The parasitic mite, Varroa destructor, is the single most damaging biotic factor affecting the health of honey bees (Apis mellifera) and is responsible for the death of millions of honey bee colonies worldwide. The varroa mite is a tick-like parasite that feeds on the blood and fat tissue of immature and adult bees, inhibits their immune responses and can transmit viral diseases, which in turn may kill the bees. Additionally, varroa mite parasitism results in substantial reductions of honey yields of colonies. Currently, beekeepers rely on synthetic miticides, medicines to control the mites. However, the frequent use of synthetic miticides in hives has resulted in mites developing resistance to the chemical components of these products. The use of synthetic miticides has also caused contamination of hive products such as honey and wax, which may pose a health threat for human consumers or for the bees in the hive. Therefore, the identification of new compounds with high miticidal activity and low toxicity to honey bees that at the same time do not leave harmful chemical residues in hive products is an important task for bee researchers.
In a study published in the journal Experimental and Applied Acarology, our research team determined the efficacy of natural compounds including oregano oil, against varroa mites. Oregano oil was delivered with electric vaporizers and it killed more than 97% of the mites without negative effects on bee health. Additionally, most mites were killed in the first two weeks of treatment compared to the last two weeks in colonies of other treatments. These results demonstrate the importance of continuously releasing natural miticides to achieve safe and high rates of mite control in hives. They also show that a natural and safe compound like oregano oil may be an effective miticide against varroa mite infestations in colonies. Affordable and efficient vaporizers would need to be manufactured to make this treatment practical and applicable for most beekeepers, thus, our team is aiming at finding help from engineers to design such devices for future studies.
In addition to vaporizers, other oregano oil distribution methods have been researched in conjunction with the Honey Bee Research Centre. These include wet and dry methods of distribution using different mediums and processes. Each method was of varying success and all are discussed in Evaluation of Dry and Wet Formulations of Oxalic Acid, Thymol, and Oregano Oil for Varroa Mite (Sabahi et al.).
Sabahi, Q., H. Gashout, P.G. Kelly, E. Guzman-Novoa. 2017. Continuous release of oregano oil effectively and safely controls Varroa destructor infestations in honey bee colonies in a northern climate. Experimental and Applied Acarology72 (3): 263-275. Doi: 10.1007/s10493-017-0157-3.
Sabahi, Q., Morfin, N., Emsen, B., Gashout, H. A., Kelly, P. G., Otto, S., Merrill, A. R., & Guzman-Novoa, E. (2020). Evaluation of Dry and Wet Formulations of Oxalic Acid, Thymol, and Oregano Oil for Varroa Mite (Acari: Varroidae) Control in Honey Bee (Hymenoptera: Apidae) Colonies. Journal of Economic Entomology, 113(6), 2588–2594. https://doi.org/10.1093/jee/toaa218