By Mike Schmolke
Gardeners are observant and study what they grow.
They should also be aware of the honey bees that visit the flowers on their plants – an essential part of a garden’s ecosystem. The bees collect pollen as it contains nutrients such as proteins, vitamins, fats, and minerals which are not found in nectar – a sugar solution secreted by the plants to attract the bees. As the bees move around on the flowers, pollen grains stick to the branched hairs on their bodies and get redistributed onto the stigmas of other flowers. The male element in the pollen grain moves down to the ovary of the flower and unites with the female element in the egg (ova). The egg is thus fertilised and grows into a seed.
Many different kinds of bees visit flowers to collect pollen and nectar for food for themselves and for their young. Bees all have hairs on their bodies to pick up the pollen grains. Most bees live solitary lives and do not form colonies like honey bees do. Carpenter Bees are solitary bees, and bore holes in timber where they rear their young on pollen and nectar. Some Carpenter Bees are quite large and are often referred to as Bumble Bees, but these do not occur in Zimbabwe.
Other bees are social bees. One of the lesser known types of social bee is the Trigona, or Stingless Bee, which lives in colonies. These small bees are sometimes called Mopani Flies. There are a number of different species of Trigonas in Zimbabwe with most of them occurring in the warmer areas. Some do, however, occur in Harare and they sometimes take up residence in the trap-hives that beekeepers build to attract honey bee swarms. Their combs are built horizontally – not vertically like honeybee combs. The brood combs are insulated with thin layers of wax while round pots of wax are built in a random fashion outside the brood nest. The pots are filled with honey and pollen to be eaten during the off-season.
All flowers have to be pollinated one way or another, and different agents are involved: bees, butterflies, birds, bats, wind – to name a few. Where extensive areas are ploughed up for crops the living pollinating agents can be displaced or destroyed altogether. The crop growers then need to bring in a pollinating agent. Strawberries, raspberries, blueberries, macadamia nuts, and almonds are but a very few of such crops.
Because honey bees can be kept in large colonies in bee hives they are used extensively for pollinating crops worldwide. In California, where almonds are grown on a large scale, beekeepers are paid to bring in about 1,400,000 hives of honeybees when the trees are in flower. Macadamia nut trees are now being grown extensively in Zimbabwe, Mozambique, and South Africa, and these countries too will need many colonies of honeybees for pollination.
Unfortunately, honeybees are often subjected to unfavourable conditions. Neonecotinicides are a family of insecticides that affect bees severely when they pick up traces of it from flowers that they visit. It causes them to become disoriented and they cannot get back to their hives. It results in Colony Collapse Disorder. These insecticides have now been banned or their use now severely restricted. Another problem is caused by Varroa mites, which previously occurred only in colonies of the honeybees in the Far East (Apos ceraua). The mites have now been spread by beekeepers and scientists who moved these bees into areas previously occupied by our types of honeybees Apir mellifora. The mites are of the tick family and suck the blood (haemolymph) of adult bees and also the blood of the larvai and pupae when they breed and multiply in the brood cells. The mites have affected the European races of A. mellifora severely and colony losses are high.
Varroa mites arrived in Zimbabwe a few years ago but our races (A.m. scutellata and M.m littorea) seem to cope with the mites and no losses of colonies have been recorded here. In a recent study it was found that some of our colonies somehow remove the mites’ legs. It should be possible to selectively breed bees that disable most of the mites which invade their colonies. Because of misuse of chemicals which kill the Varroa mites but not the bees, Varroa mites have become resistant to the chemicals. The use of chemicals is not now encouraged, also because traces can be found in honey and beeswax.
Beekeepers may keep bees in Harare and formal approval is not required. However, the bees will have to be removed if they annoy or disturb neighbours or other people, livestock, or pets. Beekeepers need to learn how to manage their hives properly and should attend courses or demonstrations or, at least, consult experienced beekeepers.