificially by introduction of males from the outside, but the number returned to previous levels within a few days. (5) Maintenance of territories is achieved through fighting, and repulsion of males is achieved through continuous loud stridulation. (6) Males prefer certain bush sizes, evidently the size which is likely to harbour females. Within this class of bushes males may prefer bushes sufficiently small to be defensible. (7) Males are more sedentary than females and, in our study, individuals remained on bushes for up to 39 days. (8) We suggest that territoriality in Ligurotettix evolved to increase the female quota and that food and oviposition sites would only be limiting at much higher densities. The primary cause of low male densities may be the strong competition among males for females.
The periodical ravages of locusts and grasshoppers have been sufficiently documented through history that it is easy to appreciate the seriousness of such outbreaks. We believe, however, that most people grossly underestimate the forage resources that are destroyed annually by typical "noneconomical" populations of grasshoppers. The western range comprises about 262 million ha, most of which is suitable habitat for grasshoppers. The grasshoppers annually destroy at least 21-23% of available range vegetation. That would represent a loss of about $393 million/year if that vegetation could otherwise be utilized by livestock. Current control measures are not economical on about 80 million ha because treatment cost far exceeds the value of forage that is produced. Most control programs are likely to be executed on about 160 million ha that produce forage worth about $2.50 - $7.50/ha. Significant forage destruction begins during the 3rd nymphal instar. This occurs just before maturation of many important species of grass. Thus, grasshoppers do not generally inhibit forage production; rather, they hasten decomposition of the standing crop of forage. When control measures become necessary, they should be initiated as soon as possible after the majority of grasshoppers become 3rd instars. Later treatments cannot recover forage that has already been destroyed; they simply prevent further destruction.
A stocking-rate guide for cattle on blue-grama range was developed at Central Plains Experimental Range. The guide is based on the amount of herbage left ungrazed at the end of the summer season as it relates to gain per animal and gain per acre. Maximum dollar returns per acre from yearlings were obtained when 300 lb of air-dry herbage were left at the end of the season. The average optimum stocking rate was 2.6 acres/yearling month.
Densities of the grasshopper Phoetaliotes nerbrascensis (Acrididae) were manipulated in native tall grass prairie at Konza Prairie, Kansas, to measure competitive and facilitative effects on densities of co-occuring phytophagous insects. In late June 1987, P. nebrascensis nymphs were transferred among enclosed plots (each 550-900 m^2) to produce three pairs of plots with grasshoppers either removed or added. Pretransfer densities in the six plots were estimated at @?5 nymphs/m^2, 2-2.5 nymphs/m^2 were then removed or added. Densities of the manipulated species and other abundant phytophagous insects were subsequently monitored (by sweep net) through mid-August. The manipulations in late June resulted in mean densities of P. nebrascensis nymphs 1.5--4 times as large on addition plots as on removal plots; these differences persisted through mid-August. No significant differences between treatments were found, however, in the numbers of individuals of other Acrididae or Tettigoniidae on four post-transfer sampling dates (July to mid-August). Significant differences were also not found in the numbers of individuals of Phasmatidae, Homoptera, or phytophagous Hemiptera and Coleoptera, or in the biomasses of live grass, dead grass, or forbs present in mid-August. 1987 was year of moderate primary production on Konza Prairie. The manipulations produced experimental treatments that mimicked intermediate vs. relatively high natural densities of P. nebrascensis. The results indicate that under these conditions, changes in P. nebrascensis density have little net short-term impact, competitive or otherwise, on the population dynamics of co-occurring grasshoppers or other phytophagous insects.
The average longevity of adult females of three species of Blaesoxipha grasshopper parasites was estimated at 3.0 to 4.8 days under field conditions. CircumstantIal evidence suggested predation as a major cause of mortality. When parasites and grasshoppers were isolated in large cages, average survival of parasites increased about fourfold and the level of parasitism among grasshoppers increased about fivefold over field levels. In identical cage tests that included robber fly predators, all parasites were destroyed, parasitism essentially was eliminated, and the survival rate of grasshoppers increased.
Considerable evidence substantiates the idea that native pests can be controlled by parasites and predators of allied species and genera. In a survey of 66 pest species, which were successfully controlled by biological means and for which the habitats of all species could be verified, it was found that 39% were controlled by an introduced parasite or predator of an allied species or genus. Although relatively few attempts have been made to control native and imported pests with parasites and predators of species allied to the pest species, the proportion of successes is surprisingly high. Employing these species has certain advantages, especially in the control of imported pests, because no ecological homeostasis has evolved and the association between the parasite and host (predator and prey included) is new.
