Culex quinquefasciatus predominance during integrated mosquito surveillance in an urban area of the Brazilian Amazon.

The presence and establishment of Culicidae in urban areas increase the transmissibility of tropical diseases, since some species can participate as vectors of pathogens. Thus, this study aimed to evaluate the indoor and outdoor abundance of immature and adult populations of Culicidae at the urban area of Porto Velho, Rondônia. Mosquitoes were captured using electric aspirators and ovitraps in September and December 2018 in 27 households spread over nine neighborhoods. A total of 2,342 specimens were collected, distributed among five species, of which Culex quinquefasciatus (Say, 1823), Aedes aegypti (Linnaeus, 1762) and Aedes albopictus (Skuse, 1894) were the most abundant. Considering the sum total obtained by both techniques, more mosquitoes were captured indoors than outdoors. However, the GLM estimates for the ovitrap technique showed that immature Ae. aegypti, Ae. albopictus and Cx. quinquefasciatus were significantly more abundant in the outdoors, on average. The opposite result was observed for electrical aspiration, in which Ae. aegypti and Cx. quinquefasciatus adults were more abundant indoors. The average number of winged Ae. albopictus showed no significant difference between indoors and outdoors. Our findings corroborate the data on the abundance and incidence of these three species in other regions of Brazil, highlighting the need for continuous surveillance due to their importance in disease transmission to humans. We also demonstrated that the ovitrap is a sensitive device to monitor Cx. quinquefasciatus larvae and wild species that occasionally frequent urban areas, and thus can be used for surveillance, especially when there are budgetary constraints. Therefore, we emphasize that the combination of techniques, in addition to identifying which species and which stage of development are more frequent inside and outside households, also allows for the implementation of specific and integrated control measures.

Measuring mosquito diversity patterns in an Amazonian terra firme rain forest.

We reanalyzed a dataset consisting of approximately 10,700 crepuscular and night-biting female mosquitoes (Culicidae) collected over 12 mo in the canopy and understorey of primary Amazonian rain forest. We investigate whether vertical habitat stratification and rainfall modified major ecological parameters of this mosquito ensemble, combining descriptive and hypothesis-testing statistics with species richness and diversity metrics in the analyses. A total of 31 species was recorded. Contrary to expectations, the host-seeking mosquito fauna was less diverse in the forest canopy than in the understorey. In particular, species diversity and evenness were higher in understorey samples, whereas species richness estimates were similar in both habitats. Only two out of 12 species tested for vertical stratification were clearly acrodendrophilic, and five preferred understorey habitats. The mosquito fauna was more diverse in the rainy than in the dry season. We propose the hypothesis that female mosquito density and host defensive behavior may promote host seeking in nonpreferred habitats by acrodendrophilic mosquito species. These results may be particularly relevant for understanding the dynamics of Plasmodium malariae/brasilianum and arboviral infections in Amazonian forested landscapes.