Nontarget effects of insecticides on biological control agents: insights from red pine forests and global challenges in forest pest management

Biological control is the use of an organism, the biological control agent (BCA), to control the population of another organism, the pest. While BCAs are used around the world and in a variety of agricultural contexts, increasing the uptake would be beneficial to key goals of sustainable agriculture. To do so, there is the desire for improving BCAs, either in terms of their production, their performance, or the reduction of non-target effects after release. One way to improve BCAs is to use a genetics approach with next-generation sequencing and genomics. The study of genetics is essentially about evolution and inheritance, and its application on BCAs is straightforward: are the traits that we are interested in, such as parasitism rate for parasitoid wasps or starvation resistance for predatory bugs, 1) heritable, and 2) able to be improved without deleterious (side-)effects? Is there enough genetic variation within a population to select for improvement of these traits? While these scenarios can be used for improving the BCAs themselves, the way that BCAs are monitored, stored, and assessed for non-target effects can also be improved using genetics and/or genomics. This thesis and the work within involved generating genomic results and resources for five biological control agents (including a predatory mite, two parasitoid wasps, and a predatory mirid bug), complete with context and suggestions for future directions. This thesis is also intended to act as a sort of guidebook for biological control practitioners considering genome projects. The introduction (Chapter 1) begins with defining an anthology, and the intention to treat this thesis as such. After introducing concepts of biological control, genetics and genomics, and the international project behind this thesis (BINGO-ITN), the research chapters begin. Chapter 2 contains a systematic review of biological control literature centered on documenting the amount of genetic variability research on BCAs, ending with a call for more rigorous reporting of variables such as heritability and evolvability. Chapter 3 contains a previously published work on whole genome sequencing via nanopore MinION technology and resulting microsatellite generation and population genetics of the predatory mite, Amblyseius swirskii. Chapter 4 and Chapter 5 are both in the style of genome reports, reduced-length manuscripts that, while destined for peer-review, are more straight to the point of describing genomes and any resulting analyses. Chapter 4 is the linked-read de novo annotated genome of parasitoid wasp Bracon brevicornis and resulting analyses into a putative region related to complementary sex determination, a defining feature of this parasitoid. Chapter 5 contains the hybrid de novo annotated genome of parasitoid wasp Trichogramma brassicae, where long- and short-read technology were used on a strain that was aided in its homozygosity by a Wolbachia infection. Chapter 6 features population studies and builds upon the reads generated in Chapter 5 by mining microsatellites from the short-reads to be used upon wild-caught lines of sister species Trichogramma evanescens. These German-origin lines were compared in a variety of ways using population genetics (the aforementioned microsatellites) as well as population genomics via pooled sequencing analyses and a de novo (unannotated) genome. Chapter 7, the final research chapter, contains the linked-read de novo annotated genome of predatory mirid Nesidiocoris tenuis, an important BCA used throughout the Mediterranean that is also considered a pest in other areas of the world. In addition to the genome, additional analyses include bacterial decontamination (leading to putative symbiont identification), potential lateral gene transfer events (though it is difficult to qualify initially), population genomics, and cytogenetic investigations into karyotype, sex determination system, unique satellites, and the presence/absence of the insect ancestral telomeric motif. This variety of investigations offer a taste of what is possible with a genome, acting as inspiration for future research. The thesis/anthology is wrapped up in Chapter 8, the synthesis, where the preceding research chapters are examined in the light of themes presented in the introduction, and more general notes over the success (or failure?) of these various projects. Appendices contain four summaries (English, Dutch, German, and Spanish) as well as Acknowledgements, About the Author, and About the Artwork found within the thesis (each chapter title has a unique accompanying illustration).

Entomopathogenic fungi are a group of fungi that infect and kill insects to obtain nutrients, thereby contributing to the natural regulation of insect populations. In recent years, they have been increasingly utilized as biological control agents, particularly in response to the rising prevalence of pesticide-resistant pests in agricultural systems. Representative examples include Beauveria bassiana and Metarhizium anisopliae, which are regarded as natural enemies of pests in agroecosystems. Since the first report of Korean oak wilt disease in 2004, the disease has continuously spread across the country and causes severe damage to deciduous oak species, especially Quercus mongolica. Although many efforts have been made to effectively control the disease, including chemical treatments, the control efficacy was shown to be low, and given the environmental side effects arising from the use of insecticides, there has been a demand for alternative control strategies. Integrated Pest Management in forests promotes ecological sustainability by reducing chemical pesticide use, conserving biodiversity, and enhancing long-term forest health. In this study, to mitigate issues with disease management strategies, assessments were made on three entomopathogenic fungi, B. bassiana, M. anisopliae, and Purpureocillium lilacinum, as potential biological control agents against oak wilt disease and its insect vector, Platypus koryoensis. In this regard, we investigated the insecticidal efficacy and LT50 of each entomopathogenic fungus, and the results showed that all three entomopathogenic fungal strains exhibited fast insecticidal effects against the insect vector, P. koryoensis, with M. anisopliae showing the fastest action, recording a lethal time to 50% mortality (LT50) of 58.7 h. The spores of M. anisopliae were found to be sensitive to high temperatures, while demonstrating a relatively high germination rate under UV exposure and strong initial germination ability at low temperatures.