Most classical biological control attempts worldwide against pet insects have failed to meet the objective of solving the pest problems permanently. The dominant cause was failure by introduced agents to colonize. Most failures to colonize can be attributed to procedures that were detrimental to the numbers or health or the target-finding or field survival abilities of newly released agents. Administrative reactions to the low success rate, poor cost/benefit data, and overselling of the method were basically responsible for those procedures. As ways of avoiding such procedures exist, it is feasible to make colonization a probability. This should substantially improve the chances of control being successful, enable past failures to be reopened, and expand the scope of classical biological control.-Author
Grasshopper (Orthoptera: Acrididae) density and species composition were monitored in three southwestern Montana grazing areas. Periodic comparisons were made of percent cover, percent crude protein, percent water content, and total phenolics for grasses grazed by cattle versus grasses protected from grazing. Grasshopper densities and composition differed in three areas. Grazing reduced vegetative cover, accompanied by increases in ground litter and patches of bare ground. Plant nitrogen and water content decreased during the spring and then increased in late summer following rains. Phenolics levels were independent of grazing and weather fluctuations. Changes in grasshopper nymph densities roughly corresponded to springtime decreases of crude protein and water content in grasses. Nymphal mortality was inversely related to density. Grazing, weather, or changes in plant chemistry had little effect on grasshopper parameters of this study.
The impact of grasshoppers on rangeland forage production, especially during years of high population levels, has been well documented by previous authors (Pfadt 1949, Nerney 1960, Putnam 1962). Most of this work, however, has concerned itself with measuring reductions in yield of various herbage species and/or grassland communities. With the recent surge of the concept of the ecosystem and its resultant impact upon ecological research (Watt 1966, Van Dyne 1969), it has become increasingly essential for research workers to adopt more holocoenotic approaches to the analyses of these relationships. Such is especially the case if the role of insects in ecosystem function is to be investigated.
This study has taken unpublished data and examined them in the context of determining what is the most “important” ecological effect that grasshoppers have on the structure and function of a shortgrass prairie eco-system
A study of the association between Melanoplus occidentalis (Thomas) and the prickly pear cactus, Opuntia polyacantha Haw., was conducted on native rangeland in southeastern Wyoming. During the study, the grasshopper population density was 14.5 ± 3.7 m-2, of which 52% were M. occidentalis in cactus patches and 16%were M. occidentalis in the surrounding rangeland. Surveys of prickly pear flowers showed that 54% of the flowers had one or more (up to four) grasshoppers, of which 96% were M. occidentalis. Females of this species comprised 72% of the individuals within the cactus patches and 33% of the individuals captured in surrounding rangeland. Of the insects found in prickly pear flowers, grasshoppers accounted for 87%of the biomass; meloids (ll %)and nitidulids (2%)made up the balance. Crop content analysis of the 10 dominant grasshopper species collected from cactus patches revealed that only M. occidentalis had fed on prickly pear flowers. Within this species, 37% of all individuals had detectable levels of prickly pear cactus tissue in their crops, including 41%of the adults (58% of the females and 28% of the males) and 23% of the nymphs. Behavioral observations revealed that M. occidentalis fed on prickly pear stamens in short (10-15 min) bouts, which were frequently interrupted by aggressive physical interactions between individuals. Evaluation of the cactus stamens of flowers in the area revealed that 20% were completely or heavily damaged, 75% were moderately to slightly damaged, and 5% were undamaged by grasshopper feeding.
This paper supplements an earlier (1952) report on parasitization of Metalor pardalinus (Sauss.) by Trichopsidea clausa (O.S.) in Montana, but deals chiefly with the effect of Neorhynchocephalus sackenii on a host population of Melanophis bilituratus (Walk.) in eastern Oregon in 1955-56. On a 200,000-acre area, a 99% reduction of an outbreak of bilituratus coincided with heavy parasitization by N. sackenii, when 70% of the hosts taken in net collections were found parasitized. Decline of the host population resulted from shortened life span and reduced egg production by parasitized individuals. In cage tests, parasitized M. bilituratus, M. bivittatus (Say), and M. femur-rubrum (DeG.) lived not more than half as long as unparasitized individuals, and their egg production was reduced by 93%, 49%, and 95%, respectively. Though M. bivittatus was found heavily parasitized in the field, apparently it is not a true host of N. sackenii as none of the fly larvae reached maturity in 180 specimens kept under observation. Parasitization of M. femur-rubrum was accomplished under laboratory conditions, by placing a sackenii larva on the abdomen of each host and watching it until penetration was complete.
