Resistance to amitraz in the parasitic honey bee mite Varroa destructor is associated with mutations in the B-adrenergic like octopamine receptor

Authors: HERNANDEZ-RODFIGUEZ, CARMEN - University Of Valencia; MORENO-MARTI, SARA - University Of Valencia; ALMECIJA, GABRIELLE - National Center For Scientific Research; CHRISTMON, KRISZTINA - University Of Maryland; Johnson, Josephine; VENTELON, MARIE - (NCE, CECR)networks Of Centres Of Exellence Of Canada, Centres Of Excellence For Commercilization A; VANENGELSDORP, DENNIS - University Of Maryland; Cook, Steven; GONZALES-CABRERA, JOEL - University Of Valencia

Submitted to: Journal of Pest Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/9/2021
Publication Date: 12/23/2021
Citation: Hernandez-Rodfiguez, C.S., Moreno-Marti, S., Almecija, G., Christmon, K., Johnson, J., Ventelon, M., Vanengelsdorp, D., Cook, S.C., Gonzales-Cabrera, J. 2021. Resistance to amitraz in the parasitic honey bee mite Varroa destructor is associated with mutations in the B-adrenergic like octopamine receptor. Journal of Pest Science. https://doi.org/10.1007/s10340-021-01471-3.
DOI: https://doi.org/10.1007/s10340-021-01471-3

Interpretive Summary: Varroa destructor is a harmful ectoparasitic mite of Apis mellifera honey bees. Beekeepers must monitor and treat colonies with pesticides against Varroa to avoid complete loss of honey bee colonies. Commonly used pesticides have active ingredients belonging to the organophosphate, pyrethroid and Formamide classes of chemical pesticides. Unfortunately Varroa have gained resistance to the two former types of pesticides, and evidence from different regions of the world suggest that amitraz, a formamide pesticide, has begun losing its efficacy against Varroa mites. To investigate the mechanism of the resistance to amitraz detected in Varroa obtained from French and U.S. apiaries, we identified and characterized octopamine and tyramine receptors (the known targets of amitraz) in Varroa. The comparison of sequences obtained from mites collected from different apiaries with different treatment regimens, showed that the amino acid substitutions N87S or Y215H in the Beta-Octopamine receptor were associated with treatment failures reported in French of U.S. apiaries, respectively. Further, a high-throughput assay using commercially available molecular biological materials (TaqMan(R)) was developed that quickly and accurately identifies Varroa with these mutations. The implications of Varroa gaining full resistance to amitraz-based varroacides is a frightening prospect to beekeepers but understanding the underlying mechanisms of resistance to these pesticides would give researchers the tools and information necessary to monitor resistance and avoid developing novel varroacides that have similar modes of action.

Technical Abstract: Varroa destructor is considered a major reason for high loss rate of Western honey bee (Apis mellifera) colonies. To prevent colony losses caused by V. destructor it is necessary to actively manage the mite population. Beekeepers, particularly commercial beekeepers, have few alternative treatments other than synthetic acaricides to control the parasite, resulting in intensive treatment regimens that led to the evolution of resistance in mite populations. To investigate the mechanism of the resistance to amitraz detected in V. destructor mites from French and U.S. apiaries, we identified and characterized octopamine and tyramine receptors (the known targets of amitraz) in this species. The comparison of sequences obtained from mites collected from different apiaries with different treatment regimens, showed that the amino acid substitutions N87S or Y215H in the OctB receptor were associated with treatment failures reported in French of U.S. apiaries, respectively. Based on our findings, we have developed and tested two high throughput diagnostic assays based on TaqMAn (R) able to accurately detect mites carrying the mutations in this receptor. This valuable information may be of help for beekeepers when selecting the most suitable acaricide to manage V. destructor.