Monitoring Of Insecticde Resistance And The Research On Artificial Diets For Rice Leaffolder, Cnaplocrocis Medinalis (Guenee)(Lepidoptera:P Yralidae)

The rice leaffolder, Cnaphalocrocis medinalis(Guenee) is one of the most important pests on rice crop in China. Chemical control is the major measurement for suppression of Cnaphalocrocis medinalis (Lepidoptera:Pyralidae) damage. In recent years insecticides used for control of C. medinalis in China have been changed greatly. Several new chemicals have been introduced for control of C. medinalis. However, there was litlle data about insecticide resistance of C. medinalis. Using the rice seeding dip assay established by our laboratory, the insecticide susceptibility of rice leaffolder in2011and2012were measured to guide the reasonable use of insecticides in control of C. medinalis.Bioassay results in2011and2012showed that the antibiotic insecticides exhibited higher toxicity than other insecticides, especially the spinetoram which was registered recently on the rice leafroller gave the highest toxicity among the tested insecticides; Indoxacarb, chlorfluazuron and chorantraniliprole also demonstrated higher toxicity to C. medinalis; C. medinalis exhibited the least sensitivity to monosultap and Bt. Compared with the LC50in2010, the susceptibilities of C. medinalis from Nanning, Changsha, and Nanjing to chorantraniliprole, metaflumizone and tebufenozide were decreased from2010to2012. There was a difference in annual sensitivity of spinetoram, spinosad, indoxacarb, abamectin, and emamectin benzoate in geographic populations. However, the LC50values of chlorpyrifos, chlorfluazuron, monosultap and Bt had no significant changes in three years.The CTC of binary mixtures among emamectin benzoate, tebufenozide, chlorpyrifos, chlorantraniliprole, spinetoram, indoxacarb were assayed by rice seedling dipping method. Thirty nine ratios of8binary mixtures were assayed. The CTC of ratio C(1:1) and ratio D(1:2) in combination#6are286and281, The CTC of ratio B(1:2) in combination#2is200. The results showed that these two mixtures have synergism effect and may have certain application prospects. The artificial diet recipe of rice leaffolder was optimized by applying the design of quadratic orthogonal rotational combinations. An optimum diet recipe was obtained by establishing quadratic regression model taking pupation rate of rice leaffolder as the objective function. The result showed that proportions of rice leaf powder, wheat germ powder, corn powder, casein and yeast affected the rate of pupation of rice leaffolder larvae. The optimum proportions of the components were:rice leaf powder3g, wheat germ powder8g, corn powder4g, casein4g and yeast4g in135g of diet.When the rice leaffolder larvae were reared on this optimum diet at the condition of27℃,80%RH and a16L:8D photoperiod,25.6%of the tested neonate larve could complete the larvae development in about26.9day and became pupae. The pupae weight were about16-22mg. The rate of pupation and pupae weight were obviously higher, and the larvae duration slightly shorter in this research than that reported in previous study.