Insecticidal activity of menthol derivatives against mosquitoes

Article abstract of DOI:10.1002/ps.1516

BACKGROUND: The insecticidal activity of essential oil of Mentha piperita L. emend. Huds. against local mosquitoes as disease vectors was recognized and found to be due to the presence of menthol, which is the major aroma compound of the oil. The minor compounds of the oil, i.e. menthone, β-caryophyllene, menthyl acetate, limonene, α-pinene and pulegone, showed either less or no activity against the mosquitoes tested. L-Menthol derivatives were synthesized and their knockdown effect and mortality were evaluated against local mosquitoes of Culex quinquefasciatus Say, Aedes aegypti L. and Anopheles tessellatus Theobald as disease vectors. This is the first report of mosquitocidal activity of menthol and its derivatives against Cx. quinquefasciatus, Ae. aegypti and An. tessellatus. RESULTS: Derivative synthesis followed by structure-activity relationship studies identified several derivatives, i.e. menthyl chloroacetate, menthyl dichloroacetate, menthyl cinnamate, menthone glyceryl acetal, thymol, α-terpineol and mugetanol, with enhanced mosquitocidal activity against Cx. quinquefasciatus, Ae. aegypti and An. tessellatus relative to the parent compound L-menthone. CONCLUSION: In ester derivatives of L-menthol the optimum activity is dependent on the size and shape of the ester group and the presence of chlorine atoms in the ester group. In structurally related derivatives of L-menthol the optimum activity is dependent on the aromaticity, the degree of unsaturation, the position of the hydroxy group and the type of functional group.

Full text of DOI:10.1002/ps.1516

Pest Management Science
Pest Manag Sci 64:290–295 (2008)
Insecticidal activity of
menthol derivatives against mosquitoes†
Radhika Samarasekera,1∗ Indira S Weerasinghe2 and KD Patrick Hemalal3
1Natural Products Development Group, Industrial Technology Institute (Successor to CISIR), 363, Bauddhaloka Mawatha, Colombo 7,
Sri Lanka
2Department of Entomology, Medical Research Institute, Colombo 8, Sri Lanka
3Applied Research and Development Centre, Hemas Manufacturing (Pte) Ltd, Negombo Road, Welisara, Sri Lanka
Abstract
BACKGROUND: The insecticidal activity of essential oil of Mentha piperita L. emend. Huds. against local
mosquitoes as disease vectors was recognized and found to be due to the presence of menthol, which is the major
aroma compound of the oil. The minor compounds of the oil, i.e. menthone, β-caryophyllene, menthyl acetate,
limonene, α-pinene and pulegone, showed either less or no activity against the mosquitoes tested. L-Menthol
derivatives were synthesized and their knockdown effect and mortality were evaluated against local mosquitoes of
Culex quinquefasciatus Say, Aedes aegypti L. and Anopheles tessellatus Theobald as disease vectors. This is the
first report of mosquitocidal activity of menthol and its derivatives against Cx. quinquefasciatus, Ae. aegypti and
An. tessellatus.
RESULTS: Derivative synthesis followed by structure–activity relationship studies identified several derivatives,
i.e. menthyl chloroacetate, menthyl dichloroacetate, menthyl cinnamate, menthone glyceryl acetal, thymol, α-
terpineol and mugetanol, with enhanced mosquitocidal activity against Cx. quinquefasciatus, Ae. aegypti and An.
tessellatus relative to the parent compound L-menthone.
CONCLUSION: In ester derivatives of L-menthol the optimum activity is dependent on the size and shape of the
ester group and the presence of chlorine atoms in the ester group. In structurally related derivatives of L-menthol
the optimum activity is dependent on the aromaticity, the degree of unsaturation, the position of the hydroxy
group and the type of functional group.
 2007 Society of Chemical Industry
Keywords: menthol; insecticidal activity; mosquitoes; Culex quinquefasciatus; Aedes aegypti; Anopheles tessellatus;
structure-activity relationships
been considered as potent alternatives to conventional
insecticides as a natural means of pest control.3,4
Insect control properties of plant essential oils and
their constituents and derivatives have been described
previously.5–10 However, there have been no previous
publications on the mosquitocidal activity of menthol
and its derivatives.
