Genetic basis of interspecies oviposition deterrents impacting the horticultural pest, Drosophila suzukii.

Organisms across all domains of life engage in interspecies communication to enhance their reproductive fitness. Genetic approaches to identify relevant signalling and response pathways have had success in microbes and plants and increasingly in insects. The proposed project will take advantage of the powerful genetic tools available in Drosophila fruit flies to identify the molecular pathways underlying interspecies signals that act as oviposition deterrents to the pest species, Drosophila suzukii. D. suzukii is an invasive pest that poses a threat to UK soft and stone fruit horticulture. Unlike endemic fruit flies such as D. melanogaster, D. suzukii oviposits in ripening fruit. Given increased regulation of and resistance to insecticide controls it is important to develop integrated pest management strategies for D. suzukii control. One promising avenue of investigation is indicated by a recent study documenting deterrence of D. suzukii oviposition by prior exposure of oviposition substrates to D. melanogaster (Shaw et al., Pest Manag Sci, 2018). It is the aim of this project to genetically define the responsible interspecies signals to inform strategies for managing D. suzukii oviposition. The student will examine genetic determinants of the D. melanogaster signal. This will be done by comparing the efficiency of D. suzukii oviposition deterrence using different D. melanogaster genotypes including mutants impacting relevant developmental (ovaries, oenocytes) and biosynthetic pathways (pheromones, cuticular hydrocarbons, sex peptide). In parallel, the sensory nature of the signal will be evaluated using genetic manipulations of D. suzukii using both pre-existing (Karageorgi et al., Curr Biol, 2017) and new genetic tools. Genetic differences identified on artificial oviposition substrates will be verified using fruit in both lab and semi-field settings.