Invasive species-powerful competitors to the native species.
In Romania, as well as in Europe, there are many vegetal and animal species that have acclimated and rapidly spread aggressively occupying even larger areas, and their activity often influences negatively the ecosystems in which they grow. The number of invasive species registered in Romania is very high; it comprises plants such as Galinsoga parviflora, mammals such as Canis aureus, birds such as Streptopelia decaocto, fishes such as Ictalurus nebulosus [Ameiurus nebulosus], gastropods such as Rapana tomasina, aranea such as Latrodectus spp. The largest number of invasive species is represented by the insects, some of them being veterans of the invasion, such as Leptinotarsa decemlineata, Hyphantria cunea, Phylloxera vastatrix [Viteus vitifoliae], Quadraspidiotus perniciosus [Diaspidiotus perniciosus] and other new guests such as Phyllonorycter robiniella and Parectopa robiniella, Cameraria ohridella, Diabrotica virgifera virgifera, Anoplophora chinensis and Anoplophora malasiaca, Linepithema humile, Lasius neglectus. All these species have a powerful negative impact on the cultivated plants or on the spontaneous flora and they do not present specific entomophagy, which makes them difficult to control with biological methods.