The popular term ‘Killer bee’ has only limited scientific meaning today because there is no generally accepted fraction of genetic contribution used to establish a cut-off.
While the native African bees are smaller, and build smaller comb cells than the European bee, their hybrids are not smaller.
They do have slightly shorter wings, which can be reliably recognized only by performing a statistical analysis on micro-measurements of a substantial sample.
One problem with this test is that there is also an Egyptian bee, present in the south eastern United States, that has the same morphology.
Currently testing techniques have moved away from external measurements to DNA analysis, but this means the test can only be done by a sophisticated laboratory.
Molecular diagnostics using the mitochondrial DNA (mtDNA) cytochrome b gene can differentiate A. m. scutellata from other A. mellifera lineages, though mtDNA only allows one to detect an Africanised colony that has an Africanised queen, and not colonies where a European queen has mated with Africanised drones.
There are two lineages of African bees in the Americas: actual matrilinial descendants of the original escaped queens and a much smaller number that are African through hybridization. The matrilinial descendants carry African mtDNA, but partially European nuclear DNA, while the bees that are African through hybridization carry European mtDNA, and partially African nuclear DNA. The matrilinial descendants are in the vast majority.
This is supported by DNA analyses performed on the bees as they spread northwards; those that were at the “vanguard” were over 90% African mtDNA, indicating an unbroken matriline (Smith et al., 1989), but after several years in residence in an area interbreeding with the local European strains, as in Brazil, the overall representation of African mtDNA drops to some degree. However, these latter hybrid lines (with European mtDNA) do not appear to propagate themselves well or persist.
Population genetics analysis of Africanised honey bees in the United States, using a materially inherited genetic marker, found 12 distinct mitotypes, and the amount of genetic variation observed supports the idea that there has been multiple introductions of AHB into the United States.
Consequences of selection:
The chief difference between the European races or subspecies of bees kept by American beekeepers and the African stock is attributable to selective breeding.
The most common race used in North America today is the Italian bee, Apis mellifera ligustica, which has been used for several thousand years in some parts of the world and in the Americas since the arrival of the early European colonists. Beekeepers have tended to eliminate the fierce strains, and the entire race of bees has thus been gentled by selective breeding.
In central and southern Africa, bees have had to defend themselves against other aggressive insects, as well as honey badgers, an animal that also will destroy hives if the bees are not sufficiently defensive. In addition, there was formerly no tradition of beekeeping, only bee robbing.
When one wanted honey, one would seek out a bee tree and kill the colony, or at least steal its honey. The colony most likely to survive either animal or human attacks was the fiercest one.
These hardy bees had to adapt to the hostile environment of sub-saharan Africa—surviving prolonged droughts and fighting for nectar. Thus the African bee has been naturally selected for ferocity.
Defensiveness:
African bees are characterized by greater defensiveness in established hives than European honey bees. They are more likely to attack a perceived threat and, when they do so, attack relentlessly in larger numbers. Also, they have been known to pursue their threat for over a mile.
This aggressively protective behaviour has been termed by scientists as hyper-defensive behavior. This defensiveness has earned them the nickname “killer bees,” the aptness of which is debated. Over the decades, several deaths in the Americas have been attributed to African bees.
The venom of an African bee is no more potent than that of a European honey bee, but since the former tends to sting in greater numbers, the number of deaths from them are greater than from the European honey bee.
However, allergic reaction to bee venom from any bee can kill a person, and it is difficult to estimate how many more people have died due to the presence of African bees. Most human incidents with African bees occur within two or three years of the bees’ arrival and then subside.
Beekeepers can greatly reduce this problem by culling the queens of aggressive strains and breeding gentler stock. Beekeepers keep A. m. scutellata in South Africa using common beekeeping practices without excessive problems.
Fear factor:
The African bee is widely feared by the public, a reaction that has been amplified by sensationalist movies (such as The Swarm and The Deadly Bees) and some of the media reports. Stings from African bees kill 1–2 people per year in the United States. As the bee spreads through Florida, a densely populated state, officials worry that public fear may force misguided efforts to combat them.
“ News reports of mass stinging attacks will promote concern and in some cases panic and anxiety, and cause citizens to demand responsible agencies and organizations to take action to help ensure their safety. We anticipate increased pressure from the public to ban beekeeping in urban and suburban areas. This action would be counter-productive.
Beekeepers maintaining managed colonies of domestic European bees are our best defence against an area becoming saturated with AHB. These managed bees are filling an ecological niche that would soon be occupied by less desirable colonies if it were vacant. ”
Florida African Bee Action Plan:
The much smaller and much more aggressive South American stingless bee Trigona spinipes does not interbreed and is known to kill or chase Africanised bees.
Misconceptions:
The sting of the Africanised Honey Bee is no more potent than a garden variety honey bee, and they have a similar appearance. What makes Africanised honey bees more dangerous is that they are more easily provoked, quick to swarm, attack in greater numbers, and pursue their victims for greater distances.
An Africanised bee colony can remain agitated longer and may attack up to a quarter of a mile away from the hive.
Queen management in African bee areas:
In Mexico, where African bees are well established, pollination beekeepers have found that a purchased and pre-bred non-African queen may be used to locally create a first generation of virgin queens that are then bred in an uncontrolled fashion with the local wild African drones.
These first generation African queens produce worker bees that are manageable, not exhibiting the intense and massive defence reactions of subsequent generations. This offers a relatively economical method of safe local beekeeping conditions that would otherwise quickly lead to hazardous conditions.
Impact on existing apiculture:
In areas of suitable temperate climate, the survival traits of African queens and colonies outperform western honey bee colonies. This competitive edge leads to the dominance of African traits. In Brazil, the African hybrids are known as Assassin Bees, for their habit of taking over an existing hive of European bees; this habit is most evident when the hive being attacked has a weakened queen, so not all hives are equally vulnerable, and overall rates of hive usurpation can reach 20%.
Gentle African bees:
Not all African hives show overly defensive behaviour; some colonies are quiet, which gives a beginning point for beekeepers to breed a gentler stock. This has been done in Brazil, where bee incidents are much less common than they were during the first wave of the African bees’ colonization. Now that the African bee has been “re-domesticated”, it is considered the bee of choice for beekeeping in Brazil.
Information Sourced From:
