Aphids ( Hemiptera , Aphididae ) Chapter 9 . 2

Abstract Our study aimed at providing a comprehensive list of Aphididae alien to Europe. A total of 98 species originating from other continents have established so far in Europe, to which we add 4 cosmopolitan species of uncertain origin (cryptogenic). Th e 102 alien species of Aphididae established in Europe belong to 12 diff erent subfamilies, fi ve of them contributing by more than 5 species to the alien fauna. Most alien aphids originate from temperate regions of the world. Th ere was no signifi cant variation in the geographic origin of the alien aphids over time. Th e average introduction rate was 0.5 species per year since 1800. Th e mean number of newly recorded species per year decreased since 2000 but this pattern may change in the following years.


Introduction
About 4700 species of Aphididae have been described worldwide (Remaudière and Remaudière 1997).About one third of these species are present in Europe.As for many other taxonomic groups, very few checklists of alien Aphididae have been available for Europe until recently.In 2002, Geiter et al. (2002) published a list of 131 species considered non-indigenous in Germany and Nobanis (2005) listed 34 species of nonnative Aphididae in its geographic area in 2005.Lampel and Gonseth (2005) listed 37 species alien to Switzerland in 2005 whilst Rabitsch and Essl (2006) listed 40 alien aphid species from Austria in 2006.Th e diff erences in the number of species considered non-indigenous clearly refl ect diff erences in the composition of the fauna of each country, but also refl ect diff erences in the defi nition of 'alien'.Lampel and Gonseth (2005) considered only species of non-European origin whereas Geiter et al. (2002) included all species considered non-native to Germany.
Th e goal of this work is to provide a fi rst comprehensive list of Aphididae alien to Europe.Aphid species originating from one European country and introduced into another, i.e. species alien in Europe such as Diuraphis noxia (Kurdjumov, 1913) and Brachycorynella asparagi (Mordvilko, 1929), will not be considered in this work.Th ese species may have an invasive status in the area where they were introduced but it appeared diffi cult to disentangle human-mediated introductions from natural expansion.
To defi ne the species present in Europe, we used the list of European Aphididae elaborated by Nieto Nafria for Fauna Europaea (Nieto Nafria et al. 2007).We compiled information about each species from published sources and experts to defi ne their origin, i.e.European vs non-European.Among the references consulted, the lists cited above and the three comprehensive books by Blackman & Eastop (Blackman and Eastop 1994, 2000, 2006) proved to be particularly useful.Once a fi rst list of alien aphids had been defi ned, we sought additional information, such as the date of fi rst occurrence in Europe.June 2008 was the cut-off date for our literature survey.All the information collected for the 102 species considered is provided in Table 9.2.1.

Taxonomy of alien species
Th e delineation o f the taxa included under the family name Aphididae has varied over the last 50 years.Here, we use Aphididae sensu Eastop and Hille Ris Lambers (1976) and Remaudière and Remaudière (1997).Th erefore, we did not consider Adelgidae and Phylloxeridae in this chapter.Taxonomy and nomenclature are as described by Remaudière and Remaudière (1997), Nieto Nafria et al. (1998), Quednau (1999Quednau ( , 2003)), and Eastop and Blackman (2005).Some of the names cited in published studies could not be clearly attributed to a currently valid taxon and were therefore excluded.
A total of 98 species present in Europe but originating from another continent have been listed to date, to which we can add four cosmopolitan species of uncertain origin (cryptogenic) (Table 9.2.1).For comparison, the European aphid fauna currently includes 1,373 species (Nieto Nafria et al. 2007), meaning that 7.4 % of the European aphid fauna is of alien origin.
Th e 102 alien species of Aphididae established in Europe belong to 12 diff erent subfamilies, most of which are already represented among the native entomofauna (Figure 9.2.1).However, three subfamilies (Greenideinae, Lizerinae and Neophyllaphidinae) were not known in Europe before introductions.Each of these three subfamilies is represented by a single species.Greenidea fi cicola is a member of the Greenideinae subfamily widespread in eastern regions and living on several species of Ficus.It was introduced into Italy in 2004 and seems to be widespread in Southern Europe (Italy, Spain and Malta) (Barbagallo et al. 2005a, Mifsud 1998).Paoliella eastopi, a species belonging to the Lizerinae described from Kenya, has only been found in one European country, England.All Paoliella species are of African origin.Neophyllaphis podocarpi, the only Neophyllaphidinae species known in Europe, originates from Asia and was recorded on Podocarpus in Italy in 1990 (Limonta 1990) but appears to have spread.Five subfamilies contribute more than fi ve species to the alien fauna (Figure 9.2.1).Th e subfamily Aphidinae predominates, accounting for 59% of the alien Aphididae, followed by Calaphidinae (16%), Lachninae (5.8%), Eriosomatinae (4.8%) and Chaitophorinae (4.8%).Th ese fi ve subfamilies are also the most species-rich in native species.Each of the other seven subfamilies accounts for less than 1% of the alien Aphididae (Figure 9.2.1).Th e Hormaphidinae is the only subfamily represented by more alien than native species (4 species vs 1).
Th e taxonomic composition of the alien entomofauna is highly diverse at genus level.Th e 102 alien species belong to 58 diff erent genera (Table 9.2.1).Th irty-two (55%) of these genera are represented in Europe by only non-native species and 40 (69%) contribute only one species to the alien fauna.Th e genus Aphis is the most represented, with eight species.Th is is not surprising, given that this genus contains more than 10% of the world's Aphididae and is abundant in all biogeographical regions of the world.Th is is not the case for another two species-rich genera, the North American Illinoia (seven alien species in Europe and 54 species worldwide) and the Asian Tinocallis (six alien species in Europe and 25 species worldwide).Although the genus Cinara is the second most species-rich genus in the world, with 222 species worldwide, three quarters of which being of non-European origin, surprisingly only three alien species from this genus are present in Europe