In search of insecticidal properties of plant essential
oils, the insecticidal activity of Mentha piperita L.
emend. Huds. oil was recognized against local
mosquito disease vectors and shown to be due to
the presence of menthol, which is the major aroma
compound of the oil. Previous publications on the
insecticidal activity of menthol and menthol derivatives
cover only the compounds menthyl acetate and
pivalate, which were described as insecticidal against
Musca domestica L.5,11 The other reported biological
activities of menthol and its derivatives include
1
INTRODUCTION
Public health pest control is a major priority to min-
imize infection by and transmission of vector-borne
diseases in tropical regions. Diseases transmitted by
mosquitoes, such as malaria, lymphatic filariasis and
numerous viral diseases such as dengue, dengue haem-
orrhagic fever, Japanese encephalitis and yellow fever,
affect billions of people worldwide including Sri Lanka
each year. The development of resistance by vector
mosquitoes in Sri Lanka1,2 is reducing the effective-
ness of synthetic insecticides such as pyrethroids in
mosquito control. Also, many of the synthetic insec-
ticides, especially chlorinated hydrocarbons, are toxic
to humans and have detrimental environment effects.
The adverse effects of synthetic insecticides have
necessitated the search for more acceptable plant-
based products for mosquito control. In recent years,
plant essential oils and essential oil constituents have
∗ Correspondence to: Radhika Samarasekera, Natural Products Development Group, Industrial Technology Institute (Successor to CISIR), 363, Bauddhaloka
Mawatha, Colombo 7, Sri Lanka
E-mail: radhika@iti.lk
†Part of this study was presented at the Annual Sessions of the Institute of Chemistry, Sri Lanka, 19–21 June 2002
(Received 8 December 2005; revised version received 29 September 2006; accepted 8 December 2006)
Published online 20 December 2007; DOI: 10.1002/ps.1516
 2007 Society of Chemical Industry. Pest Manag Sci 1526–498X/2007/$30.00

Activity of menthol derivatives against mosquitoes
2.2 Derivative synthesis
antimicrobial,12,13 anti-inflammatory,13 analgesic13,14
and central nervous system excitation effects,13 and
insecticidal activity against stored-product pests.15
Menthol and menthol derivatives are commonly used
as cooling agents in cosmetic products and also as
flavouring for toothpaste, other oral hygiene products
and chewing gum.14
In the present study, M. piperita oil, its major aroma
compound, menthol, and synthesized menthol deriva-
tives were investigated for mosquitocidal activity, and
the activity of menthol derivatives was compared with
that of L-menthol in order to evaluate the effect of
derivatization and to establish structure–activity rela-
tionships (SARs) of the compounds with the aim of
identifying structural features that are necessary for
mosquitocidal activity.
Acyl and aryl derivatives of L-menthol, i.e. menthyl
acetate, chloroacetate, dichloroacetate, trifluroacetate,
propionate, chloropropionate, pivalate and benzoate,
were synthesized by reaction with acid anhydrides
or acid halides in the presence of a catalytic quan-
tity of pyridine or triethylamine in dichloromethane
at room temperature.7,16–18 Acyl derivatives of L-
menthol with an acid moiety (lactic acid or cinnamic
acid), i.e. menthyl lactate and cinnamate, were syn-
thesized by reaction with dicyclohexylcarbodiimide
and 4-dimethylaminopyridine as condenser and cata-
lyst in dichloromethane at room temperature.7 The
methoxy derivative of L-menthol, menthyl methyl
ether, was synthesized by reaction with dimethyl sul-
fate and anhydrous potassium carbonate under reflux
in dry acetone.19 The glyceryl acetal derivative ofL-
menthol was synthesized by reaction with glycerol and
p-toluenesulfonic acid under reflux in toluene.20 Reac-
tions were monitored by thin-layer chromatography,
using a mixture of hexane and ethyl acetate, and com-
pounds were visualized by vanillin-sulfuric acid spray,
heat and under UV light. Compounds were purified
by dry-column flash chromatography,21 eluting with
hexane + ethyl acetate.
