BEHAVIORAL AND PHYSIOLOGICAL-RESPONSES OF DIAERETIELLA-RAPAE TO SEMIOCHEMICALS

Diaeretiella rapae (M'Intosh) (Hymenoptera: Braconidae) parasitizes ma ny aphid species, including cabbage aphids on cruciferous crops and Ru ssian wheat aphids on cereal crops. We investigated the olfactory perc eption of D. rapae to semiochemicals that may be encountered in these two environments while searching for hosts or for mates. We conducted electroantennogram and flight-tunnel experiments on male and female D. rapae and found marked differences between sexes. Cruciferous volatil es elicited physiological and behavioral responses by females but not by males. Males and females responded similarly to (Z)-3-hexen-1-ol, a component of green-leaf volatiles, in both electroantennogram and fli ght-tunnel assays. Female wasps responded similarly regardless of prio r oviposition experience or population origin. Likewise, mating histor y and aphid presence did not increase responsiveness toward these semi ochemicals.