The southern Ontario spring of 2012 was an early one, and corn growers got busy as soon as they could get their planters out into the fields.
Beekeepers got their troops mobilized early too, but high hopes for a good season quickly evaporated as the body count started piling up around the hives. It turned out the culprit may have been the insecticide from the corn seed.
“It’s seeded with a neonicotinoid — either thiamethoxam or clothianidin,” explains Dr. Maria Trainer with the industry group Croplife Canada. “When the Pesticide Management Review Agency and the Ontario Ministry of Agriculture and Food investigated, they confirmed that those residues were found in about 70 per cent of the dead bee samples and their conclusion was the bees were exposed to dust that was released during the planting of the seed through the planter.”
There’s been a lot written in the popular press about neonicotinoid pesticides along with their potential effect on honeybees, and the news sounds grim. The Europeans suspended the use of neonicotinoids and there’s a lot of pressure from various environmental lobbies to do the same thing here. What doesn’t show up in the popular press is how long farmers have been using neonicotinoids without major bee kills.
Neonicotinoids were first used in Canada back in the late 1990s with the registration of imidacloprid, and farmers across the country have used them on a wide variety of crops including soybean, corn and canola. They work by blocking an enzyme that regulates the transmission of impulses over the bridge between two nerve cells. With impulses jumping the gap completely unchecked, the insect goes into convulsions and burns out.
Neonicotinoid chemistry is tuned so that insects are quite sensitive to it but mammals, such as wildlife, livestock and us are, much less so. Although it can be applied as a foliar spray, it’s often put on the seed as a coating, which has a number of advantages.
“They’re safer for the user because they’re applied off-site at a controlled facility, so you’re not having to get your arms into the planting equipment and get exposed to those chemistries,” Trainer says. “They’re better for the environment because the amount of insecticide used in a seed treatment is significantly less, about one per cent of what you would use in a broadcast application.”
Seed treatment also helps to zero in on target species, such as flea beetles in canola or rootworm in corn, making the application much safer when done according to the label instructions. The spring bee kill in 2012 wasn’t a typical event and shouldn’t have happened.
“In 2012 we had an exceptionally warm spring,” Trainer says. “Flowering weeds were up early so the bees were out foraging in areas where they wouldn’t normally be foraging, adjacent to fields during planting.”
The seed is coated with a number of different treatments such as fungicides, insecticides and a lubricant to make planting easier on both seed and machine. It’s the lubricant, or fluency agent, that actually caused the trouble in an air seeder. The combination of talcum and graphite doesn’t stick to the seed as well as it might, so when planting corn, there may be a cloud of insecticidal dust that drifts off the seeder. It was this dust that seems to have produced the bee body count.
There’s no doubt that enough exposure to an insecticide is going to kill bees, but to maintain yields we’re stuck using chemistry. Farmers understand that there’s no trade-off here, we need bees as much as we need insecticide, not only for the honey they produce but also for the pollination they provide. It’s an old relationship that a full 70 per cent of the world’s top 100 food and fibre crops still remember from their wild past. One of every three mouthfuls any of us eat comes courtesy of an insect pollinating a plant.
The real question is: can we use the chemistry better? Can we develop products and management practices to keep the bees away from the seed treatments so we can have both? The first answer revolves around new coatings that keep the insecticide on the seed where it’s needed rather than in the air where it’s hazardous.
From the Grainews website: New seed flow lubricant to be only one allowed on corn, soy
The company that marketed the original talcum/graphite fluency agents, Bayer CropScience, is working on the next generation of seed coatings. Bayer began using a polyethylene wax treatment and has run field trials in both Canada and the United States. Feedback from farmers has been very good, and early results show the lubricant performs at equal or even better levels than the older mix, while significantly decreasing the amount of dust generated.
The PMRA is making the new fluency mixture mandatory for the 2014 growing season and this is the first of their four new requirements. Another is to open the channels between beekeepers and farmers and get them talking to each other. Beekeepers need to know when farmers are planting or engaging in any kind of action that may put bees at risk. Farmers need to know where the hives are and what kind of range foraging bees have. Both need to be aware of what the weather conditions are because this often dictates what both farmers and beekeepers do.
The third is labelling the products with updated seed tags so that farmers know what they’re buying and have a good set of instructions. For the longer term, CropLife Canada and the PMRA have developed a set of best management practices for the use of treated seed. The risk is greatly diminished if bees and insecticides don’t mix.
If farmers can simply minimize the amount of dust generated during seeding that should go a long way to minimize bee mortality and still keep an effective insecticide on the roster.
In the short term, be aware of where hives are located and consider the weather conditions during seeding. Make sure planting equipment is in good working order and that treated seed is handled properly to minimize the amount of dust. Excess dust within the bags should stay there instead of being shaken into seeding equipment and the bags should be properly disposed of.
In the longer term the seed companies will develop better coatings that increase the efficacy of their product while reducing the amount of dust generated. Equipment manufacturers are working on seeders. One of the problems there is the air exhaust that vents too high. Reworking the exhaust systems so that they vent close to the ground is a solution for the long term, and retrofits that redirect the air exhaust downward is in the works for older machinery.
“PMRA has investigated and according to the interim report they’ve released their conclusion that direct exposure due to dust during planting was an issue and this needs to be addressed ahead of next year’s growing season,” Trainer says. “In response to what happened, both the PMRA and EPA have put the three main neonicotinoids under re-evaluation and have released a pollinator risk assessment framework that is now guiding internal pollinator risk assessment.”
The spring of 2012 may have had unusual consequences because of that early warming but it was typical of many mishaps. A small change in circumstances can bring about a disaster of sorts but there is a silver lining. We know more about the behaviour of those seed coatings and we’ve been able to improve on them. We know more about the equipment we use and how we can make it better. We know enough to refine the procedures and we can make the products work better.
“We are very supportive of that approach and for Canadian agriculture we think it’s very important that the transparency and predictability of the regulatory system remain intact,” Trainer says. “We also support ongoing research into the various factors that affect pollinator health of which insecticides one of the factors.