ArticlePDF Available

Essential Oils as Green Pesticides: Potential and Constraints

  • Insect Biopesticide Research Centre


Content may be subject to copyright.
2008 Koul et al. : Essential oils as green pesiticides 63
* Corresponding author: E-mail:;
Essential Oils as Green Pesticides: Potential and Constraints
Insect Biopesticide Research Centre, 30 Parkash Nagar, Jalandhar 144003, India;
Division of Agricul-
tural Chemicals, Indian Agricultural Research Institute, New Delhi 110012, India
Biopestic. Int. 4(1): 6384 (2008)
ABSTRACT Many plant essential oils show a broad spectrum of activity against pest insects and
plant pathogenic fungi ranging from insecticidal, antifeedant, repellent, oviposition deterrent,
growth regulatory and antivector activities. These oils also have a long tradition of use in the
protection of stored products. Recent investigations indicate that some chemical constituents of
these oils interfere with the octopaminergic nervous system in insects. As this target site is not
shared with mammals, most essential oil chemicals are relatively non-toxic to mammals and fish
in toxicological tests, and meet the criteria for “reduced risk” pesticides. Some of these oils and
their constituent chemicals are widely used as flavoring agents in foods and beverages and are
even exempt from pesticide registration. This special regulatory status combined with the wide
availability of essential oils from the flavor and fragrance industries, has made it possible to fast-
track commercialization of essential oil-based pesticides. Though well received by consumers for
use against home and garden pests, these “green pesticides” can also prove effective in agricultural
situations, particularly for organic food production. Further, while resistance development continues
to be an issue for many synthetic pesticides, it is likely that resistance will develop more slowly
to essential-oil-based pesticides owing to the complex mixtures of constituents that characterize
many of these oils. Ultimately, it is in developing countries which are rich in endemic plant
biodiversity that these pesticides may ultimately have their greatest impact in future integrated
pest management (IPM) programmes due to their safety to non-target organisms and the environment.
KEY WORDS : Essential oils, green pesticides, monoterpenes, phytochemicals, antifeedants,
repellents, fumigants, commercialization
0973-483X/08/63-84©2008 (KRF)
The environmental problems caused by overuse
of pesticides have been the matter of concern for
both scientists and public in recent years. It has been
estimated that about 2.5 million tons of pesticides
are used on crops each year and the worldwide
damage caused by pesticides reaches $100 billion
annually. The reasons for this are two fold: (1) the
high toxicity and nonbiodegradable properties of
pesticides and (2) the residues in soil, water resources
and crops that affect public health. Thus, on the one
hand, one needs to search the new highly selective
and biodegradable pesticides to solve the problem
of long term toxicity to mammals and, on the other
hand, one must study the environmental friendly
pesticides and develop techniques that can be used
to reduce pesticide use while maintaining crop yields.
Natural products are an excellent alternative to
synthetic pesticides as a means to reduce negative
impacts to human health and the environment. The
move toward green chemistry processes and the
continuing need for developing new crop protection
tools with novel modes of action makes discovery
and commercialization of natural products as green
64 Biopesticides International Vol. 4, no. 1
pesticides an attractive and profitable pursuit that is
commanding attention. The concept of “Green
Pesticides” refers to all types of nature-oriented and
beneficial pest control materials that can contribute
to reduce the pest population and increase food
production. They are safe and ecofriendly. They are
more compatible with the environmental components
than synthetic pesticides (Isman and Machial, 2006).
Thus in the present concept of green pesticides,
some rational attempts have been made to include
substances such as plant extracts, hormones,
pheromones and toxins from organic origin and
also encompass many aspects of pest control such
as microbial, entomophagous nematodes, plant-
derived pesticides, secondary metabolites from
microorganisms, pheromones and genes used to
transform crops to express resistance to pests. More
recently, the encouragement of use of products from
natural resources and even the extremely
biodegradable synthetic and semisynthetic products
in pest management, has been considered to constitute
the umbrella of green pesticides (Koul et al., 2003;
Koul 2005; Dhaliwal and Koul, 2007; Koul, 2008).
However, it will be beyond the scope of any article
to discuss all of them at one place. Here we shall
like to emphasize on some recent developments
where essential oils have been projected as safe and
commercially viable green pesticides with some
recent commercial developments along with their
potential and constraints.
