Flight phenology and influence of region and habitat on the abundance of Xylosandrus germanus and Anisandrus maiche (Coleoptera: Curculionidae: Scolytinae) in New York

Authors: Milbrath, Lindsey; Biazzo, Jeromy; VAN ZOEREN, JANET - Cornell University

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/14/2025
Publication Date: 1/28/2025
Citation: Milbrath, L.R., Biazzo, J., Van Zoeren, J. 2025. Flight phenology and influence of region and habitat on the abundance of Xylosandrus germanus and Anisandrus maiche (Coleoptera: Curculionidae: Scolytinae) in New York. Environmental Entomology. 54(2):386-393. https://doi.org/10.1093/ee/nvaf010.
DOI: https://doi.org/10.1093/ee/nvaf010

Interpretive Summary: The black stem borer (Xylosandrus germanus) is an introduced ambrosia beetle that is a pest of ornamental and orchard trees. It was first reported in New York apple orchards in 2013. During trapping in 2021, we identified another introduced species of ambrosia beetle, Anisandrus maiche, that looks very similar to the black stem borer and may have been misidentified in previous years. To better understand where these two species occur and when they can potentially attack trees, we trapped at four apple orchards in upstate New York over two years including in neighboring woods. The black stem borer was trapped, i.e., was flying to attack other trees, from mid-April into early October. It was abundant in orchards near Lake Ontario but less so further south in the Finger Lakes region. In contrast, A. maiche was abundant in the Finger Lakes but rare near Lake Ontario. It was trapped from late-May to mid-September. Both species can therefore potentially infest stressed apple trees throughout the growing season. Beetle captures of both species were generally highest in the wood interior and declined toward the orchard edge; a current practice of trapping at wood edges for monitoring beetle flights should continue.

Technical Abstract: The wood-boring and symbiotic fungus-culturing Xylosandrus germanus (Blandford) was first reported in New York apple orchards in 2013; trapping surveys have been annually conducted to assist growers in timely applications of preventative control measures. In 2021, we identified in traps in west central New York a similar-looking introduced species, Anisandrus maiche (Kurentzov). It was first recorded in 2005 in Pennsylvania but its history in New York apples was unclear due to potential misidentification. We collected and identified ambrosia beetles using ethanol-baited bottle traps in 2022 and 2023 in New York at two commercial apple orchards near Lake Ontario and two cider apple orchards in the lower Finger Lakes district. Traps were placed in a wood interior, the wood edge, and the orchard edge at each site. Xylosandrus germanus was trapped from mid-April into early October. It was abundant in the Lake Ontario region, but trap counts were lower in the Finger Lakes. In contrast, counts of A. maiche were very high in the Finger Lakes but extremely low near Lake Ontario. It was trapped from late-May to mid-September. Other bark and ambrosia beetle species were mostly uncommon. Captures of X. germanus and A. maiche were generally highest in the wood interior and declined toward the orchard edge, but each species was usually present in traps across habitats at the same time. The practice of trapping at wood edges should continue. Both species potentially can infest stressed apple trees throughout the growing season.