Índice de infestação do ácaro Varroa destructor e comportamento higiênico em colônias de abelhas Apis mellifera L. em Alagoas

Abstract

The present work aimed at evaluating Varroa destructor infestation rates and its correlation to hygienic behavior in colonies of Africanized honeybees. The experiment was undertaken in two apiaries, one belonging to the municipality of Rio Largo and the other to the municipality of União dos Palmares, both located in the region called Zona da Mata, Alagoas State. Twelve colonies settled in Langstroth hives were used. Six colonies were randomly chosen for evaluation in each apiary. The variables analyzed were: Varroa infestation rates in brood and adult bees and the hygienic behavior of the colonies. Adult bees (300 per colony) were collected and placed in vials containing alcohol at 70% and shipped to the lab for parasite evaluation. A piece of comb with capped brood was taken from each colony to screen for mites on brood. Hygienic behavior was assessed using the pierced brood method. We evaluated those parameters in two distinct periods, i.e. at the beginning of the nectar flow and after the harvest. Varroa destructor was found in all colonies. The higher numbers of mites were found in the colonies belonging to the municipality of Rio Largo (7.66 % and 70% for adult bees and brood, respectively). In the municipality of União dos Palmares mite numbers were (2.98% and 28% for adult bees and brood, respectively). We believe that environmental factors like the shortage of adequate pollen as well as the large use of pesticides sprayed over sugar cane plantations in the surroundings of Rio Largo ́s apiary might have contributed to the higher numbers of mites found there. In both apiaries colonies present the better hygienic behavior in sunny days and during the nectar flow period. We did not find any correlation between hygienic behavior and Varroa infestation of adult bees (r= 0,02200; p > 0,05) and brood (r= 0,07890; p > 0,05). Taking into account all the factors that might influence mite infestation as well as the expression of hygienic behavior in bee colonies, we could not say with the present study that this natural defense mechanism of Africanized honeybees isn ́t efficient to the attack of Varroa destructor.