Movement of Xylosandrus germanus (Coleoptera: Curculionidae) in Ornamental Nurseries and Surrounding Habitats

Abstract

Some exotic ambrosia beetles are damaging pests in ornamental nurseries. Xylosandrus germanus (Blandford) is the most problematic ambrosia beetle in Ohio nurseries. Movement of X. germanus in nurseries has not been characterized, and knowledge is lacking on whether infestations originate from within nurseries or surrounding habitats. Flight activity of X. germanus was monitored in nurseries and adjacent wooded areas to determine the source of beetles infesting nurseries, and characterize their movement within nurseries. Ethanol-baited bottle traps were positioned within wooded areas adjacent to commercial nurseries and within nurseries at various distances from the nursery woodlot interface. Flight activity of overwintered X. germanus occurred in wooded areas adjacent to nurseries before occurrence within nurseries. There was a direct relationship between degree-days and the distance from woodlots when X. germanus were first found in traps in spring, with earlier captures closest to wooded areas and latest ones furthest away into the nursery. X. germanus appeared to move into nurseries from adjacent wooded areas, with numbers trapped within nurseries decreasing with distance away from wooded areas. Trees in the interior of nurseries would appear to be subjected to less attack pressure than trees near the nursery border. Intercepting beetles as they move into nurseries might be an effective strategy to reduce attack pressure on valuable trees.