Battus polydamas(Lepidoptera: Papilionidae) Uses the Open-FieldAristolochia sessilifolia(Piperales: Aristolochiaceae) as Its Host Plant in Uruguayan Savanna Areas

Abstract

Butterfly species with broad geographical ranges are expected to be tolerant of ecological/ environmental constraints and to shifts in host plant use. This seems to be the case of the butterfly Battus polydamas (Linnaeus, 1758) (Lepidoptera: Papilionidae), which in the absence of better host plants may lay eggs on low-quality Aristolochia (Piperales: Aristolochiaceae) plants, increasing the developmental time and mortality rate of immatures. Battus polydamas populations from the Uruguayan savanna were investigated to verify whether A. sessilifolia (Klotzsch) Duch. was being used as a host plant in grassland areas where no other Aristolochia species are available. Species distribution models (SDM) for both species were built to verify whether ecological conditions could cause overlapping distributions between them. Extensive field surveys were performed to investigate whether B. polydamas actually uses A. sessilifolia as larval food source in the field. The performance of larvae on such host plant was also tested under controlled conditions in a laboratory environment. The SDM analysis showed a large overlap between the distributions of B. polydamas and A. sessilifolia. Field surveys revealed the occurrence of an interaction between the butterfly and the potential host plant, and laboratory experiments corroborated that B. polydamas larvae can successfully use A. sessilifolia as a host plant. The wide distribution of B. polydamas suggests that this butterfly species evolved the ability to develop in unfavorable environments (e.g., poor host plants, adverse climate), allowing it to use virtually all Aristolochia species of the Neotropics as host plants. Thus, adult females appear to have developed the capacity to identify any Aristolochia spp. as a suitable host plant, enabling the exploitation of various landscapes and ecoregions.