2
EXPERIMENTAL METHODS
2.1 Essential oil, compounds and chemicals
used
The compounds tested are shown in Figs 1 and 2.
Mentha piperita (mint) oil was purchased from
Hendrikson & Sons Pvt Ltd., Colombo, Sri Lanka. L-
Menthol, L-menthone, thymol, α-terpineol, pulegone
and mugetanol were purchased from Haarmann &
Reimer GmbH, Holzminden, Germany. Chemicals
and reagents used for derivative synthesis were
purchased from Fluka Chemie GmbH, Buchs,
Switzerland, and VWR International Ltd, Poole, UK,
and were analytical grade.
2.3 Gas chromatography (GC) analysis
Constitutional analysis of M. piperita oil was carried
out on a gas–liquid chromatograph (Shimadzu
GC-2010, Shimadzu, Japan) equipped with flame
CH3
CH3
CH3
O
OH
OR
CH3
R
O
H3C
CH3
CH3
H3C
H3C
MENTHYL
1
MENTHONE
2
MENTHONE GLYCERYL ACETAL
2b
OH
H3C
CH3
CH3
OH
CH3
THYMOL
OH
CH3
H3C
H3C
H3C
CH3
α-TERPINEOL
MUGETANOL
5
3
4
CH3
O
H3C
CH3
PULEGONE
6
Figure 1. Structures of compounds discussed (for R, see Fig. 2).
Pest Manag Sci 64:290–295 (2008)
291
DOI: 10.1002/ps

R Samarasekera, IS Weerasinghe, KDP Hemalal
2.5 Insecticidal assay
2.5.1 Mosquitocidal bioassay
DERIVATIVEa
Menthol (parent)
Rb
Menthol compounds and M. piperita essential oil were
tested for knockdown effect and mortality against
three-day-old adult females of Culex quinquefascia-
tus Say, Aedes aegypti L. and Anopheles tessellatus
Theobald. The mosquitoes tested are all Sri Lankan
strains and have been colonized in the insectary for
10 years at the Medical Research Institute, Sri Lanka.
Mosquitoes were reared under laboratory conditions
in the insectary at 27 ◦C and 80% relative humidity
and under a 14:10 h light:dark photoperiod.
H
1a
O
1b
1c
1d
1e
1f
Acetate
CH3
C
O
Chloroacetate
Dichloroacetate
Trifluoroacetate
Propionate
C
O
CH2Cl
CHCl2
CF3
C
O
C
O
C
The bioassay was conducted in an experimental
kit consisting of two cylindrical plastic tubes both
measuring 125 × 44 mm following the WHO standard
method for adult mosquito susceptibility testing24
using papers impregnated with 1.5 mL of 20,
10, 5, 2.5 or 1.25 g L−1 ethanol solutions of the
compounds/essential oil. One tube served to expose
the mosquitoes to the compounds/essential oil, and
another tube was used to hold the mosquitoes before
and after the exposure periods. The impregnated
papers were rolled and placed in the exposure tube.
Fifteen glucose-fed adult female mosquitoes were
exposed to the impregnated papers, and the number
of mosquitoes knocked down after a 1 h exposure
period was recorded. Mosquitoes were transferred to
a holding tube and kept for 24 h under laboratory
conditions. A cotton pad soaked in 20% glucose
solution was placed in the tube during the holding
period of 24 h. Mortality of the mosquitoes was
recorded after 24 h, and results were expressed in terms
of mass of test compound per unit volume of the test
apparatus (µg mL−1). An ethanol control was carried
out simultaneously with the test, and knockdown and
mortality were zero. Each test was carried out in
triplicate.
