Comparative response of two seasonal spotted wing drosophila (Drosophila suzukii) morphs to different classes of insecticides

Abstract

Drosophila suzukii Matsumura (Drosophilidae) is a devasting invasive pest affecting berry crops and cherry production throughout North America, South America, and Europe. This species has two different morph phenotypes, winter and summer morphs, which are temperature dependent. Chemical control is the most widely used management approach for managing the spotted wing drosophila, D. suzukii. Little is known regarding the differential response of the two seasonal morphs to insecticides. In this study, we identified a high number of differentially expressed genes likely involved in phase I, II, and III of detoxification pathways and other cuticular proteins in winter morphs as compared to summer morphs. Specifically, several detoxification genes (phase I: Cyp4e3, Cyp4s3, Cyp6d5, Cyp49a1, Cyp318a1; phase II: GstD10, Ugt35Bb, Ugt37b1, Ugt58Fa; phase III: Mdr65) were overexpressed more than two‐fold in winter morph. Additionally, we determined the median lethal concentration, LC50, values of Malathion, Cyantraniliprole, Imidan, Zeta‐cypermethrin, and Spinetoram insecticides to compare the insecticide susceptibility against two seasonal morphs of D. suzukii. For most of the pesticides tested, there were no differences between the LC50 values, between summer and winter morphs, however, we found that winter morph exhibited an LC50 value of Spinetoram 3.7‐fold, significantly higher than that of the summer morph. Overall, we demonstrated that seasonally induced different morphological phenotypes may result in different transcriptional response of phases I, II, and III of the detoxification pathways and other cuticular proteins. However, we found different responses to at least one insecticide, Spinetoram. It remains to be determined what are underlying physiological differences that lead to these changes in response to Spinetoram.

Winter Is (Not) Coming: Is Climate Change Helping Drosophila suzukii Overwintering?

“…The identification of these physiological changes that allow the survival of D. suzukii at colder temperatures is of the utmost importance not only to understand the thermal plasticity of this species, but also to develop SWD-focused management strategies. In fact, differences in the effect of insecticides between SM and WM have been suggested, especially Spinetoram, with WM appearing to be less susceptible than SM [54]. Additionally, monitoring traps are less efficient during the winter, which could be associated with differences in the response to volatiles between SM and WM [55].…”

Does the seasonal phenotype of Drosophila suzukii influence cellular immunity and parasitisation?

“…Adults of the winter phenotype have a longer lifespan at lower temperatures, have larger and darker bodies (Shearer et al., 2016; Wallingford & Loeb, 2016) and enter a temperature‐dependent reproductive diapause (Rossi‐Stacconi et al., 2016; Toxopeus et al., 2016; Zerulla et al., 2015). Furthermore, comparisons of the two phenotypes showed that the winter phenotype has an overexpression of detoxification genes in response to insecticides (Seong et al., 2022) and the summer morphs have a higher attraction to food odours (Schwanitz et al., 2022). The winter phenotype is adapted to colder conditions and is, therefore, the dominant phenotype at lower temperatures.…”