Studies On Chemical Control Techniques For Major Insect Pests In Single Cropping Rice Region

Rice is the most important food crops in China, The stable production of rice is essential to main food security. However, frequent and serious occurrence of rice pests is an obstacle for rice production. Plant protector had been looking for effective integrated control for rice pests. Chemical control is always one of the main methods in Integrated management of rice insect pests and irrational use of pesticides had been led to a series of problem such as drug resistance, pest resurgence, environmental pollution and pesticide residues. This article chose three kinds of representative pesticides, and compared the killing effect of main pests and natural enemies with different dosage, spraying time. At the same time, the host selectivity of the rice stem borer, chilo suppressalis (walker), was researched. Now, some related work has been done and the main results are summarized as follows:1. Control efficiency of different pesticides against insect pests and evaluation of their safety to predatory spiders in rice fieldsThe researsh selected40%chlorpyrifos, abamectin-chlorpyrifos and chlorantraniliprole to protect the plant of rice, and compared quantitative change of white backed rice plant hopper(WBPH), spider and chironomid midge under the treatment of the high concentration and low concentration of pesticide and the treatment of different spraying time with the same concentration at single late rice. The field test results showed that it is not obvious for this three kinds of pesticides to kill chironomid midge, and basically they don’t affect the development of chironomid midge. According to control efficiency on WBPH in rice field, abamectin-chlorpyrifos was the best than the others when diluted750times, and the control efficiency were74%,56%,53%and23%when sampled at13,18,23and28days. When compared killing effect of spiders with the same concentration, spaying after transplanting was better than spaying before transplanting. Different pesticide has a different killing effect on spider, and chlorpyrifos and abamectin-chlorpyrifos had a much higher killing effect than chlorantraniliprole. And the killing effect had no significant difference when the concentration was raised before the transplanting, it was raised when after the transplanting. Compared the different treatments with pests and spiders, and the cost which used in rice seed-beds and paddy fields, the conclusion was that choosing a proper kind of pesticide and increasing the concentration before transplanting the rice seedling was better than after the transplanting.when spaying pesticides2. The effect of three different pesticides on major pests and spiders of rice fields at jointing stageThe study selects chlorpyrifos, abamectin-chlorpyrifos and chlorantraniliprole to protect the plant of rice at jointing stage, and evaluate their safety to predatory spiders in rice fields. The field test results showed that the three kind of pesticides had a good control efficiency on Sogatella furcifera, and they would do better when a higher concentrations were used. Chlorpyrifos and abamectin-chlorpyrifos had a better lasting validity and readily availability than chlorantraniliprole’s. Chlorpyrifos and abamectin-chlorpyrifos which had higher concentrations enhanced the control efficiency. but these three kinds of pesticides had a little protection for rice leafhopper. So, they were not recommend to use when to control rice leafhopper. The three kinds of pesticides had some killing effect on the main spiders in paddy field and abamectin-chlorpyrifos had a strongest killing effect, althouth chlorantraniliprole had a weakest killing effect.3. Comparing study on oviposition preference of rice and water-oat population of rice stem borer, Chilo suppressulis.The experiment of oviposition preference was studied in the oviposition cage (length:width: height=2m:2m:2m; covered by nylon gauze) in laboratory. The results showed that the two populations preferred laid eggs on rice and water-oat rather than wheat and bckmannia syzigachne. And rice population preferred lay eggs on rice, and water-oat population preferred water-oat, which meant the two populations preferred lay eggs on its own host. Also, the average number of per eggs laid by the two populations on rice and water-oat was much bigger than others, which meant the egg masses could be much bigger when the two populations laid eggs on rice and water-oat. And the average number of per eggs laid on these four kinds of plants by water-oat population was much bigger than rice population’s, which meant water-oat population had a better capability of oviposition than rice population’s...