Abstract

Drosophila suzukii is a polyphagous pest that causes economic losses to soft and stone fruit crops. Drosophila are generally attracted to metabolic volatiles produced by fruit associated yeast but to date only volatiles produced by yeasts separately have been tested for Drosophila attractiveness; however, the ecological reality is that fruits harbour many different yeasts. Using fully replicated two-way laboratory choice and field trapping experiments, volatiles from separate and combined yeast species were tested for attraction to D. suzukii. Four of 12 yeast species grown separately in strawberry juice were attractive in laboratory tests (P ranges 0.001-0.04) and two of these (Metschnikowia pulcherrima, Hanseniaspora uvarum) were also separately attractive to D. suzukii in the field. Four out of 10 combinations involving volatile profiles produced by Candida zemplinina, Pichia pijperi, M. pulcherrima and H. uvarum yeasts were attractive in the laboratory (P ranges 0.001-0.01). While combinations of M. pulcherrima + H. uvarum yeasts trapped the greatest numbers of D. suzukii in the field, the statistical support for the efficacy of this combination to trap greater numbers than sterile fruit juice is not strong and further, there was no significant difference in numbers trapped between separate H. uvarum and M. pulcherrima + H. uvarum combinations. While volatiles from isolates of M. pulcherrima and H. uvarum, both alone and combined, show some promise, further analyses is needed to ascertain the value of yeast combinations for D. suzukii baits.