18
Jan
Growing Sunflowers Near Honey Bee Colonies Helps Reduce Mite Problems
(Beyond Pesticides, January 18, 2023) Sunflower plantings have the potential to significantly reduce mite infestations in nearby honey bee colonies, according to research recently published in the Journal of Economic Entomology by researchers with the U.S. Department of Agriculture (USDA). With pollinators under threat from pesticides, climate change, loss of habitat, and the spread of disease and parasites, sustainable methods that address multiple factors at once are needed. This study points to a way to address destructive Varroa mites, while reducing the need for in-hive use of miticides that can likewise harm colony health. “If sunflowers are as big of a factor in mite infestation as indicated by our landscape-level correlations … having a few more acres of sunflower within a mile or two of apiaries could bring colonies below the infestation levels that require treatment of hives with acaracides (i.e., mite-controlling chemicals),” said lead author Evan Palmer-Young, PhD, of USDA’s Bee Research Lab in Beltsville, MD.
Prior research has pointed to sunflower pollen as a potential benefit for a number of common bee diseases and infestations, including the Varroa mite, the fungal parasites Nosema spp, and various viruses. Investigations went through four different experiments aimed at characterizing any potential effects. The first focused on landscape associations between Varroa mites and Nosema using National data on over 400 apiaries in 30 states, comparing the amount of sunflower crop area to colony health. The second took a group of 30 bee colonies at the University of Maryland and supplemented their feeding with either an artificial pollen patty, sunflower patty, or wildflower patty during the late summer to early fall, and then assessing the prevalence of mites and disease. The third supplemented a group of 30 colonies in Massachusetts with the same pollen options in springtime, and then evaluated colony health. The last experiment focused on the impact of sunflower pollen on worker bees already infected with Nosema and deformed wing virus.
For the initial experiment on landscape associations, areas with more sunflower production were found to have lower levels of mite infestation. For every doubling of sunflower crop production, models employed show a nearly 1/3 decrease in varroa mite infestation. For the fall pollen feeding experiment, colonies fed sunflower pollen saw a 2.75 fold reduction in the intensity of Varroa infestation compared to the artificial pollen treatment. For the spring feeding, Varroa was found in only one-third of hives sampled. Neither the fall nor spring feed experiment, or the individual caged bee experiment saw a significant effect on viral loading or Nosema prevalence, however. “Although we did not find significant effects of sunflower pollen on endopasrasites [Nosema ceranae] or viruses in laboratory or field settings, sunflower pollen was associated with reduced levels of Varroa mites in honey bee colonies,” the authors write.
This finding is important in the context of declining diversity in U.S. crops. According to the study, the acreage of US farmland under sunflower production has declined by 2% per year since 1980.
While the pesticide industry often cites Varroa mites as the primary factor in pollinator declines, it is critical to understand that pesticides are playing a role in this phenomenon. Evidence shows that exposure to neonicotinoid insecticides increase honey bee vulnerability to mite problems. While mites infestations are relatively simple to diagnose in the field, it is much more difficult to test for insecticide exposure in a hive, requiring specialized labs and equipment.
Typical approaches to Varroa management include regular hive treatments with various miticides, many of which can likewise place a colony at risk. Any approach that will allow beekeepers to reduce stress on honey bee hives provides important benefits. “If sunflower pollen can be used to effectively manage Varroa mites, the timing of sunflower pollen production—which peaks in late summer (in temperate regions), just as mite levels begin to rise towards their peak in October and November (Traynor et al. 2016)—is ideal for reducing infestation during the critical late-season time frame,” the study notes.
Nearly a decade ago, then-President Obama established a Presidential Pollinator Health Task Force aimed at reversing declines in honey bees and other pollinators, coordinating action among various government agencies, and including guidelines for federal agencies to protect pollinators. USDA did announce some actions to increase habitat, but neglected other factors like pesticides, and only two years later, the Government Accountability Office cited USDA and the U.S. Environmental Protection Agency for its failure to address threats to pollinator populations. While the Trump administration took an antagonistic approach towards pollinator safety, siding with industry and delaying even the listing of an endangered pollinator, President Biden has yet to pick up the important work that President Obama began, or take any similar steps to protect pollinators.
With a vacuum in leadership at the top, both managed and wild pollinators continue to suffer unacceptable declines that threaten not only the health of ecosystems, but critical food sources humans rely upon. Earlier this year a study found pollinator declines are the reducing the global production of nuts, fruits, and vegetables by 3-5% annually, and this loss of healthy, nutrient-dense food is resulting in over 425,000 excess deaths each year.
Join Beyond Pesticides in urging the Biden administration to take meaningful steps to reform pesticide regulation and address the coinciding existential crises of our time – climate change, public health, and pollinator and biodiversity decline.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source: Entomology Today, Journal of Economic Entomology
