Dispersion and oviposition of Aedes albopictus in a Brazilian slum: Initial evidence of Asian tiger mosquito domiciliation in urban environments

Abstract

Aedes albopictus, originally considered as a secondary vector for arbovirus transmission, especially in areas where this species co-exist with Aedes aegypti, has been described in most regions of the world. Dispersion and domiciliation of Ae. albopictus in a complex of densely urbanized slums in Rio de Janeiro, Southeastern Brazil, was evidenced. In this study, we tested the hypotheses that 1) Ae. albopictus distribution in urban slums is negatively related to distance from vegetation, and 2) these vectors have taken on a domestic life style with a portion of the population feeding, ovipositing, and resting indoors. To do this, we developed an integrated surveillance proposal, aiming to detect the presence and abundance of Aedes mosquitoes. The study, based on a febrile syndrome surveillance system in a cohort of infants living in the slum complex, was performed on a weekly basis between February 2014 and April 2017. A total of 8,418 adult mosquitoes (3,052 Ae. aegypti, 44 Ae. albopictus, 16 Ae. scapularis, 4 Ae. fluviatilis and 5,302 Culex quinquefasciatus) were collected by direct aspiration and 46,047 Aedes spp. eggs were collected by oviposition traps. The Asian tiger mosquito, Ae. albopictus, was aspirated in its adult form (n = 44), and immature forms of this species (n = 12) were identified from the eggs collected by the ovitraps. In most collection sites, co-occurrence of Ae. aegypti and Ae. albopictus was observed. Key-sites, such as junkyards, thrift stores, factories, tire repair shops and garages, had the higher abundance of Ae. albopictus, followed by schools and households. We collected Ae. albopictus at up to 400 meters to the nearest vegetation cover. The log transformed (n+1) number of females Ae. albopictus captured at each collection point was inversely related to the distance to the nearest vegetation border. These results show that Ae. albopictus, a competent vector for important arboviruses and more commonly found in areas with higher vegetation coverage, is present and spread in neglected and densely urbanized areas, being collected at a long distance from the typical encounter areas for this species. Besides, as Ae. albopictus can easily move between sylvatic and urban environment, the entomological monitoring of Ae. albopictus should be an integral part of mosquito surveillance and control. Finally, key-sites, characterized by high human influx and presence of potential Aedes breeding sites, should be included in entomological monitoring.

Natural Infection of Aedes aegypti by Chikungunya and Dengue type 2 Virus in a Transition Area of North-Northeast Brazil

“…As this study was carried out in residences located in urban neighborhoods, few specimens were collected. However, it is necessary to monitor their density, as this species have been showing changes in behavior and were reported close to urban areas [64,65], including studies conducted in the municipality of Caxias, Maranhão [35,36].…”

A populational-based birth cohort study in a low-income urban area in Rio de Janeiro, Brazil: implementation and description of the characteristics of the study

“…Ae. albopictus, a competent vector for important arboviruses and more commonly found in areas with higher vegetation coverage, was present in this low-income urbanized area 32 . Moreover, Zika virus was detected in April 2015 in engorged Ae.…”

Silent circulation of dengue virus in Aedes albopictus (Diptera: Culicidae) resulting from natural vertical transmission

“…albopictus when compared to Ae. aegypti 24,25,48 which maintains DENV circulation in areas with high concentrations of human beings and houses 49,50 . This may have increased the chances of finding viral circulation in Ae.…”