RESUMEN
The present study aimed to assess mosquito species diversity, distribution, and ecological preferences in the Covè, Ouinhi, and Zangnanado communes, Southern Benin. Such information is critical to understand mosquito bio-ecology and to focus control efforts in high-risk areas for vector-borne diseases. Mosquito collections occurred quarterly in 60 clusters between June 2020 and April 2021, using human landing catches. In addition to the seasonal mosquito abundance, Shannon's diversity, Simpson, and Pielou's equitability indices were also evaluated to assess mosquito diversity. Ecological niche models were developed with MaxEnt using environmental variables to assess species distribution. Overall, mosquito density was higher in the wet season than in the dry season in all communes. A significantly higher Shannon's diversity index was also observed in the wet season than in the dry seasons in all communes (p < 0.05). Habitat suitability of An. gambiae s.s., An. coluzzii, Cx. quinquefasciatus and Ma. africana was highly influenced by slope, isothermality, site aspect, elevation, and precipitation seasonality in both wet and dry seasons. Overall, depending on the season, the ecological preferences of the four main mosquito species were variable across study communes. This emphasizes the impact of environmental conditions on mosquito species distribution. Moreover, mosquito populations were found to be more diverse in the wet season compared to the dry season.
Asunto(s)
Biodiversidad , Ecosistema , Malaria , Mosquitos Vectores , Estaciones del Año , Animales , Benin , Mosquitos Vectores/fisiología , Malaria/transmisión , Culicidae/clasificación , Culicidae/fisiología , Humanos , Anopheles/fisiología , Anopheles/clasificaciónRESUMEN
BACKGROUND: Long-lasting insecticidal nets (LLINs) may have different impacts on distinct mosquito vector species. We assessed the efficacy of pyrethroid-pyriproxyfen and pyrethroid-chlorfenapyr LLINs on the density of Anopheles gambiae s.s. and An. coluzzii compared to pyrethroid-only nets in a three-arm cluster randomised control trial in Benin. METHODS: Indoor and outdoor collections of adult mosquitoes took place in 60 clusters using human landing catches at baseline and every 3 months for 2 years. After morphological identification, around 15% of randomly selected samples of An. gambiae s.l. were dissected to determine parity, species (using PCR). RESULTS: Overall, a total of 46,613 mosquito specimens were collected at baseline and 259,250 in the eight quarterly collections post-net distribution. Post-net distribution, approximately 70% of the specimens of An. gambiae s.l. speciated were An. coluzzii, while the rest were mostly composed of An. gambiae s.s. with a small proportion (< 1%) of hybrids (An. gambiae/coluzzii). There was no evidence of a significant reduction in vector density indoors in either primary vector species [An. coluzzii: DR (density ratio) = 0.62 (95% CI 0.21-1.77), p = 0.3683 for the pyrethroid-pyriproxyfen LLIN and DR = 0.56 (95% CI 0.19-1.62), p = 0.2866 for the pyrethroid-chlorfenapyr LLIN, An. gambiae s.s.: DR = 0.52 (95% CI 0.18-1.46), p = 0.2192 for the pyrethroid-pyriproxyfen LLIN and DR = 0.53 (95% CI 0.19-1.46), p = 0.2222 for the pyrethroid-chlorfenapyr]. The same trend was observed outdoors. Parity rates of An. gambiae s.l. were also similar across study arms. CONCLUSIONS: Compared with pyrethroid-only LLINs, pyrethroid-chlorfenapyr LLINs and pyrethroid-pyriproxyfen LLINs performed similarly against the two primary mosquito species An. gambiae s.s. and An. coluzzii in Benin.