CH2CH3
O
C
1g
1h
1i
Chloropropionate
Pivalate
CH2CH2Cl
C(CH3)3
O
C
Benzoate
B z
O
C
1j
Lactate
CH(OH)CH3
CH=CH Ph
O
C
1k
1l
Cinnamate
CH3
Methyl ether
Menthone (parent)
Glyceryl acetal
O
2a
2b
O
CH
CH2OH
CH2
O
Figure 2. Menthol and menthone derivatives synthesized
(acompound identification name and number in Table 1; bR in Fig. 1).
ionization detection. An SGE BP-20 capillary column
30 m × 0.25 mm, film thickness 0.25 µm, was used.
Oven temperature was programmed from 60 to 225 ◦C
at 5 ◦C min−1. Injector and detector temperatures were
kept at 230 and 240 ◦C respectively. Argon was used
2.5.2 Data analysis
KD50 and LC50 values and 95% fiducial limits were
calculated from the values obtained for knockdown
and mortality with 20, 10, 5, 3, 2.5 and 1.25 g L−1
solutions of the compounds/essential oil. Data were
analysed by probit analysis using an SPSS statistical
package.25,26
as the carrier gas at a flowrate of 1.00 mL min−1
.
The compounds of M. piperita oil were identified
by comparing the GC retention times with those
of authentic standard compounds and by the peak
enrichment technique.
3
RESULTS AND DISCUSSION
Although the insecticidal properties of certain essential
oils, their constituents and derivatives have been well
established,4–8,11,15,16,27 studies on the activity of these
against adult mosquitoes have not been previously
reported except in the authors’ ongoing work.9,10,28 In
preliminary studies, M. piperita essential oil showed
good mosquitocidal activity, and hence the oil was
analysed for its chemical composition by GC and
the insecticidal activity of the major components
was tested against local disease vector mosquitoes.
GC analysis of the leaf oil of M. piperita showed
that menthol (41.2%) was the major constituent and
2.4 Spectroscopy
The chemical structures of the menthol com-
pounds synthesized, menthyl acetate, chloroacetate,
dichloroacetate, trifluoroacetate, propionate, chloro-
propionate, pivalate, benzoate, lactate and cinnamate,
menthyl methyl ether and a racemic mixture of men-
thone glyceryl acetal, were confirmed by H and 13C
1
NMR spectral data.22,23 1H and 13C NMR were
recorded on Varian Magnetic 300 MHz and Varian
Gemini 200 MHz spectrometers (Varian, Inc., USA)
using deuterochloroform as solvent.
292
Pest Manag Sci 64:290–295 (2008)
DOI: 10.1002/ps

Activity of menthol derivatives against mosquitoes
menthone (24.3%), β-caryophyllene (5.1%), menthyl
acetate (2.0%), limonene (1.1%) and α-pinene (1.1%)
were the other constituents present in >1% of the oil.
It was found that pulegone was present in the oil in
0.07%.
these derivatives, menthyl chloroacetate, chloropro-
pionate, dichloroacetate, carboxamide and menthone
glyceryl acetal showed more mosquitocidal activity
than menthol, menthone and menthyl methyl ether,
indicating that the presence of ester groups, which
make the molecule more lipophilic, enhances the
mosquitocidal activity more than the hydroxyl, ether
and carbonyl functionalities. The conversion of the
carbonyl group in L-menthone by derivatization to
an acetal group in menthone glyceryl acetal signif-
icantly enhanced the insecticidal activity, indicating
that the presence of two oxygen atoms in a hemi-
acetal ring makes a significant contribution towards
enhancing the activity. It was also observed that an
alcohol, L-menthol, was more effective than the ana-
logues ketone and L-menthone in the mosquitocidal
bioassays.
It also appeared that derivatization of L-menthol
with less bulky groups such as acetate tends to
decrease the mosquitocidal activity below that of
more bulky acyl and aryl groups, and this was
supported by the derivatives, menthyl acetate and
methyl ether, which showed either weak or no
mosquitocidal activity, and by menthone glyceryl
acetal, which showed more mosquitocidal activity.