Catastrophe Theory is a branch of mathematics that provides a framework for studying discontinuous phenomena. Application of the cusp catastrophe, a model with two driving or control variables, indicates that rangeland grasshopper population dynamics are catastrophic. Based on bimonthly temperature and precipitation, the cusp catastrophe modeled changes in grasshopper populations dynamics in four ecotopographic regions of Wyoming with an accuracy significantly better than chance. Although there were differences in model performance among regions, the best predictions generally occurred when the changes were large-scale outbreaks (30–45% of the total area of a region) of economic densities (≥9.6 grasshoppers/m2). Because winter weather, particularly in climatically extreme years, is correlated with spring weather, it appears that the climate in December–January has predictive value with regard to population dynamics in the following spring. However, when temperature and precipitation during hatching and early development of grasshoppers (April–May) are used as the control variables, the cusp catastrophe most accurately models the observed population dynamics.
Part 1 Theory: perspectives of biological invasions examples of invasions measures of areal expansion poopulation growth diffusion. Part 2 Applications and interpretation: parameter estimation and ecological boundry conditions simulating biological invasions birds invading Europe and America the stochastic structure of the wave front of rabies in Central Europe interpreting biological invasions.
Using the concept of the niche (and multiple niche) this book attempts to synthesise two widely-investigated topics: polymorphism and between-species competition; the author's view being that multiple-niche coexistence and multiple- niche polymorphism together represent a common means of coexistence of competitors. Experimental detail and fieldwork are frequently cited in order to create a common point of reference for both population ecologists and geneticists. Concluding chapters discuss other important principles and hypotheses in evolution which are related to the niche concept.
On North American rangelands lower successional stable states occur in sagebrush and other shrub-dominated vegetation types in the Great Basin, the short-grass steppe, the Southwestern desert grasslands, and communities dominated by annual grasses in California and S Idaho. Recognition of these stable states and models describing them are needed to develop new concepts about range condition. The model presently used assumes a single stable state (climax) and that the stages of secondary succession on improving rangelands are the reverse of the stages of retrogression. Alternative models presented include the "cup in ball' analogy, the state-and-transition model, and others. One assumption of the current range condition model is that a reduction in grazing pressure and an improvement in grazing management will result in range improvement. If a vegetation type is in a stable lower successional stage, it normally will not respond to change in grazing or even removal of grazing. -from Author
Grasshopper investigations on Montana rangelands
- N L J C Anderson
- Wright
Anderson, N. L. & J. C. Wright. 1952. Grasshopper
investigations on Montana rangelands. Mont. Agric.
Exp. Stn. Bull. 486.
Biological control of western rangeland grasshoppers with exotic predators and parasitoids: potential benefits, costs, and alternatives
Bomar, C. R. & J. A. Lockwood [eds.]. 1991. Biological control of western rangeland grasshoppers with
exotic predators and parasitoids: potential benefits,
costs, and alternatives. Wyo. Agric. Exp. Sm. Bull.
B-958.
Differentiation and ecology of common Catantopinae and Cyrtacanthacridinae nymphs (Orthoptera: Acrididae) of Idaho and adjacent areas
- M A Brusven
Brusven, M. A. 1972. Differentiation and ecology of
common Catantopinae and Cyrtacanthacridinae
nymphs (Orthoptera: Acrididae) of Idaho and adjacent areas. Melanderia 9: 1-31.
Grasshoppers (Acrididae) of Colorado: identification, biology, and. management
- J L T S Capinera
- Sechrist
Capinera, J. L. & T. S. Sechrist. 1982. Grasshoppers
(Acrididae) of Colorado: identification, biology, and.
management. Colo. State Univ. Exp. Sm. Bull.
584S.
Ecological benefits and risks associated with the introduction of exotic species for biological control of agricultural pests
- R I J R Carruthers
- Coulson
Carruthers, R. I. & J. R. Coulson. 1993. Ecological
benefits and risks associated with the introduction
of exotic species for biological control of agricultural pests. Proceedings, National Academy of Science Workshop on Ecological Risk Management,
Washington, DC (in press).
Studies in the biology of North American Acrididae: development and habits. Proceedings, World's Grain Exhibition Conference
- N Criddle
Criddle, N. 1933. Studies in the biology of North
American Acrididae: development and habits. Proceedings, World's Grain Exhibition Conference. 2:
474-494.
Economic analysis of alternative grasshopper control strategies on rangelands
- R M M D Davis
- Skold
Davis, R. M. & M. D. Skold. 1990. Economic analysis of alternative grasshopper control strategies on
rangelands, pp. 108-117. In Cooperative grasshopper integrated pest management project annual report, USDA-APHlS-PPQ,
Boise, ID.