A modified DNA barcode approach to define trophic interactions between native and exotic pentatomids and their parasitoids.

The establishment of invasive Halyomorpha halys (Stål) outside of its native range may impact native species assemblages, including other pentatomids and their scelionid parasitoids. This has generated interest in defining species diversity and host-parasitoid associations in this system to better understand the impact of invasive alien species on trophic interactions in invaded regions. Information on scelionid-pentatomid associations in natural habitats is lacking, and species-level identification of these associations can be tenuous using rearing and dissection techniques. Naturally occurring pentatomid eggs were collected in areas where H. halys has established in Canada and were analysed using a modified DNA barcoding approach to define species-level trophic interactions. Identification was possible for >90% of egg masses. Eleven pentatomid and five scelionid species were identified, and trophic links were established. Approximately 70% of egg masses were parasitized; parasitism and parasitoid species composition were described for each species. Telenomus podisi Ashmead was the dominant parasitoid and was detected in all host species. Trissolcus euschisti Ashmead was detected in several host species, but was significantly more prevalent in Chinavia hilaris (Say) and Brochymena quadripustulata (Fabricius). Trissolcus brochymenae Ashmead and Tr. thyantae Ashmead were recorded sporadically. Parasitism of H. halys was 55%, and this species was significantly less likely to be parasitized than native pentatomids. The scelionid species composition of H. halys consisted of Te. podisi, Tr. euschisti and Tr. thyantae. Although these species cannot develop in fresh H. halys eggs, we demonstrate that parasitoids attempt to exploit this host under field conditions.

Seasonal climatic variations influence the efficacy of predatory mites used for control of western flower thrips in greenhouse ornamental crops.

The influence of seasonal greenhouse climate on the efficacy of predatory mites for thrips control was determined for potted chrysanthemum. Trials in controlled environment chambers, small-scale greenhouses and commercial greenhouses were conducted to determine which biological control agent-that is, Amblyseius swirskii Athias-Henriot or Neoseiulus cucumeris (Oudemans)-is more efficacious for control of western flower thrips, Frankliniella occidentalis (Pergande), in different seasons. Under simulated summer conditions, no differences were observed in the predation and oviposition rates of both predatory mites in the laboratory trials. However, small-scale greenhouse trials showed that A. swirskii performed better than N. cucumeris in summer (i.e., more efficacious thrips control, higher predator abundance and less overall damage to the crop). Under simulated winter conditions, laboratory trials demonstrated variable differences in predation rates of the two predatory mites. The small-scale greenhouse trials in winter showed no differences in thrips control and predatory mite abundance between the two predatory mites, but plants with A. swirskii had less damage overall. The results from the small-scale trials were validated and confirmed in commercial greenhouse trials. Overall, A. swirskii performed better in the summer and equally good or better (less damage overall) under winter conditions, whereas N. cucumeris is a more cost effective biological control agent for winter months.

Amblyseius swirskii in greenhouse production systems: a floricultural perspective.

The predatory mite Amblyseius swirskii Athias-Henriot is a biological control agent that has the potential to play an important role in pest management in many greenhouse crops. Most research on this predatory mite has focused on its use and efficacy in greenhouse vegetables. However, an increasing number of growers of greenhouse ornamental crops also want to adopt biological control as their primary pest management strategy and find that biological control programs developed for vegetables are not optimized for use on floricultural plants. This paper reviews the use of A. swirskii in greenhouse crops, where possible highlighting the specific challenges and characteristics of ornamentals. The effects of different factors within the production system are described from the insect/mite and plant level up to the production level, including growing practices and environmental conditions. Finally, the use of A. swirskii within an integrated pest management system is discussed.

A field study examining the effects of exposure to neonicotinoid seed-treated corn on commercial bumble bee colonies.

