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The benefit of bees

Good pollen sources are requiredForget about honey, pollen and royal jelly. Just think of a world without beans, tomatoes, onions and carrots, not to mention the hundreds of other vegetables, oilseeds and fruits that are dependent upon bees for pollination. And the livestock that are dependent upon bee-pollinated forage plants, such as clover. No human activity or ingenuity could ever replace the work of bees and yet it is largely taken for granted. It is often not realized just how easy it is to help or hinder their effectiveness as crop pollinators nor how much is lost by their loss.

To United States agriculture alone, the annual value of honey bee pollination can be counted in billions of dollars. Bees pollinate about one-sixth of the world's flowering plant species and some 400 of its agricultural plants. Poorly pollinated plants produce fewer, often misshapen, fruits and lower yields of seed with inevitable consequences upon quality, availability and price of food. One of the few farm activities that can actually increase yields, rather than simply protect existing yields from losses, is to manage bees to encourage good pollination. The destructive effects of the varroa mite (See varroa - a 'mitey' pest of bees), loss of wild bee nesting habitat, low world honey prices, Africanization of bees (see box) and the use of pesticides are making conservation of wild bees more important than ever.

Africanization

African bees have a fearsome reputation as 'killer' bees. Far more aggressively defensive than European honey bees, their stinging attacks on people and animals have caused alarm as they have spread through the Americas. Imported into Brazil from South Africa in 1956, hybrid Africanized males escaped and have been outperforming local European bees in fertilizing queens ever since. Africanized bees can now be found from Argentina to Arizona and could soon reach California. But Africanized bees have their good points. They do better than European bees in tropical climates, they are less susceptible to some widely used insecticides and, most usefully, they are resistant to the varroa mite. Brazilian beekeepers have no need to spray against the mite and can sell their honey as pesticide-free. So can the good characteristics of each species be combined and the less good avoided? Research continues.

GM crops and bee pollination

One indication of their importance in crop production is the frequent reference to bees in the debate about GM crops. Are transgenic crops, particularly those engineered to carry insecticides, harmful to bees? Or, are they good for bees because their insecticidal properties, which are targeted only to specific pests, mean that the use of conventional, broad spectrum insecticides can be reduced?

The second issue is to what degree bees and other pollinators may carry transgenes - and here the concern is for those conferring herbicide tolerance - to wild, weedy species, thereby making them more difficult to control. The debate, and the research, continues.

Wild bees need long-lasting, undisturbed nesting sites in sunny, relatively bare patches of ground with a diversity of nectar and pollen-rich plants nearby. The greater the variety of flowering plants, the greater the number of bee species that will be attracted. One of the major risks, to both bee and plant diversity, is their separation through increasing fragmentation of wild uncultivated areas. Without bees, many flowering plants fail to set seed and without flowering plants, there is no food for bees. Leaving field margins, ditches, roadside verges and woodland edges unsprayed with chemicals, and undisturbed, does much for bee conservation.

By definition, chemical insecticides are harmful but individual products vary greatly in their toxicity to bees. Pesticides may kill quickly or, worse, kill slowly. If not immediately killed, bees can carry the contaminated pollen back to the colony where it enters the food chain and kills many more. An insecticide may be harmless to the health of the bees but may nevertheless inhibit pollination of the crop by acting as a repellent. Careful choice of pesticides may do much to reduce harm but farmers, especially in developing countries, may have few options and, on the whole, the more targeted the pesticide to the pest, the more expensive the product. Biological pesticides, however, are relatively safe to bees.

Timing of insecticide application is also critical. Many degrade after a few hours and spray applications in the late evening, when bees are inactive, reduces the risk that bees will be affected. Where bee keepers are hired by growers to bring hives to an orchard or field for pollination, crop protection must obviously be the subject of agreement between both parties, and never more so than where GM crops may be involved. (See box)

The use of bees for crop pollination is a huge subject (see In Print Crop Pollination by Bees). Different bee species behave differently and different crops have different pollination requirements. This is a tough time for farmers but it is also a tough time for beekeepers. Anything that can be done to enhance the pollination effectiveness of bees will be good for bees, beekeepers - and farmers.

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