The Twisted-Wing Insects (Strepsiptera) of South-Eastern Belarus

: An overview of the twisted-wing insects for the South-Eastern Belarus is provided. Our own researches (2016 – 2021) of species compositions of the twisted-wing insects in South-Eastern Belarus were executed in different biotopes on the territory of Gomel area. Five species from two families – Hylecthrus rubi Saunders, 1850, Stylops hammella Perkins, 1918, S. melittae Kirby, 1802, S. thwaitesi Perkins, 1918 and Paraxenos sphecidarum (Dufour, 1837) – have been recorded. Collection data for each species are presented and their known distribution and biology briefly discussed.


Introduction
Members of the order Strepsiptera display highly peculiar morphology and lifestyles. They are small to medium sized insects (1.0-7.5 mm long) exhibiting extreme sexual dimorphism [1,2]. Free living and flying males have twisted hind wings, while their fore wings are reduced to clublike appendages. Usually endoparasitic and wingless females are known to colonize members of seven insect orders [2,3]. Approximately 600 Strepsiptera species are known to exist globally [4,5], while 30 species from 7 families are known in Europe [6,7].
The order Strepsiptera in Belarus hasn't been studied, data on the record of one species Stenocranophilus anomalocerus Pierce, 1918 from the family Halictophagidae, parasitoid of Liburnia Stеl, 1866 (Hemiptera: Delphacidae), has been published previously [8]. Continuing the research, 3 more species of twisted-wing insects have been found in Belarus [9][10][11]. The present study aims to summarize and contribute new data to the already published results.

Materials and Methods
The materials were obtained by the author using standard collection methods on the territory of Gomel (the main research), Bragin and Loev districts of Gomel area during the field seasons of 2016-2021. An analysis of these collections made it possible to provide new faunistic information about 5 species of twisted-wing insects. The asterisk marks the species first discovered on the territory of Belarus.    [14,15]. Information about the nature of their stylization is presented in Table 1.  [20]. Perkins, 1918  2. Belarus, Gomel area, Gomel district, grassy slope on the edge of the sand quarry near Uza village, on the inflorescences of Solidago canadensis L., 52°22'57"N, 30°52'45"E, 122 a.s.l., 12.08.2017 -1♂ of A. sabulosa stylopized by 2♀ of P. sphecidarum (1♀ between IV and V tergites on the left and 1♀ between V and VI tergites in the middle).
Information about the nature of their stylization is presented in Table 2. Table 2. The character of stylopization of the studied specimens of A. sabulosa by the strepsipteron P. sphecidarum from the population of the Kirovo village in the Bragin district of the Gomel area.

Number of Parasites Their Localization between the Abdominal Segments of the Host Wasp
The remains of ♂ puparium between V and VI tergites on the right The remains of ♂ puparium between IV and V tergites on the right, ♀ between VI and VII tergites on the left ♂ 1 ♂ puparium between IV and V sternites in the middle ♀ 1 ♂ puparium between IV and V tergites on the left ♀ 2 ♀ between V and VI tergites on the right, ♀ between III and IV sternites in the middle ♀ 1 The remains of ♂ puparium between IV and V tergites on the right ♀ 1 ♀ between IV and V tergites on the left ♂ 1 ♂ puparium between V and VI sternites on the left ♂ 1 The remains of ♂ puparium between IV and V tergites on the left ♂ 1 The remains of ♂ puparium between IV and V tergites on the left ♂ 1 ♀ between IV and V tergites on the right ♀ 4 ♀ between III and IV tergites on the right, ♀ between IV and V sternites on the left, 2♀ between V and VI tergites on the sides The remains of ♂ puparium between V and VI tergites on the right, ♀ between IV and V tergites on the left ♀ 3 The remains of ♂ puparium between III and IV tergites on the left, ♀ between IV and V tergites on the left, ♀ between V and VI tergites on the right ♂ 1 The remains of ♂ puparium between IV and V tergites on the right The remains of 2♂ pupariums between IV and V tergites on the sides ♂ 1 The remains of ♂ puparium between IV and V tergites on the right ♀ 3 The remains of ♂ puparium between IV and V tergites on the left, ♀ between V and VI tergites on the right, ♂ puparium between VI tergite and VI sternite above the sting ♀ 1 The remains of ♂ puparium between V and VI tergites on the left ♂ 1 ♀ between V and VI tergites in the middle 4. Belarus, Gomel area, Bragin district, pine forest on the dunes with adjacent farmland and a dense network of reclamation channels between Asarevichi and Grushnoe villages, on dry meadow-steppe areas of a sandy slope with low grass vegetation, 51°37'22"N, 30°25'52"E, 106 a.s.l., 18.08.2019 -1♀ of A. sabulosa stylopized by 1♂ of P. sphecidarum (♂ puparium between IV and V tergites on the right) and 1♀ of A. sabulosa stylopized by 1♂ and 1♀ of P. sphecidarum (the remains of ♂ puparium between IV and V sternites on the right and ♀ between IV and V tergites on the right).

Discussion
It is quite obvious that the taxonomy of Strepsiptera is far from resolved. In genus Stylops additional name-changes are expected. In order to resolve the exact species delimitations molecular analyses are needed. Apart from the taxonomical uncertainties there are also a species of twisted-wing insects that are still expected to turn up in the Belarus because their hosts do occur here and are sometimes even quite common.

Conclusions
Thus, as a result of the studies carried out on the territory of the southeast of Belarus, five species of twisted-wing insects were identified, among which Stylops hammella Perkins, 1918 and S. thwaitesi Perkins, 1918 are new to the strepsipterofauna of the Republic.
Since the material identified is small, and there is no published data on the fauna of twisted-wing insects in Belarus and neighboring countries, this study can be considered to be only a preliminary overview. Further study is planned for the future, and an expansion of the species list of twisted-wing insects in Belarus is to be expected.

Conflicts of Interest:
The author states that he has no conflict of interest.