Arthropod-borne viruses are transmitted by blood-sucking insects to animals and humans. Most of them, are transmitted by mosquitoes [1, 2]. There are 43 genera and 3,530 species of mosquitoes in the world, however, species belonging to the genera Aedes, Anopheles, and Culex, are the main vectors of mosquito borne diseases [3, 4]. In particular, mosquitoes belonging to the genus Aedes are becoming the main vectors for spreading fatal diseases such as chikungunya, dengue fever, yellow fever, and Zika virus, that often occur in Asian countries [4, 5, 6]. As mosquito borne diseases may grow in the future due to fast globalization and climate change, more information is needed [2, 7].
Mitochondrial genes are widely used in research on molecular evolution and population genetics of vector insects. Because they have a relatively high mutation rate, and high levels of polymorphism and divergence due to their inherent sensitivity, they are highly useful as molecular markers [8, 9, 10, 11]. Many vector studies have investigated where the population was introduced using mitochondrial genes [12, 13]. Population structure and genetic diversity between populations can affect vector capacity [14]. The understanding of these factors is necessary for vector control [15].
Aedes albopictus, originally from Southeast Asia, has recently spread all over the world except for Antarctica, and is considered one of the most dangerous alien species [16, 17, 18]. The first record of Ae. albopictus in South Korea was in 1940, and its distribution has recently expanded throughout the Korean peninsula [19, 20]. Together with Aedes aegypti, substantial research attention has been paid to Ae. albopictus as major players in the transmission of vector-borne diseases [21, 22, 23]. The main reason for the global expansion is that larvae are introduced through used tires, bamboo, etc., due to human activities [24, 25]. Additionally, the range of habitats they can live in has widened as a result of the temperature rise due to global warming [26, 27]. Ae. Albopictus’ eggs have been shown to tolerate cold weather, and have the potential to expand its distribution in colder regions [28, 29].
Aedes flavopictus is original from East Asia, including Japan and South Korea, and is widely distributed in that region, but there are morphological and genetic differences depending on the geographical range [30, 31]. It has been found that Ae. flavopictus' eggs can survive in colder environments than Ae. albopictus [32] and recently expanded its distribution from East Asia to European countries [33, 34, 35]. According to the results of continuous monitoring on the Korean Peninsula, the frequency of appearance of Ae. flavopictus is not high [20, 36, 37, 38]. Ae. flavopictus is not known to act as a vector like Ae. albopictus and other Aedes species, but it has previously been shown that it may propagate dengue fever [30, 39, 40].
Since the two species are distributed over a wide area in Korea and Japan and share a common habitat [31, 41, 42], attention over their overlapping distribution is gradually increasing, and it is said that there is a possibility of interspecific crossing [43, 44, 45]. Not only do the distributions overlap, but the two morphologies are similar [31, 35, 46], and Japanese studies have shown that the two are phylogenetically close to each other [47, 48]. As Ae. albopictus and Ae. flavopictus are closely related species and have similar ecological roles and habitats, they can be compared to each other.
The Korean Peninsula has various climates and geographical environments, and the diversity of arthropods that transmit arthropod-borne viruses is also high [49, 50]. There are 11 genera and 56 species of mosquitoes in Korea, including 19 species in the genus Aedes. The presence of Ae. albopictus and Ae. flavopictus was recorded in Korea in the past [19, 51, 52]. Since malaria and Japanese encephalitis occur frequently in Korea, only studies have focused on the vectors of these conditions, and the genus Aedes has not been investigated [53, 54, 55]. There are cases in which foreign mosquitoes have become indigenous bringing infections from abroad. Additionally, but Korea also has steadily imported patients, so it is not possible to say that it is a clean country for viruses mediated by Aedes, so it is necessary to establish a preemptive control strategy [56, 57].
This study compared the genetic diversity and structure of two species of Aedes mosquitoes living in Korea through two mitochondrial genes with the aim of monitoring mosquito populations. With this work, we intend to create basic data to establish vector control strategies.