Mosquitoes Know No Borders: Surveillance of Potential Introduction of Aedes Species in Southern Québec, Canada

Current climatic conditions limit the distribution of Aedes (Stegomyia) albopictus (Skuse, Diptera: Culicidae) in the north, but predictive climate models suggest this species could establish itself in southern Canada by 2040. A vector of chikungunya, dengue, yellow fever, Zika and West Nile viruses, the Ae. Albopictus has been detected in Windsor, Ontario since 2016. Given the potential public health implications, and knowing that Aedes spp. can easily be introduced by ground transportation, this study aimed to determine if specimens could be detected, using an adequate methodology, in southern Québec. Mosquitoes were sampled in 2016 and 2017 along the main roads connecting Canada and the U.S., using Biogent traps (Sentinel-2, Gravide Aedes traps) and ovitraps. Overall, 24 mosquito spp. were captured, excluding Ae. Albopictus, but detecting one Aedes (Stegomyia) aegypti (Skuse) specimen (laid eggs). The most frequent species among captured adults were Ochlerotatus triseriatus, Culex pipiens complex, and Ochlerotatus japonicus (31.0%, 26.0%, and 17.3%, respectively). The present study adds to the increasing number of studies reporting on the range expansions of these mosquito species, and suggests that ongoing monitoring, using multiple capture techniques targeting a wide range of species, may provide useful information to public health with respect to the growing risk of emerging mosquito-borne diseases in southern Canada.

A Multiplex PCR Assay for Six Aedini Species, Including Aedes albopictus

BackgroundMosquitoes, as vectors of various human pathogens, are significant drivers of serious human illness. In particular, those species in the Aedini tribe, which typically transmit dengue virus, Chikungunya fever virus, and Zika virus, are increasing their range because of climate change and international commerce. In order to prevent mosquito-borne disease, accurate mosquito species identification and monitoring are needed. The goal of this work was to develop a rapid and simple molecular diagnostic method for six morphologically similar Aedini species (Aedes flavopictus, Aedes albopictus, Ochlerotatus koreicus, Ochlerotatus japonicus, Ochlerotatus togoi, and Ochlerotatus hatorii) in Korea.MethodsIn total, 109 samples were used in this study. The internal transcribed spacer 2 (ITS2) regions from all six species were amplified, sequenced and analyzed using Mega 6. Once regions that were consistently different in sequence between all six species were identified, multiplex primers were designed to amplify them to generate species-specific fragments distinguishable by their size. ResultsUniquely sized fragments were generated in Aedes flavopictus (495bp), Aedes albopictus (438bp), Ochlerotatus koreicus (361bp), Ochlerotatus togoi (283bp), Ochlerotatus hatorii (220bp), and Ochlerotatus japonicus (160bp). Pairwise distance analysis showed that the difference was 35.0±1.5% between Aedes spp. and Ochlerotatus spp., 17.4±0.2% between Aedes albopictus and Aedes flavopictus, and 11.1±0.3% between Ochlerotatus koreicus and Ochlerotatus japonicus.ConclusionsIn this study, a multiplex PCR assay for six species of the Aedini tribe was developed. This assay is more accurate than morphological identification and will be useful for monitoring and controlling these vector mosquitoes.