Infestation of fruits by native and invasive fruit flies causes significant economic losses. In most cases, incidence of 'regulated' dangerous fruit flies in orchards results in restrictions on export of fruits from such places to international markets. Unfortunately, use of insecticides applied on foliage and fruits does not kill the fruit-to-soil stages of fruit flies. However, diverse biological control agents (BCAs) do so. Thus, prevalence of native and invasive fruit flies in orchards will require that a combination of BCAs is included in integrated pest management (IPM) programmes. In the case of Bactrocera dorsalis Hendel and other economically important fruit flies found in sub-Saharan Africa (SSA), use of classical biocontrol approach involves concomitant releases of two exotic parasitoids (Fopius arisanus Sonan and Diachasmimorpha longicaudata Ashmead). These non-native wasps may have complemented the indigenous parasitoids in combination with application of entomopathogenic fungi (EPFs) and conservation of predatory ants (Oecophylla longinoda Latreille, with O. smaragdina) in fruit fly IPM plans. Consequently, some levels of decline in fruit infestation have been observed. Although interspecific interactions between BCAs against several insect pests have produced varying results, including threatening the survival of other BCAs, the prevalence of B. dorsalis in orchards across SSA requires further research to investigate effects of coalescing biocontrol approaches in IPM strategies. Therefore, future research into combining parasitoids, EPFs and entomopathogenic nematodes, in addition to conservation of predatory ants (O. longinoda, O. smaragdina and others) in IPM plans may improve the effectiveness of currently used strategies for the management of fruit-infesting tephritids. © 2021 Society of Chemical Industry.

Biological control agents against the cabbage stem flea beetle in oilseed rape crops

Chemical insecticides have been an important tool in the management of forest insect pests in Canadian forests. Aerial application of insecticides began in the 1920s and expanded greatly after World War II with the widespread adoption of DDT primarily for the suppression of spruce budworm,Choristoneura fumiferanaClemens (Lepidoptera: Tortricidae), and other defoliating insects. Significant progress was made in the development of new chemical insecticides and formulations including fenitrothion and tebufenozide, as well as technology for the application of insecticides against various insect pests. However, widespread opposition to the use of chemical insecticides in forest management has led to significant reductions in the number of insecticides registered for use in Canadian forests. Developments in the past 20 years have focussed on new insecticides, formulations, and technologies that seek to limit the impacts on non-target organisms and subsequent ecosystem effects. These developments have resulted in significant improvements in the management of traditional management targets, such as the spruce budworm (Choristoneura fumiferana(Clemens); Lepidoptera: Tortricidae) but also the management of invasive species, especially wood-boring beetles (Coleoptera: Buprestidae, Cerambycidae).

Non-target effects of bacterial biological control agents suppressing root pathogenic fungi

Forest pest management sociopolitics

Target and non-target impact of systemic insecticides on a polyphagous aphid pest and its parasitoid

The use of some systemic insecticides has been banned in Europe because they are toxic to beneficial insects when these feed on nectar. A recent study shows that systemic insecticides can also kill beneficial insects when they feed on honeydew. Honeydew is the sugar-rich excretion of hemipterans and is the most abundant carbohydrate source for beneficial insects such as pollinators and biological control agents in agroecosystems. Here, we investigated whether the toxicity of contaminated honeydew depends on i) the hemipteran species that excretes the honeydew; ii) the active ingredient, and iii) the beneficial insect that feeds on it. HPLC-MS/MS analyses demonstrated that the systemic insecticides pymetrozine and flonicamid, which are commonly used in Integrated Pest Management programs, were present in honeydew excreted by the mealybug Planococcus citri. However, only pymetrozine was detected in honeydew excreted by the whitefly Aleurothixus floccosus. Toxicological studies demonstrated that honeydew excreted by mealybugs feeding on trees treated either with flonicamid or pymetrozine increased the mortality of the hoverfly Sphaerophoria rueppellii, but did not affect the parasitic wasp Anagyrusvladimiri. Honeydew contaminated with flonicamid was more toxic for the hoverfly than that contaminated with pymetrozine. Collectively, our data demonstrate that systemic insecticides commonly used in IPM programs can contaminate honeydew and kill beneficial insects that feed on it, with their toxicity being dependent on the active ingredient and hemipteran species that excretes the honeydew.

