Resistance Monitoring Of Spodoptera Litura(Fabricius) In Sichuan Region And The Effect Of Temperature And Insecticide On Development Of Experimental Population

Spodoptera litura （Fabricius） is a kind of world widely serious agricultural pests, with the characteristics of wide hosts and quick propagation, and the resistance of S. litura is becoming more and more serious. To understand the resistance level and mechanism of traditional pesticides on S. litura field populations in Sichuan, and growth characteristic of Laboratory sensitive strains （Lab-Sus） at different temperatures and pesticides, this paper monitored the resistance levels of five kinds of insecticides against field populations of S. litura collected from seven districts of Sichuan and further studied the resistance mechanism. The age-stage sexes life table of field populations and Lab-sus in the same indoor conditions, and two-sex life table of Lab-Sus treated with different temperatures, were also investigated. Meanwhile, the growth and development characteristics of Fo and Fi generations of S. litura of Lab-sus treated with the sublethal dosage of chlorantraniliprole, a novel ryanodine receptor insecticide, were systematically studied with methology of age-stagelife table. The main results are listed as following:1 Resistance monitoring and biochemical mechanism research on S. litura in SichuanThe sensitive baselines of beta-cypermethrin, chlorpyrifos, indoxacarb, emamectin benzoate and methoxyfenozide on S. litura of Lab-Sus were constructed with diet incorporation bioassays. The toxicities of five insecticides on seven field populations from different districts in Sichuan Province, including SL, LS, MS, QW, XD, SN and JT, were assayed. The results indicated that all field populations of S. litura had very high resistance level on beta-cypermethrin （with the resistance ratio of 237.9-432.3 folds） and low and medium resistance level of all field populations on chlorpyrifos （with the resistance ratio of 8.3-22.6 folds） were also demonstrated. All field populations, except for the Leshan populations （with the resistance ratio of 6.2 times）, were sensitive or lower sensitive indoxacarb. The resistance levels of all field populations to emamectin benzoate and methoxyfenozide were sensitive. Synergist experiments showed that the synergism effects of maleic acid ethyl ester （DEM） on beta-cypermethrin, chlorpyrifos and indoxacarb against the field populations （including SL, MS and LS） and Lab-Sus, were not significant. However, the efficiency ratios of pepper butyl ether （PBO） and triphenyl phosphate （TPP） on beta-cypermethrin, chlorpyrifos to SL and MS populations were significantly higher than those of Lab-Sus, but no significance in indoxacarb. The detoxification enzyme activity showed that the carboxylesterase （CarE） and Multi-function oxidase （MFO） activities of S. litura have been promoted significantly when the tested insect were dripped some quantitative acetone solution of chlorpyrifos and beta-cypermethrin, meanwhile enzyme activities of field populations were significantly higher than thoes of Lab-Sus.2 Construction the two-sex life table of field populations and Lab-SusThe growth and development parameters of Shuangliu populations and Lab-Sus were analyzed and found that the every development period of S. litura in Shuangliu populations was significantly longer than those in Lab-Sus. Moreover, the average spawning and livability of S. litura adult females of Shuangliu population were higher than those in Lab-Sus. However, the intrinsic rate of increase （r） and finite rate of increase （λ） of S. litura in Lab-Sus were significantly higher than those in Shuangliu population. The net reproductive rate （R₀） and average generation cycle （T） of S. litura in Shuangliu population were significantly higher than those in Lab-Sus.3 The growth and development characteristics of S. litura of Lab-Sus at different temperaturesThe growths and developments of Lab-Sus at different temperatures were significantly different, which of the treatment of 20±1℃ was the slowest, followed by the treatment of 27±1℃ and 30±1℃. However, the livability of S. litura larvae had displayed the treatment of 27±1℃ >20±1℃ >30±1℃ and the average spawning of S. litura adult females showed 20±1℃ >27±1℃ >30±1℃. The intrinsic rate of increase （r） and finite rate of increase （λ） of S. litura in 30±1℃ was the highest, followed by the treatments of 27±1℃ and 20±1℃. Meanwhile, the intrinsic rate of increase （r） and finite rate of increase （λ） in 20±1℃ was significantly different from in 27±1℃ and 30±1℃. The net reproductive rate （Ro） in 27±1℃ was significantly higher than those in 30±1℃ and 20±1℃ . The Mean generation time （T） of three treatments showed 20±1℃>27±1℃ >30±1℃ , and were significantly difference among the three treatments （P<0.05）.4 The growth and development characteristics of S. litura Fo and Fi genenrations of Lab-sus treated with the sublethal dosage of chlorantraniliproleThe sublethal dosage of chlorantranilipro on Lab-sus of S. litura was assayed with diet incorporation and the LC₁₀ and LC₃₀ vaules were 0.020 μg/g and 0.038 μg/g, respectively. The growth parameters of Fo generation displayed that the eggs period, larvae period and pupae calendar period in the treatment of LC₃₀ were the longest, followed by the treatments of LC₁₀ and blank control. The adult lives of blank control were longer than those in other two treatments; what’s more, the average spawning of females was also significantly more than those in other two treatments. The intrinsic rate of increase （r） and finite rate of increase （λ） in blank control were the highest, followed by the treatments of LC₁₀ and LC₃₀ Inaddition, there was significant differences between the three treatments （P<0.05）. The net reproductive rate （Ro） in blank control was significantly higher than those in LC₁₀ and LC₃₀ treatments. However, the Mean generation time （T） of three treatments showed that LC3o> LCio>CK, and were significant each other （P<0.05）.Lab-sus of S. litura treated with the LC₁₀ and LC₃₀ dosage of chlorantraniliprole, the growth and development of Fi generation is significantly different with the treatment of blank control. The egg period in the treatment of LC₃₀ was longer than those of LC₁₀ and CK treatments, while the hatching rate was significantly lower than those of LC₁₀ and CK. Moreover, the larva stage period （L1-L6） of LC₃₀ treatment was significantly longer than those of LCio and CK. The adult life in LC₃₀ was shorter than other two treatments, while which of CK treatment was the longest （P<0.05）. The average spawning of females showed CK>LCio>LC3o and there was significant difference with each treatments （P<0.05）. The intrinsic rate of increase （r） and finite rate of increase （λ） in CK treatment was the highest, followed by the treatment of LC₁₀ and LC3oand significantly different （P<0.05）. The net reproductive rate （Ro） in CK treatment was significantly higher than those in LC₁₀ and LC₃₀ treatments. However, the Mean generation time （T） of three treatments showed that LC3o> LCio>CK, and was significant each other （P<0.05）.