Post on 28-Mar-2015
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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