What is an EAB’s Favorite Meal and Why is it Important?

Therese M. PolandDeborah G. McCulloughAndrea C. AnulewiczDeepa S. Pureswaran

EAB Host Range

China - Fraxinus spp.

Japan & Korea – Juglans - Pterocarya- Ulmus

North America - ??

Why Study Host Range?

• Know what species are at risk

• Understand susceptibility of urban & forest trees

• Improve survey and detection

• Enhance management options

• Propogate and enhance resistance

Assess EAB feeding preference & larval development

(1) Alternate species of concern

(2) Compare North American Species

(3) Stressed & vigorous trees

(4) North American & Asian ash

Host Range Objectives

No-choice lab bioassay

Caged adult female & male with wood section & ash leaf.

American elm, black walnut, shagbark hickory, hackberry & privet tested.

Reared until females died.

After 4 weeks, eggs counted & bark dissected to assess 1st stage larval galleries.

(1) Alternate Species of Concern

EAB eggs on or just under bark

Mean no. eggs per cm2 no-choice test; n = 5

No.

egg

s pe

r cm

2

0.00

0.03

0.06

0.09

0.12

0.15

Evaluated 1st stage larval galleries

Density of galleries per 100 cm2 no-choice test; n = 5

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Gre

en A

sh

Whit

e Ash

Black

Ash

Blue

Ash

Privet

Jap.

Tre

e Lil

ac

Am. E

lm

Blk. W

alnu

t

Hickor

y

Hackb

erry

a a

a

a a

b b b b b

No-choice lab bioassay

Black ash

Black walnut

Caged-Stem Bioassay

Screen cages confined 3 pairs of beetles on each tree

Dead beetles replaced June-Sept.

Stems dissected: 4 blocks in Nov.6 blocks in March

Repeated in 2004 & 2005

0

20

40

60

80

100

120

Green Ash White Ash Tree Lilac Black Walnut

2004

2005

A

AB B

aa

b b

EAB Gallery Density per m2 on Caged Stem Bioassay

Host Range Field Tests

Ash, Elm, Walnut, Hickory, Hackberry logs & drain pipe set on t-posts at 4 sites. Adult landing rates monitored using Tanglefoot. Logs dissected.

0

20

40

60

80

100

120

140G

reen

ash

Whi

te a

sh

Elm

Blac

k w

alnu

tH

icko

ryH

ackb

erry

Pipe

Landing Rates of EAB AdultsT

otal

adu

lts

0

10

20

30

40

50

60

Green

Ash

Whit

e Ash

Am. E

lm

Blk. W

alnut

Hickor

y

Hackb

erry

Drain

Pip

e

a

a

b b b b b

Gallery Density in Logs Strapped to T-Posts

Host Range Field Tests

Green ash, elm & walnut logs suspended in heavily infested ash tree canopies; Will EAB females make a mistake?

Logs dissected.

Mean density of EAB galleries per m2 in Suspended logs

Green ash 195.5 ± 49.5

Elm 0.0

Walnut 0 ± 0

3 logs per tree on 5 trees in 2 sites; 30 total logs

Host range field test: 1st & 2nd stage larvae inserted into green ash, elm & black walnut

Larval insertion: green ash, elm & black walnut trees & logs

Alternate Species Results

• Adults will oviposit on alternate species under no-choice conditions.

• Oviposition “mistakes” occur but rare.

• 1st stage larvae fed readily on ash species; a few larvae attempted to feed on other species but development impaired.

(2) Preference Among North American Ash Species

2003: canopy dieback was significantly higher in green ash than white ash

2004: canopy dieback increased in both species, still higher in green ash

2005: canopy dieback reached 100% for most green ash and rose sharply in white ash

Green vs. White ash trees 4 neighborhoods over 3 years.

Similar pattern for exit holes and woodpecker attacks.

Preference Among North American Ash Species

White vs. Blue ash trees 2 woodlots over 2 years.

2004: exit holes and woodpecker attacks were significantly higher in white ash than blue ash

2005: exit holes and woodpecker attacks increased in white ash but not blue ash and the difference was more significant.

Host selection and feeding preference on ash spp.

