Myrmecophilous Parrhasius polibetes butterflies (Lycaenidae) improve offspring survival near ant-tended treehoppers

Mutualisms have been intensively studied but demonstration of indirect effects between co-occurring mutualistic systems is rare. Here, we examine the selective pressures mediating co-occurrence of a facultative ant-tended butterfly (Parrhasius polibetes) with ant-tended Guayaquila xiphias treehoppers on Schefflera vinosa (Araliaceae). Host plant selection and caterpillar survival in P. polibetes were investigated in the presence and absence of ant-Guayaquila associations. Paired trials showed that butterflies preferably lay eggs on branches occupied by ant-tended treehoppers than on branches without this interaction. Occurrence of an ant-treehopper association on foliage reduced the abundance of P. polibetes’ natural enemies and increased larval survival both in pre-myrmecophylic and ant-tended phases. Thus butterflies opportunistically exploit the enemy-free space generated by tending ants around the treehoppers. Detection of other ant-based mutualisms upon egg-laying to improve caterpillar survival may have represented an important evolutionary step in the process of host plant selection in facultative myrmecophilous butterflies (supported by FAPESP, CNPq, NSF).