Study On Resistance Monitoring And Its Resistance To Beta-cypermethrin In Spiraling Whitefly

The spiraling whitefly (Aleurodicus dispersus Russell) is an invasive dangerous pest to agriculture and forestry which has been invaded Taiwan and Hainan province successively. Due to the lack of effective ecological and physicalcontrol measures, chemical control is still an important means for controling the pest. And the generation and development of resistance has become an important and unavoidable issue during the process of applying chemical control. For this reason, the activity of the esterase, multifunction oxidase and glutathione S transferase in adults of different generations were tested by the method of enzyme labeling kinetic base on the laboratory resistance selection of beta-cypermethrin which was carried out follow generations with the method of population screening of spiraling whitefly.The resistance levels and Sensitivity of spiraling whitefly in different generations to beta-cypermethrin were tested by Potter spray method and Tabashnik threshold analysis method, then calculated its realized heritability of resistance (h2) to beta-cypermethrin,and assessed the resistance risk by estimating the rates of resistance development in spiraling whitefly under different selection pressure of beta-cypermethrin. The LC50 value of spiraling whitefly populations to pyrethroids, organic phosphorus, neonicotinoids and microbial sources pesticides were tested by Potter spray method, those populations feed on different host plants were collected from different geographic regions and different ecological environments. This paper is aimed at understanding the resistance mechanisms and resistance risk to pesticides, then control the occurrence and development of resistance in field populations of spiraling whitefly. Main results were shown as follows:1. After the spiraling whitefly were breeding under the pressure of beta-cypermethrin for 5 generations, the activity ratio of the 5th generation compared the first generation to esterase,multifunction oxidase and glutathione S transferase were 3.2385.3.0288 and 1.1461 times, respectively, suggesting that the resistance of spiraling whitefly to this pesticide has significantly positive relationship with the activity of esterase and multifunction oxidase, and has no obvious relationship with the glutathione S transferase.2. After the spiraling whitefly were breeding under the pressure of beta-cypermethrin for 5 generations, the resistance of spiraling whitefly to beta-cypermethrin increased 2.7932 times. The resistance reality heritability of spiraling whitefly to beta-cypermethrin was h2=0.2151 calculated by the threshold-like analysis of Tabashnik, predicting that the resistance of spiraling whitefly to beta-cypermethrin in different selection pressure will increases for 10 times after the spiraling whitefly developed for 6.6071 generations when the selection pressure is similar to indoor breeding (the slopes of the LC50 line before and after screening are all 2.5,δp= 0.4000), the outside environmental interference factors (extreme weather.insect communication, etc.) are excluded and each generation of the field populations are controled using beta-cypermethrin and the control effect is 90%.3. To December 2010, the field populations of spiraling whitefly in all monitored geographical regions were still relatively sensitive stage to beta-cypermethrin. chlorpyrifos, acetamiprid and avermectins and the relative resistance ratios were 1.0848～2.4796, 1.9632～3.0820.1.0519～1.5691 and 1.1878～2.1472 times, respectively.4. To December 2010, the resistance of spiraling whitefly has not yet formed to lambda-cyhalothrin. beta-cypermethrin. deltamethrin. malathion, methidathion, chlorpyrifos, imidacloprid, acetamiprid, avermectins and emamectin-benzoate in host plants of all monitored field populations, and its resistance ratios were 1.2434～2.1153, 1.2141～1.7768.1.0494～1.4116.1.4178～1.9734.2.6359～4.2203,2.0825～3.2580.1.1389～1.6105.0.9922～1.1910,1.4186～2.0466 and 1.5309～2.2973, respectively.5. To December 2010. the field populations of spiraling whitefly in all monitored biological environments were still relatively sensitive to lambda-cyhalothrin, beta-cypermethrin. deltamethrin, malathion, methidathion, chlorpyrifos, imidacloprid, acetamiprid. avermectins and emamectin-benzoate. the resistance was not yet clcar.and their resistance ratios were 1.7002～1.8814,1.6464～1.9050,1.2833～1.5988.1.5340～1.8297. 3.0843～3.5733,1.9381～2.6374,1.2092～1.2346,1.0016～1.2553,1.4864～1.8437, and1.804 3～2.1733, respectively.