Monitoring of Spotted-Wing Drosophila (Diptera: Drosophilidae) Resistance Status Using a RAPID Method for Assessing Insecticide Sensitivity Across the United States

Abstract

Drosophila suzukii (Matsumura) has spread rapidly, challenging berry and cherry crop production due to its ability to lay eggs into ripening fruit. To prevent infestation by this pest, insecticides are applied during fruit ripening and harvest. We field-tested the Rapid Assessment Protocol for IDentification of resistance in D. suzukii (RAPID) on seventy-eight populations collected across eight U.S. states in 2017 and 2018. Exposure to LC50 rates of malathion, methomyl, spinetoram, spinosad, and zeta-cypermethrin led to average female fly mortality of 25.0% in 2017, and after adjusting concentrations the average was 39.9% in 2018. Using LC99 × 2 discriminating concentrations in 2017 and LC90 × 8 rates in 2018, average female mortalities were 93.3% and 98.5%, respectively, indicating high overall susceptibility. However, using these high concentrations we found 32.0% of assays with survival of some female flies in 2017 and 27.8% in 2018. The adjustment in discriminating dose from 2017 to 2018 also reduced the proportion of assays with <90% survival from 17.6 to 2.9%. Populations with low mortality when exposed to spinosad were identified using this assay, triggering more detailed follow-up bioassays that identified resistant populations collected in California coastal region berry crops. Widespread evaluations of this method and subsequent validation in California, Michigan, and Georgia in 2019–2021 show that it provides a quick and low-cost method to identify populations of D. suzukii that warrant more detailed testing. Our results also provide evidence that important insecticide classes remain effective in most U.S. regions of fruit production.

Propensity for resistance development in the invasive berry pest, spotted‐wing drosophila (Drosophila suzukii), under laboratory selection

“…While our data suggest that field populations of D. suzukii are capable of developing resistance to some insecticides in rather short periods of time, much more work is needed to better understand the genetic factors related to insecticide resistance in D. suzukii , as well as the distribution of resistance alleles in field populations. Laboratory selection studies and resistance monitoring will be key in this pursuit 19 …”

“… 7 As such, these data will expand our knowledge about the threat of resistance to additional chemistries. This is also the first study to assess resistance in a Minnesota D. suzukii population that, when compared to field populations in other studies, 19 will allow for broader comparisons between fly populations in different regions. Overall, this work will contribute useful information that can improve our ability to make predictions about resistance development in D. suzukii and inform current management strategies to maintain the integrity of current chemical controls and slow the development of resistance.…”

Fly responses to food colour, orientation and toxic bait composition in Drosophila suzukii

“…Drosophila suzukii (Diptera: Drosophilidae), the spotted wing drosophila, is a devastating invasive agricultural pest of various fruit crops, including cherries, strawberries, raspberries and numerous others in Asia, Europe and the Americas (Little et al., 2020; Tait et al., 2021). Current control methods rely heavily on the application of synthetic insecticides, which can result in increased production costs, elevated pesticide residues in fruit produce and an increased risk of pest resistance (Isaacs et al., 2022; Shawer, 2020). Modern integrated pest management practices focus on the use of trap technologies for pest population monitoring (Burrack et al., 2020; Lasa et al., 2017; Lee et al., 2013), physical barriers (netting) to exclude adult flies (Kuesel & Gonthier, 2020), cultural control practices (Liburd & Rhodes, 2020; Schöneberg et al., 2021) and the use of selective biorational compounds and organic‐approved compounds that conserve insect natural enemy populations and contribute to pest control (Lisi et al., 2022; Sial et al., 2019).…”

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Drosophila suzukii (Diptera: Drosophilidae), the spotted wing drosophila, is a devastating invasive agricultural pest of various fruit crops, including cherries, strawberries, raspberries and numerous others in Asia, Europe and the Americas (Little et al, 2020;Tait et al, 2021). Current control methods rely heavily on the application of synthetic insecticides, which can result in increased production costs, elevated pesticide residues in fruit produce and an increased risk of pest resistance (Isaacs et al, 2022;Shawer, 2020). Modern integrated pest management practices focus on the use of trap technologies for pest population monitoring (Burrack et al, 2020;

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