HONEY eDNA IS AN EFFECTIVE TOOL FOR DETECTING AND MONITORING INFESTATIONS OF THE PINE TORTOISE SCALE (TOUMEYELLA PARVICORNIS, COCKERELL) PEST

Environmental DNA (eDNA) is considered a non-invasive methodology that can facilitate the detection and monitoring of invasive species that would be difficult to identify with other approaches. Honey contains eDNA derived from all organisms encountered by honey bees during foraging in the ecological landscape. This matrix represents a valuable source of information on plant-sucking insects that produce honeydew, which is used by honey bees as a sweet feed source. In this study, we used honey eDNA to develop an assay to detect the pine tortoise scale, Toumeyella parvicornis (Cockerell), a harmful invasive pest alien to Europe that in the recent years has caused a serious threat to many stone pines (Pinus pinea). A few pine tortoise scale specimens were collected from infested trees and two species-specific primer pairs targeting COI and 16S mitochondrial genes were designed to confirm species identification through PCR and sequencing. These specific primer pairs were then used in PCR assays targeting T. parvicornis DNA traces recovered from honey produced in areas with known and yet undeclared pine tortoise scale infestations. A total of 864 honey samples produced over 8 years (2018-2025) across central-southern Italy were analysed. Overall, the Lazio and Campania regions carried the most positive samples for T. parvicornis (>50%), followed by Toscana, Abruzzo, Marche and Puglia regions. Interestingly, this pest was also identified in unexpected areas where it had never been detected before. The results showed an increased number of positive samples in the more recent years (2024-2025), in line with the rise in outbreaks across Italy. Given the current difficulty in detecting early-stage T. parvicornis infestations, this approach could be implemented into pest early detection and monitoring systems. These results demonstrate the usefulness of honey eDNA in the surveillance of environmental invasive pests, representing a promising tool for large-scale ecosystem monitoring.