Aedes species (Diptera: Culicidae) ecological and host feeding patterns in the north-eastern parts of South Africa, 2014-2018

Abstract

Background: There is a paucity of recent data and knowledge on mosquito diversity and potential vectors of arboviruses in South Africa, with most of the available data dating back to the 1950s-1970s. Aedes and Culex species are the major vectors of some of the principal arboviruses which have emerged and re-emerged in the past few decades.

Methods: In this study we used entomological surveillance in selected areas in the north-eastern parts of South Africa from 2014 to 2018 to assess mosquito diversity, with special emphasis on the Aedes species. The impact of trap types and environmental conditions was also investigated. Identification of the blood meal sources of engorged females collected during the study period was carried out, and DNA barcodes were generated for selected species.

Results: Overall, 18.5% of the total Culicidae mosquitoes collected belonged to the genus Aedes, with 14 species recognised or suspected vectors of arboviruses. Species belonging to the Neomelaniconion subgenus were commonly collected in the Bushveld savanna at conservation areas, especially Aedes mcintoshi and Aedes circumluteolus. Aedes aegypti was present in all sites, albeit in low numbers. Temperature was a limiting factor for the Aedes population, and they were almost exclusively collected at temperatures between 18 °C and 27 °C. The cytochrome oxidase subunit I (COI) barcode fragment was amplified for 21 Aedes species, and for nine of these species it was the first sequence information uploaded on GenBank.

Conclusion: This study provides a better understanding of the diversity and relative abundance of Aedes species in the north-east of South Africa. The information provided here will contribute to future arboviral research and implementation of efficient vector control and prevention strategies.

Keywords: Aedes; Africa; Disease vectors; Mosquitoes; South Africa.

Fig. 1

Mosquito collection sites and SAWS stations, South Africa, surveyed from January 2014 to May 2018. Squares indicate sentinel sites, triangles indicate ad hoc sites, and stars indicate SAWS stations

Fig. 2

Aedes mosquito abundance per trap-night from January 2014 to June 2018 at the sentinel sites

Fig. 3

Phylogenetic tree of sequences from Aedes mosquitoes based on 111 sequences and 507 base pairs of COI gene. The tree was constructed with MEGA 7, using the maximum likelihood method and the Tamura-Nei model with 1000 bootstrap replicates. The tree with the highest log likelihood (−6035.72) is shown. GenBank accession numbers are indicated. Numbers on internal branches indicate bootstrap values. Samples which are part of this study are marked with a black triangle