Fauna and Virological Investigation of Mosquitoes in Urban Parks in Sã;o Paulo, Brazil.

The mosquito fauna in urban parks in the city of São Paulo, Brazil, was investigated and compared for richness and diversity, and the abundance of each species was associated with climatic variables. Simultaneously, a virological investigation was performed to test the presence of Flavivirus and Alphavirus. Aspirations of adult mosquitoes were conducted in 3 urban parks for 3 consecutive weeks of each season between October 2018 and January 2020. A total of 2,388 mosquitoes were identified, with Culex quinquefasciatus, Cx. nigripalpus, and Aedes aegypti being the most abundant species. Mosquito assemblages showed similar richness and diversity, showing variability in individual results. Temperatures and Ae. aegypti abundance correlated significantly in one of the parks investigated herein. Urban parks represent areas of shelter and refuge for both anthropophilic and opportunistic species, such as Cx. quinquefasciatus and Ae. aegypti, as well as species that still need moderately preserved environments to develop.

First Report of Wenzhou sobemo-like virus 4 in Aedes albopictus (Diptera: Culicidae) in Latin America.

Insect-specific viruses (ISVs) are viruses that replicate exclusively in arthropod cells. Many ISVs have been studied in mosquitoes as many of them act as vectors for human etiological agents, such as arboviruses. Aedes (Stegomyia) albopictus is an important potential vector of several arboviruses in Brazil, such as dengue (DENV), Zika (ZIKV) and chikungunya (CHIKV). The development of next-generation sequencing metagenomics has enabled the discovery and characterization of new ISVs. Ae. albopictus eggs were collected using oviposition traps placed in two urban parks in the city of São Paulo, Brazil. The Aedes albopictus females were divided into pools and the genetic material was extracted and processed for sequencing by metagenomics. Complete genomes of ISV Wenzhou sobemo-like virus 4 (WSLV4) were obtained in three of the four pools tested. This is the first detection of ISV WSLV4 in Ae. albopictus females in Latin America. Further studies on ISVs in Ae. albopictus are needed to better understand the role of this species in the dynamics of arbovirus transmission in the Americas.

Entomological Survey of the Mosquitoes in an Area of Ecological TOurism in the Brazilian Amazon Basin.

Mosquitoes have a great epidemiological importance, since females of several species transmit etiological agents of human diseases, such as malaria and arboviruses. In Brazil, the state of Acre has been highlighted in recent years for its high incidence of diseases of relevance to public health, such as malaria, dengue, and leishmaniases, whose etiological agents are transmitted by insect vectors, including mosquitoes. Nevertheless, few studies have been carried out on the mosquito fauna in Acre State; this study aims to identify the culicid fauna of an ecological tourism area of the municipality of Xapuri, Acre State, Brazilian Amazon. Mosquito collections were carried out monthly at the Seringal Cachoeira settlement, between April 2014 and March 2015 using 6 automatic Centers for Disease Control and Prevention light traps, one in each ecotope. During the study period, 1,021 specimens belonging to the genera Aedeomyia, Aedes, Anopheles, Coquillettidia, Culex, Mansonia, Orthopodomyia, Psorophora, Trichoprosopon, and Uranotaenia were collected. The genus Culex was predominant, Culex (Culex) quinquefasciatus being the most frequent species, followed by Cx. (Melanoconion) gnomatos. The importance of these findings is discussed.

Assessing the effects of Aedes aegypti kdr mutations on pyrethroid resistance and its fitness cost.

Pyrethroids are the most used insecticide class worldwide. They target the voltage gated sodium channel (NaV), inducing the knockdown effect. In Aedes aegypti, the main dengue vector, the AaNaV substitutions Val1016Ile and Phe1534Cys are the most important knockdown resistance (kdr) mutations. We evaluated the fitness cost of these kdr mutations related to distinct aspects of development and reproduction, in the absence of any other major resistance mechanism. To accomplish this, we initially set up 68 crosses with mosquitoes from a natural population. Allele-specific PCR revealed that one couple, the one originating the CIT-32 strain, had both parents homozygous for both kdr mutations. However, this pyrethroid resistant strain also presented high levels of detoxifying enzymes, which synergistically account for resistance, as revealed by biological and biochemical assays. Therefore, we carried out backcrosses between CIT-32 and Rockefeller (an insecticide susceptible strain) for eight generations in order to bring the kdr mutation into a susceptible genetic background. This new strain, named Rock-kdr, was highly resistant to pyrethroid and presented reduced alteration of detoxifying activity. Fitness of the Rock-kdr was then evaluated in comparison with Rockefeller. In this strain, larval development took longer, adults had an increased locomotor activity, fewer females laid eggs, and produced a lower number of eggs. Under an inter-strain competition scenario, the Rock-kdr larvae developed even slower. Moreover, when Rockefeller and Rock-kdr were reared together in population cage experiments during 15 generations in absence of insecticide, the mutant allele decreased in frequency. These results strongly suggest that the Ae. aegypti kdr mutations have a high fitness cost. Therefore, enhanced surveillance for resistance should be priority in localities where the kdr mutation is found before new adaptive alleles can be selected for diminishing the kdr deleterious effects.

Dengue infection increases the locomotor activity of Aedes aegypti females.

BACKGROUND: Aedes aegypti is the main vector of the virus causing Dengue fever, a disease that has increased dramatically in importance in recent decades, affecting many tropical and sub-tropical areas of the globe. It is known that viruses and other parasites can potentially alter vector behavior. We investigated whether infection with Dengue virus modifies the behavior of Aedes aegypti females with respect to their activity level. METHODS/PRINCIPAL FINDINGS: We carried out intrathoracic Dengue 2 virus (DENV-2) infections in Aedes aegypti females and recorded their locomotor activity behavior. We observed an increase of up to ∼50% in the activity of infected mosquitoes compared to the uninfected controls. CONCLUSIONS: Dengue infection alters mosquito locomotor activity behavior. We speculate that the higher levels of activity observed in infected Aedes aegypti females might involve the circadian clock. Further studies are needed to assess whether this behavioral change could have implications for the dynamics of Dengue virus transmission.