Short communication: Amitraz treatments do not increase the frequency of mutations in the β2-adrenergic octopamine receptor in Varroa destructor: a field study in Central Spain

Abstract

The ectoparasitic mite Varroa destructor is a major threat to Apis mellifera colonies. Beekeepers use acaricides such as amitraz for control, but resistance has been reported, possibly linked to mutations in the Octβ2R gene. This study examined the frequency of these mutations in Varroa populations from two management systems: organic (oxalic acid treatment) and conventional (amitraz treatment). DNA was extracted individually from 83 mites collected from 14 apiaries, and a 1064 bp fragment of Octβ2R was amplified and sequenced. The F290L-related mutation appeared at a high frequency (89%), with no significant differences between treatments. No other reported mutations were found. The widespread homozygosity of F290L and lack of treatment-related variation suggest that this mutation existed before amitraz use, reflecting historical genetic variation rather than recent selection. Further research is needed to clarify its role in amitraz resistance