Climate Change: Underground Army Ants Can't Cope with High Temperatures

Some species just can't take the heat, and underground ants are one of them. Scientists have found that certain army ant species that live in tropical forests are ill-suited to high temperatures.

There are several different species of army ants, the aggressive insects that swarm predators underfoot in the jungle. Yet underground species of army ants are much less tolerant of high temperatures than their aboveground relatives. This difference in thermal tolerance, in fact, could mean that climate change may greatly impact army ants.

"A few inches of soil can make a big difference in temperature," said Kaitlin Baudier, lead author of the new study, in a news release.

In order to see whether living above ground and below ground affected a species' thermal range, the researchers examined nine closely related species of army ants that lived in the same general area in Costa Rica's tropical forests. The scientists sampled ants from each of the species and experimentally tested their maximum heat tolerance in the lab.

The researchers found that the best predictor of heat tolerance was how active the ant species was in above-ground environments. In fact, above-ground army ants were most tolerant of higher temperatures while species that used a combination of above- and below-ground environments had intermediate levels of tolerance. Not surprisingly, those who were most active above-ground were also the most heat tolerant.

"This shows us that the ways these species respond to a changing climate will be different depending on habitat type, and it's important to know that microhabitat could be an indicator of heat tolerance," said Sean O'Donnel, one of the researchers.

The findings are published in the Journal of Animal Ecology.

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