Parasitas e comportamento higiênico em colônias de Apis mellifera no Recôncavo Baiano

Abstract

Similar to all living organisms, bees can be attacked by parasites and pathogens, which can lead to colony loss. Among these, the mite Varroa destructor and microsporidium Nosema spp. are indicated as causing of colony losses in Apis mellifera. As a defence mechanism, bees have the so-called hygienic behavior (HB), which is important for the control of parasites and pathogens in the colony. Therefore, studying parasites that may be affecting Africanized bees, as well as their natural defence mechanism is a necessity, since these insects are important economically, socially, and mainly, ecologically. The objective of this study was measure the degree of hygienic behavior in africanized bees A. mellifera, as well as to evaluate the presence of the V. destructor mite and the microsporidia Nosema spp., in apiary located in the Reconcavo Baiano. The number of spores of Nosema spp. was evaluated by microscopy in 14 different colonies during the months of Oct 2016 to May 2017. The HB was evaluated by average of dead pupae exposure and evaluation after 24 h in 10 colonies during five weeks and in two different periods. The quantification of the V. destructor infestation level was evaluated by the number of mites versus the number of honeybees per sample. Ten colonies of A. mellifera were evaluated between Oct 2018 and Mar 2019. Climatic data were obtained from Climate-Data and used for comparison with the results of Nosema spp. and V. destructor in the different evaluated months. The results were evaluated by the Kruskal-Wallis test at 5% significance level. Finally, Pearson's correlation was used to evaluate the possible interaction of environmental versus parasite factors. All A. mellifera colonies presented positive results for Nosema spp and V. destructor. The amount of spores of Nosema spp. as well as the level of infestation by V. destructor can be considered low and it is still observed that the climatic conditions of the region can positively or negatively impact the incidence of these two parasites. The bees presented variable HB according to the colony and period studied, being this higher in the second evaluation period. In this study it was observed that the parasites Nosema spp. and V. destructor are present in A. mellifera and that environmental parameters may influence the increase of these parasites in bees. Finally, the study showed that the HB in africanized honeybees can be variable according to the population of the colony, period of the year and generation of bees that is dominant in the colony, ranging from absent to present. The results evidenced the importance of monitoring and knowledge of the hygienic behavior pattern in A. mellifera, since this behavior is vital to avoid the loss of colonies and consequently ecological and economic damages.