Transcriptome analysis ofDrosophila suzukiireveals molecular mechanisms conferring pyrethroid and spinosad resistance

Abstract

AbstractDrosophila suzukiilay eggs in soft-skinned, ripening fruits, making this insect a serious threat to berry production. Since its 2008 introduction into North America, growers have used insecticides, such as pyrethroids and spinosads, as the primary approach forD. suzukiimanagement, resulting in detections of insecticide resistance in this pest. This study sought to identify the molecular mechanisms conferring insecticide resistance in these populations. We sequenced the transcriptomes of two pyrethroid- and two spinosad-resistant isofemale lines. In both pyrethroid-resistant lines and one spinosad-resistant line, we identified overexpression of metabolic genes that are implicated in resistance in other insect pests. In the other spinosad-resistant line, we observed an overexpression of cuticular genes that have been linked to resistance. Our findings enabled the development of molecular diagnostics that we used to confirm persistence of insecticide resistance in California, U.S.A. To validate these findings, we leveragedD. melanogastermutants with reduced expression of metabolic or cuticular genes that were found to be upregulated in resistantD. suzukiito demonstrate that these genes are involved in promoting resistance. This study is the first to characterize the molecular mechanisms of insecticide resistance inD. suzukiiand provides insights into how current management practices can be optimized.