Managed honeybee population stocks are declining in many countries, worrying scientists, the public and
politicians. This decline affects us all, as it poses a risk to food security.
Honeybees can be
moved where needed and are not picky about the flower they visit to collect
pollen and nectar which they feed on. Thanks to these qualities, they are the
major crop pollinators relied on by humans. The honeybee equals and sometimes
surpasses all other wild pollinators for this task.
In the last
decade, many studies focused on honeybee health to identify the causes of
unusually high colony losses. Most of this work has been performed in Europe and North America where bees are exploited in large
scale commercial operations. Scientists observe interactions of many factors
affecting honeybee health.
But these
results are so far not sufficiently clear to understand the causes of the
declines and implement adapted mitigation measures. Scientists and beekeepers
will first need to understand the reasons for deaths amongst bees before they
can adjust their practices to ensure the stocks' survival.
Honeybee health
status or even basic data of population sizes in the wild before the modern
beekeeping area is unknown. We lack important information to evaluate the
severity of the current problem. Understanding how bees deal with pests,
pathogens and other environmental factors in Africa, where beekeeping has not
been as intrusive, could help scientists understand more about why the bees of
Europe and North America struggle.
How can African
honeybees help?
The honeybee, Apis mellifera, is also present in Africa.
In contrast to the docile European honeybees, African honeybees are more aggressive to
beekeepers and are rarely confined to man-made hives. The majority of their
estimated 310 million colonies strong population is wild and lives in natural
cavities in trees or ground.
A lack of data
on the health status of African honeybees has prompted several international
teams to investigate this issue in recent years. In attempting to deal with the
problem of colony losses, beekeepers and scientists throughout the world posed
the following questions:
1) Is it possible that by developing beekeeping to the current industrial
level, we pushed the honeybees to their biological limits? When managing these
pollinators, do we place them in such unnatural situations that they are
weakened?
2) Was the selective breeding used to improve desirable traits such as
honey production or docility done at the expense of their defence mechanisms?
3) Does the wide scale honeybee trade result in the spread of damaging
pathogens to which the honeybees are not adapted?
Increased knowledge
on African honeybee health
Recent health surveys indicated that honeybee populations in
South Africa, Uganda, Kenya and Benin are indeed healthy. Pathogens, either endemic
or imported, are present but do not at this time seem to generate unusual and
widespread mortality. A notable exception is the damage done by a certain honeybee. A particular honeybee lineage
originating in the Cape region in South Africa functions as a social parasite.
To promote its
own reproduction, this parasitic honeybee invades colonies of other subspecies
and exhausts their resources until they dwindle to death. Tens of thousands of
managed colonies in the hands of the beekeepers have been lost to this
parasite, while the wild populations still living in natural nests fortunately
seem spared. This means that beekeepers are seen as the vectors of the
parasitic bee as it largely affects managed honeybees.
This phenomenon
is one example of an unexpected and negative consequence of trade involving the
displacement of a subspecies of bees from their natural distribution range. The
huge numbers of bees being traded all over the word exposes them to numerous diseases.
In contrast, the
invasion by the most damaging honeybee parasite, the well named mite Varroa
destructor, does not show the same long term devastating effect on some African
honeybeepopulations.
Researchers are
very interested in identifying the tolerance mechanisms of the honeybee populations
able to survive infestation without treatments. Selective breeding of the
responsible behavioural or physiological traits could help the currently
susceptible populations survive in presence of the parasite. Control efforts of
the past decades have not resulted in parasite eradication and new methods are
required. Honeybees that can live in the presence of this mite without human
intervention are the Holy Grail for many scientists and beekeepers.
Learning from past mistakes
The African honeybee populations have so
far largely coped with the arrival of new parasites andpathogens. But measures should be put in place
to maintain their apparently healthy status. Beekeepers should work with local
honeybee populations and refrain from importing colonies from distant places.
Despite the
general positive situation, worrying signs of declining populations have
recently beenreported in
Madagascar, Kenya and South Africa. This is where colonies succumb to the newly
arrived varroa mite or where beekeepers have increasing difficulty trapping
wild swarms to build their stocks.
Africa would
benefit from the mistakes made elsewhere by preventing such problems through
the protection of honeybee populations. Before the states establish rules and
restrictions, better information for the primary stakeholders are needed.
Beekeepers play a vital role. They can help keep African honeybees healthy. The
African honeybee could be a major tool for researchers and beekeepers if they
want to learn about conserving the western honeybee.
No comments:
Post a Comment