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  • 學位論文

於高雄以中劍水蚤防治登革熱病媒蚊幼蟲之田間試驗

Field trials using Mesocyclops spp. to control dengue mosquito larvae in Kaohsiung City

指導教授 : 蔡坤憲
共同指導教授 : 方啟泰(Chi-Tai Fang)

摘要


登革熱全球發生率逐年升高,是一個重要的公共衛生議題。目前台灣病媒蚊控制策略為孳生源清除及疫情時緊急噴灑化學藥劑,然而長期密集使用化學藥劑,已使得蚊蟲產生嚴重抗藥性,因此尋求一個環境友善的登革控制策略是相當迫切需要的。從民國99年度以來,國立台灣大學公共衛生學院蟲媒傳染病實驗室已確認臺灣本土具有多種高捕食性橈足類中劍水蚤,本研究規劃將南臺灣採集到的劍水蚤實際運用於高雄的登革熱流行區,並評估其生物防治功效。首先,在埃及斑蚊分布的嘉義、台南、高雄、屏東四縣市進行劍水蚤之採集,採集樣點數分別為144、109、 179、262個,接著利用分子及型態鑑定進行物種分析,鑑定結果發現南台灣具中劍水蚤屬 (Mesocyclops spp.)、溫劍水蚤屬 (Thermocyclops spp.)、后劍水蚤屬 (Metacyclops spp.)、真劍水蚤屬 (Eucyclops spp.)、劍水蚤屬 (Cyclops spp.) 之劍水蚤,而中劍水蚤屬以北碚中劍水蚤 (M. pehpeiensis)、鄔氏中劍水蚤(M. woutersi)、奧貢中劍水蚤 (M. ogunnus) 及糙角中劍水蚤 (M. aspericornis) 最多。為了解現行殺蟲劑對於劍水蚤的影響,進行蘇力菌 (Bacillus thuringiensis israelensis,B.t.i.)、陶斯松 (Chlopyrifos)、美賜平 (Methoprene)、百滅寧 (Permethrin)、賽酚寧 (Cyphenothrin) 等五種市售殺蟲劑的感受性分析,發現斑蚊幼蟲對於殺蟲劑具高敏感性,但劍水蚤則較不受影響,比較五種殺蟲劑發現陶斯松毒殺性最高 (劍水蚤和埃及斑蚊幼蟲的半數致死濃度分別為LC50=6.2*10-4ppm和LC50=5.2*10-9ppm),對美賜平最不敏感 (劍水蚤和埃及斑蚊幼蟲的半數致死濃度分別為LC50=1.5*101 ppm和LC50=1.4*100ppm)。進一步評估劍水蚤做為生物防治可行性,在高雄積水地下室進行以劍水蚤防治登革熱病媒蚊幼蟲之田間試驗,透過研究計畫說明和取得高雄衛生局同意後,在高雄陽光家園完成三種高捕食性的中劍水蚤的大量培養,挑選單純施放中劍水蚤之列管積水地下室 (N=165),隨機取樣25%做為長期追蹤試驗點 (N=42),於試驗點以傾倒法施放中劍水蚤,定期採樣監測評估,追蹤一年多後,發現中劍水蚤可長期存活於大面積水質清澈之積水地下室,中劍水蚤成功繁殖率約45.3-60.0%,斑蚊幼蟲陽性率從65% (101年3月) 降至0 (102年7月)。綜合本研究成果發現,南台灣具有高捕食性劍水蚤物種,且劍水蚤對於殺蟲劑較不敏感,並具有顯著降低斑蚊幼蟲族群之登革熱防治功效。

並列摘要


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.

參考文獻


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