Mosquitoes (Diptera: Culicidae) from Villages and Forest Areas of Rural Communes in Khanh Hoa and Binh Phuoc Provinces, Vietnam.

This study presents the diversity of mosquitoes collected from communes, endemic with malaria and dengue, located in Khanh Hoa and Binh Phuoc Provinces, Vietnam. A total of 10,288 mosquitoes were collected in the village and forested sites using standard larval dippers, cow-baited traps, ultra-violet light traps, and mechanical aspirators. Mosquito taxa were identified morphologically and species complexes/groups were further characterized molecularly. Five genera of mosquitoes were morphologically identified: Anopheles Meigen (21 species), Aedes Meigen (2 species), Culex Linnaeus (5 species), Mansonia Blanchard sp., and Armigeres Theobald sp. The PCR-based identification methods allowed the distinction of members of Maculatus Group, Funestus Group, and Dirus Complex; and DNA barcodes enabled the further identification of the Barbirostris Complex. Data reported here include the first report of An. saeungae Taai & Harbach and An. wejchoochotei Taai & Harbach from Vietnam, and re-emphasizes the significance of using molecular data in an integrated systematic approach to identify cryptic species and better understand their role in disease transmission.

Quantitative relationships between immature and emergent adult Aedes aegypti (Diptera: Culicidae) populations in water storage container habitats.

Although quantitative surveillance data for immature stages of Aedes aegypti are often used to prioritize containers or specific types of containers for control, the relationship between immature and emergent adult populations under field conditions is largely unknown. We examined the relationships between abundance of III/IV instars and pupae, and emerging adult population for a series of water storage containers in southern Vietnam. A large proportion of III/IV instars failed to progress to adulthood, and the relationships between III/IV instars and adults were poor. Collected IV instars appeared to be nutritionally deprived, although their size and nutrient levels were not reliable indicators of emergence success. Conversely, pupal abundance was a good indicator of emerging adult populations, especially over the ensuing 48-h period. Although there were clear advantages of pupal surveillance over surveillance of III/IV instars for the estimation of adult mosquito productivity, there were practical limitations associated with the enumeration of pupae, and their comparatively low densities may preclude the identification of potentially productive containers.

Householder perspectives and preferences on water storage and use, with reference to dengue, in the Mekong Delta, southern Vietnam.

Community-based perceptions and behaviour around water source preference, household water storage patterns and water use, and householders' knowledge and behaviour with respect to dengue etiology and transmission, were examined in three communes located in the Mekong Delta area in southern Vietnam. Through focus group discussions, most participants identified poorly screened or uncovered water containers (including household water storage containers and other types of artificial containers) as habitats for mosquitoes that transmit dengue viruses, and thereby demonstrated a clear understanding of the links between household water storage practices and the threat of dengue. Our qualitative analyses also revealed broader community-based concerns about the limited availability of water and strong preferences for storage of rainwater based upon perceptions of cost, quality and security of supply. These perceptions are central to shaping householders' responses to water infrastructure projects. The limited availability of water during the dry season and insufficient numbers of water storage containers are over-riding community concerns which provide an important context to understanding community behaviours and responses to public health interventions against dengue. Such concerns are important precursors to selecting the type of intervention.