Sex pheromone of browntail moth, Euproctis chrysorrhea (L.): Synthesis and field deployment

Article abstract of DOI:10.1021/jf073161w

The browntail moth, Euproctis chrysorrhea (L.), is native to Eurasia, where periodic outbreaks result in defoliation of forest, shade, and ornamental trees. In addition to the damage caused by defoliation, human contact with larval urticating hairs often

Full text of DOI:10.1021/jf073161w

2452 J. Agric. Food Chem. 2008, 56, 2452–2456
Sex Pheromone of Browntail Moth, Euproctis
chrysorrhea (L.): Synthesis and Field Deployment
ASHOT KHRIMIAN,*,† DAVID R. LANCE,§ MEIER SCHWARZ,†,‡
§
BARBARA A. LEONHARDT,†,‡ AND VICTOR C. MASTRO
Invasive Insect Biocontrol and Behavior Laboratory, Beltsville Agricultural Research Center,
Building 007, Room 301, Agricultural Research Service, U.S. Department of Agriculture, 10300
Baltimore Avenue, Beltsville, Maryland 20705, and USDA, APHIS, PPQ, CPHST Otis Laboratory,
Building 1398, Otis ANGB, Massachusetts 02542
The browntail moth, Euproctis chrysorrhea (L.), is native to Eurasia, where periodic outbreaks result
in defoliation of forest, shade, and ornamental trees. In addition to the damage caused by defoliation,
human contact with larval urticating hairs often results in severe dermatitis. Hence, tools for monitoring
and controlling the moth populations are desirable. The female-produced sex pheromone of the
browntail moth was identified previously, but the synthesis had not been published. This paper reports
the synthesis of the pheromone of the browntail moth, (7Z,13Z,16Z,19Z)-docosatetraenyl isobutyrate,
using in a key step a Wittig olefination of (6Z)-13-(tetrahydo-2H-pyran-2-yloxy)tridecenal. Field trapping
studies were conducted with rubber septa and string formulations of the pheromone and included
dose-response, pheromone purity, and dispenser-aging trials. It was found that traps baited with 250
µg of pheromone of 91–94% isomeric purity (main impurity presumably being the 13E isomer) on
rubber septa are suitable for monitoring moth populations during the entire flight season.
KEYWORDS: Browntail moth; Euproctis chrysorrhea; pheromone; synthesis; field trapping
INTRODUCTION
microsporidia (5), nucleopolyhedrosis viruses (7), and/or labor-
intensive nest removal (1). Efficient tools for monitoring
browntail moth populations and predicting potential outbreaks
would be a great aid in managing this pest.
The browntail moth, Euproctis chrysorrhea (Linnaeus) (Lepi-
doptera: Lymantriidae), is a pest of forest and orchard trees and
also a wide range of woody rosaceous plants and ornamental
shrubs (1, 2). It is primarily found in central and southern Europe
and North Africa (2). E. chrysorrhea was introduced into
Somerville, MA, in the late 19th century and became abundant
throughout eastern New England before declining after 1915
(3). Currently, the distribution of E. chrysorrhea in the United
States is limited to coastal dunes on Cape Cod, MA, and to
several coastal islands and neighboring coasts in Casco Bay,
ME (4). Eggs hatch in late summer, and the larvae build silken
webs in which they overwinter before emerging to feed in the
spring (1). At high population levels, E. chrysorrhea larvae may
completely defoliate hosts such as beach plum (Prunus mar-
itima) and black cherry (Prunus serotina) in Massachusetts.
Moreover, urticating hairs that are present on several life stages
can cause severe dermatitis in humans (5, 6), making E.
chrysorrhea a public health issue (1, 4, 5, 7). Efforts to control
E. chrysorrhea have included the use of insecticides (4, 8),
Surveys for E. chrysorrhea typically entail counting numbers
of nests of this web-making lymantriid; counts can then be used
in efforts to predict population levels the following year (4, 8, 9).
Light-trap catches have also been used to monitor population
dynamics and predict outbreaks of E. chrysorrhea (10). Because
these methods are labor-intensive and relatively inefficient, they
are generally regarded as inferior to monitoring with pheromone
traps. Leonhardt et al. (11) identified the main component of
the sex pheromone of E. chrysorrhea as (7Z,13Z,16Z,19Z)-
docosatetraenyl isobutyrate (1). The authors reported on the
availability of a synthetic pheromone that matched the natural
compound and attracted male moths in a short field trail as
efficiently as virgin females. However, the synthesis paper cited
in ref 11 as being in preparation did not follow, and to our
knowledge no further report on E. chrysorrhea pheromone has
appeared in the literature.
