Mechanism Of The Outbreak Of Rice Borers In Shanghai Area

Rice is important crop in China, the growing area of which is about 1/3 of all crops and the total output of rice is about 45 percent of the total output of grain. Rice borer, mainly included rice stem borer, Chilo supprssalis Walker, and yellow stem borer, Scirpophaga incertulas Walker, are the two major pests on rice, which have occurred for a long time and distributes in many areas and cause serious damage.In recent years, as the adjustments of farming system is conducted, the rice crop is increasingly infested by the two kinds of rice borer. From 1998, in Shanghai, the stem borers increased greatly. So it is necessary for us to make clear what on earth factors could induce such results and which one was the key factor, all of these could help us to understand the stem borers population dynamics, and give some advices for IPM of the stemborers.The relationship between the rice seeding date and the occurrence of the yellow stem borer was investigated in Pudong, Shanghai. It showed that there was obvious relationship between the two factors, which when it was seeded at May 23th, before and later, the injuries was the most small, and the rice output decreased fewer compared with the May 10 th. At the same time we explain the reason, from the decrease of the adults, attracted by the lamp day by day, which could oviposite and do harm to the rice.The difference and mechanism of the four rice varieties resistance to rice stem borers (Chilo suppressalis Walker and Scirpophaga incertulas Walker) were investigated in Shanghai rice area.The results indicated that there was obvious difference of varieties resistance between Xiushui-04, which was the main one from 1980 to the early stage of 1990s, and the other three varieties, Hanyou-xiangqing , Huayu-1 and 98110, which were the main varieties...