Scanning Electron Microscopy of Female Varroa jacobsoni (Arthropoda: Acarina), Ectoparasite of the Honeybee Apis mellifera

The mite Varroa jacobsoni, an important ectoparasite of the European honey bee, was first recorded from the United States in 1987. In the present study, adult females were collected from infested Apis mellifera in Wisconsin during autumn and winter of 1987-88 and were examined by SEM. Bee colonies were infested heavily; up to 6 mites per host were recorded. Adult female mites were flattened and had a dome-shaped dorsal shield. The flat ventral surface was composed of a series of plates. A unique respiratory structure was found, as well as four different types of setae. Legs of this mite appeared to be modified for ectoparasitism and each was tipped by one of two types of distal empodia. Mouthparts appeared to be well modified for its diet of bee hemolymph, and apparently these are unique to this species. Although V. jacobsoni appears to posses numerous modfications for parasitism, it has yet to establish a relationship with Apis mellifera that is as close as with the Asian bee, A. cerana, in that V. jacobsoni continues to have a devastating effect on A. mellifera.