The exchange of fluid via mouth-to-mouth trophallaxis may play a role in colony-wide communication in social insects such as Camponotus floridanus. (Photo credit: Adria LeBoeuf)

Children are often admonished to not talk with food in their mouths. Ants, on the other hand, may be doing it regularly.

Mouth-to-mouth food sharing, known as trophallaxis, is common among social insects like ants. A new study from the University of Lausanne, Switzerland, suggests ants also “talk” and influence colony development via trophallaxis by exchanging a mix of proteins, hormones, and other chemicals linked to growth regulation and nestmate identification.

“A lot of researchers consider trophallaxis only as a means of food-sharing,” said Professor Richard Benton of the Center for Integrative Genomics, a senior author of the study, in a press release. “But trophallaxis occurs in other contexts, such as when an ant is reunited with a nestmate after isolation. We therefore wanted to see if the fluid exchanged by trophallaxis contains molecules that allow ants to pass other chemical messages to each other, and not just food.”

Benton and colleagues, led by postdoctoral researcher Adria LeBoeuf, studied fluids exchanged by Camponotus floridanus. In addition to proteins involved in regulating ants’ growth, they identified high levels of juvenile hormone, which is known to play an important role in insect development, reproduction, and behavior. They added juvenile hormone to the food of ants that feed larvae via trophallaxis and found it made the larvae twice as likely to reach adulthood.

“This indicates that juvenile hormone and other molecules transferred mouth-to-mouth over this social network could be used by the ants to collectively decide how their colony develops,” says LeBoeuf. “So, when the ants feed their larvae, they aren’t just feeding them food, they are casting quantitative ballots for their colony, administering different amounts of growth-promoting components to influence the next generation.”

The study also dug deeper into the established role of trophallaxis in nestmate identification, demonstrating the presence of specific chemicals in exchanged fluid that aid ants in distinguishing colony members from nonmembers.

Read more: Oral transfer of chemical cues, growth proteins and hormones in social insects (eLife)