“Current assessments of heat tolerance in insects such as moths, flies and beetles paint a different and at the same time alarming picture,” says study author Kim Holzmann, Ph.D., researcher and chair of the Department of Animal Ecology and Tropical Biology at the Julius-Maximilians-Universität Würzburg (JMU).
This study suggests that insects do not simply adjust their heat tolerance to suit their environment. “While high-altitude species can increase their heat tolerance, at least in the short term, many lowland species have very little of this ability,” Holzman explains.
Climate change threatens the key role of ecosystems
The survey results are natureindicating that tropical insects have a limited ability to adapt to a warming climate. Rising temperatures could significantly disrupt insect populations, especially in regions with the greatest biodiversity on Earth, said study author Dr. Marcel Peters, an animal ecologist at the University of Bremen.
“Increasing temperatures can have a major impact on insect populations, especially in regions with the highest biodiversity in the world,” Peters says. “Insects play central ecosystem functions as pollinators, decomposers, and predators, so they pose a threat that has far-reaching impacts across ecosystems.”
Protein stability limits thermal adaptation
The researchers also found large differences between groups of insects in how well they tolerate heat. These changes appear to be related to the structure and thermal stability of proteins in the body.
“These traits are relatively conserved within the insect evolutionary family tree and can only be modified to a limited extent,” Peters explains. “This result suggests that the fundamental trait of thermotolerance is deeply rooted in biology and cannot be quickly adapted to new climatic conditions.”
Holtzman said the outlook for the Amazon region is particularly concerning. “If Earth’s ecosystems continue to warm unabated, projected future temperatures will result in significant heat stress for up to half of the insect species that live there,” JMU biologists say.
Large-scale study investigating heat tolerance of 2,000 species
Insects make up approximately 70% of all known animal species, and the majority of them live in tropical regions. Still, scientists still know little about how well tropical insects cope with rising temperatures.
One reason for this is the lack of experimental data on temperature tolerance and the limited research available for many insect groups. To address this gap, an international team of scientists conducted a study with support from the German Research Foundation.
Researchers examined the temperature tolerance limits of more than 2,000 insect species. Field data were collected in 2022 and 2023 at various elevations in East Africa and South America, including cool montane forests, hot rainforests, and lowland savannahs.
In addition to measuring temperature limits, the team analyzed the genomes of many species. This allowed them to investigate protein stability and gain insight into why certain insect groups can cope with heat better than others.
