The world’s most popular pesticide probably killed England’s wild bees

Death by pesticide.
Death by pesticide.
Image: Reuters/Lisi Niesner
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Since around 2002, farmers in the English countryside have been using neonic insecticides to protect their abundant oilseed crops spanning 8.2 million hectares. Now, scientists are linking the chemicals, also called neonicotinoids, to the death of half of the wild bee population in the country, according to a new study published in Nature Communications.

Many bee species forage on the bright yellow oilseed crops that grow in the UK. The seeds for these crops are coated with neonicotinoids upon planting. Then, the chemical systematically expresses itself in all cells of the growing plant. Bees that feed on the plant ingest the chemical through the pollen or nectar.

Researchers studied 62 species of wild bees across England from 1994 to 2011. Over the last nine years, the decline in population size was three times worse among species that regularly fed on oilseed plants compared to others that forage on different floral resources, the study found. Five species showed declines of 20% or more, with the worst-hit species experiencing a 30% drop in its population.

In Europe, 9.2% of the continent’s almost 2,000 bee species are facing extinction, according to one assessment. But until now, it’s been hard to quantify how seriously chemicals have impacted bees. “Pesticides and beekeeping have been butting heads for 50-plus years,” David R. Tarpy, a professor at North Carolina State University’s department of entomology, told Quartz.“[Pesticides are] clearly part of the equation, but we don’t know the relative magnitude.” Habitat loss and mites also have a hand in the declining bee populations but the latest findings is hard to ignore. Especially since neonic pesticides may also harm birds, butterflies, and water-borne invertebrates, according to Mother Jones.

The research, led by the Centre for Ecology & Hydrology, builds on findings from shorter, smaller-scale studies that have previously outlined the risks of using neonic pesticides, which sparked a European Union moratorium on the use of select pesticides. (The ban has since been suspended after a UK’s National Farmers Union challenge.) In the US, too, the government has not fully declare an end to the chemical, but it did propose pesticide-free zones for the bees to thrive. The European Food Safety Authority is currently in the midst of assessing scientific evidence about neonicotinoids.

The researchers believe their findings offer clear guidance: “While short-term laboratory studies on honeybees and bumblebees have identified sub-lethal effects, there is no strong evidence linking these insecticides to losses of the majority of wild bee species,” they wrote in the study. “Our results suggest that sublethal effects of neonicotinoids could scale up to cause losses of bee biodiversity. Restrictions on neonicotinoid use may reduce population declines.”

However, as Nature reports, even a complete neonicotinoid ban won’t solve the bee die-off problem entirely:

The problem for policymakers is how to control crop pests while encouraging a healthy diversity of pollinators such as bees, [ecologist Ben] Woodcock says. “You can’t just say, ‘As long as we save the bees, everything else can go to hell’,” he says. “We also need to consider the effects of whatever pesticide is used instead of neonicotinoids when those are banned.”