Evaluation of Food-Based Attractants for Drosophila suzukii (Diptera: Drosophilidae).

The Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) is a highly invasive species attacking a wide range of ripening soft-skinned fruits. A series of laboratory choice tests were conducted to determine whether different levels of rice vinegar affected attraction of Merlot wine to D. suzukii, as well as to compare attractiveness of two common fermentation food baits: wine-vinegar and yeast-sugar water mixtures. The relative attraction of various combinations was used to develop a bait whose effectiveness was tested in the field. In laboratory choice experiments, wine-vinegar (80:20, v:v, hereafter referred to as wine) was more preferred over a yeast-sugar water mixture (hereafter referred to as yeast) by D. suzukii. Combination baits, either a mixture of wine and yeast or a mixture of wine and a supernatant from the yeast (comboS), were significantly more attractive than each product alone. The two combination baits were equally attractive to D. suzukii, so were the yeast and its supernatant, suggesting that yeast supernatant could be used as a replacement for the yeast-sugar mixture currently used for trapping D. suzukii. The additive effect between wine and yeast supernatant in the field was not as profound as observed in the laboratory. In the field trial, numerically more male and female D. suzukii were captured in traps baited with comboS than those baited with the wine or yeast alone; however, significant differences were only found between the comboS and wine or between the comboS and yeast in some weeks over the period of the experiment.