High temperatures threaten the survival of insects

An insect is sitting on a tree trunk. Photo.
A banded demoiselle, one of the two species studied (Photo: Erik Svensson)

Insects have difficulties handling the higher temperatures brought on by climate change, and might risk overheating. The ability to reproduce is also strongly affected by rising temperatures, even in northern areas of the world, according to a new study from Lund University in Sweden.

Insects cannot regulate their own body temperature, which is instead strongly influenced by the temperature in their immediate environment. In the current study, the researchers studied two closely related species of damselflies in Sweden. The goal was to understand their robustness and ability to tolerate changes in temperature.

To study this, the researchers used a combination of fieldwork in southern Sweden and infrared camera technology (thermography), a technology that makes it possible to measure body temperature in natural conditions. This information was then connected to the survival rates and reproductive success of the damselflies in their natural populations.

The results show that survivorship of these damselflies was high at relatively low temperatures, 15 - 20 C °. The reproductive capacity, on the other hand, was higher at temperatures between 20 and 30 C °, depending on the species.

“There is, therefore, a temperature-dependent conflict between survival on one hand and the ability to reproduce on the other”, says Erik Svensson, professor at the Department of Biology at Lund University, who led the study.

An insect is sitting in a tube. Collage of infrared photos.
Infrared camera images of damselfly A series of infrared camera images shows the increasing body temperature of a damselfly