Friday, December 9, 2011

How Do Africanized Honeybees Take Over Domestic and Native Honeybee Populations?

We are often asked by people how Africanized Honeybees (AHBs) have moved into Arizona so quickly and taken over our native wild bee populations so effectively. We as professional commercial beekeepers and bee removal specialists have perspective on this from direct experience with our own commercial hives derived from experimentation, observation and applying beekeeping practices. This article will attempt to summarize our experiences in how African honeybees are so successful in environmental domination over resident bee species.
First, for purposes of clarification, honeybees are not originally native to Arizona. Although Arizona is bio-diverse in native pollinators and plant specific pollinators, the first recorded introduction of honeybees to our area originated with the Spanish missionaries. During their mission building period in the late 1500s and 1600s, honeybees were introduced to provide honey to sweeten sacramental wine. The species they introduced were Italian honeybees, (apis mellifera lingustica) which are known to be better adapted to hot climates than other species of European honeybees (EHBs). As a natural result of periodic bee swarming, swarms were cast into the local environment and developed into a population of native honeybees that was existent before the arrival of Africanized honeybees.
Second, the term “Africanized honeybees” may be a misnomer; it would suggest some degree of hybridization between native bee populations and the pure African honeybee strain (apis mellifera scutellata) that was originally brought to Brazil from Tanzania and has spread so quickly through South America and into North America. This is a controversial area and still the subject to much discussion, but from our experience, we claim African honeybees, widely known as “killer bees”, are genetically dominant and when they absorb a native honeybee colony, that colony is quickly converted and demonstrates all the characteristics of a pure African honeybee colony.
So, given these observations, how do African honeybees spread so quickly, dominate any given area and absorb local native honeybee populations? There are three methods we have observed.
1.      Dominance by frequent swarming.

Whereas European honeybees swarm once or twice a year under optimal environmental conditions, African honeybees swarm much more frequently. European honeybees will occupy and literally “farm” a specific area and will produce large amounts of honeycomb. Large amounts of stored honey help European honeybees to survive through extended periods of freezing cold in the winter months and survive in higher elevations. In contrast, African honeybees will produce less honey; devote much of their honey stores into brood development and, as a result do not do as well in periods of extended freezing cold or in higher elevations. Their survival strategy is propagation and expansion, much more than occupation of a specific area. If food sources are used up or depleted in a specific area of colonization, it is not uncommon for the entire colony to abandon the area and abscond.

Swarming is the process whereby honeybees will periodically sub-divide and send out a group of bees to find and establish a new home somewhere else. Usually, about 60% of the worker bees and the old queen bee are pushed out of the hive by the newly developed queen bee. The old queen carries the genetic characteristics of her ancestors and, in my opinion, the experiential knowledge of her lineage with it.

African honeybees frequently swarm and expand; it is their strategy for survival and the propagation of their species. In the desert southwest, if forage is depleted and water is scarce, as in drought periods, frequent swarming and absconding behaviors increase the African honeybees’ chance of survival.

2.  Dominance by fertilization.

Newly emerged queen bees will leave the colony to go out on a “mating flight” before they return their colony to become the primary egg layer and before the old queen is superseded (replaced) or leaves in a swarm. Whenever queens are cast, male bees (drones) are cast in advance and are available for fertilization. During the queen bees mating flight, she may be fertilized by as many as six drone bees and that will last her for life, usually from four to six years.  African queen bees emerge several days before European queen bees. African drone bees are produced in much larger numbers than in European honeybee colonies. As a result, cast European queen bees have a higher probability of being fertilized by African drone bees. Since African honeybee genes are dominate, a European honeybee colony can be converted by fertilization with African drones. Conversely, an African queen bee, because of genetic dominance, will not be affected by mating with a European drone bee.

 3. Dominance by usurpation.

Usurpation is a process whereby African honeybees will seek out and absorb a native honeybee  hive in their local area. In Tanzania, they were commonly referred to as “assassin bees.”  Typically, an African queen bee and five to fifteen worker bees will be sent out for the specific purpose of taking over a local native bee hive. This group of assassins will carefully land and  group under the entrance to the native beehive and wait until they adjust their pheromone   scent content to that of the native bee colony. Once accomplished, without disturbing the guard   bees, they enter the hive and kill the resident queen bee, her developing queen larvae and take over the process of laying eggs. Within four to six weeks, the approximate life span of a worker  bee, the colony, hive, will be converted and completely absorbed.
We can’t really argue with scientists on whether or not African honeybees hybridize or eventually can be domesticated by using beekeeping practices like periodic replacement of African queen bees with Italian queen bees. However, we do know we’ve tried it. We seriously doubt that any of these efforts will affect our wild, native honeybee population in Arizona for all of the reasons listed above. We know, from our experience as professional commercial beekeepers and bee removal specialists that Africanized honeybees, “killer bees,” have the potential of being very dangerous to humans, livestock and pets. It is common to hear someone report to us that they don’t believe their bees are Africanized because they have not been aggressive. We work with African honeybees. They are not always aggressive. The point is that they can be aggressive and extremely defensive depending on how long their colony has had a chance to develop and how they perceive they are being threatened. Our advice is to not take the chance. If you have a honeybee colony on your property or in proximity, have it checked out by a licensed bee removal specialist company, hopefully experienced in beekeeping, and find out. There have been too many stinging injuries and deaths in Arizona, and other southwestern states, to assume otherwise.