Essential oils are defined as any volatile oil(s)
that have strong aromatic components and that give
distinctive odour, flavour or scent to a plant. These
are the by-products of plant metabolism and are
commonly referred to as volatile plant secondary
metabolites. Essential oils are found in glandular
hairs or secretory cavities of plant-cell wall and are
present as droplets of fluid in the leaves, stems, bark,
flowers, roots and/or fruits in different plants. The
aromatic characteristics of essential oils provide
various functions for the plants including (i) attracting
or repelling insects, (ii) protecting themselves from
heat or cold; and (iii) utilizing chemical constituents
in the oil as defence materials. Many of the essential
oils have other uses as food additives, flavourings,
and components of cosmetics, soaps, perfumes,
plastics, and as resins.
Typically these oils are liquid at room
temperature and get easily transformed from a liquid
to a gaseous state at room or slightly higher temp-
erature without undergoing decomposition. The
amount of essential oil found in most plants is 1 to
2%, but can contain amounts ranging from 0.01 to
10%. For example, orange tree produce different
composition of oils in their blossoms, citrus fruits,
and/or leaves. In certain plants, one main essential
oil constituent may predominate while in others it is
a cocktail of various terpenes. In Ocimum basilicum
(basil), for example, methyl chavicol makes up 75%
of the oil, β-asarone amounts to 70–80% in Acorus
calamus rhizomes, linalool , in the range of 50–
60%, occurs in coriander seed and leaf oils procured
from different locations at different time intervals
and is by far the most predominant constituent
followed by p-cymene, terpinene, camphor and
limonene. Interestingly 2-decenol and decanal were
the most predominant constituents in leaf oil (Law-
rence and Reynolds, 2001). However, in other species
there is no single component which predominates.
Most essential oils comprise of monoterpenes -
compounds that contain 10 carbon atoms often
arranged in a ring or in acyclic form, as well as
sesquiterpenes which are hydrocarbons comprising
of 15 carbon atoms. Higher terpenes may also be
present as minor constituents. The most predominant
groups are cyclic compounds with saturated or
unsaturated hexacyclic or an aromatic system.
Bicyclic (1,8-cineole) and acyclic (linalool,
citronellal) examples also make the components of
essential oils. However, intraspecific variability in
chemical composition does exist, which is relative
to ecotypic variations and chemotypic races or
Naturally green concept suggests the avoidance
of use of any pesticide via public education and
awareness-raising program, developed to inform
public about the potential risk of pesticide use and
alternatives that are available. In fact, such programs
support the policy of “prudent avoidance”. Various
2008 Koul et al. : Essential oils as green pesiticides 65
steps suggested in these programs are overseeding,
high mowing, grass cycle, compost spread, deep root
watering, core aeration, slow release soil feeding,
use of beneficial organisms, etc. This concept is very
useful for kitchen garden, lawn and other domestic
pest control strategy. Use of essential oils or their
components add to this natural concept owing to
their volatility, limited persistence under field
conditions and several of them having exemption
under regulatory protocols.
Essential oils are usually obtained via steam
distillation of aromatic plants, specifically those used
as fragrances and flavourings in the perfume and
food industries, respectively, and more recently for
aromatherapy and as herbal medicines. Plant essential
oils are produced commercially from several
botanical sources, many of which are members of
the mint family (Lamiaceae). The oils are generally
composed of complex mixtures of monoterpenes,
biogenetically related phenols, and sesquiterpenes.
