Temporal patterns of abundance of Aedes aegypti and Aedes albopictus (Diptera: Culicidae) and mitochondrial DNA analysis of Ae. albopictus in the Central African Republic

Abstract

The invasive Asian tiger mosquito Aedes albopictus (Diptera: Culicidae) was first reported in central Africa in 2000, in Cameroon, with the indigenous mosquito species Ae. aegypti (Diptera: Culicidae). Today, this invasive species is present in almost all countries of the region, including the Central African Republic (CAR), where it was first recorded in 2009. As invasive species of mosquitoes can affect the distribution of native species, resulting in new patterns of vectors and concomitant risk for disease, we undertook a comparative study early and late in the wet season in the capital and the main cities of CAR to document infestation and the ecological preferences of the two species. In addition, we determined the probable geographical origin of invasive populations of Ae. albopictus with two mitochondrial DNA genes, COI and ND5. Analysis revealed that Ae. aegypti was more abundant earlier in the wet season and Ae. albopictus in the late wet season. Used tyres were the most heavily colonized productive larval habitats for both species in both seasons. The invasive species Ae. albopictus predominated over the resident species at all sites in which the two species were sympatric. Mitochondrial DNA analysis revealed broad low genetic diversity, confirming recent introduction of Ae. albopictus in CAR. Phylogeographical analysis based on COI polymorphism indicated that the Ae. albopictus haplotype in the CAR population segregated into two lineages, suggesting multiple sources of Ae. albopictus. These data may have important implications for vector control strategies in central Africa.

Figure 1. Location of mosquito sampling sites in the Central African Republic.

Figure 2. Total abundance of immature stages of Aedes aegypti and Ae. albopictus per container.

Each two-letter abbreviation on the x-axis corresponds to a type of container as follows: WS, water storage; FP, flower pot; WP, watering place; UT, used tyres; DT, discarded tanks; MI, miscellaneous; NA, natural.

Figure 3. Spatial distribution of surveyed houses and positive larval habitats of Aedes spp. in Bangui.

The surveys were conducted during the early wet season (A) and the late wet season (B).

Figure 4. Bayesian inference hypothesis of Ae. albopictus phylogeny based on COI (A) and ND5 (B) sequence data.

The phylogeny was constructed with MrBayes 3.1.2, ngen = 2 000 000. Best-fitting models selected with the MR model test (under AIC) were HKY for COI and HKY+I+G for the ND5 nucleotide datasets. Branch support is indicated by the posterior probability values. Accession numbers of COI and ND5 out-group sequences are given in supporting information file Table S1.