Screening of Maize Germplasm for Resistance Against Stem Borer (Chilo partellus Swinhoe)

摘要

Maize stem borer, Chilo partellus Swinhoe, is one of the most important biotic (insect) stresses for maize production in Nepal. Host-plant resistance is the most important approach in developing effective integrated pest management (IPM) system against this pest. Resistance of eighteen maize genotypes, including both enzootic and exotic, was evaluated by natural infestation method, partially based on CIMMYT screening method. Response of maize plants to the insect was categorized into resistant, moderately resistant, moderately susceptible and susceptible on the basis of percentage of undamaged, slightly damaged, moderately damaged and highly damaged plants for a given genotype. No reduction in yield was observed from the undamaged and slightly damaged individuals, whereas reduced or no yield was estimated from the moderately to highly damaged plants. Resistance of the tested maize genotypes differed significantly and compared clearly. Genotype "S97TLYGHAYB(3) ", possessing 4.9% of moderately to highly damaged plants, was termed to be the most resistant among the six genotypes from CIMMYT and "Gaurab" (hybrid), possessing 53.8% of moderately to highly damaged plants, was found to be the most susceptible one among the two susceptible maize genotypes. Since stem borer infestation is very high during every summer at National Maize Research Program (NMRP), Rampur it is suggested to screen the genotypes under natural infestation condition, which is very simple and useful in areas where there is no artificial insect rearing facility and where stem borer infestation levels are high and predictable.