A Natural Insecticide to Protect Ash Trees

By Emmanuelle Brière
April 2013

An eco-friendly insecticide jointly developed at Natural Resources Canada is being used as one of the key tools helping to protect trees from the emerald ash borer.
Photo of an emerald ash borer larvae

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A larva forming a gallery in the wood of an ash tree.

The Neem tree produces organic compounds that have been used in India for centuries as an effective way of protecting crops from insect pests. Now, this tropical broadleaf evergreen has been enlisted to help fight a new invasive species attacking trees in Canada: the emerald ash borer.

Using extracts from the Neem tree seed as a key ingredient, scientists from Natural Resources Canada (NRCan) worked collaboratively with BioForest Technologies Inc. to develop and commercialize a botanical insecticide called TreeAzin.

“TreeAzin was specifically developed for control of invasive wood boring insect pests,” says Dean Thompson, NRCan Research Scientist, who’s pursuing research initially spearheaded by now retired scientist Blair Helson. “It is particularly effective against invasive pests like the emerald ash borer when used as a protective method on lightly infested trees.”

A Natural Insecticide

Photo of TreeAzin injection system

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Systemic injection of TreeAzin to protect an urban ash tree from the emerald ash borer.

The TreeAzin formulation contains a natural product called Azadirachtins, originating from Neem tree seeds. The insecticide interrupts insect larval moulting occurring under the tree bark. Thompson notes that the compound significantly reduces larval growth, development and feeding, and also reduces fertility and egg viability when adults feed on the foliage of treated trees.

Scientists from Natural Resources Canada’s Great Lakes Forestry Centre and BioForest Technologies also jointly developed the injection system to deliver the insecticide. In short, the system consists of pressurized canisters which are connected to the tree in a manner similar to an intravenous system. Once connected, the canisters release the insecticide under the tree’s bark and directly into the tree’s conductive tissues, and it moves upwards with the flow of water and nutrients.

“Because TreeAzin is injected directly into the tree, it negates any potential human or environmental exposure, thus strongly mitigating any risks,” says Dean. “Tests have shown that azadiracthins have generally very low toxicity to mammals, birds and other non-target organisms, which also enhances its suitability for use in urban and environmentally sensitive areas.”

A Tool for Municipalities

Photo of infested and non-infested ash trees

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An untreated ash tree (foreground) with TreeAzin treated ash trees (background) in Oakville, Ontario. Photo Credit: BioForest Technologies Inc.

Many cities throughout central and western Canada have a high proportion of ash in their urban forests. Some municipalities facing emerald ash borer infestation including Oakville, Ontario have been using TreeAzin to protect individual ash trees.

“Oakville has the most aggressive municipal EAB management program in Canada, with 75 percent of the municipal tree canopy treated with TreeAzin under the Ash Tree Treatment Program as of 2011," says John McNeil, Manager of Forestry Services, Parks and Open Space in Oakville municipality. "The product has been very effective at conserving the ash canopy, with all but one of the 5,700 treated trees remaining alive.”

Recently registered for use across Canada, TreeAzin allows for the treatment of urban trees in the early stages of an infestation. Researchers are confident that trees that are highly valued by homeowners and urban foresters can be effectively protected using this technique while other methods of control are developed. TreeAzin is now being explored as a possible treatment against other invasive insects, such as the brown spruce longhorn beetle.

“Researchers at Natural Resources Canada continue to explore the possibility of other biological control methods such as predators, parasites or diseases with the goal of sustained control of this destructive pest,” says Thompson.

For more information on control methods being developed by NRCan scientists, visit Canadian Forest Service website.

To read about related articles, see Forest Pests.

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