| The dynamic of tobacco pests in Hunan Liuyang area were monitored from 2010 to 2012. Insectcide resistance level and resistance distribution of Myzus persicae and Prodenia litura collected from field were also monitored in this study. The activity of detoxification enzyme, protective enzyme and amylase between suscptible and field populations of Myzus persicae, Prodenia litura were measured respectively. The mechanism of resistance of Myzus persicae in Hunan area to phoxim and beta cyfluthrin was discussed. The main results are as follows:1. Occurrence dynamic of Myzus persicae in the field was monitored from 2010 to 2012 in Changsha (Liuyang) area, and the relationship between base of different previous crops overwintering pest and current tobacco pests was also discussed. The results indicated that, aphid strain rate and 100 strains of aphids were higher in winter radish and cabbage dish in 2011 than what was in 2012 and 2010, of which, the aphid; strain rate in winter radish dishes in 2011 was 16%,100 plant aphid was 26, respectively, aphid strains rate in winter Chinese cabbage was 26%,100 plants aphid was 42 respectively. Myzus persicae was serious in 2011 than the other two years, the highest amount per plant in 2011 was up to 4896, aphids number up to 25768. It showed that aphid number in previous crops was more, the tobacco aphid was more serious. While the number of natural enemies in 2011 was relatively more than other two years, mainly adult ladybug, Syrphidae, lacewing adults and spiders, therefore the number of mummified aphids this year was significantly higher than that in other two years, especially in the early May, the highest amount of stiff aphids per 100 plants up to 5241. Chafer (grub) number was high when previous crops was pepper Tanaka and number of Tanaka snail was high when previous crops was tobacco and eggplant.Sex pheromone attractant was used to monitor the dynamic occurrence of Spodoptera litura, tobacco budworm, Agrotis Ypsilon and Helicoverpa armigera in tobacco field from 2010 to 2012 in Changsha (Liuyang) area. The results showed that adult Spodoptera litura were occurred in early May in this region and the maximum was in 2012. Generating capacity of tobacco budworm in 2012 was higher than the other two years, adults were occurred in late March. Cotton bollworm moths were occurred in the mid to late March and the maximum was in 2012. Agrotis Ypsilon were serious in 2011 and 2012 and adults were occurred in the late February.2. The insecticides resistance level of Myzus persicae populations were monitored in Liuyang, Hunan Ningxiang, Chenzhou Guiyang and Xiangxi Longshan tobacco areas. Four tobacco aphid populations all have higher resistance to imidacloprid especially of Liuyang population which compared with the susceptible population, resistance is 69.07 times. Four tobacco aphid populations all have high resistance to imidacloprid especially of Ningxiang population which compared with the susceptible population, resistance up to 21.03 times, followed by the Liuyang population which resistance up to 11.33 times. Liuyang population also had higher resistance to Lambda-cyhalothrin, resistance to 10.14 times. In addition to Xiangxi Longshan population showed low resistance to phoxim, the remaining 3 kinds of populations were still in the stage of decreasing sensitivity. Four kinds of aphid populations showed a reduced sensitivity to Methomyl. The insecticides resistance level of Spodoptera litura populations to Emamectin and cyhalothrin were monitored in Ningxiang tobacco area. Spodoptera litura populations showed higher resistance to these two insecticides. The resistance to Emamectin up to 30.15 times and to cyhalothrin up to 47.28 times compared with the susceptible population.3. The activities of gultathione S transferases (GSTs), carboxylesterase (Care), Acetylcholinesterase (AChE) and mixed function oxidase of the Myzus persicae were examined. The activity of detoxification enzyme in Liuyang population was found to be greater than others, followed by Ningxiang population. The activity of detoxification enzyme in Ningxiang population was obvious different from susceptible population. Moreover, the activities of protective enzyme (SOD, CAT and POD) of resistant populations were all greater than sensitive population. The sensitivity to two insecticides of Emamectin Benzoate and cyhalothrin and the four detoxification enzymes (acetylcholine esterase (AchE), carboxylesterase (CarE), gultathione S transferases (GSTs), mixed-functional oxidase (MFO))activities of Spodoptera litura from Ningxiang tobacco area were tested with bioassay and biochemical methods, respectively. This field population was showed to have high resistance to Emamectin Benzoate and cyhalothrin. The activities of all the four detoxification enzymes of the Ningxiang field population improved significantly than that of sensitive population. This meant that the AchE, CarE, GSTs and MFO and protective enzyme played important roles in insecticide resistance to the Myzus persicae and Spodoptera litura in Hunan area.4. Activity of ?-NA carboxylesterase between the susceptible strain and resistance to phoxim and cyhalothrinstrains was studied. The results showed that there was significant differences between susceptible and resistant strains. Activity of a-NA carboxylesterase were 0.477U/mg.pro.t,1.931 U/mg.pro.t and 1.542 U/mg.pro.t. Among them, resistance to phoxim strain specific activity is 4.05 times the Fujian susceptible strains, resistance to cyhalothrin strain specific activity is 3.23 times the Fujian strain. While there was no significant differences in?-NA carboxylesterase activity between susceptible strain and resistance to phoxim and to cyhalothrin strain. Activity of ?-NA carboxylesterase were 1.013U/mg.pro.t,1.140 U/mg.pro.t and 0.994 U/mg.pro.t. There was significant differences between susceptible and resistant strains in mixed function oxidase. Activity of mixed function oxidase between susceptible and resistance to phoxim and cyhalothrinstrains were 0.312U/mg.pro.t,0.504U/mg.pro.t, 0.683 U/mg.pro.t. Among them, resistance to phoxim strain specific activity is 1.62 times the Fujian susceptible strains, resistance to cyhalothrin strain specific activity is 2.19 times the Fujian strain. The three strains of DNA were amplified by PCR, there were two bands of esterase gene of Myzus persicae in 574bp and 865bp respectively, that was, in the resistant strains of Phoxim and cyhalothrin, esterase gene Myzus persicae no amplification. Three strains of DNA were PCR after amplification, there were two bands of Na in 300bp and 600bp, that was, Fujian susceptible strain and resistance to lambda cyhalothrin strains of Myzus persicae were resistant heterozygo. |
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