June 10, 2023

Unable to adapt to rising temperatures, many ants are facing a plight in climate change

Ants are one of the dominant insects in the world. They are hugely abundant, with 20,000 trillion of them buzzing on Earth, and can be found on every continent except Antarctica. They play a key role in many ecological networks and processes, but we don’t know much about their ability to respond to changes in the world’s climate. In fact, one recent study shows they may be more vulnerable to climate change than we previously thought.

Unable To Adapt To Rising Temperatures, Many Ants Are Facing A Plight In Climate Change
The Asian Needle Ant (Brachyponera chinensis), one of the ants included in the study. Image credit: Harum.Koh / Flickr.

While previous studies have found ants’ social structures could help them to adapt or tolerate climate change, a new study is now suggesting this isn’t necessarily happening — it’s a case of theory not matching up to practice. Essentially, researchers at North Carolina State University found a group of ants didn’t adjust their behavior in response to warming temperatures, living in a sub-optimal microhabitat.

“Warmer times and places make warmer ants, and they’re not adjusting their activity to match their preferred conditions,” Elsa Youngsteadt, co-author of the study, said in a statement. “For now, this may be a tradeoff that works out fine for them. But if you think of the huge biomass of ants underfoot, their metabolic rates are all creeping upward as the climate changes.”

Animals can react to climate change in three ways: They can move, adapt, or die; obviously, the former two are preferable. Some ants species are currently moving to higher elevations and latitudes to escape higher temperatures, but climate change could be happening too fast for most species. In any case, moving isn’t always a simple solution, as it can mean competing for food or interacting with unfamiliar species.

Ants and climate change

Ants are ectotherms, which means their body temperature depends on external heat sources. That is, their body temperature rises and falls along with the temperature of the environment. While these animals go through a range of temperatures in daily life, most prefer places that are slightly cooler. If they encounter a warmer environment, ectotherms can die.

The researchers studied five species of ants common in North Carolina. They counted and collected them in forest ecosystems and measured air temperatures at the sites to identify the distribution of available microhabitats. They used an ant thermometer to measure the temperatures of the ants and collected some for the lab, placing them in a chamber with controlled temperature.

They found that ants in the lab had a distinct thermal preference, but ants in the field were active in their preferred climate only slightly more often than expected. Instead, most species were collected in sites that were warmer than preferred. This suggests a lack of awareness or some limitation in the ants’ ability to adjust to higher temperatures, they said.

“It’s interesting that the worker ants we observed were willing to put themselves in uncomfortable situations while foraging,” Sara Prado, co-author of the study, said in a statement. “I wonder if the food was ‘profitable’ enough for the ants to stretch their comfort levels, or if they are simply willing to sacrifice their well-being for the sake of the colony.”

The researchers plan to continue investigating this question but with urban ants, which are living exposed to warmer temperatures in cities. In the meantime, this study brings some light into how a very important insect is coping with climate change. Unless we bring down emissions now and fast, more animals will be forced to adapt to the climate crisis.

The study was published in the Journal of Animal Ecology.