Developing heterospecific Sterile Insect Technique for pest control: insights from the spotted wing fly Drosophila suzukii

BACKGROUNDReproductive interference (i.e., sexual interaction between males of one species and females of another species that reduce the fitness of one or both the interacting individuals) is an important species interaction significantly affecting population dynamics and persistence. However, its exploitation in pest control remains overlooked. Here, we investigated the possible integration of reproductive interference into the Sterile Insect Technique (SIT) to develop a heterospecific SIT (h-SIT). Under this approach, contrary to the classic SIT, sterile heterospecific males from closely related, non-pest species are released to compete with the pest population for mates. At this aim, we focused on the invasive pest species Drosophila suzukii and used D. melanogaster as the control species. First, we investigated the effect of irradiation on D. melanogaster sterility and longevity. Then, we tested the mating performance of irradiated males and their ability to reduce the D. suzukii fitness. RESULTSWe found by microcosm experiments that: i) irradiation induced high levels of D. melanogaster male sterility without reducing longevity; ii) irradiated D. melanogaster males court D. suzukii females as much as D. suzukii males and they couple, mate and fecund heterospecific females; iii) irradiated D. melanogaster males significantly reduce the offspring of D. suzukii females under two different species ratios. CONCLUSIONSOur results provide the first foundation to develop a heterospecific Sterile Insect Technique against D. suzukii and fuel to test this approach against other groups of pest species.