Beekeeper Survey - 2011 Winter Loss Report for Apiculture in Ontario

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During the Spring/Summer of 2011, the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) sent a survey to Ontario commercial beekeepers to estimate honey bee colony mortality over the winter of 2010/11. Eighty-six out of the 218 (39.4 percent) registered commercial beekeepers contacted, responded to the survey.

This report is based solely on the responses provided by the beekeepers who completed the survey. It should be noted that the data collected was not independently verified by OMAFRA and that some data was difficult to analyze due to a low number of responses to particular questions. For example, a greater response to analysis of treatment methods may have yielded different results. This highlights the need for a higher number of commercial beekeepers to respond to future surveys as well as the need for a reminder to respondents to complete all questions in the survey.

The survey was anonymous. It followed the same template as the National Apiculture Survey conducted through the Canadian Association of Professional Apiculturists. Survey results will be combined with the National Apiculture Survey to provide estimated winter morality information across Canada. In addition to mortality levels, the OMAFRA survey tracked some colony management and management practices for pests and diseases in honey bees.

Bee Mortality

The survey responses estimated the winter 2010/11 level of honey bee colony mortality among Ontario commercial beekeepers at 43 percent (mean) with a median of 41 percent. This is a substantially higher estimate than in any previous year. According to the literature, a normal level of winter mortality is typically considered to range from 5 to 15 percent (Furgala and McCutcheon, 1992).

Many of the beekeeping operations that responded to the survey reported their losses well above the mean, up to 60 percent in the 75th percentile of the respondents. At the same time, some beekeepers reported much lower wintering losses in the 5th percentile, at 10 percent mortality. Although the range of wintering losses reflects a wide variation in mortality among different operations (2 to 95 percent winter mortality), both the median and mean are indicative of high loss levels.

The level of winter mortality was separated by geographic region for comparison. Estimated mortality rates were as follows (counties are in brackets):

  • Near Northern Ontario (Bruce, Dufferin, Grey, Glengarry, Frontenac, Kawartha Lakes, Lanark, Leeds, Lennox and Addington, North Wellington, Ottawa, Carleton, Simcoe, Stormont, Victoria) - 39 per cent
  • Northern Ontario (Nipissing, Renfrew, Sudbury) - 41 per cent
  • South Central Ontario (Durham, Hamilton, Hastings, Huron, Northumberland, Oxford, Peel, Perth, Peterborough, Prince Edward, Waterloo, Wellington) - 47 per cent
  • Southern Ontario (Elgin, Haldimand, Kent, Lambton, Middlesex, Niagara, Norfolk) - 44 per cent

Statistically, there was no significant difference in mortality rates between the different regions.

In previous years, survey respondents estimated levels of winter mortality among honey bee colonies in Ontario at:

  • 20 percent in 2003
  • 18 percent in 2004
  • 19 percent in 2005
  • 14 percent in 2006
  • 35 percent in 2007
  • 32 percent in 2008
  • 31 percent in 2009
  • 20 percent in 2010

In 2007, the high level of estimated mortality was identified as a major concern for the industry. This was followed by two more consecutive years (2008, 2009) of high winter mortality for an estimated overall average of 33 percent over the three years. This is outlined in Figure 1.

Graph depicting estimated mortality of bees in Ontario.

Figure 1: Estimated mortality of honey bees in Ontario. The light coloured horizontal bar represents the normal level of mortality derived from a literature review.

Link to text describing figure 1

Management Practices and Treatments

Although there are many potential reasons for a colony not surviving the winter (e.g. varroa infestation, starvation, small cluster size, etc.) and there are many theories for the increased mortality in honey bee colonies (e.g. ineffective varroa control, new pathogens, pesticides, combination of multiple factors, etc.), the survey focused, to a large degree, on management techniques and treatments for varroa used by beekeepers. This emphasis was based on a study from the University of Guelph (Guzman et al., 2010) which identified varroa as being the primary factor in colony mortality in Ontario.

Of the respondents, 50 (58.5 percent) reported monitoring for varroa mites. Among the monitoring methods, mite or alcohol wash was the most popular (40 percent), followed by the sticky board (25 percent).

All survey respondents reported treating for varroa mites in the fall of 2010. The majority (82 percent) of beekeepers treated between late August and mid-September. Only 12 percent of all respondents treated in late September or later. As late fall varroa treatment has typically been associated with high mortality, correlations were done between treatment time and mortality. Statistical analysis of survey data did not reveal any significant relationship between treatment time and mortality. Other factors may have impacted this correlation, therefore caution should be applied in drawing any conclusions. Beekeepers should still treat for varroa in a timely manner.

Beekeepers continue to use a variety of treatment methods for varroa. Among survey respondents, the most popular treatment was Apivar® (37 percent of respondents), followed by formic acid (19.5 percent) and then by a combination of various treatments, including oxalic acid. CheckMite+ (2.4 percent) and Apistan® (1.2 percent) are still being used, although by fewer beekeepers.