Examples include 1,8-cineole, the major constituent
of oils from rosemary and eucalyptus; eugenol from
clove oil; thymol from garden thyme; menthol from
various species of mint; asarones from calamus; and
carvacrol and linalool from many plant species. A
number of source plants have been traditionally used
for protection of stored commodities, especially in
the Mediterranean region and in Southern Asia, but
interest in the oils was renewed with emerging
demonstration of their fumigant and contact
insecticidal activities to a wide range of pests in the
1990s (Isman, 2000). The rapid action against some
pests is indicative of a neurotoxic mode of action,
and there is evidence for interference with the
Table 1. Mammalian toxicity of some essential oil compounds
Compound Animal tested Route LD
2-Acetonaphthone Mice Oral 599
Apiol Dogs Intravenous 500
Anisaldehyde Rats Oral 1510
trans-Anethole Rats Oral 2090
(+) Carvone Rats Oral 1640
1,8-Cineole Rats Oral 2480
Cinnamaldehyde Guinea pigs Oral 1160
Rats Oral 2220
Citral Rats Oral 4960
Dillapiol Rats Oral 1000–1500
Eugenol Rats Oral 2680
3-Isothujone Mice Subcutaneous 442.2
d-Limonene Rats Oral 4600
Linalool Rats Oral
> 1000
Maltol Rats Oral 2330
Menthol Rats Oral 3180
2-Methoxyphenol Rats Oral 725
Methyl chavicol Rats Oral 1820
Methyl eugenol Rats Oral 1179
Myrcene Rats Oral 5000
Pulegone Mice Intraperitoneal 150
γ-terpinene Rats Oral 1680
Terpinen-4-ol Rats Oral 4300
Thujone Mice Subcutaneous 87.5
Thymol Mice Oral 1800
Rats Oral 980
Source: Dev and Koul (1997); FAO (1999); Koul (2005)
66 Biopesticides International Vol. 4, no. 1
neuromodulator octopamine (Kostyukovsky et al.,
2002) by some oils and with GABA-gated chloride
channels by others (Priestley et al., 2003). The
purified terpenoid constituents of essential oils are
moderately toxic to mammals (Table 1), but, with
few exceptions, the oils themselves or products based
on oils are mostly nontoxic to mammals, birds, and
fish (Stroh et al., 1998), therefore, justifying their
placement under “green pesticides”. Owing to their
volatility, essential oils have limited persistence under
field conditions; therefore, although natural enemies
are susceptible via direct contact, predators and
parasitoids reinvading a treated crop one or more
days after treatment are unlikely to be poisoned by
residue contact as often occurs with conventional
insecticides. In fact, effects on natural enemies have
yet to be evaluated under field conditions. Recent
evidence for an octopaminergic mode-of-action for
certain monoterpenoids (Bischof and Enan 2004;
Kostyukovsky et al., 2002), combined with their
relative chemical simplicity may yet find these natural
products useful as lead structures for the discovery
of new neurotoxic insecticides with good mammalian
There are several examples of essential oils like
that of rose (Rosa damascene), patchouli (Pog-
ostemon patchouli), sandalwood (Santalum album),
lavender (Lavendula officinalis), geranium (Pela-
rgonium graveolens), etc. that are well known in
perfumery and fragrance industry. Other essential
oils such as lemon grass (Cimbopogon winteriana),
Eulcalyptus globulus, rosemary (Rosemarinus offic-
inalis), vetiver (Vetiveria zizanoides), clove (Eugenia
caryophyllus) and thyme (Thymus vulgaris) are
known for their pest control properties. While
peppermint (Mentha piperita) repels ants, flies, lice
and moths; pennyroyal (Mentha pulegium) wards
off fleas, ants, lice, mosquitoes, ticks and moths.
Spearmint (Mentha spicata) and basil (Ocimum
basilicum) are also effective in warding off flies.
Similarly, essential oil bearing plants like Artemesia
vulgaris, Melaleuca leucadendron, Pelargonium ros-
eum, Lavandula angustifolia, Mentha piperita, and
Juniperus virginiana are also effective against various
insects and fungal pathogens (Kordali et al., 2005).
Studies conducted on the effects of volatile oil
constituents of Mentha species are highly effective
against Callosobruchus maculatus and Tribolium
castanum, the common stored grain pests (Tripathi
et al., 2000). Essential oils derived from eucalyptus
and lemongrass have also been found effective as
animal repellents, antifeedants, insecticides, miticides
and antimicrobial products; thus finding use as
disinfectants, sanitizers, bacteriostats, microbiocides,
fungicides and some have made impact in protecting
household belongings.
Essential oil from Cinnamomum zeylanicum,
Cymbopogon citratus, Lavandula angustifolia syn.
L. officinalis, Tanacetum vulgare, Rabdosia meli-
ssoides, Acorus calamus, Eugenia caryophyllata,
Ocimum spp., Gaultheria procumbens, Cuminum
cymium, Bunium persicum, Trachyspermum ammi,
Foeniculum vulgare, Abelmoschus moschatus, Ced-
rus spp. and Piper species are also known for their
varied pest control properties.
Citronella (Cymbopogon nardus) essential oil
has been used for over fifty years both as an insect
repellent and an animal repellent. Combining few
drops each of citronella, lemon (Citrus limon), rose
(Rosa damascena), lavender and basil essential oils
with one litre of distilled water is effective to ward
off indoor insect pests. The larvicidal activity of
citronella oil has been mainly attributed to its major
monoterpenic constituent citronellal (Zaridah et al.,
Vetiver (Vetiveria zizanioides) essential oil
obtained by steam distillation of aromatic roots con-
tains a large number of oxygenated sesquiterpenes.
