Mosquitoes (Diptera, Culicidae) in avian malaria transmission area: identification of potential vector species of Culex genus

Author(s)

Roseli França Simões

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Faculdade de Medicina (FM/SBD)
• Defense date: 2021-05-07

Examining board members

Karin Kirchgatter; Fabio de Almeida; Tamara Nunes de Lima Camara; Juliana Telles de Deus

• Advisor: Karin Kirchgatter

Abstract

Avian malaria parasites are widespread parasites transmitted by Culicidae insects belonging to different genera. Even though several studies have been conducted recently, there is still a lack of information about potential vectors of Plasmodium parasites, especially in Neotropical regions. Former studies with free-living and captive animals in São Paulo Zoo showed the presence of several Plasmodium and Haemoproteus species. In 2015, a pilot study was conducted at the zoo to collect mosquitoes in order to find out (i) which species of Culicidae are present in the study area, (ii) what are their blood meal sources, and (iii) to which Plasmodium species might they be potential vectors. At the same time, considering that Culex is the largest subgenus within the genus Culex with important vectors of diseases and that the correct identification of mosquitoes is critical for effective control strategies, an alternative identification method was tested. Thus, mosquitoes were identified morphologically, molecularly and by wing geometric morphometrics (WGM). Blood meal source and haemosporidian DNA were identified using molecular protocols. A total of 25 Culicidae species were identified, and six of them were positive for Plasmodium/Haemoproteus DNA. Ten mosquito species had their source of blood meal identified, which were mainly birds, including some species that were positive for haemosporidian parasites in the former study mentioned. WGM was used for eleven Culex species from São Paulo, Brazil, and one from Esquel, Argentina. The canonical variate analysis (CVA) was performed and a Neighbor-joining (NJ) tree was constructed to illustrate the patterns of species segregation. A cross-validated reclassification test was also carried out. From 110 comparisons in the cross-validated reclassification test, 87 yielded values higher than 70%, with 13 comparisons yielding 100% reclassification scores. Culex quinquefasciatus yielded the highest reclassification scores among the analyzed species, corroborating with the results obtained by the CVA, in which Cx. quinquefasciatus was the most distinct species. The high values obtained at the cross-validated reclassification test and in the NJ analysis as well as the segregation observed at the CVA made it possible to distinguish among Culex species with high degrees of confidence, suggesting that WGM is a reliable tool to identify Culex species of the subgenus Culex. Moreover, this study allowed us to expand the list of potential vectors of avian malaria parasites and to improve our knowledge of the evolutionary and ecological relationships between the highly diverse communities of birds, parasites, and vectors present at São Paulo Zoo (AU)

• FAPESP's process: 17/23407-0 - Mosquitoes (Culicidae, Diptera) in avian malaria transmission area: identification of potential vector species
• Grantee: Roseli França Simões
• Support Opportunities: Scholarships in Brazil - Master