Chemical Ecology and Lure Development for Redbay Ambrosia Beetle
David Owens, Paul E. Kendra, Wayne Montgomery, Jerome Niogret, Elena Schnell, Tereza Narvaez, Daniel Carrillo, and Nancy Epsky
USDA-ARS, Subtropical Horticulture Research Station 13601 Old Cutler Road, Miami FL
E-mail: [email protected] [email protected]
Development of Attractive Field Lure 2009 - present
• Field tests (forest sites) • Lab and semi-field behavior
tests (Archbold Biol. Station, Lake Placid)
• Chemical sampling & analysis (Miami) – Lure emissions – Tree volatile emission
present
RAB Biology and Detection • One and done flight – uses
reliable cues to find hosts quickly – Harsh environment, limited energy
• Unique chemical ecology – No pheromone production – Are not attracted to fungal volatiles
long-range – Not attracted to ethanol (Hanula et al. 2008, Hanula & Sullivan 2008)
First Lures = Problematic Lures
• Volatile collection from redbay = 16 candidates (Hanula and Sullivan 2008)
• First lures contained several candidate terpenoids = Manuka (Myrtle bush) and Phoebe (laurel tree)
• Manuka lost attraction after 3 wk • Phoebe caught 6X more RAB, but no longer available
Phoebe Manuka Control
Bee
tles
/ tra
p / w
k
0
5
10
15
20
25
a
b
c
Xyleborus glabratus(mean + SE)
12-wk testHighlands Co., FL
(Kendra et al. 2012. J. Econ Entomol.)
Xyleborus glabratusWeekly Captures over Time
Week
0 2 4 6 8 10 12 14
Beet
les
/ wee
k
0
50
100
150
200
250
300
350
PhoebeManukaControl
Freeze
Bolt Boring Bioassay • No-choice tests to assess RAB boring
behaviors – 1-gallon bucket – 1 bolt plus 10-15 female RAB – Recorded # RAB boring – Replicated 5x
Kendra et al. 2013 FL Entomol.
RAB Flight Window • Multiple species
attracted to wood volatiles
• RAB flies earlier (27 collection dates, Apr-Oct 2011)
• Useful method for obtaining RAB in host-seeking behavior, the perfect stage to evaluate attractants
1600 1630 1700 1730 1800 1830 1900 1930 2000
Num
ber
of F
emal
es C
olle
cted
0
2
4
6
8
10
12
14
Time Interval
1600 1630 1700 1730 1800 1830 1900 1930 2000
Num
ber
of F
emal
es C
olle
cted
0
1
2
3
4
5
6
X. ferrugineus
X. glabratus
1600 1630 1700 1730 1800 1830 1900 1930 2000
Num
ber
of F
emal
es C
olle
cted
0
10
20
30
40
50
60
70
X. affinis
Kendra et al. 2012 Environ. Entomol.
sunset
Development of Field Lures for RAB
• Avocado bolts are just as attractive as Phoebe oil
Phoeb Guat W.Ind Mex Manuk Contr
Beet
les
/ tra
p / w
eek
0.0
0.5
1.0
1.5
2.0
X. glabratus(mean ± SE)
8-wk testAlachua Co., FL
a
aab
b
c c
(Kendra et al. 2011. J. Chem. Ecol.)
Bioassays and Field Tests
Time (hr)
0 5 10 15 20 25
Perc
enta
ge o
f Fe
mal
es B
orin
g
0
20
40
60
80
100 Silkbay (99%) – very attractive in field Swampbay/Redbay (91%) – so-so in field
Avocado (80%) – in lab, so-so in field
Camphor tree (50%) – very attractive in field Lancewood (44%) – not attractive in field
Live Oak (0%) – negative control
(Kendra et al. 2014 PLoS ONE)
Time (hr)
0 5 10 15 20 25
Perc
enta
ge o
f Fe
mal
es B
orin
g
0
20
40
60
80
100
>70% boring on cut end; trees most susceptible to attack after pruning or injury!
• Differential field attractiveness
Silkbay
Camph
or.
Cal. Bay
Sassa
fras
Swampa
y
Redba
y
Avoca
do
Lanc
ewoo
d
Spiceb
ush
Live O
ak
Contro
l
Nor
mal
ized
Cap
ture
s
0.0
0.2
0.4
0.6
0.8
1.0a a
bb b b
c c c
b
bc
Laurel Chemical Analysis
• Emissions of terpenoids from bolts correlated with RAB captures in field
• Major sesquiterpenes – α-cubebene (peak 2)
– α-copaene (peak 3)
Kendra et al. 2014 PLoS ONE
Evaluation of Other Essential Oils - 2012
• 7 essential oils – including cubeb, ginger, tea, angelica, orange
Cubeb oil = new attractant
(from berries of tailed pepper Piper cubeba)
X. glabratus (mean + SE)4-wk test (25 Apr - 23 May 2012)
Essential oil
Man Cub Phb Gin Ang Tea Ora Blk
Beet
les
/ tra
p / w
eek
0
2
4
6
8
10
12
aa
a
bb
bcc c
(Homemade lures – 2 ml oil)
Field Tests 2013 • Collaboration with Chemtica and
Synergy Semiochemicals – Field test comparisons with distilled
cubeb oil in bubble lure
Xyleborus glabratus (mean + SE)
8-wk Field TestFisheating Creek State Park
(8 Mar - 3 May 2013)
Cubeb bubble Manuka patch Control
Beet
les
/ tra
p / w
eek
0.0
0.5
1.0
1.5
2.0
2.5
a
b
b
12 wk Test, Highlands Co.