This oil is known to protect clothes and other valu-
able materials from insect attack when placed in
closets, drawers, and chests.
Catnip (Nepeta cateria) essential oil is highly
effective for repelling mosquitoes, bees and other
flying insects. The most active constituent in catnip
has been identified as nepetalactone. It repels
mosquitoes ten times more than DEET. It is
particularly effective against Aedes aegypti mosquito,
a vector for yellow fever virus. Oil of Trachy-
spermum sp. is also larvicidal against A. aegypti and
southern house mosquito, Culex quinquefasciatus Say
= 93.19–150.0 ppm) (Vrushali et al., 2001).
2008 Koul et al. : Essential oils as green pesiticides 67
Similalrly, essential oils of Ocimum sanctum
caused 20% mortality to 3
instar S. litura larvae
(Sharma et al., 2001). At a topical dose of 100 µg/
larvae, > 90% larval mortality has been reported
when essential oil of Satoreja hortensis, Thymus
serpyllum and Origanum creticum (LD
= 48.4–53.4)
were applied to 3
instars S. litura (Isman et al.,
2001). Similar studies were reported by Sharda et
al. (2000) where essential oil of Ageratum conyzoides
caused 43.0–68.75% mortality at 0.025–0.25 µl
concentration. Tripathi et al., (2003) has reported
toxicity of essential oil of Aegle marmelos by topical
application to S. litura larvae with LD
= 116.3 µg/
larvae. Essential oil of Lippia alba induces growth
inhibition (GI
= 6.9–11.0 mg/g diet), where both
relative growth and feeding consumption rates of S.
litura were conspicuously reduced (Tripathi et al.,
Dill oil obtained from dill plant (Anethum sowa)
as by-product of dill industry is also a rich source of
carvone. The other major constituent of A. sowa
namely dillapiole is well known for its insecticide
synergistic properties. It also occurs to the extent of
about 40–60% in Anethum graveolens seed oil and
more than 51% in spearmint oil (Mentha spicata).
The turmeric (Curcuma longa) leaves, the unutilized
part of turmeric plant, on hydrodistillation yields oil
rich in α-phellandrene (70%). This oil induces growth
inhibition and larval mortality against Spilosoma
obliqua (Agarwal et al., 1999). The leaf oil is also
ovicidal and nymphicidal against Dysdercus koenigii
and induces moderate knockdown effect against T.
castaneum. Curcumene and ginger oil at 0.2%
concentration induces 86% inhibition of the mycelial
growth of the test fungus Rhizoctonia solani. Thus,
collective assessment of essential oil efficacy as green
pesticides suggests that some oils are significantly
more active than others. However, more empirical
evaluation of active components using wide array of
pest species would reveal valuable and specific
biological activities as discussed in next section.
As mentioned above essential oils are complex
mixtures of natural organic compounds which are
predominantly composed of terpenes (hydrocarbons)
such as myrecene, pinene, terpinene, limonene, p-
cymene, α- and β- phellandrene etc.; and terpenoids
(oxygen containing hydrocarbons) such as acyclic
monoterpene alcohols (geraniol, linalool), monocy-
clic alcohols (menthol, 4-carvomenthenol, terpineol,
carveol, borneol,), aliphatic aldehydes (citral, cit-
ronellal, perillaldehyde), aromatic phenols (carvac-
rol, thymol, safrol, eugenol), bicyclic alcohol
(verbenol), monocyclic ketones (menthone, pulegone,
carvone), bicyclic monoterpenic ketones (thujone,
verbenone, fenchone), acids (citronellic acid, cin-
namic acid) and esters (linalyl acetate). Some es-
sential oils may also contain oxides (1,8- cineole),
sulphur containing constituents, methyl anthranilate,
coumarins, etc. Zingiberene, curcumene, farnesol,
sesquiphellandrene, termerone, nerolidol, etc. are
examples of sesquiterpenes (C
) isolated from es-
sential oils. Mono- and sesquiterpenoidal essential
oil constituents are formed by the condensation of
isopentenyl pyrophosphate units. Diterpenes usu-
ally do not occur in essential oils but are sometimes
encountered as by-products. Chemical structures of
some of the essential oil constituents are given in
Fig. 1 and many among them possess potent bio-
logical activity and are responsible for the bitter taste
and toxic properties.
