Optimizing the attractiveness of diluted Concord grape juice: An effective, low-cost attractant for Drosophila suzukii (Diptera: Drosophilidae)

Recent research has focused on the evaluation of fruit-based materials as source of attractants for spotted-wing Drosophila, Drosophila suzukii (Diptera: Drosophilidae), a fruit fly native to southeast Asia and invasive to North America. Previously, our lab reported on the high attractiveness of diluted Concord grape juice, a low-cost and readily available material, to male and female D. suzukii. When diluted at a ratio of 1 part of grape juice and three parts of water, grape juice showed to be more attractive to males and females than some commercial lures under field conditions. Grape juice diluted at the 1:3 ratio (= DGJ) also attracted significantly fewer (about three times less) non-targets than some commercial lures, highlighting the greater selectivity of grape juice. Here, we investigated the effects of fermentation and the addition of some household materials on DGJ. DGJ that was aged for 1 and 2 weeks was significantly more attractive to adult D. suzukii, in particular females. Our results indicate that DGJ can be deployed in traps and remain attractive to adult D. suzukii for at least 2 weeks.