Emerald Ash Borer (Agrilus planipennis)

OBSERVATION: While in Brampton, ON over the winter holidays, I spotted a few trees with the symptoms listed below. I did some research and asked the locals, who mentioned it's the emerald ash borer.

BACKGROUND: The emerald ash borer is a beetle that is native to Asia and was first discovered in June 2002 in Windsor, Ontario (Ontario, 2016). The first sighting of the beetle was suspected to have been transported from Asia in packaging materials (Invading Species, 2016).

The emerald ash borer feeds on native and introduced Ash species (Fraxinus spp.), as well as native ash trees, with one incident of it attacking the fringe tree in Ohio (Toronto and Region Conservation, 2016). The larvae feed on the cambium of the host tree and burrow tunnels between the bark and wood, which results in starving the tree of water and nutrients (Ontario, 2016). The larvae take 1-2 years to reach maturity, pupate in the tree, and then emerge as adult beetles from June to August. (Ontario, 2016).

The emerald ash borer is difficult to control because host trees show limited signs of infestation until they are nearly dead. Symptoms include reduced leaflet size, yellowish colouration, and leaf dieback beginning at the crown of the tree. Later symptoms include epicormic branching, cracked bark, and significant branch dieback. (Invading Species, 2016). This impacts local biodiversity because many species of birds, insects, and some mammals rely on tree growth in urban areas.

There are a few treatments for ash trees including the introduction of wasps, removal, and injection with TreeAzin insecticide which only lasts a maximum of two years (BioForest Technologies Inc., 2016). Canadian Forest Service have recently began releasing two species of parasitoid wasps from Asia (Tetrastichis planipennisi and Oobius agrili) in Ontario, which have been successfully released in Michigan, to control Emerald Ash Borers (Credit Valley Conservation, 2016).

For more information in Canada please visit the Canadian Food Inspection Agency's webpage on emerald ash borer's: http://www.inspection.gc.ca/plants/plant-pests-invasive-species/insects/emerald-ash-borer/eng/1337273882117/1337273975030

For more information about the issue in Brampton, as well as the budget please visit the Corporation of the City of Brampton's webpage: http://www.brampton.ca/en/City-Hall/meetings-agendas/Committee%20of%20Council%202010/20120613cw_F5.pdf

PHOTOS: Figure 1. The physical appearance of the emerald ash borer (Canadian Food Inspection Agency, 2016) Figure 2. Larvae feeding and burrowing distinctive “S-shaped” tunnels (Invading Species, 2016)

CONSULTS: Taylor Scarr, Ph.D., Provincial Forest Entomologist, Forest Sustainability and Information Section, Crown Forests and Lands Policy Branch, Ontario Ministry of Natural Resources and Forestry)

