Mosquitoes (Diptera: Culicidae) are widespread over the whole Northwestern Region of RussiaFootnote 1 (NWR, Fig. 1). Females of some mosquito species bite humans and are responsible for the transmission of medically important pathogens and parasites such as viruses, bacteria, protozoans, and nematodes. For example, Sindbis, Batai, and California encephalitis viruses are known to be transmitted in NWR by mosquitoes of the genera AedesFootnote 2 Meigen, 1818, Anopheles Meigen, 1818, and Culex Linnaeus, 1758 (Lvov et al., 1989; Alkhovsky, 2016). A study of the associations between mosquitoes and specific pathogens requires both correct identification of the vector species and reliable data on the mosquito fauna in the study region.

Fig. 1.
figure 1

The Northwestern Region of Russia.

In this article we continue the study of bloodsucking insects in NWR, which has been carried out at the Zoological Institute of the Russian Academy of Sciences (ZIN) since 2005. First, we made a general outline of the regional faunas of mosquitoes, blackflies (Simuliidae), horseflies (Tabanidae), and biting midges (Ceratopogonidae) (Medvedev et al., 2007); then mosquito distribution was considered in greater detail (Aibulatov and Khalin, 2019; Aibulatov et al., 2020; Khalin and Aibulatov, 2020, 2021).

During further analysis of the northern range boundaries we have mapped the records of 16 mosquito species of the genera Anopheles, Coquillettidia Dyar, 1905, Culex, and Culiseta Felt, 1904 in the whole territory of NWR. In this article we examine all the species of Culicidae present in the NWR fauna, with the exception of Aedes species. We use our earlier data (Khalin and Aibulatov, 2020), e.g., the results of identification of the material collected by S.V. Aibulatov and A.V. Khalin and revision of the ZIN collection. In addition, it includes analysis of additional literature for some regions of NWR.

The distribution within NWR has been described for the following species: Anopheles atroparvus van Thiel, 1927, A. beklemishevi Stegnii et Kabanova, 1976, A. claviger (Meigen, 1804), A. maculipennis Meigen, 1818, A. messeae Falleroni, 1926, Culex modestus Ficalbi, 1890, C. pipiens Linnaeus, 1758, C. torrentium Martini, 1925, C. territans Walker, 1856, Culiseta fumipennis (Stephens, 1825), C. morsitans (Theobald, 1901), C. ochroptera (Peus, 1935), C. alaskaensis (Ludlow, 1906), C. annulata (Schrank, 1776), C. bergrothi (Edwards, 1921), and Coquillettidia richiardii (Ficalbi, 1889).

The coordinates of the collection localities of each species were entered in a *.shp file and analyzed using an ArcGIS 10 software. In addition, the file included data on the source of information: our collections, ZIN collection, and literature data. The geographic information system (GIS) is useful for analysis of the records of bloodsucking insect species and description of their geographic distribution. For instance, the mapped species records can be combined with various thematic maps (e.g., climatic ones), containing the original parameters in the given points of the territory or interpolated results based on analysis of the distribution of factors. In this way, the known collection localities of a given species can be used to extrapolate its range boundaries in the region.

Mosquitoes are poikilothermic animals whose metabolism and phenology directly depend on the environmental conditions; therefore, they can exist only within a certain range of environmental factors. In the article, the records of mosquito species were related to a climatic parameter, the sum of active temperatures above 0°C (SAT)Footnote 3. The benefis of using SAT in the study of mosquito distribution had been noted earlier (e.g., Yasyukevich et al., 2017, 2019). Various climatic parameters are considered when predicting the changes in the distribution of agents of transmissible diseases and of their vectors (Pavlovsky, 1964; Korenberg, 1975). In medical entomology and practical epidemiology, thermal parameters are used to control malaria and other diseases in a given territory (Beklemishev et al., 1949; Moshkovsky and Rashina, 1951). The pest control measures in agriculture is determined by the thermal parameters of insect pest development (Popova and Popov, 2013).

