A raft of new research published over the summer is posing ever more serious questions about whether neonicotinoids, the most common insecticides in the world, are affecting birds and bees more widely than previously thought.
The research is looking into more subtle, long-term effects from the insecticides – rather than instant direct kills – that may still harm bird and bee populations.
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Through a four-week study on bumblebees, Nigel Raine, an expert in pollinator conservation at the University of Guelph, found that the neonicotinoids, which are neurotoxins, affect bumblebees’ ability to find and collect food.
“When the neonicotinoid-treated bees go out of the colony for the first time to look for flowers, something about their exposure to that pesticide means that they’re less able to collect as much pollen as the bees that are untreated,” he told the CBC Radio program Quirks & Quarks.
“And that impact only gets worse over time, because the untreated bees improve their performance and their ability.”
In turn, that leads to smaller colonies, which in turn means that fewer queens are produced, a phenomenon that decreases the number of new bumblebee colonies.
Pollinators, including honeybees and wild pollinators, are in decline around the world, Dr. Raine said, adding that a host of factors is thought to be responsible.
Pierre Petelle, vice-president of chemistry at CropLife Canada, told Quirks & Quarks that the industry’s studies suggest that neonicotinoids are not one of them.
The insecticides — known as “neonics” for short — are responsible for some bee deaths in Ontario and Quebec in 2012, after dust kicked up from their application reached some colonies.
Petelle said both manufacturers and farmers are working to make changes to the way the pesticide is applied and are resolving those problems.
The European Community has banned some neonics for two years and the Ontario government is considering a plan to reduce or eliminate some of them.
Beekeepers in Ontario have launched a $400-million lawsuit against neonic manufacturers.
Birds' food may be at risk from neonics
When it comes to birds, the question is whether neonics are such an effective insecticide that they are killing off the aquatic bugs that birds need to eat, leaving too little food for them.
Christy Morrissey, an ecotoxicologist at the University of Saskatchewan in Saskatoon, found last year that 90 per cent of prairie potholes were laced with small amounts of neonics in the spring before farmers planted their fields. That means the chemicals stay in the soil and then wash into the water through rain or snow.
"Insecticides or pesticides in general are not supposed to be on the market if they persist [in the environment]," Morrissey told Quirks & Quarks from her research site in Saskatchewan.
“We do not want chemicals that are designed to kill lasting in the environment for weeks, months or years. …You want pesticides to be applied, do their job, kill the pest and then be gone."
Now, Dr. Morrissey is in the midst of a study in the field studying exactly how different levels of neonics affect aquatic insects in prairie potholes, in tandem with a long-term study examining the health of tree swallows nearby.
It’s a bid to examine whether neonics are affecting the bugs and, consequently, the birds that rely on them. Her early results show that birds living near treated fields are slightly delayed in laying their eggs, and the chicks are not as healthy.
'We do not want chemicals that are designed to kill lasting in the environment for weeks, months or years.' - Christy Morrissey, an ecotoxicologist at the University of Saskatchewan
A Dutch study by Caspar Hallmann at the Institute for Water and Wetland Research at Radboud University in the Netherlands, and others published this summer found larger annual declines in insect-eating birds in areas with higher surface-water concentrations of the most popular type of neonic, imidacloprid.
It concluded that the impact of the chemical is “reminiscent of the effects of persistent insecticides in the past.”
CropLife Canada's Petelle said the concentrations of neonics Dr. Morrissey is finding in the field are too low to affect aquatic insects.
He said neonics are the safest chemical solution that has been introduced in a long time, one reason that agriculture has never been more sustainable than today.
“And so the studies that have been conducted on these products in field conditions show that at those concentrations, there is no risk for aquatic insects or other wildlife,” he said.
Dr. Morrissey told Quirks & Quarks, however, that the industry is relying on studies conducted on the water flea, Daphnia magna, an aquatic crustacean.
While it is the industry standard for testing, it happens to be almost uniquely insensitive to neonics. Compared to other insects tested, it is an average of 1,000 times less sensitive, and compared to the aquatic insects birds like to eat, it is between 10,000 and 100,000 times less sensitive, she said.
Neonics, which are derived from nicotine, are the newest class of insecticides and they are used in a new way: as a coating for crop seeds rather than mainly as a spray on growing crops.
In Canada, all canola and corn seeds planted are coated, as well as half of soybeans and some seeds of other crops. They are systemic pesticides, which means they infuse every cell of the plant as it grows, right from the roots to the leaves, seeds, nectar and pollen.
And they are used as a prophylactic, whether there is a pest infestation or not.
An analysis of 800 studies released this summer, called the Task Force on Systemic Pesticides, concluded that the chemicals, including neonics, are having widespread effects on ecosystems around the world beyond their intended function of killing crop pests.
The scientists who conducted the review study said governments should plan for a global phase-out or at least a plan for farmers to use them only when their crops are actually threatened by insects.