Insecticides and Growth Inhibitors
Essential oil constituents are primarily lipophilic
compounds that act as toxins, feeding deterrents and
oviposition deterrents to a wide variety of insect-
pests. Insecticidal properties of several monoter-
penoids to the housefly, red flour beetle and south-
ern corn root-worm have been reported (Rice and
Coats, 1994). Although many monoterpenoids have
insecticidal properties, the degree of toxicity of dif-
ferent compounds to one species differs consider-
ably. Cornelius et al. (1997) evaluated toxicity of
monoterpenoids against Coptotermes formosanus
(a subterranean termite) of which eugenol was found
most effective as termiticide. It was also effective as
a fumigant and as feeding deterrent. Eugenol is also
reported as toxic to asian armyworm, Spodoptera
litura Fabricius, granary weevil, Sitophilus grana-
68 Biopesticides International Vol. 4, no. 1
2008 Koul et al. : Essential oils as green pesiticides 69
Fig. 1. Chemical structures of essential oil constituents
70 Biopesticides International Vol. 4, no. 1
ries (Linnaeus), common house fly, Musca domestica
Linnaeus and western corn root worm, Diabrotica
virgifera Lee Conte, (LD
= 2.5–157.6 µg/insect)
(Hummelbrunner and Isman, 2001; Obeng-Ofori and
Reichmuth, 1997; Lee et al., 1997). Eugenol is also
active against Drosophila melanogaster Meigen,
yellow fever mosquito, Aedes aegypti (Linnaeus) and
American cockroach, Periplanata americana
(Linnaeus) (Bhatnagar et al., 1993; Ngoh et al.,
1998). Similarly, thymol induces toxicity in M.
domestica and S. litura (LD
= 25.4–29.0 µg/in-
sect) (Lee et al., 1997; Hummelbrunner and Isman,
2001) and is also toxic to D. melanogaster and north-
ern house mosquito, Culex pipiens Linnaeus
(Franzios et al., 1997; Traboulsi et al., 2002). Cit-
ronellal is toxic to S. litura, M. domestica (LD
66.0–111.2 µg/insect; Hummelbrunner and Isman,
2001; Lee et al., 1997), cowpea weevil, Callo-
sobruchus maculatus (Fabricius) and D. melan-
ogaster (Don-Pedro, 1996). d-Limonene in the range
of 50–273.7 µg/insect is toxic to M. domestica, D.
virgifera, S. litura (Lee et al., 1997; Hummelbrunner
and Isman, 2001) and some stored grain pests and
cockroaches (Don- Pedro, 1996; Lee et al., 2001;
Coats et al., 1991). Similarly, limonene found in the
essential oil of various citrus leaves and fruit peels
have exhibited significant insect control properties
(Karr and Coats, 1988). Menthone, trans-anethole
and cinnamaldehyde are well known anti-insect com-
pounds that have been studied against variety of in-
sects with wide range of dosage required to kill 50%
population (65–1735 µg/insect) (Marcus and
Lichtenstein, 1979; Harwood et al., 1990; Lee et
al., 1997; Franzios et al., 1997; Hung and Ho, 1998;
Hummelbrunner and Isman, 2001; Chang and Ahn,
2001; Lee et al., 2001; Chang and Cheng, 2002).
Meepagala et al. (2006) found that apiol isolated
from Ligusticum hultenii exhibited high termiticidal
activity of 100% within 11 days after treatment and
similar effect was shown by vulgarone B, isolated
from Artemisia douglasiana, where as cnicin iso-
lated from Centaurea maculosa showed mortality of
81% within 15 days after treatment when applied at
1.0% (w/w) concentration to these termites. Citral
(3,7-dimethyl 2,6-octadienal), the most important
member of acyclic monoterpenoids is a liquid which
has smell of lemon and occurs to an extent of 60–
80% in lemon grass oil. Due to the presence of one
α, β -unsaturated moiety, it occurs as a mixture of E
(trans) and Z (cis) geometric isomers. These iso-
mers are referred as geranial and neral, respectively
but do not show much potential in pest control.