In this research we used the free data on the main climatic factors available at the AgroAtlas web site (Afonin et al., 2008) in order to characterize the mosquito distribution in NWR in relation to the environmental parameters. The records of mosquito species close to the northern boundaries of their ranges were compared with the SAT values of the corresponding territories, and the results were used to extrapolate the northern distribution boundaries of 16 species of Culicidae within NWR. We used the SAT values for areas of 100 km2, obtained from the AgroAtlas web site (Afonin et al., 2008). The SAT values were color coded from green to red (see map legend in Fig. 2).

Fig. 2.
figure 2

Collection localities of Anopheles atroparvus van Thiel (black triangles) and A. beklemishevi Stegnii et Kabanova (white triangles) in Northwestern Russia, according to the literature data. The territories with different values of the sum of active temperatures above 0°C are color coded (see legend).

Below, the records of 16 mosquito species are plotted on the map of NWR with SAT values. The source of information is indicated for each species: our collections, the ZIN material or literature data.

The northernmost records of mosquito species within NWR, including the exact collection localities and their coordinates, were considered in our earlier paper (Khalin and Aibulatov, 2021). The records of mosquitoes from the territories with the minimal SAT values are listed in Table 1. The number of such records given for each species reflects the current level of knowledge of its distribution. A single locality corresponding to the territory with the lowest SAT value is given in some cases: Anopheles atroparvus, Culiseta fumipennis, and C. annulata. For most species, two localities are given, in the western and the eastern parts of NWR. For example, such localities for Anopheles beklemishevi are RK in the west and Komi in the east of NWR. For the species whose distribution is somewhat better known, three localities are listed in order to describe the northern range boundary more correctly; for example, the localities of Anopheles claviger are SPb (western part), VP (central part), and Komi (eastern part). Some records of species are considered by us to be doubtful; they are marked with asterisks (*) and discussed in the corresponding Note sections.

Table 1. Records of mosquitoes in Northwestern Russia corresponding to the territories with the lowest values of the sums of active temperatures (SAT) above 0°C

Maps of NWR showing the collection localities of the 16 mosquito species are given below. For each species, the examined material (our collections and the ZIN collection) is listed when present, its distribution in NWR and adjacent territories is characterized, and references to the sources of data are provided. In addition, the distribution of each species outside NWR is briefly described based on the literature data (Gutsevich et al., 1970; Khalin and Gornostaeva, 2008; Becker et al., 2010). The records for Belarus are based on the data of Suslo (2019); those in EuropeFootnote 4 are based on the data of Robert and co-authors (Robert et al., 2019). The distribution of Culiseta species in Russia outside NWR is based on the data of Maslov (1967).

RECORDS OF MOSQUITO SPECIES IN NORTHWESTERN RUSSIA

Anopheles (Anopheles) atroparvus van Thiel, 1927

Distribution. KP (Levenson et al., 1959) (Fig. 2).

Sweden (Dahl, 1977; Lundström et al., 2013). Latvia (Spungis, 2000). Lithuania (Pakalniskis et al., 2006).

South of European Russia. Europe (ranging northward to the UK, Belgium, and Denmark); Belarus, Ukraine, Moldova.

Anopheles (Anopheles) beklemishevi Stegnii et Kabanova, 1976

Distribution (Fig. 2). RK (Stegnii et al., 1978; Perevozkin et al., 2012). LP (Stegnii et al., 1978; Moskaev et al., 2016). VP (Belova et al., 2008). Komi (Panyukova and Ostroushko, 2017). NP (Moskaev et al., 2015).

Sweden (Lundström et al., 2013). Finland (Culverwell et al., 2021).

European Russia, Siberia. Sweden, Finland.

Anopheles (Anopheles) claviger (Meigen, 1804)

Material. SPb, LP, VP (Fig. 3).

Distribution. SPb (Fedorov, 1969). Komi (Panyukova and Ostroushko, 2017). KP (Levenson et al., 1959). PP (Pavlovsky, 1935; Medvedev and Matov, 1999). NP (Medvedev and Panyukova, 2005).

