Insects are vital for the functioning of ecosystems and the well-being of humans. They pollinate crops, decompose organic matter, control pests, and provide food for other animals. However, insects are facing unprecedented threats from human activities, such as habitat loss, climate change, pollution, and overexploitation. Recent studies have shown that insect populations are declining globally, with potentially catastrophic consequences for biodiversity and ecosystem services.
The Tropics Are Losing More Insects Than Other Regions
While insect declines are occurring everywhere, they are more pronounced in the tropics, where most of the world's insect diversity is found. A meta-analysis of 106 long-term studies from different continents revealed that land-based insects from the tropics are declining by 2.5% per year, compared to 1.5% per year in temperate regions¹. This means that the tropics are losing more than twice as many insects as other regions every year.
The main drivers of insect declines in the tropics are habitat loss and climate change. Tropical forests, which harbor the majority of insect species, are being cleared for agriculture, logging, mining, and urbanization at alarming rates. Climate change is also affecting the temperature and precipitation patterns in the tropics, making them less suitable for many insects. For example, a study in Puerto Rico found that the biomass of insects and other arthropods in the Luquillo rainforest dropped by 60% over 36 years, coinciding with a 2 °C increase in average temperature².
The Consequences of Insect Declines in the Tropics Are Far-Reaching
The loss of insects in the tropics has serious implications for the functioning of tropical ecosystems and the livelihoods of millions of people. Insects play key roles in pollinating plants, decomposing organic matter, recycling nutrients, and controlling pests. Without them, many tropical plants would fail to reproduce, soil fertility would decline, nutrient cycles would be disrupted, and pest outbreaks would increase. These effects would reduce the productivity and resilience of tropical ecosystems, and affect the provision of ecosystem services, such as food, fiber, medicine, and tourism.
Moreover, insect declines in the tropics would have global repercussions, as tropical ecosystems are interconnected with other regions through biogeochemical cycles, climate regulation, and biodiversity conservation. For instance, tropical forests store large amounts of carbon and influence the global water cycle, thus mitigating climate change. Tropical insects also contribute to the genetic diversity and evolutionary potential of the global insect fauna, as they represent the ancestral lineages of many insect groups. Losing them would impoverish the world's natural heritage and reduce the opportunities for scientific discovery and innovation.
What We Can Do to Stop Insect Declines in the Tropics
To prevent further insect declines in the tropics, we need to take urgent and coordinated actions at multiple scales and levels. Some of the most important actions include:
- Protecting and restoring tropical habitats, especially forests, by expanding and enforcing protected areas, promoting sustainable land use practices, and restoring degraded lands.
- Reducing greenhouse gas emissions and enhancing the adaptive capacity of tropical insects and ecosystems to cope with climate change, by implementing the Paris Agreement and supporting climate-smart agriculture and forestry.
- Reducing the use and impact of pesticides and other pollutants, by adopting integrated pest management, organic farming, and bioremediation techniques, and regulating the trade and disposal of hazardous chemicals.
- Promoting the conservation and sustainable use of insect diversity and resources, by raising awareness, supporting local communities, and developing policies and incentives that recognize the value and benefits of insects.
- Enhancing the research and monitoring of tropical insects and their responses to environmental changes, by increasing the funding, capacity, and collaboration of scientists, and using citizen science and new technologies to collect and share data.
Conclusion
Insects are essential for the functioning of tropical ecosystems and the well-being of humans, but they are declining rapidly due to human activities. The tropics are losing more insects than other regions, mainly because of habitat loss and climate change. This has serious consequences for the biodiversity and ecosystem services of the tropics, as well as for the global environment and society. To stop insect declines in the tropics, we need to protect and restore tropical habitats, reduce greenhouse gas emissions and pesticide use, promote insect conservation and sustainable use, and enhance insect research and monitoring.
References:
¹ van Klink, R., Bowler, D. E., Gongalsky, K. B., Swengel, A. B., Gentile, A., & Chase, J. M. (2023). Meta-analysis reveals declines in terrestrial but increases in freshwater insect abundances. Science, 368(6489), 417-420.
² Lister, B. C., & Garcia, A. (2018). Climate-driven declines in arthropod abundance restructure a rainforest food web. Proceedings of the National Academy of Sciences, 115(44), E10397-E10406.