Temporal trends
Th e date of the fi rst record in Europe is known, with various degrees of precision, for 94 of the 102 alien aphid species (Table 9.2.1).Th e precise date of arrival is unknown for most species because their introduction was unintentional (see below 9.2.5) and large delays may occur between the date of introduction and the date of reporting.However, in certain cases, introduction is relatively well documented, available data suggesting that the date of the fi rst report was close to the date of introduction.Th is is the case for recent introductions, such as the species detected and monitored by the permanent aerial suction-trap network "Euraphid".Th is system of aphid fl ight surveys, based on a 12.2 m.-high suction trap, was developed by the Rothamsted Experimental Station in the 1960s (Taylor and Palmer 1972).Th is device is now used in several European countries, as part of integrated control networks, and has also proved useful for studies of the long-range dispersal of alates and for the regular detection of aphid species new to the national or European fauna (Hullé et al. 1998).In France, a network of fi ve such traps spread over the territory has been monitoring the aphid species trapped since 1978.Th is system detected four species new to Europe between 1984and 1988(Hullé et al. 1998): Essigella californica (Turpeau and Remaudière 1990), Klimaszewskia salviae (Leclant and Remaudière 1986), Myzocallis walshii (Remaudière 1989), and Tinocallis takachihoensis (Leclant and Remaudière 1986), and has monitored the extension of their geographical range in France.In a very small number of cases, more ancient introductions have also been documented, generally for important pest species.For example, the occurrence of Eriosoma lanigerum, a pest of apple trees originating from North America, was noted for the fi rst time in a nursery in the outskirts of London in 1787 (Balachowsky and Mesnil 1935).Th e species was described by Hausmann in 1802, based on material from Germany, where aphids had been found in nurseries, causing extensive damage.In 1812, the species was found in France, by 1841, it was found in Italy and in 1870 it was reported in Switzerland.E. lanigerum has subsequently spread gradually to all temperate countries of the world (Balachowsky andMesnil 1935, Marchal 1928).
For most alien species, the date of fi rst report sighting may not correspond to the date of introduction and secondary expansion.For example, the pest species Myzus persicae, Panaphis juglandis, and Chromaphis juglandicola were all reported for the fi rst time in Europe between 1800 and 1849, but they were probably introduced long before along with their host plants.Th e primary host of Myzus persicae, the peach tree, grown since classical times in the Mediterranean basin, was imported to Europe from Persia, but probably originated from western China, where it has been cultivated since 5,000 yr BP (Faust and Timon 1995).Th e host plant of Chromaphis juglandidola and Panaphis juglandis, the walnut, may have been introduced to Europe from Persia during the classical era, but this remains a matter of debate (Huntley and Birks 1983).Even for more recent introductions, the time lag between introduction and the fi rst reported sighting may be considerable, particularly if the species concerned is not a pest.Th e date on which a taxonomic group was fi rst recorded is therefore more likely to refer to the period during which it was studied for the fi rst time.Börner between 1930 and1952 made the largest single advance to studies of the aphid fauna of Europe, with the publication of "Europae Centralis Aphid" (Börner 1952).Th is catalysed intensive studies of the aphid fauna in various European countries over the following 20 years.Th e increase in the number of introduced species observed between 1950 and 1974 is partly attributable to this increase in taxonomic and faunistic activity.
Bearing these biases in mind, and taking the fi rst recorded sighting as a proxy for the date of introduction, the mean rate of introduction since 1800 was 0.5 species per year.A similar rate has also been reported for a more recent period (0.42 between 2000 and 2007).Th e number of introductions increased in the second half of the 20th century (Figure 9.2.2).Th e mean number of new records increased from 0.3-0.4 per year before 1950 to more than 1.3 per year between 1950 and 1974.Th e mean number of introductions per year has decreased since 2000, but this pattern may change again in the future.Th e three most recent alien aphid species introduced to Europe are Aphis illinoisensis, a Nearctic species and a pest of vineyards introduced into Crete in 2005 (Tsitsipis et al. 2005), Prociphilus fraxiniifolii, also of Nearctic origin, introduced into Europe in 2003, (Remaudière and Ripka 2003), and Greenidea fi cicola, a tropical species, probably originating from Asia, introduced into Sicily in 2004 (Barbagallo et al. 2005a).