Fig. 3.
figure 3

Collection localities of Anopheles claviger (Meigen) in Northwestern Russia, according to the collection material (circles) and the literature data (triangles).

Norway (Mehl, 1996). Sweden (Dahl, 1975; Schäfer and Lundström, 2001; Lundström et al., 2013; Möhlmann et al., 2017). Finland (Utrio, 1977; Culverwell, 2018; Culverwell et al., 2021). Estonia (Remm, 1957). Latvia (Spungis, 2000). Lithuania (Pakalniskis et al., 2006).

European Russia, West Siberia. Europe (ranging northward to the UK, Belgium, and Denmark); North Africa, Belarus, Ukraine, Moldova, Transcaucasia, West and Middle Asia.

Anopheles (Anopheles) maculipennis Meigen, 1818 sensu strictoFootnote 5

Distribution (Fig. 4). RK (Perevozkin et al., 2012; Jakovlev et al., 2014). LP (Stegnii et al., 1978; Moskaev et al., 2016). Komi (Gordeev and Moskaev, 2014; Panyukova and Ostroushko, 2017). NP (Moskaev et al., 2015). KP (Levenson et al., 1959; Bernotiene, 2012; Perevozkin et al., 2018).

Fig. 4.
figure 4

Collection localities of Anopheles maculipennis Meigen in Northwestern Russia. Designations as in Fig. 3.

Sweden (Dahl, 1977; Lundström et al., 2013; Möhlmann et al., 2017). Finland (Utrio, 1977; Culverwell, 2018; Culverwell et al., 2021). Latvia (Spungis, 2000). Lithuania (Pakalniskis et al., 2006).

European Russia, West Siberia. Europe (ranging northward to the UK, Belgium, and Denmark); North Africa, Belarus, Ukraine, Moldova, Transcaucasia, West and Middle Asia.

Anopheles (Anopheles) messeae Falleroni, 1926

Material. MP* (Fig. 5).

Distribution. AP (Sharkov, 1982). RK (Lobkova, 1956; Stegnii et al., 1978; Perevozkin et al., 2012). SPb (Fedorov, 1969; Stegnii et al., 1978). LP (Stegnii et al., 1978; Moskaev et al., 2016). VP (Sharkov, 1982; Belova et al., 2008). Komi (Ostroushko, 1986; Panyukova and Ostroushko, 2017). PP (Chetverikova, 2014). NP (Moskaev et al., 2015). KP (Levenson et al., 1959; Perevozkin et al., 2018).

Fig. 5.
figure 5

Collection localities of Anopheles messeae Falleroni in Northwestern Russia. Designations as in Fig. 3. The location with doubtful species identification is shown in purple.

Norway (Mehl, 1996). Sweden (Dahl, 1977; Lundström et al., 2013). Finland (Utrio, 1977; Culverwell, 2018; Culverwell et al., 2021). Latvia (Spungis, 2000). Lithuania (Pakalniskis et al., 2006).

European Russia, Siberia. Europe (ranging northward to the UK, Belgium, and Denmark); Belarus, Ukraine, Moldova, Middle Asia, Northeast China.

Note. The only specimen studied by us is a head preparation of a female mosquito identified earlier by A.V. Gutsevich. We cannot confirm this identification. It is possible that the female was reared from an egg identified as Anopheles messeae.

Culex (Barraudius) modestus Ficalbi, 1890

Material. SPb, LP (Fig. 6).

Fig. 6.
figure 6

Collection localities of Culex modestus Ficalbi in Northwestern Russia. Designations as in Fig. 3.

Distribution. VP (Belova et al., 2008). PP (Medvedev and Matov, 1999). NP (Panyukova and Medvedev, 2008).

Sweden (Möhlmann et al., 2017).

