INVADING THE MEDITERRANEAN: STUDY OF SOLANUM ELAEAGNIFOLIUM, A SUCCESSFUL INVASIVE PLANT FROM C. AMERICA Thomas Tscheulin, Theodora Petanidou, Christina Zografou, Kiriaki Pantelis University of the Aegean, Department of Geography Abstract The number of alien (non-native) organisms in natural habitats is growing. They are introductions from other habitats, which often share similar climatic conditions. Aliens that adversely affect the habitat they invade ecologically, environmentally or economically are called invasives. Typical pathways of invasion are the pet trade, horticultural trade, shipping industry (ballast water), agricultural produce and biological control. We focus our research on the distribution and impact of the Central American invasive plant Solanum elaeagnifolium on the native flora and fauna of Greece. In particular we map the plant’s current distribution in the country and examine its’ impact on the pollination of the native species Glaucium flavum and the infestation of the potato crop with the Colorado potato beetle (CPB) on Lesvos Island. We analysed questionnaires sent to state-employed and private agronomists in all 52 prefectures of Greece. According to our survey, S. elaeagnifolium is present in 24 of the 33 prefectures from where we received filled out questionnaires. We complemented our results with historical data, which confirm the plant’s presence in 15 prefectures also highlighted by our survey and add an additional seven invaded prefectures. Our research shows that flowers of our native indicator plant, G. flavum, receive significantly fewer visits in populations that are invaded by S. elaeagnifolium, which may impact seed set. This has important conservation implications as pebble and shingle beaches and their perennial vegetation, to which G. flavum belongs have been designated as special areas of conservation in Annex I of the EU Habitat Directive 92/43/EEC. Furthermore, we show first evidence that S. elaeagnifolium may act as a stepping stone for CPB facilitating the infestation of the summer potato crop, which would have grave economical impacts. Key words: invasive, competition, pollination, Colorado potato beetle, Glaucium flavum 1 Introduction 1.1 Biological invasion Biological invasion is a main driver for global biodiversity loss and is increasing through globalization, trade and tourism. Typical pathways of invasion are the pet trade, horticultural trade, shipping industry (ballast water), agricultural produce and biological control. Aliens that spread and adversely affect the habitat they invade ecologically, environmentally or economically are called invasives. Biological invasions cost the U.S. economy alone over $100 billion per year in losses, damages, and control (Pimentel et al. 2000). Biological and ecological traits of an introduced species are important factors and decide whether the alien species establishes and spreads in the new habitat or not. In plants, traits that can facilitate establishment are e.g. fast growth, deep root system, vegetative as well as sexual reproduction, tolerance of a wide range of environmental conditions, prolonged flowering, early sexual maturity, high reproductive output and dispersal. Kolar and Lodge (2001) showed that from a list of invasive and non-invasive species 86% of the invasive species could be identified on the basis of their traits alone. Most alien plants have left behind their enemies (herbivores and pathogens), which often explains their increased competitive ability (Maron and Vila 2001). In this study we generate a new distribution map of the invasive Solanum elaeagnifolium (Cav.) based on questionnaires sent to agronomists in all prefectures of Greece and historical data. 1.2 Impact on native plants Invasive plants threaten biodiversity and ecosystem functioning (Pimentel et al. 2001, Traveset and Richardson 2006, Bjerknes et al. 2007), because they may displace native plants and crop species due to