Varroa destructor in Juquitiba, Vale do Ribeira, Southeastern Brazil: Seasonal Effects on the Infestation Rate of Ectoparasitic Mites on Honeybees

Abstract

We evaluated the infestation rate (IR) of the ectoparasite mite Varroa destructor in hives of the Africanized honeybee Apis mellifera in 10 commercial apiaries located in the municipality of Juquitiba (Vale do Ribeira, São Paulo, Brazil) during two seasons (summer and winter). From each apiary, three colonies were randomly selected for collection of bee samples in each season. The average mite IR was 7.3%, when pooling both seasons. For the summer period the average IR varied from 1.1 to 11.6% (KW = 25.9191; p < 0.01). For the winter period, IR values were observed ranging from 0.3 to 19.1% (KW = 18.7760; p < 0.05). In only three of the studied apiaries did the IR remain unchanged over both seasons, even though it tended to be higher during the winter period for the other apiaries. The mean IR of V. destructor was considered too small to cause any considerable loss to the colonies. Nevertheless, it is necessary to monitor the mite IR over longer periods of time to detect the most resistant hives and avoid future problems.