May 29, 2013
Photo credit: Luther Caverly

A budworm’s barrier

The Eastern spruce budworm is a devastating pest in the Acadian forest, causing bouts of widespread mortality that not only affect the environment, but also the people and companies that depend on the trees to create forestry products and earn a living. Large-scale budworm epidemics change the forest landscape affecting the distribution n of other forest creatures including mushrooms, mammals and birds.

Carleton research performed by J. David Miller has revealed that nature itself has a barrier to the budworms that can reduce the use of costly pesticide treatments such as aerial applications.
In partnership with the forestry division of JD Irving, Limited, Dr. Miller’s research is mapping out natural fungi in the trees for the first time. Patents have been granted and more are pending for their collaborative work, building upon a partnership that has been underway since 1998.

It’s been known for decades that many plants have natural fungi inside of them, known as endophytes. In grasses, leaf fungal endophytes produce toxins that make the plants less appealing to herbivores including insects. With some clues from the literature, Dr. Miller and colleagues at the University of New Brunswick decided – some 25 years ago – to investigate the fungal endophytes of spruce.

The Eastern spruce budworm is a devastating pest causing bouts of widespread mortality

       

Working with JD Irving experts, Dr. Miller determined how to mimic nature in the greenhouse

The team found that some needle endophytes of white and red spruce make toxins that reduce the growth of budworms. When the insects eat the needles, the endophyte toxins slow their growth which makes the budworm more vulnerable to their predators, which include natural pathogens, parasites and birds. This in turn reduces the number of new larvae in the next generation, lessening the risk of epidemic conditions.

In undisturbed land, conifers acquire the fungal endophytes when seedlings grow on the forest floor under mature trees. Reforestation of land previously used for farming, logging, after forest fires or previous budworm damage began in New Brunswick in 1958.
Now some 30 million seedlings are planted by JD Irving which runs the most sophisticated seedling production operation in North America. Seeds come from orchards of superior trees collected over the years.  However, it turns out that seedlings grown in greenhouses are not exposed to endophytes when they are tiny, which in turn apparently has reduced the prevalence of the “good” endophytes.

Working with JD Irving experts, Dr. Miller determined how to mimic nature in the greenhouse. The next phase of the work was to determine whether the inoculation would persist in nature and whether the inoculated trees would be more tolerant to spruce budworm. There are now trees that are more than a decade old and the fungi are present throughout the tree as when they were seedlings. And no, the spruce budworm do not like the endophyte positive needles.

Combining the skills at the university and genetics at JD Irving, they have uncovered a hidden aspect of life in the forest

        

While working to protect these trees, Dr. Miller’s research has also helped biologists learn more about forest ecology. In spruce trees from Maine, New Brunswick and Nova Scotia, nearly all of the needle endophytes his team isolated were new to science.

This research began with two NSERC Strategic Grants to Professors John Findlay, Norman Whitney and Dr. Miller. The journey to understand this important aspect of forest ecology was possible only because of the technical excellence of Greg Adams’ team and the JD Irving seedling production operations in Sussex and Juniper, New Brunswick.
Combining the skills of biological chemistry at the university, and seedling production technologies and tree genetics at JD Irving, they have uncovered a hidden aspect of life in the forest. Dr. Miller believes that this understanding will benefit future generations of Canadians who want a sustainable, well-managed forest industry.

This aspect of Dr. Miller’s research at Carleton has received $1.74 million in direct and considerable indirect support from JD Irving since 1998 in peer-reviewed projects with contributions from the Atlantic Canada Opportunity Agency’s Atlantic Innovation Fund, the National Research Council’s Industrial Research Assistance Program and NSERC.

Watch: Improving tolerance to spruce budworm – naturally

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