European Russia, Siberia, the Russian Far East. Europe (ranging northward to the UK, the Netherlands, and Denmark); North Africa, Belarus, Ukraine, Moldova, Transcaucasia, West, Middle, and South Asia.

Culex (Culex) pipiens Linnaeus, 1758

Material. MP, RK, SPb, LP, KP, PP, NP (Fig. 7).

Fig. 7.
figure 7

Collection localities of Culex pipiens Linnaeus in Northwestern Russia. Designations as in Figs. 3, 5.

Distribution. MP (Shub and Nikolaev, 1937; Lobkova, 1964; Tamarina and Aleksandrova, 1974; Sharkov, 1976). AP* (Sack, 1923). NAO* (de Meijere, 1910). RK (Shingareva, 1926; Shub and Nikolaev, 1937; Lobkova, 1956, 1980; Lobkova and Makarova, 1961; Sharkov et al., 1984; Polevoi, 2006). SPb (Osten-Sacken, 1858; Fedorov, 1946, 1969; Gutsevich, 1948). VP (Adrianov, 1953; Ozerov, 1957; Sharkov, 1982; Belova et al., 2008). Komi (Shub and Nikolaev, 1937; Ostroushko, 1986; Panyukova and Ostroushko, 2017). KP (Levenson et al., 1959; Bernotiene, 2012). PP (Medvedev and Matov, 1999; Chetverikova, 2014). NP (Fedorova, 1977; Kunkova, 2000; Panyukova and Medvedev, 2008).

Norway (Natvig, 1948; Mehl, 1996). Sweden (Natvig, 1948; Dahl, 1975; Schäfer and Lundström, 2001; Lundström et al., 2013; Hesson et al., 2015; Möhlmann et al., 2017). Finland (Natvig, 1948; Utrio, 1977; Culverwell, 2018; Culverwell et al., 2021). Estonia (Remm, 1957). Latvia (Spungis, 2000). Lithuania (Pakalniskis et al., 2006).

European Russia, Siberia, the Russian Far East. Europe (ranging northward to the UK, Belgium, and Denmark); North Africa, Belarus, Ukraine, Moldova, West and Middle Asia. Holarctic (excluding most transpolar regions), locally in the Ethiopian, Neotropical, and Australian regions.

Note. The records of Culex pipiens from AP [the Novaya Zemlya Archipelago, Belushya Bay (Sack, 1923)] and NAO [Zapolyarnyi District, Vaygach Island (de Meijere, 1910)] were probably based on misidentification. The other records are located far southward from the Novaya Zemlya and Vaygach Island (Table 1; Fig. 7), including those outside Russia, in Sweden: Norrbotten, 67°08ʹ09.0ʺN, 18°30ʹ03.5ʺE (Lundström et al., 2013) and Haparanda, 65°49ʹ60.0ʺN, 24°07ʹ60.0ʺE (Hesson et al., 2015); in Finland: Lahti, 60°58ʹ60.0ʺN, 25°39ʹ20.0ʺE (Hesson et al., 2015) and Larsmo, 63°45′N, 22°48′E (Natvig, 1948).

Culex (Culex) torrentium Martini, 1925

Material. SPb, LP, NP (Fig. 8).

Fig. 8.
figure 8

Collection localities of Culex torrentium Martini in Northwestern Russia. Designations as in Fig. 3.

Distribution. RK (Polevoi, 2006). SPb (Fedorov, 1969). VP (Belova et al., 2008). Komi (Panyukova, 2019). PP (Chetverikova, 2014). NP (Kunkova and Fedorova, 2003; Panyukova and Medvedev, 2008).

Norway (Mehl, 1996). Sweden (Schäfer and Lundström, 2001; Lundström et al., 2013; Hesson et al., 2015). Finland (Utrio, 1977; Culverwell, 2018; Culverwell et al., 2021). Estonia (Remm, 1957). Lithuania (Pakalniskis et al., 2006).

European Russia, West Siberia. Europe (ranging northward to the UK, Belgium, and Denmark); Belarus, Moldova, West Asia.

