Insect- Host Plant-Parasitoid Interactions : SORGHUM MIDGE Contarlnla sorghicola (Coqulllett) K GKausalyaauthorThree resistant (ICSV 745, ICSV 89058 and IS 10712) and three susceptible (Swarna, CSH 9 and ICSV 112) sorghum genotypes were sown on three dates each during the rainy (6, 15 and 30 Jul in rainy season 1992 and 2, 19 Jul and 6 Aug in rainy season 1993) and post-rainy (29 Oct, 13 Nov and 1 Dec 1992) seasons of 1992193. A modified headcage was developed for easy and precise collection of emerging insects. The species composition of natural enemies included three larval parasitoids (Aprostocetus sp., Eupelmus sp. and Apanfeles sp.) and one predator (Orius sp.). Parasitoid emergence commenced 1 - 3 weeks after initiation of midge emergence. The population dynamics of Aprostocetus sp, was similar in susceptible and resistant genotypes. Aprostocetus sp, activity was higher in the first and third sowing dates than in the second and greater numbers were recovered from susceptible than from resistant genotypes. The extent of parasitization of midge larvae did not follow a definite pattern with resistance or susceptibility of the host plant to midge. The lowest levels of parasitization were recorded from midge resistant ICSV 745. Studies on the tritrophic interactions indicated variations in preference for host stage for parasitization and development in rainy and post-rainy seasonsSorghum1994College of Agriculture, Rajendranagar;Department of EntomologyThesis