Extreme Heat Could Kill Half of Tropical Forest Insects

A new scientific study warns that climate change could push many tropical insects beyond the temperatures they can survive. Research published in the journal Nature, March 4, 2026 suggests that up to half of insect species in the Amazon may face potentially lethal heat exposure if global warming continues in the coming decades.

The findings come from a large-scale study examining about 2,300 insect species collected from tropical ecosystems in East Africa and South America. Scientists measured the insects’ upper thermal limits and analyzed genomic data to understand the biological factors that determine their tolerance to heat.

The results indicate that many tropical insects already live close to their physiological heat limits. Even a modest increase in temperature could push some species into levels of heat stress that cause paralysis or death.

How Many Insects Could Be Affected

Insects represent the most diverse group of animals on Earth. Roughly 70 percent of known animal species are insects, and the majority live in tropical regions. Because of this enormous biodiversity, climate-driven impacts on insects could have far-reaching ecological consequences.

According to the study, future temperatures in lowland Amazon regions may reach levels capable of triggering critical heat stress for roughly half of the insect communities examined.

“If global ecosystems continue to warm unchecked, projected future temperatures could cause critical heat stress for up to half of the insect species in the Amazon,” said lead researcher Kim Lea Holzmann of the University of Würzburg.

The figure highlights the potential scale of the threat, particularly since millions of insect species remain undescribed by science.

What Heat Stress Does to Insects

Extreme heat does not always kill insects instantly. However, high temperatures can cause severe physiological disruption that ultimately threatens their survival.

Laboratory experiments and field observations show that insects may enter a condition known as heat coma when exposed to temperatures beyond their tolerance. In this state, the nervous system and motor functions shut down, leaving the insect unable to move or feed and making it highly vulnerable to death.

Heat can also damage proteins within cells. The study found that protein stability is closely linked to how well insects can tolerate high temperatures. When temperatures rise too much, certain proteins lose their structure and can no longer perform their biological functions.

Marcell Peters, an ecologist at the University of Bremen and co-author of the study, explained that these biological constraints suggest insects may struggle to adapt quickly enough to rapid climate warming.

The fundamental characteristics of heat tolerance, he said, appear deeply embedded in insect biology and cannot easily shift within a short evolutionary timeframe.

Tropical Lowlands Are at Highest Risk

The research also revealed major differences between insects living in tropical lowlands and those inhabiting higher elevations.

Insects found in mountainous regions showed a greater ability to temporarily increase their heat tolerance. In contrast, many species living in hot tropical lowlands displayed almost no capacity to adjust to higher temperatures.

This makes already warm ecosystems particularly vulnerable to climate change.

Besides the Amazon basin, similar risks may occur in parts of East African savannas and other tropical rainforest regions across South America. These landscapes are not only naturally warm but also among the most biologically diverse areas on the planet.

As global temperatures rise, insects in these regions may increasingly experience heat levels that exceed their biological limits.

Why Tropical Insects Are More Vulnerable

Many tropical insects evolved in environments where temperatures remain relatively stable throughout the year. As a result, they tend to have narrower thermal tolerance ranges compared with insects in temperate regions, which regularly experience seasonal temperature fluctuations.

The study found that insect heat tolerance does not simply increase in proportion to environmental temperature. Instead, it tends to plateau once species evolve in very warm climates.

This means insects living in already hot environments may have little room left to adapt if temperatures continue to rise.

Insects play crucial roles in nearly every terrestrial ecosystem. They pollinate many plant species, help decompose organic matter, recycle nutrients in soils, and serve as a primary food source for birds, amphibians, reptiles, and small mammals.

A widespread decline in insect populations caused by heat stress could trigger cascading ecological effects. Plants that depend on insect pollination may struggle to reproduce, nutrient cycling in soils could slow, and animals that rely on insects for food may lose a critical energy source.

Researchers emphasize that rising global temperatures could place enormous pressure on insect populations, particularly in tropical regions where biodiversity is highest. (Sulung Prasetyo)