Do male and female family forest landowners have different training needs? A case study from Georgia, United States

Preface. Acknowledgments. Contributors. Part 1: Perspectives. 1. Critical Issues Related to Nontarget Effects in Classical Biological Control of Insetcs L.E. Ehler. 2. Nontarget Effects of Biological Control: What Are We Trying to Miss? J.A. Lockwood. 3. The Frequency and Strength of Nontarget Effects of Invertebrate Biological Control Agents of Plant Pests and Weeds P. Stiling, D. Simberloff. 4. The Impact of Nontarget Concerns on the Practice of Biological Control R.H. Messing. Part 2: Parasitoids and Predators. 5. Predicting the Risk from Biological Control Agent Introductions: A New Zealand Approach B. Barratt, et al. 6. Parasitoid Drift in Hawaiian Pentatomoids P.A. Follett, et al. 7. Evaluating Nontarget Effects of Classical Biological Control: Fruit Fly Parasitoids in Hawaii as a Case Study J.J. Duan, R.H. Messing. 8. Trichogramma Nontarget Impacts: A Method for Biological Control Risk Assessment D.B. Orr, et al. 9. Coccinellid Introductions: Potential for and Evaluation of Nontarget Effects J.J. Obrycki, et al. 10. Food Webs as a Tool for Studying Nontarget Effects in Biological Control J. Memmott. Part 3: Weeds. 11. Why Things Bite Back: Unintended Consequences of Biological Weed Control P.B. McEvoy, E.M. Coombs. 12. Importation Protocols and Risk Assessment of Weed Biological Control Agents in Australia: The Example of Carmenta nr ithacae T. Withers, et al. 13. Negative Ecological Effects of the Musk Thistle Biological Control Agent, Rhinocyllus conicus S.M. Louda. 14. Biological Control of Musk Thistle: A Reassessment J.R. Nechols. Part 4: Pathogens. 15. Predicting the Host Range of Entomopathogenic Fungi A.E. Hajek, L. Butler. 16. Monitoring the Effects of Bacillus thuringiensis kurstaki on Nontarget Lepidoptera in Woodlands and Forests of Western Oregon J.C. Miller. 17. Environmental Impacts of Entomopathogenic Nematodes Used for Biological Control in Soil M. Barbercheck, L.C. Millar. Index.

This paper addresses the biodiversity of forest ecosystems as an important criterion of sustainable forest management. Possibilities of biodiversity classification and evaluation are discussed and the situation in the Czech Republic described, including information on measures proposed for maintaining, preserving and increasing biodiversity.The political tools on biodiversity protection, including the Helsinki resolution H2 are discussed. On the basis of numbers of forest plants and trees, it is shown how small part of the global biodiversity is represented by the forestry in Central Europe.Some most important aspects of the current unsatisfactory state of biodiversity of the forest ecosystems in the Czech Republic are described. The data have been collected and elaborated from the Report on forestry of the Czech Republic, Red List of plant communities and protected and threatened species of the Czech flora. Today, unsuitable species composition is considered to be one of the main causes of decline and threat to many plant and animal species and whole forest communities, resulting in a lower level of biodiversity.Alternatives of measuring and evaluating biodiversity are mentioned. In conclusion, a survey of the most important measures for sustaining and increasing the biodiversity of forest ecosystems, as proposed and implemented in the framework of the ecological transformation of forest management in Czech Republic, is presented. It is for instance suggested changes in tree species composition, improvement of the forest typology, realisation of measures on preservation and reproduction of gene resources of forest tree species, deflection of clear-cut management system, increased share of the natural regeneration, increased care for the specific biotopes, creation and use of the “generals” of the regional system of ecological stability and reduction of damages by hoofed game. The attention is pointed to gene bases, their characteristic, purpose and management as a basic measure of forest management for sustaining and improving the biodiversity of forest ecosystems.