Among the ester derivatives, menthyl choroacetate,
dichloroacetate and chloropropionate showed greater
activity against the mosquitoes tested than acetates
and propionates owing to the presence of the
chlorine atom in the ester group. The trifluoroacetate
derivative showed either weak or no activity against
the tested mosquitoes at 20 g L−1, indicating that
the presence of more than one halogen atom
tends to decrease activity. The presence of a
nitrogen atom in the esterifying group retained the
mosquitocidal activity against An. tessellatus and Ae.
aegypti.
Structurally related analogues of menthol, i.e. thy-
mol, α-terpineol, pulegone and mugetanol (Figs 1
and 2), have either comparable mosquitocidal activ-
ity with menthol or more mosquitocidal activity
(Table 1), indicating that structural variations in the
molecule could contribute either towards retaining
or towards enhancing the activity. Thymol showed
higher activity against An. tessellatus and Ae. aegypti
than L-menthol, indicating that aromaticity is also a
key factor in enhancing the activity of menthol. α-
Terpineol showed more mosquitocidal activity against
Ae. aegypti than L-menthol and comparable activity
against An. tessellatus and Cx. quinquefasciatus, indi-
cating that the double bond in the cyclohexane ring
contributes to the mosquitocidal activity. The position
of the hydroxyl functionality, i.e. either in the cyclohex-
ane ring or in the branched chain of the molecule, may
affect the mosquitocidal activity because mugetanol
and α-terpineol both showed more mosquitocidal
activity against Cx. quinquefasciatus and Ae. aegypti
Menthol, a major constituent of M. piperita leaf
oil, showed more mosquitocidal activity against An.
tessellatus (LC50 0.36 and KD50 0.54 µg mL−1) and
Cx. quinquefasciatus (LC50 and KD50 0.50 µg mL−1
)
than minor constituents of the oil, i.e. men-
thone, β-caryophyllene, menthyl acetate and pulegone
(Table 1). However, M. piperita oil, menthol, men-
thone, β-caryophyllene, menthyl acetate and pulegone
showed either less or no activity against Ae. aegypti
(Table 1).
Synthesis of derivatives of L-menthol resulted
in 12 compounds, menthyl acetate, chloroacetate,
dichloroacetate, trifluoroacetate, propionate, chloro-
propionate, pivalate, benzoate, lactate and cinnamate,
menthyl methyl ether and a racemic mixture of men-
thone glyceryl acetal, in good yield (Fig. 2). The
structures of the above compounds were character-
ized by their 1H and 13C NMR spectral data and
by comparison with the reported data of the parent
compound.22,23
The 12 menthol derivatives synthesized (Fig. 2)
and two standard compounds, menthyl anthrani-
late and menthyl carboxamide, were tested for
knockdown effect and mortality against An. tessel-
latus, Cx. quinquefasciatus and Ae. aegypti following
the WHO protocol.24 Of the tested compounds,
menthyl chloroacetate showed the highest mortality
(LC50 0.08 µg mL−1) and menthone glyceryl acetal
the highest knockdown effect (KD50 0.19 µg mL−1
)
against An. tessellatus. Menthyl benzoate, dichloroac-
etate, chloropropionate, carboxamide and lactate
also showed good activity against An. tessellatus
(Table 1). Menthyl chloroacetate showed the high-
est activity against both Cx. quinquefasciatus and Ae.
aegypti, but the highest knockdown effect against Cx.
quinquefasciatus was shown by menthyl dichloroac-
etate (Table 1). Menthyl trifluoroacetate, propionate,
pivalate, benzoate and anthranilate were non-toxic
at 20 g L−1 against Cx. quinquefasciatus and Ae.
aegypti.
The mosquitocidal activity of L-menthol was com-
pared with its structurally similar analogues, L-
menthone, thymol, α-terpineol, pulegone and muge-
tanol. L-Menthol showed the highest mortality
(LC50 0.36 µg mL−1) and mugetanol the highest
knockdown effect (KD50 0.31 µg mL−1) against An.
tessellatus. Mugetanol showed the highest knockdown
effect against Ae. aegypti (KD50 0.36 µg mL−1) and α-
terpineol the highest mortality (LC50 0.62 µg mL−1).
Mugetanol showed the most activity against Cx. quin-
quefasciatus (KD50 and LC50 0.17 µg mL−1).
