REDUCTION OF INSECT PEST ATTACK ON SORGHUM AND COWPEA BY INTERCROPPING

Two experiments to establish the relationship between insect suppressi on by intercropping and grain yield in sorghum and cowpea were conduct ed under held conditions. Treatments consisted of monocrops and interc rops of sorghum and cowpea and an additional pair of monocultures and mixtures protected by insecticides. Intercropping reduced the numbers of stem borer, Chile partellus in sorghum and thrips, Megalurothrips, sjostedti in cowpea. In the monocropped, unprotected sorghum, yield wa s reduced by 28% compared to the protected monocrop, while reduction i n the unprotected intercropped sorghum was 15% compared to the protect ed intercrop. Similarly, in the unprotected cowpea, monocrop yield was reduced by 94% and intercrop yield was reduced by 51%. Thus, there ar e yield advantages under conditions where intercropping reduces insect pest density. Intercropping can form a component of an integrated pes t management programme.