Haley McBroom

234 Haley McBroom

Immunity: Threats to Bee Colonies and Methods to Defend Against the Threats

 Every year since 2006, more than thirty percent or more of the beehives in the United States have been killed annually due to a wide range of apicultural threats.¹ This high mortality rate presents a significant problem because honey bees contribute almost $20 billion to the agricultural economy.² By providing invaluable ecosystem services through their pollination of diverse plants. A whole host of agents contribute to these devastating mortality rates. Beekeepers must minimize the devastating mortality that bee populations are suffering by experiencing apiary management and by working in synergy with the natural resilience and innate methods various strains of honey bees possess.

This paper will examine two of these threats, varroa mites and American foulbrood and the adaptive mechanisms they possess to aid in their survival of these two pathogens. These mechanisms provide honey bee queen breeders with opportunities to develop genetically resistant stock, thus potentially reducing reliance on antibiotics and miticides and enhancing overall bee resiliency.

Varroa mites are the number one cause of bee mortality in the U.S.³ This ectoparasite originated in Asia and has spread throughout most of the planet. Varroa mites feed on the hemolymph of developing brood, resulting in deformities and behavioral maladaptations.⁴ Furthermore, varroa mites serve as vectors for other pathogens like deformed wing virus. To effectively manage varroa mites, beekeepers should monitor their hives vigilantly to be sure that the mite numbers do not exceed 2-3 mites per 100 bees in order to prevent catastrophic brood destruction.⁵ Excessively infested hives can be treated with an appropriate miticide in order to save these colonies.

Fortunately, certain strains of honey bees have natural behaviors to defend against varroa mites. First, bees can bite mite appendages on other infected bees. This grooming behavior damages the mite, and it will either drop off or not be able to reproduce and damage additional brood in the hive.⁶ Next, some strains of honey bees can detect mites on brood and can remove infected brood from the hive, reducing mite reproduction rates. These two traits have been found to be heritable, so queen breeding programs have focused on these and other mechanisms resulting in varroa sensitive hygiene (VSH) bees. There are several VSH queen lines readily available to beekeepers today. A third behavior bees use that helps control varroa mites involves frequent swarming. This results in the daughter swarm having lower mite counts since most of the mites remain on brood in the parent colony. Although not beneficial to beekeepers and thus is of limited agricultural value, swarming does allow naturalized populations of honey bees to gain some competitive advantage over varroa mites.

A second significant threat to bee colonies, American foulbrood (AFB), is a bacterial disease that kills developing brood and produces large numbers of long-lived, resistant spores that can readily spread. Worker bees disseminate AFB spores beyond the hive, and workers from other colonies bring spores back to their hive, resulting in widespread, rapid devastation of bee populations.⁷ If AFB is confirmed in a hive, beekeepers must exterminate the colony and burn infected combs. Antibiotics are used to control AFB to a large extent, though there is concern about AFB developing antibiotic resistance.⁸

While AFB is a highly contagious and damaging pathogen, bees use natural defenses they possess to help control this bacteria. First, the ability of pollen to retard bacterial growth known as food inhibition can result in reduced intestinal infection rates. Specific probiotics and beneficial microorganisms contained in certain pollen can significantly reduce AFB’s reproduction in the bee gut.¹⁰ Next, particular AFB inhibitory peptides have been found in royal jelly, imparting greater bacterial resistance to young brood.¹¹ Certain varieties of honey bees are bred to prefer and utilize food inhibition and royal jelly peptides preferentially, and this characteristic may be heritable. The third and most promising mechanism at this time for improving AFB resistance involves hygienic behavior. Some honey bee varieties are able to detect AFB infected larvae and remove them from the colony. This reduces the rate of spread to the rest of the hive.¹² While this behavior has been found to be heritable, AFB hygienic queens are not commercially available at this time.¹³

Bee scientists and queen breeders have made significant progress in developing ways to minimize the spread of varroa mites and AFB, yet beekeepers must nonetheless employ vigilant oversight throughout their apiary to combat these and numerous other threats to their colonies. Because it is often the case that these threats work synergistically in a vicious cycle of destruction, successful hive maintenance requires a holistic view of bee health, including careful monitoring of sub-lethal pesticide residues to be sure they don’t suppress the colony’s immune system and thus reduce its natural defense mechanisms. These concerns notwithstanding, the dynamic science of honey bee health and genetics promises beekeepers the necessary tools for increasing colony survival ensuring the supply of delicious and nutritious honey, and enabling honey bees to continue pollinating some of the world's most valuable agricultural crops well into the future.

