Insect declines began decades earlier than scientists thought, study finds

For decades, scientists have warned of dramatic insect declines, but new research suggests the crisis began much earlier than researchers realized. Drawing on nearly a century of records, researchers found that butterfly and deadwood beetle diversity in Switzerland has been declining since the 1930s—raising concerns that studies tracking changes over a couple of decades may underestimate the true scale of global biodiversity loss.

In this episode, we examine how intensive agriculture, logging, habitat loss and climate change have shaped insect populations over the last 90 years, why butterflies have struggled to recover while some deadwood beetles have recovered, and what the ‘shifting baseline syndrome’ means for conservation around the world. The findings also offer encouraging evidence that habitat restoration and biodiversity-friendly forest management can help reverse declines for some species.

The study, published in Nature Ecology & Evolution, was led by researchers at Agroscope and involved scientists from the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), the University of Zurich, the University of Basel and other research institutions. The research draws on the remarkable long-term records maintained by Switzerland's info fauna database.

If you've heard warnings about an ‘insect apocalypse,’ this episode explains why scientists now believe the story began decades earlier—and why understanding the past may be the key to protecting biodiversity in the future.

You can find the written article on my webpage.

Key points:

0:52 - Analyzing butterfly and beetle occurrences in Switzerland over the last century

1:55 - Identifying population trends and relating them to changes in the environment and climate

3:13 - Widespread declines in butterflies and beetles through the 1950s

4:16 - Butterfly and beetle declines had different drivers

4:57 - Conservation measures likely stopped the decline

5:27 - Warmer temperatures may benefit heat-loving species

6:17 - Climate change effects on animals and plants are complicated

6:48 - Shifting baselines may hold back conservation efforts

Links to more information:

·       Neff et al., 2026. Ninety-year trends reveal sharpest insect declines in the mid-twentieth century. Nature Ecology & Evolution, 10:1103-1113.

·       Zhou et al., 2023. Long-term insect censuses capture progressive loss of ecosystem functioning in East Asia. Science Advances, 9(5):eade9341.

·       Goulson, 2019. The insect apocalypse, and why it matters. Current Biology, 29(19):R967-R971.

·       Soga and Gaston, 2018. Shifting baseline syndrome: causes, consequences and implications. Frontiers in Ecology and the Environment, 16(4): 222-230.

·       Hallmann et al., 2017. More than 75 percent decline over 27 years in total flying insect biomass in protected areas. PLoS ONE, 12:e0185809.

·       info fauna, Swiss National Fauna Databank.