Wolbachia in Aedes koreicus: Rare Detections and Possible Implications

SIMPLE SUMMARY: In Europe, the threat of emerging epidemic diseases also includes vector borne diseases. Several aedine mosquito species, showing vectorial capacity for pathogenic viruses, are invading, and expanding their ecological habitats. Aedes albopictus, a vector of Chikungunya, dengue, and Zika viruses, is well established in several European countries. In Italy, this species has been associated with public health issues, such as the Chikungunya outbreaks in 2007 and 2017, and by a dengue outbreak in 2020. Since 2011 a new invasive species, Aedes koreicus, has been recorded in Italy. The spreading of Ae. koreicus is presumably associated with passively spreading through the trading activity of specific goods among European countries, but multiple and independent introduction from native areas could be also possible. Given the risks associated with the presence of this vector, innovative and effective control measures are necessary. Recently, novel tools based on the use of symbiotic bacteria for the control of mosquito vectors have been proposed, focusing on Asaia and Wolbachia bacteria. Here, we report the first evidence of the presence of Wolbachia in a population of Ae. koreicus, cohabited by Asaia bacteria. These results open interesting prospects for the control of these invasive species. ABSTRACT: The emerging distribution of new alien mosquito species was recently described in Europe. In addition to the invasion of Aedes albopictus, several studies have focused on monitoring and controlling other invasive Aedes species, as Aedes koreicus and Aedes japonicus. Considering the increasing development of insecticide resistance in Aedes mosquitoes, new control strategies, including the use of bacterial host symbionts, are proposed. However, little is known about the bacterial communities associated with these species, thus the identification of possible candidates for Symbiotic Control is currently limited. The characterization of the natural microbiota of field-collected Ae. koreicus mosquitoes from North-East Italy through PCR screening, identified native infections of Wolbachia in this species that is also largely colonized by Asaia bacteria. Since Asaia and Wolbachia are proposed as novel tools for Symbiotic Control, our study supports their use for innovative control strategies against new invasive species. Although the presence of Asaia was previously characterized in Ae. koreicus, our study characterized this Wolbachia strain, also inferring its phylogenetic position. The co-presence of Wolbachia and Asaia may provide additional information about microbial competition in mosquito, and to select suitable phenotypes for the suppression of pathogen transmission and for the manipulation of host reproduction in Ae. koreicus.