Studies on Population densities and some aspects of Control of the common Maize Stalkborer Chilo partellus Swinhoe, C. Orichalcocililla Strand. and Sesamia calamistis Hmps

Abstract

The population densities of the three coastal maize stalkborers, Chilo partellus Swin. C. orichalcoiliella Strand. and Sesamia calamistis Hmps. were estimated during the long rains of 1979, 1980 and 1981, showed the occurrence of two population peaks of different magnitudes during the years studied. There was an interchange in the pest status by the two Chilo species in different years during the experimental seasons. S. calamistis was found to be less important than the Chilo species, but became important during the reproductive stages of the maize crop particularly in the coastal hinterlands, e.g., Taita/Taveta District. Attempts made to screen in the field a number of insecticides applied in the funnels of maize plants to control the stalkborers showed that Thiodan and Dipterex granules applied at the rate of 12.0 kg/ha. and 4.4. kg/ha., respectively, were superior to other insecticides tested. The method of evaluating insecticidal performance was based on damage symptoms on leaves. Tests carried on resistance/susceptibility of maize varieties grown at the Coast showed that the backcrosses of the coast composite variety with '405' variety were less susceptible than other materials tested, indicating that the '405' variety contained resistance values since its partner was very susceptible to infestation by the stalkborers