Population Genetics of Culex tritaeniorhynchus (Diptera: Culicidae) in Türkiye

Acta Parasitologica (2024) 69:1157–1171 https://doi.org/10.1007/s11686-024-00844-9 ORIGINAL PAPER Population Genetics of Culex tritaeniorhynchus (Diptera: Culicidae) in Türkiye Fatma Bursali1 · Fatih Mehmet Simsek1 Received: 14 November 2023 / Accepted: 26 March 2024 / Published online: 9 April 2024 © The Author(s) 2024 Abstract Purpose Mosquitoes are important vectors of pathogens that can affect humans and animals. Culex tritaeniorhynchus is an important vector of arboviruses such as Japanese encephalitis virus, West Nile virus among various human and animal communities. These diseases are of major public health concern and can have huge economic and health burdens in prevalent countries. Although populations of this important mosquito species have been detected in the Mediterranean and Aegean regions of Türkiye; little is known about its population structure. Our study is to examine the population genetics and genetic composition of Cx. tritaeniorhynchus mosquitoes collected from several localities using cytochrome oxidase subunit I (COI) and the NADH dehydrogenase subunit 5 genes (ND5). This is the first extensive study of Cx. tritaeniorhynchus in the mainland Türkiye with sampling spanning many of provinces. Methods In this study, DNA extraction, amplification of mitochondrial COI and ND5 genes and population genetic analyses were performed on ten geographic populations of Culex tritaeniorhynchus in the Aegean and Mediterranean region of Türkiye. Results Between 2019 and 2020, 96 samples were collected from 10 geographic populations in the Aegean and Mediterranean regions; they were molecularly analyzed and 139 sequences (50 sequence for COI and 89 sequence for ND5) were used to determine the population structure and genetic diversity. For ND5 gene region, the samples produced 24 haplotypes derived from 15 variable sites and for COI gene region, 43 haplotypes were derived from 17 variable sites. The haplotype for both gene regions was higher than nucleotide diversity. Haplotype phylogeny revealed two groups present in all populations. AMOVA test results show that the geographical populations were the same for all gene regions. Results suggest that Cx. tritaeniorhynchus is a native population in Türkiye, the species is progressing towards speciation and there is no genetic differentiation between provinces and regions. Conclusion This study provides useful information on the molecular identifcation and genetic diversity of Cx. tritaeniorhynchus; these results are important to improve mosquito control programs. Keywords Culex tritaeniorhynchus · Population genetics · mtND5 · mtCOI · Distribution · Türkiye Introduction Culex is an important and diverse genus that encompasses more than 770 species grouped into twenty-six subgenera, several of which are of major public health concern [1]. Culex tritaeniorhynchus Giles is a cosmopolitan species widely distributed in Africa, Southeast Asia, Middle East Fatma Bursali 1 Faculty of Science, Department of Biology, Aydın Adnan Menderes University, Aydın 09100, Türkiye and Europe. It primarily breeds in marshes, paddy fields. Taxonomically, this species is a member of the Vishnui subgroup along with Cx. pseudovishnui, Cx. vishnui, Cx. perplexus and Cx. incognitus [2, 3]. Its distribution around the world seems to be dependent on both climate and altitude [4]. It has a patchy distribution, restricted in some provinces in the Aegean, Mediterranean, and Thrace regions in Türkiye [5–8]. It is a zoophilic and exophilic species that can acquire zoonotic pathogens from natural and/or amplifying reservoir hosts including cows, birds, pigs, horses etc [9–11]. Culex tritaeniorhynchus is an important vector of arboviruses such as Japanese encephalitis virus (JEV), Rift valley 13 1158 fever, West Nile virus (WNV) and Tembusu virus among various human and animal communities [12]. These Culextransmitted disease can leave huge economic and health burdens in prevalent countries. WNV and Japanese encephalitis (JE) are one of the serious transmitted infections. They are caused by RNA viruses in the Flaviviridae family and similarly affect the central nervous system of host. WNV is prevalent in Africa, Europe, the Middle East, North America and West Asia [13, 14]. There have been reports of WNV cases and outbreaks in several European countries with the largest occurring in Israel, Greece, Romania, and Russia; between 2010 and 2022. There has been over 5,800 reported human cases and 378 deaths reported [15, 16]. JE, in contrast, is endemic in rural agricultural areas in the East Asia, with an estimated 70,000 cases and a mortality rate of 25–30% reported annually. Children aged ≤ 12 years are the most affected group [17, 18]. Although no JEV has been reported in Türkiye, there have been outbreaks of WNV; 47 WNV cases with 10 fatalities in 2010 [19]. In the following period, 7, 23 and 10 WNV cases were reported in Türkiye in 2017, 2018 and 2019, respectively [20]. Therefore, effective vector control, early detection of new vector species and ongoing vector surveillance are very important in combating these arboviral diseases. The success of vector control efforts to accurately identify the targeted mosquito species, depends on a correct understanding of their biology and ecology. Additionally, many taxonomists evaluate behavioral and population biology data together in identifying and classifying a species [21]. In recent years, numerous molecular phylogeny and population genetics studies have estimated the patterns of relatedness among and between important mosquito species [22–26]. Molecular markers have been developed to distinguish and identify mosquito species, replacing the limitations of morphological identification, which can be challenging for closely related species and requires welltrained technicians [27]. DNA barcoding markers are frequently used for mosquito species differentiation. These studies are important as they provide valuable information on past biogeographic events and potential associations with life history traits of insect vectors. In Türkiye several studies have looked at the population structure of mosquito species such as Aedes zammitii [28], Ae. phoeniciae [29], Ae. albopictus [30], Ae. aegypti [31], Cx. pipiens [32]. Most recently, Gunay et al. [7] investigated the taxonomic status of the Culex fauna in Türkiye using both morphological and DNA barcoding techniques. This work successfully determined or confirmed the presence of Cx. tritaeniorhynchus and 15 other Culex species, including four newly discovered species; however, no reports exist on the genetic structure of Cx. tritaeniorhynchus. Population genetic studies are important for the development of vector control measures, 13 Acta Parasitologica (2024) 69:1157–1171 especially genetic control, to prevent or reduce the effects of epidemic diseases. mtCOI DNA barcode regions are commonly used to distinguish mosquito species [33, 34]. Ergunay et (...truncated)