How Pollution Alters Ant Scent, Leading to Attacks on Nestmates

Common air pollutants like ozone and nitric oxide can alter the scent of ants, triggering aggressive behavior from nestmates who perceive them as intruders.

Ants rely on scent for social recognition, and when they encounter individuals with unfamiliar scents, they often react with aggression—biting or even killing the perceived invader. Notably, ozone—a greenhouse gas emitted from vehicle exhaust and industrial processes—can impact the chemical makeup of alkenes, compounds important to the unique scent profile of their colony.

Markus Knaden and researchers at the Max Planck Institute for Chemical Ecology in Jena, Germany, previously noted that ozone-induced changes in alkenes can disrupt insect communication, leading to phenomena such as fruit flies mating with inappropriate partners or pollinators like the tobacco moth losing interest in flowers. But how does ozone affect ant behavior?

To explore this, Knaden’s team established artificial colonies of six ant species, exposing them to glass chambers with varied ozone concentrations, mirroring summer levels recorded in Jena. Upon their return, the subjected ants faced attacks from their colony members.

“I honestly didn’t expect this outcome,” Knaden remarked. “We anticipated the ozone might alter just a small fraction—2 to 5 percent—of the overall scent blend.”

In natural settings, such aggressive behavior can hinder colony efficiency, even without any fatalities among the ants, though it is complex to design experiments that effectively measure these impacts.

Daniel Cronauer, a professor at Rockefeller University in New York, commented that the aggression observed is not surprising given the crucial role alkenes play in identifying nestmates.

Alkenes also facilitate other vital ant behaviors, including tracking via footprints and communication between larvae and adults. This study indicates that ozone exposure may lead clonal ant adults (Oseraea Billoi) to neglect their larvae, suggesting that these changes could disrupt various facets of ant life and potentially affect broader ecosystem dynamics.

“In most terrestrial ecosystems, the removal of ants would likely lead to catastrophic consequences,” Cronauer stated. Ants are pivotal for dispersing seeds, aerating soil, and fostering symbiotic relationships with other species.

With global insect populations in decline, this research adds to a growing body of evidence linking air pollution to these declines. Knaden asserts that while current ozone levels may not pose immediate dangers to humans, “we must acknowledge the unseen consequences of our actions.”

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