Social exchange of chemical cues, growth proteins and hormones through trophallaxis

Social insects frequently engage in oral fluid exchange – trophallaxis – between adults, and between adults and larvae. Although trophallaxis is normally considered a simple food-sharing mechanism, we hypothesized that endogenous components of this fluid might underlie a novel means of chemical communication that directly influences colony organization. Through protein and small-molecule mass spectrometry and RNA sequencing in the ant Camponotus floridanus, we found that trophallactic fluid contains a set of specific proteins, hydrocarbons, microRNAs, and Juvenile Hormone, an important insect growth regulator. Comparison of trophallactic fluid proteins across social insect species (ants Camponotus fellah and Solenopsis invictis, honeybees Apis mellifera) revealed that many are regulators of growth and development. These results raise the possibility that, in addition to its role in food transfer, trophallaxis is a mode of communication that enables communal control of colony phenotypes.