Monday, December 10, 2007 - 10:05 AM

Fallen-fruit associated aggregations in ithomiine butterflies (Nymphalidae)

Ryan I. Hill,, University of California, Department of Integrative Biology, 3060 Valley Life Sciences Building, Berkeley, CA and Jarol F. Vaca, Fundacion Bromelia, Av. Amazonas 853 y Ventimilla, Quito, Ecuador.

Adult aggregations of unpalatable, warningly colored ithomiine butterflies have been documented in several contexts including near army ant swarms, in pockets of humid forest, at pyrrolizidine alkaloid sources, and on leks. In this study we describe ithomiine aggregations that are associated with several tree species dropping ripe fruit. Focal observations under fruiting Clarisia racemosa (Moraceae) trees illustrated that these aggregations involve individuals of both sexes feeding on fallen fruit, and that aggregations are slightly female biased (54.4% female). Displaying males are present, but in low frequency with little associated courting, leading us to question the use of the term lek for all ithomiine aggregations containing displaying males. Samples from under four trees hosting aggregations demonstrated that butterflies were not found more often with like mimicry patterns, rejecting the hypothesis that the aggregations were specific to one color pattern. However, species involved in these aggregations are primarily from more derived ithomiine taxa and aggregations are comprised predominantly of “non-tiger” mimicry patterns. Accordingly, we suggest these aggregations play a role in the evolution and maintenance of mimetic diversity within ithomiines.

Species 1: Lepidoptera Nymphalidae (Ithomiinae)