In 1995, the Beltsville Agricultural Research Center of the
USDA-ARS, received an inquiry from the Maine Forest Service
and the National Park Service, U.S. Department of Interior, on
the availability of a pheromone-based survey for the browntail
moth, populations of which had gone up by some accounts in
the Cape Cod and Casco Bay areas (4). We synthesized ester 1
and field-tested it in Cape Cod in 1995; we renewed our
synthetic and bioassay efforts in 2005, including different
* Author to whom correspondence should be addressed [e-mail
ashot.khrimiaa@ars.usda.gov; telephone (301) 504-6138; fax (301) 504-
6580].
† Invasive Insect Biocontrol and Behavior Laboratory, Beltsville
Agricultural Research Center.
§ CPHST Otis Laboratory.
‡ Beltsville Agricultural Research Center, retired.
10.1021/jf073161w This article not subject to U.S. Copyright. Published 2008 by the American Chemical Society
Published on Web 03/12/2008

Sec Pheromone of Browntail Moth
J. Agric. Food Chem., Vol. 56, No. 7, 2008 2453
(m,1H); 13C NMR δ 18.6, 18.7, 19.7, 25.0, 25.5, 25.8, 28.6, 28.9, 29.0.
29.6, 30.8, 32.3; 62.3, 62.8, 67.6, 79.9, 80.4, 98.8. Anal. Calcd for
C18H32O3: C, 72.91; H, 10.90. Found: C, 72.48; H, 10.84.
batches of pheromone in two types of formulations. In the
current paper, we present a full account of our synthesis and
field trapping studies.
(6Z)-13-(Tetrahydo-2H-pyran-2-yloxy)tridecen-1-ol (3). Alcohol
2 (15.68 g, 53 mmol) in hexanes (200 mL) was agitated in the presence
of Lindlar catalyst (1.57 g) in H2 atmosphere for ∼4 h or until GC
analysis showed no starting material present. The catalyst was removed
by filtration through Celite 521, and the filtrate was concentrated to
furnish 3 (15.37 g) of 94% purity. A part of this product (1.95 g) was
chromatographed on 20% AgNO3-SiO2 with hexanes/ethyl acetate,
1:1, to give alcohol 3 (1.16 g) of >99% purity: 1H NMR δ 1.00–1.90
(m, 20 H), 2.01 (m, H-5, H-8), 3.31–3.53 (m, 2H), 3.61 (t, H-1, J )
6.5 Hz), 3.66–3.90 (m, 2H), 4.56 (m, 1H), 5.33 (m, H-6, H-7); 13C
NMR δ 19.7, 25.4, 25.5, 26.1, 27.1 (two carbons), 29.1, 29.5, 29.6,
29.7, 30.8, 32.7; 62.3, 62.9, 67.6, 98.8, 129.6, 130.0. Anal. Calcd for
C18H34O3: C, 72.42; H, 11.50. Found: C, 72.11; H, 11.38.
(6Z)-13-(Tetrahydo-2H-pyran-2-yloxy)tridecenal (4). Alcohol 3
(1.75 g, 5.87 mmol) was oxidized with pyridinium chlorochromate
(PCC; 2.53 g, 11.72 mmol) in the presence of anhydrous sodium acetate
(1.59 g) in dry CH2Cl2 at 0-25 °C using a procedure of Corey and
Suggs (19). Conventional workup followed by subsequent flash
chromatography afforded aldehyde 4 (1.19 g, 68%): 1H NMR δ
1.00–1.90 (m, 18H), 2.05 (m, H-5, H-8), 2.40 (m, 2H), 3.40 (m, 1H),
3.52 (m, 1H), 3.73 (m, 1H), 3.87 (m, 1H), 4.60 (m, H-2′), 5.35 (m,
H-6, H-7), 9.78 (m, H-1). Anal. Calcd for C18H32O3: C, 72.91; H, 10.90.
Found: C, 72.64; H, 10.79.
(7Z,13Z,16Z,19Z)-Docosatetraenyl Isobutyrate (1). Sodium bis-
(trimethylsilyl)amide (4.1 mL, 1.0 M in THF, 4.1 mmol) was added
slowly under N2 atmosphere to a stirred suspension of 5b (2.45 g, 4.4
mmol) in dry THF (60 mL) at -70 °C. The mixture was stirred at
-75 °C for 3 h, and then a solution of aldehyde 4 (580 mg, 2.0 mmol)
in THF (3 mL) was introduced dropwise. The resulting mixture was
stirred at this temperature for 1 h, slowly warmed to 20 °C within 3 h,
and then quenched with a saturated NH4Cl solution. The mixture was
extracted with hexanes/ether, 3:1, and the combined organic extracts
were dried (Na2SO4), concentrated, and flash chromatographed with
hexanes/ethyl acetate, 25:1, to provide the Wittig condensation product
(680 mg). This was deprotected by refluxing for 4 h with pyridinium
tosylate (PPTS, 10 mg) in methanol (15 mL). After evaporation of
methanol, the resulting alcohol was taken into ether/hexanes, 1:1, and
the solution was washed with water, dried with Na2SO4, and concen-
trated. The crude alcohol was acylated with isobutyryl chloride (266
µL) and pyridine (210 µL) in dry toluene (15 mL) at 0-25 °C for 2 h.