Origin of alien species
A precise continent of origin was ascertained for 90.2% (92 species) of the alien Aphididae species, whereas 5.9% (six species) of the alien species were known only to be native to tropical or subtropical regions and 3.9% (four species) were of unknown origin (cryptogenic,Table 9.2.1,Figure 9.2.3).
Th e cryptogenic species include the polyphagous pest species Myzus persicae and M. cymbalariae, which have a cosmopolitan distribution.Data concerning their host plant relationships and the distribution of other species of the genus Myzus, strongly suggest that these species originate from a continent other than Europe.Many other cosmopolitan species are not included in this list because they are thought to be of European origin, e.g.Acyrthosiphon pisum, Brevicoryne brassicae, although their origin is unclear and it remains possible that they were introduced into Europe by humans a long time ago.
Most of the alien aphid species in Europe originate from temperate regions of the world.Asia and North America have contributed the largest numbers (each 43.1%, Figure 9.2.3).Most of the Asian species originated from temperate zones (32 species), and only four species ( Cerataphis brasiliensis, Cerataphis orchidearum, Greenidea fi cicola, and Stomaphis mordvilkoi) are known to have originated from tropical Asia.Only four alien species in Europe are of African origin.Two of these species come from North Africa (Cinara laportei and C. cedri) and two from sub-Saharan regions (Aloephagus myersi and Paoliella eastopi).No alien aphid species has yet been introduced into Europe from Australasia or South America.Th e proportions of aphids of diff erent geographical origins in the alien aphid fauna of Europe have remained fairly constant over time (Figure 9.2.4) and seem to refl ect the species diversity of the donor continents.Most of the described aphid species are of temperate origin, with Aleyrodidae and Coccoidea appearing to replace aphids in the tropics and subtropics (Dixon 1998).With only 219 (Remaudière et al. 1985) and 180 (Hales 2005) species, respectively, sub-Saharan Africa and Australia have a very poor aphid fauna.By contrast, 1,416 species are found in North America (Foottit et al. 2006) and 1,007 species are found in China (Qiao and Zhang 2004).Th us, the origins of the alien species in Europe might refl ect regional species di- versity rather than preferential routes of introduction from North America and temperate Asia.

