Sticky cards for monitoring dispersing balsam woolly adelgid (Hemiptera: Adelgidae) crawlers in subalpine fir stands

Abstract

Balsam woolly adelgid (BWA), Adelges piceae, is an invasive insect colonizing true fir in North America. Following its recent range expansion into Utah, BWA has caused significant mortality of subalpine fir (Abies lasiocarpa). The first instar (crawler) is the only motile life stage and is responsible for dispersal among trees, usually by wind. Due to BWA’s small size, detection and monitoring is challenging. In this study, monitoring for dispersing crawlers using sticky cards was compared to a more labor-intensive bark sampling method in four northern Utah stands with the goal of identifying a simplified approach for crawler detection. Sticky card orientation (horizontal or vertical) for optimal crawler capture and a mesh covering for bycatch reduction were tested. Sticky cards were effective in detecting dispersing crawlers and counts generally tracked unsettled crawler densities observed on bark samples. Horizontal card placement had higher crawler captures than vertical cards, and the addition of a mesh covering on the card reduced bycatch as compared to uncovered cards. Results provide evidence that sampling with horizontally-placed, mesh-covered sticky cards can be an effective tool for detection and monitoring of dispersing BWA crawlers, thus supporting phenology research and decision-making for optimal timing of BWA management.

Citation

Rideout, Elizabeth; Alston, Diane G.; Bentz, Barbara J. 2024. Sticky cards for monitoring dispersing balsam woolly adelgid (Hemiptera: Adelgidae) crawlers in subalpine fir stands. Gen. Tech. Rep. RMRS-GTR-442. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 11 p. https://doi.org/10.2737/RMRS-GTR-442