Do tephritid-induced fruit volatiles attract males of the fruit flies parasitoid Psyttalia concolor (Szepligeti) (Hymenoptera: Braconidae)?

The braconid wasp Psyttalia concolor (Sz,pligeti) is an endoparasitoid of several tephritids of economic importance. Even if it has been reported that females of this species rely extensively on tephritid-induced fruit volatiles (TIFVs) during host location, no information is available on the behavioural role of TIFVs on males. Because P. concolor females mate only once, we hypothesized that the perception of TIFVs could be crucial for males, guiding them towards infested fruits on which they could find newly emerged females, thus raising the males' chances to locate receptive females during their lifespan. On this basis, here we evaluate the attractiveness of synthetic TIFVs from two different trophic interactions, Ceratitis capitata-Malus domestica and Ceratitis capitata-Prunus persica towards P. concolor virgin males. The results showed that both fruit-mimicking blends, three synthetic apple-borne (1-butyl butyrate, 1-butyl hexanoate and 1-hexyl (E)-2-methylbutenoate) and four synthetic peach-borne (ethyl octanoate, nonanoic acid, decanoic acid and dodecanoic acid) compounds were found to attract males. Among these molecules, 1-butyl butyrate, 1-butyl hexanoate and decanoic acid also prolonged the time the males spent performing searching activities on the TIPV-treated surface. Because males probably use these volatiles mainly for sexual purposes, we believe that these chemicals could be classified as sexual kairomones.