Tracey Baute, Field Crop Entomologist and Paul Kozak, Provincial Apiarist, OMAF and MRA
The issue of what is impacting honey bee health in Ontario is complex and multifaceted. There are still many unknowns and research is underway to try and address some of those factors. While there are many theories being promoted in the public forum about what may be the root cause of the honey bee health issue, there are a number of facts about the bee kills in the spring of 2012 that cannot be ignored.
Growers will need to implement a range of best management practices to reduce the risk of exposure of bees to neonicotinoid contaminated dust during corn and soybean planting season in 2014. A time sensitive first step is the ordering of non-insecticide treated seed where appropriate.
During 2012 and 2013, when a bee kill incident was/is reported in Ontario, the Pest Management Regulatory Agency (PMRA) of Health Canada leads the investigation with support from the Ministry of Environment (MOE) and bee inspectors from the Ontario Ministry of Agriculture and Food (OMAF) and the Ministry of Rural Affairs (MRA). During the visit to the bee yard, samples of dead bees are collected for pesticide residue analysis and other potential aspects of bee health are also investigated, including the health of the colonies and the beekeeper’s pest and disease management practices, to rule out any other potential causes of the bee kill.
Based on the information generated from the investigation of the bee deaths at 240 bee yards the following are some of the conclusions from the PMRA’s investigation into the 2012 reported bee kills:
- The mortalities coincided with corn planting, and information collected from growers confirmed large areas of land near the bee yards were planted with corn, and many growers used negative vacuum planters and talc.
- The symptoms in the bees were consistent with the neonicotinoid poisoning.
- In the spring of 2012 the hives were very strong and the beekeepers indicated that the overwinter success was very good.
- With the exception of the bee yards managed by one beekeeper, there was no indication that disease or pest pressure was abnormally high based on health inspection reports.
- Bee samples were collected from both affected and unaffected hives. Of the 127 samples of dead bees/dozy bees from affected hives, 73% of the samples came back with clothianidin residues on them. This is in stark contrast to results from the unaffected bee samples where only one sample of the 20 analysed (5%) was found to have clothianidin on it.
- Of the 240 Ontario bee yards assessed, in 235 (98% of the yards) the information collected and/or residue analyses conducted led the PMRA to conclude that clothianidin/thiamethoxam, both neonicotinoids used to treat corn seeds, contributed to the honey bee mortalities.
- The unusually warm and dry weather during the spring of 2012 is thought to be a contributing factor to the high bee mortality rates but during the spring of 2013 the PMRA again received a significant number of reports of pollinator mortalities, comparable to the 2012 incident report totals. The investigation into the 2013 mortalities is still underway. To see the PMRA report the “Evaluation of Canadian Bee Mortalities that Coincided with Corn Planting in Spring 2012” go to http://www.hc-sc.gc.ca/cps-spc/pubs/pest/_decisions/bee_corn-mort-abeille_mais/index-eng.php
As stated in the PMRA’s final report of the bee mortalities in 2012, “the information evaluated suggests that planting of corn seeds treated with the nitro guanidine insecticides clothianidin and/or thiamethoxam contributed to the majority of the bee mortalities that occurred in corn growing regions of Ontario in Spring 2012. The likely route of exposure was insecticide contaminated dust generated during the planting of treated corn seed.”
We need to focus our attention on making changes on production practices that we know impact bee health. Growers need to take steps to minimize the drift of contaminated dust at planting so that we reduce the risk of exposure of neonicotinoid seed treatments to bees and other pollinators. Best Management Practices have been developed by OMAF and MRA and information is available to help growers determine if fungicide only seed treatment options are right for their fields. Immediate action needs to be taken when it comes to ordering this seed for 2014. For further information on this effort, go to: http://www.omafra.gov.on.ca/english/crops/pollinators.html
This issue will continue to evolve as more research is finalized but we need to be proactive and take action on the information that is known now.