Resistance of Africanized bees (Apis mellifera L.) as a cause of mortalityof the mite Varroa jacobsoni Oud. in Brazil

Apis mellifera honey bees of African origin and their hybrids usually prese nt greater tolerance of the parasite Varroa jacobsoni compared to honey bee s of European races. Several mechanisms have been proposed to explain the l ow infestation of these bees by the Varroa pest. The objective of the prese nt study was to determine the mortality rate of the varroa parasite and its relationship with proportion of mites versus adult bees. The study was con ducted on ten colonies (nuclei) of Africanized bees under the climatic cond itions of Blumenau, State of Santa Catarina, Brazil. The mortality rate of Varroa jacobsoni was estimated from the daily number of dead mites found at the bottom of the hive and from an estimate of the total mite population o f each hive. Mean daily mortality of the mites was 1.85%, i.e., almost 2% o f the varroa population died daily. A high correlation was detected between mortality rate and the proportion of mites versus number of adult bees exi sting in each bee colony (r = -0.83; P<0.001).