Water was added, and the mixture was extracted with hexanes/ether,
1:1, and the organic extract was washed with 5% HCl and water and
then dried with Na2SO4. Evaporation of the solvent and flash chroma-
tography (hexanes/ethyl acetate, 40:1) provided ester 1 (625 mg, 81%):
1H NMR δ 0.97 (t, 3H, J ) 7.5 Hz), 1.15 (d, 6H, J ) 6.8 Hz), 1.35
(m, 10H), 1.62 (m, 2H, H-2), 1.90–2.20 (m, 8H), 2.53 (qq, J ) 6.8,
7.2 Hz, 1H), 2.80 (dd, J ∼ 5.7 Hz, H-15, H-18), 4.05 (t, J ) 6.9 Hz,
H-1), 5.36 (m, 8H); 13C NMR δ 14.25, 19.00 (two carbons), 20.54,
25.53, 25.63, 25.84, 27.11 (two carbons), 27.14, 28.63, 28.88, 29.27,
29.37, 29.60, 34.05, 64.35, 127.11, 127.77, 128.24, 128.30, 129.78,
129.84, 130.19, 131.96, 177.27; GC-MS (EI), m/z (%) 388 (M+, 2),
359 (1), 345 (2), 319 (3), 306 (2), 231 (2), 217 (6), 203 (6), 189 (4),
175 (5), 161 (10), 147 (14), 135 (22), 121 (32), 108 (46), 95 (67), 79
(100), 71 (40), 67 (91), 55 (56). Mass spectral data matched those of
the natural pheromone (11). Ester 1 was 92% pure by GC on HP-5
and SPB-1 columns. The main impurity (4%) that eluted after the
pheromone peak had a mass spectrum nearly identical to that of 1.
Two other impurities (total >3%) also had mass spectral profiles similar
to that of ester 1.
METHODS AND MATERIALS
Gas Chromatographic Analyses. We used a Shimadzu 17A gas
chromatograph (Columbia, MD) equipped with a 30 m HP-5 capillary
column (0.25 mm i.d., 0.25 µm film thickness; Agilent Technologies,
Santa Clara, CA), flame ionization detector, Shimadzu AOC-20s
autosampler, and AOC-20i autoinjector. Analyses were done in split
mode using hydrogen as a carrier gas at 1.0 mL/min. Analyses of
pheromone 1 were also conducted on an SPB-1 column (60 m × 0.25
mm × 0.25 µm film, Supelco, Bellefonte, PA).
Electron Impact (EI) Mass Spectra. EI-MS (70 eV) were obtained
with an Agilent Technologies 5973 mass selective detector interfaced
with an Agilent 6890N GC equipped with a 30 m × 0.25 mm i.d.,
0.25 µm film thickness, HP-5MS capillary column. Helium was used
as the carrier gas at 1.0 mL/min.
NMR Analyses. 1H NMR (300 MHz) and 13C NMR (75 MHz)
spectra were recorded in CDCl3 with TMS as an internal standard on
a Bruker QE-300 spectrometer.
Chemicals and Supplies. Unless otherwise specified, all reagents
were purchased from Aldrich Chemical Co., Milwaukee, WI. Flash
chromatography was carried out with 230–400 mesh silica gel (Fisher
Scientific, Fair Lawn, NJ). Lindlar catalyst, 5% Pd on CaCO3, lead
poisoned, was purchased from Strem Chemicals, Newburyport, MA.
Tetrahydrofuran (THF) was distilled from sodium benzophenone ketyl.
Methylene chloride and hexamethylphosphoramide (HMPA, highly
toxic!) were distilled from calcium hydride.
