Dryas iulia (Lepidoptera, Nymphalidae) larval choice and performance on four Passiflora species

Abstract

The interaction among the Heliconiini butterflies and their Passiflora species is of great importance in ecology and coevolution studies. For the Heliconiini, the ability to choose a suitable host plant is determinant for the larval performance and conservation initiatives that target these species. Herbivorous insects may choose their food based on factors such as nitrogen and water content, as well as leaf digestibility and defences. In this study, we experimentally evaluated Dryas iulia (Nymphalidae) larval choice regarding four Passiflora (Passifloraceae) and the larval performance on the two most consumed species. We tested the hypothesis that D. iulia larvae would choose the Passiflora species with higher nutritional quality and lower physical defence. Dryas iulia larvae preferred P. misera (60.5% leaf consumption) over P. pohlii (28.9%), P. suberosa (15.5%), and P. edulis (not consumed). Passiflora misera presented the highest content of nitrogen and the third content of water, was ranked the second in non-glandular trichome density and did not present glandular trichomes. On P. misera, D. iulia presented the highest survival (23.1%), conversion efficiency (32.8%), relative growth rate (14.8%), heavier pupae (15.2%), and the lowest relative consumption rate (13.8%). Thus, in this experimental study, D. iulia larvae were able to choose the plant material that supported greater performance. Passiflora misera was the most suitable host species for conservation and management purposes of this Heliconiini butterfly.