The indiscriminate use of synthetic pesticides has brought undesired problems to human health, agriculture, and the environment. Integrated Pest Management (IPM) and Biological Control (BC) programs, which are based on minimum use of pesticides, are seen as alternative, more ecological solutions to the unintended problems associated with pesticide use. These programs combine the introduction, augmentation, and/or conservation of pest natural enemies, with other protection tools. Although patents and the process of commercialization of microorganisms has been the subject of various reviews, macroorganisms used for pest and disease control have stimulated less comprehensive analyses. From our review of patents, there has been an enormous increase in the number of macroorganism-related patents registered in the last two decades. Private companies own 65% of all these patents. Rearing methods and crop protection strategies are the main intellectual property patented, with parasitoid wasps and predatory mites being the primary Biological Control Agent (BCA) focus of patents. Among countries, Japan was the first country with these types of patents, followed by the United States, Canada and China. Increasing concern for pesticide risks by governments and the public is seen as the main impetus for change in "traditional" crop protection practices and for investment in other more ecological products like BCAs.

Beta-cypermethrin is widely applied in Korean pine (Pinus koraiensis Siebold & Zucc.) seed orchards to control cone- and seed-infesting moths (e.g., Dioryctria spp.), yet its Wsublethal risks to non-target beneficial arthropods remain insufficiently characterized. Here, we systematically evaluated the ecological and physiological consequences of beta-cypermethrin exposure on the key parasitoid wasp Baryscapus dioryctriae Yang & Song, an important biological control agent in P. koraiensis forests. Adult wasps were exposed to LC30 and LC50 residue concentrations, and sublethal effects were quantified across reproductive, developmental, and biochemical endpoints over two generations. Sublethal exposure resulted in significant reductions in parasitism rates and offspring emergence, as well as altered developmental durations and adult longevity in both F0 and F1 generations. Enzymatic assays revealed time-dependent activation of detoxification enzymes (GST, CarE, AChE) alongside suppression of antioxidant defenses (CAT strongly; SOD early with partial recovery; POD biphasic), consistent with a sustained oxidative-stress burden. LC-MS/MS residue analysis further confirmed the accumulation and slow clearance of both beta-cypermethrin and its metabolite 3-phenoxybenzoic acid (PBA) within parasitoid tissues. These findings collectively demonstrate that even non-lethal concentrations of beta-cypermethrin can undermine the ecological fitness and persistence of B. dioryctriae, posing a tangible threat to the sustainability of biological control services. To safeguard beneficial parasitoids, integrated pest management strategies must incorporate selective insecticide use and exposure mitigation, especially in forest habitats where biological control is indispensable.

Simple SummaryParasitoid wasps are well-known biological control agents for arthropod pests in agricultural and forest ecosystems. The stored food product environment is generally also favourable for the parasitoid wasps of the insect pests that infest those food products. Nevertheless, most studies suggest that biological control can reduce pest populations sufficiently only when combined with additional pest-management tools. Combining natural enemies and synthetic chemical pesticides is one of the main challenges in integrated pest management (IPM). We estimated, for the first time, the naturally occurring parasitoid community in grain stores before and after use of synthetic chemical pesticides. There is strong evidence that despite the immediate effect of the pesticides on the parasitoid community, over time, the community can recover. Undoubtedly, a lot of research, particularly of the nature of parasitoid wasps’ recovery in grain-storage facilities, is still required. This will reduce chemical use and implement biological control as a successful and important component of stored-product IPM.Insect contamination of stored grain is a major concern for the grain industry. Phosphine is currently the standard fumigant used to control insect pests in stored grain. However, some species and populations of insects that infest stored grain exhibit resistance to this fumigant and consumers are concerned about pesticide residues. Therefore, alternative methods of effective pest control are needed to partially or completely replace the use of phosphine. There is growing interest in biological control via parasitoid wasps. However, there is evidence that biological control will succeed only if used alongside other pest-management measures. Integrating biological control with the use of chemical insecticide is challenging and may lead to severe reductions in parasitoid survival and success. The main aim of the current study is to shed light on a greatly overlooked issue: the parasitoid community found in stored grain before and after phosphine treatment. The current study results indicate that there is a high level of parasitoid biodiversity within grain stores. We found common parasitoids at both semi-arid and Mediterranean sites, suggesting that those parasitoids can be active across a wide range of abiotic conditions. This research indicates that the community may recover even though phosphine has an immediate negative effect on a parasitoid community. Nevertheless, the parasitoid wasps seem to reduce the host population insufficiently. In light of the findings presented here, those interested in implementing pest-management strategies that include both phosphine treatment and biological control should consider conservation and augmentation of the naturally occurring parasitoid population. These studies should take into account interactions between and within parasitoid populations and phosphine distribution within the grain storage. To limit the effect of phosphine on the parasitoids, pest-management strategies should also reflect careful consideration of the timing of phosphine treatment and the need for sufficient refuge for the parasitoids.