Varroa destructor is a parasitic mite that feeds 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 is a carrier for a virus that is particularly damaging to the bees.
Bees that were infected with this virus during their development will often have a visible "K-wing" deformity.
Varroa has led to the virtual elimination of feral bee colonies and is a major problem for kept bees.
Varroa was first discovered in Southeast Asia in about 1904, but has now spread virtually worldwide.
Varroa was discovered in the United States in 1987.
see also
Varroa Map
Varroa mites can be treated with commercially-available miticides.
Miticides must be applied strictly according to the label in order to minimize the risk of contamination of honey that might be consumed by humans.
Proper use of miticides will also help to slow the development of resistance among the mites.
Varroa mites can also be controlled through non-chemical means.
Most of these controls are intended to reduce the mite population to a managable level, not to eliminate the mites completely.
Varroa mites
Varroa mite on a honeybee larva
Several attempts have been made (and are continuing) to breed bees with an increased resistance to varroa mites.
In fact, the Africanized honeybee was originally an experiment to cross-breed mite resistance into the European honeybees common in the Americas.
Acarine mites
Acarapis woodi is a small parasitic mite that infests the airways of the honeybee. The first known infestation of the mites occurred in the British Isles in the Early 20th Century, and was regarded as having wiped out the entire bee population of the isles (later genetic studies have found remnants that did survive) and dealt a devastating blow to British beekeeping. Brother Adam at the Buckfast Abbey developed a resistant hybrid bee known as the Buckfast bee, which is now available worldwide to combat acarine disease.
Diagnosis for tracheal mites generally involves the dissection of a sample of bees from the hive.
Acarine mites, formerly known as tracheal mites are believed to have entered the US in 1984 via Mexico.
Acarine mites are commonly controlled with Menthol, either allowed to vaporize from crystal form or by feeding the bees grease patties mixed with menthol.
Bacillus larvae is a spore-forming bacterium.
This disease only affects the bee larvae but is highly infectious and deadly to bees. Infected larvae will darken and die. Lab testing is necessary for definitive diagnosis, but a good field test is to touch a dead larva with a toothpick or twig. It will will be sticky and ropey (draw out). Brood also has a characteristic odor, and experienced beekeepers with good smellers can often detect the disease upon opening a hive. In the photo at right, some larvae are healthy while others are diseased. Capped cells with decomposing larvae are sunken, as can be seen at lower right. Compare with healthy brood at: Brood_(honeybee).
Chemical treatment of American foulbrood is possible using oxytetracycline hydrochloride, but because of the persistence of the spores (which can survive up to 40 years), the most common treatment is the destruction of the colony and burning of all equipment.
Chemical treatment is sometimes used prophylactically, but this is a source of considerable controversy because the bacterium seems to be rapidly developing resistance.
European foulbrood is generally treated chemically with oxytetracycline hydrochloride.
Hives with Chalkbrood can generally be recovered by increasing the ventilation through the hive and/or by requeening the hive.
Nosema is treated by increasing the ventilation through the hive.
Some beekeepers will treat a hive with antibiotics.
Nosema can also be prevented or minimized by removing much of the honey from the beehive then feeding the bees on sugar water in the late fall. Sugar water made from refined sugar has essentially the same nutritional content as flower nectar but lower ash levels, decreasing the bees' risk of dysentery.
Aethina tumida is a small, dark-colored beetle that lives in beehives.
Originally from Africa, the first discovery of small hive beetles in the US occurred in Florida in 1987.
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A strong hive generally needs no treatment to control wax moths.
The bees themselves will kill and clean out the moth larvae and webs.
Wax moths are a significant challenge for beekeepers, though, because they can destroy the carefully built frames of empty comb that the beekeeper is saving for the next season.
Wax moths can be controlled chemically (the equivalent of moth balls) or by freezing the comb.
Because wax moths can not survive a cold winter, they are usually not a problem for beekeepers in the northern U.S. or Canada.
To minimize the risk of chilled brood, open the hive on warm days and at the hottest part of the day.
(This is also the time when the most field bees will be out foraging and the number of bees in the hive will be at its lowest.)
Learn to inspect your hive as quickly as possible and put frames with brood back where the bees can cluster on it immediately.
Pesticide losses may be relatively easy to identify (large and sudden numbers of dead bees in front of the hive) or quite difficult, especially if the loss results from a gradual accumulation of pesticide brought in by the foraging bees. Quick acting pesticides may deprive the hive of its foragers, dropping them in the field before they can return home.
Insecticides that are toxic to bees have label directions that protect the bees from poisoning as they forage. To comply with the label, applicators must know where and when bees forage in the application area, and the length of residual activity of the pesticide.
Some pesticide authorities recommend, and some jurisdictions require, that notice of spraying be sent to all known beekeepers in the area so that they can seal the entrances to their hives and keep the bees inside until the pesticide has had a chance to disperse. However, sealing honeybees from flight on hot days can also kill bees. Beekeeper notification does not comply with the label directions, nor does it offer any protection to bees, if the beekeeper cannot access them, nor to wild native bees or feral honeybees. Thus beekeeper notification as a normal proceedure does not really protect all the pollinators of the area, and is, in effect, a circumventing of the label requirements. Pesticide losses are a major factor in pollinator decline.
See also: Africanized bee, bee
American foulbrood
Field test for American FoulbroodEuropean foulbrood
Melissococcus pluton is a bacterial brood disease that infests the guts of bee larvae.
European foulbrood is generally considered to be less deadly than American foulbrood.
European foulbrood does not form spores, though it can overwinter on comb.Chalkbrood
Ascophaera apis is a fungal disease that causes infected bee larvae to appear white and 'chalky'.Nosema
Nosema apis is caused by a spore-forming protozoan that invades the intestinal tracts of adult bees.
Nosema is normally only a problem when the bees can not leave the hive to eliminate waste (for example, during an extended cold spell in winter or when the hives are enclosed in a wintering barn). When the bees are unable to void (cleansing flights), they can develop dysentery.Small hive beetle
Slimed by hive beetle larvae
Hives infested at this level
will drive out bee colonies.Wax moths
Galleria mellonella (greater wax moths) will not attack the bees directly, but feed on the wax used by the bees to build their honeycomb.
The destruction of the comb, though, will spill or contaminate stored honey and may kill bee larvae.Chilled brood
Chilled brood is not actually a disease but is usually a result of mistreatment of the bees by the beekeeper.
Brood must be kept warm at all times.
Nurse bees cluster over the brood to keep it at the right temperature.
When a beekeeper opens the hive (to inspect, remove honey, check the queen, or just because he/she is curious) and prevents the nurse bees from clustering on the frame for too long, the brood can become chilled, deforming or even killing some of the bees.Pesticide losses
Honeybees are susceptible to many of the chemicals used for agricultural spraying of other insects and pests.
Because the bees forage up to several miles from the hive, they may fly into areas actively being sprayed by farmers or they may collect pollen from 'contaminated' flowers.External links and references