| The rice leaffolder, Cnaphalocrocis medinalis(Guenee) has became the main insect pest on rice crops in China, It demages rice growing seriously. Insecticide application is the major methods to control the Cnaphalocrocis medinalis (Lepidoptera:Pyralidae). Due to the ban of high toxic pesticides in China, insecticides used for control of C. medinalis have been changed greatly. Monitor the insecticide susceptibility of rice leaffolder from Nanning, Changsha and Nanjing by seeding dip assay during 2011-2013 can measure the resistance to the 13 insecticides.Thus, it can guide the reasonable use of insecticides in control of C. medinalis and slow the development of the resisitance.We continued our monitoring work from 2010 and 2011.Two years’bioassay results showed that the antibiotic insecticides showed higher toxic than other insecticides, especially the spinetoram which was registered recently on the rice leafroller gave the highest toxicity among the tested insecticides; Server new insecticides, such as chorantraniliprole, indoxacarb, metaflumizone and pyridalyle also showed high toxic to the C. medinalis; The C. medinalis exhibited the least sensitivity to monosultap and Bt. Compared with the LC50 in 2010, the susceptibilities of C. medinalis from Nanning, Changsha, and Nanjing to chorantraniliprole, metaflumizone and tebufenozide were decreased from 2010 to 2013. Some populations of C. medinalis from Nanning, Changsha and Nanjing have susceptibility variation to spinetoram, spinosad, emamectin benzoate, indoxacarb and monosultap in the same year. However, the susceptibilities of C. medinalis population from Nanjing was only significant difference in emamectin benzoate and monosultap. The LC50 values of chlorfluazuron, chlorpyrifos and Bt had no significant changes in four years.Used D-optimization mixture design to optimize the artificial diet of rice leaffolder. Taking soybean, wheat germ, casin and yeast as the factors, and the pupation rate as the optimization target. Under the limited conditions of soybean(4-8g), wheat germ(2-8g), casin(2-5g) and yeast(2-6g), pupation rate as the response value. Statistical software of Design-expert can provide an experimental scheme. Mixture regression equation and contour were analysised from the different treatments of pupation. The formula of the artificial diet was calculated by mixture regression equation. The four principal components are soybean(6.33g), wheat germ(4.71g), casin(3.08g) and yeast(5.88g), the forcasted pupation rate is 49.24%. When the rice leaffolder larvae were reared on this optimum diet at the condition of 27℃,80% RH and a 16L:8D photoperiod,40% of the tested neonate larve could complete the larvae development in about 28.8 day and became pupae. The average of pupae weight were about 19.3mg. |
