Efficacy and persistence of Bacillus thuringiensis svar. israelensis (Bti) and pyriproxyfen-based products in artificial breeding sites colonized with susceptible or Bti-exposed Aedes aegypti larvae

Aedes aegypti control requires integrated actions adapted to local conditions. In endemic countries, breeding sites in the dwellings are important mosquito sources that should be controlled using safe larvicides. The major goal of this study was to evaluate the efficacy and persistence of three Bti- and one pyriproxyfen-based products toward Ae. aegypti larvae from a reference colony and to a colony previously exposed to Bti (RecBti). For this purpose, labeled doses of products were tested in ovitraps (OVT-2L), water containers (WCN-50L) and roof water drains (RWD-5L) that were colonized weekly with 100 larvae and kept under semifield conditions. Persistence was recorded for a maximum period of 12 weeks. All products provided residual activity (mortality >= 80%) for 12 weeks in OVTs and RWDs. In WCNs, persistence was shorter between six and nine weeks for Bti- and pyriproxyfen-based products. The performance of Bti products for RecBti larvae was similar to larvae from the reference colony, reinforcing the low risk of resistance selection to that compound. Products were effective to prevent Aedes larvae breeding with a persistence of 12 weeks in most breeding sites. Data support their effectiveness to protect such sites as part of a broader set of mosquito control practices.