SPECIES RANGE AND ABUNDANCE OF INSECT PREDATORS OF THE BEAN APHID, APHIS-FABAE SCOP (HOMOPTERA, APHIDIDAE) ON COMMON BEANS IN KENYA

The diversity and abundance of insect predators of the bean aphid, Aph is fabae Scop. (Homoptera: Aphididae) on common beans, Phaseolus vulga ris L., were evaluated in Central Kenya. Predators included species in the Orders Coleoptera, Diptera, Hemiptera and Neuroptera. Coccinellid ae were the most abundant and diverse group and several species, such as Hippodamia variegata Goeze and Platynaspis capicola Crotch, had hit herto not been recorded on common beans in Kenya. Higher numbers of pr edators developed on beans during the short rains (up to 540/100 m2 pl ot) as compared to the long rain season (182/plot) of 1985. In both se asons, numbers of coccinellid larvae were high after the fourth week o f bean growth. The study provides evidence of an important build-up of insect predators on beans.