Alien and Invasive Insects in Croatian Forest Ecosystems and Estimate of their Damage

Cilj istraživanja bio je utvrditi strane i invazivne vrste štetnih kukaca koje su se udomaćile u šumskim ekosustavima Hrvatske, procijeniti njihovu štetnost i prognozirati njihovo daljnje širenje. Potvrđena je prisutnost 7 vrsta kukaca iz redova Hemiptera, Diptera, Lepidoptera i Hymenoptera koji se mogu smatrati stranim, odnosno invazivnim vrstama kukaca. To su Parectopa robiniella, Phyllonorycter robiniella, Phyllonorycter issiki, Obolodiplosis robiniae, Leptoglossus occidentalis, Metcalfa pruinosa i Dryocosmus kuriphilus. Za svaku nađenu vrstu daje se prognoza njezinog širenja i šteta u sljedećim godinama. Ovo istraživanje pokazalo je da su se strane vrste udomaćile u šumskim ekosustavima Hrvatske, a neke od njih su potencijalni ozbiljni šumski štetnici.Alien species are intentionaly or unintetionaly introduced species into new area. When an alien species succefully invades and impacts a new ecosystem it becomes an invasive species. Until today, 109 invasive insects on woody plants (57 from North America, 52 form Asia) have been introduced and established in forest ecosystems in Europe (MATTSON et al. 2007). Introduction and dispersal of new species is increasing from year to year due to globalization of trade and ever increasing tourist traffic between continents. The aim of this research was to identify most important alien and invasive insect species in Croatian forests and give an estimate od their damage and prognosis of their future spread. The research has lasted for 5 years (2006 to 2010) and potential host plants in continental, submediterranean and mediterranean parts of Croatia were researched. For each invasive species found a prognosis for their future spread and damages is given according to their biology, ecology, researches on natural enemies and data from the literature. Seven (7) insects species from the orders Lepidoptera, Hymenoptera, Diptera and Hemiptera were found and they can be cosidered as alien or invasive species in Croatian forest ecosystems (Table 1). For each insect species a host plant, locality where the insect was found and prognosis of damage on the scale from 1 to 4 (1-no influence on host plant, 4-serious forest pest) is given. Parectopa robiniella, Phyllonorycter robiniella, Phyllonorycter issiki, Obolodiplosis robiniae, Leptoglossus occidentalis, Metcalfa pruinosa, Dryocosmus kuriphilusare alien or invasive insects established in Croatian forests. Introduction and spread of these species and their intensity of occurence has been very similar to the same pattern of spread and occurence in other Euro-paean countries. Several other invasive species on woody ornamental plants in urban areas have also been recorded in Croatia: Phyllonorycter leucographella, Dasineura gleditchiae,Argyresthia thuiella, Cameraria ohridella, Anoplophora chinensis. Knowledge on insect origin, biology, ecology, pathways of introduction and spreading are very important for providing pest risk analysis and making relevant prognosis of dangers that a new pest is posing for forest ecosystems