AGRAULIS AND PASSIFLORA II. BEHAVIOR AND SENSORY MODALITIES

¹ Department of Biological Sciences, University of California, Santa Barbara, California 93106

1. The behaviors and sensory modalities involved in the selection of Passiflora host-plants for oviposition by the heliconian butterfly Agraulis vanillae were investigated.

2. Ovipositing females are attracted to oviposit near green leaf-shaped objects on the basis of generalized visual cues but make no ovipositional distinction between P. alato-caerulea and P. edulis, which are readily discriminated when full access to the vines is allowed.

3. The rate of oviposition by female Agraulis is accelerated by odors from P. alato-caerulea and P. caerulea, retarded by odors from P. manicata and Passiflora sp., and not affected by odors from P. edulis or P. mollissima.

4. Contact-chemical stimulants and inhibitors of oviposition are presumed to exist in the leaves of passion-vines on the basis of circumstantial evidence. Attempts to demonstrate directly their existence have not yet been successful.

5. Female Agraulis exhibit a positive anemotactic response in an airstream that has passed over one of at least two species of Passiflora, P. alato-caerulea and P. manicata, but not in an airstream passed over P. mollissima.

6. A mark-release-recapture study of adult movements among three passion-vines demonstrated that butterfly subpopulations tend to form on each vine with little exchange between different subpopulations.

7. The primary factor determining the infestation level of a particular Passiflora by Agraulis is the balance of chemical cues directly involved in oviposition that are present in that Passiflora. Possible functions for the upwind flight response are suggested. Further research on the plant chemistry of the family Passifloraceae as it relates to heliconian behavior would broaden our understanding of heliconian-Passiflora coevolution.