Climate Change

Ants can’t alter behaviour to deal with warmer climate: Report

Heat stress on the insects will mean higher metabolism and food demands along with a shorter lifespan

By Rohini Krishnamurthy
Published: Tuesday 17 January 2023
The body temperatures of ants depend on external sources like sunlight. Photo: iStock_

Ants may be unable to adapt to global warming, a new study looking at their behavioural flexibility has warned. This leaves them highly vulnerable to impacts of climate change, as the insects could not move away from warmer sites despite costs to their well-being, suggested the paper published in the Journal of Animal Ecology

The insects are cold-blooded creatures, also called ectotherms. Their body temperatures depend on external sources like sunlight. Humans (endotherms), on the other hand, maintain their body temperature without relying on the environment.

Read more: Why insects are crucial for ecological balance

As ants’ body temperature varies with the environment, they are thought to be highly vulnerable to climate change, suggested the paper.  

“If ants warm up due to climate change, they will have a higher metabolism and food demands; we generally expect them to have a shorter lifespan as well,” Elsa Youngsteadt, professor of applied ecology at North Carolina State University and co-author of the study, told Down To Earth.

Ants are often called “ecosystem’s engineers”. These insects move the soil during nest-building and foraging, affecting the level of nutrients in it, according to a previous study.

Youngsteadt and her team wondered if ants respond to global warming by evolving to function in warmer temperatures or adjusting their behaviour by avoiding hotter environments.  

“The answers to these questions could make the difference between extinction versus persistence of many insect species,” she explained.

The researchers chose five ant species. They measured air temperatures at collection sites in the forests and used a special thermometer to record the insects’ temperatures. Some ants were taken to the lab and placed in a rectangular chamber with a gradient of temperatures.

Read more: 29 new insect species identified in south, North East India

The ants choose a particular temperature, allowing researchers to estimate their comfortable or preferred temperature. 

However, ants in the wild did not stay in preferred cooler environments. Instead, most species were found in warmer sites. This suggests that insects are either unaware or unable to adjust their behaviour by avoiding warmer ecosystems. 

“It’s interesting that the worker ants we observed were willing to put themselves in uncomfortable situations while foraging (searching for food),” Sara Prado, adjunct professor and co-author of the study, said in a statement.

previous study on 38 insect species found that 19 would suffer population decline in response to warming. Of them, 17 could escape this fate by altering their behaviour. 

Other studies have shown that ants avoid lethal temperatures. But this new study suggests that these insects may lack the behavioural flexibility to stay in their preferred temperatures. 

Alternatively, they may be “choosing” uncomfortable conditions because the benefits of finding food outweigh the costs. They could also be sacrificing their well-being for the sake of the colony, according to Prado.

Read more: Stinging: Insect taxonomy expertise in Europe may be at risk

The researchers only studied mild habitats that experienced moderate warming. In the future, they want to explore more extreme environments to understand if ants undergo behavioural change.

They also want to study the link between the ants’ foraging activity and the nest. Nests, the expert explained, are typically more insulated and are hence more protected against climate change.

We want to study if the colony’s overall success changes when the nest is buffered, but the workers who supply food to that nest are not, Youngsteadt said. 

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