By Marg Land
It seems that lately, everyone has been in a tizzy about bees and neonicotinoid pesticides.
Recently, I received a short news brief from the Associated Press informing me that the European Union’s commissioner for health and consumer policy – Tonio Borg – has proposed restricting the use of three neonicotinoid pesticides – clothianidin, imidacloprid and thiametoxam – from use on a wide variety of crops, including sunflowers, rapeseed, cotton and maize. The ban is being considered in light of growing concern regarding colony collapse disorder (CCD), a phenomenon whereby large numbers of honeybees within a colony either die or disappear, and its alleged connection to the growing use of neonicotinoids, a class of pesticide considered one of the best selling in the world.
Not long after reading that brief, I received a newsletter article from the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) entitled Taking Steps Toward Reducing the Risk to Pollinators.
“In the spring of 2012, coinciding with corn planting, there were approximately 200 incidents of what was likely acute bee poisoning of honeybees in Ontario,” stated the article, written by field crop entomologist Tracey Baute and crop specialist Greg Stewart. “Representatives from the Ministry of Environment, the Pest Management Regulatory Agency and OMAFRA investigated the affected bee hives, taking bee samples for residue analysis by the PMRA.”
According to initial lab results, “pesticides used on treated corn seed may have contributed to at least some of the 2012 spring bee losses that occurred in Ontario, however, there is still additional information being collected.”
It was also noted there was no evidence of off-label use of pesticides by growers.
Final results of the tests have not been released but the PMRA analysis did show the presence of clothianidin, one of the neonicotinoids currently being considered for use restriction in the EU.
And then, just a few weeks ago during the Lower Mainland Horticulture Improvement Association’s Grower Short Course, held in Abbotsford, B.C., I listened as B.C.’s provincial apiculturist Paul van Westendorp provided a summary of the concerns being voiced around the world regarding the use of neonicotinoids and decreases in pollinator populations, including a brief history of actions taken to date.
Back in 2001, he explained, a group of beekeepers in France noticed that many of their healthy bee colonies began to dwindle and die-off. The interesting thing was, these die-offs were being observed in hives near corn and potato fields.
“What made it interesting is that neither corn nor potato is an important pollinating food source for the bees, either as a pollen source or a nectar source,” explained van Westendorp. “Bees only visit these plants incidentally.”
Not long after, reports began to come in from all over Europe about similar happenings.
“This was really the first claims saying neonicotinoids were responsible for the declines,” he added.
Around the same time, Canada was considering expanding the label registration of neonicotinoids for a number of crops, said van Westendorp. Therefore, a great amount of research was conducted in North America examining the impact of the pesticide on pollinators.
“A huge amount of research was done, a lot of research papers were reviewed and re-examined to determine was there any possible link,” said the B.C. apiculturist. “And all the answers were no.”
Meanwhile colony collapse disorder continued.
Then in 2010, Dr. Henk A. Tennekes, a Dutch toxicologist, published a research paper suggesting the structure of pesticide risk assessment systems used by regulators could be flawed.
“They [regulators] were approaching it on the basis of acute toxicity that these chemicals might have on insect pollinators,” explained van Westendorp.
Dr. Tennekes’ hypothesis was that the real impact of neonicotinoids should be assessed based on chronic exposure at sub-lethal levels.
“This really changed the entire discussion because now suddenly an awful lot of researchers started to realize that perhaps they had been looking at neonicotinoids in the wrong fashion,” said van Westendorp.
According to studies where insects were exposed to sub-lethal levels of neonicotinoids, behavioural changes involving nesting, homing abilities, disease resistance and reproduction were observed.
“As of June 2012, the PMRA made the announcement that it is reassessing the three most commonly used neonicotinoids,” said van Westendorp. “The EPA came out in December with the intent of doing a thorough overview of the entire group of neonicotinoids with a special emphasis on the possible effects these chemicals have on pollinators.”
What does this mean for growers? While reassessment of neonicotinoids is being done in Canada – which is expected to take several years – the insecticides can still be used as registered. And for beekeepers? Keep a close eye on your hives and be aware of what might have been used on the crop currently being pollinated and any adjacent crops, including seed treatments.
Good luck and have a safe 2013 season.