The brown spruce longhorn beetle (BSLB) is an invasive forest insect from Europe that infests spruce trees. Larvae consume the phloem that transports food to the roots, weakening the tree. Once infested, trees are reinfested every year until they die, a process that can take one to five years.
BSLB was discovered in Halifax in 1999, but has been established in Nova Scotia since at least 1990. It likely arrived in wood packaging aboard container ships.
The insect has been under regulatory control by the Canadian Food Inspection Agency (CFIA) as a quarantine pest since 2000. The CFIA surveys eastern Canada for BSLB, using pheromone-baited traps developed by the Canadian Forest Service (CFS) of Natural Resources Canada at the Atlantic Forestry Centre. The CFIA also regulates the movement of high-risk spruce products from infested areas to reduce the artificial spread of BSLB, and supports Natural Resources Canada (NRCan) research on BSLB ecology and mitigation.
In Europe, BSLB infests Norway spruce weakened by root rots, defoliators or mechanical damage (e.g., from wind and lightning). Recent research has confirmed that BSLB infests red spruce in Canada as well, preferring to attack and performing better in stressed rather than healthy trees. Ongoing trials are testing the effect of attack density and tree health on susceptibility to colonization by BSLB.
Research by CFS-Atlantic indicates that BSLB infested and killed about 30% of spruce basal area from 2008 to 2012 in sites near Halifax.
Mature spruce forests in Canada, especially those under stress from defoliator outbreaks (such as spruce budworm) or drought, are at risk of BSLB infestation and accelerated mortality.
Without efforts to suppress BSLB along the leading edge of the infestation (lying in a 60- to 80-kilometre radius around Halifax) or in outlier populations, the insect will continue to spread.
While practical means of suppressing BSLB in natural forests are yet available, NRCan research is yielding some promising results. Scientists at CFS-Atlantic have shown significant suppression of BSLB by both mass trapping and pheromone-mediated mating disruption. A collaborative research project between CFS-Laurentian and CFS-Atlantic is testing auto-dissemination of a native insect fungal pathogen for suppressing BSLB. In this strategy, BSLB are attracted to a pheromone-baited trap, where they become contaminated with the fungus and escape, spreading the fungus within the BSLB population through mating. CFS-Atlantic is also testing best practices for management of BSLB.
In addition, in partnership with university researchers, NRCan is investigating BSLB population ecology. CFS-Laurentian is leading research to investigate interactions between BSLB and the native community of bark beetles and associated organisms in spruce forests.