Olfactory response of Habrobracon hebetor (Hymenoptera: Braconidae) to Helicoverpa armigera and its two host plants

Abstract

The volatiles emitted by herbivorous insects and herbivore-damaged plants play an important role in foraging behaviour of parasitoids that lead to host location of parasitic wasps. The olfactory response of Habrobracon hebetor (Say) (Hymenoptera: Braconidae) to volatile compounds of larvae and larval faeces of Helicoverpa armigera (Hünber) (Lepidoptera: Noctuidae), corn ear and tomato fruits both infested and un-infested by cotton bollworm was studied using a double sided Y-shaped olfactometer in laboratory conditions. Results showed that parasitoid wasps were significantly more attracted to compounds emitted by larvae and larval faeces of the cotton bollworm. Response of parasitoid wasps to volatiles of larvae in comparison with infested tomato and corn ear indicated that 71.74% and 68.09% of wasps were attracted to odors of host larvae, respectively. Wasps did not show response to the odors released from un-infested tomato fruit and corn ear. There was no significant difference in attraction of parasitoid wasps to faeces of larvae that fed on tomato and corn ear. Our results indicated that volatile compounds produced by fifth instar larvae and larval faeces of H. armigera are important agents for attracting parasitoid wasps.

Keywords

• cotton bollworm
• olfactometer
• herbivorous induced plant volatiles
• kairomone