From a non-target to a target: identification of a fermentation volatile blend attractive to Zaprionus indianus

The African fig fly, Zaprionus indianus Gupta, is rapidly spreading through the New World and is a new potential pest for numerous fruit crops. Methods are needed to detect and monitor Z.indianus. A recent study shows that Z.indianus can be attracted with a mixture of wine and vinegar, but there are no chemical attractants yet identified. This fly was captured incidentally as a non-target insect in experiments to develop chemical lures, based on wine and vinegar fermentation volatiles, for Drosophila suzukii Matsumura and Drosophilamelanogaster Meigen. We then generated testable hypotheses on what combination of these volatiles was involved in Z.indianus attraction to wine and vinegar. We determined through a series of trapping experiments that the blend of ethanol, acetic acid, acetoin, isoamyl acetate, methionol and ethyl hexanoate constitutes a strong attractant for Z.indianus and accounts for its attraction to the combination of wine and vinegar. These results and findings provide the first opportunity to develop a long-lasting and consistent chemical lure for trapping of Z.indianus. Such a lure in a suitable trap should provide a good means to document the spread of the fly and determine its seasonality and abundance in new areas and crops.