EMERALD ASH BORER MONITORING & MANAGEMENT EAB Module 2

First Detector Training EMERALD ASH BORER MONITORING & MANAGEMENT EAB Module 2

Biology & Ecology Emerald Ash Borer: Biology & Ecology

Module Objectives The purpose of this module is to review the biology and ecology of an exotic, invasive tree pest called emerald ash borer (EAB).

Upon completing this module, you should be able to: • Describe the taxonomy of EAB • Identify the physical characteristics of EAB • Explain the life cycle of EAB • Name the plant hosts of EAB • Summarize the variety of EAB natural enemies

Taxonomy and Description

Phylum: Arthropoda Class: Insecta Order: Coleoptera Family: Buprestidae Genus: Agrilus Species: planipennis Binomial name: Agrilus planipennis (Fairmaire)

Adults are: • Iridescent green, wood-boring beetle • About 1/2″ long and 1/6″ wide • Flat-headed, creating D-shaped © Kent Loeffler, Cornell University holes in bark when emerging from pupation Emerald Ash Borer: Biology & Ecology

Life Cycle EAB adults are active from late May to mid-August. They live for about 3-4 weeks and feed on ash foliage. After mating, females lay 50-100 eggs, one at a time, on the bark of ash trees. They prefer to lay eggs © David Cappaert, Michigan State University, Bugwood.org where there are cracks so the hatching larvae can squeeze into cracks and bore into the bark. EAB density is lower in the smooth- barked upper crown areas and smaller diameter white ash. EAB eggs are about the size of a pinhead and hatch 7-10 days after being deposited. Eggs change color from creamy white to brown.

Life Cycle

June/July Summer/Fall Oviposition Larval growth

May/June Winter Adult Emergence Pre-pupae Ovary maturation

Early spring Pupation

© EAB eggs, Debbie Miller, USDA FS, Bugwood.org; larva, prepupa and pupa, David Cappaert, Michigan State University, Bugwood.org; EAB exit holes, Daniel Herms, the Ohio State University, Bugwood.org; EAB adult, David Cappaert, Michigan State University, Bugwood.org

Emerald Ash Borer: Biology & Ecology

White ash bark anatomy

Life Cycle After hatching, EAB larvae bore into the bark and feed on the tree’s phloem and cambium, eventually growing up to 2 cm in length.

The larval stage kills the ash tree because its feeding disrupts the tree’s flow of food and nutrients. Tree death occurs within 2 or © David Cappaert, Michigan State more years depending on pest pressure. University, Bugwood.org

EAB larvae overwinter as pre-pupae in the bark or within the outer ½ inch of the wood. They pupate the following spring. In colder regions or in earlier stages of infestation, the life cycle may take two years to complete.

Where to find EAB in ash

Life Cycle The pupal stage begins in spring and lasts about 28 days. Initial EAB adult emergence typically coincides with blooming of black locust (Robinia peseudoacacia), or about 450 GDD base 50 degrees F. © David Cappaert, Michigan State University, Bugwood.org Peak emergence is at about 900 GDD, usually in early June. Because their heads are flat on top, EAB adults create D- shaped holes in the bark as they emerge from pupation. These holes are about 1/8” wide.

Review How do EAB kill an ash tree?

Answer

When do adult EAB emerge?

Answer

Taxonomy and Life Cycle Summary

Stage Duration Comments Egg On and underneath bark; 7–10 days size of pinhead

Larva Underneath bark; most Typically 9–10 damaging stage; up to months 1.5″ long Pupa In outer wood in spring 28 days following overwintering

Adult Emerge when black locust 3-4 weeks blooms; size up to 0.5″

Emerald Ash Borer: Biology & Ecology

Hosts of EAB in its Native Range EAB is not a very serious pest in its native range because trees there have evolved with the pest and developed resistance to EAB. There are also natural enemies of EAB in Asia that help keep EAB populations in check. Manchurian ash (F. mandshurica), Chinese ash (F. chinensis), and Korean ash (F. rhynchophylla) are © Mark Whitmore, Cornell University native hosts for EAB in Asia.

