Phoretic mite communities associated with Ips typographus (Linnaeus, 1758) and Ips duplicatus (Sahlber, 1836) (Coleoptera: Scolytinae) in a Norway spruce stand

European spruce bark beetle Ips typographus (Linnaeus, 1758) is considered the most destructive and aggressive pest of Norway spruce in Europe. Recently, Ips duplicatus (Sahlberg, 1836), another species of bark beetle, primarily affecting the genus Picea , has expanded its range westwards in Europe. In spruce stands, bark beetle populations are closely associated with various organisms such as fungi, nematodes, and mites. Mites, due to the lack of specialized dispersal organs for covering long distances, use bark beetles through a phenomenon known as phoresy. While phoretic mites and their relationship with Ips typographus have been extensively studied in Europe, very few studies have focused on the populations of phoretic mites associated with Ips duplicatus . The aim of this study is to analyze and document the communities of phoretic mites and their complex relationship with the two species of bark beetles in the same location. The research was conducted in a stand located at the lower limit of spruce, where the two pest species have developed outbreaks together. Over 50,000 beetles were collected using wing-type pheromone traps, of which 4,348 were analyzed for the determination of phoretic mites (2,413 Ips typographus ; 1,935 Ips duplicatus ). In total, nine species of phoretic mites were identified, of which only six were found on Ips duplicatus . Among the nine species, Dendrolaelaps disetus (Hirschmann, 1960), Elattoma sp. , and Paraleius leontonychus (Berlese, 1910) are reported for the first time in Romania. The results highlighted that although Ips typographus beetles were significantly more phorezed than Ips duplicatus beetles throughout the entire flight period, the peaks of phoretic rates were similar. ONE-WAY PERMANOVA test revealed significant differences between the two phoretic mite communities, differences also highlighted by diversity indices. These differences are most likely due to the presence of certain mite species only on Ips typographus beetles, as well as differences between the populations of common species. Regarding the location of phoretic mites on the insects' bodies, this varied depending on the mite species and the host.