The findings of a University of Saskatchewan study may affect the fate of insecticide seed treatments in Canada.
The study, which will be published tomorrow in Science, a highly regarded scientific journal, has concluded that imidacloprid is a threat to songbirds.
White crowned sparrows that consumed seeds coated with the insecticide lost weight and the exposure halted their migration, the scientists found.
“We saw these effects using doses well within the range of what a bird could realistically consume in the wild — equivalent to eating just a few treated seeds,” said Margaret Eng, a post-doctoral fellow in the University of Saskatchewan’s Toxicology Centre and lead author of the study.
“Both of these results seem to be associated with the appetite suppression effect of imidacloprid. The dosed birds ate less food, and it’s likely that they delayed their flight because they needed more time to recover and regain their fuel stores.”
Imidacloprid is a neonicotinoid, a class of insecticides used on tens of millions of acres in Canada. Neonics are applied to almost every corn and canola seed in Canada and a portion of soybean seeds.
The study on songbirds comes at a time when Health Canada is making a final decision on the safety of neonicotinoids.
Health Canada has proposed to phase out all agricultural uses of neonics because of evidence showing the insecticides were accumulating in ponds, creeks and other water bodies near agricultural land.
Health Canada has argued the neonics are reducing the population of midges and mayflies in water bodies, potentially harming birds and other animals who depend on those insects for food.
“The department continues to evaluate the potential risks to aquatic insects from the use of neonicotinoids,” Health Canada said earlier this year.
“Current research shows that these pesticides are detected frequently in water bodies at levels that could be harmful to certain aquatic organisms. The department expects to report on its findings at the end of 2019.”
Normally, proposed decisions on pesticides usually become final decisions at Health Canada.
However, data from water testing done in 2017 and 2018 indicated that researchers were finding tiny amounts of neonics in water bodies. Based on that new data, some observers believe Health Canada might back away from its neonic ban.
The U of S study may force Health Canada to think longer and harder about neonicotinoid safety.
“Migration is a critical period for birds, and timing matters. Any delays can seriously hinder their success in finding mates and nesting, so this (study) may help explain, in part, why migrant and farmland bird species are declining so dramatically worldwide,” said Christy Morrissey, A U of S toxicologist and senior author of the study.
U of S and York University researchers studied sparrows at a location in southern Ontario, a stopover during the spring migration.
They exposed the sparrows to small doses of imidacloprid and used a tagging technology to track the impact on the birds. The sparrows’ body composition was measured before and after exposure, and researchers also tracked the birds’ movements in the wild.
“Birds given the higher dose of the pesticide lost six percent of their body mass within just six hours. That one dose also caused birds to stay 3.5 days longer, on average, at the stopover site before resuming their migration, compared to control birds,” the U of S said in a news release.
This is the first study on songbirds exposed to neonicotinoids in the wild.
In 2017, Morrissey and Eng looked at captured sparrows and what happened when the birds ate imidacloprid-coated seeds
The results were similar to the latest study. The scientists concluded the neonic altered the birds’ appetite and sense of direction.
“These chemicals are having a strong impact on songbirds,” Eng said in 2017. “We are seeing significant weight loss and the birds’ migratory orientation being significantly altered.”
The Western Producer contacted Crop Life Canada, which represents the crop protection industry, to respond to the songbird study. A CropLife rep said the organization would comment but that no one was immediately available.