As insects go, bees undoubtedly lead the polls of popular opinion. While most of us will continue to give them a wide berth for fear of being stung, we as a society are increasingly aware of the unparalleled contribution these humble, hardworking creatures make to our way of life. More specifically, we have a growing appreciation of their crucial role as pollinators for nuts, fruits and vegetables that make our diet healthier and more diverse than it would otherwise be.
This prominent public profile also means we pay more attention to any problems bees may be suffering, especially if we happen to be the cause. That is how the technical term neonicotinoids has managed to creep into so many news stories in the past few years. This widely used class of insecticides has been put forward as a primary culprit in the die-off of bee populations, especially those in commercially maintained hives. Scientific evidence has reinforced claims that sufficient amounts of this agent can be harmful and lethal to bees, so much so that in 2013 regulators in the European Union voted to ban the use of these compounds in agriculture on that continent.
Experts point to the neuro-active insecticide neonicotinoids, a potent stimulant of acetylcholine receptors found in all neurons of mammals, as the reason for the success of 20 million acres of prairie canola, a crop that is also a source of nectar and pollen for bees.
That move redoubled the steady chorus of calls for a similar ban on this side of the Atlantic in jurisdictions such as Ontario, where beekeepers have been particularly outspoken about the link between these agents and declining bee populations. The provincial government is close to imposing just such a restriction, but Bayer CropScience — the German multinational that is the leading producer of neonicotinoids — has been working on methods of delivering the insecticide so as to minimize its impact on bees. In fact, the science is far from settled, raising questions about how much injury neonicotinoids may be inflicting on domesticated bees, as well as whether this is even among the greatest threats these insects face.
For starters, the application of neonicotinoids rarely involves the spraying or dusting technique that is often associated with pesticides. Instead these chemicals are coated onto the surface of crop seeds. From there, they are quickly absorbed and spread through the plant’s growing tissue, providing protection during the vulnerable initial days and weeks of its life. These compounds target a broad range of insects that can significantly compromise the yields of major crops such as corn, soybeans, cereals, canola, cotton, potatoes and rice.
As their name implies, neonicotinoids assume the same mechanism of action associated with the highly addictive alkaloid that has been favoured by billions of smokers since the European discovery of the Americas. Given the disdain that smoking has earned in so many social quarters, any agent incorporating the function and name of nicotine is bound to be tarred with the same brush. Nevertheless, neonicotinoids have succeeded for the same reason that nicotine use became so widespread: this stimulant is a potent binder of acetylcholine receptors found in all neurons of mammals. Insects have these receptors too, but located exclusively in their central nervous systems. This leaves them vulnerable to overstimulation by nicotine, which deals a toxic blow to the organism by paralyzing and killing these cells.
The first neonicotinoids based on this principle were developed by Bayer CropScience, an offshoot of the 150-year-old chemical firm that made aspirin a household commodity. Introduced in the 1990s, neonicotinoids have since become one of the most widely used class of insecticides in the world. Part of their appeal is a matter of cost effectiveness, as they require far lower amounts of active product than other types of insecticide. “You’re putting just the right amount of chemical on the seed,” says Murray Belyk, Bayer CropScience Canada’s manager of scientific affairs. “Only a small part of the environment is actually exposed to the treated seed. It’s a very sophisticated application technique, rather than taking your sprayer out and treating the entire field with post-emergent spray, subject to the winds and drift into non-target areas.”
In addition to neonicotinoids, which compromise bees’ immune systems, Varroa destructor mites are a significant factor in bee die-offs, according to Simon Fraser University biologist and bee expert Mark Winston.
It might appear easy to cast the company as having a vested interest only in selling its neonicotinoid-coated seeds, regardless of how they might affect bees. However, Belyk is quick to point out that this product is responsible for the success of some 20 million acres of canola planted across the Canadian prairies — a crop that is also an important source of nectar and pollen for bees. “We have a very important relationship with pollinators — short and long term — and we depend on beekeepers to fulfill this demand for canola seed,” Belyk says.
Beekeepers on the prairies have not accused neonicotinoids of being a major cause of bee mortality. Instead, their primary worry is the mites that invade the hive and feed on larvae and adult bees. Belyk recalls raising bees while growing up on a farm in Saskatchewan in the 1970s, when hives were simply destroyed at the end of each season and new ones started the following spring using bees shipped from hives in the southern United States. That practice came to an end in the 1980s, when the invasion of mites from Europe forced Canadian authorities to close the American border to the trade. Beekeepers suddenly had to find a way to keep their hives going throughout the harsh Canadian winter, which often meant coming to terms with a significant die-off from year to year.
