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Farm pesticides killing twice as many bees than first thought, study finds

‘Synergistic effect’ of using pesticides together could accidentally kill more bees, experts warn

Zaina Alibhai
Friday 06 August 2021 15:16 BST
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((Photo: Getty Images))

Farmers are being sold agricultural pesticides that can kill twice as many bees, according to an analysis of 90 studies which delved into the impact of environmental pressures.

The factors - many of which are a consequence of human activity - include land use and climate change, with intensive agriculture and pest control playing a significant role.

Pesticides in particular were found to have put physiological and nutritional stress on bees, with the “cocktail”of agrochemicals they encounter in intensively-farmed environments posing a risk to their populations.

Because of this, the researchers believe commercial formulas should require their own licences.

Speaking on BBC Radio 4’s ‘Inside Science’ programme, lead Dr Harry Siviter said: “We should really consider the interaction between those chemicals.

“We don’t continue to monitor pesticides once they’re licensed for use, so we’re proposing post-licensing observations.”

Dr Siviter, who led the study, noted that from the 356 interactions the team of researchers studied, bees colonies exposed to agrochemicals were more likely to die.

“If you have a honey bee colony exposed to one pesticide that kills 10 per cent of the bees, and another pesticide that kills another 10 per cent, you could expect if those effects were additive, 20 per cent of the bees would be killed,” he explained.

However, a “synergistic effect” could bring the figure up to between 30 and 40 per cent mortality, he said.

The team’s report read: “Subgroup analysis of bee mortality revealed strong evidence for synergy when bees were exposed to multiple agrochemicals at field-realistic levels, but interactions were not greater than additive expectations when bees were exposed to parasites and/or nutritional stressors.”

Their analysis also found stark differences in the way various parasites groups impacted bee populations.

The findings coincide with a petition launched by Dave Goulson, a professor of biology at the University of Sussex, calling for the ban of pesticides.

He argued the agrochemicals not only threatened bees and other wildlife, but posed a potential catastrophe to humans too as many were carcinogens and or neurotoxins.

Professor Goulson called on the government to ban pesticides in all 22 million gardens, park, road verges and other green spaces.

He said: “There is simple no need to spray poisons in our streets, parks and gardens for cosmetics purposes where they harm bees and other wildlife, and post a risk to human health.

“Safe alternatives are available, where necessary.”

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