Philip D. Fanning

Since its detection in the continental United States in 2008, spotted-wing drosophila (Drosophila suzukii Matsumura) has become a significant pest of thin-skinned fruits. Current management strategies largely depend on calendar-based insecticide applications, which have disrupted previously established integrated pest management programs. Alternative control tactics, such as behavioral manipulation with phagostimulants, are being explored to reduce dependence on insecticides. In this study, we evaluated the effects of adding the commercial phagostimulant Combi-protec Insect Bait Attractant on the efficacy of insecticides targeting D. suzukii. The study was conducted across 6 US states (New Jersey, Georgia, Michigan, Oregon, Maine, and New York) under field conditions using highbush blueberries, lowbush blueberries, and raspberries. Treatments were applied in the field under caged conditions in 2021 and open conditions in 2022, followed by laboratory bioassays to assess adult mortality, oviposition, and larval infestation/emergence. When adults were exposed to freshly treated materials, insecticide treatments combined with Combi-protec generally performed as well as, or better than, insecticides alone in highbush blueberries (particularly spinetoram and phosmet); however, inconsistent results were observed in lowbush blueberries and raspberries. As materials aged in the field, efficacy across treatments declined, leading to variable results. Oviposition patterns closely mirrored adult mortality, but the treatment effects on developing larvae and emerged progeny were inconsistent or negligible. Overall, Combi-protec enhanced the efficacy of insecticides against adult D. suzukii, though its benefits for subsequent life stages were inconsistent. These findings provide new insights into the potential role of phagostimulants for improving insecticide effectiveness for D. suzukii control.

Numerous natural enemies have been investigated to suppress spotted-wing drosophila, Drosophila suzukii, a pest of small fruits and cherries. Current efforts include widespread releases of an imported figitid parasitoid, Ganaspis kimorum, conserving resident pupal parasitoids and an adventive figitid, Leptopilina japonica, and the application of entomopathogenic nematodes. However, the combined effectiveness of parasitoids and nematodes is relatively unknown. Five laboratory studies examined the combination of G. kimorum or L. japonica with the nematodes Steinernema carpocapsae or S. feltiae. The nematodes were applied to the substrate when wandering D. suzukii larvae were about to pupate. Results showed that the combination of parasitoids and nematodes led to higher pest suppression than either parasitoid or nematode only treatments, with an overall 56% to 83% reduction in D. suzukii emergence relative to the control. In 2 cases, the combination had similar effectiveness as the parasitoid-only treatment. The exposure of parasitized larvae to nematodes lowered parasitoid emergence by 26% to 68%. Two studies exposed pupae recently parasitized by the pupal parasitoids Pachycrepoideus vindemiae and Trichopria drosophilae to S. carpocapsae, and the exposure to nematodes lowered adult parasitoid emergence by 49% and 71%, respectively. Given the potential increase in overall pest control but negative impact on developing parasitoids, the decision to combine approaches may be based on whether the goal is to maximize biological control or to establish parasitoids.

Spotted-wing drosophila (SWD), Drosophila suzukii Matsumura (Diptera: Drosophilidae), is an invasive pest of thin-skinned fruits in the United States. Monitoring traps are an integral part of SWD integrated pest management, allowing early detection and timely management of this pest. An ideal monitoring trap should be easy to use, effective in capturing SWD, sensitive and selective to male SWD which are easy to identify due to their spotted wings, and able to predict fruit infestation from trap captures. Deli-cup-based liquid traps (grower standard), which make in-situ observations difficult, were compared with red-panel sticky traps, both baited with commercial lures (Scentry, Trécé Broad-Spectrum (BS), and Trécé High-Specificity (HS)), across several US states in blueberries (lowbush and highbush), blackberry, raspberry, and cherry crops during 2018 and 2021. Results showed that red-panel traps effectively captured SWD, were able to detect male SWD early in the season while also being selective to male SWD all season-long, and in some cases linearly related male SWD trap captures with fruit infestation. Scentry and Trécé BS lures captured similar numbers of SWD, though Trécé BS and Trécé HS were more selective for male SWD in red panel traps than liquid traps in some cases. In conclusion, due to its ease of use with less processing time, red-panel traps are promising tools for detecting and identifying male SWD in-situ and for predicting fruit infestation. However, further research is needed to refine the trap captures and fruit infestation relationship and elucidate the trap-lure interactions in berry and cherry crops.

The invasive spotted-wing drosophila, Drosophila suzukii (Matsumura), is a key insect pest of berries globally, causing lost revenues and increased production costs associated with applications of insecticides. The insecticides utilized are commonly broad-spectrum pyrethroids, organophosphates, or carbamates in conventionally managed fields and spinosad in organically managed fields. Adoption of more selective insecticides has been limited due to their lower residual activity, and the requirement that some must be ingested to be effective. We investigated the use of feeding stimulants for D. suzukii as a method to improve longevity and efficacy in a range of insecticides. In laboratory bioassays, sugar increased the efficacy of all chemical classes tested; however, the inclusion of yeast only showed a benefit with malathion. Feeding stimulants had a limited effect in some cases under field conditions. Similarly, infestation in field plots and a semifield bioassay showed no significant decreases in infestation with the inclusion of feeding stimulants for the insecticides tested in these trials. We discuss the implications of these findings for managing D. suzukii in fruit crops to help ensure the harvest of marketable fruit.

The spotted wing drosophila, Drosophila suzukii Matsumura, is an invasive pest of many fruit crops throughout North America, South America and Europe. The presence of this destructive pest has led to an increase in the number of insecticide applications. While conventional growers have an arsenal of different insecticides at their disposal, organic growers have a limited selection of effective options and rely heavily on applications of Entrust^®, the organic formulation of spinosad. An important part of research is to develop more tools for organic growers and evaluate the effects of insecticides intended to target D. suzukii on natural enemies in the system. The effects of six organic pesticides alone and in combination with three adjuvants and two phagostimulants were tested in laboratory bioassays on three common natural enemies in berry production systems including two predators, Chrysoperla rufilabris and Orius insidiosus, and a parasitoid wasp, Aphidius colemani. Under the IOBC toxicity rating scale, spinosad was rated consistently from slightly harmful to harmful across natural enemy species and residue age (the effects of pesticides over time). Sabadilla alkaloids caused mortality to O. insidiosus equal to that of spinosad. All tested pesticides were at least slightly harmful to A. colemani, and the adjuvant polyether‐polymethylsiloxane‐copolymer polyether caused mortality that was not significantly different from spinosad. In general, neither the addition of adjuvants nor phagostimulants increased the mortality of the insecticides tested. The exception was polyether‐polymethylsiloxane‐copolymer polyether, but it is unclear whether it increased the toxicity of the pesticides or was simply toxic itself since it caused high mortality to A. colemani when applied alone. Sublethal effects were measured for two predatory species by measuring eggs laid and % egg hatch. Minimal sublethal effects were observed in C. rufilabris. In contrast, all tested insecticides caused reduced egg hatch in O. insidiosus compared with the control.