A new study from the University of North Carolina at Chapel Hill shows that insect populations are rapidly declining even in relatively undisturbed landscapes, raising concerns about the health of ecosystems that depend on them.
Keith Sockman, associate professor of biology at UNC-Chapel Hill, quantified the abundance of flying insects during 15 seasons between 2004 and 2024 on a subalpine meadow in Colorado, a site with 38 years of weather data and minimal direct human impact. He discovered an average annual decline of 6.6% in insect abundance, amounting to a 72.4% drop over the 20-year period. The study also found that this steep decline is associated with rising summer temperatures.
"Insects have a unique, if inauspicious position in the biodiversity crisis due to the ecological services, such as nutrient cycling and pollination, they provide and to their vulnerability to environmental change," Sockman said. "Insects are necessary for terrestrial and fresh-water ecosystems to function."
The findings address a critical gap in global insect research. While many reports of insect declines focus on habitats altered by human activity, few examine populations in relatively pristine areas. This study demonstrates that dramatic losses can occur even where direct human impacts are minimal, suggesting climate change may be a key driver.
"Several recent studies report significant insect declines across a variety of human-altered ecosystems, particularly in North America and Europe," Sockman said. "Most such studies report on ecosystems that have been directly impacted by humans or are surrounded by impacted areas, raising questions about insect declines and their drivers in more natural areas."
Sockman emphasizes the urgency of these results for biodiversity conservation: "Mountains are host to disproportionately high numbers of locally adapted endemic species, including insects. Thus, the status of mountains as biodiversity hotspots may be in jeopardy if the declines shown here reflect trends broadly."
This research highlights the need for more comprehensive monitoring of insect populations in a variety of landscapes and adds urgency to addressing climate change. By showing that even remote ecosystems are not immune, the study underscores the global scale of the biodiversity crisis.
The research paper is available online in the journal Ecology at: https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecy.70187