Culex (Neoculex) territans Walker, 1856

Material. RK, SPb, LP, NP (Fig. 9).

Fig. 9.
figure 9

Collection localities of Culex territans Walker in Northwestern Russia. Designations as in Fig. 3.

Distribution. RK (Lobkova, 1964; Jakovlev et al., 2014). SPb (Fedorov, 1969). VP (Belova et al., 2008). Komi (Panyukova and Ostroushko, 2017). PP (Medvedev and Matov, 1999). NP (Panyukova and Medvedev, 2008).

Norway (Natvig, 1948; Mehl, 1996). Sweden (Natvig, 1948; Schäfer and Lundström, 2001; Lundström et al., 2013). Finland (Natvig, 1948; Utrio, 1977; Culverwell, 2018; Culverwell et al., 2021). Estonia (Remm, 1957). Lithuania (Pakalniskis et al., 2006).

European Russia, Siberia, the Russian Far East. Europe (ranging northward to the UK, Belgium, and Denmark); North Africa, Belarus, Moldova, West and Middle Asia; North America.

Culiseta (Culisella) fumipennis (Stephens, 1825)

Material. RK, SPb, LP (Fig. 10).

Fig. 10.
figure 10

Collection localities of Culiseta fumipennis (Stephens) in Northwestern Russia. Designations as in Fig. 3.

Distribution. RK (Humala and Polevoi, 2009; Jakovlev et al., 2014). SPb (Gutsevich, 1948).

Norway (Natvig, 1948; Mehl, 1996). Sweden (Natvig, 1948; Schäfer and Lundström, 2001; Lundström et al., 2013). Estonia (Remm, 1957).

European Russia (north and west), south of West Siberia. Europe (ranging northward to the UK, Belgium, and Denmark); North Africa, Belarus, Ukraine, West Asia.

Culiseta (Culisella) morsitans (Theobald, 1901)

Material. MP, RK, SPb, LP, PP (Fig. 11).

Fig. 11.
figure 11

Collection localities of Culiseta morsitans (Theobald) in Northwestern Russia. Designations as in Fig. 3.

Distribution. RK (Lobkova, 1964, 1965). SPb (Gutsevich, 1948; Fedorov, 1969). Komi (Ostroushko, 1986; Panyukova and Ostroushko, 2017). KP (Bernotiene, 2012). PP (Medvedev and Matov, 1999). NP (Panyukova and Medvedev, 2008).

Norway (Natvig, 1948; Mehl, 1996). Sweden (Natvig, 1948; Schäfer and Lundström, 2001; Lundström et al., 2013; Hesson et al., 2015; Möhlmann et al., 2017). Finland (Natvig, 1948; Utrio, 1977; Culverwell, 2018; Culverwell et al., 2021). Estonia (Remm, 1957). Lithuania (Pakalniskis et al., 2006).

European Russia (northwest, west, center), south of West Siberia. Europe (ranging northward to the UK, Belgium, and Denmark); North Africa, Belarus, Ukraine, West Asia.

Culiseta (Culisella) ochroptera (Peus, 1935)

Material. RK, SPb, LP (Fig. 12).

Fig. 12.
figure 12

Collection localities of Culiseta ochroptera (Peus) in Northwestern Russia. Designations as in Fig. 3.

Distribution. AP (Shevkunova and Gracheva, 1961). RK (Polevoi, 2006; Jakovlev et al., 2014). SPb (Fedorov, 1946, 1969). Komi (Panyukova and Ostroushko, 2017). KP (Bernotiene, 2012). NP (Panyukova and Medvedev, 2008).

Norway (Mehl, 1996). Sweden (Schäfer and Lundström, 2001; Lundström et al., 2013; Möhlmann et al., 2017). Finland (Utrio, 1977; Culverwell et al., 2021). Estonia (Remm, 1957). Lithuania (Pakalniskis et al., 2006).

European Russia, West Siberia, the Russian Far East. Europe (ranging northward to the Netherlands and Germany); Belarus, Ukraine, Northeast China.

