Volatile cues from Corcyra cephalonica larva elicit behavioural responses in parasitoid, Habrobracon hebetor

The rice moth, Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae), is a serious pest of grains in storage systems resulting in immense losses but is also widely used as a factitious host for mass rearing of many important natural enemies of crop pests. Given the role of kairomones, the aim of this study was to isolate and identify potential cues from the larval body wash of C. cephalonica, which could attract its gregarious ectoparasitoid, Habrobracon hebetor (Say) (Hymenoptera: Braconidae). Gas chromatography with electroantennography (GC-EAG) and olfactory assays were used to demonstrate the attraction of female H. hebetor to different larval body volatiles. A total of 15 EAG-active compounds were discovered in the body wash of C. cephalonica larvae that triggered a response in female H. hebetor. Among them, four compounds (p-xylene, naphthalene, n-eicosane and n-tricosane) were bioassayed for the behavioural response of parasitoids and found that n-eicosane significantly attracted a higher number of parasitoids than others. Our work establishes the attraction of H. hebetor to volatile kairomone cues emanating from the factitious host larval body, which offers an opportunity for its parasitoid, H. hebetor to improve the mass rearing efficiency.