Lichtenstein et al. (1974) have reported that
carvone isolated from aerial parts of dill plants
(Anethum graveolus Linnaeus) was insecticidal to
Drosophilla and Aedes spp. It also suppressed larval
and adult survival (Ouden et al., 1993). Lee et
al. (1997) evaluated acute toxicity of 34 naturally
occurring monoterpenoids against three insect spe-
cies. They reported that citronellic acid and thymol
were the most toxic against house fly, while cit-
ronellol and thujone were most effective against the
western corn root worm. Hierro et al. (2004) has
reported the action of different monoterpenic com-
pounds against Anisakis simplex larvae and found
that geraniol, citronellol, citral, carvacrol and
cuminaldehyde were active at 12.5 µg/ml concentra-
Eugenol from cloves, Eugenia cryophyllus; 1,8-
cineole from Eucalyptus globules; citronellal from
lemon grass, Cymbopogon nardus; pulegone from
Mentha pulegium, and thymol and carvacrol from
Thymus vulgaris are among the most active con-
stituents against insects. Eugenol shows variable LD
values which are purely species specific. Pulegone
is shown to be effective against M. domestica, D.
virgifera, P. saucia and, S. litura in the range of
= 38–753.9 µg/insect (Lee et al., 1997;
Harwood et al., 1990; Hummelbrunner and Isman,
2001). Pulegone containing diet at 0.1% retarded
development and inhibited reproduction of last in-
star of southern armyworm, Spodoptera eridania
(Cramer) (Gunderson et al., 1985). Pulegone has
also been observed to be more toxic than l-menthol
against european corn borer, Ostrinia nubilalis
(Hubner) 1
instar, where as reverse toxicity was
observed against 2
instar (Lee et al., 1999).
Substituted phenols such as eugenol, methyl
eugenol, isoeugenol, safrole, isosafrole are better
toxicants and repellents than monoterpenes, such as
2008 Koul et al. : Essential oils as green pesiticides 71
limonene, cineole and p-cymene. The essential oil
from root of sweet flag, Acorus calamus is also known
for its insecticidal and antigonadal actions associated
with its most abundant constituent β - asarone (Koul et
al., 1990; Koul, 1995). A. calamus has been shown to
induce mortality of 80.87% in 3
instars of Spilarctia
obliqua (Walker) in laboratory and 74.26% under field
conditions at 2.0% concentration (Dubey et al., 2004).
According to Raina et al., (2007) orange oil
extracted from citrus peel (containing ~92% d-
limonene) caused 96 and 68% mortality to formosan
subterranean termite, Coptotermes formosanus
Shiraki within 5 days and there was significant
reduction in feeding as compared to controls at 5
ppm concentration (v/v), also the termites did not
tunnel through glass tubes fitted with sand treated
with 0.2–0.4% orange oil extract. Catnip oil derived
from Nepeta cataria and its two major components
E, Z- nepetalactone, Z, E-nepetalactone monoterpenes
at 40 mg/cm
caused 100% mortality to formosan
subterranean termite, C. formosanus after one day,
where as at 20 mg/cm
97% mortality was achieved
by E, Z- nepetalactone within 7 days which also
determined its repellent action by preventing termites
to tunnel through a 60 mm glass tube filled with
sand treated at 200 ppm (Chauhan and Raina, 2006).
Acaricidal activities of various essential oils have
been assessed and found toxic to honey bee mite,
Acarapis woodi (Rennie), (Ellis and Baxendale,
1997), varroa mite, Varroa jacobsoni Oudemans
(Calderone and Spivak, 1995), northern fowl mite,
Ornithonyssus sylviarum (Canestrini and Fanzago)
(Carroll, 1994), grain mite, Tyrophagus longior
Gervais, (Perrucci, 1995), scab mite, Psoroptes
cuniculi (Delafond), (Perrucci et al., 1995), two
spotted spider mite, Tetranychus urticae Koch
(Chiasson et al., 2001), Dermatophagoides ptero-
nyssinus (Trouessart) and American house dust mite,
Dermatophagoides farinae Huges, (Yatagi et al.,
1997) and T. urticae (Lee et al., 1997). Choi et al.
(2004) has evaluated 53 plant essential oils against
T. urticae and Phytoseilus persimilis. Among pure
constituents citronellal, eugenol, menthol, pulegone,
and thymol are moderately active against various
mites (Calderone and Spivak, 1995; Perrucci et al.,
1995; Ellis and Baxendale, 1997). Essential oils rich
in 1,8-cineole are also effective against house dust
mites (Miresmailli et al., 2006). These studies
indicate that such compounds can make substantial
impact as commercial products, if suitable delivery
systems are developed.
