Scent plays a crucial role in the life of ants. Each member of a colony identifies itself through distinctive hydrocarbon scents. However, a recent study from researchers at the Max-Planck Institute indicates that human air pollution is disrupting these vital scents, causing chaos within ant societies.
The specific scent of an ant species consists of stable alkanes mixed with unique alkenes exclusive to each colony. Unfortunately, these alkenes are highly reactive with ozone, which, due to human activities, has seen a rise in concentration.
In areas away from cities, ozone levels usually peak around 10 parts per billion, whereas urban environments can see this number rise dramatically, sometimes reaching between 30 and 200 parts per billion based on pollution levels.
The study aimed to investigate whether heightened ozone exposure would alter the ants’ scent profile, potentially leading to aggression within their colonies. The lead researcher, Nan-Ji Jiang, expressed this concern.
The findings confirmed that exposure did indeed change their behavior. The team tested six ant species, exposing them to air with ozone levels of 100 parts per billion, comparable to urban pollution during summer months.
Remarkably, even just 20 minutes of urban-level ozone exposure drastically affected the ants, damaging the alkenes they rely on for distinguishing friends from enemies.
All six species showed degradation in their cuticular hydrocarbons, and for five of those species, the impact was severe enough that members began to attack and threaten their own colony mates who had been exposed to ozone.
One researcher, Markus Knaden, mentioned that while they anticipated ozone would affect nest mate recognition, the extent of the behavioral change was surprising. It turns out that these small quantities of alkenes are vital for maintaining the colony’s odor identity.
Additionally, a separate experiment revealed that small ant colonies, along with their larvae, also suffered from exposure to urban ozone levels. This exposure led to disrupted brood care, leading to the death of larvae.
With roughly 30,000 ant species globally, and their biomass equating to that of all birds and mammals combined, ants play significant roles in the environment—like aerating soil, dispersing seeds, and cleaning ecosystems. Their complex social structures offer insights that humans might learn from.
While issues like pesticide use, climate change, and habitat destruction are commonly linked to global declines in insects, this study highlights the potential for air pollution to interfere with insect societies in unknown ways.
Previous research has shown that oxidizing pollutants like ozone can disrupt interactions between flowers and their pollinators, as well as the communication methods of various fly species. The findings suggest that the adverse impacts of such pollutants may extend even further, threatening the integrity of eusocial colonies.
This research appears in the Proceedings of the National Academy of Sciences.
