Minimizing exposure: using Integrated Pest Management (IPM) to reduce beekeeper-applied chemicals

Honey bee hives are not just homes for bees. Colonies also host numerous pathogens, parasites and pests. Managing hive health is a challenge for modern beekeepers who must monitor for multiple hive enemies. Beekeeper-applied chemicals are often temporarily successful in repressing select diseases and pests. Once treatments wear off, however, the same hive enemies frequently resurface. In some cases, widespread and repeated chemical use by beekeepers has led to the emergence of resistant diseases and pests. Furthermore, many treatments aimed at disease and pest control also have hidden health costs for bees. Finally, pesticide exposure and poor nutrition caused by habitat loss have created a hostile landscape for bees and other pollinators. These threats stress colonies, making honey bees more susceptible to infection, and ironically, perhaps vulnerable to the very chemicals that beekeepers use to treat hive enemies. Beekeepers can minimize the costs of some of these threats by using Integrated Pest Management (IPM) strategies to control hive enemies. Under an IPM plan, beekeeper chemicals are applied judiciously and used in combination with other control strategies.

Historically, many beekeepers proactively applied chemicals regardless of whether their colonies were diseased. However, beekeepers incur unnecessary expenses when they apply treatments to healthy colonies or colonies with low, non-threatening levels of diseases or pests. Indiscriminate chemical use also selects for resistant hive enemies. For example, North American beekeepers routinely used antibiotics to suppress American Foulbrood (Paenibacillus larvae) infections without supervision for decades.1,2 Lax regulation of antibiotics led to the appearance of antibiotic-resistant strains of this devasting disease. The Veterinary Feed Directive, which regulates antibiotic use in animals, was modified in 2017, and beekeepers now need veterinary supervision to treat honey bee colonies with medically important antibiotics.3 Widespread chemical use has also already led to the emergence of regionally resistant strains of newer, introduced parasites like varroa mites.4,5

Beekeeper-applied chemicals are intended to narrowly target hive enemies. However, these same chemicals can have negative side effects in bees. For example, varroa mites are evolutionarily related to bees. Thus, it is difficult to find chemicals (organic or synthetic) that kill mites without harming bees. Not surprisingly, commonly applied miticides can negatively affect many aspects of colony health and reproduction.6–8 Bees are also exposed to pesticides outside of the colony and can bring these chemicals back to the hive in pollen and nectar. Though external pesticides are intended to control pest insects, weeds, and fungi, low doses can still harm bees. There is also potential for beekeeper-applied chemicals to interact with each other and the pesticides that bees bring into the hive, producing unintended consequences for bee health.9

varroa monitoring board

IPM plans for honey bee diseases and pests reduce the historic problems associated with beekeeper-applied chemicals. All IPM plans require beekeepers to monitor their colonies and apply appropriate chemical treatments when hive enemies are present at damaging levels. This ensures that chemicals are only administered when needed, reducing bee exposure and the chances that hive enemies will develop resistance. IPM plans also recommend the use of multiple management strategies before resorting to chemicals. General preventative measures like throwing out old comb that has accumulated pesticides and pathogens or improving colony nutrition can strengthen colonies, enabling them to naturally resist enemies. Other strategies might include trapping pests. Longer-term solutions include the selective breeding and use of honey bees that display behavioral or physiological resistance traits. IPM plans are constantly progressing as new, scientifically based approaches are developed. Using IPM to control hive enemies offers beekeepers a sustainable way to use chemicals in the face of evolving threats.

How can you make IPM part of your honey bee husbandry practice?

  1. Learn about IPM for bees. Beekeepers are responsible for learning how to recognize the signs and symptoms of bacterial, viral or fungal diseases and how to identify parasites and pests like varroa mites, small hive beetles and wax moths. There are many online IPM resources that can help you learn how to identify and manage hive enemies. Penn State offers an online beekeeping course and provides links to other materials. Your local university extension program or beekeeping chapter may also offer classes and regionally tailored materials.
  2. Ask an expert. You can seek help from your local university's extension program or your State Apiculturist. Experts may be able to examine your hive in person or review pictures and then point you in the direction of appropriate resources.
  3. Use diagnostic services. You can send colony samples to the USDA Bee Research Laboratory. The laboratory will identify some pathogens, parasites and pests. This is a free service (aside from the cost of postage).
  4. Follow chemical treatment instructions. If applying a chemical treatment is part of your IPM plan, make sure to follow the label instructions for your health and safety as well as that of the bees! You may need veterinary supervision for some treatments. Continue to monitor following treatment to make sure that the treatment was effective.
  5. Participate in citizen science. Help define national trends in honey bee colony health and identify effective management strategies by participating in citizen science. You can provide data to programs like the Bee Informed Partnership.

References

  1. Locke, B., Low, M. & Forsgren, E. An integrated management strategy to prevent outbreaks and eliminate infection pressure of American foulbrood disease in a commercial beekeeping operation. Prev. Vet. Med. 167, 48–52 (2019).

  2. Lopez-Uribe, M. & Underwood, R. Honey bee diseases: American foulbrood. Penn State Extension (2019 (Accessed: 26th September 2020)

  3. U.S Food and Drug Administration. Using Medically Important Antimicrobials in Bees - Questions and Answers. Development and Approval Process (2017). (Accessed: 20th September 2020)

  4. Rinkevich, F. D. Detection of amitraz resistance and reduced treatment efficacy in the Varroa Mite, Varroa destructor, within commercial beekeeping operations. PLoS One 15, e0227264 (2020).

  5. Underwood, R. & Lopez-Uribe, M. Methods to control varroa mites: an integrated pest management approach. Penn State Extension (2019). (Accessed: 26th September 2020)

  6. Rangel, J. & Tarpy, D. R. The combined effects of miticides on the mating health of honey bee (Apis mellifera L.) queens. J. Apic. Res. 54, 275–283 (2015).

  7. Fisher II, A. & Rangel, J. Exposure to pesticides during development negatively affects honey bee (Apis mellifera) drone sperm viability. PLoS One 13, e0208630 (2018).

  8. Tihelka, E. Effects of synthetic and organic acaricides on honey bee health: a review. Slov. Vet. Res. 55, 119–40 (2018).

  9. Mullin, C. A. et al. High Levels of Miticides and Agrochemicals in North American Apiaries: Implications for Honey Bee Health. PLoS One 5, e9754 (2010).