Alphacypermethrin (Fendona) and lambda-cyhalothrin (Icon) were evaluated against sentinel bloodfed adults and 4th-instar larvae of Aedes aegypti in a housing estate in Malaysia. The impact of both pyrethroids on field populations of Ae. aegypti and Aedes albopictus were monitored weekly using oviposition trap samples. Both alphacypermethrin and lambda-cyhalothrin showed adulticidal and larvicidal effects.
Partial replacement of resident Aedes aegypti mosquitoes with introduced mosquitoes carrying certain strains of inherited Wolbachia symbionts can result in transmission blocking of dengue and other viruses of public health importance. Wolbachia strain wAlbB is an effective transmission blocker and stable at high temperatures, making it particularly suitable for hot tropical climates. Following trial field releases in Malaysia, releases using wAlbB Ae. aegypti have become operationalized by the Malaysian health authorities. We report here on an average reduction in dengue fever of 62.4% (confidence intervals 50-71%) in 20 releases sites when compared to 76 control sites in high-rise residential areas. Importantly the level of dengue reduction increased with Wolbachia frequency, with 75.8% reduction (61-87%) estimated at 100% Wolbachia frequency. These findings indicate large impacts of wAlbB Wolbachia invasions on dengue fever incidence in an operational setting, with incidence expected to further decrease as wider areas are invaded.