Comparative morphology and evolutionary genomics provide useful clues for management of an emerging Drosophila pest

Drosophila suzukii is one of the few fruit flies to lay eggs and feed on fresh fruit. Its recent outbreak in western countries, and its peculiar ecological behaviour makes it an emerging model for pest management and biology. A recent genomic survey suggested that D. suzukii unusual behaviour is intimately linked with an ecological pre-adaptions to temperate climates and the ability of overwinter in sexual diapause state. Here we provide comparative morphological and behavioural evidences supporting that diapause occurs preferentially in females, is temperature dependent, and is likely mediated by an enlargeable highly pigmented spermatecha. Comparative genomics reveals that a cytochrome associated with spermatecha is differentially expressed and the gene under stronger positive selection in D. suzukii compared to sister species. Based on these results, we advocate that an early spring trapping is key for D. suzukii population control as it may target the few overwintering females exiting diapause. Evolutionary genomics further identifies two genes under positive or abnormal evolution involved in insecticide resistance and immune response to parasitoids, warning us on the feasibility of some types of control strategies. Our results show that evolutionary genomics and comparative morphology are useful tools to guide application in the field of pest management