Developing semiochemical repellents for protecting Picea from Dendroctonus rufipennis (Coleoptera: Curculionidae) in Alaska and Utah, USA

Abstract

Spruce beetle, Dendroctonus rufipennis(Kirby) (Coleoptera: Curculionidae), is the most destructive pest of mature spruce (Picea) in western North America. Recent outbreaks in Alaska and other western US states highlight the need for tools to protect Piceafrom D. rufipennis. The primary antiaggregation pheromone of D. rufipennis(3-methylcyclohex-2-en-1-one, MCH) and various combinations of potential repellents (1-octen-3-ol, exo-brevicomin, endo-brevicomin, ipsdienol, ipsenol, limonene, and verbenone) were tested for their ability to disrupt the response of D. rufipennisto attractant-baited multiple-funnel traps. Two assays were conducted on the Kenai Peninsula, Alaska, in June and July 2021. All treatments significantly reduced the mean number of D. rufipenniscaught compared to the baited control. No other significant differences were observed among treatments. Informed by these and other data, tree protection studies were established in Lutz spruce, Picea × lutzii, on the Kenai Peninsula in 2022 and in Engelmann spruce, Pi. engelmannii, in the Uinta Mountains, Utah, in 2021. All experimental trees were baited with frontalin. Repellent treatments included MCH (SPLAT MCH, ISCA Inc., Riverside, CA, USA) and at least 1 additional repellent combination. In Alaska, all treatments significantly reduced colonization (strip attacks + mass attacks) and mortality of individually treated Pi. × lutziiand all Piceawithin 11.3-m radius of each treated Pi. × lutziicompared to the control. In Utah, all treatments except for SPLAT MCH + octenol significantly reduced colonization compared to the control. Only SPLAT MCH + Acerkairomone blend (AKB) and SPLAT MCH + octenol reduced Pi. engelmanniimortality compared to the control. SPLAT MCH + AKB and SPLAT MCH + acetophenone and green leaf volatiles (PLUS) were the most effective across both studies. The implications of these and other results to the development of an effective semiochemical repellent for D. rufipennis are discussed.

Citation

Audley, Jackson P; Fettig, Christopher J; Moan, Jason E; Moan, Jessie; Swenson, Steve; Munson, A Steven; Mortenson, Leif A; Blackford, Darren C; Graham, Elizabeth E; Mafra-Neto, Agenor. 2024. Developing semiochemical repellents for protecting Picea from Dendroctonus rufipennis (Coleoptera: Curculionidae) in Alaska and Utah, USA . Journal of Economic Entomology. 115(1): 2772. https://doi.org/10.1093/jee/toae070.