Bioecological studies on Dentichasmias busseolae Heinrich and its potential for biological control of Chilo partellus Swinhoe

Abstract

Studies were carried out at Mbita Point Field Station, South Nyanza, western Kenya from 1984 to 1987 to determine the role of Dentichasmias busseolae Heinrich in the population dynamics of Chilo partellus Swinhoe and its potential as a biological control agent against the stem borer. D. busseolae is a solitary endoparasitoid which parasitizes and completes its development in the pupa of C. partellus. The developmental period ranged from 64.5 ± 9.5 days at 15°C to 12.0 ± 1.5 days at 30°C for males, and from 66.7 ± 9.8 days to 13.1 ± 2.1 days for females, respectively.The intrinsic rate of natural increase of the parasitoid was 0.1375, and the population multiplied 24.21 times in the mean generation time of 28 days. The functional response was curvilinear.Field parasitism in maize and sorghum was evident 7 weeks after plant emergence (APE). Thereafter, parasitism was persistent until crop harvest. The range of parasitism was 0 to 45.5% (x = 23.3%) on maize and 9.7 to 90% ( X = 36.0%) on sorghum respectively. Using laboratory and field observations, a model for the host searching process of D. busseolae has been constructed. The potential of the parasitoid in biological control programmes of C. partellus is also discussed.