Arthropod Biological Control Agents Research Articles

Publisher Correction to: Integrating adverse effect analysis into environmental risk assessment for exotic generalist arthropod biological control agents: a three-tiered framework

Due to typesetting errors, Table 5 was not displayed correctly in the initial online publication. The original online article has been corrected.

Impact of heat stress on the development of egg and adult coccinellid Serangium japonicum: evidence for cross-stage and cross-generation effects

Arthropod biological control agents are at risk due to climate change, since heat stress negatively impacts their life history traits. Here, we investigated ontogenetic variation of thermal sensitivity in an important whitefly predator, Serangium japonicum Chapin (Coleoptera: Coccinellidae). In particular, we evaluated the impact of heat shock on survival rate, development, and reproduction of S. japonicum , and checked whether the negative effects resulting from heat stress are stage-related. The two most heat-tolerant stages of S. japonicum (egg and adult) were exposed to heat shock treatments at 36, 39, and 42 oC for 2 h, and 36 and 39 oC for 4 h. We found that heat shock significantly reduced egg-to-adult survival rate, extended egg-to-adult development time, and decreased fecundity and oviposition period compared to control (27 oC). The sex ratio however was not affected. Eggs exposed to heat shock led to adults whose weight and longevity were considerably reduced. The detrimental effects that resulted from heat shock were carried over to later life stages and even the next generation. Those carry-over effects were independent of stage except for egg-to-adult development time and adult weight. Our results suggest that releasing eggs or adults into fields or greenhouses makes little difference in reducing any negative impact on the developmental performance of S. japonicum induced by heat stress in a warming climate.

Exotic generalist arthropod biological control agents: need to improve environmental risk assessment to ensure safe use

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.

Integrating adverse effect analysis into environmental risk assessment for exotic generalist arthropod biological control agents: a three-tiered framework

Environmental risk assessments (ERAs) are required before utilizing exotic arthropods for biological control (BC). Present ERAs focus on exposure analysis (host/prey range) and have resulted in approval of many specialist exotic biological control agents (BCA). In comparison to specialists, generalist arthropod BCAs (GABCAs) have been considered inherently risky and less used in classical biological control. To safely consider exotic GABCAs, an ERA must include methods for the analysis of potential effects. A panel of 47 experts from 14 countries discussed, in six online forums over 12 months, scientific criteria for an ERA for exotic GABCAs. Using four case studies, a three-tiered ERA comprising Scoping, Screening and Definitive Assessments was developed. The ERA is primarily based on expert consultation, with decision processes in each tier that lead to the approval of the petition or the subsequent tier. In the Scoping Assessment, likelihood of establishment (for augmentative BC), and potential effect(s) are qualitatively assessed. If risks are identified, the Screening Assessment is conducted, in which 19 categories of effects (adverse and beneficial) are quantified. If a risk exceeds the proposed risk threshold in any of these categories, the analysis moves to the Definitive Assessment to identify potential non-target species in the respective category(ies). When at least one potential non-target species is at significant risk, long-term and indirect ecosystem risks must be quantified with actual data or the petition for release can be dismissed or withdrawn. The proposed ERA should contribute to the development of safe pathways for the use of low risk GABCAs.

Contributions to improve current environmental risk assessment procedures of generalist arthropod biological control agents (GABCAs) in Argentina

Argentina has over 100 years of experience in classical biological control, mostly based on the importation of biological control agents (BCAs) against arthropod pests. We present the state-of-the-art of the importation regulatory framework from the last 30 years to date. We also applied a part of a recent developed environmental risk assessment (ERA) methodology to analyze retrospectively the potential negative effects on non-target species of 15 BCAs (12 parasitoids and three predators) imported since 1996 in Argentina, supported by the published literature (Tier 1 Scoping Assessment and Tier 2 Screening Assessment). We demonstrated that the previously imported species could have negative effects on non-target species [Adverse Effect risk characterization > 5 for ERA categories 2 (Reduction of native natural enemies), 3 (Reduction in herbivory) and 4 (Reduction in valued species)], which would be worth evaluating with a Definitive Assessment (Tier 3) and field research to determine if any were actually occurring. We discuss some suggestions for government organizations, state officials and decision makers, scientific researchers, and biological control practitioners to improve the current evaluation for the introduction of new BCAs into Argentina.

