Genetic and morphometry variation of the Varroa destructor developing in standardand small comb cells

摘要

The Varroa destructor mite is regarded as the main causative agent of Colony Collapse Disorder (30, 31). The mite body size (width 1708.9 u.m, length 1167.3 ycm) (2) enables it to parasitize bee broods in a way that is difficult for bees to discover.The mite causes deformations in bees and a decrease in their body weight (6, 24, 26), which is the result of loss of the fat-protein body in the brood (7, 8). Reduced body weight leads to a decline in flight efficiency and vitality, as well as in a lossof navigation ability in adult bees (1, 6, 8, 9, 11, 12, 23, 27). Moreover, Varroa destructor is a biological vector for viruses, which replicate in their organisms (4,19). Bees that are infested by the virus-infected mites exhibit high mortality rates.Consequently, entire colonies usually die within 6 months up to 2 years (22, 33). At present, there are no fully satisfactory methods of varrosis control. This is because of increasing resistance of Varroa destructor to varroacides (10). Therefore, the continuous monitoring of bee colonies' infestation by counting mitesthat have died from both a natural death and upon application of varroacidal agents is important. Developing of a scheme of alternate application of curative agents is also of the greatest importance (3). One of the ways to control mites is to employ ofa biological method, which involves use of 4.9 mm small-cell combs (21). Unlike in standard sized cells (5.4 mm), a considerably larger number of Varroa females seem not to undergo the full developmental cycle in small sized cells, as bigger numbers of immature mites have been found among the specimens that died a natural death (18).