RESUMEN
The microbial larvicides Bacillus thuringiensis var. israelensis (Bti) and Bacillus sphaericus (Bs) (Bacillales: Bacillaceae) are well known for their efficacy and safety in mosquito control. In order to assess their potential value in future mosquito control strategies in western Kenya, the current study tested the susceptibility of five populations of Anopheles gambiae complex mosquitoes (Diptera: Culicidae), collected from five diverse ecological sites in this area, to Bti and Bs under laboratory conditions. In each population, bioassays were conducted with eight concentrations of larvicide (Bti/Bs) in four replicates and were repeated on three separate days. Larval mortality was recorded at 24 h or 48 h after the application of larvicide and subjected to probit analysis. A total of 2400 An. gambiae complex larvae from each population were tested for their susceptibility to Bti and Bs. The mean (± standard error of the mean, SEM) lethal concentration values of Bti required to achieve 50% and 95% larval mortality (LC50 and LC95 ) across the five populations were 0.062 (± 0.005) mg/L and 0.797 (± 0.087) mg/L, respectively. Corresponding mean (± SEM) values for Bs were 0.058 (± 0.005) mg/L and 0.451 (± 0.053) mg/L, respectively. Statistical analysis indicated that the five populations of An. gambiae complex mosquitoes tested were fully susceptible to Bti and Bs, and there was no significant variation in susceptibility among the tested populations.
Asunto(s)
Anopheles , Bacillaceae/química , Bacillus thuringiensis/química , Insecticidas , Control de Mosquitos , Control Biológico de Vectores , Animales , Anopheles/crecimiento & desarrollo , Kenia , Larva/crecimiento & desarrolloRESUMEN
The pupal/demographic-survey methodology was evaluated in three coastal areas (one urban, one peri-urban and one rural) of Malindi district, Kenya, in attempts to identify the types of domestic container that are most productive for Aedes aegypti (L.) pupae. The results demonstrated the practicality and consistency of the methodology, as a tool both for identifying and guiding the targeted control of the most productive container habitats, and for determining the mean numbers of pupae/person, as measures of the risk of dengue transmission.Twenty-five types of container were identified indoors and 50 types outdoors. In total, only 4,178 pupae were seen indoors and 795 outdoors. Pupal productivity was dependent on the type, location and volume of the container and the season of the year. Metallic drums and jerricans contributed >70% of the pupae encountered indoors in the wet season whereas, in the rural area, plastic drums contributed 83.7% of all the larvae seen outdoors during the dry season. Container productivity was not consistent during the different surveys. The highest mean numbers of pupae/person (7.61) and of pupae/household (18.12) were recorded in the rural area.