Beninger et al., (1993) has shown that diterpene
3-epicaryotin reduced growth of european corn borer
larvae when incorporated into artificial diet and pu-
pal deformities and time to pupation also increased.
Menthol reduced growth and inhibited pupation of
the variegated cutworm, Peridroma saucia (Hubner)
(Harwood et al., 1990). d- Limonene, linalool, α-
myrcene and α-terpineol significantly increased the
nymphal duration in German cockroach, Blattella
germanica (Linnaeus) when fed through artificial
diet (Karr and Coats, 1992). 1, 8 Cineole isolated
from Artemisia annua is also a potential insecticidal
allelochemical that could reduce the growth rate,
food consumption and food utilization in some post
harvest pests and house hold insects (Jacobson and
Halber, 1947; Klocke et al., 1989; Obeng and
Reichmuth, 1997). Similar effects against O. nubilalis
(reared from 1
instars on diet) have been recorded
with carveol, 4-carvomenthenol, l-carvone, citronel-
lal, geraniol, isopulegol, limonene, linalool, l-men-
thol, perillaldehyde, peril alcohol, α-pinene,
pulegone, α-terpineol, thujone, thymol, 2-fluoro ethyl
thymol ether (a fluorinated thymol derivative MTEE-
25), MTEE-35, MTEE-76, MTEE-90, MTEE-99 and
MTEE-P in the concentration range of 0.02–20.0
mg/g diet (Lee et al., 1999). The LC
value of
MTEE-25 was 6 times more than its parent com-
pound thymol to 1
instars of O. nubilalis.
Turmeric plant oil is also very useful in pest
control. The turmeric leaves and unutilized parts of
turmeric plant, on hydrodistillation yields oil rich in
2-phellandrene (70%) that inhibits growth of S.
obliqua and diamond back moth, Plutella xylostella
(Linnaeus) at 1.0 % concentration (Govindaraddi,
2005; Walia, 2005).
Monoterpenes being volatile are more useful as
insect fumigants. Several studies have been under-
taken in the past to explore the potential of essential
72 Biopesticides International Vol. 4, no. 1
oils and their constituents as insect fumigants.
Pulegone, linalool and limonene are known effec-
tive fumigants against rice weevil, Sitophilus oryzae.
While Mentha citrata oil containing linalool and
linalyl acetate exhibit significant fumigant toxicity
to these rice weevils (Singh et al., 1989), l-carvone
has been reported to cause 24 times more fumigant
toxicity than its contact toxicity to lesser grain borer,
Rhizopertha domestica (Tripathi et al., 2003).
Carvone was similarly effective as adulticide while
menthol was most effective as fumigant against T.
castaneum and C. maculatus. 1,8-cineole on the other
hand exhibits both contact and fumigant toxicity
when tested against T. castaneum (Tripathi et
al., 2001). The adults were more susceptible than
the larvae to both contact and fumigant toxicity.
Number of compounds has been evaluated as fumi-
gants against Musca domestica and T. castaneum.
(µg/l) values have been determined for car-
vacrol, carveol, geraniol, linalool, menthol, terpin-
eol, thymol, verbenol, carvones, fenchone, menthone,
pulegone, thujone, verbenone, cinnamaldehyde, ci-
tral, citronellal, and cinnamic acid (Rice and Coats,
1994). These studies reveal that ketones were more
effective as fumigants.
Trans-anethole, thymol, 1,8-cineole, carvacrol,
terpineol, and linalool have been evaluated as fumi-
gants against T. castaneum. Only compound to show
significant effect against this insect species was trans-
anethole and red flour beetles seemed to be least
susceptible to most of the other compounds up to
300 µl/l fumigation. Anethole has shown significant
effect on population from 20 µl/l concentration (66%
reduction in population), which touched to 98% at
80 µl/l level and beyond this there was absolute
control of population generation. For improving the
mortality effect of anethole, minimum heat treatment
C) device was used that enhanced the toxicity of
adults by 2-fold at 50.0 µl/l and 100.0 µl/5l treat-
ment, respectively. Among various combinations of
compounds used anethole combined with 1,8-cin-
eole (1:1) was the best. This combination reduced
the population by 100% at 50µl/l concentration and
at the same time was toxic to adults as well. As T.
castaneum was resistant to most of the compounds,
a workable gelatin capsule formulation (IBRC-
TACT) based on combination of four compounds
has been developed, which reduced the progeny by
100%. A significant observation has been that when
treatment was continued for larvae in 5-litre jars
(with feeding medium) and insects were allowed to
complete life cycle under treated conditions the
freshly emerged adults coming to the surface of the
feeding medium were dead within 12 h. This sug-
gests that freshly emerged adults were highly sus-
ceptible to the treatment of anethole or IBRC-TACT
and could not withstand the effect of compounds.
