DNA barcoding reveals an increased diversity within the genus Culex (Diptera: Culicidae) in Ireland

Arthropod populations are changing globally due to the combined impacts of climate change, land-use transformation, globalisation and trade. Changes in arthropod populations can potentially result in the decline and extinction of some native and/or endemic species, while other species that potentially pose threats may increase. Such dynamics lead to weakened ecosystem resilience, which can facilitate the establishment and spread of species with vector capabilities, such as mosquitoes. While many of the mosquito species present in Ireland possess vector capabilities, populations have not been nationally surveyed since 1991. At that time, species identification relied on morphological examination, a method that was even then recognised as inadequate for differentiating certain species within complexes. In this study, we present the first DNA barcoding investigation of Irish mosquito populations and reveal species and hidden diversity not previously recognised in Ireland. These include two potential new species/ecotypes, Culex torrentium and Culex pipiens form pipiens, which were recorded for the first time in Ireland. We demonstrate that barcoding with Cytochrome C Oxidase Subunit 1 (COI) based primers is suitable for the majority of species-level identifications. However, additional primer sets targeting the Internal Transcribed Spacer regions 1 and 2 (ITS1 and ITS2) were necessary to differentiate species within the Culex pipiens complex. The multi-locus approach employed in this study can enhance national surveillance efforts, especially in monitoring mosquitoes that may transmit vector-borne diseases, and in recognising increased species diversity from a biodiversity perspective.