| 論文英文摘要 |
In recent years, Cnaphalocrocis medinalis (Lepidoptera: Pyralidae) become an important pest on the rice of second phase in Taiwan. Application of insecticides was the main method to control this insect, but the resistance to various kinds of insecticides has been documented in Taiwan and other countries. This study investigated the resistance of C. medinalis from Changjhih and Houbi to eight insecticides. The results showed that both populations developed resistance to cyhalothrin, and the Changjhih population showed additional resistance to cartap. The synergist test was used to determine whether detoxification enzymes were involved in the metabolic resistance to cyhalothrin and cartap. When C. medinalis of Changjhih and Houbi populations were treated with cyhalothrin and three synergists individually, these two populations synergistic ratio of 285 and 606.8 for piperonyl butoxide (PBO), 1.74 and 5.4 for Diethyl maleate (DEM), 2.21 and 7.53 for Triphenyl phosphate (TPP), respectively. In addition, synergism of cartap and PBO was observed in Changzhi population, and the synergistic ratio was 3.64. Further analysis about detoxification enzymes activity treated with cyhalothrin or cartap at different concentrations for
C. medinalis, biochemical assay showed cytochrome P450 (P450) activity increased significantly for Changzhi population after exposure 1 µg/ml cyhalothrin, however, the degree of Esterase (EST) and Glutathione-S- transferase (GST) activity increased at higher concentration of cyhalothrin. Besides, elevation of CYP450 activity of Houbi population with the concentration increasing, but EST activity was significantly reduced. The result showed P450 and EST activity significantly decreased in Houbi population after exposure to cartap. Above results concluded all three kinds of detoxification enzymes are involved in metabolism of cyhalothrin for C. medinalis, and cytochrome P450 is the major detoxification enzyme in the metabolism of cyhalothrin and Cartap. Overall results showes degrees of difference of cyhalothrin resistance from two poplution might appear correlation with synergistic test by the PBO. |