Department of Plant Breeding, Punjab Agricultural University, Ludhiana-141 004 (India).
Out of nine mazie varieties evaluated for tolerance mechanism of resistance to the maize stalk borer, Chilo partellus, only Antigua Gr. 1 and Ganga 5 resisted the attack of this pest and registered lower mean damage grade (4.7 and 4.9) than Basi local (7.8) and lower mean per cent yield loss (9.7 and 16.9) than Basi local (92.1). The resistance In these two former varieties could be attributed more to the predominant mechanism i.e., antibiosis, rather than to tolerance. In spite of 2–3 repeated releases of newly hatched larvae, these two varieties showed low larval survival (2.4 and 3.1 larvae/plant) as compared to the susceptible variety Basi local (5.4 larvae/plant). Obviously, the tolerance mechanism was rather masked, particularly in the internal feeder, C. partellus, where it was difficult to maintain the equal pest population on the resistant and susceptible varieties.
