Five new invasive forest insect species in the north-eastern part of Romania.
All countries, including Romania, are increasingly affected by biological invasions. As a result, the need to study this phenomenon has become increasingly apparent. The aim of the present paper is to report the presence of five new forest insect species recently found in the northeastern part of Romania and data on their distribution in the region. The detection of the insect presence was done using identification sheets based on their morphological aspect and the characteristics of the attack, following a protocol that would make investigating work more efficient. Of the alien species found, five are new to the area of Moldova and are discussed in the present paper. They are: Dasineura gleditchiae (Osten Sacken, 1866), Appendiseta robiniae (Gillette, 1907), Prociphilus fraxinifolii (Riley, 1879), Corythucha arcuata (Say, 1832) and Nematus (Pteronidea) tibialis Newman, 1837. The first three are also new species for Romania's fauna. For each species, data are presented concerning the systematic classification and the host species, where and when it was found, the type of crop and the age of the infested trees, the frequency and severity of the attack, the region from which it originated, where it was reported for the first time in Europe and in the neighboring countries of Romania, and to what extent it is a potentially harmful pest. All species presented in the work come from North America and four of them have been found on host species from their native area (black locust, honey locust and green ash), while the fifth is mainly found on native species of the genus Quercus. Except for C. arcuata, all of them have been present in Romania, including the studied region, for at least a decade or even longer, but have gone unnoticed in the absence of research like those presented in this paper. Currently they are present almost everywhere where their host species are grown. Apart from N. tibialis, the insect species reported have the potential to become important pests of their hosts. As a result, it is necessary to study their biology and ecology in the ecosystems in which they entered in Romania.