Beekeepers in Ontario have had to come to grips with these same challenges — Varroa destructor mites and overwintering — but they have also made neonicotinoids a cause célèbre. In an official position statement calling for a moratorium on the use of these products, the Ontario Beekeepers’ Association (OBA) cited the indiscriminate and incorrect use of neonicotinoids-treated corn, soy and winter wheat as the major cause of bee population declines in the province. Formal studies by the federal government’s Pest Management Regulatory Agency (PMRA) in 2012 and 2013 confirmed that bees in close proximity to these crops were suffering from exposure to neonicotinoids significant enough to kill them. This observation prompted the Ontario government in July 2014 to announce a future requirement for growers to apply for permits to use neonicotinoids-treated seeds.
Belyk suggests that the PMRA considered bee mortality only in the context of neonicotinoids, rather than other causes such as disease infections. He concedes, however, that bees near planting areas can receive high doses of insecticide because of the mechanics of the process. The machinery that ensures uninterrupted pinpoint accuracy for placing corn seeds in the ground relies on a dry lubricant such as talc or graphite to ensure smooth travel of the seed down a delivery chute. Unfortunately, the exhaust fans running this apparatus can stir up dust that blows throughout the immediate area, potentially carrying neonicotinoids-tainted lubricant with it.
In response, Bayer CropScience developed what it dubbed a fluency agent, a polyethylene wax lubricant that reduces the volume of such dust by as much as two-thirds. The effect of this additive, which was launched at the beginning of this year, is still being studied. Obviously the company wants to continue selling neonicotinoids in Ontario, but Belyk warns that an outright ban on this product, which would be the first in North America, could force farmers there to revert to less attractive methods. “Just because you take a product away doesn’t mean the pests go away,” he says. The legally available alternatives would include such products as organophosphate, carbamate and pyrethroid pesticides, which must be used in larger quantities than neonicotinoids and can accumulate in the environment as persistent organic pollutants. The OBA, for its part, insists that the need for these products has been overstated and crop yield losses following a neonicotinoids ban would be no more than a few percent.
Regardless of the regulatory and environmental outcome, says Simon Fraser University biologist Mark Winston, neonicotinoids represent just one facet of the difficulties facing bee populations around the world. His career has been dedicated to studying the intricate dynamics of these insects, which he has summarized in a recently published book, Bee Time: Lessons From the Hive. According to Winston, bees’ intimate exposure to rising levels of chemicals like neonicotinoids makes them a bellwether for changes that could affect all of us. These and other pesticides may not necessarily be killing the insects directly, but they are among a number of factors compromising their immune system. Wild bees would normally be able to throw off infections caused by Varroa destructor mites, but domesticated varieties are less able to do so. Some of this weakness is owing to environmental contaminants, but he also blames a stressful lifestyle, one in which bees are regularly moved from place to place and forced to forage on specialized mono crops. “It’s kind of crazy way to make a living,” says Winston, pointing to examples such as the extraordinary proportion of American bee colonies that are used just to sustain almond production in California.
The best way of addressing the plight of domesticated hives, Winston suggests, is balancing their needs with those of wild bees, which tend to be superior pollinators. He has overseen research that demonstrates how farmers can actually plant a smaller area of their farms and enjoy a higher overall yield, simply by setting aside a diverse, undisturbed area for wild bees to thrive. “What is being found all over the world is that when you provide the right habitat for bees, they come back,” he says. “We need to shift the way we think about crop pollination and not think about honeybees as the primary pollinator but think of wild bees as the primary pollinator with honeybees as the supplement when needed.”
That approach might not sit well with beekeepers in Ontario, whose numbers have swelled by 40 percent since 2008, according to a Statistics Canada report. In fact, if the dilemma surrounding neonicotinoids teaches us anything, it is that there are no constant winners or losers when it comes to bees, where the solution to one party’s problem simply becomes someone else’s problem.
Geoff Wilson, the provincial specialist in apiculture for the Saskatchewan government, has encountered this paradox regularly. Most recently it was when the province spearheaded the Canadian adoption of an American program called Driftwatch, which sets up an on-line system where pesticide producers, farmers and beekeepers can keep tabs on one another’s operations, so that no one should unwittingly apply a product in a field where bees are currently located. The program has worked well so far, but Wilson maintains that it can only minimize accidents, as opposed to solving fundamental problems like having bees pollinate fields that have already been treated for pests. Such conflicts appear to be woven into the intricate fabric of the lives led by these insects. “That’s bees,” Wilson concludes.