Chemosensory basis of host recognition in butterflies--multi-component system of oviposition stimulants and deterrents.

Larvae of most butterfly species feed on a limited number of host species belonging to a single plant family. The choice of host plants is determined both at the egg-laying and larval-feeding stages (Schoonhoven et al., 1998). The choice of oviposition site by an adult female is crucial to the survival of their offspring, and thus the mother butterflies lay their eggs with great precision on the host plants. Although host recognition by phytophagous insects involves multiple sensory modalities, including visual, olfactory and gustatory cues, contact chemical stimuli from host and non-host plants play an important role at the final step of egg-laying behavior. The contact chemoreceptors responsible for detection of both host and non-host allelochemicals at oviposition are located on the foretarsi of the female butterfly (Roessingh et al., 1991; Nishida, 1995). Oviposition stimulants