Hosts of EAB in its Introduced Range

Because native ash trees in North America did not co-evolve with EAB, these species have not developed resistance to the pest. Even healthy trees are vulnerable to infestation.

In North America, EAB is capable of infesting all native ash trees (Fraxinus spp.). Fortunately, it has not been observed infesting any other types of trees. The most common ash trees in the US are: Cooperative Extension

• Green ash (F. pennsylvanica) Cornell • White ash (F. americana) • Black ash (F. nigra) • Blue ash (F. quadrangulata)

Hargrave, Rebecca

EAB Host Distribution in the US

Ash are an important part of eastern forests, sometimes becoming the dominant species especially in swamp forests and in old fields that are reverting back to forest. Emerald Ash Borer: Biology & Ecology

Basal Percentage of Ash by County

In New York Green ash is an important tree in the wetlands of the Lake Ontario Plain, in some counties representing up to 28% of the Basal Area. White ash is a common upland species in the Southern Tier and is an important timber species. Emerald Ash Borer: Biology & Ecology

Natural Enemies and Population Control Natural enemies and tree resistance keep native insect populations in check. When EAB was imported to the US it left all the natural enemies behind. However there are a few natural native to the US that have begun to exploit EAB as a food source.

EAB larvae are a favorite food of woodpeckers. Infested trees often are riddled with holes and scaled bark from

woodpeckers foraging on , Michigan State University, Bugwood.org larvae. Unfortunately, woodpecker feeding is not enough to suppress EAB. Cappaert

Natural Enemies and Population Control

A couple native parasitic wasps have discovered EAB (Antanycolus spp. and Spathius spp.) sometimes causing significant levels of mortality. They lay eggs in EAB larvae under the bark. A native predatory wasp, Cerceris fumipennis, has been found to capture EAB as well as other Buprestid beetles to provision the nest that they dig into the ground. They will lay an egg on the beetles and the larvae will consume © David Cappaert, Michigan State University, the prey. Bugwood.org Watching Cerceris nests to see what beetle species are being collected is very useful for detection, but the wasp does not kill enough EAB to effectively suppress its population.

To learn more about biological control of EAB, visit: http://www.emeraldashborer.info/Research.cfm#biological Emerald Ash Borer: Biology & Ecology

Natural Enemies and Population Control Scientists are in the process of implementing Classical Biological Control by searching for natural enemies where EAB is native. Three species look promising and are being released at selected sites in the US: • Spathius agrili: – parasitizes larvae • Tetrastichus planipennis: – parasitizes larvae • Oobius agrili: © Debbie Miller, USDA Bugwood.org Service, Forest USDA Miller, Debbie © – parasitizes eggs

To learn more about biological control of EAB, visit: http://www.emeraldashborer.info/Research.cfm#biological Emerald Ash Borer: Biology & Ecology

Review What trees in North America are commonly infested by EAB?

Answer

What two things keep populations of native insects in check?

Answer

Module Summary • There are four main life stages for EAB: egg, larva, pupa and adult. • Adult EAB emerge from trees in spring and early summer. • The larval stage is the deadliest to ash trees because larva feed on the tree’s phloem and cambium, which disrupts the flow of food and nutrients. • In North America, EAB is capable of infesting all plants in the Fraxinus genus. • The most common Fraxinus species include white, green, blue and black ash. • Natural enemies to EAB include woodpeckers and certain native, as well as, imported stingless wasps. These enemies have not been found to appreciably suppress EAB populations in North America but work continues. Credits Content adapted from the NPDN EAB modules prepared at Virginia Tech; published June 2010

Mark Whitmore, Forest Entomologist with Cornell University Department of Natural Resources, [email protected]

Prepared by Rachel McCarthy, NEPDN Education and Training Coordinator, Department of Plant Pathology and Plant-Microbe Biology, Cornell University, [email protected]