Winter Refuge for Aedes aegypti and Ae. albopictus Mosquitoes in Hanoi during Winter |
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Authors: | Takashi Tsunoda Tran Chi Cuong Tran Duc Dong Nguyen Thi Yen Nguyen Hoang Le Tran Vu Phong Noboru Minakawa |
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Institution: | 1. Department of Vector Ecology and Environment, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan.; 2. Department of Medical Entomology and Zoology, National Institute of Hygiene and Epidemiology, Hanoi, Vietnam.; Kansas State University, United States of America, |
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Abstract: | Dengue occurs throughout the year in Hanoi, Vietnam, despite winter low temperatures <10°C. During July 2010 to March 2012, we surveyed monthly for Aedes larvae and pupae in 120 houses in 8 Hanoi districts. Aedes albopictus preferred discarded containers in summer and pupal density drastically decreased in winter. Aedes aegypti preferred concrete tanks and this preference increased in winter. Even in winter, the lowest water temperature found in concrete tanks was >14°C, exceeding the developmental zero point of Ae. aegypti. Although jars, drums and concrete tanks were the dominant containers previously (1994–97) in Hanoi, currently the percentage of residences with concrete tanks was still high while jars and drums were quite low. Our study showed that concrete tanks with broken lids allowing mosquitoes access were important winter refuge for Ae. aegypti. We also indicate a concern about concrete tanks serving as foci for Ae. aegypti to expand their distribution in cooler regions. |
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