Risk assessment procedures for biological control agents in New Zealand: two case studies for generalists

New Zealand’s indigenous and productive ecosystems are highly vulnerable to invasive species: therefore, New Zealand has stringent biosecurity legislation which encompasses the introduction of new biological control agents. To introduce a new agent, an application is made to the Environmental Protection Authority (EPA). The risk assessment carried out by the applicant is reviewed and a decision is made by an independent committee following public submissions and Māori consultation. An application will be declined if it is likely the new agent will cause significant adverse impacts on any indigenous species within its natural habitat, on natural habitats or on New Zealand’s inherent genetic diversity. Contrasting case studies are presented on two generalist arthropod biological control agents, one for a predatory mirid Macrolophus pygmaeus (Rambur) (Hemiptera: Miridae) where the application was declined, and the other a predatory mite Neomolgus capillatus (Kramer) (Acarina: Bdellidae) which was considered for an application.

Efficacy of spinosad bait sprays to control Bactrocera oleae and impact on non-target arthropods

A field study was conducted during 2005 and 2006 in Terra Quente, northeastern Portugal, to evaluate the efficacy of the spinosad-based insecticide Spintor Cebo® (Dow Agrosciences Iberica, S.A.) against the olive fruit fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae), as well as the impact of the treatments on non-target arthropods. Results suggest that this insecticide could be as effective as dimethoate and since it was reported as having more benign toxicological and ecological profiles, it seems to be a good alternative to control the pest in Continental Mediterranean climates such as Terra Quente. However, its use should be evaluated carefully, mainly in conditions that increase the arthropod biological control agents’ propensity for feeding on it (e.g. absence of pollen, nectar and honeydews) to identify unintended impacts on conservation biological control of olive pests as a result of its application.

Effect of reduced risk pesticides on greenhouse vegetable arthropod biological control agents

Arthropod biological control agents (BCAs) are commonly released for greenhouse vegetable insect pest management. Nevertheless, chemicals remain a necessary control tactic for certain insect pests and diseases and they can have negative impacts on BCAs. The compatibility of some formulated reduced risk insecticides (abamectin, metaflumizone and chlorantraniliprole) and fungicides (myclobutanil, potassium bicarbonate and cyprodinil + fludioxonil) used, or with promise for use, in Canadian greenhouses with Orius insidiosus (Say), Amblyseius swirskii (Athias-Henriot) and Eretmocerus eremicus (Rose & Zolnerovich) was determined through laboratory and greenhouse bioassays. Overall, the insecticides and fungicides were harmless as residues to adult BCAs. However, abamectin was slightly to moderately harmful to O. insidiosus and A. swirskii in laboratory bioassays, whereas metaflumizone was slightly harmful to E. eremicus. In general, these products appear safe to use prior to establishment/release of these adult BCAs.

Florida's Established Arthropod Weed Biological Control Agents and Their Targets

ENY853, a 3-page fact sheet by J. P. Cuda and J. H. Frank, describes the role of biological control agents in controlling nonnative invasive weeds, lists the arthropod biological control agents that are established for seven invasive weeds, and provides links to additional resources. Includes references. Published by the UF Department of Entomology and Nematology, September 2009. ENY-853/IN779: Florida's Established Arthropod Weed Biological Control Agents and Their Targets (ufl.edu)

Predicting the distribution ofEccritotarsus catarinensis, a natural enemy released on water hyacinth in South Africa

AbstractWater hyacinth [Eichhornia crassipes(Mart.) Solms (Pontederiaceae)] is the most damaging aquatic weed in South Africa, where five arthropod biological control agents have been released against it. The most recent introduction ofEccritotarsus catarinensis(Carvalho) (Heteroptera: Miridae) has failed to establish permanent populations at a number of sites in South Africa where water hyacinth is a problem. Cold winter temperatures at these sites are assumed to be the reason for these establishment failures. This assumption was tested by investigating the thermal physiology of the mirid, then incorporating these data into various predictive distribution models. Degree‐day models predict 3–14 generations per year at different localities in South Africa, and five generations at a Johannesburg site where the mirid failed to overwinter. The inability to develop sufficiently rapidly during winter months may hinder overwintering of this insect, which was predicted to develop through only one generation during the winter months of April to August in Johannesburg. A CLIMEX model also showed that cold stress limits the mirid's ability to overwinter in the interior of the country, while determination of the lower lethal limit (–3.5 °C) and critical thermal minimum (1.2 ± 1.17 °C) also indicated that extreme temperatures will limit establishment at certain sites. It is concluded thatE. catarinensisis limited in its distribution in South Africa by low winter temperatures.