Neonicotinoid insecticides have been studied as possible contributors to bumble bee declines in North America and Europe. This has potential significance in corn agro-ecosystems since this crop is frequently treated with neonicotinoids and dominates much of the agricultural landscape in North America and Europe where bumble bees and other pollinators are commonplace. We conducted an experiment where commercial bumble bee (Bombus impatiens) hives were placed during pollen shed next to corn (Zea mays) fields that were grown from "conventional" seed that was treated with neonicotinoids, or "organic" seed that was not treated with pesticides. Samples of pollen were collected from corn plants for neonicotinoid residue analysis, pollen types carried by worker bees returning to hives were determined, and in autumn hives were dissected to measure various endpoints that serve as markers of colony vigor. Clothianidin was detected (0.1-0.8 ng/g) in pollen collected from all conventional fields, but was not detected in pollen from organic fields. Corn pollen was only rarely collected from bumble bee foragers and the vast majority of pollen was from wild plants around the corn fields. All hives appeared healthy and neonicotinoid seed treatments had no effect on any hive endpoints measured, except the number of workers, where significantly fewer workers were recovered from hives placed next to conventional fields (96 ± 15 workers per hive) compared to organic fields (127 ± 17 workers per hive). The results suggest that exposure during pollen shed to corn grown from neonicotinoid-treated shed poses low risk to B. impatiens.

Demographic trends in mixed Bemisia tabaci (Hemiptera: Aleyrodidae) cryptic species populations in commercial poinsettia under biological control- and insecticide-based management.

Bemisia tabaci (Gennadius) is an economically important pest of agricultural and ornamental plants worldwide and is now widely recognized as a cryptic species complex. In North America, B. tabaci is a particularly important pest of greenhouse poinsettia. In poinsettia production, two cryptic species from the B. tabaci complex, Mediterranean and Middle East Minor 1, often infest crops simultaneously. Differences in pesticide susceptibility between these two cryptic species have the potential to influence growers' management decisions, including the use of biological control or insecticides, and the choice of insecticide active ingredient. However, the demographic behavior of mixed-species infestations in commercial greenhouses has yet to be investigated. We conducted a survey of B. tabaci populations in commercial greenhouses in Ontario, Canada, and provide evidence that under biological control-based management, Middle East Minor 1 can displace Mediterranean, whereas under insecticide-based management Mediterranean populations will persist. Furthermore, we comment on implications of this behavior on the management of B. tabaci, and comment on methods used to identify B. tabaci cryptic species.

Host plant effects on the behaviour and performance of Amblyseius swirskii (Acari: Phytoseiidae).

Biological control in ornamental crops is challenging due to the wide diversity of crops and cultivars. In this study, we tested the hypothesis that trichome density on different host plants influences the behavior and performance of the predatory mite Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae). Behavioural observations of this predator in the presence or absence of prey (western flower thrips, Frankliniella occidentalis Pergande) (Thysanoptera: Thripidae) were done on leaf squares of ornamental plant species differing in trichome density (rose, chrysanthemum and gerbera) and compared to a smooth surface (plastic). Tomato leaves were used to observe the influence of glandular trichomes. The performance of A. swirskii was assessed by measuring predation and oviposition rate. Behaviour of A. swirskii was influenced by plant species. Up to a certain density of trichomes, trichome number had a negative effect on walking speed. It was highest on plastic, followed by rose. No differences were found among chrysanthemum, gerbera and tomato. Walking speed was slightly higher on disks without prey. Proportion of time spent walking was the same on leaf disks of all plant species, with and without prey. No effect of glandular trichomes on tomato leaves was seen. Most thrips were killed and consumed on gerbera, and least on rose. Predation rates on chrysanthemum and plastic were intermediate. In contrast, no differences in oviposition rate were found among plant species. The results of this study indicate that trichome density can explain some of the variability in efficacy of A. swirskii on different crops. Release rates of A. swirskii may need to be adjusted depending on the crop in which it is used.

Assessing the sterility and quality of gamma-irradiated pepper weevils, Anthonomus eugenii (Coleoptera: Curculionidae), toward the development of the sterile insect technique.

