The spread of the invasive mosquito Aedes albopictus (Diptera: Culicidae) in Portugal: a first genetic analysis

Background Aedes albopictus , commonly known as the Asian tiger mosquito, has become one of the most invasive mosquito species, introduced and established in various tropical and temperate regions worldwide over the last five decades. First reported in Europe in 1979 in Albania and later in Italy in 1990, the species is now established in 13 EU/EEA countries and 337 regions (2023). In Portugal, Ae. albopictus was first detected in the Algarve and Penafiel regions in 2017, followed by Alentejo in 2022 and Lisbon in 2023. This mosquito species poses a significant public health risk as a vector for numerous pathogenic viruses, including dengue, Zika and chikungunya. Methods Aedes albopictus collected in Lisbon in 2023, were analyzed using COX gene sequencing to understand their genetic relationships. Results Our data indicate that the Ae. albopictus mosquito populations detected in three different locations in Lisbon in 2023 correspond to recent, but distinct introduction events. Conclusions Although there has been no local transmission of Aedes -transmitted viruses in mainland Portugal to date, the spread of the mosquito and increased international travel increase the risk of Aedes -borne disease outbreaks. The ongoing spread of Ae. albopictus in the country and the confirmed multiple introductions in new locations raise awareness of the need to monitor mosquito vectors in order to control and prevent autochthonous Aedes -borne disease outbreaks.