The effect of colony size and starvation on food flow in the fire ant, Solenopsis invicta (Hymenoptera: Formicidae)

Abstract

Food-sharing experiments were performed with laboratory colonies of Solenopsis invicta containing 1000, 10,000, or 20,000 workers and starved for 0, 3, 7, or 14 days. The effect of these variables was measured on the uptake of radioactive sugar water (1 M) by 1% of the colony's workers and on the trophallactic flow of food from these foragers to the remainder of the colony. Patterns of food distribution in small colonies differed significantly from those in larger nests. In 1000-ant nests, small workers more frequently received food than large workers, but in bigger colonies the opposite occurred. Fire ants were adept at distributing sugar water, with food from a few workers rapidly reaching the majority of the colony as foragers donate their crop contents to groups of recipients and these recipients may themselves act as donors. Foragers respond to colony starvation by individually taking up more food and sharing this fluid with a greater proportion of nestmates. Even foragers from satiated colonies can retrieve at least small amounts of liquid. The forager's state of hunger plays an important role in regulating food distribution. In sugar-satiated nests, previously starved foragers are highly successful at passing on labelled sugar whereas prviously fed foragers are not. © 1980 Springer-Verlag.