Studies on Antibioses Mechanism of Resistance to Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) in Maize, Zea mays L.

The stem borer Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) is an important pest of maize in Asia and Africa. Study of the mechanisms of resistance in maize genotypes to C. partellus is useful for breeding resistant varieties. The following six maize genotypes were used: VIM 308, VIM 313, VIM 319 and VIM 322 (Highly resistant) and VIM 325 and VIM 329 (Resistant) along with susceptible (Basilocal) and resistant check (CM500). Growth and development of spotted stem borer, Chilo partellus (Swinhoe) was studied under screen house conditions by releasing neonate larvae of C. partellus on 20-dayold seedlings of maize genotypes. Antibiosis was observed in terms of low larval survival, long larval and pupal periods, reduced pupal mass and low growth index in three Maize genotypes i.e., VIM 325, VIM 308 and VIM 322. The moths emerging from these genotypes were deformed, less active and did not attain the normal size. Antibiosis is an important mechanism of resistance in these genotypes against C. Partellus and can be useful in a program of breeding maize for resistance to C. partellus. Slower larval development on the resistant plants would prolong the exposure to predators and parasites which might reduce populations of this insect.