Ladies first: the butterfly effect and plasticity of population growth in Drosophila suzukii

Spotted Wing Drosophila (SWD), Drosophila suzukii, is a major pest of small fruits including raspberries. In Minnesota, SWD presents with a sudden appearance of females followed by rapid population growth in late July and early August. This would indicate that early season sex ratios may be a major contributing factor to the exponential population growth. To evaluate the possible mechanisms that may be driving population growth of D. suzukii, a survey of season long population dynamics and sex ratios was conducted in Minnesota raspberry fields. Survey results show that fist trap catch occurred between June 5^th and July 16^th and that that the female populations were consistently higher than males during the first few weeks of activity. Moreover, where insecticide sprays occurred, female populations were higher than male populations for a majority of the season. This indicates that insecticide pressure may be affecting sex ratios or females may be less susceptible to insecticides. Future studies should focus on the sublethal effects of insecticides used to manage SWD, and how these effects influence early season sex ratios and later season population growth.