Abstract: Cnaphalocrocis medinalis outbreak occurred in recent years in rice production region of China. To breed and extend resistance variety in pest management, the present paper investigated the relationship of silica content, silica grain diameter and wax content in rice leaf and biochemical index in five common rice cultivars, including Yangfujing 8, Yangdao 6, Yangjing 9538, Huaidao 9 and Ningjing 1, with resistance to rice leaffolder C. medinalis, and compared the differences in biochemical responses in larvae feeding on different rice varieties using scanning electron microscope and biochemical detection. The results showed that silica content of resistant varieties, Ningjing 1 and Huaidao 8, was significantly higher than that of susceptible varieties, but there were no significant differences in silica grain diameter among different varieties. Wax content in leaf blade of Ningjing 1 was significantly higher than that of other varieties, indicating that silica and wax contents in leaf surface were associated with resistance of rice to the insect. POD and SOD activities in resistant variety were significantly higher than those in susceptible variety, while MDA level in resistant variety was significantly lower than that in susceptible variety. Correspondently, enzyme activities in rice leaffolder larvae were related to rice variety. POD and GST activities in larvae feeding on resistant variety were significantly higher than those feeding on susceptible variety, while SOD activity in larvae feeding on resistant variety was significantly lower than that feeding on susceptible variety, indicating that resistant rice varieties had toxic effects on the larvae of C. medinalis.

Key words: Rice variety, Cnaphalocrocis medinalis, insect resistance, mechanism