On the Edge of Survival: Are Tropical Insects Running Out of Time in a Warming World?

By Vaishnavi Chaturvedi P, Arpit Chaturvedi P and Santhosh Naik G

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Insects form the backbone of global biodiversity, with nearly 70% of species occurring in tropical regions. They play vital roles in pollination, nutrient cycling, and maintaining ecological balance. However, despite their importance, the response of tropical insects to rising temperatures remains poorly understood. As climate change intensifies, increasing temperatures, extreme weather events, and habitat degradation are placing unprecedented stress on insect populations. Being ectothermic, insects are highly sensitive to environmental temperatures, and even small increases can have severe physiological consequences. Contrary to earlier assumptions, emerging evidence suggests that many tropical insects are already living close to their thermal limits.

To address this gap, Holzmann and coworkers (2026) conducted a large-scale study examining approximately 2,300 insect species (~8,000 individuals) across elevational gradients in Africa and South America. The results revealed that thermal tolerance does not increase proportionally with environmental temperature but instead approaches an upper limit in tropical lowlands. While high-elevation insects exhibited some capacity to adjust to warming, lowland species showed limited or even negative responses to heat stress. This indicates that many tropical insects are already operating near their maximum heat tolerance, leaving little scope for further adaptation.

Fig. 1. A model illustrating altitudinal variation in insect thermal adaptability (AI generated image)

This limited adaptive capacity is closely linked to biological plasticity which is the ability of organisms to adjust their physiology without genetic change. High-elevation insects demonstrated modest improvements in heat tolerance after sublethal exposure, whereas lowland species showed little or no improvement, suggesting that their stress-response systems may already be functioning at maximum capacity. This reduced plasticity makes them particularly vulnerable to additional warming.

At the molecular level, thermal tolerance is strongly constrained by protein stability. Proteins are essential for cellular function but are highly sensitive to temperature. Using genomic data from 677 insect species, researchers found that the melting temperature (Tm) of the most heat-sensitive proteins averages around 42.15°C, closely matching the critical thermal maximum (CTmax) of insects. This indicates that thermal limits are fundamentally determined by protein structure, making rapid evolutionary adaptation difficult.

Evolutionary history further restricts thermal adaptability. Closely related species share similar thermal limits, reflecting strong phylogenetic constraints. Among insect orders, Diptera (flies) generally shows lower heat tolerance, while Hymenoptera (ants, bees) and Orthoptera (grasshoppers) exhibit relatively higher tolerance. However, these differences occur within a narrow range, with an evolutionary optimum near ~42°C, suggesting a hard upper boundary shaped by stabilizing selection.

Fig. 2. Thermal denaturation and variation in thermotolerance across insect orders (AI generated image)

The implications of these findings are particularly concerning under future climate scenarios. In tropical lowland regions, especially the Amazon, current temperatures are already close to critical thresholds. In fact, present-day surface temperatures can induce heat coma within minutes under direct sunlight. Projections indicate that up to 52% of surface temperatures and 38% of air temperatures may exceed survivable limits, posing a severe threat to insect communities. Although insects may seek refuge in cooler microhabitats such as shaded vegetations, these refuges are rapidly declining due to deforestation and habitat loss.

In addition to heat stress, tropical insects are vulnerable to cold extremes. Despite living in warm climates, many species have limited tolerance to sudden temperature drops. While thermal tolerance ranges remain relatively constant, high-elevation insects can enhance cold tolerance through cold hardening, whereas lowland species lack this ability. Increasing climate variability, including unexpected cold waves, further intensifies this dual stress. The consequences of insect decline are far-reaching. Insects are essential for ecosystem functioning, supporting pollination, decomposition, and food webs. Their loss could disrupt ecological stability and threaten agricultural productivity and food security. To mitigate these risks, conservation strategies must focus on preserving forest ecosystems that provide thermal refuges, maintaining habitat connectivity to enable range shifts, and addressing climate change at a global scale. Protecting these small yet critical organisms is essential for sustaining biodiversity and ecosystem resilience.

In conclusion, tropical insects are far less resilient to heat than previously assumed. Their thermal limits are shaped by physiological, molecular, and evolutionary constraints, leaving little capacity for rapid adaptation. As global temperatures continue to rise, many species may soon exceed their survival thresholds, making urgent climate action and habitat conservation essential for their persistence.

For more details, please refer:

Holzmann, K. L., Schmitzer, T., Abels, A., Čorkalo, M., Mitesser, O., Kortmann, M., Alonso-Alonso, P., Correa-Carmona, Y., Pinos, A., Yon, F., Alvarado, M., Forsyth, A., Lopera-Toro, A., Brehm, G., Keller, A., Otieno, M., Steffan-Dewenter, I., & Peters, M. K. (2026). Limited thermal tolerance in tropical insects and its genomic signature. Nature, 651, 672–678. https://doi.org/10.1038/s41586-026-10155-w

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About the authors:

Vaishnavi Chaturvedi P, Research Scholar, Department of Entomology, Dr. Rajendra Prasad Central Agricultural University Pusa (Samastipur), Bihar, India 848125.

Email: vaishnavisvc1@gmail.com

Arpit Chaturvedi P, Research Scholar, Department of Entomology, Dr. Rajendra Prasad Central Agricultural University Pusa (Samastipur), Bihar, India 848125.

Email: Arpitchaturvediac.9pp@gmail.com 

Santhosh Naik G, Research Associate, Division of Entomology, ICAR- Indian Agricultural Research Institute, New Delhi, India 110012.

Email: santhoshckm55@gmail.com

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