Chemical control of cereal stem-borers

Abstract

There are several stem-borer species recorded on important cereals such as rice, maize and sorghum as well as on grain legumes like cowpea. Those of considerable economic importance are: Chilo partellus, Sesamia infer ens, Sesamia eretica, Busseola fusca and Eldana saccharina on maize and sorghum; Sesamia infer ens. Chilo spp., Maliarpha separatella and Tryporyza incertulas on rice; and Maruca testu-lalis on cowpea. Chemical control of insect pests will continue to be a major component of integrated pest management. However, control of tissue borers with insecticides is relatively more difficult than control of the insect pests feeding externally on foliage, shoots and stems. The foliar application of dust and spray formulation of most of the available insecticides has generally proved to be unsatisfactory as these cannot penetrate deep inside the tissues in sufficient quantities to kill the borers. The recent advances in pest control technology, placing greater emphasis on use of various pest management components as well as insecticide selectively based on improved application methods has now made the control of stem-borers more effective and economical. Advantage can now be taken of the knowledge of the specific habits of the pests, period of peak activity of the most vulnerable stage and the economic thresholds for determining the appropriate time of application to control these pests. The development of new systemic insecticides and their granular formulation has further contributed towards the effective control of these borers. The recent research findings and recommendations for the control of cereal stem-borers are reviewed and discussed.