Friday, 30 June 2017

New research warns, the world’s most widely-used family of insecticides, can decimate bee populations.

 But chemical companies, who helped fund the study, believe it provides a loophole they can use to support their case for their continued use.
by Larry Powell
Bumblebees forage on chives in a Canadian garden. PinP photo.
It was the first, large-scale field trial of its kind in Europe. It looked at ways that two kinds of “neonics,” (clothianidin and thiamethoxam) may affect tame honeybees and two wild bee species in the UK, Hungary and Germany. 

Its findings were published yesterday in the journal, Science.

In the UK and Hungary, honeybee colonies located near crops of “oilseed rape” (also called “Canola”) treated with clothianidin and planted the previous year, had almost one quarter (24%) fewer workers in the spring. (Thiamethoxam didn’t hurt them.)

As Richard Pywell, an ecologist at the UK-based Centre for Ecology & Hydrology,  puts it, “We’re showing significant negative effects at critical life-cycle stages, which is a cause for concern.” (Pywell co-authored a paper resulting from the field trial.)

But, in an unexpected twist, the results also found that the German bees seemed to have come through the trial without negative effects! 

Pywell believes he knows why. Wildflowers growing near the German fields may have kept those colonies healthier and more resistant to the toxic effects of the chemical than those in the other two countries.

A Canadian scientist, Prof. Nigel Raine of the University of Guelph, (R), believes the writing should now be on the wall as to the harm “neonics” can do to pollinators. 

"Whilst results from this large-scale study report varying impacts…the overall picture points towards appreciable negative impacts on these important pollinators across the time course of this study.  It is concerning that bumblebee colonies produce fewer queens, and solitary bees (Osmia bicornis) produce fewer offspring, where higher levels of exposure to neonics were found. These bees represent the basis for the next generation of these species in the following year, and fewer of these important individuals could have significant impacts on population size and persistence."

Prof. Raine is also worried that researchers found residues of the culprit chemical, clothianidin, in crops grown from what was supposed to be “clean” or “control” seed. “This suggests that residues from previous agricultural applications could still be affecting bees in the field even several years after the EU moratorium (of 2013) on these active ingredients came into effect. It provides additional support for restrictions on the use of neonicotinoids based on concerns about impacts on insect pollinator health. Such regulations must balance the benefits of using insecticides to control damaging crop pests appropriately against the unintended costs of harming beneficial insects exposed to these chemicals in agricultural landscapes. Pollinators are responsible for one in three mouthfuls of food we eat, so safeguarding their health is something we should all care deeply about.”

Another scientist shares Prof. Rain’s sentiments. In the words of David Goulson, Professor of Biology at the University of Sussex, “In the light of this new study, continuing to claim that use of neonicotinoids in farming does not harm bees is no longer a tenable position.”

In any case, few can fault this latest effort for not being thorough or extensive. It cost £2.8 million, lasted for two years and covered 33 sites in the three countries involved.

But it has also provided at least some perceived ammunition for the chemical industry to cling to its position that its products are safe for pollinators. Here’s what Dr Peter Campbell, Senior Environmental Risk Assessor at Syngenta (which manufactures and sells related products) has to say following publication of these new field trials.

This demonstrates that neonics can be used safely or even with benefit to bees under certain circumstances e.g. such as reported in Germany.”

Meanwhile, Health Canada is considering whether to take another member of the "neonic" family, imadacloprid, off the market. It has delayed its decision on the matter.



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