PreViously Described Intermediates: (3Z,6Z)-Nonadienyltriphe-
nylphosphonium bromide (5a) was prepared according to a procedure
of Wong et al. (12) with the following minor deviations. 3-Butyn-1-ol
was tetrahydropyranylated in the presence of pyridinium p-toluene-
sulfonate (13) instead of hydrochloric acid. The resulting product was
isolated by distillation (bp 50 °C/3 mmHg) in 75% yield. The tosylate
of 2-pentyn-1-ol was prepared using tosyl chloride and powdered KOH
in ether (14). The crude tosylate was used in the alkylation step without
further purification. Lindlar semihydrogenation of 3,6-nonadiyn-1-ol
was conducted in 94% yield in the presence of quinoline and
cyclohexene in methanol (15) instead of using quinoline in ethanol
(12). (3Z,6Z)-Nonadiene-1-ol of 95% purity was further purified by
argentation chromatography (16) using 15% AgNO3 on SiO2 (hexanes/
ethyl acetate/methanol, 5:1:1 to 5:3:1) to give a product of 99% purity.
Phosphonium salt 5a was prepared from (3Z,6Z)-1-bromononadiene
(1.0 equiv) and triphenylphosphine (1.2 equiv) by refluxing in aceto-
nitrile for 40 h. After evaporation of the solvent, the residue was washed
with anhydrous ether, and the oily salt 5a was used in the Wittig reaction
without further purification. (3Z,6Z)-Nonadienyltriphenylphosphonium
tosylate (5b) was prepared from (3Z,6Z)-nonadiene-1-ol by converting
it to the tosylate and reacting with triphenylphosphine in refluxed
acetonitrile for 13 h as described (17). After flash chromatography
(CH2Cl2/MeOH, 10:1), the viscous salt 5b was used in the olefination
step without crystallization. 6-Heptyn-1-ol was prepared from 3-heptyn-
1-ol (GFS Chemicals, Powell, OH) using a “zipper reaction” in the
presence of lithium salt of 1,3-diaminopropane and potassium tert-
butoxide (18). Tetrahydropyranyl protection of 6-bromo-1-hexanol was
achieved in the presence of pyridinium p-toluenesulfonate (13).
13-(Tetrahydo-2 H-pyran-2-yloxy)-6-tridecyn-1-ol (2). A solution
of methyl lithium in ether (0.176 mol; 110 mL of 1.6 M) was slowly
added under N2 atmosphere to a mechanically stirred solution of
6-heptyn-1-ol (9.88 g, 0.088 mol) in dry THF (90 mL) at ∼5 °C. The
suspension was stirred for about 20 min and cooled to -40 °C before
dry hexamethylphosphoramide (225 mL) was added. 2-(6-Bromohexy-
loxy)tetrahydro-2H-pyran (21.83 g, 0.082 mol) was added, and the
mixture was slowly warmed to ∼10 °C within 1.5 h. The mixture was
poured into ice–water and extracted with hexanes/ether (1:1), and the
combined organic extract was washed with a solution of NH4Cl and
dried with Na2SO4. Evaporation of the solvent and subsequent distil-
The reaction was also conducted with 4.0 mmol of aldehyde 4 and
10.0 mmol of salt 5a with other components increased proportionally.
The yield of olefination was 90%, and the GC purity of ester 1 was
88%. The amount of the main impurity that eluted after the pheromone
peak was 7%; two other impurities having mass spectra similar to that
of ester 1 amounted to ∼2%, and unidentified byproducts totaled 3%.
A part of this material (200 mg) was further purified by flash
1
lation afforded 2 (16.18 g, 67%): bp 170 °C/0.04 mmHg; H NMR δ
1.00–1.90 (m, 20 H), 2.13 (m, H-5, H-8), 3.31–3.90 (m, 6H), 4.56

2454 J. Agric. Food Chem., Vol. 56, No. 7, 2008
Khrimian et al.
Scheme 1. Synthesis of (7Z,13Z,16Z,19Z)-Docosatetraenyl Isobutyrate
Sex Pheromone of Browntail Moth, Euproctis chrysorrhea (L.)a
Figure 1. Residual amounts of browntail moth pheromone 1 (93% isomeric
purity) on rubber septa exposed to field conditions (initial loading, 250
µg/lure; three replicates).
a Reagent and conditions: (a) 2Meli/ether-THF; (b) Br(CH2)6OTHP/HMPA;
(c) H2/Pd-CaCO3; (d) AgNO3-SiO2; (e) PCC/AcONa; (f) 1, [(CH3)3Si]2NNa/
THF, -70 °C; 2, 4, -75 °C; (g) 1, PPTS/MeOH; 2, (CH3)2CHCOCI/py.
chromatography on 15% AgNO3-SiO2 with hexanes/ethyl acetate, 10:1
to 1:2, to provide pheromone 1 (102 mg) of 94% chemical and isomeric
purities.
