Neonicotinoids pose risks to bees in three ways, says a researcher. But farmers and the ag industry can manage the biggest risks, he told delegates at the International Rapeseed Conference in Saskatoon this past summer.
Dr. Udo Heimbach researches pesticide use and environmental effects with Germany’s Julius Kuhn-Institut. He presented research studying neonics’ effects on bees during the conference.
One risk lies in the liquid plants give off from leaf edges, known as guttation. Bees haul water for everything from larval food to diluting honey, Heimbach explained. Guttation liquid is one water source for them.
And if bees collect droplets containing neonics, those individual bees die, he said.
“Very simply, there is a risk. But with all that we saw, there’s no unacceptable effect on honeybee colonies if there is sufficient water available,” said Heimbach. Beekeepers can avoid problems by making sure hives aren’t bordering fields of emerging maize or oilseed rape, he said. Researchers also studied the effect of neonic residue in pollen and nectar on honeybees, bumblebees, and solitary bees. They did find low levels of clothianidin in the pollen and nectar of winter oilseed rape in 2014. Heimbach said there was also some residue in beehives eight weeks after the bees were first exposed to the neonic during flowering.
“So there is clearly an exposure,” he told delegates. But they didn’t see any significant effect on bees during the 2014 trials, he said. The 2015 trials were being finalized, but they hadn’t seen effects so far that year, either, he said. Heimbach did caution that the honeybee data was more reliable than data for bumblebees and other bees.
Heimbach warned against assuming those results would hold for a summer oilseed. A Swedish study found higher residue levels in summer oilseeds than winter oilseeds, he said. Seeding rate, cropping period, and plant biomass all affect residue levels, Heimbach explained.
Two peer-reviewed research papers have found low levels of neonic residue from Canadian canola. Both included beehives set in clothianidin-treated and control canola fields. In both studies, the seed treatment was applied at the recommended rate.
One study found no more than two parts per billion (ppb) of clothianidin in pollen samples. The other found residue no higher than 2.59 ppb in pollen, nectar and honey samples. Previous research benchmarked 20 ppb of clothianidin as the concentration that harms bees.
Neither study found differences between control and treated colonies in honey yield, winter survival, bee mortality, brood development, or other measures.
The risks of residue in pollen nectar have been known for 20 years, Heimbach said in an interview. “This is nothing new. And this is nothing big. But we can really create problems with dust.”
Before the European Union (EU) restricted neonics, most oilseed rape was seed-treated in Germany. In 10 years, no beehive poisonings had been linked to neonics used for oilseed rape, Heimbach’s research states. But in 2008, 12,000 beehives were damaged in Germany. The culprit was abrasion from seed treatments and drifting dust during maize seeding, according to Heimbach’s research.
To protect bees, farmers need to cut abrasion from seed treatments, Heimbach said. Dust should contain low levels of the active ingredient, he added. And farmers should sow in ways that prevents dust from drifting into neighbouring areas, he added.
In 2014, Canada’s Pest Management Regulatory Agency (PMRA) restricted seed flow lubricants to reduce bee exposure to dust. Graphite and talc are no longer permitted in Canada. Currently Bayer CropScience’s “Fluency Agent” is the only approved lubricant.
There has been a “considerable effort” put into improving seed treatments in Germany, Heimbach said; active ingredient levels in the dust have dropped. Dust abrasion of oilseed rape has also improved, Heimbach’s research states.
The European Union (EU) banned several neonics in crops that attract bees for at least two years. The first oilseed crop after the ban was sown in the fall of 2014. German farmers sprayed five times as much pyrethroid as previous years, Heimbach told delegates.
Increased spraying would not have a “positive effect” on the environment, he noted. More spraying also means more selection pressure on pyrethroid-resistant cabbage stem flea beetles, he said. The neonic ban also means farmers have no control for cabbage root flies, said Heimbach.
Germany’s oilseed rape growing area has also dropped since 2013, he said, and he suspected it would keep dropping.
The EU isn’t the only jurisdiction with neonic restrictions. The Ontario government has set regulations that will require farmers to take integrated pest management courses and complete pest assessments before buying neonic-treated seed for any corn or soy acres, after 2016’s growing season. Eventually professional pest advisors will need to complete the pest assessments.
Heimbach said the Canadian ag industry should try to work with regulators and look into improvements immediately. “They should be open to the regulators, sharing what they have and what they did.”
Whether or not the current neonic restrictions will stick in the EU remains to be seen.
“Of course, I can’t predict the outcome of that because there’s always a risk. And you always have some effects. You never have nothing.”