Wolbachia Screening in Aedes aegypti and Culex pipiens Mosquitoes from Madeira Island, Portugal

Mosquito-borne diseases such as dengue and West Nile virus pose serious public health risks. On Madeira Island, the presence of the mosquito species <i>Aedes aegypti</i> (Linnaeus, 1762) and <i>Culex pipiens</i> (Linnaeus, 1758) raises concerns about local transmission. In this study, we tested 100 <i>Ae. aegypti</i> and 40 <i>Cx. pipiens</i> mosquitoes collected exclusively in the municipality of Funchal, Madeira Island, to assess the presence and diversity of <i>Wolbachia</i>, a naturally occurring bacterium known to reduce mosquitos' ability to transmit viruses. Molecular identification confirmed that all <i>Cx. pipiens</i> specimens belonged to the <i>molestus</i> biotype, with three individuals identified as hybrids between <i>molestus</i> and <i>pipiens</i> biotypes. This is the first evidence of such hybrids in Madeira. <i>Wolbachia</i> was not detected in any of the <i>Ae. aegypti</i> samples. In contrast, all <i>Cx. pipiens</i> mosquitoes were positive, showing a 100% prevalence. Genetic characterization placed these infections within the <i>w</i>Pip clade, supergroup B, sequence type 9. These findings provide key baseline data to inform future mosquito control strategies on the island. As <i>Ae. aegypti</i> showed no natural <i>Wolbachia</i> infection, introducing <i>Wolbachia</i>-infected mosquitoes may be necessary to implement such biocontrol approaches in Madeira.