Distribution of the Balsam Woolly Adelgid in Idaho

Abstract

The balsam woolly adelgid (Adelges piceae) was introduced from Europe to northeastern North America in about 1900. In 1983, it was discovered infesting fir trees in Idaho. Since then, aerial and ground surveys have documented its spread in Idaho over an area of approximately 14,000 mi2 (8,960,000 ac). It now covers most of the central one-third of the state. Aerial surveys in 1997 and 1998 identified about 125,000 ac of host type with dead or damaged trees. Subalpine fir (Abies lasiocarpa) is a critical species in many high elevation areas. The effects of the balsam wooly adelgid on aesthetics, hydrology, and other ecological values can be very important. The adelgid is likely to continue its spread throughout subalpine fir forests of Idaho and neighboring states. West. J. Appl. For. 15(4):227-231,

Development of a Dispersal Model for Balsam Woolly Adelgid,Adelges piceaeRatzeburg (Hemiptera: Adelgidae), to Facilitate Landscape-Level Management Planning

“…Occurrence. Subalpine fir is the dominant host of balsam woolly adelgid in Idaho [5] although grand fir has been reported to be a supportive host [13]. In the Rocky Mountain region, subalpine fir stands grow in full sun sites of cool high-elevation subalpine meadows and in microsites where pockets of cold air collect [14].…”

“…Based upon the Euclidean distance between current infestations of balsam woolly adelgid, 57% of the infestations were within 0.3 km of other infestations (Table 1). Prior reports of the adelgid in Idaho have primarily focused on range expansion over relatively large areas and less so on the distances between individual infestations (i.e., [5]). Nearly all (97%) balsam woolly adelgid infestations located by the flight surveys within our study area were located within 5 km of other infestations.…”

“…Within the study area, subalpine fir occurred in disjunctive patches at higher elevations. Prior work on range expansion by balsam woolly adelgid in Idaho concentrated on examining large geographic areas [5]. However, variogrambased spatial distance analysis showed that the majority of infestations were located in relatively close proximity (within 5 km) to other infestations (Table 1).…”

“…While grand fir, A. grandis (Douglas × D. Don) Lindley, is present throughout much of the infested area in Idaho, the adelgid is established on subalpine fir, A. lasiocarpa (Hook.) Nutt., where it is responsible for significant levels of mortality [5]. Infestation of firs by the adelgid results in structural changes within the host tissues.…”

Climate Risk Modelling of Balsam Woolly Adelgid Damage Severity in Subalpine Fir Stands of Western North America

“…lasiocarpa ) in California, Oregon, Washington and British Columbia [10, 11, 12, 13, 14, 15, 16]. Today the insect continues to disperse eastward and northward across Idaho, western Montana and British Columbia [17, 18, 19, 20, 21] where it is causing significant damage to subalpine fir stands. BWA is anticipated to continue to spread throughout the range of subalpine fir and cause significant decline of this important high elevation species.…”