• Cubeb > phoebe > manuka • Cubeb field life of 3 months• Less expensive • Standard lure for RAB since 2015
(Kendra et al. 2015. J. Econ. Entomol.)
Cubeb Phoebe Manuka Control
Bee
tles
/ tra
p / w
k
0
2
4
6
8
10
12
14
16
18 a
b
c
c
Week
1 2 3 4 5 6 7 8 9 10 11 12
Beet
les
/ wee
k
0
20
40
60
80
100
120
140
160Cubeb Phoebe Manuka Blank
Further Improvement of RAB Lure (Collaboration with Synergy)
Goal = Identify primary attractant in cubeb lure
• Cubeb is a complex mix of terpenoids, at most 10% α -copaene and α -cubebene
• Separated cubeb oil into separate parts with different chemicals
• Choice tests and Olfactory response tests
• The two attractive parts were high in 1. α -copaene and 2. cubebene
New Lure Evaluations Two prototype lures prepared • Copaiba oil
(9% α-copaene, 0% cubebene)
• Proprietary oil product (50% α-copaene)
12-wk field test • Compare new lures to cubeb lure
(10% α-copaene, 10% α-cubebene)
50% Cop Cubeb Copaiba Control
X. g
labr
atus
/ tra
p / w
k
0
2
4
6
8
10
12
14
16 a
b b
c
Week
1 2 3 4 5 6 7 8 9 10 11 12X.
gla
brat
us /
wk
0
20
40
60
80
100
120
140
160
180
50% CopCubebCopaibaControl
A
B
Kendra et al. J. Pest Sci. 2016
α -Copaene Gradient in Trunk
• Beetles use vision and chemistry to concentrate attacks on tree trunks
• α -cubebene and α -copaene concentration greatest in the trunk, lowest on twigs/leaves
RAB in Avocado
• What about avocado? – RAB is relatively rare in avocado – Wilt-infected trees do not
necessarily have RAB infestation (Carrillo et al. 2012).
– Can we detect RAB in avocado?
We don’t see this in avocado
Detection of RAB in avocado - 2015 • Deployed traps in a grove at the beginning of an
outbreak – α -copaene, α -copaene + ETOH, cubeb + ETOH, silk
bay
• Only α -copaene lures captured RAB! (but not many)
• α -copaene also captured fewer non-targets
One year later…
Wood seeking missile • Host choice: look, smell, and taste right • Beetle is detectable at new wilt-sites • α -copaene lure could possibly be used to alert
a problem • RAB does not breed well in avocado • Initial infestation from RAB, infestation spread
from because of other factors
But Wait…There’s Even More
• Euwallacea fornicatus = shot hole borer
• picked up with α -copaene • First discovered in FL in 2006
– Avocado 2010
Lure Evaluation - 2014
• Daniel Carrillo tested commercial ambrosia beetle lures – Ethanol UHR – Ethanol + Chalcogram – Ethanol + Conophorin – Ethanol + Cubeb
– Ethanol + Quercivorol
• Quercivorol used by the folks in CA, traps
capture hundreds of beetles/week
But Wait…There’s Even MORE!
Field Testing Lures 2 wk test, Spring 2016, site A
• α -copaene, quercivorol, combination, and blank
Quer + Cop Quercivorol Copaene Control
Bee
tles
/ tra
p / w
eek
0
10
20
30
40
50
60a
b
b
c
Field Testing Lures 4 wk test, Summer 2016, site A
• Population slightly lower
• Combo lure more attractive
Quer + Cop Quercivorol Copaene Control
Bee
tles
/ tra
p / w
eek
0
5
10
15
20
25
30a
bc
b
c
Field Testing Lures 8 wk test Summer 2016, site B
• Low population • Wilt affected
grove • Combo more
attractive than either querc. or α -copaene
• Combo is additive or synergistic
Quer + Cop Quercivorol Copaene Control
Bee
tles
/ tra
p / w
eek
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6 a
b b
b
Host Attraction Hypotheses and Current Research
• Quercivorol – shorter range attractant – Produced by Euwallacea -infested wood
• α -Copaene – longer range attractant – Alert to a possible host
• Others? – Bioassays for attractive alternative hosts – Identify additional terpenoids – Guide lure evaluation
Questions?
