Abstract: The mechanism of rice varietal resistance to the yellow stem borer (YSB), Scirpophaga incertulas, was investigated and analyzed. There were significant differences among development rates and weight gain when YSB neonates fed on rice varieties with different resistant levels. The varieties Shan-you 63 (hybrid indica), Zhendao No. 2 and 92.109 (japonica) evidently inhibited the growth of YSB in comparison with other varieties tested. It was found that YSB larval performance was obviously correlated with the interval vascular bundles and the width of sheath ridge in the outer leaf sheath on primary stem of the rice tested rather than the contents of essential amino acids and reductive carbohydrate in these rice plants.

Key words: Scirpophaga incertulas, growth, rice resistance, interval between vascular bundles, free essential amino acid