Sustainable control of Drosophila suzukii in cherries, strawberries and ligneous small fruits

The Asiatic fruit fly Drosophila suzukii or “spotted wing Drosophila (SWD)” in short time became the most damaging insect pest of cherries, strawberries and small fruits in Europe. In Belgium first damage was noticed in 2011, and year after year SWD multiplied further and spread over all fruit growing regions in Belgium.

Incapacity of chemical crop protection products to control D. suzukii

Concerning spraying applications with chemical crop protection products, it turned out that only broad active compounds (pyrethroids, spinosyns, organophosphates) have a sufficient fast control activity against D. suzukii. However, the (multiple) applications with this type of insecticides are detrimental for integrated control of (other) pests, as all beneficial insects and mites are killed. Therefore we focus in this project on control measures compatible with biological control for a sustainable control of D. suzukii.

Knowledge is power in the battle against D. suzukii

Firstly we collected lots of valuable knowledge concerning key aspects of biology of D. suzukii in our fruit growing conditions. We were able to determine that SWD has 7 generations in Flanders, and that they overwinter as adults in protected habitats, preferentially in woody (bush) structures. Furthermore ripening cherries were found to be the first important host plant in the season. From the very first colouration (or ripening) host fruits are susceptible for infestation. We also noticed big differences in behaviour between summer and winter SWD morphs.

Mass trapping and Attract & Kill

The “attract and kill” and “mass trapping” strategies in which pest insects are attracted to a trap and killed are interesting control alternatives for organic fruit growing. They allow to monitor and control D. suzukii without massively spraying chemical insecticides. Based on the gained insights into the biology of SWD we are currently developing and testing these strategies in field trials. The outcomes of these trials will determine the efficacy of these biological control strategies against SWD in fruit growing in Flanders.

Sanitary control measures during and after harvest

Crop hygiene and fruit waste disposal are very important to prevent further multiplication and spreading of SWD in fruit farms. In this project we also developed a practical fruit waste container in which SWD is killed quickly and effectively. Furthermore the fruit waste is transformed to a valuable fertilizer for other (fruit) crops.