AN ASSAY TO DETECT FLUVALINATE RESISTANCE IN VARROA MITES

A field assay was developed to screen Varroa mites for resistance to f luvalinate (Apistan(R))(1). The assay relies upon a comparison in mite drop between 2.5% and 10% fluvalinate using paired samples of live ad ult honey bees from the same colony. Two samples from each of 10-12 co lonies were collected per apiary and bees were held in jars for 24 hou rs at 75-95 degrees F. After 24 hours, mite fall was recorded and the number of mites remaining on bees was determined. Percent mortality wa s calculated for each concentration. Results from tests in four states revealed that when mites were susceptible to fluvalinate (controlled with Apistan(R) in 3-4 weeks) they had nearly equal mite fall and perc ent mortality was above 85% for both concentrations. In contrast, mite s deemed resistant (from colonies where Apistan did not provide contro l) exhibited large concentration-dependent differences in mite fall, w ith percent mortality less than 30% and 50% for the 2.5 and 10% concen trations, respectively. The assay was designed to enable beekeepers to assess Varroa populations for resistance to fluvalinate and is useful in predicting anticipated control.