Volatiles from Botrytis cinerea-infected and healthy berries of Vitis vinifera influence the oviposition behaviour of Epiphyas postvittana

Interactions among plants, plant-feeding insects, and plant-pathogenic fungi are partially mediated by volatile compounds. Herbivorous insects use sensory cues to choose host plants for feeding and/or oviposition that are likely to support survival and development of progeny. It is known that some fungus-induced alterations in plants can modify plant volatiles, which are recognized by the olfactory receptors of the insect, either as an attractant or as a deterrent. We tested for the presence of behaviour-modifying volatiles emanating from the berries of Vitis vinifera L. (Vitaceae) infected with Botrytis cinerea Pers. (Helotiales). We tested the olfactory behaviour of adults of Epiphyas postvittana Walker (Lepidoptera: Tortricidae) to these volatiles using two-choice and wind-tunnel experiments. We hypothesized that olfactory cues influence E. postvittana's oviposition behaviour. We found that volatiles emanating from B. cinerea-infected berries did not significantly attract the gravid females of E. postvittana; consequently, they laid significantly fewer eggs on infected berries. Furthermore, significantly fewer females of E. postvittana were found attracted to infected berries in the wind tunnel assay. Ethanol and 3-methyl-1-butanol were abundant in B. cinerea-infected berries. Oviposition assays made with laboratory standards of ethanol and 3-methyl-1-butanol confirmed their role in regulating the olfactory behaviour of E. postvittana site selection.