British Columbia's Northern Interior Forests: Warren Root Collar Weevil Stand Establishment Decision Aid

Abstract

Warren root collar weevil (Hylobius warreni) is a commonly occurring insect found in most of British Columbia and as far north as the Northwest Territories. This weevil affects many tree species and is found in forest stands of any age, although its impact as a disturbance agent is most important in lodgepole pine stands. Engelmann and white spruce are also common hosts, but incidence levels have not been high enough with these species to cause reforestation issues. Incidence levels in lodgepole pine stands commonly exceed 30%, although mortality levels are generally far less and occur in younger stands (5-20 years of age). Recent research suggests that a link exists between stands affected by mountain pine beetle (MPB) and root collar weevil. In one study, the incidence of weevil-attacked trees was elevated in young plantations adjacent to mature stands that had sustained high levels of MPB-caused mortality. An understanding of the weevil's biology and the identification of high-hazard stand conditions for both insect species are essential to successfully avoid regeneration issues. Most treatments involve mitigation measures applied during stand establishment. The Stand Establishment Decision Aid (SEDA) format has been used to extend information on a variety of vegetation and forest health concerns in British Columbia. The two-page SEDA presented in this extension note was developed to summarize information that northern forest managers will need to manage the impacts of the Warren root collar weevil. The following pages describe susceptible stand types, weevil biology, hazard ratings, forest productivity considerations, and appropriate management practices. A resource and reference list that readers can use to find more detailed information is also included. Most reference material that is not available online can be ordered through libraries or the Queen's Printer at: www.qp.gov.bc.ca