Monitoring Insecticide Resistance And Studies On Resistance Physiological And Biochemical Mechanisms Of Thiamethoxam In Myxus Persicae

The Myzus persicae (Sulzer), is one of the important agricultural pests of the world, causing direct as well as indirect damage to many plants of the world in the past few decades.The development of resistance is a result of the selection pressure exerted on sprayed populations increasing the frequency of resistance individuals. In this paper, the monitoring of the field resistance, resistance mechanisms to Thiamethoxam and epidermal penetration rate were carried out.1. The studies were carried out to evaluate resistance in the populations of Myzus persicae from six districts of Hunan and Guangdong Province to7insecticides using a standard leaf dip bioassay method.Six field populations of Myzus persicae have high level resistance to imidacloprid. Myzus persicae populations collected from chenzhou, shaoguan,meixian and huiyang have low level resistance to endosulfan.The RR of Myzus persicae populations were9.6-fold and7.7-fold in tianhe district and huiyang district. Myzus persicae populations of chenzhou collected from cabbage showed low level resistance to carbosulfan (RR=8.1).2.The resistance to thiamethoxam in Myzus persicae was the lowest in a population collected from Xiong Fengshan nature reserve of chenzhou.As a relatively sensitive strains,25%thiamethoxam(WP) was used to select this population. The selection population obtained75.6folds of resistance compared with its unselected population. The activity of glutathione S-transferase in susceptible and resistance strains were3.1275and3.2159μmol/(min-mg pro),no significant difference. The activity of acid phosphatase in susceptible and resistance strains were105.2736and164.9327μmol/(30min-mg pro), significant difference. The activity of Alkaline phosphatase in susceptible and resistance strains were1.6863and3.5481μmol/(30min-mg pro), significant difference. The activity of carboxylesterase in susceptible and resistance strains were0.4635å'Œ2.8376μmol/(30min-mg pro), significant difference. The activity of multi-function oxidase in resistance strain was2.03times than the susceptible strain.3. The synergism of TPP,PBO and DEM on thiamethoxam was tested.The PBO and TPP showed obvious synergism on thiamerthoxam (SR2.35and1.48, respectively).However, no obvious synergism was found with DEM.168h after field application, control effect of thiamethoxam lg/hm2mixed with PBO was obvious than thiamethoxam1.25g/hm2.