Diseases of the honey bee
Varroa destructor and Varroa jacobsoni are parasitic mites that feed off the bodily fluids of adult, pupal and larval bees. Varroa mites can be seen with the naked eye as a small red or brown spot on the bee’s thorax. Varroa are carriers for a virus that is particularly damaging to the bees. Bees that are infected with this virus during their development will often have visibly deformed wings.
Varroa have led to the virtual elimination of feral bee colonies in many areas and is a major problem for kept bees in apiaries. Some feral populations are now recovering — it appears that they have been naturally selected for Varroa resistance (these so-called feral populations may be africanized bees).
Varroa were first discovered in Southeast Asia in about 1904, but has now spread virtually worldwide. Varroa were discovered in the United States in 1987, in New Zealand in 2000.
Varroa are generally not a problem for a hive that is growing strongly. When the hive population growth reduced in preparation for winter or due to poor late summer forage the mite population growth can overtake that of the bees and can then destroy the hive. Often a colony will simply abscond (leave as in a swarm, but leaving no population behind) under such conditions.
Varroa in combination with Deformed Wing Virus and bacteria have been theoretically implicated in Colony Collapse Disorder.
