1. 2 Exotic Invasive Insects Radically Altering the Ecology of Eastern Deciduous Forests Hemlock Wooly Adelgid (HWA) Emerald Ash Borer (EAB) - Bill Rucker PBIO Ohio University 2013

2. Native to Japan, and east Asia Introduced to Pacific Northwest in early 1920s Both eastern hemlocks on moist rocky ridges, ravines and hillsides 50% of the geographic range of eastern hemlock impacted by HWA (2007)

3. feeds on both Tsuga canadensis and T. caroliniana attacks all age and size trees sucking mouthparts feed on xylem at base of needles needles turn gray-green then fall off limb dieback trees usually die within 4-10 years

4. Adelges tsugae 2 generations per year females reproduce asexually 2 kinds of adults winged Sexuparae – spruce sexuales probably die wingless Progrediens – hemlock sistens (overwintering) both produce cottony white ovisacs progrediens hatch in April crawlers roam to suitable site 4 instars (molts) mature into adults in June produce ovisacs in June/July sisten crawlers feed briefly aestivate August – October resume development – 4 molts ovisacs and eggs by March Life Cycle

5. Hemlock Wooly Adelgid Life Cycle From Cheah et al. 2004

6. Spreading 20-30 km/year, vastly increased populations Can tolerate temperatures below – 65° F Dispersal (esp crawlers) by wind, birds, deer and humans Hemlocks are a foundation species – create cool, damp shaded microclimate for unique plant communities important stream temperature regulator provide habitat and food resources for winter wildlife

7. More likely to spread north as climate warming advances Decreases in primary productivity and increase in detritus Subsequent changes in decomposition and mineralization Change in competition, forest structure and composition

8. Chemical and IPM Controls Careful moving logs, firewood, bark chips from infested to uninfested areas Extra water during drought periods Prune dead/dying branches Fertilize after recovery – not during horticultural oils or insecticidal soap Systemic insecticides All impractical for woodlots

9. Silvicultural Options Hemlocks as likely to be infested with HWA whether in hemlock-dominated or in mixtures with other hardwoods or conifers No pre-emptive harvesting – may kill hemlocks with resistance How mixed is the stand? Other species? Level of infestation? Slope? Beside a stream? Decide on goals – timber, wildlife habitat, public safety, successional trajectory and rate, water quality?

10. Do Nothing slow, gradual successional change no soil disturbance snags and woody debris create many microhabitats unlikely to move infested wood around Heavy Cut (> 50% BA ) recover timber value heavy slash possible damage to residual trees possible fast hardwood / conifer regeneration possible invasives problem

11. Biological controls and hybridization programs Some occasional predators of HWA in eastern North America None with significant effect on HWA populations Introduced predators: Coccinellid ladybug beetles (Pseudocymnus tsugae Sasaji and McClure n. sp.) -both larvae and adults prey on all stages of HWA 3 beetles of the genus Scymnus -prefer eggs Developing hybrid hemlocks with Tsuga caroliniana, not with T. canadensis T. caroliniana a likely relic species 108 suitable candidate hybrids for testing

12. Emerald Ash Borer – Agrilus planipennis Native to Asia and eastern Russia Transported on nursery stock and wood products w/ bark Adults feed on leaves, larvae tunnel through cambium and sapwood Interrupts movement of nutrients and water in phloem Kills tree within 2-4 years

14. 16 native species of ash threatened by EAB Comprise >7% hardwood stand mix, 5.5% including conifers Ashes are important components of rich, mesic woodlands, cove forests, swamps, floodplain and bottomland forests

15. Buck, J.H. Emerald Ash Borer Program Manual

17. Adults can fly 8-10 m Females >200 eggs in lifetime Eggs laid on rough bark surfaces and in crevices Larvae enter into phloem 4 instars pupate during winter

18. Consequences of spread and damage: 2002 – first detected in southern Michigan 2008 – over 50 million dead trees 2012 – over 100,000 sq mi. reported in 16 states Over 7.5 billion ash trees on U.S. forest lands Additional 30-90 million ash trees in urban areas Estimates of over $25 billion in chemical treatments, removal/replacement in urban areas (25 states) 114 million board feet/year ash produced in eastern U.S. worth $25.1 billion In it’s native range also infests Elms, Walnuts and Hickories – but not here yet

19. Eradication is not possible Monitor for symptoms thinning crowning die-back of branches woodpecker feeding (flecking) epicormic branching D-shaped exit holes Zig-zaggy galleries Monitor for adults

20. Various jurisdictional boundaries of quarantines

21. Physical, Chemical and Biological Control DON’T TRANSPORT Cut, chip, compost (or burn) any wood with bark close to site Evidence of native parasites on EAB, but no significant reduction in populations 3 hymenopteran parasitoids (of eggs and larvae) from China approved for release in U.S. 3 systemic chemicals: -Imidacloprid – soil injection/drench -Dinotefuran – soil drench, bark spray -Emamectin benzoate – trunk injection

22. Hemlock Wooly Adelgid (HWA): Questions About how many years will a hemlock tree survive after being infested with HWA? What are the 2 kinds of adults that HWA may have and what are the major differences between them? What is the overwintering generation of the HWA and describe it. Name 2 ways that hemlock trees are considered a foundation species and how may their widespread death alter other forest functions? If you have a woodlot with hemlock trees, why is it not advised to pre- emptively harvest them if they are free of HWA?

23. Emerald Ash Borer (EAB): Questions What are the two primary ways that EAB has spread throughout the eastern U.S.? What is the way that EAB kills the host ash tree and what signs can you look for that a tree is infested? Describe and/or draw the EAB life cycle. Name two major consequences of the catastrophic loss of ash trees. After continued monitoring of infestation by EAB, what are two important controls to prevent or treat further infestation?