US biologists from the University of Texas at Arlington have carried out research focusing on the Great Basin and Sierra Nevada mountains, a region home to over 200 species of lepidoptera.

Published in the journal Oecologia, the study shows that climate change and extreme events (storms, forest fires, drought) are disrupting flowering periods and depriving butterflies of food sources.

While the threat to butterflies has been demonstrated before, few studies have looked at the impact of climate change on their food sources.

The scientists’ research covered 21 years, using butterfly samples collected from various sites throughout the study region, as well as specimens from the University of Nevada, Reno Museum of Natural History.

The aim was to track the potential effects of direct and indirect changes in precipitation, temperature, monsoons and forest fires on the interactions between plants and butterfly pollination.

The researchers found a decrease in the pollen richness associated with butterflies in the sites studied, as well as an increase in the abundance of pollen grains from drought-tolerant plants, particularly over the last 10 years.

The global rise in temperatures, as well as the intensity and frequency of precipitation and forest fires, have also had a negative impact on pollen diversity.

“Our findings have important implications for understanding plant–pollinator interactions and the pollination services affected by global warming,” the study authors conclude.

Butterfly survival isn’t just threatened in the United States. According to a 2022 report by the French Biodiversity Agency (OFB), of the 301 species of butterfly found in mainland France, 200 have disappeared from at least one département since the last century.

In total, this represents 66% of species. And according to the European Environment Agency, half of all grassland butterflies have disappeared from Europe in the space of 20 years.