Early intervention research focuses on monitoring, detecting and treating small areas of relatively low but growing populations (hots spots) of spruce budworm before infestation or epidemic levels occur.

Sharing results is important. As part of this research project, the Healthy Forest Partnership wants to keep everyone up to date on the process and progress of the research program.

Update

A spruce budworm infestation is approaching New Brunswick from the Gaspe Peninsula. Research is focused in targeted areas in northern New Brunswick, where detailed sampling is identifying “hot spots” that need to be treated to help control budworm populations.

The severe uncontrolled outbreak in Quebec grew by over 3.9 million hectares in 2020, reaching over 13.5 million hectares in size (New Brunswick has 6 million hectares of forest). Not only is the outbreak growing in size, but it is on the border of New Brunswick.

Based on monitoring, populations of spruce budworm have increased in New Brunswick. The projected treatment area in 2021 will increase from about 32 500 hectares in 2020 to about 91 000 hectares. While there has been an increase in SBW populations, researchers are encouraging that the rise has been much lower in New Brunswick than in Quebec and suggests that the Early Intervention Strategy is working. Scientists believe that the EIS Strategy aided by natural enemies,  are mainly responsible for keeping the population in check. However, the threat of a budworm outbreak is not over as the outbreak in Gaspe continues just across the New Brunswick border.

Research Projects

Sharing results is important. As part of this research project, the Healthy Forest Partnership wants to keep everyone up to date on the progress of the research program.

The early intervention research focuses on monitoring, detecting and treating small areas of relatively low but growing populations of spruce budworm before they reach infestation or epidemic levels.

Here’s what we are currently doing

The early intervention strategy (EIS) option aims to either interrupt or delay the course of a spruce budworm outbreak through targeting ‘hot spots’ or ‘epicenters’ when population densities are still very low. These epicenters are thought to serve as emitter sites from which adult SBW moths migrate, enhancing infestation rates in surrounding low density populations, and ultimately increasing densities above levels that can be controlled by natural enemies.

For EIS to work, we must address several significant knowledge gaps:

  1. how large do treatment areas have to be to offset the impact of immigrant SBW moths from nearby outbreaks (i.e., north of the NB border)?
  2. are there potential negative consequences of EIS, in particular for natural enemies of SBW in treated areas? Does EIS have positive effects for habitats and conservation?
  3. how to identify potential epicenters and predict how they will spread?

To date, the EIS approach appears to be working. Key successes include reducing SBW populations in treated blocks and avoiding serious defoliation and resulting wood supply losses.

The research program is divided into 10 constituent projects, as described below.

Investigators

B. Cooke (GLFC) & J. Régnière (AFC) B. Sturtevant, H. Thistle, J. Charney, G. Achtemeier (USFS) R. Saint-Amant, Y. Boulanger (LFC)

R&D Topics Addressed

Develop a SBW population dynamics predictive model that would describe spatial and temporal patterns of outbreaks (local dynamics and moth migration), and allow testing of management strategies through simulation on an appropriate spatial-dynamics platform.

Investigators

D. MacLean (UNB), C. Hennigar (UNB), J. Gullison, A. Dick (NBDERD), L. Amos-Binks (FPL), U. Vepakomma (FP-I)

R&D Topics Addressed

Incorporate into the SBW DSS effects of hardwood content in reducing SBW defoliation & a new SBW population model appropriate for EIS projections. Refine optimum operational blocking heuristics and use in planning EIS treatment blocking. Measure defoliation and tree response in plots in QC & NB and develop refined DSS impact relationships. Develop new growth loss and mortality factors.

Investigators

G. Cormier (FPL) & A. Willett (JDI)A. Morrison (FPL), L. Amos-Binks (FPL)R. Johns, M. Stastny, E. Owens (AFC)

R&D Topics Addressed

Conduct pesticide (Btk and tebufenozide) and pheromone trials of EIS to suppress SBW populations. Determine best practices for application of insecticides to lower cost of large scale EIS & increase available sessions for insecticide application. Test effects of application timing, application rates, material, rainfastness, aircraft track spacing, meteorological conditions, etc.