A statistical analysis (Kruskal - Wallis test) of the four major treatments (Apivar®, Apivar®/Formic Acid, Formic Acid, Formic Acid/Oxalic Acid) revealed no significant difference (p=0.30) between the levels of winter mortality.

Forty-five percent of the survey respondents treated for nosema in the fall. There was no statistical difference in mortality levels between those beekeepers who treated and those who did not.

Beekeepers subjectively attributed mortality to ineffective varroa control, nosema, poor queens, weak colonies, and weather.

Queen Management and Colony Replacement

According to survey respondents, roughly one in three queens (32 percent) were replaced with new queens amongst operations, with the 75th percentile at 50 percent. The level of queen replacement attributed to queen problems averaged 10 percent. For the most part, replacement queens used by beekeepers were sourced from within the province. Australia was the largest source of out-of-province queens. Queen bee origin is outlined in Figure 2.

This image indicates the origin of queens in Ontario by type.

Figure 2: Origin of honey bee queens in Ontario.

With respect to replacement colonies, beekeepers reported roughly one in three colonies (36 percent) were new. The replacement level was not significantly different across the different regions of the province.

Link to text describing figure 2

Pollination Services

On average, 18 percent of the colonies represented in the survey were used for pollination services in 2010. Some of these operations used 80 to 100 percent of their colonies for pollination services. Southern Ontario had the highest proportion (34 percent) of colonies used for this service.

General Comments

The reasons for the overall levels of mortality province wide are a matter of speculation on the part of the author. However, the following are some potential factors:

  • Based on research from the University of Guelph (Guzman et al., 2010) and reports and field observation from other provinces (Currie et al., 2010), varroa is still the main factor in colony mortality. The overall virulence of Nosema ceranae in honey bees is somewhat unclear and there are many other pathogens such as viruses that have a further impact on honey bees.
  • Weather patterns may have had some impact on the survival of colonies. Last year, in most parts of the province, there was an early spring (April 2010), up to three weeks earlier than normal in most regions. This would have resulted in much earlier brood production in honey bee colonies and varroa reproduction.
  • Without effective varroa control in the spring of 2010, it is possible that many colonies may have been going into the fall with much higher varroa levels than a typical year. This is only speculation as no data was collected to demonstrate varroa levels increasing earlier than normal.
  • In many regions (south-western Ontario), the winter (November 2010 to March 2011) was also much colder and longer than usual, making weak and underfed colonies particularly vulnerable. Furthermore, this spring (April 2011 to June 2011) arrived very late with uncharacteristically cool and damp conditions. This resulted in a delayed population build-up in many colonies. Many beekeepers had to feed colonies just to maintain their population. Anecdotal reports from some operations revealed that the poor spring conditions resulted in substantial increases in winter losses well into mid-spring.

Colony Collapse Disorder, which has been identified in the USA, has not been identified in Canada. To be clear, this disorder has been associated with a distinct set of conditions that has not been presently validated in Canada (vanEngelsdorp et al., 2008; Currie at al., 2010).

Based on survey results, it appears that in 2010-2011, Ontario commercial beekeepers experienced increased levels of mortality in honey bee colonies beyond historical levels.

Recommendations for Future Surveys

The survey provided a snapshot of the health of the industry. It would be useful for future surveys to track pest and parasite levels to also have an idea of infestation intensity across the province. A greater level of beekeeper participation and completion of all survey questions would greatly enhance the quality of the data extracted from future surveys.

Paul Kozak
Provincial Apiarist
Ontario Ministry of Agriculture, Food and Rural Affairs
Foods of Plant Origin
Food Inspection Branch
1 Stone Road West, 5th Floor NW
Guelph ON N1G 4Y2
Tel: 519 826-3595 or 1-888-466-2372 Ext. 63595
Fax: 519 826-4375


Currie R., Guzman E. and Pernal, S. 2010. Honey bee colony losses in Canada. Journal of Apicultural Research. 49 (1): 104-106.

Furgala B., and McCutcheon, D.M. 1992. Wintering productive colonies. In Graham J M (Ed). The hive and the honey bee (revised edition). Dadant and Sons; Hamilton, IL, USA pp. 829-868.

Guzman-Novoa E., Eccles L., Calvete Y., McGowan J., Kelly P. and Correa-Benitez A. 2010. Varroa destructor is the main culprit for death and reduced populations of overwintered honey bees in Ontario, Canada. Apidologie. 4 (4) 443-451.

VanEngelsdorp D., Hayes, J JR., Underwood R.M. and Pettis J. 2008. A survey of honey bee colony losses in the U.S., fall 2007 to spring 2008. PLoS ONE3(12):e4071. DOI: 10.1371/journal.pone.0004071

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