Distribution of alien species in Europe
Alien Aphididae species are not evenly distributed within Europe (Figure 9.2.5).Th e number of alien species present in a country is signifi cantly and positively correlated with the number of native species recorded in that country (r=0.6226,p<0.001).Th is may refl ect diff erences in sampling intensity and in the number of local taxonomists.Th e number of alien species also seems to be weakly positively correlated with the total area covered by each country (r=0.3361,p=0.0182).Similarly, the number of native species is strongly correlated with the area of the country (r=0.6803,p<0.001).
Alien aphid species are well distributed across Europe, with 58% present in at least fi ve European countries and 38% occurring in more than 10 countries or regions.Th e polyphagous pest species, Myzus persicae, Macrosiphum euphorbiae and Aphis gossypii are the most widely distributed alien species: they have been recorded in 43, 41 and 40 countries or regions, respectively.Only one of the 15 species occurring in more than half of the countries of Europe, Acyrthosiphon caraganae, is not considered to be a pest of crop plants.Th is species, probably originating from the Altai region, is now found in temperate regions throughout the Northern hemisphere, where it lives on woody Leguminosae, particularly Caragana and Colutea species.In most cases, it is not known whether the species expanded naturally after its establishment in a country, or whether the extension of its distribution was driven by repeated introductions from abroad.
Th irteen of the 19 species present in only two European countries have discontinuous distributions, probably resulting from independent introductions.Th us, for example Ericaphis wakibae has been found in Great Britain and the Czech Republic, Chaitophotus populifolii in Germany and Serbia and Macrosiphum ptericolens in Poland and Great Britain.A continuous but restricted area may be accounted for by recent introductions, as for Aphis illinoisensis Shimer, 1866, a pest of grapevines introduced into Greece in 2005 (Tsitsipis et al. 2005).Th is species has extended its range from Crete to continental Greece and recently (2007) to the Mediterranean part of Montenegro (Petrovic, personal communication).
Eight alien aphid species have each been found in only one European country.Four of these species are confi ned to England, two to Italy, one to Swirtzerland and one to the Ukraine.Th ese species were all introduced before 2000 and have not spread elsewhere since.Th ey may be unable to colonise a wider geographical area in Europe, they may have disappeared or they may simply have been overlooked.

Main routes and vectors for introduction into Europe
No cases of intentional introduction of aphids into Europe are known.All alien species were therefore introduced accidentally.In a very small number of cases, the pathway and vector are precisely known.For example, two Japanese aphids, Tinocallis ulmiparvifoliae and T. zelkovae were introduced into Europe in 1973 with their hosts, bonsai trees that were imported into Great Britain directly from Japan.Th e infested bonsai trees had been in Great Britain for about six months before the aphids were detected, and were growing in slatted wood buildings providing no eff ective physical barrier to insect dispersal (Prior 1971).
In most cases, it is diffi cult to identify the vector of accidental introductions; most have been inferred from the known biological requirements of the aphid species.Most Aphididae have a high level of host-plant specifi city and most alien species are therefore thought to have been introduced into Europe with their host plants.For example, the Takecallis species included in our list feed on bamboos of Asian origin.Th e Ne-  arctic aphid Prociphilus fraxinifolii has recently been detected in Budapest (Hungary) (Remaudière and Ripka 2003), but only on the North American red ash tree, Fraxinus pennsylvanica Marsh.Th is aphid has not been found on European ash planted in the same area.Two oriental species, Reticulaphis distylii and Greenidea fi cicola, live on several species of Ficus, all originating from tropical regions.Th ese Ficus species have been planted as ornamental trees in the warmest areas of the Mediterranean basin (Barbagallo et al. 2005a).Th ese two species of aphids are found on tropical fi g trees, but never on Ficus carica, the only European species of this genus.All these alien species are thought to have been introduced into Europe through trade, but the aphid species may have been introduced several years after their hosts.Impatientinum asiaticum is a species originating from Central Asia.It was introduced into Europe in 1967, whereas its host, Impatiens parvifl ora DC. was introduced into Europe much earlier, in the 19th Century, subsequently escaping from botanic gardens to establish itself as a common weed.Th e aphid was not introduced at the same time as its host plant in this case because the host plant is an annual, which was imported in the form of seeds.Th e aphid arrived more than 100 years later, probably on an aeroplane (Holman 1971, Tambs-Lyche andHeie 1973).Another example is provided by Rhopalosiphoninus latysiphon, a pest species particularly damaging to potato.Th is species was not introduced into Europe until the end of the 1 st World War, long after the introduction of its host plant, and was transported with potatoes from the USA.It was subsequently found in Italy (1921), the Netherlands (1930), Germany (1943), England (1945), Switzerland and Austria (1949) (Remaudière 1952).Finally, we cannot exclude the possibility that some species originating in areas close to Europe may have been transferred into Europe by wind, air streams or windstorms.For example, it is diffi cult to determine whether Cinara laportei and C. cedri were transferred with their host, the Atlas cedar, which was planted in Europe, or whether these species colonised Europe following their introduction via wind or air streams.

