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

Background Managed honey bees are key pollinators of many crops and play an essential role in the United States food production. For more than 10 years, beekeepers in the US have been reporting high rates of colony losses. One of the drivers of these losses is the parasitic mite Varroa destructor. Maintaining healthy honey bee colonies in the US is dependent on a successful control of this mite. The pyrethroid tau-fluvalinate (Apistan®) was among the first synthetic varroacides registered in the US. With over 20 years of use, mites resistant to Apistan® have emerged, and so it is unsurprising that treatment failures have been reported. Resistance to tau-fluvalinate in US mite populations is associated with point mutations at position 925 of the voltage-gated sodium channel. Results Here, we have generated a distribution map of pyrethroid resistance alleles in Varroa samples collected from US apiaries in 2016 and 2017, using a high throughput allelic discrimination assay based on TaqMan®. Our results evidence that kdr-type mutations are widely distributed in Varroa populations across the country showing high variability among apiaries. We used these data to predict the phenotype of the mites in case of treatments with pyrethroids. Conclusion We highlight the relevance of monitoring the resistance in mite populations to achieve an efficient control of this pest. We also put forward the benefits of implementing this methodology to provide data for designing pest management programs aiming to control Varroa. This article is protected by copyright. All rights reserved.