Investigators

D. Pureswaran (LFC) & R. Johns (AFC)V. Martel (LFC) P. James (U. Montreal) E. Owens, M. Stastny, I. DeMerchant, J. Allison J. Bowden (AFC)C. MacQuarrie, J.-N. Candau (GLFC)

R&D Topics Addressed

Continue outreach & public engagement in the Budworm Tracker program. Use genetics to assess population connectivity among sites. Provide a genetically-informed model of effective dispersal capacity. Assess whether low-density populations (e.g., southern NB, NS) are independent populations or whether they are in fact the offspring of migrants from the outbreak epicentre in QC.

Investigators

M. Cusson (LFC) & A. Smith (U. Guelph)E. Eveleigh R. Johns (AFC), V. Martel, P. Tanguay (LFC)

R&D Topics Addressed

Refine & enhance species-specific and hierarchical molecular assays to assist in identifying SBW mortality agents. Evaluate rates of parasitism and parasitoid composition in the SBW larvae collected from the EIS efficacy component Evaluate levels of parasitism and pathogen loads in L2s from branches collected in fall or winter. Develop a simplified, “bulk” version of the assays.

Investigators

P. Silk & E. Eveleigh (AFC), L. Roscoe, P. Mayo, W. MacKinnon, G. LeClair, M. Williams, Gl. Forbes, M. Brophy, K. Burgess, R. Lamb (AFC)

 

R&D Topics Addressed

Another method under development is the use of pheromones to disrupt spruce budworm mating. Pheromones are airborne signals used by insects to locate one another. One of the major roles of pheromones is to attract spruce budworm to one another so they can mate. Our mating disruption research seeks to disrupt this mate location by applying pheromone in the canopies of vulnerable balsam fir and spruce trees. When adult spruce budworm enter the canopies, they will be confused by the airborne pheromone, and unable to find partners. No mating means less caterpillars feeding on the needles of trees in the following year. Pheromones occur naturally and are species-specific, meaning that the spruce budworm pheromone only affects this insect and therefore poses no risk to humans or other animals.

Investigators

E. Emilson (GLFC) & M. Stastny (AFC), M. Gray, S. Heard, K. Kidd, T. Linnansaari (UNB)R. Johns (AFC)L. Venier (GLFC) 

 

R&D Topics Addressed

Determine the impacts of SBW outbreaks, and conversely, experimentally test the potential benefits of EIS treatments, on riparian canopy and understory vegetation, riparian bird habitat & communities, water quality and hydrologic functioning of forest streams, structure and functioning of aquatic and riparian food webs, and critical fish habitat and fish health in forest streams.

Investigators

J.N Candau(GLFC), M. Stastny & E. Moise (AFC), J. Bowden, R. Johns, M. Rhainds, A. Roe (AFC)

R&D Topics Addressed

Improve forecasting and decision-making essential for successful implementation of EIS under changing environmental conditions, by better forecasting of the timing of SBW development (phenology), and improved forecasting of SBW performance and survival in the context of EIS treatments.

Investigators

U. Vepakomma (FPI), S. Haddad, G. Costanzo, D. Cormier (FPI), R. Johns (AFC), D. MacLean (UNB), D. Kneeshaw (UQAM)

R&D Topics Addressed

Develop a generalised defoliation detection method, apply and test it for SBW defoliation (current and cumulative defoliation) and implement for a medium resolution publicly available satellite data.

Monitoring and Detecting

The first step to managing spruce budworm in the context of an early intervention strategy is to detect and monitor where populations are rising before they reach relatively high densities.

Spruce budworm populations are monitored and detected in several ways:

  1. Aerial defoliation surveys in July to detect defoliation. Prolonged defoliation (4-7 years) cause the trees to die and turn red. These areas are detected by observers in an airplane and sketched on a map to define where defoliation occurred.
  2. Surveillance from the ground for signs of spruce budworm feeding and the presence of spruce budworm larvae and other life stages such as pupal cases. Observations of either budworm feeding or life stages would be evidence of elevated populations (for more information on what spruce budworm looks like, please visit this link).
  3. Pheromone and light trapping of adult moths provide baseline information on local spruce budworm population densities. See our map for current information.
  4. Branch collections for overwintering larvae provide forest managers with a forecast of budworm density in the following year, which can be used to estimate defoliation level. The overwintering larvae are often referred to by scientists as second instar budworm or “L2” for short. See our map for current information.