Management strategies against Drosophila suzukii: insights into Swiss grape growers choices.

Background: In 2017, we investigated measures adopted by Swiss grape growers in response to Drosophila suzukii by conducting a survey presenting information obtained from 372 growers on 1708 vineyards.

Results: We found the strategies adopted to be heterogeneous and largely dependent on grape variety (table vs. wine grapes). We identified six clusters of control methods to combat D. suzukii, the most important of which involves using a combination of control methods such as insecticides, mass trapping and sanitation measures, especially pinching of foliage or mowing and mulching. Grape growers in our sample rely primarily on information from public institutions or other growers and the majority plan to continue taking sanitation measures to combat D. suzukii.

Conclusion: Our results suggest that strategies adopted in Switzerland differ widely, not only between growers, but also at a vineyard and regional level. Thus, policies and extension services should be targeted (e.g. to varieties and regions) and tailored to types of growers. We find that preventive measures are important when combatting D. suzukii and can reduce post-infestation measures such as pesticide usage. In our sample, biological insecticides, such as kaolin, played a vital role in the control of D. suzukii and merit further support. © 2019 Society of Chemical Industry.