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Student Regular 10-Minute Presentation

Plant-Insect Ecosystems

Student

Student Regular 10-min: P-IE, General 1

Susceptibility of evolutionarily native and naive true fir species to Adelges piceae

Sunday, November 9, 2025
10:00 AM - 10:12 AM Pacific
Location: Oregon Convention Center, E146, OCC
Oral Presentation
Adelges piceae (Ratzeburg) (Hemiptera: Adelgidae) is an invasive insect that was introduced to eastern North America in the early 1900s from Europe. In the 1930s it was detected in the Pacific Northwest (PNW) infesting true fir (Abies) species in the Willamette Valley. It remained undetected in the Cascade Mountain Range until 1954 where it was found causing mortality in the Gifford Pinchot National Forest (GPNF) in Washington. Despite long-term A. piceae infestations, some true fir stands continued to persist, suggesting potential resistance to A. piceae. In this project, we passively (using a novel method) and manually inoculated grand and subalpine fir seedlings, which were grown from parent tree seeds originating from the GPNF that have withstood long-term A. piceae infestations, with A. piceae to measure their susceptibility. We also compared the susceptibility of these native PNW fir species to three fir species native to eastern North America (balsam, Canaan, and Fraser), and two fir species (Nordmann and Turkish) native to Europe, which are the evolutionary native host of A. piceae. Results demonstrate that the passive method was effective in inoculating seedlings with A. piceae. There was also a positive relationship between A. piceae initial densities and the number of gouts on the evolutionarily naïve hosts, but no relationship for the evolutionarily native species, suggesting that the North American fir species do not differ in their susceptibility A. piceae. Understanding potential A. piceae resistance provides land managers with the ability to reforest areas with resistant native fir and ensure long-term viability.