A checklist of scale insects recorded to date in Poland is presented. The data provided here are based on literature records and include the latest taxonomic and nomenclatural changes and updates on Coccomorpha reported in Poland. Changes in comparison with ScaleNet and Fauna Europaea electronic databases are also discussed. A total of 185 species belonging to 98 genera and 16 families are included in the list. Of this group, 47 species are alien introduced species and live only indoors, and one species, Pulvinaria floccifera (Westwood), develops both indoors and outdoors.

Coccoids, native and alien species, validation source

Scale insects form a relatively small group of insects in the Polish fauna and represent only approximately 0.7% of the 27,000 insect species currently known in Poland. However, a few species are identified as pests of economic importance, and especially, in recent years, the invasion of alien scale insects has been observed in several parts of Poland (Łagowska et al. 2015, 2018; Golan et al. 2017).

Scale insects have been known for centuries in Poland for the carmine dye extracted from the Polish cochineal scale Porphyrophora polonica (Linnaeus). The presence of P. polonica in Poland was reported for the first time in the 16^th century (Miechowita 1521) and information about the harmful scale insects was published in later years by some authors (Trzebiński 1916; Ruszkowski 1925, 1933; Minkiewicz 1926). Advanced studies on the scale insect fauna of Poland were initiated by Kawecki, whose results have been presented in numerous publications from 1935 to 1985. In the same period and later, Koteja and Koteja and Żak-Ogaza, in publications from1964 to 2000, extensively studied the Coccomorpha and greatly contributed to the knowledge of the scale insect fauna in Poland. Further contributions are due to the studies by Komosińska (1961-1987), Komosińska and Podsiadło (1967), Dziedzicka (1970-1990), Podsiadło (1975); Podsiadło and Komosińska (1976), Łagowska (1990-2005), Łagowska and Koteja (1996), Dziedzicka and Karnkowski (1999), Łagowska and Golan (2005) and Łagowska et al. (2015, 2017, 2018).

Finally, 90 native and greenhouse species of scale insects that were new to the Polish fauna were discovered in the years 1961–1980 (Koteja 1985; Łagowska and Golan 2005). However, the records of species new to the Polish fauna significantly decreased from 32 in the period 1971–1980 to 8 in 1991–2005 (Łagowska and Golan 2005), and only another 8 new species were recorded in Poland in 2006-2019.

The early data on the distribution of scale insects in Poland were summarized by Kawecki (1985) in a catalogue listing 170 species, including 34 indoor species, and 11 records of misidentified species or species for which no host plants or localities were given. Later, two checklists of scale insects in Poland were presented by Koteja (1996) and Łagowska (2004) who reported 184 and 185 species respectively, each including 44 indoor species. In addition, an annotated list of alien scale insects present in Poland was published by Łagowska et al. (2015).

Two electronic databases provide important world-wide information on scale insect distribution: the Fauna Europaea (FaEu) database (Burckhardt 2013), which reports 163 species of scale insects from Poland, and the ScaleNet database (García Morales et al. 2016), which lists 177 species. Since the last checklist (Łagowska 2004), several new records of scale insects from Poland have been published (Łabanowski 2009; Kalandyk and Węgierek 2010; Kozár et al. 2013; Łagowska et al. 2015, 2018). In the meantime, the nomenclature of the scale insects has also been partially changed. Moreover, several records reported in FaEu and ScaleNet databases were regarded as doubtful or erroneous and need revision. The present paper provides a comprehensive revised list of the scale insects of Poland with updated nomenclature and references to the first reliable Polish records of each species. In addition, discrepancies between the present list and the last checklist (Łagowska 2004) as well as differences from the records reported in the FaEu and ScaleNet databases are discussed.

The aim of the present checklist is to provide baseline reliable data for future faunistic and taxonomic studies.

The list presented in this paper is based on the literature records of Coccomorpha in Poland available up to September 2019. A reference to the first reliable record of each species is included. Fossil species of scale insects and those that have been intercepted only once on imported plant materials are excluded. Families and species within each family are listed in alphabetical order according to the classification used in the ScaleNet database (García Morales et al. 2016). The references to species recorded in Poland reported in FaEu and ScaleNet have been checked and, if erroneous, corrected in the present lists. Changes in systematic status and synonymies, mostly proposed by Kozár et al. (2013) and Danzig and Gavrilov-Zimin (2014, 2015), and presently accepted in ScaleNet database, have been adopted in the present list. Scale insect species recorded in Poland are listed in Table 1. They belong to four categories as follows: (i) native species; (ii) alien species established outdoors; (iii) alien species established indoors; and (iv) alien species that can live and develop both outdoors and indoors. The definition of alien species in this paper is the one proposed by Łagowska et al. (2015).

At the present time the Polish scale insect fauna comprises a total of 185 species, distributed in 98 genera and 16 families. The Pseudococcidae are the most numerous family, with 50 recorded species, followed by Diaspididae (48 species), Coccidae (43 species), and Eriococcidae (sensu lato) (18 species) (Table 1). The remaining 12 families are each represented by 1–5 species. The ratio of species to genera differs between families. The highest ratio (2.6:1) is in the Eriococcidae, followed by Coccidae (2.3:1), Diaspididae (2.0:1), and Kermesidae (2.0:1) (Table 2). The ratio of species number per genus in the Pseudococcidae family is 1.8:1, which is close to the general mean ratio of 1.9:1 reported for Poland (Table 2).