We purified the intermediates in early stages of the synthesis
by argentation chromatography (16) to ensure 99% geometric
purity of both olefination components. Sodium bis(trimethyl-
silyl)amide (22) was used as a base to give 90% yield of the
Wittig olefination from bromide 5a. On the basis of GC and
GC-MS data, as well as the literature on the stereoselectivity
of the Witting reaction (22), we concluded that the main
impurity (7%) that eluted after the pheromone peak on both
GC columns was the 13E isomer of 1. Two additional impurities
(total 2%) with comparable retention times and mass spectra
were apparently other isomers of 1. Thus, the chemical purity
of the pheromone was 88% and the isomeric purity 91%. This
product was further purified by argentation chromatography to
furnish a pheromone of 94% chemical and isomeric purities
(containing 4% of 13E isomer). From the tosylate 5b we
obtained the final product of 92% chemical and 93% isomeric
purity in 81% yield. Thus, both bromide 5a and tosylate 5b
offer high yields and comparable stereochemical outcomes in
the olefination step. However, the tosylate route may seem
advantageous because the starting salt is easier to prepare (13
vs 40 h of reaction time in the case of bromide).
Field Bioassay. In both years’ field trials, numbers of male
E. chrysorrhea captured in sticky traps increased with increasing
doses of pheromone 1 on the lures. In 1995, the 25 µg/septum
dosage captured significantly fewer moths than did any of the
higher dosages, and traps baited with 50 µg septa caught
significantly fewer than those baited with 250 µg. Capture with
100 µg septa was intermediate to, but not significantly different
from, capture with 50 and 250 µg septa. Leonhardt et al. (11)
reported that traps baited with 5–50 µg of the synthetic
pheromone 1 dispensed from rubber septa gave male moth
captures that were comparable to those of traps baited with three
virgin females. However, their 250 µg/septum dose was not
significantly different from a 25 µg dose in the same field trial
(11). We measured the release rate of the pheromone from 250
µg dispensers under field conditions (Figure 1) and found a
good linear regression with an average release of ∼2.4 µg/day
that represents both emitted pheromone and possible decom-
position products. About 59% of material remained after 43 days
of exposure, thus indicating that this loading may persist during
entire E. chrysorrhea flight season, which lasts several weeks.
Pheromone Dispensers and Release Rates. Hexane solutions of 1
(10 mg/mL) containing 1.0% butylated hydroxytoluene (BHT) and 1.0%
Tinuvin 328 UV light absorber (Ciba Specialty Chemicals, Basel,
Switzerland) were applied via a syringe into caps of gray (halobutyl)
rubber septa (The West Company, Kearney, NE) washed with acetone/
hexane, 1:1, in a Soxhlet extractor prior to use. Poly(vinyl chloride)
(PVC)-coated string dispensers were prepared from 94% pheromone
batch stabilized with 1.0% BHT and 1.0% Tinuvin 328 as described
by Leonhardt et al. (20). The loading of the pheromone was 73 µg/cm.
During the 1995 field test, the release of the pheromone from rubber
septa was measured by residual analyses of dispensers (250 µg, 93%
isomerically pure) that were aged outdoors in Pherocon 1C traps (Trécé
Inc., Adair, OK) at the Otis laboratory on Cape Cod. After aging for
a specified time (Figure 1) three septa per age were individually
Soxhlet-extracted with 15 mL of hexane, and the solutions were
quantitatively analyzed by GC in a splitless mode using external
standards. Aging of septa was concurrent with the field bioassay.
Field Bioassay. In 1995, we tested pheromone of 93% isomeric
purity on rubber septa in four doses, 25, 50, 100, and 250 µg/septum.
The test was conducted in the Pilgrim Heights area of Truro, MA, within
the boundaries of the Cape Cod National Seashore, from July 17 to
August 1. Pherocon 1C sticky traps were assembled with spacer tubes
(provided) in place, resulting in a 1.5-2 cm gap between the top and
bottom sections of the trap. Septa were attached to the underside of
the top of the trap. Traps were hung from metal stakes at ∼1 m above
the ground with a minimum intertrap spacing of 40 m. The test design
was a randomized complete block with five replicates. Captured moths
were counted 10 times (every 1–2 days) during the test; at each check,
positions of bait treatments within each block were rerandomized.
In 2005, the field test was again conducted in Pilgrim Heights using
methods similar to those described above. Traps were checked and
rerandomized within each of the five blocks six times (every 2–3 days)
from July 15 to July 29. Lures included rubber septa and string
formulations loaded with pheromone 1 from a batch of 94% isomeric
purity. Treatments on rubber septa contained 0, 25, 100, 250, and 1000
µg/lure; those on string dispensers contained 250 and 1000 µg/lure.
