Seasons and socio-cultural practices affecting Aedes mosquito larvae in southern Thailand

The aims of this study are to examine the effects of (1) socio-cultural practices of using different types of water storage containers, and (2) seasons, on the numbers of Aedes aegypti and Aedes albopictus larvae in the five sub-districts of Lansaka district. We randomly selected 20 houses per sub-district per month, with a total of 600 households, and collected Aedes mosquito larvae from different types of containers (indoor/outdoor, natural/artificial, dark/light coloured, and with/without lids) during both the dry (March-May 2015) and wet (October-December 2015) seasons. Ae. aegypti and Ae. albopictus larvae found in each container were identified and counted. The larval indices (i.e., house index (HI), container index (CI), and Breteau index (BI)) were calculated for each sub-district, and for each season. Our results showed that socio-cultural practices of using different types of containers differed between sub-districts and seasons. Ae. albopictus larval indices were higher than Ae. aegypti larval indices in both seasons. Ae. albopictus larval indices were higher in the wet season than in the dry season; the opposite results were observed for Ae. aegypti. Ae. albopictus larvae were more commonly found in outdoor containers in both seasons, but were found to be more in light coloured and without lid containers during the dry season, whereas Ae. aegypti larvae were more often found in indoor containers in both seasons, but are found more in light coloured containers in the dry season. There were positive correlations between container numbers and mosquito larvae numbers in all sub-districts. These results indicate that seasons and water container types have strong effects on the breeding of Aedes mosquito larvae. This knowledge could be used to obtain a better understanding on how to take initiatives that could promote the prevention and control of dengue vectors.