| The research determinate the resistance levels of the field populations of exigua Hubner to methoxyfenozide in different regions in Hunan Province, and investigate the toxicity mechanism of methoxyfenozide to the exigua Hubner, and the resistance risk of exigua Hubner to methoxyfenozide with systematic. Also measured the synergist of 3 synergies mixed with methoxyfenozide to the exigua Hubner. Mastered the resistance levels of the six areas field populations of exigua Hubner to methoxyfenozide in Hunan Province, Initially know the methoxyfenozide on exigua Hubner and exigua Hubner mechanism of toxicity of methoxyfenozide resistance risk, Initially know the resistance levels of exigua Hubner to methoxyfenozide and the toxicity mechanism of methoxyfenozide to the exigua Hubner, provied the scientific basis and guidance of exigua Hubner resistance management.The main results as follows:1.Toxicity of methoxyfenozide to exigua Hubner larvae Spodoptera exigua and the synergism of DEM,PBO and TPP to methoxyfenozide were detected by topical application recommended by FAO in Changsha,Liuyang, Yueyang, Yiyang, Xiangtan and Zhuzhou six regional, the results indicated that the LD50 of methoxyfenozide to Spodoptera exigua 3th instar population of Changsha,Liuyang, Yueyang, Yiyang, Xiangtan and Zhuzhou six regional were 4.67μg/g,8.54μg/g,1.33μg/g,14.78μg/g,1.20μg/g and 10.60μg/g. It can be seen clearly that the toxicity of methoxyfenozide to field population of Spodoptera exigua has not obviously difference.2. In order to expound the mechanism of methoxyfenozide of Laphygma exigua Hubneras (Spodoptera exigua) to methoxyfenozide. By analyzing the changes of glutathione-S-transferase and esterase, and cytochrome P450 in the 4th instar larvae of Laphygma exigua Hubner by biochemical analysis. And the results indicated that after treatment by LD25 and LD50, Carboxylesterase activity in the 1-6 hours was Carboxylesterase in vivo treatment group was significantly higher than reference standard system activity, and the treatment group with LD50 was higher than LD25, then ther were decreased slowly,24h after, the activity was the lowest, and then increased slowly, but at 6h after, the activity was the highest; The use of methoxyfenozide to Spodoptera exigua and its LD25 and LD50 concentration for treatment, the activity in GST was significantly increased in the 0-24 hour period,6 hours later, the activity was the highest,and then decreased slowly.And 48h after treatment, the activity was the same with the CK, With methoxyfenozide treatment, within 12 hours of the 4th instar larvae of Laphygma exigua Hubner cytochrome P450 content of the body significantly, the maximum effect in 24 hours, then recovered slowly.3. The synergism of DEM,PBO and TPP to methoxyfenozide were detected by topical application recommended by FAO,and the resunlts indicated that 24h after treatment. The synergist of three species on resistant and sensitive populations have a certain synergy, but not obvious, and the synergy of TPP is the best, and the synergy times on resistant and sensitive populations is 2.53 and 1.37 respectively. When after 48h, the synergy of tree synergist all have a abviously increase, the synergy of TPP is the best, and the synergy times on resistant and sensitive populations is 4.00 and 1.86 respectively. Followed is the PBO, and the synergy times on resistant and sensitive populations is 2.88 and 1.29 respectively. More over, either after 24h or 48h, the synergy of the three synergist on resistant populations are better than on the sensitive populations.4. Laphygma exigua Hubner resistance to methoxyfenozide eliminating the election by Micro drip recommended by FAO. The results indicated that exigua Hubner on methoxyfenozide resistance level at a low level resistance phase, eliminating the election by 12 generations, produced only 6.58 times the resistance, and before the 6th generation of very slow development of resistance, the first After six generations, resistance development rate has significantly improved.5. Comparing the glutathione-S-transferase and esterase, and the specific activity of cytochrome P450 in sensitive strains and resistant strains of species population. The results indicated that Resistant strains of Laphygma exigua Hubner activity of carboxylesterase was the susceptible strain 1.54 times, and the difference is significant, and the Resistant strains of Laphygma exigua Hubner activity of GST was the susceptible strain 1.86 times, and the difference is also significant. Resistant strains of Laphygma exigua Hubner activity of cytochrome P450 was the susceptible strain 1.45 times, and the difference is significant.6. Resistance realized heritability of Spodoptera exigua to methoxyfenozide, The results indicate that Laphygma exigua Hubner resistance to methoxyfenozide realized heritability as the development rate and the increase of selection pressure pharmacy accelerated, when the selection pressure between 50%-90%, if the Laphygma exigua Hubner resistance to methoxyfenozide increased 10 times, it needs 5.7-17.2 generations. |
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