Maize Stalk Borer (Lepidoptera: Pyralidae) Damage and Plant Resistance

Three maize cultivars that had shown differences in response to Chilo partellus (Swinhoe) adults and larvae were evaluated for their relative ability to withstand larval infestation and damage. Three treatment regimes, protection by insecticides, artificial infestation, and natural infestation, were adopted. C. partellus was the predominant species during the whorl stage of crop development. Eldana saccharina Walker appeared during the tassel emergence stage and persisted through harvest. Treatment, cultivar, and interaction effects were significant for maize foliar damage, stalk breakage, and ear drop. Stalk tunneling was affected by treatment and cultivar effects but number of entrance holes per plant was affected by treatment only. A larval survival index, the ratio of exit to entrance holes per stem, was higher for ‘Inbred A’ than for the other cultivars, suggesting some antibiosis in the other cultivars. Yield reduction between the protected and infested treatments was 71.4% for ‘Inbred A’ compared with 3.1% for ‘ICZ2-CM’. Of the primary damage symptoms, foliar damage correlated better with yield loss than stalk tunneling. When the yield reduction and leaf damage responses of each cultivar were partitioned into quadrants, resistance in ‘ICZ1-CM’ and ‘ICZ2-CM’ appeared to be antibiosis perhaps together with tolerance or nonpreference, whereas ‘Inbred A’ had none of these qualities.