Brood care strategies by newly mated monogyne Solenopsis invicta (Hymenoptera: Formicidae) queens during colony founding

Abstract

For most species of ants, newly mated queens found new colonies from stored body reserves, and without the assistance of workers. Consequently, until the first batch of colony members hatches, newly mated queens face a potential shortage of labor for brood care. The purpose of this study was to describe the brood rearing strategies of newly mated monogyne Solenopsis invicta queens, under controlled laboratory conditions, to determine how they compensated for the lack of worker labor in rearing the first batch of colony members. Newly mated S. invicta queens were collected (n = 60) and reared individually in artificial nests in the laboratory under optimal incubation conditions. Using video-technology, brood care activity by newly mated queens was quantified and compared with brood care activity of mature queens who were incubated with workers. In addition, newly mated queens and their offspring (i.e., the incipient colony) were censused biweekly for 6 mo to determine the ontogeny of the adult:larva ratio. Results from this study revealed that newly mated queens spent 65% of their time engaged in brood care activities; queens incubated with workers spent <1% of their time tending brood. Newly mated queens laid two kinds of eggs, viable and trophic. Trophic eggs were ingested by the queen, and then regurgitated to larvae. In the second phase of colony founding, after the first worker offspring hatched, the adult:larva ratio was >1:1. Consequently, larvae were never in competition with each other for worker attention. In summary, this study revealed that newly mated queens were endowed weith a suite of compensatory brood rearing strategies enabling them to succeed in founding a colony in the absence of worker labor.