EAB will continue to spread in the U.S. & Canada. Emerald Ash Borer: If only we knew then what we know now

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1 Emerald Ash Borer: If only we knew then what we know now Fraxinus sp. July 2002: Green beetles collected from declining ash trees in Detroit, MI & Windsor, Ontario are identified as Agrilus planipennis Fairmaire. EAB larvae likely arrived in the U.S. in solid wood packing material originating in China. EAB is a secondary pest in its native range in Asia; attacks very stressed or dying Asian ash trees. Very little information about EAB available in Deborah G. McCullough, Professor Depts. of Entomology & Forestry Michigan State University Container ship Solid wood packing material 2016: EAB in 25 US states & 2 Canadian provinces. Hundreds of millions of ash trees in urban, rural, forest & riparian areas in the U.S. have been killed by EAB. Economic costs of EAB greatly exceed costs of other major invasive forest insects in the U.S. Annualized marginal damages in $ millions USD Government Households Timber Property Private Federal Local Spent values land EAB EAB will continue to spread in the U.S. & Canada More than 8 billion native ash trees in U.S. forests. Millions of ash in urban, residential & rural areas. All 16 native ash species in the U.S. can likely be colonized by EAB. Gypsy moth Hemlock adelgid Aukema et al PLoS One Vol. 6:

2 EAB is also killing ash in Russia & threatens Europe 2007: EAB identified as cause of severe ash mortality in Moscow. Baranchicov et al. 2008; Mozolevskaya et al : EAB has killed almost all ash in Moscow & vicinity; EAB populations in 11 provinces of European Russia Orlova-Bienkowskaja 2013; Straw et al Oct. 2013: BBC News: Emerald ash borer beetle on the march across Europe. EAB from the US has raised fears about the future of ash trees in Europe Moscow What we ve learned EAB biology in North America Leaf feeding Beetles feed on ash leaves 5-7 days before mating begins. Females feed for another 7-14 days before they begin to lay eggs. Each female can lay eggs; Adults have 3-6 week life span. Egg hatching Eggs hatch & larvae feed in serpentine galleries on phloem & cambium, from mid summer to fall. Complete 4 instars. Most larvae overwinter as prepupal larvae in the outer sapwood or outer bark. Pupate in spring. PP larva Pupation New adults emerge from D-shaped exit holes from mid May to mid or late June. Trees colonized from the top down, so exit holes are often difficult to see. Adult L2, L3 & L4 larvae in Sept. Extensive larval galleries in the phloem also score the outer sapwood. Galleries disrupt transport of nutrients & water. High larval densities lead to canopy decline & eventually the entire tree dies. EAB detection, delimitation & survey are very difficult Determining EAB distribution is complicated by: 1. No external signs or symptoms at low larval densities. 2. Two-year EAB life cycle in healthy, newly-infested trees. 3. No long range pheromones. 4. Girdled & debarked ash effective, but not often used. 5. Canopy traps & lures are not highly effective. 4 th instar & gallery High density feeding Dieback Mortality USDA APHIS canopy trap Double-decker trap Girdled trees - debarked 2

3 Traps & lures have improved but detecting low densities EAB remains a problem. Data from the SLAM (SL.ow A.sh M.ortality) Pilot Project show relative efficacy of girdled trees vs. baited purple canopy traps. Many EAB outlier sites originated from transport of infested ash nursery trees, logs or firewood; Difficult to detect until EAB densities build to moderate levels. Probability of Detection Mean larvae per tree Girdled trees USDA APHIS baited purple canopy traps Mercader et al Resurrected from the Ashes: Reconstructing the initial EAB invasion through dendrochronological analysis When & where did EAB arrive in North America? How did ash mortality spread? 1998: ~ 24 mi : ~ 4094 mi 2 Siegert et al In 5 years, the area encompassing ash trees killed by EAB increased 170-fold. Sites are typically infested for at least 4 years before symptoms become apparent or trees decline. Therefore, EAB likely was established in southeast Michigan by the early 1990 s & perhaps earlier. Siegert et al Diversity & Distributions Long distance dispersal: Most females lay eggs within 100 meters of emergence point. But a few females (<5%?) disperse 1-5 km (?). Long range dispersal is unpredictable. Leads to patchy distribution. Mercader et al. 2009, 2011, 2012 McCullough et al. 2011; Siegert et al Long distance EAB dispersal: We know little about why or how often or how far EAB females go. Actual EAB distribution is likely 4-6 km or more beyond detection threshold, even 6 years after establishment. New satellite populations usually simmer for at least 4 years before any tree decline is noted. Mercader & McCullough 2012a, 2012b; Mercader et al. 2014; Siegert et al

4 Once EAB populations build, high rates of ash decline & mortality usually occur over a 3-4 year period. Landscape ash in Toledo, Ohio before & after EAB June 2006 August 2009 Impacts of EAB in the US Economic Ecological Cultural Social Photos courtesy of D. Herms, OSU Economic costs: nurseries, municipalities & homeowners Landscape ash trees that are not protected with effective insecticides are nearly always killed by EAB. Dead trees are hazards. Tree removal is costly & unpleasant. Ann Arbor, MI Flint, MI Kenosha, WI Ohio Michigan Michigan Chicago Minnesota Our ability to effectively & economically protect landscape ash trees from EAB has improved dramatically. Few effective options available in the early years of EAB Cover sprays not popular (exposure, drift, non-targets) Early systemic insecticide products inconsistent Treated trees often died 2-3 years after untreated trees. Night Day 2016: Improved systemic products & application methods Safari basal trunk spray TreeAzin TREE-äge Soil drench; 2x rate TREE-äge 4

