The biology of Chilo partellus (Swinhoe) was studied on two resistant, IS 2205, IS 5469 and two susceptible, HC 136, ICSV1 sorghum genotypes. Significant differences were observed between resistant and susceptible genotypes in regards to larval mortality in whorl, larval period, larval weight, larval length, per cent pupation, pupal weight, fecundity per female and total life span of this pest. Growth index was also influenced by the resistant genotypes. It has been concluded that high mortality of larvae on resistant lines is due to antibiosis.

The correlations between the characters of the pest biology have been worked out and larval stage was the most important parameter influencing the total pest survival and population build-up in the succeeding generations.

Insect pests are major yield reducers in sorghum under traditional farming practices in Africa. The use of resistant varieties in an integrated pest management scheme provides the most cost effective and practical means of sorghum insect control. Corneous grain sorghums are more weevil resistant than their softer endosperm counterparts. A wide range of sources of resistance to shootfiy, stem-borer and greenbug are known. Breeding for resistance to sorghum insects has been practised with varying degrees of success. Greenbug resistance breeding in sorghum has been successful in the U.S.A. Stem-borers are perhaps the most serious group of sorghum insects in Eastern Africa and further efforts are needed in breeding for resistance to these pests. In an effective pest resistance breeding work, the breeder and the entomologist must work as a team to make the fastest possible progress. Where several pests are of concern in an area, genotypes with multiple resistance in good agronomic backgrounds are needed.

Lepidopterous stem-borers are the most serious and widely distributed insect pests of sorghum. Among the several avenues of their control, the use of resistant varieties holds good prospects. In order to identify the sources of resistance to stem-borers (Chilo partellus, Busseola fusca, Eldana saccharina and Sesamia calamistis), a large number of sorghum lines from Kenya, India and Texas, U.S.A. have been screened under a very heavy natural infestation in Western Kenya. Several promising lines with resistance potential have been identified for the stem-borer complex which include: IS 10370, L-2 (TX 2780), IS 10364, IS 1044, S-178, IS 3962, IS 4213, IS 12447, IS 18479, IS 18326, L-l (A&B TX 2756), IS 4405, IS 10711, IS 18676, IS 5613, IS 18517, IS 18323, IS 4881, IS 1151 and IS 18427.