Large-scale monitoring of resistance to coumaphos, amitraz and pyrethroids inVarroa destructor

Abstract

Varroa destructor is an ectoparasitic mite causing devastating damages to honey bee colonies around the world. Its impact is considered a major factor contributing to the significant seasonal losses of colonies recorded every year. Beekeepers are usually relying on a reduced set of acaricides to manage the parasite, usually the pyrethroids tau-fluvalinate or flumethrin, the organophosphate coumaphos and the formamidine amitraz. However, the evolution of resistance in the populations is leading to an unsustainable scenario with almost no alternatives to reach an adequate control of the mite.Here we present the results from the first, large-scale and extensive monitoring of the susceptibility to acaricides in the Comunitat Valenciana, one of the most prominent apicultural regions in Spain. Our ultimate goal was to provide beekeepers with timely information to help them decide what would be the best alternative for a long-term control of the mites in their apiaries. Our data show that there is a significant variation in the expected efficacy of coumaphos and pyrethroids across the region, indicating the presence of a different ratio of resistant individuals to these acaricides in each population. On the other hand, the expected efficacy of amitraz was more consistent, although slightly below the expected efficacy according to the label.HIGHLIGHTSVarroa destructor is causing severe damages to honey bee colonies worldwide.There are very few acaricides available to manage the parasite.The evolution of resistance is limiting our capacity to control the mite.We estimated the expected efficacy of the main acaricides in many Spanish apiaries.The information was shared with beekeepers for them to decide the best treatment to control the mite.

Mutations associated with pyrethroid resistance in Varroa mite, a parasite of honey bees, are widespread across the United States

“…Resistance to pyrethroids in V. destructor is associated with mutations at position 925 of the VGSC. The mutation L925V, a mutation found in European mites, [53][54][55][57][58][59]69,70 was not detected in the United States, rather the mutations L925I and L925M were wide spread (Fig. 2).…”

“…43,[49][50][51][52] In resistant Varroa mites from Europe, the mutation found associated with kdr-type resistance to pyrethroids is the substitution from the wild-type leucine to valine at position 925 of the channel protein (L925V) (numbered after the housefly para-type sodium channel protein). [53][54][55][56][57][58] But in the United States, kdr-type mutations in Varroa are associated with isoleucine (L925I) or methionine (L925M) substitutions of the wild-type leucine at the same position. 59,60 Early detection of mutations associated with resistance could be a useful tool for beekeepers wanting to prevent treatment failures.…”

“…This method has been demonstrated to be robust, reliable, and fast for genotyping large number of mites individually, hence able to determine the incidence of pyrethroid resistant and susceptible mites in a given apiary. 57,59,69 While several surveys have explored the distribution of mutations associated with pyrethroid resistance in Europe, 55,56,58,[69][70][71] there is very limited information of the situation in the United States, with only one report showing the presence of the mutations in mites collected from Florida and Georgia. 59 Here, using the high-throughput diagnostic tool with mites sampled in 2016 and 2017, we have generated a distribution map of pyrethroid resistance mutations across the United States.…”

A systematic review of honey bee (Apis mellifera, Linnaeus, 1758) infections and available treatment options

“…The artificial selection for drug resistance of mite populations with the constant use of these treatments occurs quite rapidly as well. Under such circumstances, the overuse of these products unfortunately resulted in a decreased efficiency (< 50%) or the total lack of efficacy against Varroa infestations all together (Hernandez et al, 2021;Richard et al, 2012).…”