Lethal Ovitraps Research Articles

Community Participation and Appropriate Technologies for Dengue Vector Control at Transmission Foci in Thailand

A community-based dengue vector control trial was conducted at transmission foci in Plaeng Yao District, Chachoengsao Province, eastern Thailand. Implementation was done by the local community in collaboration with local administration, public health, and school authorities. Our cost-effective approaches combined a source reduction campaign with appropriate vector control technologies applied within the foci (within 100 m around the foci) and also within schools attended by children from the treated areas. Vector management measures by local government included cleanup campaigns before the rainy season followed by a routine garbage pickup during the rainy season. Locally made screen covers for water jars, a combination of local Bacillus thuringiensis subsp. israelensis and Mesocyclops thermocyclopoides (copepod), and locally made lethal ovitraps were appropriate technologies used by the community in this campaign. The success of our intervention was evidenced by the significant reduction of dengue vectors and dengue hemorrhagic fever cases in treated areas compared with untreated areas.

Field evaluation of a lethal ovitrap for the control of Aedes aegypti (Diptera: Culicidae) in Thailand.

In 1999 and 2000 we evaluated a lethal ovitrap (LO) for the control of Aedes aegypti (L.) in three villages in Ratchaburi Province, Thailand. Two blocks of 50 houses (a minimum of 250 m apart) served as treatment and control sites in each village, with each house in the treatment area receiving 10 LOs. Thirty houses in the center of each treatment and control block were selected as sampling sites, with larval and adult mosquito sampling initiated when LOs were placed. Sampling was conducted weekly in 10 of the 30 houses at each site, with each block of 10 houses sampled every third week. Sampling continued for 30 wk. Efficacy of the LO was evaluated by determining number of containers with larvae and/or pupae per house and number of adult mosquitoes collected inside each house. In 1999, the LO had a negligible impact on all measures of Ae. aegypti abundance that were assessed; however, fungal contamination of insecticide-impregnated strips may have been responsible for the low efficacy. In 2000, significant suppression was achieved based on changes in multiple entomologic criteria (containers with larvae, containers with pupae, and number of adult Ae. aegypti); however, control was not absolute and neither immature nor adult Ae. aegypti were ever eliminated completely. We conclude that the LO can reduce adult Ae. aegypti populations in Thailand; however, efficacy of the LO is lower than desired due primarily to the high number of alternative oviposition sites. LO efficacy may be improved when used as part of an integrated control program that places emphasis on reduction of adjacent larval habitats. Further studies are required to assess this issue.