Field Testing of 2-Pentylfuran as a Behavioural Control Tool for Spotted-Wing Drosophila in Raspberries

Spotted-wing drosophila (SWD), Drosophila suzukii, is a major pest of various soft-skinned fruit crops worldwide. We investigated an alternative approach to traditional insecticides to manage SWD. Previously, we have shown that 2-pentylfuran (2pf) reduced oviposition in raspberries in laboratory and small-scale field studies. Here, we further investigated the potential of 2pf as a management tool for SWD under more realistic field conditions. We tested the efficacy of 2pf under open field conditions in 2019 and 2020 using isolated plots of raspberries. For the two 2019 field trials, we used single raspberry fruiting inflorescences and deployed 2pf using a sachet for 48 h and 6 days, respectively, and assessed SWD infestation. We did not find any significant differences in SWD infestation in the 48 h trial but found noticeable reductions when 2pf was deployed for 6 days. In 2020, we randomly assigned treatments to an entire small, research planting of raspberries with different doses of 2pf (low, medium, and high) for both the summer and fall crops and recorded infestations. The low and medium doses of 2pf resulted in significant reductions in SWD infestation in field plantings when SWD densities were low (summer crop), but only the high dose reduced infestations when SWD pressure was high in the fall crop. Our study shows that 2pf has potential as a management tool for SWD under field conditions using a highly susceptible crop, but its effectiveness may vary depending on 2pf release rates and SWD abundance. Future studies are needed to test 2pf in combination with other repellents or with targeted insecticides.