Background: Continuous vector surveillance and sustainable interventions are mandatory in order to prevent anopheline proliferation (or spread to new areas) and interrupt malaria transmission. Anopheline abundance and richness were evaluated in urban and peri-urban malaria foci at a medium-sized city in the Brazilian Amazon, comparing the protected human landing catch technique (PHLC) and alternative sampling methods over different seasonal periods. Additional information was assessed for female feeding behaviour and faunal composition. Methods: Anophelines were sampled bimonthly in four urban and peri-urban sites in the city of Porto Velho, state of Rondônia, Brazil. The average number of captured mosquitoes was compared between an PHLC (gold standard), a tent trap (Gazetrap), and a barrier screen by means of generalized linear mixed models (GLMM), which also included season and environment (peri-urban/urban) as predictors. Results: Overall, 2962 Anopheles individuals belonging to 12 species and one complex were caught; Anopheles darlingi represented 86% of the individuals. More mosquitoes were captured in the peri-urban setting, and the urban setting was more diverse. The model estimates that significantly more anophelines were collected by PHLC than by the Screen method, and Gazetrap captured fewer individuals. However, the Screen technique yielded more blood-engorged females. The peak hours of biting activity were from 6 to 7 p.m. in urban areas and from 7 to 8 p.m. in peri-urban areas. Conclusions: Although peri-urban settings presented a greater abundance of anophelines, Shannon and Simpson diversities were higher in urban sites. Each technique proved to be useful, depending on the purpose: PHLC was more effective in capturing the highest anopheline densities, Gazetrap caught the greatest number of species, and the barrier screen technique captured more engorged individuals. There was no seasonal effect on Anopheles assemblage structure; however, a more diverse fauna was caught in the transitional season. Biting activity was more intense from 6 to 8 p.m., with a predominance of An. darlingi.
Mosquitoes are vectors of many pathogens, including viruses, protozoans, and helminths, spreading these pathogens to humans as well as to wild and domestic animals. As the identification of species and the biological characterization of mosquito vectors are cornerstones for understanding patterns of disease transmission, and the design of control strategies, we conducted a literature review on the current use of noninvasive and nondestructive techniques for pathogen detection in mosquitoes, highlighting the importance of their taxonomic status and systematics, and some gaps in the knowledge of their vectorial capacity. Here, we summarized the alternative techniques for pathogen detection in mosquitoes based on both laboratory and field studies. Parasite infection and dissemination by mosquitoes can also be obtained via analyses of saliva- and excreta-based techniques or of the whole mosquito body, using a near-infrared spectrometry (NIRS) approach. Further research should be encouraged to seek strategies for detecting target pathogens while preserving mosquito morphology, especially in biodiversity hotspot regions, thus enabling the discovery of cryptic or new species, and the determination of more accurate taxonomic, parasitological, and epidemiological patterns.
1 January 2025 in Revista da Sociedade Brasileira de Medicina Tropical
Background: Triatomine recognition by the public is an important factor in Chagas disease (CD) prevention campaigns. Citizen surveillance has been demonstrated as an effective alternative strategy, increasing the possibility of monitoring vector populations on a broad geographic scale. Thus, our study aimed to explore a database built from pictorial/video records and specimens sent through citizen participation, identify the main groups confused with triatomines, and systematize the data on insect diversity.
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.
Results from previous inventory studies on the Brazilian culicids may have indicated sampling gaps in the Amazon ecosystem. In this study, we inventoried the diversity of mosquitoes in the state of Rondônia using databases (speciesLink, Brazilian Biodiversity Information System, and Global Biodiversity Information Facility) and articles published over an 86-year period (Web of Science, Scopus, Google Scholar) to contribute to species richness knowledge and the number of records per municipality, highlighting species that act as disease vectors. The survey recorded 24 genera and 149 species of the Culicidae family in Rondônia. The genus Anopheles Meigen, 1818 had the highest species richness (36 species), followed by Culex Linnaeus, 1758 (18 species) and Sabethes Robineau-Desvoidy, 1827 (14 species); however, ten genera were represented by only one species. The geographic coverage of culicid records was limited, with only 16 of the 52 municipalities in the state exhibiting occurrences. Most of the species recorded in scientific articles were sampled from rural environments (n = 70); studies conducted in urban areas recorded 20 species from four genera. The Fiocruz Collections substantially contributed to the overview of Amazonian diversity. In conclusion, our findings reflect the epidemiological importance and inherent diversity of the taxa, emphasizing the need to increase sampling efforts in the Amazon biome to include the culicid fauna of various environments and the phytogeographic domains that constitute it.