Septa and string lures containing 1000 µg were also aged outdoors in
white cardboard delta traps for 2 or 4 weeks immediately prior to the
field trial. In addition, we tested rubber septa that contained 250 and
1000 µg of pheromone 1 from a second batch of 91% isomeric purity.
RESULTS AND DISCUSSION
Synthesis. The key step in the assembly of a skipped triene
moiety of the pheromone 1 (Scheme 1) was the Wittig
olefination of the unsaturated aldehyde 4 with a phosphorane
generated from the salt 5. Both bromide 5a (12) and tosylate
5b (17) have previously been described and used in similar
olefinations. The unsaturated aldehyde 4 was prepared using a
conventional acetylenic chemistry, particularly employing an
efficient alkylation of lithium acetylides in THF/HMPA (21).
In 2005, in addition to rubber septa, we incorporated in our
field test string formulations that were successfully used in field
trapping of the gypsy moth, Lymantria dispar (20), and the pink
gypsy moth, Lymantria mathura (15). We also conducted a
dose–response experiment, as well as an aging test and a
pheromone purity trial. The results of the dose–response field
test presented in Table 2 were consistent with those obtained

Sec Pheromone of Browntail Moth
J. Agric. Food Chem., Vol. 56, No. 7, 2008 2455
Table 1. Capture of Male Browntail Moths in Traps Baited with Different
Amounts of (7Z,13Z,16Z,19Z)-Docosatetraenyl Isobutyrate (1, 93%
Isomeric Purity) on Rubber Septa (Cape Cod National Seashore, from July
17 to August 1, 1995)
Table 4. Capture of Male Browntail Moths in Traps Baited with 250 or
1000 µg of (7Z,13Z,16Z,19Z)-Docosatetraenyl Isobutyrate (1, 94% Isomeric
Purity) on Rubber Septa or PVC-Plasticized String Formulations, Aged 0,
2, or 4 Weeks (Pilgrim Heights Area of Truro, MA, Cape Cod National
Seashore Park, July 2005)
total male moths per trapa (x¯ ( SE)
attractant per septum (µg)
male moths per trap
per week (x¯ ( SE)a
25
50
100
250
83 ( 10 a
127 ( 21 b
164 ( 35 bc
200 ( 37 c
dispenser loading (µg) age (weeks)
week 1
week 2
septum
250
1000
1000
1000
0
0
2
4
19.4 ( 3.6 b
29.2 ( 7.0 b
27.0 ( 5.1 b
24.0 ( 3.4 b
40.2 ( 3.7 cd
43.2 ( 6.5 cd
60.4 ( 8.2 d
49.0 ( 8.5 d
a Means followed by the same letter are not significantly different as determined
by Tukey’s HSD test (R ) 0.05). Traps were checked daily, but data for each of
six traps per treatment were summed across days and transformed to ln(n + 1)
prior to ANOVA (F ) 15.9; df ) 3, 15; P < 0.0001).
string
250
1000
1000
1000
0
0
2
4
19.0 ( 3.6 b
18.6 ( 3.6 b
13.2 ( 2.5 b
1.2 ( 0.6 a
11.2 ( 7.5 b
14.8 ( 5.1 bc
0.4 ( 0.2 a
0.0 ( 0.0 a
Table 2. Capture of Male Browntail Moths in Traps Baited with Different
Amounts of (7Z,13Z,16Z,19Z)-Docosatetraenyl Isobutyrate (1, 94%
Isomeric Purity) on Rubber Septa (Pilgrim Heights Area of Truro, MA,
Cape Cod National Seashore Park, July 2005)
a Within a column, means that are not followed by the same letter are significantly
different as determined by Tukey’s HSD test (R ) 0.05). Data for each trap were
summed within each of 2 weeks and transformed to ln(n + 1) prior to ANOVA. In
initial analyses, there was a significant interaction between week and treatment (F
) 9.56; df ) 7, 28; P < 0.0001), so data for each week were analyzed individually.
The treatment effect (incorporating dispenser, loading, and aging) was highly
significant for both week 1 (F ) 13.45; df ) 7, 28; P < 0.0001) and week 2 (F )
32.5; df ) 7, 28; P < 0.0001).
male moths per trap per weeka (x¯ ( SE)
attractant per septum (µg)
0
25
100
250
1000
0.4 ( 0.2
7.1 ( 1.4 a
16.7 ( 2.4 b
29.8 ( 4.2 bc
36.2 ( 5.1 c
a Means that are not followed by the same letter are significantly different as
determined by Tukey’s HSD test (R ) 0.05). Data for each trap were summed
within each of 2 weeks and transformed to ln(n + 1) prior to ANOVA (F ) 13.96;
df ) 3, 31; P < 0.0001; 4 treatments, 5 blocks, 2 weeks). Data for 0 µg lures
were not included in the analysis. Interactions between main effects were not
significant and were not included in the final model.
after 4 weeks of aging (Table 4, last row), and the string
dispenser with the same loading aged for 2 weeks retained the
attractiveness only in the week 1 test but was entirely inactive
in week 2. Similarly, a fresh 250 µg string dispenser was as
active as rubber septa formulations in week 1 but caught a
significantly fewer number of moths in week 2. We did not
measure release rates in 2005, but it seems that the string
dispensers (unlike rubber septa) became depleted of pheromone
lure in 2-3 weeks under field condition.
