United States Department of Agriculture
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Varroa Mites


Project Leader: William MEIKLE


Varroa mites, Varroa destructor Anderson and Trueman, probably originated in East Asia, where they are relatively innocuous parasites of the Eastern honey bee, Apis cerana. Varroa mites were first described in 1904 as Varroa jacobsoni Oudemans but were recently found to be a complex of at least two species. Of the two, V. destructor was identified as the species causing damage to the western honey bee, A. mellifera mellifera, which is used worldwide for honey, wax production and pollination. V. destructor was found in continental Europe, northern Africa and South America by 1975 and in the U.S. in 1987. Infested colonies often die within two years. The mites do not cause massive acute mortality, but weaken larvae and adults by feeding on haemolymph, transmitting diseases, and inducing deformities. The impact of varroa mites on both domesticated and feral colonies of A. mellifera in the U.S. is difficult to exaggerate; feral populations of A. mellifera, once common, have been almost completely eliminated by the mites. The loss of wild colonies of A. mellifera has been felt most by farmers who depend on the bees for the pollination of fruit and field crops.

Research has indicated that entomopathogenic fungi may provide an effective, pesticide-free way to control varroa. Here at EBCL we have conducted exploration for isolates of entomopathogenic fungi, and used fungi found on mites in beehives in field experiments. Results are incomplete but promising. In order to better evaluate the impact of the fungi on varroa mite numbers and on hive health, we have also been working on developing ways of monitoring hive health, such as placing hives on electronic balances linked to dataloggers.