The Role of Local Natural Enemies in Population Dynamics of Chilo partellus (Swinh.) (Pyralidae) Under Subsistence Farming Systems in Kenya

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Abstract
The present article is one of a series of papers in preparation in which an ecological approach to developing a sound biocontrol programme for cereal stem borers is proposed and outlined. The proposed approach involves detailed population estimation and analysis in relation to crop phenology to determine the role of local natural enemies, evaluation of biocontrol potential of promising biocontrol agents, developing mass rearing and release technology and monitoring the impact of the biocontrol programme. In the example used to illustrate the first step in such a programme, life table analysis of data from a 2-year study on Chilo partellus on maize and sorghum under subsistence agriculture in Western Kenya, showed local predators (and unidentified factors) to contribute up to 97.6% of generation mortality of the borer in the age interval from egg to early instar larva, while parasitoids and pathogens contributed less than 1% mortality in the various life stages. Hence, a programme involving conservation and augmentation of local predators and introduction of selected exotic parasitoids of this borer seems appropriate. This represents an attempt to apply life table analysis, taking into account plant phenology, in studying interacting populations under subsistence farming conditions.