BACKGROUND: The pepper weevil (PW), Anthonomus eugenii, is an economically significant pest of cultivated Capsicum spp. pepper crops in North America where it remains a challenge to manage because of its cryptic immature life stages. The sterile insect technique (SIT) is a genetic pest management tactic that relies on the release of insects that have been sterilized with ionizing radiation to lower the population reproductive rate. Toward developing an effective PW-SIT program, this study has, for the first time, investigated the effects of gamma irradiation on the sterility and survival of this species. RESULTS: Among the array of doses tested, we found that pupal PW males and females irradiated at 110 Gy produced no adult offspring. Furthermore, females mated with a male irradiated at 110 Gy had high egg sterility (97.3%), and irradiated females nearly completely failed to lay eggs (97.5%). Individuals irradiated at this dose had a shortened lifespan (lethal time to 50% mortality values of 12 and 11 days for males and females, respectively) and quantitatively reduced spontaneous flight activity. The eclosion rate of PW pupae was not significantly reduced by any radiation treatment. CONCLUSION: This study suggests that PWs irradiated at a gamma radiation dose of 110 Gy as pupae could feasibly be used in a PW-SIT program, because both males and females were 100% sterile at this dose. These findings will inform the development of a SIT program that could considerably improve the sustainability and effectiveness of PW management in greenhouse and field pepper crops worldwide. © 2023 His Majesty the King in Right of Canada and The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. Reproduced with the permission of the Minister of Agriculture and Agri Food Canada.

Laboratory Investigations on the Potential Efficacy of Biological Control Agents on Two Thrips Species, Onion Thrips (Thrips tabaci Lindeman) and Western Flower Thrips (Frankliniella occidentalis (Pergande)).

Thrips biocontrol research in greenhouse crops has focused primarily on western flower thrips (WFT; Frankliniella occidentalis). However, recent outbreaks of onion thrips (OT; Thrips tabaci) in Ontario, Canada, demonstrate that biocontrol-based IPM programs for WFT do not control OT sufficiently to prevent crop losses. A lack of comparative studies makes it difficult to determine which program components for WFT are failing for OT. We conducted several laboratory trials examining the extent to which commercial biocontrol products kill OT compared to WFT. These included phytoseiid mites (Amblyseius swirskii, Neoseiulus cucumeris, Amblydromalus limonicus, Iphiseius degenerans), a large generalist predator (Orius insidiosus), an entomopathogenic fungus (Beauveria bassiana strain GHA), and entomopathogenic nematodes (Steinernema feltiae, S. carpocapsae, Heterorhabditis bacteriophora). In no-choice trials, A. swirskii and O. insidiosus consumed more OT than WFT (first instars and adults, respectively). In choice trials, A. swirskii, N. cucumeris, and O. insidiosus consumed more OT than WFT. Steinernema feltiae caused higher mortality in OT than WFT. There was no difference in mortality between thrips species exposed to other biocontrol agents. This suggests available tools have the potential to manage OT as well as WFT. Possible explanations why this potential is not realized in commercial settings are explored.

Modelling potential distribution of the invasive box tree moth across Asia, Europe, and North America.

The box tree moth Cydalima perspectalis (Walker) (Lepidoptera: Crambidae) (BTM) is a native moth throughout eastern Asia, having recently become invasive in Europe (2007) where it feeds on boxwood (= box tree), Buxus spp. The moth rapidly spread across Europe and the Caucasus causing damage to both ornamental and wild Buxus. In 2018, C. perspectalis was found in Toronto, ON, Canada, and has since spread south into the US. To better predict where the moth will establish and have significant impact on ornamental trade in North America, we used most recent scientific literature and distribution points to update the temperature and diapause indices of an existing ecoclimatic CLIMEX model. The model parameters provided a good fit for the potential distribution of BTM compared to its known distribution across eastern Asia and in Europe. Interestingly, our results suggest that the current native distribution in Asia is incomplete and that further expansion is also possible in its introduced range, especially in northern Europe, along the Mediterranean coast of Africa, and eastward to central Russia. In North America, the model predicts that most of North America should be climatically suitable for the moth's establishment, with the exception of Alaska and the northern territories of Canada, as well as higher elevations in the Rocky Mountains and southern hot and dry areas. Our study highlights the importance of the CLIMEX model to assess the risk of BTM spreading in its newly invaded areas, especially North America, and its use to help make decisions in terms of regulatory dispersal restrictions and choice of management options.

Toxicity of Five Plant Volatiles to Adult and Egg Stages of Drosophila suzukii Matsumura (Diptera: Drosophilidae), the Spotted-Wing Drosophila.

