Container types and water qualities affecting on number of Aedes larvae in Trang province, Thailand

Abstract

This study investigated the effects of container types, and water qualities on numbers of Aedes mosquito larvae. Mosquito larvae were collected from nine sub-districts with ten households per sub-district in Trang province in March 2017 (i.e. Nongtrut, Natoming, Khuanpring, Bangrak, Khoklo, Banpho, Namphud, Tubtheang, and Nayongtai districts). We collected mosquito larvae in water containers using fishnets (0.55 mm mesh size) and preserved the mosquito larvae in 70% ethanol in the laboratory. We grouped containers in three groups (jar and tank, dustbins and others such as areca nut preservation jars and animal food bowls). We recorded water qualities in each container (presence of vegetation and algae, water level, odour, turbidity, temperature and pH). We identified the mosquito larvae to genus level and counted the numbers. We calculated the mosquito larvae indices (House index (HI), (Breteau index (BI), and Container index (CI)). For this study, we focused only on Aedes species; other species were discarded. We observed that container types, presence of algae in water, water odour, temperature and pH did not have effects on Aedes species larval numbers. Larval numbers were higher in clear and without vegetation water than in turbid and vegetative water, respectively. In addition, 50-75% of water level in the containers was the most preferred level for the Aedes species. Among nine sub-districts, Khoklo, Banpho, and Tubthiang had the highest HI, and Tubthiang had the highest BI and CI.