Ornamental nurseries adjacent to hardwood-dominated woodlots pose more risk from exotic ambrosia beetles (Xylosandrus spp.) (Coleoptera: Curculionidae: Scolytinae) than pine-dominated woodlots

Exotic granulate ambrosia beetle, Xylosandrus crassiusculus (Motschulsky), black stem borer, Xylosandrus germanus (Blandford), and black twig borer, Xylosandrus compactus (Eichhoff) are serious pests of woody ornamental trees in nurseries. Woodlots often surround ornamental nurseries, where the ambrosia beetles fly into nurseries and attack young trees. The woodlots are either dominated by hardwood trees, such as Oaks (Oak spp.), maples (Acer spp.), or pine trees, mainly loblolly pine (Pinus taeda L.). It is unclear if the woodlot type would influence the abundance of ambrosia beetle pests flying outside the woodlot. Thus, this study aimed to determine whether the hardwood or pine-dominated stand affects the relative abundance of ambrosia beetle pests outside the woodlot. In 2023 and 2024, experiments were conducted by deploying 3 ethanol-lured plastic bottle traps in 4 hardwood and 4 pine-dominated woodlots in mid-Georgia (USA). The overall captures of X. crassiusculus and X. germanus were significantly greater in the hardwood than in the pine-dominated woodlots in both years. The numbers of X. crassiusculus and X. germanus collected in traps were not consistently significantly different between the hardwood and pine-dominated woodlots for most sampling dates. The captures of X. compactus were not influenced by woodlot type. This suggests that although ambrosia beetle pests were collected from both hardwood and pine-dominated woodlots in both years, the risk of infestation in nurseries is greater from the adjacent hardwood than pine-dominated woodlots.