The environmental impact of methyl bromide (MB) has resulted in its phase out as an insecticidal fumigant except for critical use exempted categories. Consequently, there is an urgent need to develop an environmentally sustainable MB alternative fumigant. trans-Cinnamaldehyde (TC), benzaldehyde, allyl isothiocyanate (AITC), hexanal, and ethyl formate (EF) are naturally occurring plant volatiles with insecticidal properties. This study assessed the toxicity of these plant volatiles to adult and egg stages of the spotted-wing drosophila (SWD) (Drosophila suzukii Matsumura). The plant volatile treatments had a significant effect on adult SWD mortality. The descending order of toxicity to adult SWD was benzaldehyde > AITC > TC > hexanal > EF at a headspace concentration of 0.50 µL/L air for 24 h. All the volatiles, at a concentration of 4.00 µL/L air, significantly inhibited larval emergence from SWD eggs in artificial diet compared to the control. At a 0.50 µL/L air level, among the volatiles tested, only AITC exhibited 100% inhibition against larval emergence from SWD eggs in blueberry fruits after 24 h exposure. In summary, this study shows that all volatiles tested elicited varying degrees of toxicity toward SWD adults and eggs. However, AITC was the most efficacious volatile and the one with the greatest promise as a post-harvest fumigant for both adult and egg stages of SWD.

Contact toxicity of three insecticides for use in tier I pesticide risk assessments with Megachile rotundata (Hymenoptera: Megachilidae).

The current pesticide risk assessment paradigm may not adequately protect solitary bees as it focuses primarily on the honey bee (Apis mellifera). The alfalfa leafcutting bee (Megachile rotundata) is a potential surrogate species for use in pesticide risk assessment for solitary bees in North America. However, the toxicity of potential toxic reference standards to M. rotundata will need to be determined before pesticide risk assessment tests (tier I trials) can be implemented. Therefore, we assessed the acute topical toxicity and generated LD50 values for three insecticides: dimethoate (62.08 ng a.i./bee), permethrin (50.01 ng a.i./bee), and imidacloprid (12.82 ng a.i/bee). The variation in the mass of individual bees had a significant but small effect on these toxicity estimates. Overall, the toxicity of these insecticides to M. rotundata were within the 10-fold safety factor currently used with A. mellifera toxicity estimates from tier I trials to estimate risk to other bee species. Therefore, tier I pesticide risk assessments with solitary bees may not be necessary, and efforts could be directed to developing more realistic, higher-tier pesticide risk assessment trials for solitary bees.

Synthesis and Characterization of Ethyl Formate Precursor for Activated Release Application.

Ethyl formate (EF) is a generally recognized-as-safe flavoring agent commonly used in the food industry. It is a naturally occurring volatile with insecticidal and antimicrobial properties, promising as an alternate fumigant to methyl bromide which is undesirable due to its ozone depletion in the stratosphere and toxic properties. However, EF is highly volatile, flammable, and susceptible to hydrolytic degradation. These properties present considerable end-use challenges. In this study, a precursor of EF was synthesized via the condensation reaction of adipic acid dihydrazide and triethyl orthoformate to form diethyl N,N'-adipoyldiformohydrazonate, as confirmed by Fourier transformed infrared and solid-state nuclear magnetic resonance spectroscopies. Differential scanning calorimetry analysis showed that the precursor had a melting point of 174 °C. The physical properties of the precursor were studied using scanning electron microscopy and dynamic light scattering analysis, which showed that the precursor was made up of agglomerated particulates with irregular shapes and sizes. The resulting precursor was nonvolatile and remained stable under dry conditions but could be hydrolyzed readily to trigger the release of EF. The release behaviors of EF from the precursor was evaluated by citric acid-catalyzed hydrolysis, showing that 0.38 ± 0.008 mg EF/mg precursor was released after 2 h at 25 °C, representing about 98% of the theoretical loading. Both EF release rate and its total release amount decreased significantly (p < 0.05) with decreasing temperature and relative humidity. The conversion of the highly volatile EF into a solid-state precursor, in conjunction with the activated release strategy, can be useful for controlled release of EF for fumigation and other applications in destroying insect pests and inhibiting the proliferation of spoilage microorganisms.

