The honeybee colony has an intricate social structure where different casts
play vital roles in its survival and procreation. This is further complicated by
task definitions of workers to provide forage and water; tend the brood, queen
and drones; defend the colony; maintain optimal humidity and temperature levels
in the nest; and building combs. Studying the biology of the honeybee and social
structure of the colony is crucial in optimizing the potential and worth it has
in and for agriculture and in developing new and better beekeeping methods.
The unique characteristic of the laying workers of the Cape honeybee (Apis
mellifera capensis) to produce females from unfertilized eggs was first
described in 1912. Initially this characteristic known as thelytokous
parthenogenesis was regarded as peculiar and scientifically interesting but not
of any real importance. This changed between 1977 to 1979 when some experimental
colonies taken from the Cape peninsula were placed in an African honeybee,
(Apis mellifera scutellata) apiary in the summer rainfall region. This
resulted in many African honeybee colonies being taken-over by laying workers of
the Cape honeybee which soon died out. A catastrophe was averted when all the
infested colonies in that apiary and in a radius of 3.5 km were killed to
prevent the problem from spreading to other beekeepers.
Beekeepers, through subsequent warnings, for many years thereafter refrained
from mixing the two sub-species. However, in 1991 capensis laying workers
were identified in honeybee colonies of commercial beekeepers in the summer
rainfall region. As the problem escalated, thousands of colonies died out. In an
effort to prevent the total destruction of all hived colonies in the region, the
South African government issued a proclamation that all infested colonies should
be killed. Compensation was paid to those commercial beekeepers who could prove
that they had complied with the law. Despite these strict measures the problem
persisted, and it is still the most serious one plaguing beekeeping outside the
geographical distribution area of the Cape honeybee.
Contact: For general information on Apis mellifera
capensisMr. Mike AllsoppE-Mail: firstname.lastname@example.orgCenter:
The only way to prevent Cape problem bees from killing colonies is to eliminate the problem before it starts.
Trapped swarms should be tested by beekeepers to confirm their purity. Only those that prove beyond doubt to be pure scutellata must be used for beekeeping.
Beekeepers should not place their colonies in the same areas as beekeepers that may have the Cape problem bees in their colonies.
Basic hygienic procedures should be followed when working with bees. The more colonies that are worked during a single day, the higher the chance of transferal of Cape problem bees between colonies.
Reduce movement of bees and brood frames between apiaries to the minimum. It has been demonstrated that not only can apiaries be kept capensis free, but also even if part of the population has been taken over, the problem can be contained to a single apiary.
Select colonies and start a breeding program by rearing queens and drones from the selected colonies. The breeding station should be as isolated and as free of wild swarms as possible to prevent 'unwanted' genetic material entering the breeding lines.
General good management practices such as keeping good records of queen replacement and colony performance will go a long way to curtail and eventually eliminate the problem.
Under natural conditions the queen mates once with drones and stores their
sperm in her spermatheca for as long as she lives. She regulates fertilsation of
the eggs as they pass from her ovarioles past her spermatheca. Those laid in
worker cells are fertilized (2n) while those laid in drone cells are not (n). If
a queen is removed from, or lost to a colony, some workers will develop into
laying workers. Because they were never mated they can not fertilize their eggs
and therefore lay only haploid (n) eggs that develop into drones. However the
Cape honeybee is unique in this regard because when laying workers develop they
can produce worker offspring as a result of a process called telytokous
Thelytoky is the term used to describe the development of diploid (2n) eggs
without fertilization, which in the case of honeybees can give rise to workers
or queens (females). This is the opposite of arrhenotoky where haploid (n) eggs
develop because no fertilization took place.
The outcome of thelytokous parthenogenesis is a new female genetically almost
identical to the worker that produced the egg. Therefore, the offspring of
capensis workers can be called pseudo-clones. Hence, once a Cape laying worker
has successfully reproducing in an A. m. scutellata colony its offspring
will have the same genes and are likely to be able to do exactly the same.
