Long-term study links neonicotinoids to wild bee declines
Wild bees that forage from oilseed rape crops treated with insecticides known as neonicotinoids are more likely to undergo long-term population declines than bees that forage from other sources, according to the findings of an 18-year study.
The new research covered 62 species of bee found in the wild in Britain and found a link between their shrinking populations and the use of neonicotinoid pesticides, according to Reuters.
Neonicotinoids are used worldwide in a range of crops and have been shown in lab-based studies to be harmful to certain species of bee – notably commercial honeybees and bumblebees.
The European Union limited use of the chemicals – made and sold by various companies including Bayer CropScience and Syngenta – two years ago, after research pointed to risks for bees, which are crucial for pollinating crops.
Neonicotinoids were initially licensed for use as a pesticide in Britain in 2002. By 2011, the proportion of UK oilseed rape seeds treated with them was 83 percent, according to the researchers leading this latest study.
Going back to data from 1994 up to 2011, the scientists analyzed how large-scale applications of neonicotinoids to oilseed rape crops influenced bee population changes.
The results found that bees foraging on treated oilseed rape were three times more likely to experience population declines than bees foraging from other crops or wild plants.
Giving details at a briefing in London, Ben Woodcock, who co-led the study, said the average decline in population across all 62 species was 7.0 percent, but the average decline among 34 species that forage on oilseed rape was higher, at 10 percent.
Five of the 62 species studied declined by 20 percent or more, he said, and the worst affected declined by 30 percent.
Woodcock, an ecological entomologist at the Natural Environmental Research Council Center for Ecology and Hydrology, said the findings showed the extent of the impact.
“Prior to this, people had an idea that something might be happening, but no-one had an idea of the scale,” he told reporters. “(Our results show that) it’s long-term, it’s large scale, and it’s many more species than we knew about before.”
H.Z