Ants secrete a milky fluid to feed their young in their own version of breastfeeding, new research has revealed.
The discovery has been compared to the parental care mammals provide to their offspring after the fluid was discovered to play a critical role in colony survival.
The study also has important implications for our understanding of how insect communities have evolved and organized.
Researchers found that adult ants harvest the milky fluid from pupae just before they hatch, when they secrete large amounts of the nutrient-rich substance, similar to mammalian milk.
Ant eggs hatch to form larvae, which pupate before emerging as adults, but entomologists previously assumed the pupae did not interact with the colony.
In fact, the liquid is either consumed directly by adult ants or by the developing larvae, which receive the nutrient-rich substance from the adults.
Larvae that do not have access to the secretion show stunted growth and poor survival, while pupae that remain stagnant in their own secretion develop fungal infections and die.
Lead author Professor Daniel Kronauer, from The Rockefeller University in New York, said: “The first few days after hatching, larvae depend on the fluid, almost as a newborn depends on milk.
“The adults also drink it avidly and although it is not clear what it does to the adults, we are convinced that it affects metabolism and physiology.
“It probably evolved once, early in the ant’s evolution, or even prior to the ant’s evolution.”
The fluid contains hormones and psychoactive substances and is believed to influence the behavior and physiology of colony members.
Fluid consumption affects the health of the entire colony
The health of the entire colony seems to depend on the rapid consumption of this nutritious liquid.
In lab experiments, first author Dr. Orli snir ants at different stages of development from the colony to study how social isolation affected the insects.
She noticed the fluid build up around the isolated pupae and it wasn’t until she removed it manually that they survived to adulthood.
Dye-detection tests showed adults and larvae drank the milky substance, and analysis showed it is derived from a conserved process called molting, in which all insects shed their old cuticles to grow.
While non-social insects recycle the molting fluid to preserve nutrients, ant pupae share it with their nest mates.
The liquid is rich in nutrients, psychoactive substances, hormones and some of the components found in the royal jelly that honey bees reserve for queen bee larvae.
While ants of all ages seem to enjoy the fluid, young ant larvae need it, as those deprived of fluid for the first four days of life fail to grow and many eventually die.
Prof Kronauer said: “The way ants use this fluid creates a dependency between different stages of development.
“It just shows to what extent ant colonies really operate as an integrated unit.”
The ant colony is sometimes referred to as a superorganism – a unified entity made up of many organisms working together.
Dr. Snir said, “Pupal social fluid drives a central and hitherto overlooked interaction network in ant communities.
“This reveals a new aspect of dependency between larvae and pupae, and pupae and adults.”
She added: “This study only provides a glimpse into the intricate interaction networks of insect communities.
“Our long-term goal is to gain a deep understanding of the neural and molecular mechanisms that govern social organization, and how these mechanisms have evolved.”