From Science online, ecology news of the week, by Constance Holden:
"Honeybees (Apis mellifera) are in trouble, according to a report on North American pollinators unveiled this week by a committee of the National Research Council. The committee calls for better long-term monitoring of all pollinators, noting that few records exist for species other than honeybees." (Read more.)Honeybee decline in California, where important cash crops such as almonds are heavily dependent on honeybees for pollination, is largely due to viral diseases compounded by the presence of the ectoparasitic mite Varroa destructor. A search in Biological Abstracts on "varroa destructor and apis" yeilded 163 records, including this study implicating reproductive behavior as a mode of transmission:
Yue, Constanze; Schroeder, Marion; Bienefeld, Kaspar; Genersch, Elke. “Detection of viral sequences in semen of honeybees (Apis mellifera): Evidence for vertical transmission of viruses through drones.” Journal of Invertebrate Pathology, v. 92 issue 2, 2006, p. 105-108. [available on the OhioLINK Electronic Journal Center]
Read Thomas D. Seeley's Honeybee ecology for an excellent introduction to the subject.