Eggs laid by workers of Apis mellifera capensis result from a normal
meiosis followed by a fusion of one pronucleus with the central nucleus to
regain diploidy. This process is called automixis.
It is uncertain why thelytoky has evolved in the A. m. capensis bee,
but it is generally believed that the environment (strong winds) and/or forage
(fynbos biome) are involved.
Soon after the report in 1996 that Capensis laying workers were widespread in
African honeybee colonies the Director-General of the National Department of
Agriculture appointed the so-called Capensis Working Group. This group was
tasked to study and solve the "capensis problem". Chemical control could not be
used against the capensis laying problem worker bees. Extensive research held
the only reasonable hope of solving the problem.
and parasite surveys
and parasite surveys
Many beekeepers assisted in the programme at their own expense and
contributions in kind were probably worth more than a million rand.
What follows is a synopsis of the research and results of the Capensis
Comprehensive surveys were launched to determine the extent of the problem.
The aims of the surveys were to map the distribution of the problem and
determine over time the impact (colony loss) the laying workers caused. Twenty
colonies per apiary of sedentary and migratory apiaries of small-scale as well
as commercial beekeeping operations were surveyed. The colonies were visually
inspected and worker bees were sampled three times (at 6 monthly intervals) over
a one and a half-year period. The collected bees were dissected to determine
ovariole numbers, spermatheca size and stage of egg development.
Capensis laying worker colonies were found throughout the
summer rainfall region in sedentary as well as migratory colonies. Although the
number of colonies that were taken over varied between apiaries, the severity of
the problem didn't. Most colonies that were taken over died out within a year.
Disease and parasite surveys:
To eliminate the possibility that colonies died of known
diseases rather then capensis take-over a survey of diseases and parasites was
done concurrently with the capensis survey. Hives were visually examined and
brood and workers collected and analyzed for the following important diseases:
European foulbrood, American foulbrood, Nosema, chalkbrood, Tracheal mites,
Varroa, viruses including sacbrood, and malpighamoeba.
Results:No disease was found that caused serious
colony deaths or that exhibited the same symptoms seen in capensis
To suppress the Capensis problem bees from taking over A. m.
scutellata colonies chemical signals (pheromones) emitted by A. m.
capensis queens to control capensis workers from becoming laying
workers while the queen was still present was studied. Such compounds could be
synthesized and introduced into colonies in affected regions to control the
Results:No pheromones have yet been isolated but the search is
To test whether the distance between the queen (in the brood
chamber) and the workers (in the top supers) had an effect on the development of
capensis laying worker development, two sets of colonies were compared.
In the one set two supers were added while four supers were added to the second
set. These two sets were similarly managed in all other aspects for a one-year
Results:The colonies with four supers were more
likely to be taken over than those with only two supers. It will, therefore, be
better to keep the colonies smaller and rather harvesting more often than
Results:Colonies moved more often were more like to
be taken over. Wheather it was the stress placed on the colonies or the
increased chances of drifting due to the increased manipulations and
re-orientation of bees moved to new areas was not ascertained. Another
interesting finding was that the beekeeper's profit margin was greater with
Not all infestations could be accounted for by drifting of workers between colonies or accidental introductions of workers or brood through normal colony manipulations. To determine whether the infestation was directed or non-directed, and whether residual remains of a queenless capensis-infested colony could give rise to a new capensis colony as a further source of infestation, was tested. These experiments were done in the natural capensis distribution area.
Setting up trap-hives in the Kruger National Park
Infested queenless colonies did abscond and even reared new queens from the eggs of laying workers. However, this was not seen with problem bees in the natural scutellata area. In the scutellata area the problem was proliferated by bees that had probably gained the ability to successfully infiltrate and rear brood in the presence of a healthy productive scutellata queen. This may have evolved through auto-selection between the laying workers and unnatural selection as a result of so many colonies being killed by beekeepers.
No capensis laying workers could establish in the wild population where they were not subjected to human interference.
DNA studies further strengthened this theory as it proved that the problem bees were genetically very similar.
Laying worker eggs in a queen cell cup
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