Ant-Related Oviposition and Larval Performance in a Myrmecophilous Lycaenid

We experimentally assessed ant-related oviposition and larval performance in the Miami blue butterfly (Cyclargus thomasi bethunebakeri). Ant tending had sex-dependent effects on most measures of larval growth: female larvae generally benefitted from increased tending frequency whereas male larvae were usually unaffected. The larger size of female larvae tended by ants resulted in a substantial predicted increase in lifetime egg production. Oviposition by adult females that were tended by C. floridanus ants as larvae was similar between host plants with or without ants. However, they laid relatively more eggs on plants with ants than did females raised without ants, which laid less than a third of their eggs on plants with ants present. In summary, we found conditional benefits for larvae tended by ants that were not accompanied by oviposition preference for plants with ants present, which is a reasonable result for a system in which ant presence at the time of oviposition is not a reliable indicator of future ant presence. More broadly, our results emphasize the importance of considering the consequences of variation in interspecific interactions, life history traits, and multiple measures of performance when evaluating the costs and benefits of mutualistic relationships. 1. Introduction For egg-laying animals that do not provide parental care, oviposition location is among the most important maternal decisions affecting subsequent offspring performance [1, 2]. Consequently, when growth and survival of immature stages are strongly influenced by other species—either positively or negatively—spatial patterns of oviposition often reflect these interactions [3–7]. In mutualistic relationships, we might expect preferential oviposition and improved performance when and where mutualists are present, but tradeoffs and constraints in both oviposition choices and immature growth strategies may make such simple correlations rare. Most lycaenid butterfly species interact with ants, and many of these relationships include substantial benefits for lycaenid larvae [8]. However, the costs and benefits of ant tending for larval growth of lycaenids vary substantially among systems. For example, larvae of Jalmenus evagoras and Glaucopsyche lygdamus pupate at a greater mass when untended by ants [9–11] but are dependent on ants for protection under natural conditions. By contrast, larvae of Paralucia aurifera and Hemiargus isola pupate at a greater mass and developed faster when reared with ants [12, 13]. Other studies have found that the consequences of ant tending on