| Summary: | 碩士 === 國立中興大學 === 昆蟲學系所 === 96 === The objective of this study is to study the resistance development of Aedes aegypti collected from Kaohsiung in 2006 and Tainan in 2007 to frequently used pyrethroid insecticides, and investigate the possible mechanisms involved in resistance development. The bioassay results showed that the larvae collected from different areas of Kaohsiung have developed more than 10-fold resistance to permethrin, cypermethrin, lambda-cyhalothrin, deltamethrin and fenvalerate. In particular, the larvae of Chianjen strain had developed 5783-fold resistance to fenvalerate, which is even higher than 3127-fold of Per-R37 strain. Similar results were observed on the larvae collected from Guosing, Yuhuang and Dafu areas of Tainan. The larvae of these three strains had developed more than 20-fold resistance to tested insecticides, and the adults had showed less than 31% of mortality after 24-hr exposure to insecticides-impregnated papers. These results demonstrated that some field strains of Aedes aegypti have developed relatively high resistance to various pyrethroid insecticides, especially fenvalerate, and therefore these insecticides are not recommended to control the vectors of dengue fever in Kaohsiung and Tainan. Based on synergist study, the resistance of Chianjen and Per-R42 strains of Aedes aegypti to permethrin, cypermethrin and fenvalerate, is correlated to the degradation of monooxygenase. However the specific activity of monooxygenase in Per-R is only 1.9-fold higher than the Bora Bora susceptible strain. The analysis of kdr point mutation had shown that the frequency of point mutation was 100% in Per-R42 strains and 6.3% in Bora Bora strain. These results indicate the monooxygenase and target site insensitivity might play an important role in resistance developed of Per-R strain to pyrethroids insecticides.
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