The influence of flower morphology and nectar quality on the longevity of a parasitoid biological control agent

Conservation biological control aims to enhance the efficacy of arthropod biological control agents, such as parasitoids, partly by providing them with access to floral nectar. However, the suitability of a flower species for providing nectar to a parasitoid is dependent on the morphologies of the parasitoid and the flower, as well as on the quality of the nectar. The effects of seven flower species on the longevity of Microctonus hyperodae (Hymenoptera Braconidae), a parasitoid of the Argentine stem weevil, Listronotus bonariensis (Coleoptera: Curculionidae), were measured in the laboratory. The flowers were phacelia (Phacelia tanacetifolia), buckwheat (Fagopyrum esculentum), alyssum (Lobularia maritima), coriander (Coriandrum sativum), white clover (Trifolium repens), red clover (Trifolium pratense) and white mustard (Sinapis alba). The results suggested M. hyperodae was unable to reach nectar of red clover, white clover, alyssum and phacelia, but was able to gain access to the nectar of the other three species. However, only buckwheat and coriander increased its longevity. Flower corolla aperture and depth probably determined the parasitoid’s access to nectar. Accessible nectars were analyzed for sugar composition and the effect of the sucrose/(glucose + fructose) ratio on nectar suitability was assessed. The relevance of these results to other hymenopteran parasitoid species is discussed in terms of selecting the most appropriate floral diversity in agricultural extensification programmes.

History and Future of Introduction of Exotic Arthropod Biological Control Agents in Spain: A Dilemma?

The first documented introduction of an exotic invertebrate biological control agent (IBCA) in Spain occurred in 1908. Sixty-four additional species have been introduced since then. Information, both previously recorded and original data, on the species introduced for pest control is summarized. Most of the introduced IBCAs focused on citrus pests and homopterans clearly predominate among target phytophagous species. Success has been more frequent for IBCAs used in seasonal inoculative strategies (50.0% of cases) than in classical biological control programs (17.1% of cases). Concerns about potential non-target effects of such species are increasing, but post-release evaluation has often been insufficient to draw any conclusions about them. Most of the beneficial species introduced in Spain were parasitoids (n = 53), and the remaining species were predators (n = 12). Only four parasitoids are considered specialized monophagous natural enemies. The mean number of host species parasitized by parasitoids is 15.2, whereas the mean number of prey species attacked by predators is 21.2. Therefore, polyphagy appears to be quite common among the IBCAs that have been introduced in Spain. The rationale guiding many of these introductions in the past would not be acceptable nowadays. Since classical biological control is such a valuable strategy for pest control, straightforward protocols to evaluate exotic candidate species are urgently needed.

Selecting arthropod biological control agents against arthropod pests: Can the science be improved to decrease the risk of releasing ineffective agents?

With greater emphasis being placed on management of the risks attached to natural enemy releases for biocontrol programs and the need to justify research budgets, the efficient selection of effective natural enemies is increasingly important. Historically there has been little agreement regarding how or whether this can be accomplished. Recent studies have demonstrated that there is good correspondence between insect host-finding behavior and attack rates in well-designed laboratory studies and their performance of this behavior in the field. Success in measuring efficacy of candidate agents remains somewhat of an art due to the multitude of factors influencing efficacy, but will be improved by attention to: (1) characterization of natural enemy candidates using morphological taxonomy or genetic markers at the onset of a program, (2) climatic matching candidate agents when possible, and (3) evaluations in semi-field or field cage conditions following quarantine evaluations whenever possible before proceeding with widespread releases. The application of these principles is discussed in regard to US biocontrol programs for Bemisia tabaci (Gennadius), Lygus spp., and Aphis glycines Matsumura. Proper project planning and interdisciplinary cooperation will enhance the chances for a successful project.

