Catching the Wind: New Tool Forecasts Forest Pest Movements
Building the advanced model was a monumental feat. Through partnership, new resources were brought together: Canadian Forest Service analyst Rémi Saint-Amant integrated the new spruce budworm model into the Canadian BioSIM platform, which forecasts seasonal biological phenology, such as insect life stage development. Scientist Jacques Régnière, also with the Canadian Forest Service, mined Canadian archives for data that could better relate moth flight patterns to temperature profiles above the tree canopy. University of Wisconsin scientist Matthew Garcia contributed advanced computational resources to model millions of hypothetical moth flights and related those to weather surveillance observations.
In the battle against forest-devouring pests, knowing your foe’s next move is everything. The spruce budworm is one such pest. Native to North America, its population can explode, bringing widespread loss of needles, or defoliation, to vast tracts of spruce-fir forests. For forest managers, knowing where spruce budworm is heading is critical to combating its destructive effects. Thanks to a powerful new online tool—the Spruce Budworm Atmospheric Transport Model (SBW-ATM)—managers can now forecast when, where, and how these moth swarms will emerge, travel, and land.
For Brian Sturtevant, a research ecologist with the USDA Forest Service, the project began with a simple question: why hadn’t anyone developed a model to predict spruce budworm dispersal?
The spruce budworm is named for its habit, as a tiny emerging caterpillar, of tunneling into the buds of spruce and fir trees to eat their tender new growth. In eastern Canada and northern U.S. states like New Hampshire, Maine, and Minnesota, large outbreaks can strip the needles from millions of acres of trees, making it one of the most destructive forest insects in the region. After feeding, the larvae become moths whose main job is reproduction—launching in huge numbers to colonize new areas and repeat the cycle. The widespread destruction has a severe economic toll, degrading timber resources and affecting supply economies of fir and spruce.
“Spruce budworm moths are known for their ‘mass exodus’ behavior,” says Sturtevant. “They launch in billions and are carried on the wind. Early in my career, I wondered if we could use meteorological data to project their long-distance dispersal.”
In 2005, Sturtevant initiated a cross-border study of outbreak dynamics in the “Border Lakes” region of Ontario and Minnesota. Working with Canadian Forest Service scientist Barry Cooke and university partners on both sides of the border, the team examined how forest landscape conditions shaped the timing and location of budworm outbreaks. While dispersal wasn’t the study’s main focus, the question remained: could spruce budworm movement be modeled?
Canadian researchers had previously studied the aerobiology of spruce budworm, linking moth flight behavior to atmospheric conditions like temperature, wind speed, and precipitation. Meanwhile, USDA Forest Service meteorologist Gary Achtemeier had created models that linked insect flight to near-surface weather. These models could be combined with meteorological tools the agency was using to model other phenomena, such as fire weather and smoke plume dynamics. These different efforts provided a promising foundation for a new tool.
By combining ideas from both fields, Sturtevant and his collaborators designed an experimental version of the Spruce Budworm Atmospheric Transport Model (SBW-ATM), testing it in the Border Lakes region.
Following years of growing destruction from spruce budworm outbreaks further east, US and Canadian researchers met in Quebec City in 2014 for a "Canada-US Forest Health Initiative" symposium. From this collaborative meeting, the USDA Forest Service, Canadian Forest Service, and the University of Wisconsin began a formal partnership to combine independent research into one joint effort to predict spruce budworm’s movement.
“Partnering amongst all of these groups was key to developing this tool,” says Sturtevant.
The new online model is already proving useful to forest managers in both Canada and the United States. State of Maine foresters and researchers alike have been using the tool for several years, while land managers in Minnesota— who are responding to the aftermath of a shifting 20-year outbreak—are now learning to use the new tool.
Looking ahead, Sturtevant sees potential to adapt the model for other questions or forest pests.
“If the necessary data is collected, this tool could possibly be adapted for spongy moth or jack pine budworm,” says Sturtevant. Additionally, this existing application might offer further insights into long-term spruce budworm outbreak patterns.
“It has been professionally rewarding to see this germ of an idea mature into such an advanced tool,” reflects Sturtevant. Powerful and innovative tools like the Spruce Budworm Atmospheric Transport Model help the Forest Service promote healthier forests, more resilient communities, and stronger rural economies.