Taylor Scarr "Hello Natasha, Thank you for your April 21, 2016 email to Minister Mauro requesting feedback on your post regarding emerald ash borer in Brampton, Ontario. Your request was forwarded to me to respond on behalf of Minister Mauro. I would like to offer the following comments for your consideration: 1. The report is concise and well written. This is a large topic which could fill volumes of reports in order to describe the situation. You’ve done a good job of keeping your observations brief and to the point. 2. I suggest the following: i. Change Fraxinus. Genus and species names are either Latin, or Latinized words from other languages. The convention is to write them in italics or to underline them. ii. Larvae feed on the cambium. The cambium is the live tissue just under the bark. When these cells divide they form xylem towards the inside of the tree, and phloem and bark to the outside. Since this is the only part of the trunk that is actually alive, it is most nutritious from the insect’s perspective. Hence this is where this and many other insects prefer to feed. Phloem, which is just under the bark, is only a few cells thick and transports food from the leaves to the roots. Xylem, which is the woody part of the stem and consists of hollow cells connected end-to-end like straws, transports water from the roots to the leaves. The tunnelling by the larvae in the phloem cuts off the flow of food to the roots. The roots starve, die, and can no longer send water to the leaves. The leaves and branches start to die from lack of water. The feeding by the larvae in the outer layer of the xylem also reduces some of the flow of water up to the leaves. iii. Beetles do not go directly from the larval stage to the adult stage. Like moths and butterflies, they must first go through a pupal stage. EAB makes a pupal chamber by tunneling about 1 cm into the xylem or outwards into the bark if it’s thick enough. The pupa changes into an adult beetle which then emerges through the bark, leaving a D-shaped exit hole about 4 mm across. The adults may re-attack the same tree, or migrate to new trees. Timing of emergence varies geographically and depends on local climate. In Ontario, adult emergence begins in June, peaks in July, and is usually over by the second week of August. There may be a few stragglers into September. iv. You have listed the symptoms of EAB attack. That’s good. Symptoms are the tree’s response to attack by EAB, but they may not be exclusive to EAB. That is, drought or other insects can cause the same symptoms. One symptom which is pretty diagnostic for EAB is heavy woodpecker feeding with multiple probes into the bark and flaking off the bark by the birds. No other insect elicits this behaviour of woodpeckers on ash trees. If you see an ash tree heavily attacked by woodpeckers, you can be pretty sure it has EAB in it and that that is what the birds are after. You may also wish to list the signs of EAB attack. These are things created by the beetle and are more reliable for verifying EAB attack. These include the D-shaped exit holes, the serpentine (S-shaped) larval tunnels under the bark, and feeding on the leaf margins by the adults to gain a protein meal needed for maturing their eggs. v. Use of TreeAzin has several benefits. 1) it can be used to keep high value trees alive until the EAB population collapses after killing >99% of the surrounding ash trees; 2) it can buy time for research into new controls or for developing management techniques; 3) it can buy time for the biocontrol program to work (i.e., the wasp releases you mentioned); and 4) municipalities can protect trees and keep them alive over decades, thereby spreading (i.e., amortizing) their tree losses and budget costs over decades rather than incurring the costs of tree removal and replacement over a much shorter period of 5-10 years of peak EAB infestation. vi. While the wasps have successfully established in Michigan and elsewhere, there is insufficient evidence to conclude that they kill enough EAB to keep ash trees alive. The latter would be a more appropriate measure of effectiveness, rather than just the success of being released and surviving. It will take many years, likely decades, of releases and monitoring before we will have evidence of the effectiveness of the wasps in controlling or mitigating EAB impacts. 3. You may wish to round out your narrative by mentioning the unavoidable costs in the millions of dollars faced by municipalities, conservation authorities, and private landowners in cutting and replacing the ash trees that inevitably die as EAB invades an area and causes >99% tree mortality within about 10 years. Cities like Brampton often post their management plans on-line, or the council minutes posted on-line can give an estimate of the municipal budget allocated to EAB. 4. A few other points to consider: i. When EAB is first found in an area, it’s always more abundant and more widespread than it first appears. ii. It often takes time for local managers and decision makers to react, such that tree mortality is often well-advanced before action is taken. The best programs begin well before the insect arrives. iii. EAB is here to stay. Land managers need to adjust to it being a permanent part of the landscape. Hopefully the native and introduced parasitoids will eventually help mitigate the impacts, but it will be many years before we know how effective they will be. iv. Diversity of species and genetic sources can create more resilient urban forests that are less vulnerable to losing a high proportion of their trees should an invader like EAB arrive and kill most of the trees in a single genus. Native tree species are often best-adapted to the local climate, and will not themselves become invasive trees that naturalize and dominate the local ecosystems. v. Although EAB can fly and spread on its own, most long distance spread has probably been by people moving infested firewood. Firewood is also a pathway for other invasive forest insects and diseases. People should avoid moving firewood. It should be bought and consumed locally to reduce the risk of spreading invasive species. This is a good report, Natasha, on a very large and complex problem. You have done an excellent job of condensing it down to salient points that would be of interest to someone who wanted an overall perspective on emerald ash borer. Your language is clear, and your style is informative. I hope you find my comments helpful. Thank you for your email. It’s always encouraging to know others share an interest in the health of our forests.

Taylor"

Mike Brubaker The main LEO reviewer said this: " Nice observation and description. Not sure why the photos did not turn out better. This is another potential set up for a project - like 'emerald ash borer watch'. You need to find a lead organization(s) (host) with consultant. Then LEO could help crowd source observers."

References BioForest Technologies Inc. (2016). TreeAzin Systemic Insecticide. Retrieved from http://www.bioforest.ca/index.cfm?fuseaction=content&menuid=18&pageid=1026 Canadian Food Inspection Agency (2016). Agrilus planipennis (Emerald ash borer) - Fact Sheet. Retrieved from: http://www.inspection.gc.ca/plants/plant-pests-invasive-species/insects/emerald-ash-borer/fact-sheet/eng/1337368130250/1337368224454 Credit Valley Conservation (2016). Emerald Ash Borer. Retrieved from http://www.creditvalleyca.ca/your-land-water/emerald-ash-borer/ Invading Species (2016). Emerald Ash Borer. Retrieved from http://www.invadingspecies.com/invaders/forest/emerald-ash-borer/ Ontario (2016). Emerald Ash Borer. Retrieved from https://www.ontario.ca/page/emerald-ash- borer Toronto and Region Conservation (2016). Emerald Ash Borer. Retrieved from http://www.trca.on.ca/the-living-city/land/habitat-protection-and-regeneration/emerarld-ash-borer.dot