In summary, we presented the first synthesis of the sex
pheromone of the browntail moth, E. chrysorrhea, (7Z,13Z,-
16Z,19Z)-docosatetraenyl isobutyrate. Rubber septa formulations
of the pheromone of 91–94% isomeric purity (presumably
containing 4–7% of the 13E isomer) can be efficiently used for
monitoring the moth populations during the entire flight season.
Table 3. Capture of Male Browntail Moths in Traps Baited with
(7Z,13Z,16Z,19Z)-Docosatetraenyl Isobutyrate of 91 and 94% Isomeric
Purities on Rubber Septa (Pilgrim Heights Area of Truro, MA, Cape Cod
National Seashore Park, July 2005)
male moths per trap
per weeka (x¯ ( SE)
attractant per
isomeric
septum (µg)
purity (%)
250
1000
250
94
94
91
91
29.8 ( 4.2
36.2 ( 5.1
25.6 ( 4.5
41.9 ( 7.0
1000
ACKNOWLEDGMENT
a Data for each trap were summed within each of 2 weeks and transformed to
ln(n + 1) prior to ANOVA. Dose and purity were treated as separate effects (2
levels each; 5 blocks, 2 weeks). Dose–effects were significant (F ) 4.57; df ) 1,
32; P ) 0.040); purity was not (F ) 0.002; df ) 1, 32; P ) 0.97). Interactions
between main effects were not significant and were not included in the final model.
The assistance of N. H. Dees and F. Guzman, USDA-ARS,
Beltsville, in syntheses and analyses is much appreciated. M.
Morse and S. Gutowski, USDA-APHIS, Otis ANGB, MA,
provided excellent support for the field trials.
in the 1995 (Table 1). The 100 and 250 µg treatments were
significantly better than a 25 µg dose but not significantly
different from each other. The highest dose, 1000 µg/lure, did
not capture significantly higher numbers of male E. chrysorrhea
than the 250 µg treatment. At any rate, the 250 µg/septum dose
was both efficient and economical from the two field trials. The
performances of traps baited with pheromones of 91 and 94%
isomeric purities at two doses were not significantly different
(Table 3) thus rendering unnecessary a costly argentation
chromatography in the last step.
LITERATURE CITED
(1) Pest Alert. Browntail Moth, NA-PR-04-02; U.S. Department of
Agriculture, Forest Service, Northeastern Area, 2004.
(2) Carter, D. J. Pest Lepidoptera of Europe: with Special References
to British Isles; Dr. W. Junk Publishers: Dordrecht, Germany,
1984; pp 245–248.
(3) Burgess, A. F.; Baker, W. L. The Gypsy Moth and Brown-Tail
Moths and Their Control; Bulletin 464; U.S. Department of
Agriculture: Washington, DC, 1938.
(4) Bradbury, R. L. The Browntail Moth, Euproctis chrysorrhoea;
summary of Maine Forest Service activities for 1995; Technical
Report 38; Maine Forest Service, Maine Department of Conserva-
tion, Insect and Disease Management Division: Augusta, ME,
1998.
(5) Sterling, P. H.; Speight, M. R. Comparative mortalities of the
brown-tail moth, Euproctis chrysorrhoea (Lepidoptera: Lyman-
triidae) in southeast England. Bot. J. Linn. Soc. 1989, 101, 69–
78.
The results of aging and dispenser type studies are presented
in Table 4. It is noteworthy that all four treatments on rubber
septa in both week 1 and week 2 trappings were not significantly
different from each other. Thus, aging of the 1000 µg lure for
4 weeks under field conditions before the trial did not affect
the lure attractiveness. In contrast, a string dispenser with the
1000 µg pheromone loading completely lost its attractiveness

2456 J. Agric. Food Chem., Vol. 56, No. 7, 2008
Khrimian et al.
(6) De Jong, M. C. J. M.; Bleumink, E.; Nater, J. P. Investigative
studies of the dermatitis caused by the larva of the brown-tail
moth (Euproctis chrysorrhoea Linn.) I. Clinical and experimental
findings. Arch. Dermatol. Res. 1975, 253, 287–300.
