Population dynamic of Varroa Destructor in the local honey bee Apis Mellifera Intermissa in Algeria

Abstract

Population dynamics of Varroa destructor were studied for two years (septembre 2012– 2014) in 20 Apis mellifera intermissa colonies located in Blida (center of Algeria). The number of bees, the amount of open brood and capped, daily natural mortality, level of infestation of adult bees and level of infestation of the brood, was monitored.

The brood cycle and behavior of reproduction in Apis mellifera intermissa is set by exceptional and seasonal contrasts in climate: dry summer (June to September), with an almost complete stop brood. Autumn, relatively wet causes a second peak of activity and brood development. The values of the infestation rate of brood and bees show peaks in August, this period when there is the minimum amount of both bees and brood in the colony. In all colonies, the population of Varroa presented during the spring curve of exponential growth, which is explained by the continued presence of brood. In the growth phase, followed by a collapse of populations of mites, which in our experimental conditions, occurred from early summer, along with a weakening of colonies phase. Successive brood cycles allow the population growth of Varroa, while the absence of brood during the summer months has the opposite effect of reducing populations of Varroa. It appears that the level of Varroa infestation in colonies varies according to climatic conditions (seasonal) and internal conditions of each colony. In Mediterranean climates of Algeria, the milder winter climatic conditions and the possibility to collect food resources during a considerable part of the winter count for the permanent brood-rearing activity of honey bee colonies, which is relevant for the intrinsic growth rate of Varroa in these regions.