Ambrosia Beetle Occurrence and Phenology of Xylosandrus spp. (Coleoptera: Curculionidae: Scolytinae) in Ornamental Nurseries, Tree Fruit, and Pecan Orchards in Georgia

Ambrosia beetles (Coleoptera: Curculionidae: Scolytinae, Platypodinae) in the genus Xylosandrus are problematic in ornamental nurseries and are emerging as serious pests in orchard crops. An updated survey of ambrosia beetles focusing on these damaging species, and their corresponding phenology was conducted in Georgia to aid in refining management practices for these beetles. Ambrosia beetles were monitored across nine sites in 2019 and seven sites 2020 at ornamental nurseries, tree fruit, and pecan orchards in Georgia. At each site, six ethanol-baited bottle traps were deployed; with three traps along the edge of a wood-line and three traps placed 30 m from the edge of the nurseries and orchards. Traps were deployed from mid-January through July or August depending on site and year. All captured ambrosia beetles were counted and identified. Captures of X. crassiusculus, X. germanus, and X. compactus, were analyzed further to investigate spatial distribution and seasonal flight activity. At high population sites, more beetles were captured along adjacent wood lines than in the orchard or nursery interior. At most sites, flight activity began in February and March continued until the termination of the study in July or August. At most sites, sustained flight activities with multiple peaks were observed in March, April, and May, corresponding to average weekly temperatures reaching ≥15.5°C. These results have important implications on temporally and spatially precise management for these beetles across three important agricultural production systems in the southeastern US.