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United States Department of Agriculture

Agricultural Research Service

Abstract of Dissertation
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Title: Studies on the control, behavior, and molecular markers of the tracheal mite (Acarapis woodi (Rennie)) of honey bees Hymenoptera: Apidae). 

Abstract: The endoparasitic mite, Acarapis woodi (Rennie), a pest of honey bees Apis mellifera L., infests most bee colonies in the United States and has been responsible for 60% of colony losses. Under field conditions, patties made from solid vegetable shortening and white sugar, with or without the addition of an antibiotic, depressed mite populations when applied continuously to bees. Treatment was significant (Site 1, F2,165=14.95; P<0.001; Site 2, F2,96=5.541; P<0.001).

To understand why shortening/sugar patties gave bees some protection, mite behavior was videotaped on callow bees (<4 days old), dead bees and bees exposed to an oil patty. Two behaviors were observed and more closely studied. “Habitat-seeking” behavior, when mites seek out a new oviposition site, was disrupted on both dead and oil-treated bees. “Questing” behavior, associated with mite transfer between hosts, increased on dead and oily bees. Both questing (F2,66 =7.88; P<0.001) and habitat-seeking (F2,66=21.28, P<0.001) behaviors were significantly different between all three treatments. Oil-treated bees gained protection from habitat-seeking mites because the normal behavior of the mites is interrupted. Questing behavior increased significantly on dead and oily bees, thus exposing the mites for a longer time and increasing the chances of desiccation.

In the decade since its introduction here, the lethal effects of this mite seem to diminish. To determine if this was a change in the lethality of mite populations, infested bees from several states were collected and the mites dissected. RAPDs was used to track possible shifts in genetic markers. Problems of reaction protocols, contamination and clean negative controls were mostly solved by using HPLC water that was not treated to UV light. PCR parameters where annealing temperatures ranged from 38-45C also produced good results. However, because of extremely low mite DNA concentrations, the results were inconclusive.  By testing a dilution series using one bee, it was found that as the concentration of DNA diminished to 0.038ng/ul, more bands in the gel appeared. RAPDs was not a good method of choice; this question still needs to be explored as future techniques are refined.

Last Modified: 10/21/2005
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