Review of Bee Health

16×9 Story Does Not Provide a Clear Picture on the Cause of Bee Health Decline

October 22, 2013

On Saturday October 19, 2013, the Canadian news program, 16×9, featured a segment titled, Flight of the Bees.  The focus of the story was on bee health decline.  Focusing on the interviews of two individuals, beekeeper Jim Coneybeare and researcher Christian Krupke, the story attributes the decline of bee health to neonicotinoids.   As outlined below, neonicotinoids’ role in regards to declining bee health is misplaced and unsupported by the science.

The Science Shows Varroa Mites are the Cause of Bee Health Decline

In reporting on declining bee populations, the 16×9 segment fails to report on the leading cause—the Varroa mite.  The U.S. Department of Agriculture has identified “the parasitic mite Varroa destructor remains the single most detrimental pest of honey bees and can magnify the role of viruses in bee health.”[1]  The U.S. Department of Agriculture summarized its recent report  by stating:

The parasitic Varroa mite is recognized as the major factor underlying colony loss in the U.S. and other countries. There is widespread resistance to the chemicals beekeepers use to control mites within the hive. New virus species have been found in bees in the U.S. and several of these have been associated with CCD. The Varroa mite is the primary factor known to increase levels of some bee viruses.[2]

Similarly, research supports the USDA’s finding.  A recent study unequivocally states that the Varroa destructor “has resulted in the death of  millions of honey bee (Apis mellifera) colonies.”[3]  The study concluded, “the spread of Varroa in Hawaii has caused [deformed wing virus], originally an insect virus of low prevalence, to emerge. This association may be responsible for the death of millions of colonies worldwide wherever Varroa and [deformed wing virus] co-occur.”

A key conclusion of the USDA report is that “Consensus is building that a complex set of stressors and pathogens is associated with CCD, and researchers are increasingly using multi-factorial approaches to studying causes of colony losses.”[4]

Despite the increasing consensus that bee health decline is caused by multiple factors, with varroa being a leading cause, the 16×9 report suggests neonicotinoids are to blame.  As the following section discusses, the scientific data does not support 16×9’s report.

The Critique of the Scott-Dupree Study Is Premature and Without Scientific Support

The research conducted by Dr. Cynthia Scott-Dupree is a centerpiece of the 16×9 program.  Dr. Krupke and Dave Goulson offered criticism of Dr. Scott-Dupree’s study.  Specifically, both Dr. Krupke and Mr. Goulson argued that the study is flawed, because the hives are not “clean.”  This argument fails.  While “clean colonies” are best to avoid “confounded data,” clean hives fail to represent real-world colonies and real world conditions.  The bees used were “choice colonies” and of “equal strength,” and stored on a military site after exposure to neonicotinoids.  All of the colonies used in the Scott-Dupree study were screened for the presence of agricultural pesticides and all of the colonies used in the study had no detectable residues of any neonicotinoids

The U.S. Environmental Protection Agency (EPA) and Canadian Pest Management Regulatory Agency (PMRA) oversaw and approved the field study protocols and an independent quality assurance team supervised data collection and analysis.  As stated by Dr. Scott-Dupree the shortcomings of lab studies are much greater than field studies, “The importance of these field studies is substantial because a lot of the critical data indicating that neonics are killing the bees is based on laboratory studies,” she said.  Dr. Scott-Dupree continued, “The doses the bees are exposed to (in lab studies) are far above what a realistic field dose exposure would be.”  Importantly there have not been field studies conducted that demonstrate neonicotinoids are harming bees.

Notably, the Scott-Dupree study found that for the bees exposed to neonicotinoids there was no reduction in honey yield, which is an indication of overall colony health.  Similarly, the study found impacts on bee death or weight gain for the bees exposed to neonicotinoids.

The Issue Is Bee Health and not the Economic Health of the North American Beekeeper

In the 16×9 segment, Dr. Krupke states, “We won’t have beekeepers, and that is what in turn will lead to a shortage of bees.”  It is very true that beekeepers have experienced economic pressures related to the profitability of beekeeping.  In particular, the varroa mite, declining forage, Nosema Ceeranae, and increases on the demand of pollination services has led stress on colonies.  These stressors have caused deaths for colonies, however, the overall colony numbers are actually increasing in throughout the world despite  the introduction of neonicotinoids.  See the charts below produced by the Australian Government.  In fact, as shown below, the declines in colony numbers in the United States are more a result of globalization and cheaper honey imports from South America and Asia.

Since 1961 the reported global stock of commercial managed honey bee hives has increased by approximately 45 per cent (Figure 1). The number of bee hives in a particular country depends on a range of social and economic factors affecting the bee keeping industry in that country; Varroa is only one of these factors (vanEngelsdorp and Meixner, 2010).

Figure 1. The number of managed honey bee hives in the world from 1961-2008 (FAO Stat, 2011).

Varroa had no perceptible effect on the number of hives reported in Europe (Figure 2). The number of honey bee hives in Europe declined sharply in the early 1990s, coinciding with the end of communism, and the end of state support for beekeepers, in the previously communist bloc countries of Eastern Europe (Moritz et al., 2010). The number of hives reported Western European countries remained unchanged over the same period of time.

Figure 2. The number of managed hives in the whole of Europe, former Warsaw Pact countries and former EU 15 member countries from 1961-2008 (FAO Stat, 2011).

 

Rising incomes in rural areas, a declining rural workforce and the need to treat for Varroa has led hobby beekeeping to become less popular in some European countries (Potts et al., 2010).

In the United States the number of managed hives has declined steadily since the late 1940s, around 40 years before Varroa established there.[5] This decline reflects declining terms of trade for United States beekeepers as the result of competition with lower-cost honey producing countries in South America. In contrast, due to their competitive advantage, the number of hives in South America has grown steadily since the mid-1970s, despite Varroa already being established there (Figure 3). However, the J strain of V. destructor in South America is less damaging than the K strain of V. destructor in the United States.

Figure 3. The number of managed honey bee hives in the Unites States and South American countries from 1961-2008 (FAO Stat, 2011).

 

While it is clear that beekeepers in the United States and Canada face extremely difficult market conditions for beekeeping, the story by 16×9 suggests the struggles of beekeepers is directly attributable to neonicotinoids.  Instead, as noted  by Dr. Krupke, it is the decline of beekeepers that are affecting the number of managed bee hives.

As the above referenced researched by the Australian government recognizes, the number of managed bee hives has increased globally since neoncotinoids have been implemented.   Reduction in managed hives in North America is a result of Varroa mite and increased competition from beekeepers in South America and Asia.

Conclusion

The story by 16×9 inappropriately focused on neonicotinoids as the cause of declining bee health.  By centering the story on critiquing Dr. Scott-Dupree’s study which has not yet been released, the story failed to address the building consensus that bee health decline is caused by multiple factors, with the primary factor being the Varroa mite.  While more research on neonicotinoids is advisable (consistent with Health Canada’s request), the failure to address the problem of Varroa will have disastrous impacts on managed hives in the future.