Pests and Pest Control

African farmers generally face a tougher battle with pests than do farmers in temperate regions. The warm temperatures and abundant rainfall of the continent's tropical regions create an environment in which pests flourish. To make matters worse, chemical pesticides developed in Western nations are of limited use in Africa.

Insects and rodents do the most damage to African crops. Insects of all sizes consume up to 15 percent of African crops in the field, and they destroy between 10 and 50 percent more during storage, processing, and marketing. Swarms of locusts periodically descend on huge areas of land to devour the green parts of every type of plant. Termites and rats damage many stored foods. In addition, weeds and other parasitic plants harm crops as they grow by competing for food, water, and light. The chemical pesticides used in western nations have many drawbacks in Africa. These pesticides often are not effective against species found primarily in Africa. Also, the continent's high temperatures and heavy rains reduce the long-term strength of chemical pesticides. In any event, few African farmers can afford them.

For these reasons, African farmers rely heavily on a variety of physical, biological, and cultural pest control methods. Physical pest control methods include dragging brushes or tarred paper over crops to remove or crush insects and creating metal barriers to keep termites out of storage bins. Biological methods involve the use of living organisms to fight pests. For example, a type of American wasp has been imported to combat a pest that destroys cassava, an important staple crop in Africa. Cultural pest control includes practices such as rotating crops and planting different types of crops on the same land to control the spread of insect pests and weeds. Farmers also select crop varieties that show the greatest natural resistance to pests.

Several recent technological advances in pest control may help African farmers. Farmers may use packages that combine seeds with weed killers and fertilizers, or they may plant crops that are genetically engineered to be resistant to certain pests. However, since these technologies can be expensive, experts are also working to develop new practices that take advantage of indigenous farmers' knowledge and locally available tools and materials. (See also Agriculture, Plants: Varieties and Uses.)