5 Relatively new systemic insecticide options Products (active ingredient) TREE-äge - trunk injection (emamectin benzoate) TreeAzin - trunk injection (azadirachtin) Safari - basal trunk spray (dinotefuran) Azasol - trunk injection (azadirachtin) Imidacloprid products - 2x rate soil drench or soil injection Treat 2-3 years 1-2 years 1 year 1-2 years 1 year Information on insecticides for EAB & ash protection available free at Multi-state extension bulletins Protecting landscape ash trees Economics favors treating landscape ash (not removal). McCullough & Mercader 2012; Vannatta et al 2012; Kovacs et al Retains ecological benefits: (stormwater capture, shade). Predictable treatment costs allow for long-term planning. Avoids catastrophic death curve & neglect of other urban forest activities (pruning, planting, etc.) Many municipalities adopting integrated management strategies (e.g., SLAM - SL.ow A.sh M.ortality). Urban tree inventories: assess location, size & condition. Effective systemic products, e.g., TREE-äge, TreeAzin, used to protect valuable landscape ash. Ash destined for removal can be girdled in spring, then destroyed in fall or winter; girdled trees act as trap trees. Strategic, long-term planning for eventual replacement of ash & diversification of urban forest. Boulder, CO - illustrates a block with & without ash trees Haves & have-nots: environmental justice issues When resources for treating ash trees are not available, ash die & become hazard trees; strains municipal services. Impacts of EAB in the US Economic Detroit Saginaw Ecological Cultural Social Lansing 5

6 EAB ecology - interspecific variation in host preference Ecological impacts of EAB in forested areas will vary, depending on ash species & relative abundance White Ash Green Ash Fraxinus americana Black Ash F. pennsylvanica Blue Ash F. nigra F. quadrangulata EAB host preference & impacts in forests No evidence to date that site or stand variables consistently affect ash mortality. No effective silvicultural options to EAB-proof stands. Ash seeds don t persist in seed banks. Blue ash (healthy) is relatively resistant; 60-70% survival. White ash is intermediate; survival varies from < 10-90%. Green ash & Black ash are highly preferred & vulnerable. Black Ash Fraxinus nigra Common in bogs & swamps in 19 northern states; Slow growth & infrequent seeding. Cultural resource for Native American & 1 st Nation tribes Anulewicz et al. 2007, Burr & McCullough 2014, Klooster et al. 2014, Knight et al. 2014, Tanis & McCullough 2012, Tanis et al Black ash: Highly preferred & most vulnerable EAB host. Galleries extend further horizontally than on other ash species; each larva injures more area. EAB & Black Ash: Ecological & Cultural impacts Ecological impacts of black ash mortality will be severe. Few silvicultural options for black ash. Cultural & spiritual resource of several Native American & First Nation tribes in jeopardy. Some seed collection & preservation efforts underway. A few tribes treating selected seed trees with TREE-äge. 6

7 MSU novel ash plantation F. excelsior appeared to be highly preferred EAB host European ash Impacts of EAB in the US Economic F. ornus colonized but less preferred EAB host F. angustifolia Raywood ash trees were killed by EAB in west MI in 2012 Flowering ash Ecological Cultural Social Social & political aspects of EAB Municipal officials must deal with unhappy residents. Local resources often overwhelmed. EAB tends to attract Rats! Communication - critical aspect of life with EAB EAB affects almost everyone & everyone needs info National EAB website: Housed at MSU & funded by the USDA Forest Service Robin Usborne EAB.info serves as a portal to all things EAB At least 500,000 visits annually since 2006 & 70-80% are first-time users. Social media helps drive traffic to the website (Twitter, Reddit, Facebook) Mobile access comprised 34% of visits in 2015 EAB University Webinar Series Funded by USDA Forest Service & housed at Purdue University (IN), Michigan State University & Ohio State University Since 2013, 55+ webinars ( 45 minutes) have been presented by experts from on broad range of topics. Webinars can be downloaded & viewed at EAB.info or on the EABU YouTube channel. 2015: More than 450 people viewed 10 webinars live & 2019 users accessed EAB.info to view recorded sessions. 7

8 EAB affects almost everyone & everyone needs info EAB outreach efforts by land grant universities & state agencies facilitate neighborhood organization (e.g., for ash tree treatment), municipal programs, seed collection, woodland management, ash utilization, regulations & more. EAB & Firewood: changing behavior across the US Lots of ways to spread the word about EAB Most recent forest invaders, including EAB, lack long range pheromones. Innovative detection options needed! Traps & attractants more use of visual cues such as light, color, motion, etc. to attract adult insects? Hyperspectral imaging to identify infested trees? Acoustic signals to to attract pests or ID infested trees? Citizen science: e.g., sentinel tree networks EAB surface J. George, ARS EAB larva - acoustic signals Eyes on the Forest: Building Awareness to Increase Early Detection of Invasive Forest Pests in Michigan 8