Antibiosis as a resistant mechanism to Chilo partellus (Swinhoe) (Lipidoptera: Pyralidae) in selected maize genotypes

Abstract

The stem borer Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae) is an important pest of maize in Africa and Asia. Study of the mechanisms of resistance in maize genotypes to C. partellus is useful for breeding resistant varieties. The following five maize genotypes were used: Inbred A (susceptible), Mp704, Poza Rica 7832, MBR-Fam. 37, and ER-29SVR. Leaf feeding injury, stalk tunneling and dead heart damage by C. partellus to the five genotypes grown in the screenhouse under artificial infestation were greater than the field. However, the relative differences among the genotypes were consistent in the screenhouse and the field. The genotype Mp704, Poza Rica 7832, MBR-Fam. 37 and ER-29SVR suffered less damage by C. partellus in comparison to the susceptible check. To study effects on the development of C. partellus, laboratory bioassays were conducted by incorporating the leaf powder and leaf juices of resistant and susceptible maize genotypes into a meridic diet. Larval development was slower on artificial diets containing dry leaf powders of the resistant genotypes (Mp704, Poza Rica 7832, MBR-Fam. 37 and ER-29SVR) compared with the susceptible genotype. Fresh leaf juice of the resistant MP704 was much more effective than the remaining maize genotypes in retarding the development of C. partellus larvae. Fecundity of C. partellus was adversely affected when larvae were fed on artificial diet containing leaf powders of Mp704 and ER-29SVR in comparison to the diets containing leaf powders of Inbred A, MBR-Fam. 37 and Poza Rica 7832. Data indicated that antibiosis is one mode of resistance in maize genotypes to C. parellus.