Relationship between juvenile hormone and defensive behavior in the little fire ant Wasmannia auropunctata

Regulation by hormones is an important physiological mechanism in organisms. Insects have hormones that control development and reproduction. Among them are the juvenile hormones (JH), which regulate many physiological processes including development, reproduction, diapause, and polyphenisms. JH has an important role in behavioral development of social insects such as the honey bee, where JH levels affect onset of defensive behavior. In contrast with honey bees where older individuals perform hive defense, in the little fire ant Wasmannia auropuctata, young individuals perform nest defense. We want to evaluate the relationship between JH and nest defense in this ant. We expect JH levels to be high in ants that perform defense. To determine this relationship we sampled a group of 25 foragers and nurses to which we administered the JH analog methoprene. We introduced an unfamiliar species of ant and observed defensive behavior. Preliminary data indicate that nurses treated with methoprene do not perform defense while forager, who typically do not defend behaved more like nurses by defending the nest. The results of this study have important implications for the understanding of the development and evolution of behaviors in this invasive ant.