Potential surrogate plants for use in semi-field pesticide risk assessment with Megachile rotundata.

BACKGROUND: Current regulatory pesticide risk assessments for bees are based primarily on the honey bee (Apis mellifera) and may not always be protective of solitary bees. To incorporate solitary bees into the risk assessment process, standardized methods to assess the hazard of pesticides under semi-field (Tier II) conditions will be needed. We conducted a series of experiments over 2 years to assess potential surrogate plants and adult release rates for use in semi-field experiments with the alfalfa leafcutting bee (ALB, Megachile rotundata). METHODS: We compared ALB foraging activity and reproduction on 12 m2 plots of flowering alfalfa (Medicago sativa) and buckwheat (Fagopyrum esculentum) at low (10♀/20♂) and high (20♀/40♂) adult release rates. The following year, we assessed the same endpoints on plots of purple tansy (Phacelia tanacetifolia) at a release rate of 10♀/15♂. RESULTS: Although ALB foraging activity was high on buckwheat plots, fewer adults were produced compared to alfalfa plots. On alfalfa, there were no differences in foraging activity, nesting, or reproduction between the low and high release rates. ALB readily foraged from purple tansy flowers, but females avoided purple tansy leaves for leaf cell construction. DISCUSSION: Our study suggests that buckwheat alone cannot support ALB during semi-field studies on small plots. For alfalfa, we recommend a maximum release rate of 10♀/20♂ in 12 m2 plots. Further study of higher ALB release rates on purple tansy is warranted. A mixed planting of purple tansy and a plant suitable for leaf piece collection (e.g., buckwheat) may provide favorable conditions for ALB activity and reproduction during semi-field testing.

Comparison of Pesticide Exposure in Honey Bees (Hymenoptera: Apidae) and Bumble Bees (Hymenoptera: Apidae): Implications for Risk Assessments.

To date, regulatory pesticide risk assessments have relied on the honey bee (Apis mellifera L.) (Hymenoptera: Apidae) as a surrogate test species for estimating the risk of pesticide exposure to all bee species. However, honey bees and non-Apis bees may differ in their susceptibility and exposure to pesticides. In 2017, a workshop ('Pesticide Exposure Assessment Paradigm for Non-Apis Bees') was held to assess if honey bee risk assessment frameworks are reflective of non-Apis bee pesticide exposure. In this article, we summarize the workshop discussions on bumble bees (Bombus spp.). We review the life history and foraging behavior of bumble bees and honey bees and discuss how these traits may influence routes and levels of exposure for both taxa. Overall, the major pesticide exposure routes for bumble bees and honey bees are similar; however, bumble bees face additional exposure routes (direct exposure of foraging queens and exposure of larvae and adults to soil residues). Furthermore, bumble bees may receive comparatively higher pesticide doses via contact or oral exposure. We conclude that honey bee pesticide risk assessments may not always be protective of bumble bees, especially queens, in terms of exposure. Data needed to reliably quantify pesticide exposure for bumble bees (e.g., food consumption rates, soil residue levels) are lacking. Addressing these knowledge gaps will be crucial before bumble bee exposure can be incorporated into the pesticide risk assessment process. Because bumble bees exhibit appreciable interspecific variation in colony and behavioral characteristics, data relevant to pesticide exposure should be generated for multiple species.

The Impact of the Carrot Rust Fly and Carrot Weevil Integrated Pest Management Program on the Ground-Dwelling Beetle Complex in Commercial Carrot Fields at the Holland Marsh, Ontario, Canada.

Carrot rust fly (CRF), Psila rosae (Fabricius, 1794) (Psilidae: Diptera) and carrot weevil (CW), Listronotus oregonensis (Le Conte, 1857) (Curculionidae: Coleoptera) are economic pests of carrot; larval tunneling on roots results in direct damage rendering the carrot unmarketable. The Holland Marsh in Ontario, Canada, is a major carrot production area. The ground-dwelling beetle (Coleoptera) fauna in commercial carrot fields in this region has not been described. In 2015 and 2016, eight commercial carrot fields were surveyed using pitfall traps to determine abundance and diversity of the ground-dwelling beetle complex. Research sites, which were used to evaluate the effectiveness of an existing integrated pest management (IPM) program, were also surveyed to determine the impacts of the IPM program on the natural enemy diversity, compared to insecticide-free sites. In total, 50 taxa and 4,127 individual ground-dwelling beetles were identified over the course of the 2 y. Known natural enemies of CRF and CW were identified and recovered in abundance. The abundance and diversity of ground-dwelling beetles among the commercial carrot fields varied greatly in 2015 and 2016 but was similar on research sites sprayed according to the IPM program compared to insecticide-free sites in both years. The importance of this research to promote conservation biological control through the naturalization of nonagricultural areas is discussed.