Note. Shevkunova and Gracheva (1961) reported Culiseta ochroptera from AP but did not specify the exact collection locality. Since AP is a vast territory, we have not mapped this record in Fig. 12.

Culiseta (Culiseta) alaskaensis (Ludlow, 1906)

Material. MP, RK, SPb, LP, Komi (Fig. 13).

Fig. 13.
figure 13

Collection localities of Culiseta alaskaensis (Ludlow) in Northwestern Russia. Designations as in Fig. 3.

Distribution. MP (Shingareva, 1926; Gutsevich, 1934; Solovei and Likhoded, 1966; Tamarina and Aleksandrova, 1974; Sharkov, 1976, 1980a). AP (Edwards, 1921; Stackelberg, 1937; Sharkov, 1982). NAO (Monchadsky, 1950). RK (Shingareva, 1926; Natvig, 1948; Lobkova, 1956; Lobkova and Makarova, 1961; Jakovlev et al., 2014). SPb (Gutsevich, 1948; Fedorov, 1969). LP (Natvig, 1948; Taldrik, 1967). VP (Adrianov, 1953; Sharkov, 1982; Belova et al., 2008). Komi (Belokur, 1960; Beltyukova and Mitrofanova, 1971; Bryushinina, 1971; Potapov et al., 1972; Ostroushko, 1986; Panyukova and Ostroushko, 2017). KP (Bernotiene, 2012). PP (Medvedev and Matov, 1999). NP (Panyukova and Medvedev, 2008).

Norway (Natvig, 1948; Mehl, 1996). Sweden (Natvig, 1948; Schäfer and Lundström, 2001; Lundström et al., 2013; Möhlmann et al., 2017). Finland (Natvig, 1948; Utrio, 1977; Culverwell, 2018; Culverwell et al., 2021). Estonia (Remm, 1957). Latvia (Spungis, 2000). Lithuania (Pakalniskis et al., 2006).

European Russia, Siberia, the Russian Far East. Europe (ranging northward to the UK and the Netherlands); Belarus, Ukraine, Moldova; North America.

Culiseta (Culiseta) annulata (Schrank, 1776)

Material. SPb, LP, KP (Fig. 14).

Fig. 14.
figure 14

Collection localities of Culiseta annulata (Schrank) in Northwestern Russia. Designations as in Fig. 3.

Distribution. SPb (Gutsevich, 1948; Fedorov, 1969). PP (Medvedev and Matov, 1999). NP (Panyukova and Medvedev, 2008).

Norway (Natvig, 1948; Mehl, 1996). Sweden (Natvig, 1948; Dahl, 1975; Schäfer and Lundström, 2001; Lundström et al., 2013; Möhlmann et al., 2017). Finland (Utrio, 1977; Culverwell, 2018; Culverwell et al., 2021). Estonia (Remm, 1957). Latvia (Spungis, 2000). Lithuania (Pakalniskis et al., 2006).

European Russia (west and northwest), Siberia, the Russian Far East. Europe (ranging northward to the UK, Belgium, and Denmark); North Africa, Belarus, Ukraine, Moldova, Transcaucasia, Asia Minor, Kazakhstan, Middle Asia.

Culiseta (Culiseta) bergrothi (Edwards, 1921)

Material. MP, RK, SPb, LP, Estonia (Fig. 15).

Fig. 15.
figure 15

Collection localities of Culiseta bergrothi (Edwards) in Northwestern Russia. Designations as in Fig. 3.

Distribution. MP (Shingareva, 1926; Stackelberg, 1937; Rumsh, 1948; Solovei and Likhoded, 1966; Tamarina and Aleksandrova, 1974; Sharkov, 1980a, 1980b). AP (Sharkov, 1982). RK (Lobkova, 1956; Jakovlev et al., 2014). VP (Sharkov, 1982; Belova et al., 2008). Komi (Ostroushko, 1986; Panyukova and Ostroushko, 2017). PP (Medvedev and Matov, 1999).

