Bee deaths are getting a lot of attention. New research shows this mystery could be linked to seed treatments
After Ontario recorded 240 bee kills last year, involving 40 different beekeepers, it’s no surprise that the issue of bee deaths has been front and centre in the media or that there is confusion about the various research reports that have been unearthed.
Shrinking numbers of honey bees across Europe and North America has prompted an enormous amount of research into the phenomenon of Colony Collapse Disorder and bee kills like the ones in Ontario. Published studies to date have implicated pesticides, GMO’s, fungi, pathogens, pests, climate change and even radiation emitted by cell phones.
But a number of scientists have conclusively linked the insecticide family neonicotinoids with bee kills.
This is not surprising, as neonicotinoids are toxic to all insects and bees are just one of the non-target insects that are affected by them. What is surprising, however, is that neonicotinoids are generally used as a seed treatment for many crops such as corn, soybeans and canola. They’ve gained popularity partly because of the reduced environmental impact of using this technology.
“One of the main things about the technology of seed treatment, which has made it really take off over the last decade or so, is that much less insecticide product is being used on a per acre basis and exposure to non-target organisms was greatly reduced,” says Pierre Petelle, vice-president, chemistry at CropLife Canada. “It is one of the attractive parts about seed treatments. Producers can put that treatment on the seed, or purchase the seed already treated, and then put that seed under the ground, so in terms of non-target insects the exposure is much less than if you are spraying over the entire field.”
The issue is really about how the bees are being exposed to the insecticide, and the main culprit it seems is the lubricant dust emitted from air seeders. To help make sure that the seed flows smoothly through the air seeder, a lubricant is used — especially for corn and soybeans, but also for crops like canola, which is generally made of talc or graphite.
“What we have identified as a potential original cause of exposure is the vacuum planters which most of the growers are using,” says Tracey Baute, field crop entomologist at the Ontario Ministry of Agriculture and Food and Ministry of Rural Affairs (OMAF and MRA).
“The talc or graphite lubricant is abrasive to the seed and takes off some of the coating, so some of the seed treatment gets into the talc and the insecticide-laden talc or graphite dust is exhausted into the air and makes contact with the vegetation that the honey bees are foraging on.”
This discovery has led to a number of initiatives to try and reduce the potential risk of exposure for bees and other non-target insects. Industry researchers working in association with CropLife Canada are tested a new talc replacement product across North America. “This new type of lubricant shows very promising results and is being tested in a wide area and with a wide range of different planting equipment in collaboration with equipment manufacturers,” says Petelle. “If these trials continue as well as they have been going the idea would be to replace all of the talc and graphite used with this new product as early as next year.”
A set of Best Management Practices (BMP’s) for seed-applied insecticides have been drawn up which closely follow pollinator protection guidelines established by the Pest Management Regulatory Agency last year. These include ways to minimize the risk of insecticide dust exposure during planting, which include making sure that farmers only use the recommended amount of lubricant and are aware of weather conditions, especially wind direction, and hive proximity.
“I think growers sometimes err on the side of caution and probably use more lubricant than they need to and that over abundance is probably not helping, especially on non humid days,” says Baute. “When it’s not humid the seed is less likely to stick in the planter, so if they use exactly what their planter manufacturer recommends it should help reduce the production of contaminated dust.”
The biggest challenge the industry is working to address is communication between growers and bee keepers. “Growers may not even realise that there are bee hives nearby,” says Baute. “And they clearly didn’t have the knowledge that bees can forage as far as they do.”
The industry has been very proactive in trying to encourage more dialogue on the issue, says Petelle. CropLife Canada has established an informal round table which brings together its member companies, the beekeeping community, grower groups, government and regulators and equipment manufacturers to share information and try to find solutions to bee health issues.
Research from Purdue University is also suggesting that there could be insecticide residue in the soil, which could be finding its way into water sources like puddles or ponds and providing another route for exposure. Other studies suggest that residues could also be present in nectar and pollens at either lethal or sub-lethal doses.
“This is where it gets really tricky,” says Baute, who is involved in a year-long study in collaboration with the University of Guelph and OMAF and MRA into these kinds of potential exposure routes. “There could potentially be residues in the nectar and pollen from the vegetation along the perimeter of the fields but are those residues high enough to have an impact on these bees? There are still a lot of gaps in the knowledge.”
Petelle cites data from independent studies that are finding the amount of insecticide residue present in pollen and nectar from canola crops treated with seed treatments is infinitesimally low and is not a significant source of exposure for bees. According to data from Statistics Canada, in Alberta, where more than 2.5 million hectares of canola were planted last year (almost all of which was treated with neonicotinoids) bee numbers are increasing in parallel with seeded area.
“Canola is a highly attractive crop to bees and if there were issues around sublethal effects, they would appear in this crop,” says Petelle. “So we always point to that as a clear example that if the pollen and nectar were truly a significant source of exposure we would be seeing problems in canola.”
Petelle believes that many different factors affect hive health, not least of which are old enemies such as the Varroa mite, a parasite that attaches itself to bees. Some companies are investing heavily in bee health products and technology, he adds.
Bayer Crop Science, for example, has a dedicated bee health research facility in Germany and is opening a similar one in Raleigh, North Carolina, with full scale bee hives and testing facilities for new products to try and control mites and other hive health issues.
It does appear that issues with bee kills linked to the use of neonicotinoid seed treatments are more prevalent in Eastern Canada where more corn and soybeans are grown. Some Eastern farmers have been trying out European designed deflector kits, which they use to modify certain types of air seeders so exhausted air is pointed in a downward direction.
North American equipment manufacturers have concerns about the kits. “The use of deflectors on equipment disrupts the airflow through the planter and could create performance issues,” says Nick Tindall, director of government affairs for the Association of Equipment Manufacturers. “We are also concerned that changing the direction of the exhaust downward may not be the best course of action to protect pollinator health.”
Tindall says equipment manufacturers are taking pollinator health seriously and have taken steps to mitigate any potential role that their products play in fugitive dust from treated seed. Besides being involved in the testing of the talc replacement product they are also working to create a new ISO international standard for equipment manufacturers to follow to better control fugitive dust.
Baute would like a return to emphasis on Integrated Pest Management as a way to mitigate the risk of accidental insecticide exposure to bees and other non-target insects. “With Integrated Pest Management you assess if you have a pest problem before using a seed treatment,” she says. “I think that’s where we want to move towards, so we are only using a seed treatment when we really need to.”
Honey bees are extremely valuable as crop pollinators for crops. Small expenditures in strategies to preserve them seem like a pretty good investment. †