Although mutualisms have been intensively investigated, demonstration of indirect effects between co-occurring mutualistic systems is rare. For instance, the ecological consequences of co-occurrence of ant-tended insects on a plant have never been examined for survival effects on either trophobiont species. Here, we assess the selective pressures mediating co-occurrence of a facultative ant-tended butterfly (Parrhasius polibetes) with ant-tended treehoppers (Guayaquila xiphias) on Schefflera vinosa shrubs. We evaluated host plant selection and caterpillar survival in P. polibetes in the presence and absence of ant-treehopper associations. Paired trials revealed that butterflies preferably oviposit on branches hosting ant-tended treehoppers when they had a choice between those and branches without this interaction. Presence of ant-tended treehoppers on a branch reduced the abundance of P. polibetes' natural enemies and improved caterpillar survival in both premyrmecophylic and ant-tended phases. Thus ant-tended treehoppers create an enemy-free space on foliage that butterflies exploit to protect larval offspring. These findings connect two widely documented ant-trophobiont mutualisms and highlight the importance of considering multiple interactions for a proper understanding of ant-plant-herbivore systems. Detection of other ant-based mutualisms on oviposition to improve offspring survival may have represented an important evolutionary step in the process of host plant selection in facultative myrmecophilous butterflies.

ABSTRACT. External morphology of the immature stages of neotropical heliconians: IV. Dryas iulia alcionea (Lepidoptera, Nymphalidae, Heliconiinae). The external features of egg, larva and pupa of Dryas iulia alcionea (Cramer, 1779) are described and illustrated.

The underlying mechanisms mediating the use of multiple host plants were investigated in Parrhasius polibetes (Lycaenidae), a florivorous and facultative myrmecophilous butterfly. Plant traits such as presence of ant-treehopper associations as a source of enemy-free space, flower bud dimensions, toughness, thickness, trichomes, and the corresponding performance and wear of P. polibetes mandibles were examined for three natural hosts: Schefflera vinosa (Araliaceae), Pyrostegia venusta (Bignoniaceae) and Luehea grandiflora (Malvaceae). Parasitism levels of larvae found on the three hosts were also determined. Almost all Luehea had ant-treehopper associations, and all larvae found on this host were non-parasitized. Parasitism was low in larvae found on Schefflera, half of which hosted ant-treehopper associations. No ant-treehopper association was found on Pyrostegia, where parasitism was significantly higher compared to other hosts. In the laboratory, P. polibetes performed well on Schefflera, followed by Pyrostegia. No larvae survived when fed with Luehea. Flower buds of Luehea were thicker and tougher than those of Schefflera and Pyrostegia. Indeed, mandibles of larvae reared on Luehea showed substantial wear, whereas those reared either on Schefflera or Pyrostegia presented no significant damage. Additionally, we suggest that co-occurrence with ant-treehopper associations on a plant provides parasitoid-free space for P. polibetes larvae. Our results support the hypothesis that ecological trade-offs among host plants (i.e., food quality and enemy-free space) promote polyphagy in natural populations of P. polibetes. Host morphological traits seem to play a relevant role in P. polibetes performance. To our knowledge, this is the first report showing the costs of polyphagy in a myrmecophilous butterfly.

ABSTRACT. External morphology of the immature stages of neotropical heliconians: V. Agraulis vanillae maculosa (Lepidoptera, Nymphalidae, Heliconiinae). The external features of egg, larva and pupa of Agraulis vanillae maculosa (Stichel, [1908]) are described and illustrated, based upon light and scanning electron microscopy.

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