Effect of macroarthropods on Drosophila suzukii peri-oviposition events: an experimental screening

Spotted wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), is an invasive pest which causes important damage to fruit crops, in particular in strawberry and cherry fields in Europe and North America. So far, its interaction with local fauna remains poorly studied, whereas it could give insight in the possibilities of biological control by using local predators. Indeed, no sustainable means of controlling populations of this fruit fly have been found, and alternative methods of pest management are needed. Here we compared the efficiency of 16 selected macroarthropods present in strawberry and cherry fields and farm structures from northern France. Most of them have never been tested against D. suzukii for their ability to disrupt its egg-laying behavior and/or to prey upon it under experimental conditions. A set of 17 morphological and behavioral traits potentially associated with the predation success of macroarthropods was measured. We counted nearly 16 000 eggs laid by female D. suzukii on artificial substrate in 1 008 experimental arenas. We observed an egg difference ranging from +65 to -98% in the presence of an arthropod, compared to control arenas (without arthropods), with an overall mean decrease of 44%. Some macroarthropod predatory species, mostly spiders (from the families Agelenidae, Salticidae, and Lycosidae) and the centipede Lithobius forficatus (L.), were efficient at killing the flies before they could lay eggs. Other species, such as the carabids Limodromus assimilis (Pontoppidan) and Poecilus cupreus (L.), or the woodlouse Porcellio scaber (Latreille), reduced egg-laying despite a lower predation rate. The macroarthopods' traits mainly involved in predation and disruption of oviposition were the size of their body and their mobility. Our results add novel information about the acceptability of D. suzukii as prey for common macroarthropods of the local fauna. This experimental approach provides a first pre-selection of promising macroarthropods that could be interesting in the control of D. suzukii populations.