(7) Cory, J. S.; Hirst, M. L.; Sterling, P. H.; Speight, M. R. Narrow host
range nucleopolyhedrovirus for control of the browntail moth
(Lepidoptera: Lymantriidae). EnViron. Entomol. 2000, 29, 661–
667.
(8) Bradbury, R. L. The Browntail Moth, Euproctis chrysorrhoea;
summary of Maine Forest Service activities for 1996; Technical
Report 40; Maine Forest Service, Maine Department of Conservation,
Insect and Disease Management Division: Augusta, ME, 1999.
(9) Arevalo-Durup, P. The winter nest of the brown-tail moth, Euproctis
chrysorrhoea (L). (Lepidoptera: Lymantriidae): description and
internal structure. Ann. Soc. Entomol. Fr. 1993, 29, 47–54.
(10) Meineke, T. Fluctuation curves of some moth species (Lepi-
doptera) from wooded and open habitats in southern Lower
Saxony. Verh. Ges. Oekol. 1987, 17, 799–804.
(11) Leonhardt, B. A.; Mastro, V. C.; Schwarz, M.; Tang, J. D.;
Charlton, R. E.; Pellegrini-Toole, A.; Warthem, J. D.; Schwalbe,
C. P.; Carde, R. T. Identification of sex pheromone of browntail
moth Euproctis chrysorrhoea (L.) (Lepidoptera: Lymantriidae).
J. Chem. Ecol. 1991, 17, 897–910.
(15) Khrimian, A.; Oliver, J. E.; Hahn, R. C.; Dees, N. H.; White, J.;
Mastro, V. C. Improved synthesis and deployment of (2S,3R)-2-
(2Z,5Z-octadienyl)-3-nonyloxirane, a pheromone of the pink moth,
Lymantri mathura. J. Agric. Food Chem. 2004, 52, 2890–2895.
(16) Millar, J. G. Liquid chromatography. In Methods in Chemical
Ecology; Millar, J. G., Haynes, K. F., Eds.; Kluwer Academic
Publishers: Norwell, MA 1998; Vol. 1, pp 38–84.
(17) Taber, D. F.; You, K. New synthon for the convergent construction
of skipped conjugation polyenes: synthesis of ethyl docosa-
4,7,10,13,16,19-hexaenoate. J. Org. Chem. 1995, 60, 139–142.
(18) Abrams, S. R.; Shaw, A. C. Triple bond isomerization: 2- to
9-decyn-1-ol. Org. Synth. 1987, 66, 127–130.
(19) Corey, E. J.; Suggs, J. W. Pyridinium chlorochromate. An efficient
reagent for oxidation of primary and secondary alcohols to
carbonyl compounds. Tetrahedron Lett. 1975, 16, 2647–2650.
(20) Leonhardt, B. A.; Mastro, V. C.; DeVilbiss, E. D. New dispenser
for the pheromone of the gypsy moth (Lepidoptera: Lymantriidae).
Forest Entomol. 1993, 86, 821–827.
(21) Schwarz, M.; Waters, R. M. Insect sex attractants; XII. An efficient
procedure for the preparation of unsaturated alcohols and acetates.
Synthesis 1972, 567–568.
(22) Bestmann, H. J.; Stransky, W.; Vostrowsky, O. Reactions of
alkylidentriphenylphosphoranes. XXXIII. Preparations of lithi-
umsaltfree ylidsolutions with sodium bis(trimethylsilyl)amide as
base. Chem. Ber. 1976, 109, 1694–1700.
(12) Wong, J. W.; Palaniswamy, P.; Underhill, E. W.; Steck, W. F.;
Chisholm, M. D. Sex pheromone components of fall cankerworm
moth, Alsophila pometaria. Synthesis and field trapping. J. Chem.
Ecol. 1984, 10, 1579–1596.
(13) Miyashita, M.; Yoshikoshi, A.; Grieco, P. A. Pyridinium p-
toluenesulfonate. A mild and efficient catalyst for the tetrahydro-
pyranylation of alcohols. J. Org. Chem. 1977, 42, 3772–3774.
(14) Brandsma, L.; Verkruijsse, H. D. Synthesis of Acetylenes, Allenes
and Cumulenes; Elsevier Scientific Publishing: Amsterdam, The
Netherlands, 1981; pp 223–224.
Received for review October 29, 2007. Revised manuscript received
February 1, 2008. Accepted February 4, 2008. Mention of a proprietary
company or commercial products does not constitute an endorsement
by the USDA.
JF073161W