Vector control: Discovery of Wolbachia in malaria vectors •

P. A. Ross and A. A. Hoffmann, Current Biology, 31:R738-R740. 2021.

Wolbachia bacteria are being widely released for suppression of dengue transmitted by Aedes mosquitoes. In the new study, Walker, Quek, Jeffries and colleagues present the best evidence yet for natural Wolbachia infections in Anopheles. Wolbachia were found in two species, An. demeilloni and An. moucheti, one of which is an important malaria vector. In contrast to many previous studies, the evidence for Wolbachia being present in these strains is convincing because the Wolbachia strains occurred at high frequencies in natural populations and at a high density within the mosquito. These strains had a high abundance in the microbiome, consistent with a previous study on the same species he authors provide additional lines of evidence for the Wolbachia being present in An. demeilloni and An. moucheti. Firstly, Wolbachia were visualized in the ovaries, a tissue critical for vertical maternal transmission of the infection. Secondly, Wolbachia persisted across laboratory generations, suggesting consistent maternal transmission. Whole genome sequencing of the Wolbachia strains showed that they were closely related to other Wolbachia strains found in mosquitoes, increasing the likelihood that these Wolbachia were not contaminants from other insect material.