Of the 185 species present in Poland, 133 (71.9%) are native (Figure 1). The alien scale insect species number 52 (28.1% of total); these species clearly dominate over the native ones in the Diaspididae family, while the remaining families are represented by 1–10 alien species or only by native species (Figure 1). Of the 52 alien species known in Poland, 47 can develop only indoors, while five, namely Aulacaspis rosae, Comstockaspis perniciosa, Parthenolecanium fletcheri, Pulvinaria floccifera, and P. hydrangeae, overwinter and develop outdoors. Pulvinaria floccifera develops both indoors and outdoors (Table 1).

Figure 1. 

Native and alien scale insect species in different families in Poland.

The scale insect species recorded in Poland represent only ca. 7.3% of the 2536 species known in the Palearctic region (García Morales et al. 2016) and ca. 41.1% of the 450 species reported in Europe (Pellizzari and Germain 2010). The previous checklist of scale insects of Poland was published 15 years ago (Łagowska 2004) and listed 185 species distributed in nine families and 94 genera. In the present list, the families Cryptococcidae, Matsucoccidae, Monophlebidae, Steingeliidae, Xylococcidae, Putoidae, and Rhizoecidae have been added, using the currently accepted classification of Coccomorpha. Moreover, eleven species new for the country have been added and ten species removed. The new entries are: Asterodiaspis quercicola, Pulvinaria hydrangeae, P. regalis, Aspidiotus palmarum, Aulacaspis yasumatsui, Lepidosaphes tokionis, Acanthococcus macedoniensis, Icerya purchasi, Spilococcus mamillariae, Volvicoccus volvifer, and Rhizoecus americanus. Of these V. volvifer, P. hydrangeae, P. regalis, and A. macedoniensis are established outdoors (Kalandyk and Węgierek 2010; Kozár et al. 2013; Łagowska et al. 2018), whereas A. yasumatsui, L. tokionis, S. mamillariae, and R. americanus, are indoors species (Łabanowski 2009). Icerya purchasi and A. palmarum were overlooked in the previous checklist and are therefore added to the present one. Asterodiaspis quercicola is here considered as a valid species (García Morales et al. 2016), despite the fact that Podsiadło (1990) and Stumpf and Lambdin (2006) considered A. quercicola and A. variolosa as synonyms.

Of the ten species removed from the list, six have been synonymized with other species (Eulecanium slavum (Kawecki, 1961), Lepidosaphes oleae Leonardi, 1908, Heliococcus danzigae Bazarov, 1974, Trionymus isfarensis Borchsenius, 1949, T. singularis Schmutterer, 1952, and Phenacoccus evelinae Tereznikova, 1975). The presence in Poland of the other four species removed from the list, Ripersia corynephori Signoret, 1875, Carulaspis visci (Schrank, 1781), Fiorinia fioriniae (Targioni-Tozzetti, 1867) and Oceanaspidiotus spinosus (Comstock, 1883) is here considered as doubtful or erroneous. Kiritchenko (1940) listed R. corynephori as found near Warsaw, but Kawecki (1985) assumed that this record was incorrect and the species might be a misidentification of Pseudococcus parvus Borchsenius, 1949 (now Mirococcopsis subterranea (Newstead, 1893)). Similarly, the record of C. visci was very likely incorrect and the species may be a misidentification of Carulaspis juniperi (Bouchѐ, 1851). In addition, the records of F. fioriniae and O. spinosus are questionable because no host plants or localities were given in the list published by Czyżewski (1937). All the species mentioned above have not been collected again since they were first recorded.

Based on the distribution data reported by Łagowska (2001), the native species currently known from Poland are all Palearctic. Almost half of them are widely distributed in this region, and relatively few are known only from three or four countries. This latter group includes the following species: Anophococcus confusus, Rhizococcus cantium, Boreococcus ingricus, Mirococcus festucae, and A. macedoniensis. Two species, Parthenolecanium smreczynskii and Kiritshenkella lianae, are known so far only from Poland and are possibly endemic.

Recently, much attention has been paid to the alien species of scale insects that have been introduced or have spread into Poland. This group includes 47 indoor and five outdoor species. One species (P. floccifera) has been recorded on ornamental plants in greenhouses in Poland as well as on outdoor ornamentals, mostly on Ilex sp., and appears to be established (Łagowska et al. 2017). Of the 47 species established indoors, 29 (61.7%) belong to the Diaspididae. This high proportion of species from Diaspididae family introduced into Poland is similar to the results presented by Pellizzari and Germain (2010) for Europe. According to these authors, the 60 alien species belonging to the Diaspididae account for nearly half (44.6%) of the 130 alien species estimated to occur in Europe. Of the five alien species established outdoors in Poland, only C. perniciosa and P. floccifera are considered as invasive (Łagowska et al. 2017, 2018). Currently, C. perniciosa poses the greatest threat, affecting a number of fruit trees in Poland (Golan et al. 2017).

Some differences in the species richness were found between the data reported in the databases ScaleNet and FaEu and the present checklist. Scale insects that are erroneously recorded as present in Poland in the above recorded databases are discussed below: