Identification of Mythmna separata-induced maize volatile synomones that attract the parasitoid Campoletis chlorideae

Campoletis chlorideae Uchida (Hym., Ichneumonidae) is an important solitary koinobiont larval endoparasitoid of many noctuid species including Mythmna separata (Lep., Noctuidae). In the present study, maize volatiles induced by feeding damage of M. separata were found to be attractive to C. chlorideae in a Y-tube olfactometer. Eleven compounds were released in significant amounts from M. separata-infested maize seedlings, of which five compounds, (Z)-3-hexen-1-ol, (Z)-3-hexenyl acetate, (E)-2-hexenal, linalool and phenylethyl acetate were chosen for electrophysiological and behavioural tests. All five compounds elicited electroantennogram responses in C. chlorideae. However, only pure (Z)-3-hexenyl acetate and linalool were attractive to the parasitoid in the Y-tube. Interestingly, linalool was also attractive to starved parasitoids over a range of doses tested. These results suggested that (Z)-3-hexenyl acetate and linalool may be key infochemicals in the host-foraging behaviour of C. chlorideae, and linalool may act as a food-source signal for the parasitoid.