The research at the University of Lausanne, Switzerland, suggests Florida carpenter ants can collectively determine their communities by shifting the cocktail of proteins, hormones as well as other molecules that are little they pass mouth-to-mouth to one another and their young through a process called trophallaxis.
"Food is passed to each adult and developing ant by trophallaxis. This creates a network of interactions linking every person in the colony," says senior author Laurent Keller, Professor in the Department of Ecology and Evolution.
"But trophallaxis occurs in other circumstances, like when an ant is reunited with a nest-partner after isolation. We thus wanted to see when the fluid exchanged by trophallaxis includes molecules that allow ants to pass other chemical messages to every other, and never just food."
Astonishingly, they identified a great number of proteins that appear to be involved in regulating the growth of ants, as well as elevated rates of juvenile hormone, a crucial regulator of insect development, reproduction, and behaviour.
To see what effect this hormone has on the development of larvae fed by trophallaxis, the scientists added it to the food of larvae-rearing ants and discovered that the hormone made it twice as likely the larvae would live to reach maturity.
"This signals that juvenile hormone and other molecules transferred mouth-to-mouth over this social network could be used by the ants to jointly determine how their colony develops," says LeBoeuf. "So, when the ants feed their larvae, they're not just feeding them food, they are casting quantitative ballots for their colony, doling out different amounts of growth-promoting components to influence the next generation.
As well as development proteins and juvenile hormone, the team also identified small molecules and chemical signals in the carpenter ants' trophallactic liquid that help them comprehend their nest-mates. They attested for the first time the presence of chemical signals in the fluid that are regarded as significant in supplying a colony to ants -special odour which allows them to recognise family -family members.
"Overall, we show that liquid carried among ants includes considerably more than food and digestive enzymes," adds LeBoeuf. "Our findings imply that trophallaxis underlies a private communication channel that ants use to direct the development of the young, much like milk in mammals."
"More generally, this opens the possibility the oral exchange of fluids, for example, spit, in other animals might also function formerly unsuspected purposes."