Varroa destructor
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 Varroa destructor, Photo by Scott Bauer | ||||||||||||||
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Varroa destructor is an external parasitic mite that attacks honey bees Apis cerana and Apis mellifera, the bumblebee Bombus pennsylvanicus, the scarab beetle Palpada vinetorum and the flower-fly Phanaeus vindex. It was until recently mislabeled as Varroa jacobsoni.
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 infestation will lead to the death of a honeybee colony, usually in the winter. The varroa mite has been the parasite with the most pronounced economic impact on the beekeeping industry.
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Origin
Varroa destructor was until recently thought to be a closely related mite species called Varroa jacobsoni. Both species parasitize the Asian honey bee, Apis cerana. The mite species originally described as V. jacobsoni by Oudemans in 1904 is part of the same species complex, but not the same species that made the jump to Apis mellifera. That jump probably first took place in the Philippines in the early 1960’s. Only after Apis mellifera were imported to the Philippines, it came into close contact with Apis cerana. Varroa as a parasite of Apis cerana, also became a parasite of Apis mellifera. Up until 2000, scientists did not positively identify Varroa destructor as a separate species. In 2005, we know that the only varroa mites that can reproduce in colonies of Apis mellifera (Western honeybee) are the Korea and Japan/Thailand genotypes of Varroa destructor. Varroa jacobsoni is a fairly benign parasite of Apis cerana. This late identification in 2000 by Anderson and Trueman 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 (http://www.sciencenews.org/pages/sn_arc98/8_8_98/fob1.htm) by J. Raloff, Science News, Aug. 8, 1998
Worldwide Range Expansion
Control methods in beehive
- pyrethroid insecticide (Apistan)
- organophosphate insecticide (Coumaphos(Check-mite))
- oxalic acid trickling method or applied as vapor
- formic acid as vapor or pads
- Screened bottom board with sticky board is a purely physical method. It separates mites that fall through the screen and the sticky board prevents them from crawling back up.
- Foodgrade mineral oil as vapor and in direct application on paper or cords.
- Essential oil especially lemon, mint, and thyme oil
- freezing or heating of capped drone brood method
- swarming or queen arrest method. When the brood cycle is interrupted the mites cannot multiply either.
See also
- Notes on Varroa destructor (Acari: Varroidae) parasitic on honeybees in New Zealand (http://www.nhm.ac.uk/hosted_sites/acarology/saas/saasp/pdf10/saasp05b.pdf) ZHI-QIANG ZHANG, Systematic & Applied Acarology Special Publications (2000) 5, 9-14
- Managing varroa (http://www.csl.gov.uk/science/organ/environ/bee/factsheets/managing_varroa.pdf) Ministry of Agriculture, Fisheries and Food, 1996
- Varroa destructor: Revolution in the Making (http://www.ent.uga.edu/bees/Disorders/guest.htm) Keith S. Delaplane, University of Georgia; Bee World; 2001; 82(4): 157-159
- Tracheal and Varroa Mite Controls (http://www.agf.gov.bc.ca/apiculture/factsheets/221_varroa.htm) Apiculture Factsheet #221, Ministry of Agriculture, Food and Fisheries, Government of British Columbia; April 2004
- Essential Oils for Varroa Control (http://www.honeycouncil.ca/users/folder.asp?FolderID=1157|) Botanicals For Mite Control, Canadian Honey Council, 3/16/2003
