ABSTRACT
Background: Two species, Aedes aegypti and Aedes albopictus are the main intermediate vectors of transmission of the dengue viruses in Vietnam. Insecticide applications by different methods that may help interrupt the spread of dengue outbreaks. Many different groups of insecticides have been used for dengue vector control. Some recent studies revealed that Aedes vectors obscuring their resistance to insecticides at different levels. Therefore, a new insecticide formula is required for effective dengue vectors control. Objective: To evaluate the efficacy of Bistar 80SC by residual application in suppression of Aedes species in a northern province of Vietnam. Subject and methods: Bistar 80 SC with a component of Bifenthrin 80g/L was evaluated by residual application in suppression of 2 Aedes species in vitro and in an intervention commune of Hien Giang, Thuong Tin district and a control commune of Van Mo, Ha Dong town, Ha Tay province from March, 2004 to June, 2004. Results: WHO Bifenthrin paper test kit was effective at the concentration of 37.5mg/m2 and over with Aedes aegypti vectors ranged from 80% to 100% mortality in the North, In other words, Aedes vector remains susceptible to Bifenthrin in the region. The mortality on wood surface after 60 minutes of exposure to Bistar 80SC at concentrations of 25mg/m2 by using residual application was higher than those on brick walls. Up to 100% Aedes aegypti was killed after 60 minutes in exposure and remains in effect until the end of the third months and one month with Aedes albopictus. No side effects, to the sprayer and humans, livestock and environment caused by Bistar 80SC were reported in the intervention area. Conclusion: Bistar 80SC is suggested as a nominated alternative to effectively control the dengue outbreak by residual application.
ABSTRACT
Background: Dengue fever remains a major public health problem in Vietnam. It was transmitted through two main Aedes species, namely Aedes aegypti and Aedes albopictus in which Aedes aegypti played the predominant role in transmitting the dengue viruses (accounted for 94% of the Aedes genus).Different groups of insecticides have been widely used in the community. As a consequence, it increased the resistance level of Aedes vectors to the insecticides. Therefore, a new synthesized insecticide was required for future control and prevention of dengue epidemics. \r\n', u'Objectives: To evaluate the efficacy of Cynoff 25 ULV in suppressing Aedes species in Vietnam. \r\n', u'Subjects and methods: The study was conducted in the entomology laboratory and in the fields of Ha Tay province. ULV spraying was implemented in Hiengiang commune, Thuongtin district, in comparison with a control area, Van Mo commune in Ha Dong town.\r\n', u'Results and conclusions: : Cynoff 25 ULV had a high efficacy that kills over 90% of 2 dengue vector species, namely Aedes aegypti and Aedes albopicctus after 24 hours exposure at the distance of 30 meters from the brass nozzle of a STIHL SR 400 sprayer. In the field trials, Cynoff 25 ULV also had high efficacy in killing Aedes species, e.g. 100% of Aedes species were killed after spraying and the effects lasted for 3 months for Aedes aegypti and one month for Aedes albopictus species. The insecticide had no side-effects or any other adverse effects to humans, livestock and the environment in the intervention areas. \r\n', u'