Trophallaxis by temporal subcastes in the fire ant, Solenopsis invicta, in response to honey

ABSTRACT. Trophallactic behaviour of temporal subcastes in Solenopsis invicta Buren colonies was studied in two separate experiments. First, radiolabeled honey was presented to small colonies containing larvae, queens and marked workers; radioactivity in the head, thorax and abdomen of each ant was measured after 0.25, 1, 6, 12, 24, 48 and 72 h. The quantity of honey per subcaste was dependent on the total amount of honey collected. As more honey entered the colony, the quantity in foragers, queens and reserves increased more rapidly than that in nurses or larvae. The internal distribution of radioactivity in the head, thorax or abdomen indicated that differences between subcaste members in either the rate of food exchange or digestion existed. In a second experiment behavioural observations were made on marked workers in colonies before and after the presentation of honey. Reserves spent significantly more time engaged in trophallaxis than either foragers or nurses, both as active donors and active receivers. Based on number of encounters, nurses were more likely to receive honey while reserves and foragers were more likely to donate honey. The duration of encounters involving nurses tended to be shorter than those involving reserves or foragers.