Disrupted Ant Peace: How the Climate Brings New Enemies

More heat, less peace: this is what ant researchers have observed at different altitudes in Austria, Italy, France and Switzerland.

, which is widespread in the mountains

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Joachim Müller-Jung

Editor in the feuilleton, responsible for the "Nature and Science" department.

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Among the ants, crawling insects are among the more peaceful insects.

They are also comparatively sedentary, like many species in the steep mountain world, where the external conditions change very quickly with altitude and the ecological needs of the animals can then quickly no longer be met.

In the cold habitat of many high-Alpine Tetramorium alpestre populations, frequent conflicts would therefore primarily mean energy losses, and they probably avoid them for this reason.

The ants prefer to content themselves with foraging for food.

For example, they milk aphids that reproduce on the plants.

Conflicts mean energy losses

In a warmer habitat, virtually everything changes: the soldiers and workers grow larger, their jaw weapons more powerful, and their crippling ant venoms stronger.

Apparently, heat directly increases their readiness to be aggressive, which is also shown by the researchers' behavioral experiments with the soldier ants.

Their passion for hunting and aggressiveness, also towards neighboring ant colonies, is clearly awakened.

In a warmer habitat, however, not only the temperatures change, but also the availability of nutrients such as nitrogen.

In addition, parts of the wilderness are too literally over-fertilized by air pollutants.

The ants, one could say, live more luxuriously when it comes to their food sources.

But that also increases the aggressiveness.

In general, the warmer the environment, the greater the range of plants and prey, which in turn increases the competitive pressure and at the same time the ability to defend yourself - for example, the ants then also have the opportunity to produce different paralyzing toxins.

Eight populations of high alpine ants were compared for the study by the Austrian-German research group led by Patrick Krapf from the University of Innsbruck.

47 individual colonies were examined and the behavior of the animals, the composition of the colonies and their secretions were randomly analyzed using molecular biology.

As Krapf and his Ulm-Innsbruck team report in the journal "Science of The Total Environment", the soldiers in the warmer regions of France and Italy are "many times" more aggressive than in the cooler locations of Austria and Switzerland - regardless of genetic and social influences such as relationship, colony size or the number of queens.

The short-term survey makes it difficult to say whether these changes in behavior towards more hostility will become even more prevalent in the event of stronger warming, which is hardly anywhere faster than in the Alpine regions.

The authors expressly warn against generalizations in their publication.

In fact, a current American ant study contains examples of ants from urban regions that make it clear that many ants, with their enormous ecological adaptability, react rather sluggishly to accelerating climate change trends.

However, the connection between heat and aggression has already been demonstrated in other animal species, such as voles or mountain goats.