How we learned from a costly mistake, the ash borer.

HOW WE LEARNED FROM A COSTLY MISTAKE, THE ASH BORER.
Story by Pat Kerr


The tiny insect - properly called Agrilus planipennis or EAB - can fly, but there is no reasonable way it made that distance on its own. Hot spots are camp grounds and gas stations, showing clearly that its movement was human-supported... likely on firewood. EAB is a cute insect that shimmers in metallic shades of green and pink, when seen under a light. It plays dead, and the males have hair on their chests. It is the type of insect that can fill the child in us all with wonder.


The dying trees are ash or Fraxinus, a common native forest tree family but also a major part of urban landscaping, since the demise of the elm in the 60's. The wood is commonly used for baseball bats, hockey sticks and aboriginal basket weaving. It is valuable environmentally, economically and for places like Winnipeg, almost impossible to replace. The species decline is costing North America millions, and our tax dollars are only beginning to pay, as the black ash was added to the endangered species list this winter.


With all the bad news, there is significant good news happening behind the headlines.


"This is the most exciting project, I've ever been involved with," said Melissa Spearing, Seed Program Coordinator, Forest Gene Conservation Association. "As more people see the value in natural woodlots, we can maintain what we know are stable ecosystems. This is an incredible proactive project. Things we've always seen can disappear in a moment."


Spearing, who works with Forest Gene Conservation is part of one of Canada's newest projects to protect the ash species. Together with the Invasive Species Centre and the National Seed Centre in New Brunswick, they are working to collect ash seed from as many areas as possible, before the genetic variations are lost forever. They are asking people to report high levels of ash seed on wild trees, growing near a roadway (to allow them easy access so they can reach more areas during the short seed season) to inaturalist.ca.


"The mast seed looks like dirty socks hanging from the trees," said Spearing.


The seed will be used for research and replanting after researchers find successful control agents.


In the almost twenty years, since EAB was discovered here, researchers have studied bushels of options. They have monitored squirrels (who peel the bark off ash trees to get to the larvae), woodpeckers (the presence of whom remains one of the best ways to identify an EAB-infested tree,) fungi, viruses, and parasitoids. They've tried eradication, control, and strung funnels together in ash trees to dust the EAB with killing agents, while monitoring the insect's mating behaviour. As a result, we now know a lot about EAB and the hundreds of native, beneficial insects that look like EAB.


We know, EAB is here to stay. We are going to learn to live with it.


One of the projects to help ash trees and our cities live with the EAB is the release of parasitoids, or biocontrol. It is the idea that all species are kept in check by something else. When a species is removed from those controls, it becomes a problem. Reintroduce the controls, and the new species can become a beneficial citizen, or at least not a problem. In reality, this doesn't need human intervention - it will happen eventually, but it could take many decades.


Researchers went to China, the native home of the EAB, and brought back EAB enemies. In China, our American ash is used as a reforestation tree. It is also a majestic tree in the Beijing arboretum. Our ash is not a long-lived species in China, but it is doing better than it is doing in Canada. The difference seems to be a few tiny, non-stinging wasps. How many species of wasp, we don't know - but so far they've found four, and two are being released in Canada, after years of careful testing. (The different species have different lengths of ovipositors, so they lay their eggs in trees with different thicknesses of bark, or different aged trees. None of them can protect large, mature ash.)


I have never personally seen O. agrilli, an EAB enemy. It is just too tiny. T. planipennisi is the largest of the beneficial insects being released and has goggly eyes and iridescent wings. Unlike the beautiful EAB, it isn't the traditional definition of cute, but it is also so tiny, and delicate that it could not be considered scary. None of the parasitoids being released have a stinger. They also have no venom. Their back end is an ovipositor used to lay eggs under bark.


While this project is ongoing on both sides of the border, other US researchers have found a few of the 1% of surviving ash trees have some ability to withstand EAB. They are cross-pollinating these trees, and searching for why these few trees are thriving. The resulting seedlings are being tested for their response to EAB, and the results are beyond exciting. They could be releasing ash with a level of resistance to EAB for replanting, this decade.


A Canadian discovery is a product called TreeAzin, for high value trees. This natural pesticide is injected by professionals into the tree, where it kills the larvae feeding inside the tree. To work correctly, it must be used at the correct time of year, and before the tree is heavily infested. Reapplication is done in alternate years, during low pressure times, and annually, when infestation in the area is high.


What took a hundred years to do for the chestnut (decimated by chestnut blight) and fifty years for the elm (decimated by Dutch elm disease) has happened in less than twenty years for ash, because we've learned from past mistakes - but we are still learning.


In the meantime, we shouldn't move firewood. Never move firewood from your cottage to your home, or from your home to your cottage. Do not take firewood when you go hunting, and do not bring it home. Burn firewood in the region where the tree lived. Just as importantly, join citizen science projects like inaturalist.ca, and when you see a tree dying with an unusual insect, take pictures and send it in. Ordinary people who pay attention have saved - and can continue to save - the entire continent millions of dollars. We have learned from our mistakes.


Photographer Dan Kerr learned his craft in his dad's darkroom and progressed to taking crime scene photographs for the Ontario Provincial Police. Today, he is focused on his 15-year project of building an airplane.