Feeding behavior of Heliconius erato phyllis (Fabricius) (Lepidoptera: Nymphalidae) larvae on passion vines

Of the 15 species of passion vines recorded for the Rio Grande do Sul State, Brazil, nine are used by Heliconius erato phyllis (Fabricius, 1775). The larvae of this species feed preferentially on Passiflora misera H.B.K., which confers greater performance despite presenting smaller amounts of nutrients than other host plants. Thus, the performance associated with the consumption of a passion vine is possibly related not only to its nutritional content but also to the morphological and behavioral mechanisms involved in the feeding. In this study, the difficulties in accessing food imposed by the hosts (P. misera, Passiflora suberosa L., Passiflora caerulea L., Passiflora edulis Sims, and Passiflora alata Dryand.) were evaluated. Focal observations were performed every 2 min during 6-h sessions (sequential sampling), and the relative time spent for different behaviors (resting, feeding, walking, tasting, and vein cutting) was quantified on both young and old leaves. Larvae devoted more time feeding on P. misera in most cases. Larvae observed on P. alata devoted more to time resting and less time feeding, performing one or two meals of small duration, every 6 h. First instar caterpillars on old leaves of P. suberosa and P. caerulea spent more time walking, searching for a favorable feeding site. The hardness of leaves may be a limiting factor for the initial instars in this heliconian.