Dissertation > Agricultural Sciences > Plant Protection > Pest and Disease Control > Crop pests and diseases and their prevention > Economic crop pests and diseases > Fiber crop pests and diseases > Cotton pests and diseases > Insect pest > Pink bollworm

Resistance of Helicoverpa Armigera Hübner Populations to Four Pesticides and Effect of Transgenic Bt Cotton to the Resistance

Author GuoQingLong
Tutor WangKaiYun
School Shandong Agricultural University
Course Pesticides
Keywords Bollworm Resistance detection Resistance Mechanism Transgenic Bt cotton
CLC S435.622.3
Type Master's thesis
Year 2007
Downloads 231
Quotes 4
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In this study, fenvalerate, phoxim representative pesticides methomyl and endosulfan China's Shandong Tai'an, Shandong Xiajin, Hubei days door three geographic populations of cotton bollworm Helicoverpa armigera (Hübner) resistant determination; synergist law and biochemical measurements detected three populations of bollworm resistance mechanism; drip method for efficient pharmaceutical screening; transgenic Bt cotton bollworm resistance to its mechanism. The main results are as follows: 1. Using micro-drip method recommended by the FAO, the determination of the level of resistance of Shandong Tai'an, Shandong Xiajin Tianmen, Hubei three cotton bollworm populations of the four kinds of representative pesticides. The results show that: The the fenvalerate Shandong Tai'an, Shandong Xiajin, Tianmen, Hubei bollworm LD50 for 115.22μg · g -1 , 367.01μg · g -1 and 495.23μg · g -1 , compared with the susceptible population, resistance respectively of 315.8 times, 1005.8 times and 1357.2 times 3 populations of cotton bollworm to fenvalerate produced a high level of resistance . The phoxim Shandong Tai'an, Shandong Xiajin, Tianmen, Hubei bollworm LD50 for 11.929μg g -1 14.413μg · g -1 and 27.079μg · g -1 , compared with the susceptible population, resistance were 1.8 times, 2.2 times and 4.1 times, respectively, the 3 populations phoxim in low resistance or a more sensitive level. Shandong Tai'an, Shandong Xiajin, Tianmen, Hubei bollworm LD50 of methomyl were 33.696μg · g -1 and 27.547μg · g 44.982μg · g -1 -1 , compared with the susceptible population, resistance were 4.7 times, 6.2 times and 3.8 times, respectively, in the low resistance level of 3 populations phoxim. LD50 of endosulfan Shandong Tai'an, Shandong Xiajin, Tianmen, Hubei bollworm were 103.69μg · g -1 , 57.455μg · g -1 , and 25.903μg · g < sup> -1 , compared with the susceptible population, resistance were 1.9 times, 1.1 times and 0.5 times, respectively, in the sensitive level of 3 populations of cotton bollworm endosulfan. The measurement results in 2001 compared to the three populations of bollworm Insecticides have varying degrees of recession, the slump was mainly associated with the planting of transgenic Bt cotton. 2 synergist on synergies agents that bollworm resistance to fenvalerate caused mainly by bollworm in vivo function oxidase detoxification enhanced esterase activity increased and epidermal penetration reduction is caused by an important reason for bollworm to fenvalerate resistance; phoxim and methomyl resistance is mainly caused by the esterase activity increased and glutathione-S-transferase activity enhanced and reduced epidermal transmittance; the synergist was no significant synergies in a sensitive level bollworm populations endosulfan. Biochemical measurements showed that the three bollworm resistant populations in the protein content, P450 content, carboxylesterase activity of acetylcholinesterase specific activity of glutathione-S-transferase specific activity and glutathione content aspects were significantly higher than sensitive populations, resistant populations of bollworm field complex mechanisms of resistance, multi-function oxidase, hydrolase and glutathione-S-transferase enzyme detoxification capacity enhancements and passivation of the target enzyme is caused bollworm resistance to the main reason. Resistance levels between the various groups and has a close relationship with the different geographic populations of drug-resistant mechanism. 4 transgenic Bt cotton bollworm larvae survival, pupal weight, as well as the immature stage duration has a significant impact, 3d and 6d larval survival rates are significantly lower than other populations, 6d immature worm weight and pupal weight was significantly lower than the other population, not mature significantly longer than the other species. Containing transgenic Bt cotton leaves fed with 4 generations, larval survival after the stability of the normal diet, 6d Young Bugs heavy, pupal weight as well as the duration of the immature stages are significant recovery, but still slightly lower than the Xiajin populations. Indoor not in contact with any pharmaceutical under ordinary artificial diet fed field after 5 generations of resistant populations, the population of fenvalerate phoxim, off methomyl and endosulfan resistance the multiples recession rate 40.8%, 8.08%, 8.71% and 4.46%, respectively, the populations reared with artificial diet mixed with the leaves of transgenic Bt cotton bollworm 4 generation and use ordinary feed stable generation of insecticides resistance rate of decline 78.16%, 28.26%, 27.95% and 23.94%, respectively. Bollworm field populations in recent years of Chemical Insecticides recession not only with field dosage reduction, with feeding Bt cotton bollworm related. Through on biochemical measurements resistant transgenic Bt cotton on the detoxification function oxidase, acetylcholinesterase, carboxylesterase, glutathione-S-transferase enzymes than vigor differences carboxylesterase structure change is also impact resistant transgenic Bt cotton on one of the factors.

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