From acidic arrows to social shields: exploring the complex venoms of Formicine ants

Review by Erik T. Frank

Edited by Rohini Singh and Salvatore Brunetti

In a recent comprehensive review, “Acid Reign: Formicine Ants and their Venoms,” Lukas Koch, Timo Niedermeyer and Simon Tragust assemble an extensive body of research to spotlight a surprisingly intricate and versatile weapon: the formicine ant’s venom. Long recognized for their potent sprays of formic acid, formicine ants stand apart from other ant subfamilies with their ability to forego stinging, instead relying on a specialized acidopore for chemical defense.

This review delves deeply into the chemistry, morphology, and ecological importance of formicine venoms. Although these venoms have captured scientific curiosity for centuries, dating back to the earliest isolation of formic acid in the 17^th century, many questions remain. How do these ants biosynthesize and store corrosive formic acid safely within their own bodies? And how do these volatile secretions, often considered simple defensive toxins, come to serve an array of sophisticated roles, including sanitation, communication, and even countering the toxins of rival species (Fig. 1)

The review emphasizes that formicine venoms are not merely toxic fluids but complex, multifunctional biofluids. Formic acid undoubtedly plays the starring role: it can be produced in astonishing concentrations (up to half or more of the venom’s total volume) and wielded in multiple contexts. Some formicine ants use their venom to overwhelm and kill prey at a distance, projecting acid sprays over several centimeters. Others use it more strategically, first gripping an opponent with their mandibles and then applying a potent dose of acid directly into the wound (Fig. 2).

Yet the review makes it clear that formic acid is not the entire story. A suite of lesser-known compounds also lurks within these venoms, various fatty acids, aromatic compounds, and potentially peptide-like substances, though their exact identity and functions remain poorly understood. Intriguingly, the authors highlight the scarcity of data on proteinaceous toxins or peptides in formicine venoms, a major gap considering that peptides are common in other ant subfamilies and numerous venomous animals.

Beyond their direct role in predation and defense, these venoms shape the social and ecological fabric of ant life. The review synthesizes evidence that formicine ants harness their acidic secretions for tasks well outside the typical venom repertoire. For instance, workers frequently employ venom as a disinfectant. By depositing or ingesting their own venom, they can sanitize their brood, nest materials, and even their food sources, reducing the growth and spread of pathogenic microbes. These ingenious adapatations in social immunity show how chemical weapons have been co-opted and refined for communal benefit. Since in my own research I study how ants care for the wounds of their nestmates, I wonder if venoms could also be applied on the wounds of nestmates to combat wound infections?

Formicine venoms also facilitate complex communication networks. Contrary to the assumption that chemical weapons serve a single lethal purpose, formic acid and other venom constituents can function as alarm signals, triggering coordinated defensive responses or attracting nestmates to new resources. A single droplet of venom, deployed in the right social context, may mobilize an entire colony. This capacity for nuanced information transfer, combined with other glandular secretions and behavioral displays, reveals venoms as part of a multifaceted communication toolkit.

Another fascinating dimension described in the review is the ability of formicine ants to use their venom as a kind of antivenom. Some species apply their own formic acid onto themselves when battling other ants that use alkaloid-rich venoms. This chemical neutralization offers protection and highlights how dynamic and context-dependent venom functions can be.

Despite these advances, the review calls for further work. Key challenges remain in parsing the complexity of formicine venoms. Especially technological hurdles (and costs) have historically limited the identification and characterization of venom components to relatively simple analytical techniques. The authors propose that modern -omics approaches (proteomics, metabolomics, and transcriptomics) could revolutionize venom research. These cutting-edge methods, combined with spatial imaging techniques, could map venom production sites and track how venom composition varies between individuals, colonies, or seasons.

Such a comprehensive analysis could also help clarify how venom variation correlates with ecological roles, behavioral specialization, and evolutionary history. Comparing multiple formicine species systematically may reveal patterns in venom chemistry that explain why certain lineages rely heavily on formic acid, while others integrate additional toxin types or diverge in their methods of venom application.

This new synthesis underscores that formicine ants challenge conventional views of venom as a mere instrument of violence. Their venoms are better seen as adaptive, multifunctional secretions shaped by the pressures of group living, competition, and disease management. By integrating historically scattered information and highlighting emergent research directions, the authors set the stage for a deeper understanding of how these chemical arsenals evolve and operate.

In many ways, unraveling the complexity of formicine venoms parallels the broader quest to understand social insect success. Just as ants have developed intricate division of labor, sophisticated communication channels, and cooperative disease defenses, their venoms too have undergone extraordinary evolutionary innovation. Rather than serving as a mere weapon, these secretions embody a chemical cornerstone of social life, integral to the survival and prosperity of formicine ant colonies. This perspective naturally makes me wonder: to what extent might venoms in other ant subfamilies exhibit similar complexity and multifunctionality?