Africanised honey bees, known colloquially as “killer bees”, are hybrids of the African honey bee, A. m. scutellata, with various European honey bees such as the Italian bee A. m. ligustica and A. m. iberiensis. These bees are far more aggressive than the European subspecies.
Small swarms of Africanised bees are capable of taking over European honey bee hives by invading the hive and establishing their own queen after killing the European queen.
History:
The Africanised honey bees in the Western Hemisphere are descended from 26 Tanzanian queen bees (A. m. scutellata) accidentally released by a replacement bee-keeper in 1957 near Rio Claro, São Paulo, in the southeast of Brazil, from hives operated by biologist Warwick E. Kerr, who had interbred honey bees from Europe and southern Africa.
Hives containing these particular queens were noted to be especially defensive. Kerr was attempting to breed a strain of bees that would produce more honey and be better adapted to tropical conditions (i.e., more productive) than the European bees used in South America and southern North America.
The hives the bees were released from had special excluder grates to prevent the larger queen bees and drones from getting out and mating with local (non-African) queens and drones.
However, following the accidental release, the African queens and drones mated with local queens and drones, and their descendants have since spread throughout the Americas.
The African hybrid bees have become the preferred types of bee for beekeeping in Central America and in tropical areas of South America because of improved productivity. However, in most areas the African hybrid is initially feared because it tends to retain certain behavioural traits from its African ancestors that make it less desirable for domestic beekeeping.
Specifically (as compared with the European bee types), the African bee:
- Is more likely to migrate as part of a seasonal response to lowered food supply.
- Is more likely to “abscond”—the entire colony leaves the hive and relocates—in response to stress.
- Has greater defensiveness when in a resting swarm, compared to other honey bee types.
- Lives more often in ground cavities than the European types.
- Guards the hive aggressively, with a larger alarm zone around the hive.
- Has a higher proportion of “guard” bees within the hive.
- Deploys in greater numbers for defence and pursues perceived threats over much longer distances from the hive.
- Cannot survive extended periods of forage deprivation, preventing introduction into areas with harsh winters or extremely dry late summers.
Geographic spread:
Map showing the spread of Africanised honey bees in the United States from 1990 to 2003 As of 2002, the Africanised honeybees had spread from Brazil south to northern Argentina and north to Central America, Trinidad (West Indies), Mexico, Texas, Arizona, New Mexico, Florida, and southern California.
Their expansion stopped for a time at eastern Texas, possibly due to the large number of European-bee beekeepers in the area. However, discoveries of the bees in southern Louisiana indicate this species of bee has penetrated this barrier, or has come as a swarm aboard a ship. In June 2005, it was discovered that the bees had penetrated the border of Texas and had spread into southwest Arkansas.
On September 11, 2007, Commissioner Bob Odom of the Department of Agriculture and Forestry said that Africanised honey bees established themselves in the New Orleans area. In February 2009, Africanised honeybees were found in southern Utah.
In October 2010, a 73-year-old man was killed by a swarm of Africanised honey bees while clearing brush on his south Georgia property, as determined by Georgia’s Department of Agriculture. It is the first time state officials have recorded that such bees exist in Georgia.
In tropical climates they compete effectively against European bees and, at their peak rate of expansion, they spread north at a rate of almost two kilometres (about one mile) a day. There were discussions about slowing the spread by placing large numbers of docile European-strain hives in strategic locations, particularly at the Isthmus of Panama, but various national and international agricultural departments were unable to prevent the bees’ expansion.
Current knowledge of the genetics of these bees suggests that such a strategy, had it been attempted, would not have been successful. As the Africanised honeybee migrates further north, colonies are interbreeding with European honeybees.
There are now relatively stable geographic zones in which either African bees dominate, a mix of African and European bees is present, or only non-African bees are found (as in southern South America or northern North America).
African honeybees abscond (abandon the hive and any food store to start over in a new location) more readily than European honeybees. This is not necessarily a severe loss in tropical climates where plants bloom all year but in more temperate climates it can leave the colony with insufficient stores to survive the winter.
Thus Africanised bees are expected to be a hazard mostly in the Southern States of the United States, reaching as far north as the Chesapeake Bay in the east. The cold-weather limits of the African bee have driven some professional bee breeders from Southern California into the harsher wintering locales of the northern Sierra Nevada and southern Cascade Range.
This is a more difficult area to prepare bees for early pollination placement in, such as is required for the production of almonds. The reduced available winter forage in northern California means that bees must be fed for early spring build-up.
The arrival of African honeybees in Central America is a threat to the ancient art of keeping stingless bees in log gums even though they do not interbreed or directly compete with the stingless bees.
The honey productivity of the African bees so far exceeds the productivity of the native stingless bees that economic pressures force beekeepers to switch. African honeybees are considered an invasive species in many regions.
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