Failure of Eccritotarsus catarinensis, a biological control agent of waterhyacinth, to persist on pickerelweed, a non-target host in South Africa, after forced establishment

Abstract Waterhyacinth (Eichhornia crassipes) is the most damaging aquatic weed in South Africa, where five arthropod biological control agents have been released to date. The most recent introduction, a South American mirid, Eccritotarsus catarinensis, was shown to utilize Pontederia cordata (pickerelweed) during laboratory host-specificity trials. This did not influence the decision to release the mirid in South Africa, where the exotic pickerelweed is a declared invader. However, in the United States of America where waterhyacinth is also a problem, the possibility of spillover damage on indigenous pickerelweed may preclude the release of the mirid. In this study, E. catarinensis did not establish on pickerelweed in the field in South Africa, following either confined releases, where the mirids were initially released into sleeve cages, or unconfined releases where mirid-infested pickerelweed plants were placed amongst pickerelweed stands. We thus recommend that E. catarinensis be considered as an additional control agent of waterhyacinth in North America.

Biocontrol of Pests of Apples and Pears in Northern and Central Europe - 3. Predators

Predators of apple and pear pests in northern and central Europe and their use as biological control agents are reviewed. Many natural enemy species are specialized feeders and are able to respond to the population dynamics of particular pest species. The most oustandingly successful example of this is the use of phytoseiid mites, particularly Typhlodromus pyri , against phytophagous pest mites in apple. This mite management strategy is now widespread throughout European apple growing regions. Another example is the use of Anthocoris nemoralis against pear psyllids, Cacopsylla pyricola and C. pyri . Several groups of naturally occurring polyphagous predators, such as chrysopids, coccinellids, syrphids and spiders, also prey on a number of pest species in orchards, contributing generally to the reduction in pest populations. However, they are unlikely alone to prevent pest damage fully and reliably. In seeking biological control opportunities for a particular pest, these polyphagous natural enemies are unlikely to be a high priority. An exception, due to its abundance in orchards, is the common earwig, Forficula auricularia , although this predator may also cause some fruit injury. Another option to consider when reviewing possibilities for biological control in orchards is the introduction of biological control agents. The success rate of this approach, using arthropod predators to control pests of field crops, has been generally poor. Furthermore, mass production methods for predators are likely to be difficult and very costly. The biological supplies industry is constantly seeking culture techniques, largely for arthropod biological control agents of pests of protected crops. It is possible that some future advance may be relevant to orchards, though currently available predators do not appear promising. A careful economic appraisal of the feasibility of use of any potential biological control agent would be prudent before embarking on research.

The pathogenicity of an Australian isolate of Acremonium zonatum to water hyacinth, and its relationship with the biological control agent, Neochetina eichhorniae

The first description of Acremonium zonatum on water hyacinth in Australia is made. Its pathogenicity was studied as part of the search for a microorganism already present in Australia which could be developed as a mychoherbicide to supplement the arthropod biological control programme in this country. Following inoculation with A. zonatum, extensive leaf infections developed, favoured by injury and free moisture, but new leaves continued to form. Feeding by the weevil, Neochetina eichhorniae, increased infection by A. zonatum in relatively dry conditions, but it is unlikely that this was due to feeding scars acting as ports of entry. A. zonatum spores were transported on the feet and in the digestive tract of the weevil. The growth of infected plants, estimated by standing crop, was reduced by 49% compared to the control. A further decrease occurred in infected plants infested by weevils, but the total reduction in growth was not equal to the sum of the individual effects of fungus and weevil. Infection did not develop in 15 other plant species inoculated with the Australian isolate of A. zonatum. Although not a virulent pathogen, A. zonatum has some favourable characteristics for consideration as a mycoherbicide and has not appeared antagonistic to N. eichhorniae in these studies. Its role probably lies in exerting a chronic stress on plants already under attack by arthropod biological control agents.

Intraspecific Variation in Levels of Pesticide Resistance in Field Populations of a Parasitoid, Aphytis melinus (Hymenoptera: Aphelinidae): The Role of Past Selection Pressures

Thirteen populations of Aphytis melinus DeBach, a key biological control agent of California red scale, Aonidiella aurantii (Maskell), were collected from the citrus-growing regions of California. Each population’s history of exposure to insecticides was estimated by determining history of insecticide use at both local (in-grove) and regional (county-wide) geographical scales. Concentration/mortality regressions for five insecticides widely used in citrus were estimated for the populations. For each chemical, substantial variability existed in the responses of different populations. LC50’s were correlated with both in-grove and county-wide pesticide use histories; patterns of variability were best explained by results of a multiple regression analysis that combined the influences of these two histories. Roles of food limitation, migration, and host distribution in determining patterns and rates of evolution of pesticide resistance in arthropod biological control agents are discussed.