Norway (Natvig, 1948; Mehl, 1996). Sweden (Natvig, 1948; Schäfer and Lundström, 2001; Lundström et al., 2013; Möhlmann et al., 2017). Finland (Natvig, 1948; Utrio, 1977; Culverwell et al., 2021). Estonia (Maslov, 1967).

European Russia (north and west), Siberia, the Russian Far East. Europe (Denmark), Kazakhstan, Mongolia, North China, Korea, Japan.

Coquillettidia richiardii (Ficalbi, 1889)

Material. RK, SPb, LP, PP, NP (Fig. 16).

Fig. 16.
figure 16

Collection localities of Coquillettidia richiardii (Ficalbi) in Northwestern Russia. Designations as in Fig. 3.

Distribution. RK (Lobkova, 1956; Jakovlev et al., 2014). SPb (Gutsevich, 1948; Fedorov, 1969). LP (Taldrik, 1967). Komi (Panyukova and Ostroushko, 2017). KP (Levenson et al., 1959; Bernotiene, 2012). PP (Medvedev and Matov, 1999). NP (Fedorova, 1977; Panyukova and Medvedev, 2008).

Norway (Mehl, 1996). Sweden (Natvig, 1948; Schäfer and Lundström, 2001; Lundström et al., 2013; Möhlmann et al., 2017). Finland (Natvig, 1948; Utrio, 1977; Culverwell, 2018; Culverwell et al., 2020). Estonia (Remm, 1957). Latvia (Spungis, 2000). Lithuania (Pakalniskis et al., 2006).

European Russia, West Siberia. Europe (ranging northward to the UK, Belgium, and Denmark); North Africa, Belarus, Ukraine, Moldova, Asia Minor, Kazakhstan, Middle Asia.

DISCUSSION

Analysis of additional publications has allowed us to correct the mosquito check-list in NWR, currently comprising 47 species; the list was supplemented with Anopheles atroparvus, recorded in KP (Levenson et al., 1959). In the course of the examination of the records of species of the genera Anopheles, Coquillettidia, Culex, and Culiseta in comparison with the SAT parameter, the minimal SAT values for each species within NWR were determined (Table 2) and the position of the northern range boundaries of these species was analyzed. Based on our material and the ZIN collections, the northern distribution boundaries in NWR were updated for five species: Anopheles claviger, A. messeae, Culiseta morsitans, Culex territans, and C. modestus. Based on the minimal SAT values, species of the genera Anopheles, Coquillettidia, Culex, and Culiseta were included in four groups (Fig. 17).

Group 1. Three species: Culex pipiens, Culiseta alaskaensis, and C. bergrothi. These species are distributed in the area with SAT values exceeding 770°C (i.e., the whole territory of NWR excluding the north and east of NAO and the insular part of AP; see Fig. 17). No species of the genera Anopheles, Coquillettidia, Culex, and Culiseta have been reliably recorded in the territories of NWR with SAT values below 770°C.

Fig. 17.
figure 17

Distribution of groups of Culicidae species in Northwestern Russia. The composition of groups 1–4 is explained in the text.

Group 2. Nine species, including 3 species of group 1 and also Anopheles beklemishevi, A. maculipennis, A. messeae, Culex territans, Culiseta morsitans, and C. ochroptera. These species are distributed in the area with SAT values exceeding 1227°C (i.e., the territory of NWR excluding the greatest parts of MP and NAO and the north and east of the Komi Republic; see Fig. 17). The northernmost locality of Culiseta morsitans differs considerably from those of the remaining species in a lower SAT value (see Table 2). The records with SAT 1577.2°C are probably located near the northern distribution boundary of Anophelinae mosquitoes in NWR; as compared with this value, the record of an Anopheles mosquito in MP (Shuioniioki River, SAT 1136.4°C) is quite unexpected.