Menthol derivatives (Fig. 2) obtained by semi-
synthetic modifications of the hydroxyl group of L-
menthol showed enhanced mosquitocidal activity. Of
Pest Manag Sci 64:290–295 (2008)
293
DOI: 10.1002/ps

R Samarasekera, IS Weerasinghe, KDP Hemalal
294
Pest Manag Sci 64:290–295 (2008)
DOI: 10.1002/ps

Activity of menthol derivatives against mosquitoes
traditionally used as pesticides, and their insecticidal
properties against Chagas disease vectors. J Ethnopharmacol
52:145–149 (1996).
than L-menthol. It was also observed that the car-
bon–carbon double bond increased the mosquitocidal
activity in pulegone, which showed more activity than
L-menthone but less activity than L-menthol.
9 Samarasekera R, Kosmulalage KS and Weerasinghe IS,
Mosquitocidal activity of leaf and bark essential oils of Ceylon
Cinnamomum zeylanicum. J Essent Oil Res 17:301–303 (2005).
10 Samarasekera R, Kosmulalage KS and Weerasinghe IS, Insec-
ticidal activity of essential oils of Ceylon Cinnamomum and
Cymbopogon species against Musca domestica. J Essent Oil Res
18:352–354 (2006).
11 Pamela JR and Coats JR, Insecticidal properties of several
monoterpenoids to the housefly (Diptera: Muscidae), Red
Flour Beetle (Coleoptera: Tenebrionidae), and Southern
4
CONCLUSION
This is the first report of mosquitocidal activity of
menthol and its derivatives against An. tessellatus, Cx.
quinquefasciatus and Ae. aegypti. Derivative synthesis
followed by SAR studies identified several mosquito-
cidal compounds, i.e. menthyl chloroacetate, menthyl
dichloroacetate, menthyl cinnamate, menthone glyc-
eryl acetal, thymol, α-terpineol and mugetanol, which
showed good activity against local disease vector
mosquitoes, An. tessellatus, Cx. quinquefasciatus and
Ae. aegypti. These compounds have potential to be
developed as mosquitocidal compounds after toxico-
logical evaluation for vertebrates, including humans,
and ecotoxicological evaluations and commercial fea-
sibility studies. SAR studies of L-menthol derivatives
provided clear indications that minor structural and
functional group variations, i.e. shape, size and degree
of unsaturation, type of functional group and position
of functional group and type of derivatization, can
contribute towards enhancing mosquitocidal activity.
Corn Rootworm (Coeleoptera: Chrysomelidae).
J Econ
Entomol 87:1172–1179 (1994).
12 Edris AE and Farrag ES, Antifungal activity of Peppermint and
Sweet Basil essential oils and their major aroma constituents
on some plant pathogenic fungi from the vapor phase.
Nahrung/Food 47:117–121 (2003).
13 Lin R, Tian J, Huang G, Li T and Li F, Analysis of menthol in
three traditional Chinese medicinal herbs and their compound
formulation by GC-MS. Biomed Chromatogr 16:229–233
(2002).
14 Galeotti N, Mannelli LDC, Mazzanti G, Bartolini A and Ghe-
lardini C, Menthol: a natural analgesic compound. Neurosci
Lett 322:145–148 (2002).
15 Isman MB, Plant essential oils for pest and disease management.
Crop Prot 19:603–608 (2000).
16 Rice PJ and Coats JR, Insecticidal properties of monoterpenoid
derivatives to the house fly (Diptera: Muscidae) and red flour
beetle (Coleoptera: Tenebrionidae). Pestic Sci 41:195–202
(1994).
17 Hofle VG, Steglich W and Vorbruggen H, 4-Dialkylamino-
pyridine als hochwirksame Acylierungskatalysatoren. Angew
Chem 90:602–615 (1978).
ACKNOWLEDGEMENTS
18 Furniss BS, Hannaford AJ, Rogers V, Smith PWG and
Tatchell AR, Vogel’s Textbook of Practical Organic Chemistry,
4th edition. Longman Group Ltd, London, UK, pp. 843–846
(1978).
