Th e times they are a-changin’:S. Grozeva driving forces & N. of Simov recent additions(Eds) 2008 to the Heteroptera fauna of Austria 309 ADVANCES IN HETEROPTERA RESEARCH Festschrift in Honour of 80th Anniversary of Michail Josifov, pp. 309-326. © Pensoft Publishers Sofi a–Moscow Th e times they are a-changin’: driving forces of recent additions to the Heteroptera fauna of Austria * W. Rabitsch Federal Environment Agency, Spittelauer Lände 5, A-1090 Wien, Austria. E-mail: [email protected] Department of Evolutionary Biology, University of Vienna, Althanstraße 14, A-1090 Wien, Austria. E-mail: [email protected] ABSTRACT During the past approximate 25 years 84 Heteroptera species were published for the fi rst time for Austria. Th ese species account for 9.4 % of the 896 Heteroptera species currently known to occur in Austria and means that species were added at a rate of more than 3 per year, including previously overlooked species. Two thirds of the species (68 %) were overlooked for taxonomic reasons or because of their cryptic appearance or biol- ogy; the remaining species (32 %) are considered new arrivals. Excluding single records, 18 species (21 %) are considered established new arrivals. Th is is a rate of 0.72 species establishing per year. Most of these species are generally expanding their distribution and increasing in abundance in Austria and elsewhere in Europe and most species reached Austria probably due to current favourable climatic conditions (14 species), followed by species introduced with ornamental plants or transport (4 species). Th e dominance of arboricolous, phytophagous species with a high degree of host plant specialization cor- roborates previous fi ndings. Th e native region of 14 of these 18 species is the Mediter- ranean, resulting in a current “Mediterranization” of the Heteroptera fauna of Austria. Such a movement probably has happened before (1932–1940), but most of the species failed to establish in Central Europe. Most species arrive in the north-east of Austria, which may be a preferred invasion gateway for southeast-mediterranean species, due to the barrier eff ect of the Alps. Beside climatic factors, habitat change – particularly * Th is paper is dedicated to Michail Josifov at his 80th birthday and his stimulating biogeographical and taxonomic contributions to the Heteroptera of Europe. 310 W. Rabitsch availability of ornamental plants in urban settings – is considered an important driving force of recent additions to the Heteroptera inventory of Austria. Further monitoring of Heteroptera occurrence in Austria is needed to detect and verify this pattern. Keywords: Austria, climatic change, non-native species, Heteroptera INTRODUCTION Th e accelerating pace of human impact on the environment in the last decades has caused a multitude of alterations, such as changes of element cycling and of climate as well as a dramatic decline of biodiversity (Sala et al. 2000; Chapin et al. 2001). However, at the local scale, biodiversity in terms of species numbers can rise due to man-made in- troductions of species beyond natural boundaries. Th ese non-native (alien) species may harm native species or have economic cost; non-natives are considered second only to land use change as driving force for loss of global biodiversity (Vitousek et al. 1997; Wilcove et al. 1998) and are responsible for an economic loss equal to about 5 % of the world GNP (Pimentel 2002). Several driving forces are responsible for changes in the fauna of a given area. Beside anthropogenic forces (intentional release, unintentional introduction with plant mate- rial or as stowaways with goods or stored products), there are natural biotic and abiotic forces (the edges of species ranges are not stable and natural progression and regression of ranges do occur) and – of course – an interaction of both (e.g. Dukes & Mooney 1999; Gaston 2003). It is, therefore, diffi cult to uncouple the driving forces of range changes, but climatic change is clearly one of the most important (e.g. Parmesan 1996, 2006; Cannon 1998; Parmesan et al. 1999; Burton 2001; McCarty 2001; Hill et al. 2002; Walther et al. 2002, 2005; Root et al. 2003). In this paper, new additions to the Heteroptera fauna of Austria over the past ap- proximate 25 years are summarized and discussed in the light of their possible driving forces of change. A descriptive, not statistically based, prediction for a future scenario is made. METHODS Th e available literature on the Heteroptera of Austria (see Rabitsch 2006) was checked for new species records since and including the seminal paper of Melber et al. (1991), considering records back to 1982. Th e present study therefore deals with new additions to the species inventory for approximately the last 25 years. While collating data for a critical check-list of Austrian species (Rabitsch 2004a, 2005b) and a red list of endangered species of Lower Austria (Rabitsch 2007), voucher specimens were verifi ed in several museum and private collections (Burgenländisches