VARIETAL RESISTANCE: BIOLOGICAL EVALUATION AND SCREENING OF CERTAIN RICE ENTRIES AGAINST THE RICE STEM BORER, CHILO AGAMEMNON BLES.

Sixteen rice varieties and promising lines were evaluated at two growth stages, for resistance to feeding by the rice stem borer; Chilo agamemnon Bles. larvae using laboratory methods. Study reported here showed that :- A)At tillering stage Larval mortality: Giza 167, GZ 4294-10-2, Todorokiwase, GZ 4256‌7-4-7 and GZ 4122-23-4-2 were the most resistant entries causing from 20.0 to 55.6% larval mortality. Larval duration: Todorokiwase, GZ 4294-10-2 and Giza 176 were the most resistant entries resulting in longest developmental periods of larvae ranging from 32.3 to 35.2 days. Pupal duration: Todorokiwase and Giza 176 were the most resistant entries resulting in longest duration periods of pupae ranging from 7.0 to 7.7 days. Pupal weight: Todorokiwase and Giza 176 appeared to be the most resistant entries resulting in least weights of pupae ranging from 40.2 to 24.6 mg. Adult longevity: Telle Hamsa and Toride-1 were the most resistant entries with longest adult longevity ranging from 9.0 to 7.6 days. B)At flowering stage Larval Mortality : GZ 4071-16-2-1 and Kagahikari were the highest resistant entries causing 42.6 and 35.0% larval mortality. Larval duration:GZ 4071-16-2-1 and Kagahikari were the highest resistant entries with 34.6 and 33.2 days as longest duration of larval feeding. Pupal duration: GZ 181 and Kagahikari were the highest resistant en‌tries with longest pupal duration ranging from 8.9 to 7.2 days.