First Record of the Ambrosia Beetle Xylosandrus compactus (Coleoptera, Curculionidae) in Croatia

(1) Background: The invasive ambrosia beetle Xylosandrus compactus (Coleoptera, Curculionidae, Scolytinae) poses an increasing risk of being introduced into new environments, mostly unintentionally, via wood products, live plants, and wood packaging materials. It is already spreading across Europe and causing growing concern due to its destructive behavior and by infesting a wide range of woody plants. The aim of this research is to identify X. compactus in Croatia and compile a list of recorded host plants. (2) Methods: Fieldwork was conducted through the assessment of beetle presence and infestation levels on host plants showing visible symptoms of attack, as well as through sampling of the beetles. Adult specimens of bark beetles were examined under a microscope, and molecular analysis was done. DNA was extracted from three randomly chosen individuals. The sequences were compared using the BLAST tool in the NCBI GenBank database. (3) Results and Conclusions: X. compactus was confirmed as a new record in Croatia, infesting laurel (Laurus nobilis), holm oak (Quercus ilex), laurestine (Viburnum tinus), olive (Olea sp.), myrtle (Myrtus communis), strawberry tree (Arbutus unedo), and pittosporum (Pittosporum tobira).