Landesmuseum, Eisenstadt; Kärntner Landesmuseum, Klagenfurt; Muséum d`Histoire Naturelle, Geneva; Naturhistorisches Museum, Wien; Th e times they are a-changin’: driving forces of recent additions to the Heteroptera fauna of Austria 311 Niederösterreichisches Landesmuseum, St. Pölten; Oberösterreichisches Landesmuseum / Biologiezentrum, Linz; Zoologisches Museum, Universität Hamburg; Zoologische Staatssa- mmlung, München). Altogether, approximately 40,000 data entries were analysed. Species were assigned to diff erent categories as to the reason for their addition to the national list (new arrival or overlooked) as well as the likely driving force for arrival where appropriate: (i) species overlooked due to taxonomic changes, (ii) species over- looked due to cryptic biology (including rare species), (iii) new arrivals, probably due to climatic change, (iv) new arrivals, probably due to unintentional introduction (either with ornamental plant trade or with transport of goods). Further, the status of the spe- cies in Austria was evaluated from available data, and biological features of the species were compiled from the literature. RESULTS During the past approximate 25 years 84 Heteroptera species were published for the fi rst time (or confi rmed as being present) for Austria (Tab. 1). Th is is 9.4 % of the 896 Heteroptera species currently known to occur in Austria (Rabitsch 2004a, 2005b; Rabitsch et al. 2007; Rabitsch & Heiss 2008) and means that species were added at a rate of more than 3 per year, including those previously overlooked. Th irty-seven species were recorded based on historic material (collected before 1980) and 12 of these were not found again. Fifty-seven species are considered to have been overlooked and 27 species are considered as new arrivals. Within the overlooked species, 16 species were overlooked probably due to taxonomic changes, 25 species were overlooked probably due to their cryptic habit or biology and 16 species were overlooked for both reasons. Of the 27 new arrivals, the establishment of 9 species is doubtful or unknown because they are known only from a single record. Th is leads to 18 established new arrivals; a rate of 0.72 species added per year. Th e following comparisons are made between the complete data set (n=84) and the new arrival data set excluding doubtful records (n=18). Climatic conditions are considered to be the main driving force (14 species) for the 18 new arrivals, followed by introduction with ornamental plants or transport (4 species). Almost all of these species (15 of 18) are considered to be expanding their range and currently are increasing in abundance within in Austria and beyond. Th e native region of 14 of these 18 species is the Mediterranean (7 Ponto-Medi- terranean, 4 Holo-Mediterranean, 2 Atlanto-Mediterranean, 1 North-Mediterranean), two species are of Eastern Palaearctic origin, one species is of Eurosiberian origin and one species (Leptoglossus occidentalis Heidemann, 1910) is of Nearctic origin. Most spe- cies of the complete data set belong to Miridae (30 species), followed by Lygaeidae (15 species) and Anthocoridae (8 spp.). Th e same families dominate within the newly arrived species: Miridae (5 species), Anthocoridae and Lygaeidae (3 species each). Most of the species occur in the Pannonic region of Austria (31 % in Lower Austria, 24 % in Burgenland, 15 % in Vienna). Considering stratum preference, arboricolous spe- 312 W. Rabitsch cies, living on trees and shrubs, dominate (45 %), followed by herbicolous and epigaeic species (30 % and 21 %, respectively) in the new arrival species and with similar propor- tions in the overlooked species. As expected, the proportion of epigaeic species with a more concealed way of life is rather high within the overlooked-cryptic species (46 %). Th e average body size of the Heteroptera species in Table 1 is 5.3 mm. Almost all of the species develop a single generation per year. Whereas no preponderance of a particular mode of hibernation was found in the complete data set, hibernation as adults clearly prevails among the new arrival species (70 % vs 20 % as eggs and 10 % as larvae). Phytophagous species dominate both data sets (46–52 %), followed by zoophagous species (25–27 %) and zoophytophagous species (18–21 %). Th ere is a high degree of food plant or prey specialization in both data sets. Monophagous, oligophagous and polyphagous species (30–40 %) were almost equal. Almost all new arrivals are macropterous and ca- pable of fl ying. Notable exceptions are the regularly apterous (rarely winged) Metapterus caspicus (Reduviidae) and the sexually dimorphic Mimocoris rugicollis (Miridae), the latter with winged males only. Habitat selection of new arrivals revealed a preference in decreasing order of open-land, forest-land and synanthropic habitats with not a single aquatic or semiaquatic species. DISCUSSION In Europe, during the last decades, an increasing number of insect species have shifted their range northwards from the Mediterranean (Reemer et al. 2003; Hickling et al.