As a student of ant species in the Amazon rainforest of French Guiana, our research sheds light on an unexpected diversity and sophistication shaped by the prey they consume, their social behavior, and the need to protect themselves against predators. These results, published in “Molecular Ecology” and “Science,” offer new insights into the evolution of venoms in social insects.
We discovered that not all ants in a colony have the same venom composition. In legionary ants, the venom of soldiers contains digestive enzymes, likely involved in prey digestion. In the ant Neoponera goeldii, the venom contains a molecule that mimics a green leaf hormone, causing immediate pain to deter predators.
Venoms are complex mixtures of dozens or even hundreds of biologically active molecules used to immobilize prey and defend against threats. Research has primarily focused on large venomous animals like snakes, scorpions, and spiders. Today, these venoms are also being studied for their therapeutic potential, as some toxins have inspired commercial medications.
Initially isolated by John Wray in 1670, the first venomous compound identified was formic acid from Formica ants. Although nearly all ants are venomous, not all sting. Approximately half of species have a functional stinger like wasps and bees, injecting protein-rich venom.
These venoms have long been understudied because each ant produces only a few nanoliters, making collection and analysis challenging. With nearly 15,000 described species, ants are an immense reservoir of chemically diverse compounds that are largely unexplored.
Before studying venoms, researchers must locate and collect ant colonies in the forest, where ants occupy all levels of the terrestrial ecosystem. In the lab, ants are dissected individually under a binocular microscope to extract venom reservoirs. Advanced techniques like mass spectrometry and RNA sequencing are used to analyze venom composition.
Among the species studied, legionary ants (Eciton hamatum) drew attention for their unique nomadic lifestyle and specialized social organization. Soldiers have enlarged hook-shaped mandibles for effective defense, while minors handle colony tasks and defense. Both types possess a painful venom, with soldiers also containing digestive enzymes suggesting a role in prey predigestion.
One species, Neoponera goeldii, uses a venom toxin that mimics bradykinin, targeting pain receptors in predators for efficient defense. This adaptation is unique to this ant species, known for living in aerial nests called “ant gardens.” These ants build nests with plant debris and fibers, incorporating epiphytic plant seeds that germinate within the structure.
The composition of ant venoms is closely tied to the species’ lifestyle, reflecting chemical cocktails shaped by evolution to respond to specific ecological constraints.
