| Sesamia inferens(Walker), as one kind of widely-distributed polyphagous pests, has attained a main pest status in some rice field region of China in recent years, which was caused by many factors, such as climate changes, pesticides application, and etc. Furthermore, the cultivation and promotion of hybrid rice was viewed as one important factor for its population growth. Our hypothesis was conducted based on:1) higher contents of favorite nutrient in hybrid rice to S. inferen should be checked when compared with the traditional japonica rice.2) lower contents of secondary resistant substance would be found in hybrid rice to S. inferen.3) physical characteristics of hybrid rice are more beneficial to the boring of S. inferens. Thus, ten common varieties of rice, divided into three categories as traditional indica and japonica rice, and hybrid rice, in Jiangsu province were selected to investigate their impacts on population growth of S. inferens in a semi-natural condition, and the biochemical and physiological changes in rice under the feeding of S. inferens. Our results are as follows:1. Effects of 10 rice varieties on the population growth of S. inferensEffects of 10 varieties of rice (hybridrice:Changyou5, Wandao153, Fengyouxiangzhan; traditional indica:Yangdao6, MH63; traditional japonica:Ningjing4, Huaidao5, zhendao15, wuyunjing24, Yangjing4038) on the population growth of S. inferens in a semi-natural condition were checked. Our results showed that, the larval survival, pupal weight, and fecundity of S. inferens feeding on hybrid rice were significant higher than that on traditional indica, and then on traditional japonica. The survival rates of S. inferens from Fengyouxiangzhan and yangdao6 were significantly higher than that on japonica varieties; the pupal weight and fecundity from Fengyouxiangzhan was obvious higher than on Huaidao 5 and Ningjing4. It indicated that Fengyouxiangzhan was more helpful to the population growth of S. inferens, compared to Huaidao5 and Ningjing4.2. Comparison of contents of resistant and susceptible substances, and boring characteristic of S. inferens among 10 rice varietiesSome biochemical and physiological substances, e.g. soluble sugar, soluble protein, amino acids, flavonoids, phenolic acids, oxalic acid, and enzyme activity, functioned as resistant or susceptible to S. inferens were investigated quantitatively. We found that content of soluble sugar in Fengyouxiangzhan and Yangdao6 was significantly higher than others, and it was a significantly correlation between the content of soluble sugar and the survival rate, fecundity of S. inferens. Contents of the total amino acid in Fengyouxiangzhan and Yangdao6 were significantly higher than that of Ningjing4 and Huaidao5. A lower content of silicon in Wandao 153 and a higher in Yangjing4038 were found. Meanwhile, the larva of S. inferens bored into the stalk of rice of Yangjing4038 in a more short time and higher survival rate than that on Wandao 153. Contents of secondary substances in traditional japonica were significantly higher than that of hybridrice. Content of MDA was rising, while activity of POD, SOD were decreasing.3. Effects of 10 rice varieties on contents of hormone and yolk protein of S. inferensSome indicators of the worms, e.g. hormone, yolk protein, as fecundity-related substances of S. inferens were investigated quantitatively, our result showed that the content of juvenile hormone of S. inferens feeding on hybrid rice were significant higher than that on traditional indica, and then on traditional japonica. The content of larvae juvenile hormone of S. inferens from Fengyouxiangzhan were significantly higher than that others; the content of adult juvenile hormone from Fengyouxiangzhan was obvious higher than that on Ningjing4 and Yangjing4038. The molting hormone of S. inferens from Changyou5, Fengyouxiangzhan was lower than that on Yangjing4038, Wuyunjing24, Zhendaol5. The content of yolk protein of S. inferens from Fengyouxiangzhan, Yangdao6, Changyou5 Wuyunjing24 was significantly higher than Ningjing4, which was consistent with fecundity of S. inferens. |
