A new scientific study has revealed that a single mosquito species now dominates much of central Gabon, which raises concerns about the potential spread of dengue, chikungunya, Zika and other mosquito-borne diseases.
Researchers who conducted a two-year survey across urban, peri-urban and rural areas of Moyen-Ogooué Province found that Aedes albopictus, commonly known as the Asian tiger mosquito, accounted for more than half of all mosquitoes collected during the study period.
The research, published in Scientific Reports, involved mosquito sampling between March 2023 and January 2025. Scientists collected 22,216 mosquitoes representing 21 species from eight genera, making it one of the most comprehensive mosquito surveys ever conducted in the region.
According to the study, “Aedes albopictus was the most prevalent mosquito species, making up 52.5% of all specimens collected.”
The species is a known carrier of several viral diseases, including dengue, chikungunya, yellow fever and Zika, all of which have previously been reported in Gabon and other parts of Central Africa.
Researchers found significant differences in mosquito populations across different environments. Rural areas recorded the highest number of mosquito species, while urban communities were dominated by only a few mosquito types.
“Urban communities were species-poor and strongly dominated by Aedes albopictus and Culex quinquefasciatus,” authors wrote.
Scientists also observed major seasonal changes in mosquito abundance. Mosquito numbers increased sharply during the rainy season when standing water created ideal breeding conditions. During this period, Aedes albopictus became overwhelmingly dominant, accounting for more than 60 percent of all mosquitoes collected.
The findings suggest that disease transmission risks may vary throughout the year, with wetter months creating favourable conditions for mosquito population growth.
One of the most striking discoveries was the expansion of Aedes albopictus into rural environments, where it was found in exceptionally high numbers. Researchers say this shift points to significant ecological changes in mosquito populations across the province.
“The unexpected rural dominance of Aedes albopictus creates shifting windows of vulnerability for human populations,” authors wrote.
In addition to documenting widespread dominance of the species, researchers identified six mosquito species that had never before been reported in Gabon, highlighting the country’s diverse and previously underestimated mosquito diversity.
The authors argue that disease surveillance programmes should not focus solely on major urban centres, as rural and peri-urban areas also host mosquito populations capable of transmitting viruses.
“Biodiversity-wide surveillance, not only of major vectors, is therefore essential for understanding and anticipating arbovirus circulation in this ecologically complex region,” they wrote.