The Japanese beetle, Popillia japonica, is native to East Asia and was accidentally introduced into Northern Italy, from where it quickly spread to southern Switzerland. It is now also found north of the Alps. The beetle is highly polyphagous, feeding on commercially important plants like fruits trees, grapevine, and vegetable crops. As eradication attempts against this priority quarantine pest have failed, long-term management options need to be developed, which provide effective area-wide control. Classical biological control (CBC) using the parasitoid Istocheta aldrichi is a promising approach, but some biosafety aspects of the agent still need to be clarified. Further, CBC is not likely to solve the problem alone and thus, its suitability in the context of an Integrated Pest Management (IPM) program needs to be studied.

Together with our project partner CABI

1. We assess if parasitoids of native beetles adopt the Japanese beetle as host by collecting and rearing beetle grubs and adults;
2. study aspects of ecological risks that the introduction of I. aldrichi in Switzerland could pose, notably by conducting choice tests with non-target beetles;
3. investigate the compatibility of CBC with other control methods in a series of tests including pheromones, entomopathogenic fungi, nematodes, and kaolin.

The proposed project will identify potential synergies between CBC and other management methods and will help to optimize IPM against the Japanese beetle to achieve the best possible control.