Meet the emerald ash borer, a tiny green beetle that has killed millions of ash trees in southern Ontario, parts of Quebec and the northeastern United States since it was first detected in the Windsor, Ontario area in 2002. Experts believe this flying beetle, which measures only 8.5 to 14 millimeters in length, arrived in North America in wood packaging from Asia.
The eggs laid on the trunk of the tree under a bark chip or in a bark crevice, the tiny larvae when it emerges from that egg chews its way down through the bark to the surface of the wood. So it occurs in that interface between the wood and the bark and the larvae starts to form a gallery there. Well that tissue in that area is very important for transporting nutrients up and down the tree and transporting water up the tree. And so, as the larvae feed they damage some of those vessels that transport the fluids and that eventually girdles the tree and causes the death of the tree.
Signs of an emerald ash borer infestation on a tree include a thinning crown, long shoots growing from the trunk or branches, small D-shaped emergence holes and S-shaped tunnels under the bark filled with fine sawdust.
Also the trees in Asia have co-evolved with the insect and have developed certain chemical and different kinds of defences that they can use to prevent infestations or at least limit them. In North America our trees don't have those defences so they're pretty susceptible to attack and we also don't have a lot of those parasites and predators, we have some and they have moved on to emerald ash borer but they don't seem to be able to keep the insect in check.
Glue-coated green prism traps, installed in the canopy of ash trees, are being used to conduct area-wide surveys for early detection of emerald ash borer infestations. The traps use a natural chemical that is a component in a tree's leaves as a lure to capture the beetles.
In a test forest outside Sarnia, Ontario, Dr. Lyons and his colleagues are conducting biological experiments which may help in controlling the spread of the emerald ash borer using natural enemies such as native fungal pathogens.
We've been developing some trapping techniques where a beetle is trapped into a live trap, it passes through the trap, picks up a dose of the fungus and then flies off and the fungus that it picks up is lethal to that beetle. But we're also hoping it will transmit that fungus to its mates or other members of the species that are chewing on the leaf's surfaces and maybe even transmit that to their eggs and affect the next generation.
By attracting the insects to a trap rather than spraying a pesticide over the entire tree, researchers are targeting emerald ash borers but not significantly affecting other species inhabiting the ash tree.
We can all help slow the spread of the emerald ash borer in Canada by not moving firewood. On its own, the beetle doesn’t move very far. Hiding in firewood, though, it can travel vast distances.
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