19 Zeng L, Fukai T, Nomura T, Zhang RY and Lou ZC, Phenolic
constituents of Glycyrrhiza species, Part 10, Glyasperin E, a
new 3-phenoxychromen-4-one derivative from the roots of
Glycyrrhiza aspera. J Chem Soc Perkin Trans I:1153–1159
(1993).
20 Almeida WP and Correia CRD, Stereoselective total synthesis
and enantioselective formal synthesis of the antineoplastic
sesquiterpenes quinone metachromin A. J Braz Chem Soc
10:401–414 (1999).
The authors thank SK Kosmulalage and WEU
Malewana for their assistance in derivative synthesis
and bioassay work, DCH Thirimanna for statictical
data analysis and Athar Ata at the Department
of Chemistry, University of Winnipeg, Canada, for
providing NMR spectral data for some of the
compounds. This work was financially supported by
the National Science Foundation, Sri Lanka (Grant
No, RG/C/ 02/2001).
21 Harwood LM and Moody CJ, Experimental Organic Chemistry
Principles and Practice. Blackwell Scientific Publications,
Oxford, UK, pp. 185–188 (1994).
REFERENCES
1 Karunaratne SPHP, Insecticide resistance in insects. Ceylon J
Sci (Biol Sci) 25:72–98 (1998).
22 Kubeczka KH and Formacek V, Essential Oils Analysis by Cap-
illary Gas Chromatography and Carbon-13 NMR Spectroscopy.
John Wiley & Sons, Ltd, Chichester, UK (2002).
23 Integrated Spectral Data Base System for Organic Compounds.
SDBS. [Online]. Available: http://riodbol.ibase.aist.go.jp/sdbs
/cgi-bin/direct-frame top.cgi [December 2004].
2 Karunaratne SPHP, Insecticide cross-resistance spectra and
underlying resistance mechanisms of Sri Lankan Anopheline
vectors of malaria. Southeast Asian J Trop Med Public Health
30:460–469 (1999).
3 Jarmyn RJ, Essential oils – myths and realities. Personal Care
28–31 May (2003).
24 Instructions for determining the susceptibility or resistance
of adult mosquitoes to organochlorine, organophosphate,
and carbamate insecticides-diagnostic test. World Health
Organization, WHO/VBC/81.806 (1976).
4 Tsao R and Coats JR, Starting from nature to make better
insecticides. Chemtech 23–28 July (1995).
5 Saxena BP and Koul O, Utilization of essential oils for insect
control. Indian Perfumer 22:139–149 (1978).
25 Collett D, Modelling Binary Data. Chapman and Hall, Boca
Raton, Florida (2002).
26 SPSS Version 10.0 for Windows. SPSS Inc., IL, USA
(1989–1999).
6 Rice PJ and Coats JR, Structural requirements for monoter-
penoid activity against insects, in Bioregulators for Crop Protec-
tion and Pest Control, ed. by Hedin PA. American Chemical
Society, Washington, DC, pp. 92–108 (1994).
27 Grodnitzky JA and Coats JR, QSAR evaluation of monoter-
7 Tsao R, Lee S, Rice PJ, Jensen C and Coats JR, Monoter-
penoids and their synthetic derivatives as leads for new insect-
control agents, in Synthesis and Chemistry of Agrochemicals
IV, ed. by Baker DR, Fenyes JG and Basarab GS. American
Chemical Society, Washington, DC, pp. 312–324 (1995).
8 Fournet A, de Arias AR, Charles B and Bruneton J, Chemical
constituents of essential oils of Muna, Bolivian plants
penoids’ insecticidal activity.
J
Agric Food Chem
50:4576–4580 (2002).
28 Samarasekera R, Weerasinghe IS and Hemalal KDP, In pursuit
of mosquitocidal compounds from plant essential oils. Int
Symp Chemistry of Essential Oils, Terpenes and Aromatics,
Tokushima, Japan, 18–21 October (2002).
Pest Manag Sci 64:290–295 (2008)
295
DOI: 10.1002/ps