Evaluation of predatory activity of Orius laevigatus (Fieber) and O. maiusculus Reuter towatds Drosophila suzikii (Matsumura) under laboratory conditions

Drosophila suzukii (Matsumura) (Diptera Drosophilidae) is a highly poliphagous insect which is native to South East Asia and now is widespread in many regions of Europe causing severe damages to crops mainly soft fruits. As economic losses due to D. suzukii damages are relevant many efforts should be done to find strategies to control this pest. There are multiple biocontrol agents (fungi, bacteria, viruses and other natural enemies of the pest, such as predators and parasitoids) that could be employed in IPM for D. suzukii. Natural enemies in the invaded area may establish new associations with invasive pests, thus gradually contributing to its control. There is hence a high probability for natural enemies in the invaded regions to exploit also D. suzukii. The predatory activity of Anthocorids was suggested by some Authors. The aim of this study was to test the predatory activity against D. suzukii of two specie of Anthocorids such as Orius laevigatus (Fieber) and O. maiusculus (Reuter), under laboratory conditions. D. suzukii females and males from FEM rearing were put into plastic box containing blueberries, and let lay eggs for 24-48 hours. After this period D. suzukii individuals were removed and the eggs laid in each blueberry fruit were counted. Blueberries infested by D. suzukii eggs were exposed to 0, 1, 2, 3 adult stages of O. maiusculus or O. laevigatus. A treatment containing blueberries without D. suzukii eggs and 3 Orius was also considered as control for the surviving of Orius. The number of emerged D. suzukii was checked daily until no more D. suzukii was born for three consecutive days. This number was compared with the initial egg counts to assess the predation of Orius on D. suzukii. The longevity of Orius was also considered. The experiments was carried out in a climatic chamber at22°C, U.R: 70% L:D 16:8. The results obtained in this trial showed a slightly predatory activity of O. maiusculus and an increase of its longevity, but no significant differences were observed among treatments. No predatory activity was observed for O. laevigatus. Data obtained in this study suggested a marginal role of O. laevigatus and O. maiusculus in controlling D. suzukii