• Green – F. pennsylvanica

• Black – F. nigra

• White – F. americana

• Blue – F. quadrangulata

• European – F. excelsior

• Manchurian – F. mandshurica

Experimental set up

beetles released

• Host selection - landing – number of beetles on each ash species

counted every 2h during the day for 48h

• Feeding preference – amount consumed– Leaves were scanned before and after the

experiment– Amount fed determined

species

00.20.40.60.8

11.21.41.61.8

22.2

green black white blue European Manchurian

ab ab

bc

a

c c

females

00.2

0.40.6

0.81

1.21.4

1.61.8

2 a

bb

c c

c

males

No

. o

f b

eetl

es o

n f

oli

age

(mea

n

+S

E)

Host selection - landing

0

2

4

6

8

10

12 ab

ab

a

cd

bc

d

males

0

2

4

6

8

10

12

14

green black white blue European Manchurian

a

aa

a

b

b

females

Am

ou

nt

of

foli

age

con

sum

ed (

%)

species

Feeding preference

(3) Stressed and Vigorous Trees

Trap trees with different stress treatments:Girdled, herbicide, methyl jasmonate, wounded

Plantation study: Girdled, fertilized, and control trees of different ash species

(4) Beetle performance on American vs. Asian Species

• Raised beetles (n=40) on green and Manchurian ash until they died

• Leaves changed and retrieved each week

• Measured amount consumed, weight gained / lost over two weeks and longevity

Foliage consumption

02468

101214161820

pro

po

rtio

n c

on

sum

ed (

%)

0

2

4

6

8

10

12

14

16

tota

l am

ou

nt

con

sum

ed (

cm)2

a

b

a

b

green Manchurian green Manchurian

Beetle performance

0

1

2

3

4

5

6

green Manchurian

wei

gh

t lo

ss a

t ag

e 2

wee

ks

(mg

)

0

2

4

6

8

10

12

14

16

18

20

green Manchurian

lon

ge

vity

(d

ays

)a

aa

a

Results

• Total amount and proportion of foliage consumed was greater in beetles fed on green ash compared to Manchurian

• No difference in weight or longevity

What may be going on?

• Higher nutritive value of Manchurian ash?

• Presence of anti-feedants in Manchurian ash?

• Higher consumption of green ash by larvae — mortality of trees in North America?

Compounds Identified andQuantified in Different Ash Species

• hexanol• E-2-hexenal• Z-3-hexenol• E-2-hexenol• butoxyethanol• Z-3-hexenyl acetate• hexyl acetate• E-β-ocimene• nonanal / linalool• nonatriene• Z-E-α-farnasene

GreenWhiteBlackBlueEuropeanManchurian

0

2

4

6

8

10

12

14

16n

g /

g d

ry w

t ti

ssu

e

b b

bb

aZ-3-Hexenol

0

500

1000

1500

2000

2500

ng

/ g

dry

wt

b

aa a

a

a

Z-3-hexenyl-acetate

-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5

3

-3 -2 -1 0 1 2 3 4

green

black

white

blue

European

Manchurian

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

-3 -2 -1 0 1 2 3 4

stressed

healthy

Hybrid study• North American ashes are preferred relative to

Chinese ashes• What would happen with hybrids?• Crossed F. americana with F. chinensis to

obtain two putative hybrids chiam1 and chiam2• Tested beetle landing and feeding on the four

genotypes• Compared volatile profiles by aeration

Host selection by landing and feeding preference

F. americana F. chinensis Chiam 1 Chiam 2

Hybrid study: Beetles released in cages

Hybrid study: landing

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

1 2 3 4 5 6 7 8

F. americanaF. chinensisChiam 1Chiam 2

Observations over time

Mea

n n

um

ber

of

bee

tles

Hybrid study: feeding

amo

un

t co

nsu

med

(cm

2)

(me

an +

SE

)

0

5

10

15

20

25

30

0

2

4

6

8

10

12

14

16

F. americana F. chinensis Chiam 1 Chiam 2

pro

po

rtio

n c

on

sum

ed (

%)

(me

an +

SE

)

species

aa

a a

a

a

a a

Hybrid study: Aerations

Super-Q

Compounds quantified

• hexanal• e-2-hexenal• z-3-hexenol• e-2-hexenol• z-3-hexenyl acetate• hexyl acetate• e-β-ocimene• nonanal / linalool• farnesene Gas chromatography

Hybrid study:

Comparison of volatiles

F. americana

0

5

10

15

20

25

30

35

40

F. chinensis

0

510

15

20

2530

35

40

chiam1

05

10152025303540

chiam2

05

10152025303540

hexan

al

z-3-

hexen

ol

e-2-

hexen

al

e-2-

hexen

ol

z-3-

hexen

yl_a

ceta

te

hexyl

_ace

tate

e-oci

men

e

linal

ool

nonanal

farn

esen

e

Am

ou

nt

(ng

/ g

dry

wt)

Hybrid study - Results

• Landing and feeding: no significant differences

• Hybrids have taken on some characteristics from F. americana parent

• Volatile profiles of hybrids different from either parent – may not be simply inherited

Conclusions• EAB feed and develop in all ash species• No evidence of larval survival or

development on any non-ash species• EAB prefer Green>Black>White>>Blue

ash• EAB prefer N. American ash to Asian ash• Hybrids may be intermediate and volatile

characteristics are not simply inherited• Surveys should focus on preferred trees

(green ash)• More research needed to develop

resistance and attractive lures