The ecosystems and habitats most frequently invaded
All aphids are phytophagous and their distribution is limited by the presence of their host plants.Aphid species with a limited spectrum of host plants of exotic origin, not present at natural sites, are restricted to artifi cial habitats, such as agricultural land, greenhouses and parks and gardens.For example, Illinoia liriodendri and Neophyllaphis podocarpi feed on exotic trees (Liriodendron tulipifera L. and Podocarpus spp., respectively).As a result, these aphids are restricted to parks, gardens and city areas in which these trees have been planted in Europe.Similarly, Cinara cedri and C. laportei which feed specifi cally on Cedrus are restricted to forest areas in which their hosts have been planted.Other species restricted to artifi cial habitats include tropical and subtropical aphids present only in indoor conditions in Europe.Th ese species were included in the list because it is clear that they have become established in Europe.For example, Cerataphis spp., particularly C. lataniae and C. orchidearum have repeatedly been found in European greenhouses (Chapin and Germain 2005).Similarly, Sitobion luteum and Pentalonia nigronervosa are considered to have been introduced into hothouses in Europe (Blackman and Eastop 2000).Another subtropical Cerataphis, C. brasiliensis, has recently been found established outdoors in the south of the France (Chapin andGermain 2005, 2004).Some aphid species have a less limited host range spectrum.Th ey can adapt to new hosts when introduced and may disperse in natural habitats.Cinara curvipes, a species recently introduced into Europe, is known to feed on various species of Abies in its native area (North America).In Europe, it is found on North American Abies species, but also on native Abies species and has recently been reported on many other conifers, including Picea, Tsuga, and Pinus (Scheurer and Binazzi 2004).C. curvipes is found in parks, gardens and forests.It could potentially colonise all European coniferous forests.Finally, polyphagous aphids, notably Myzus persicae, M. ascalonicus, M. ornatus, Macrosiphum euphorbiae and Aphis gossypi, have established themselves on many native plants in natural habitats.
Most of the alien aphids seem to have become established in the European environment and habitats.However, some species, such as Paoliella eastopi and Macrosi-phum ptericolens have been recorded only once or twice, and it remains unclear whether these species are truly established.Other species, such as Rhopalosiphum parvae Hottes & Frison (1931), a North American aphid found in Sicily in 1982 (Barbagallo and Stroyan 1982), or Tuberocephalus higansakurae hainnevilleae Remaudière & Sorin, 1993, detected in France in 1990 on trees of Prunus subhirtella Miq.var.pendula Y.Tanaka imported from Japan (Remaudière and Sorin 1993), have been observed in Europe but have since been eradicated.Such species are not included in our list.