Notes:

  1. usda.gov. 2021. Conservation Work for Honey Bees | NRCS. [online] Available at:<https://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/plantsanimals/pollinate/?cid= stelprdb1263263> [Accessed 13 March 2021].https://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/plantsanimals/pollinate/?cid=st elprdb1263263
  1. (n.d.). Retrieved March 13, 2021, from https://www.abfnet.org
  1. Oliver, “The Varroa Problem: Part 1.” American Bee Journal, vol. 156, no. 11, 2016, pp. 1233-1238.
  1. IBID
  1. Oliver, “The Varroa Problem: Part 14, Virus Dynamics and Treatments.”American Bee Journal, vol. 18, no. 1, 2018, pp. 69-74.
  1. Underwood, R., & López-Uribe, M. (2021, March 08). Methods to control varroa mites: An integrated pest management approach. Retrieved March 13, 2021, from https://extension.psu.edu/methods-to-control-varroa-mites-an-integrated-pest-managemen t-approach https://extension.psu.edu/methods-to-control-varroa-mites-an-integrated-pest-managemen t-approach
  1. Brødsgaard & H. Hansen 2003. Tolerance mechanisms against American foulbrood in honeybee larvae and colonies Apiacta 38: 114–124 http://www.fiitea.org/foundation/files/2003/Brodsgaard.pdf
  1. Spivak, M., & Reuter, G. (1970, January 01). Resistance to American FOULBROOD disease by honey bee Colonies Apis mellifera bred for HYGIENIC behavior. Retrieved March 13, 2021, from https://experts.umn.edu/en/publications/resistance-to-american-foulbrood-disease-by-hon ey-bee-colonies-ap
  1. Medicine, C. (n.d.). Veterinary feed directive producer requirements. Retrieved March 13, 2021, fromhttps://www.fda.gov/animal-veterinary/development-approval-process/veterinary-feed-dir ective-producer-requirementshttps://www.fda.gov/animal-veterinary/development-approval-process/veterinary-feed-dir ective-producer-requirements
  1. Brødsgaard & H. Hansen 2003. Tolerance mechanisms against American foulbrood in honeybee larvae and colonies Apiacta 38: 114–124 http://www.fiitea.org/foundation/files/2003/Brodsgaard.pdf

  2. http://www.beelab.umn.edu/sites/beelab.umn.edu/files/resistance-foulbrood.pdf
  1. Medicine, C. (n.d.). Veterinary feed directive producer requirements. Retrieved March 13, 2021, fromhttps://www.fda.gov/animal-veterinary/development-approval-process/veterinary-feed-dir ective-producer-requirements https://backyardbeekeeping.iamcountryside.com/health-pests/hygienic-bees-smell-disease/
  1. https://www.nj.gov/agriculture/divisions/pi/pdf/AFBfactsheet.pdf

Works Cited:

  1. usda.gov. 2021. Conservation Work for Honey Bees | NRCS. [online] Available at:<https://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/plantsanimals/pollinate/?cid= stelprdb1263263> [Accessed 13 March 2021].
  1. d.). Retrieved March 13, 2021, from https://www.abfnet.org
  1. Oliver, “The Varroa Problem: Part 1.” American Bee Journal, vol. 156, no. 11, 2016, pp. 1233-1238.
  2. Underwood, R., & López-Uribe, M. (2021, March 08). Methods to control varroa mites: An integrated pest management approach. Retrieved March 13, 2021, from https://extension.psu.edu/methods-to-control-varroa-mites-an-integrated-pest-managemen t-approach
  3. Brødsgaard & H. Hansen 2003. Tolerance mechanisms against American foulbrood in honeybee larvae and colonies Apiacta 38: 114–124
  4. Spivak, M., & Reuter, G. (1970, January 01). Resistance to American FOULBROOD disease by honey bee Colonies Apis mellifera bred for HYGIENIC behavior. Retrieved March 13, 2021
  5. Medicine, C. (n.d.). Veterinary feed directive producer requirements. Retrieved March 13, 2021, fromhttps://www.fda.gov/animal-veterinary/development-approval-process/veterinary-feed-dir ective-producer-requirements
  1. http://www.beelab.umn.edu/sites/beelab.umn.edu/files/resistance-foulbrood.pdf
  1. https://www.nj.gov/agriculture/divisions/pi/pdf/AFBfactsheet.pdf

Biography:

To whom it may concern:

My name is Haley McBroom. I am a senior at Regents Academy in Nacogdoches, TX. I live at 1173 CR 2734, Alto, TX, 75925. My family owns and operates Wildhurst Apiaries, In which I assist with hive management, honey harvesting and bottling, and sales and marketing. This year we are putting in 300 VSH Minnesota Hygienic queen cells into our March splits. My email address is

 , and my phone number is 936-867-0027.

 Photos:

McBroom 4
McBroom 1 McBroom 3 

These photos were taken at one of Wildhurst Apiaries hive yards in Milam, Texas. Photos taken by Haley McBroom.

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