| Summary: | 碩士 === 國立臺灣大學 === 流行病學與預防醫學研究所 === 101 === The global incidence of dengue has significantly increased in recent years and has become an important issue in public health. The current vector control strategy in Taiwan is source reduction. Chemical pesticides are applied only when dengue case appears. Even so, the frequent use of pesticides over a long period of time has led to development of resistance in vector mosquitoes. Therefore, a vector control method with eco-friendly approach is in demand. In 2010, NTU-CPH laboratory has identified numerous species of Mesocyclops spp. with highly predating efficiency on mosquito larvae. In this study, we further applied these local species of copepods in dengue risk areas to evaluate their performance as agents for bio-control. To start with, we collected freshwater copepods in Southern Taiwan where indigenous dengue cases frequently occur, including Chiayi (sample number, N=144), Tainan (N=109), Kaohsiung (N=179), and Pingtung (N=262). Second, we identified the species of copepods by morphology and molecular analysis. The collected freshwater copepods were recognized as Mesocyclops spp., Thermocyclops spp., Metacyclops spp., Eucyclops spp. and Cyclops spp.. Third, we investigated the chemical pesticide tolerance of copepods, and the result showed that copepods were with lower sensitivity than mosquitoes when treated with the currently used insecticides. Next, to evaluate the potential and feasibility of using Taiwanese freshwater Mesocyclops spp. as a bio-control agent of dengue virus, we cooperated with the Department of Health, Kaohsiung City Government. Inform consents were signed by the local public health centers and residents before setting sentinel sites in flooded basements in Kaohsiung (N=165). 25% of the trial sites were chosen randomly (N=42) at the following step. Sites were excluded if they were dry or too difficult to access. Eventually, 24 trial sites were targeted for long-term surveillance. After more than one year of observation (from March 2012 to July 2013), our results showed that the positive rates of larvae have decreased from 65.0% to 0, and the survival rates of copepods were 45.3% to 60.0% in clean flooded basements. In conclusion, this study has proved that copepods were not only able to be maintained and survived in the flooded basements but have functioned on decreasing the number of Aedes larvae. Our findings suggested that Taiwanese freshwater Mesocyclops could be provided as a biological agent for dengue larvae control in Kaohsiung City.
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