D3202: Measuring the effects of organic insecticides used to manage Drosophila suzukii on Ganaspis brasiliensis mortality and offspring survival

Drosophila suzukii (Matsumura) is a significant pest for blueberry growers in North Central Florida. These pests are responsible for an estimated $1 billion dollars in economic losses annually, and if left un-managed, infestations can reduce a grower’s marketable fruit yield by as much as 80%. Managing these pests in conventional blueberry production is achieved with insecticides; however, managing these pests in organic systems is limited to cultural tactics and few organically certified insecticides. After the crop season ends, D. suzukii populations continue to persist in non-crop natural areas adjacent to the blueberry field by exploiting host fruits, which are available throughout most of the year. Recently, Ganaspis brasiliensis, a specialist parasitoid wasp, was approved for release in organic blueberry agricultural systems in Florida. If established, this parasitoid has the potential to reduce pest pressure in blueberry crop production year-round. Understanding the interaction between G. brasiliensis to insecticides can support decisions about when to release these parasitoids. Here, we exposed G. brasiliensis to three organically certified insecticides (Entrust (spinosad), Grandevo, and PyGanic) and observe mortality and offspring survival, and compared two bioassays (plant dipping, insecticide residue). Understanding how these parasitoids respond to insecticides and bioassay techniques will provide pest managers with important information about how to establish these beneficial insects.