By Dylan Voeller and James Nieh
1. Africanized honeybee feeding on water
I.††††††††† Principles & concepts introduced in this exercise
††††††††††† A.††††††† What are Africanized honeybees?
††††††††††† B.††††††† What makes them dangerous?
††††††††††† C.††††††† Why are they so aggressive? Predation & evolution.
How did they come to the
Africanized honeybees are of the same species as the more
well known European honeybee, but belong to a different race or subspecies, meaning that they have similar characteristics
but come from different geographic regions. The two look nearly identical,
and can only be distinguished from one another by measuring differences
under a microscope and analyzing their DNA. The variation between these
two types of bees can be attributed mostly to differences in behavior
as affected by climate, predator abundance, and resource distribution.† European honeybees, as their name suggests,
evolved in areas of
Figure 2.† Aggression is not just limited to Africanized honeybees! Take a look at this stingless bee attacking an Africanized honeybee.† For more information, please take a look at the exercise on stingless bee aggression.
The constant pressure from a higher concentration of predators in the tropics has also affected the evolution of Africanized honeybees, making them more aggressive since they are constantly having to ward off hungry nest attackers.† Africanized honeybee venom is not more painful or voluminous than temperate honeybee venom, its just that many more bees will sting!† The threshold for stinging response in Africanized honeybees is much lower; only a minor disturbance such as a slight motion, vibration, or odor is needed. Africanized honeybees are very sensitive to alarm pheromone (the odors, smelling a bit like banana, which foragers release from their sting gland and glands located in the head when they are alarmed) and produce much more of it than European honeybees.† A study by Collins (1985) showed Africanized honeybees respond 2.4 times faster to alarm pheromone and about 30 times as fast to a moving target! Once Africanized bees have been stimulated, they are also much more likely to respond in group attacks. During such attacks they will sting anything in sight that is moving and may pursue a source of disturbance for up to a kilometer (Winston 1992).
biology of Africanized bees, including their higher level of aggressiveness,
is thought to play a role in their successful invasion of the
III.†††††† Discussion questions & exercises
B.†††††††† If you met an Africanized honeybee on a flower far away from its nest, would it be more dangerous than a normal honeybee?
C.†††††††† Aside from humans, what animals are bee predators?
D.††††††† Do bees have effective defenses against these predators?
Some websites offering further information on Africanized bees:
Collins, A.M., 1985. Africanized
Crane, E., 1990. Bees and beekeeping:
science, practice, and world resources.
Ratnieks, F., and Visscher, P.K., 1996. Sinaloan beekeepers adapt pollination to Africanized bees.
M.L., 1992. Killer bees: the Africanized
honey bee in the
V.††††††† Suggested Answers. Please see the for educators page for the answers to these questions and suggested discussion topics.