Behavioral response of femaleHelicoverpa (Heliothis)armigera HB. (Lepidoptera: Noctuidae) moths to synthetic pigeonpea (Cajanus cajan L.) kairomone.

FemaleH. armigera moths are highly attracted by a steam distillate from pigeonpea plants, one of their main hosts. A mixture of six compounds, all sesquiterpenes (β-caryophyllene,α-humulene,α-guajene,α-muurolene,γ-muurolene, andα-bulnesene), mixed in the proportions as found in the steam distillate, elicited the same behavioral responses (oriented upwind flights and contacts with the odor source) as the steam distillate. Onlyα-bulnesene was attractive by itself, but still less than the whole mixture. In addition, the sesquiterpene mixture acts as an oviposition stimulant. Both behavioral responses, orientation and oviposition, are concentration dependent. Electrophysiological recordings from female and male antennae (EAG) showed the same qualitative and quantitative responses to each of the compounds of the sesquiterpene mixture. The EAG responses to the original steam distillate were higher and similar to chickpea kairomonal components, which were also tested. The pigeonpea sesquiterpene mixture and its individual components elicited weak EAG responses only. The response of the male antenna to female-produced pheromone components was in the same range as the pigeonpea steam distillate.