Ant tending of Miami blue butterfly larvae (Lepidoptera: Lycaenidae): Partner diversity and effects on larval performance

Abstract

The larvae of many lycaenid butterflies (Lepidoptera: Lycaenidae) are tended by ants that protect them from natural enemies in return for sugar-rich secretions that the larvae produce to attract and retain their ant guards. We investigated the relationship between larvae of the endangered Miami blue butterfly (Cyclargus thomasi bethunebakeri Comstock & Huntington) and potentially mutualistic ants. We observed 10 ant species interacting with Miami blue larvae in the field, and raised larvae successfully in captivity with 3 of these and 6 other ant species that are not known to tend larvae in the wild. In an experimental assessment of ant effects on larval performance, we found no differences in age at pupation, pupal mass, length of pupation, total time as an immature or ratio of time as a larva to time as a pupa among larvae raised with Camponotus floridanus Buckley, Linepithema humile Mayr, or in a no-ant control. Larvae raised with C. floridanus were significantly more likely to pupate in the ant harborage than larvae in the other treatments. We did not observe ants behaving antagonistically toward Miami blue larvae in field, laboratory, or experimental conditions; even ant species previously identified as potential predators tended larvae. Our results demonstrate that Miami blue larvae can elicit typical tending behaviors across diverse ant taxa and that ant tending does not substantially alter larval development, findings that may have implications for conservation and population restoration of the Miami blue butterfly.