Exposure to clothianidin seed-treated canola has no long-term impact on honey bees.

We conducted a long-term investigation to ascertain effects on honey bee, Apis mellifera L., colonies during and after exposure to flowering canola, Brassica napus variety Hyola 420, grown from clothianidin-treated seed. Colonies were placed in the middle of 1-ha clothianidin seed-treated or control canola fields for 3 wk during bloom, and thereafter they were moved to a fall apiary. There were four treated and four control fields, and four colonies per field, giving 32 colonies total. Bee mortality, worker longevity, and brood development were regularly assessed in each colony for 130 d from initial exposure to canola. Samples of honey, beeswax, pollen, and nectar were regularly collected for 130 d, and the samples were analyzed for clothianidin residues by using high-performance liquid chromatography with tandem mass spectrometry detection. Overall, no differences in bee mortality, worker longevity, or brood development occurred between control and treatment groups throughout the study. Weight gains of and honey yields from colonies in treated fields were not significantly different from those in control fields. Although clothianidin residues were detected in honey, nectar, and pollen from colonies in clothianidin-treated fields, maximum concentrations detected were 8- to 22-fold below the reported no observable adverse effects concentration. Clothianidin residues were not detected in any beeswax sample. Assessment of overwintered colonies in spring found no differences in those originally exposed to treated or control canola. The results show that honey bee colonies will, in the long-term, be unaffected by exposure to clothianidin seed-treated canola.

Effectiveness of Naturally Occurring Substances Added to Duck Litter in Reducing Emergence and Landing of Adult Musca domestica (Diptera: Muscidae).

Poultry barns provide an ideal breeding environment for Musca domestica L. (Diptera: Muscidae) owing to the controlled temperatures and litter (manure plus bedding material) accumulation. Management techniques that render the litter less suitable for immature stage development, such as the addition of naturally occurring insecticidal substances, could reduce fly infestations. The effectiveness of acetic, boric, and citric acids; diatomaceous earth; and hydrated lime at restricting female landing and growth of house flies in duck litter was evaluated. Litter treated with 1.9% and 4.7% by weight of acetic or boric acid had significantly lower adult emergence rates compared with the same concentrations of citric acid, diatomaceous earth, hydrated lime, or the untreated control litter. The pH of duck litter treated with acetic or citric acid was significantly reduced and remained significantly lower than the control litter (pH 8.7) for 10 d. Significantly more house flies landed on a house fly-rearing substrate (wheat bran, powdered milk, bloodmeal, water, and yeast) than litter treated with any of the other test substances or the control. The LC50 for boric acid was estimated to be 0.01% by weight, which was lower than that of acetic acid (1.42%). Similarly, the LC90 of boric acid was estimated to be 0.12%, which was lower than that of acetic acid (10.03%). Acetic acid and boric acid have the potential to be incorporated into litter as a pest management tactic to reduce house fly populations in duck production facilities.

Development of a mechanical sexing system to improve the efficacy of an area-wide sterile insect release programme to control American serpentine leafminer (Diptera: Agromyzidae) in Canadian ornamental greenhouses.

