Traditional African plant products to protect stored cowpeas against insect damage : the battle against the beetle

Seeds of the cowpea plant, Vigna unguiculata , a tropical crop, are very susceptible to attack by the cowpea beetle. This specialist beetle needs only the beans to reproduce rapidly.

Most farmers in West Africa have few possibilities to treat the beans and they face their stored supply, on which they are dependent for their daily nourishment, be destroyed within a few months. From lack of other measures, these farmers traditionally used plants, stored together with the beans for protection. In the laboratory, such plants have been tested as powders and as extract for their effect against the beetle. Side effects on natural enemies of the beetle have also been tested for and in a review of the literature, effects on humans have been investigated. Together with the results from a field test in Africa, this gives a picture of the potency of local means to protect stored seeds against insects.