What Really Lurks in the Dark? Revisiting the Occurrence of Tomicus destruens (Coleoptera, Curculionidae, Scolytinae) in Greece

Tomicus destruens (Wollaston), the Mediterranean pine shoot beetle, has long been confused with Tomicus piniperda (Linnaeus) in Greece, as well as in many other Mediterranean countries. To clarify its presence and population structure, we analyzed COI sequences of specimens from 21 Greek sites (including islands) and compared them with samples from central (Italy) and western (Spain) Mediterranean populations. Greek populations were dominated by a single haplotype (Td06), whereas Samothraki Island harbored several private haplotypes, indicating long localized lineage persistence. In contrast, Italian and Spanish populations showed high haplotype diversity with many region-specific lineages, consistent with long-term refugial stability in the central-western Mediterranean. Physiological measurements further differentiate the two species: the mean supercooling point (SCP) of Greek T. destruens (–12.3 °C) was substantially higher than reported for T. piniperda (≈–18 °C), demonstrating lower cold tolerance. This supports its restriction to mild Mediterranean climates. Overall, our results confirm the dominant occurrence of T. destruens with no recovery of T. piniperda individuals in Greece and highlight the combined value of genetic and physiological markers for resolving species boundaries and understanding Mediterranean bark beetle biogeography.