Psocids ( Psocoptera ) Chapter 13 . 2

Abstract Among the 231 species of Psocoptera present in Europe, 49 (21.2%) are considered to be of alien origin. Th ey include 29 exotic introduced species and 20 cryptogenic species. Most of the exotic species originated from tropical and subtropical areas, essentially from Africa. Many of them are food pests, moving along with stored products. Th irty-nine of these species occur in buildings in Europe.


Introduction
Psocoptera (commonly called psocids) are one of the smaller orders of paraneopteran insects.Many species are arboreal, but a few are more usually found on low vegetation or in litter.All feed on microfl ora and organic debris.Some are found in nests of birds and mammals, within aggregations of other insects or associated with human habitations.Th e head of these usually soft bodied pterygote insects (with a body length of 0.67 mm to 8 mm) is globulous with an usually prominent clypeus and projecting eyes, long and fi liform antennae and biting mouthparts, the laciniae being characteristic for the order.Adults have usually four wings with simple venation.However, many species are brachypterous, micropterous or apterous (Lienhard 1998, Lienhard and Smithers 2002, Mockford 1993, New 2005).
Lepidopsocidae: Adult wings of lepidopsocids, which belong to the family group Atropetae, are generally pointed apically when fully developed.Body and forewings are generally covered with scales, but occasionally with dense setae Mockford 1993.Th e fi ve species found in Europe are all alien.
Trogiidae: Species in this family, which belongs to the family group Atropetae, are apterous, micropterous or brachelytropterous.Body and forewings lack scales and dense setae.Four of the 19 species found in Europe are cryptogenic (21%).Th ese four species are brachelytropterous, presenting short, leathery winglets similar to short elytra.Th eir habitats are associated with humans, e.g.within buildings and glasshouses (Lienhard 1998, Mockford 1993).
Psoquillidae: Body and forewings of species in this family, which also belongs to the family group Atropetae, do not bear scales.Th e three species currently found in Europe are not believed to be native, two of them being with certainty of alien origin and the third cryptogenic.All occur within buildings in Europe.
Psyllipsocidae: Th is family belongs to the family group Psocatropetae.Th e fi ve species found in Europe (100%) are either alien (Baz 1990) or cryptogenic species (Baz 1988).All are usually found in buildings and glasshouses in Europe.
Liposcelididae: Th ese psocids belong to the family group Nanopsocetae.Th ey are characterised by a fl attened body and antennae with secondary annulations on their fl agellum.Fourteen species out of the 39 (36%) found in Europe are either aliens (Broadhead 1950) or cryptogenic species (Broadhead 1954b).Th ey include exclusively apterous species, all of which being occur in buildings.
Pachytroctidae: Th e body shape of the species of this family, which belongs to the family group Nanopsocetae, is not fl attened dorsoventrally and the basal fl agellar segments are not secondarily annulated (New 2005).Only three species live in Europe, and two of them are not natives (67%).
Caeciliusidae: Th is family belongs to the family group Caeciliusetae and to the superfamily Caecilioidea.Th e species are characterised by the presence of at least one, or more commonly two or three, ventral abdominal vesicles (Mockford 1993).Th e family was once named Caeciliidae, but the latter name was changed because of homonymy with a family of amphibians (Lienhard 1998).Only one species out of the 15 (7%) found in Europe is cryptogenic.Lacroixiella martini, is only known by the two syntypes collected by Lacroix in 1918 in a french military hospital (Lacroix 1919).
Lachesillidae: Th ese psocids belong to the family groupe Homilopsocidea.Th e species have an areola postica* in their forewings characterized by a very sparse and short ciliation on its veins and margin.Th e lacinial* tip of the Lachesillidae is slender and bicuspid * (Lienhard 1998, Mockford 1993).Two species out of the 12 found in Europe are aliens (17%).
Ectopsocidae: Members of this family, which belongs to the family group Homilopsocidea, are characterised by the absence of an areola postica in their wings such as in the family Peripsocidae.Ten out of the 14 species found in Europe (71%) are either alien (Broadhead 1950) or cryptogenic species (Baz 1988).Six of these species are found occurring within buildings, either regularly (Baz 1990) or sometimes (Baz 1990), compared to only one of the 4 native species.
Peripsocidae: Species of this family, which also belongs to the family group Homilopsocidea, are also characterised by their absence of an areola postica in their wings.Peripsocus bivari is the only alien among nine species found in Europe (11%).Elipsocidae: Veins and wing margins of species in this family, which also belongs to the family group Homilopsocidea, bear setae but the hindwing marginal setae are limited to the radial fork (New 2005).Propsocus pulchripennis, occurring out-of-doors in France, Great Britain and Madeira, is the only alien among 24 species found in Europe (4%).Th e native range of this widespread species is the coastal regions of subtropical countries (Lienhard 1998, Lienhard andSmithers 2002).
Psocidae: Th is family belongs to the family group Psocetae.Its members are easily recognised by their wing venation, where the areola postica is fused to the M-vein.Th e Psocidae fauna of Europe includes 34 species but Trichadenotecnum innuptum is the only alien among them (3%).

Temporal trends of introduction in Europe of alien psocids
Th e cryptogenic species Trogium pulsatorium was already known as Termes pulsatorium in the 10th edition of Systema Naturae by Linnaeus in 1758 (Linnaeus 1958).From 1850 to 1874, three other cryptogenic species and the alien Psoquilla marginepunctata were recorded from Europe.One alien and one cryptogenic species followed in 1899.In the 20th century, seven species on our list were recorded for the fi rst time in Europe from 1900 to 1924, 18 from 1925 to 1949, seven from 1950 to 1974 and fi nally ten from 1975 to 1999.In the 21st century, no new alien has arrived in Europe to date.

Biogeographic patterns of the Psocoptera species alien to Europe
Th e distribution status is only known for 29 species out of 49, 40.8% being thus considered as cryptogenic.Figure 13.2.2details the probable regions of origin.Most species appear to originate from Africa (9 species, 18.4 %), far beyond the other continents but for seven species (14.3%) we only know that they arrived from tropical and subtropical regions.Central and Western Europe appear to be more colonized by alien psocids (Figure 13.2.3).

Figure 13
Figure 13.2.1.Taxonomic overview of the Psocoptera species alien to Europe compared to the native fauna.Species alien to Europe include cryptogenic species.Families are listed in a decreasing order based on the number of alien species.Th e number over each bar indicates the number of species observed per family.

Figure 13
Figure 13.2.2.Geographic origin of the Psocoptera species alien to Europe.Numbers indicate the relative proportion of alien species originating from a given region.

Figure 13
Figure 13.2.3.Colonization of continental European countries and main European islands by the Psocoptera species alien to Europe.Archipelago: 1 Azores 2 Madeira 3 Canary islands.