Table 2. Minimal values of the sums of active temperatures above 0°C for mosquito species in Northwestern Russia

Group 3. Thirteen species: all the examined species excluding Anopheles atroparvus, Culex modestus, and Culiseta annulata. Mosquitoes of this group are distributed in the area with SAT values exceeding 1733°C (KP, LP, south of RK, AP, Komi, VP, PP, and NP). Coquillettidia richiardii is the only species of its genus in the North Palaearctic; correspondingly, the locality with a SAT value of 1966.7°C probably lies at the northern distribution boundary of the genus Coquillettidia in NWR.

Group 4. Sixteen species: all the species studied here. They are distributed in the area with SAT values exceeding 2112°C: KP, south and west of LP, PP, most of NP, and south of VP. For instance, Culex modestus was found in the south of VP (SAT 2112.3°C and higher), and Culiseta annulata was recorded in SPb (SAT over 2226.4°C). Anopheles atroparvus was the most thermophilous of all the 16 species in the NWR fauna: it was found only in the west of KP (SAT over 2721.8°C).

Mosquitoes are amphibiotic insects whose larvae and pupae develop in temporary and permanent water bodies, while the adults are terrestrial. The larvae and adults of most mosquito species are not trophically specialized to any plant or animal species; therefore, the ranges of species of the family Culicidae do not directly follow those of other organisms. The distribution of some mosquito species may be limited by the presence of water bodies suitable for their larvae. NWR occupies a large territory with a total area of over 1.5 mln km2, diverse climatic conditions, and a wide range of ecozones, from Arctic deserts to mixed forests. At the same time, in NWR there are no large arid or highland regions which could prevent the spreading of mosquitoes. Consequently, the SAT value in the collection locality appears to be an adequate climatic parameter reflecting the main features of the life cycle of mosquito species.

NWR includes some territories with relatively well-studied faunas of mosquitoes (e.g., MP, RK, SPb, and Komi) and also regions poorly studied in this respect (KP, AP, and NAO). In some cases, comparison of the northern distribution boundaries and the corresponding SAT values may be used to extrapolate the range boundary onto still unstudied territories. For example, the records of Culiseta bergrothi in the north of MP and the northeast of Komi (SAT 848.3°C) indicate that the species may be distributed over the largest part of NAO and AP. The records of Culiseta morsitans in MP and Komi (SAT 1227.8°C) indicate that the species may also occur in the continental parts of AP and VP, while the records of Coquillettidia richiardii in RK and Komi (SAT 1966.7°C) suggest its presence in VP.

The northward expansion of a mosquito species may be limited not only by the number of days with a temperature sufficient for its preimaginal development and adult activity, but also by the low winter temperatures eliminating the insects during diapause. Most mosquitoes distributed in the high latitudes of the Holarctic (e.g., Aedes species) overwinter in the egg stage, but the northernmost species considered herein, Culiseta alaskaensis and C. bergrothi, diapause as adult females; yet this feature does not prevent them from spreading as far northwards as the Barents Sea coast.

CONCLUSIONS

Comparison of the species records and the SAT values for the collection localities was used to extrapolate the northern distribution boundaries of mosquito species in NWR. The northern range boundaries in different mosquito species were found to vary significantly within the NWR territory, corresponding to the SAT values from 775.5 to 2721.8°C. For instance, the northern range boundaries of the closely related species Culiseta alaskaensis and C. annulata are located far apart: in the north of MP and Komi (SAT 775.5°C) in the former and in SPb (SAT 2226.4°C) in the latter. The mosquito species present in NWR can be included in four groups according to the common trends in their distribution. For example, the northernmost localities of mosquitoes from different genera: Culiseta fumipennis and Coquillettidia richiardii, and also Culex territans and Anopheles messeae, have nearly identical SAT values: from 1951.0 to 1966.7°C and from 1577.2 to 1587.1°C, respectively.

The results of this research may be used for species distribution modelling of such important vectors as Anopheles maculipennis, A. messeae, Culex pipiens, C. modestus, and Coquillettidia richiardii.