varroa destructor

Varroa destructor is an external parasitic mite that attacks honey bees Apis cerana, Apis mellifera, Bombus pennsylvanicus, Palpada vinetorum and Phanaeus vindex. It can only replicate in a honeybee hive. It attaches at the body of the bee and weakens the bee by sucking haemolymph. In this process the mite may also spread RNA viral agents and bacteria to the bee. A significant mite investation of a hive will lead to a dead-out usually in the winter. The varroa mite has been the parasite with the most pronounced economic impact on the beekeeping industry.

Origin

Varroa jacobsoni was the first honeybee mite that was classified in 1904 in Indonesia on Apis cerana. When the Varroa mite started its worldwide expansion in the range of the Western honeybee, scientists assumed that it was one and the same species. Up until 2000, scientist did not positively identify Varroa destructor as a separate species. In 2005, we know that only the Korea and Japan/Thailand genotypes of Varroa destructor can reproduce in colonies of Apis mellifera (Western honeybee). Varroa jacobsoni is a fairly benign parasite of Apis cerana. This late identification led to some confusion and mislabeling in the scientific literature.

Anatomy

reddish-brown in color 1.00-1.77 mm long and 1.50-1.99 mm wide flat button shape
eight legs

Life Cycle

The female mite enters a honeybee brood cell. As soon as the cell is capped, the mite lays eggs. The young mites hatch in about the same time as the young bee develops and leave the cell with the host. The model for the population dynamics is that there is exponential growth when bee brood is available and exponential decline when no brood is available.

Reproduction

Mites reproduce on a 10-day cycle. In 12 weeks the number of mites in a Western honeybee hive can roughly multiply by 12. Russian honey bees are one third to one half less susceptible to mite reproduction. Source: Russian Queens Bee-little Mites' Impact by J. Raloff, Science News, Aug. 8, 1998