Neonics ban wouldn’t immediately reverse bee declines: review

bees
(Photo courtesy ARS/USDA)

Any bid to ban the use of neonicotinoid pesticides in farm crops likely wouldn’t bring bee populations back immediately, according to a new review of the issue calling for “evidence-based” debate.

The review was published Wednesday in Proceedings of the Royal Society by 10 scientists including University of Guelph professor Nigel Raine, the school’s Rebanks Family chair in pollinator conservation.

The scientists’ paper is billed as a “restatement” that “aims to clarify what is known about these insecticides to support coherent policy and practice recommendations.”

“We have tried to be policy-neutral though (we) are aware that complete neutrality is impossible,” they wrote.

“This paper provides a balanced and accessible summary of both the strengths and weaknesses of research in this area to facilitate evidence-based discussion and policymaking,” Raine said in a university release.

“The causes of global bee and other key pollinator declines are likely the result of multiple factors including loss of suitable habitat, parasites and diseases, invasive species, adverse weather conditions and agricultural intensification, including the use of agrochemicals such as pesticides.”

The new review, Raine said, “will be a useful tool for policymakers and regulators to help them assess the scientific evidence on this potentially confusing issue.”

The paper discusses insecticide amounts in treated plants and in pollinators, how the “neonics” affect individual bees and other pollinators, and the insecticides’ impact on colonies and populations.

In any case, scientists need to figure out how to stop pollinator decline, said Raine, whose research chair is the first of its kind in Canada.

“Roughly one in three mouthfuls of food we eat are reliant on insect, and primarily bee, pollination. This includes the majority of fruits and vegetables, coffee and others, so losing pollinators will increase the price of these goods or make it harder to grow them in some parts of the world. Ultimately, if pollinator populations continue to decline, we may lose the ability to grow these crops altogether.”

“Limited evidence”

The paper also notes banning neonicotinoids would likely not immediately reverse declines. Pollinator numbers were falling before these pesticides were introduced in the 1990s, the authors noted.

Plus a ban could discourage farmers from growing crops needed by pollinators, the authors said, calling for more research on the impacts of neonics.

“If neonicotinoids are not available, then farmers will have to choose alternative pest-management strategies, alternative crops or accept greater losses,” the scientists wrote. “The impact upon pollinators of withdrawing neonicotinoids will be greatly influenced by such choices.

“Farmers’ likely strategies when faced with restrictions on the use of neonicotinoids are being researched, but there is currently only limited evidence to guide policymakers in what changes to expect.”

The concentrations of neonics found in pollen and nectar are “nearly always some way below those that would cause immediate death” in bees, the scientists wrote, but “the great problem is to understand whether the sublethal doses received by pollinators in the field lead to significant impairment in individual performance, and whether the cumulative effect on colonies and populations affects pollination in farmed and non-farmed landscapes and the viability of pollinator populations.”

Published literature on neonics, meanwhile, is “a small fraction of the evidence that has been collected,” the scientists added. Detailed environmental risk assessments are done for product registration, including “substantial evidence” on toxicity, or lack thereof, to non-target organisms such as honeybees.

But the data generated in such studies “are not typically in the public domain,” the scientists wrote, not mainly for reasons of “proprietary intellectual property” but because the information would be “commercially advantageous to a competitor in registering (a neonic) compound when it is out of licence.”

The authors, in their paper, wondered aloud whether registration rules “might be amended to allow this type of data to be published, a clear public good, without disadvantaging companies that had invested in its collection.” — AGCanada.com Network

 

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