GROWTH OF CHILO-PARTELLUS (SWINHOE) ON DIFFERENT MAIZE CULTIVARS

Four cultivars of maize, Zea mays L. viz., CM 600, Basilocal, CM 500 a nd Kisan were examined for their relative resistance to the maize stem borer, chilo partenus (Swinhoe) in relation to nutrition. Freshly hat ched larvae of C. partellus were allowed to grow on the lear whorls of the cultivars in the laboratory at 27 +/- 2-degrees-C and 70-90% r.h. The rate of growth, food consumption and its utilization, egg laying and egg hatchability were studied. The insects showed better growth wh en fed CM 600 or Basilocal maize; this was shown by a higher percentag e pupation (56.8 and 54.8, respectively on CM 600 and Basilocal) as co mpared to (24.4 and 5.6 respectively) on CM 500 and Kisan. Pupal weigh ts were higher (40.2, 45.2, 34.4 and 32.8 mg for male pupae and 57.6, 63.7, 51.8 and 35.8 mg for female pupae), when larvae were reared on C M 600, Basilocal, CM 500 and Kisan, respectively. The growth index dec reased from 1.65 on CM 600 and 1.49 on Basilocal to 0.40 on CM 500 and 0.09 on Kisan. A better consumption and utilization of the cultivars CM 600 and Basilocal was shown as also expressed by the higher weights attained by larvae grown on these two than on CM 500 and Kisan. Growt h rate slowed down to 0.068 on CM 500 from 0.161 on CM 600 maize. A si milar trend was observed in egg-laying and hatchability of eggs. Numbe r of eggs laid per female decreased from 290 on CM 600 reared C. parte llus to 157 on Kisan reared insects and none of the eggs laid by the l atter could hatch. The degree of resistance of the cultivars to C. par tellus on the basis of nutritional factors in a decreasing order is: K isan > CM 500 > Basilocal > CM 600.