Ecological and economic impact
Most of the alien Aphididae are recognised pests, feeding on crops, ornamental plants and forest trees in Europe.Other alien Aphididae species may have remained undetected because they feed on plants that are not commercially exploited.As for most insects, much more is known about the economic impact of aphids than about their ecological impact.Aphids cause direct (sap-feeding, deformation of their hosts) and indirect (transmission of plant diseases, deposition of honeydew on the leaves) damage.
Th e economic impact of each species depends on (i) the type and extent of the damage caused and (ii) the economic importance of the host.Of the 102 alien aphid species in Europe, 52 are recognised pests of agricultural and horticultural crops (Blackman and Eastop 2000).Th e polyphagous species Myzus persicae, Macrosiphum euphorbiae and Aphis gossypii attack a wide range of vegetable crops, both indoors and outdoors.Th ey are vectors of many viral diseases and are probably the aphids with the greatest economic impact in vegetable crops (Lampel and Gonseth 2005).
European orchards are attacked by several alien aphid species.Apple trees can be severely damaged by the North American wolly aphid Eriosoma lanigerum and the Asian species Aphis spiraecola.Th e recent introduction of Toxoptera citricidus into the Iberian Peninsula (Portugal and Spain) (Ilharco et al. 2005) poses a serious threat to Mediterranean citrus fruit production because this aphid is the principal vector of the Triteza closterovirus of Citrus.Citrus trees in Europe are also the hosts of Aphis spiraecola and Toxoptera aurantii, two polyphagous species also capable of transmitting this closterovirus, albeit with a lower effi ciency.
Th e recent introduction and rapid dispersion of Aphis illinoiensis, a grapevine aphid, poses a particular threat to viticulture in the Mediterranean area (Remaudière et al. 2003, Tsitsipis et al. 2005).Some alien aphids attack agricultural crops, often as potential virus vectors.Rhopalosiphum maidis is known as a pest of maize and other grain crops in Europe and transmits the persistent luteovirus "yellow dwarf " virus of barley.Th e grass aphid, Hysteroneura setariae Th omas, 1878, has recently been recorded in Spain (Meliá Masiá 1995).Its impact it diffi cult to predict because it usually lives on wild grass species, but it may occasionally infect cereals and can transmit several viral diseases to these crops.Macrosiphum albifrons is a widespread species in North America that has been introduced into Europe (Stroyan 1981) where the damage it causes to lupins (Ferguson 1994) has stimulated recent research (Blackman and Eastop 2000).Finally, Acyrthosiphon kondoi, which currently has a restricted distribution in Europe, is known to be a serious pest of lucerne (Blackman and Eastop 2000).
Exotic Aphididae are not considered to be serious pests of forest species in Europe (EUROFOR 1994) by contrast to the major damage caused to agricultural and horticultural crops.However, some species may cause economic losses.For example, the North African species Cinara cedri and C. laportei have been reported to damage plantations of Cedrus in southern France (Emonnot et al. 1967, Fabre 1976).
Finally, in addition to their measurable economic impact, some alien aphids may have an aesthetic impact.Th e production of abundant honeydew and the distortions induced by feeding may signifi cantly modify the appearance of the foliage of ornamental plants in parks and private gardens.Appendiseta robiniae has such an aesthetic impact on Robinia pseudacacia L., as does Prociphilus fraxinifolii on the red ash tree Fraxinus pennsylvanica and Illinoia liriodendri on Liriodendron tulipifera.

Conclusion
Th ere are several possible reasons for the overrepresentation of Aphididae in the alien insect fauna of Europe.First, aphids are phytophagous insects and many are pests of economically important host plants (Blackman and Eastop 2000).For this reason, many studies are carried out on the distribution, taxonomy and biology of this family.New alien species of Aphididae are therefore more likely to be detected than new members of other taxonomic groups, and this eff ect is enhanced by standard phytosanitary procedures.Second, aphids have the ability to reproduce both parthenogenetically and sexually.Several species can reproduce exclusively by parthenogenesis, and all species can potentially maintain parthenogenetic populations throughout the year in areas of mild climate.Consequently, very few introduction events, and theoretically even the introduction of a single parthenogenetic female, may lead to the development of a population and the establishment of an alien species.Th ird, although aphids, as a group, are cosmopolitan, they are most strongly represented in temperate regions.Consequently, most of the World's aphids live in climatic conditions similar to those of Europe and are therefore preadapted to establishment where suitable hostplants are present.Moreover, global warming is also likely to promote the survival of alien tropical and subtropical species, at least locally (e.g.along the Mediterranean coast).Finally, aphids are small insects easily transported around the globe with plant materials.

Figure 9
Figure 9.2.1.Taxonomic overview of the aphid species alien to Europe compared to the native European fauna and the world fauna.Subfamilies are presented in a decreasing order based on the number of alien species.Species alien to Europe include cryptogenic species.Data about native European aphids from Fauna europaea (Nieto Nafria et al. 2007); world data from Remaudière and Remaudière (1997).Th e number over each bar indicates the number of species observed per subfamily.

Figure 9
Figure 9.2.2.Changes over time in the mean number of fi rst sightings per year of aphid species alien to Europe from 1492 to 2007.Th e number to the right of the bar indicates the absolute number of species reported for the fi rst time during the corresponding time period.

Figure 9
Figure 9.2.3.Geographic origin of the alien species of Aphididae established in Europe.

Figure 9
Figure 9.2.4.Cumulative numbers of alien aphid species established in Europe, by year and by geographic origin

Table 9
.1.1.List and main characteristics of Aphididae species alien to Europe.Status: A: Alien to Europe; C: cryptogenic species.Country codes abbreviations refer to ISO 3166 (see appendix I).Habitat abbreviations refer to EUNIS (see appendix II).Only selected references are given.Last update February 2010.