BACKGROUND: American serpentine leafminer (ASL), Liriomyza trifolii (Burgess), is a significant pest of greenhouse ornamental crops, and females damage leaf tissue with their ovipositor during feeding and oviposition. The sterile insect technique has been advocated as a non-chemical alternative to currently available control methods. In area-wide sterile insect release programmes, males act as true vectors of sterility. Females should be eliminated from a cohort of pupae prior to irradiation to maximise production economics and sterility spread. The aim of this research was to develop a mechanical sexing system based on pupal size to reduce the proportion of ASL females. RESULTS: Cumulative frequency distributions were used to examine significant differences in male and female pupal length and dorsal and lateral width distributions. Optimum size cut-off points based on the largest differences in distribution curves were used to determine the dimensions of three different sieve designs. Sieve pores measuring 1.543 mm by 0.765 mm excluded 76% of female pupae and doubled the proportion of males in the throughput sample. CONCLUSION: Pupal sexual dimorphisms identified in this research can be used to design a sieve to aid in reducing the proportion of females prior to irradiation, thus improving the efficacy of an area-wide sterile insect release programme. © 2016 Society of Chemical Industry.

Comparison of buckwheat, red clover, and purple tansy as potential surrogate plants for use in semi-field pesticide risk assessments with Bombus impatiens.

Background. Bumble bees (Bombus spp.) are important wild and managed pollinators. There is increased interest in incorporating data on bumble bees into risk assessments for pesticides, but standardized methods for assessing hazards of pesticides in semi-field and field settings have not yet been established for bumble bees. During semi-field studies, colonies are caged with pesticide-treated flowering surrogate plants, which must be attractive to foragers to ensure colony exposure to the test compound, and must produce an ample nectar and pollen to sustain colonies during testing. However, it is not known which plant(s) are suitable for use in semi-field studies with bumble bees. Materials and Methods. We compared B. impatiens foraging activity and colony development on small plots of flowering buckwheat (Fagopyrum esculentum, var. common), red clover (Trifolium pratense), and purple tansy (Phacelia tanacetifolia) under semi-field conditions to assess their suitability as surrogate plants for pesticide risk assessment studies with bumble bees. We also compared the growth characteristics and input requirements of each plant type. Results. All three plant types generally established and grew well. Red clover and purple tansy experienced significant weed pressure and/or insect pest damage. In contrast, pest pressure was extremely low in buckwheat. Overall, B. impatiens foraging activity was significantly greater on buckwheat plots than red clover or purple tansy, but plant type had no effect on number of individuals produced per colony or colony weight. Discussion. Because of the consistently high foraging activity and successful colony development observed on buckwheat plots, combined with its favourable growth characteristics and low maintenance requirements, we recommend buckwheat as a surrogate plant for use in semi-field pesticide toxicity assessments with B. impatiens.

The efficacy of spinosad against the western flower thrips, Frankliniella occidentalis, and its impact on associated biological control agents on greenhouse cucumbers in southern Ontario.

Insecticides are the most commonly used tactic to control western flower thrips (WFT), Frankliniella occidentalis Pergande (Thysanoptera: Thripidae), on greenhouse cucumber. However, WFT has developed resistance to several of the insecticides presently in use. In addition, some of these insecticides adversely affect greenhouse biological control agents used to control WFT, resulting in subsequent pest resurgence. Therefore, there is a need to identify novel insecticides with unique modes of action for use in integrated pest management (IPM) programs to effectively control WFT with minimal impact on associated biological control agents. In laboratory bioassays conducted in 2001, immature and adult WFT and three associated greenhouse biological control agents: Amblyseius cucumeris Oudemans (Acarina: Phytoseiidae), Orius insidiosus Say (Hemiptera: Anthocoridae) and Encarsia formosa Gahan (Hymenoptera: Aphelinidae) were exposed to direct, direct/residual, and residual contact applications of the novel biopesticide, spinosad (Conserve 120 SC), and the industry standard for whitefly control, endosulfan (Thiodan 50 WP). In all three types of assay, spinosad was effective against immature and adult WFT life stages. It showed low toxicity to A. cucumeris, moderate toxicity to O. insidiosus and high toxicity to E formosa. Greenhouse studies involving exposure of immature and adult WFT and adult biological control agents to cucumber leaves sprayed previously with spinosad supported the laboratory data. Spinosad showed low toxicity to A. cucumeris exposed to leaves 1 day after treatment (DAT), moderate toxicity to O. insidiosus 1 and 8 DAT, and high toxicity to E. formosa up to 28 DAT. These data, along with spinosad's unique mode of action, suggest it would be a valuable reduced-risk control agent for greenhouse cucumber IPM programs.