One of the plausible explanations for such an effect
could be the interference during the sclerotization
immediately after the emergence from pupae, which
ultimately leads to the death of beetles within 12 h
of their emergence (Koul et al., 2007).
Antifeedant chemicals may be defined as being
either repellent without making direct contact to in-
sect, or suppressant or deterrent from feeding once
contact has been made with insects. Essential oil
constituents such as thymol, citronellal and α-terpi-
neol are effective as feeding deterrent against to-
bacco cutworm, S. litura and synergism or additive
effects of combination of monoterpenoids from es-
sential oils have been reported against S. litura lar-
vae (Hummelbrunner and Isman, 2001). Bioefficacy
of Eucalyptus camaldulensis var. obtusa and
Luvanga scandans essential oils has also been de-
termined against S. litura larvae. Biogenically re-
lated monoterpenoids, the 1,8-cineole from Euca-
lyptus camaldulensis var. obtusa and linalool from
Luvanga scandans species were found to be most
active isolates from these plants via topical applica-
tion. Linalool was more active (LD
= 85.5 µg/
larva) than 1,8-cineole (LD
= 126.6 µg/larva). Vari-
ous known monoterpenoids have been used as bi-
nary mixtures and tested for synergy, using toxicity
and feeding inhibition parameters. The data suggests
that thymol and trans-anethole synergized the ef-
fects of linalool (at 18 µg/larva dose, combined in
1:1 ratio) but thymol with 1,8-cineole exhibited only
additive effect and so was the case with terpineol
2008 Koul et al. : Essential oils as green pesiticides 73
and linalool combination. A definite synergism was
also observed in case of isolated compounds from
two different plant species, i.e. linalool with 1,8-
cineole (Singh et al., 2008).
Antifeedant activity of 1,8- cineole has also been
demonstrated against T. castaneum (Tripathi et
al., 2001). In another study (Paruch et al., 2000), a
terpenoid lactone exhibited antifeeding activity
against granary weevil, Sitophilus granarium; the
khapra beetle, Trogoderma granarium; and confused
flour beetle, T. confusum. The activity was compa-
rable to the neem biopesticide. Feeding deterrence
activities of leaf essential oil of Curcuma longa
against adult and larvae of grain borer, R. domestica;
rice weevil, S. oryzae; and red flour beetle, T.
castaneum has been attributed to the presence of
monoterpenes, carvone and dihydrocarvone (Tripathi
et al., 2003). Products isolated/derived from Cur-
cuma longa (turmeric) and Zingiber officinale (gin-
ger) have also been found effective as insect
antifeedant and insect growth regulators (Chowdhury
et al., 1999; Agarwal et al., 2000; Agarwal and
Walia, 2003).
Koschier and Sedy, (2001) studied the
antifeedant effect of essential oil of majoram and
rosemary oil (Rosemarinum officinalis) at 0.1–1.0%
concentration against onion thrips, Thrips tabaci
Lindeman. Essential oils of Ocimum sanctum, O.
basilicum, Cymbopogon winterianus, Callistemon
lanceolatus and Vitex negundo caused 100% feed-
ing deterrence at 10% concentration. Considerable
feeding inhibition (70.21–80.21%) was recorded for
instars of S. obliqua when treated with 0.4%
concentration of Artemisia nilagarica and Juglans
regia var. kumaonica oils, while at 0.3% these oils
induced feeding deterrence of 63.12–83.76% among
instars of S. litura (Chowdhury et al., 2000).
Essential oils from Elsholtzia densa, E. incise and
E. piulosa also showed significant antifeedant activ-
ity against 3
instars of S. litura (Shishir et al., 2004).
Highest feeding deterrence of 76.4% was observed
in H. armigera with essential oil of Aegle marmelos
(Tripathi et al., 2003). These oils are rich in 1,8-
cineole, linalool, eugenol, carvacrol and thymol,
which are known compounds to show effects against
various insect species and fumigant activity in above
cases could be attributed to them in the respective
essential oils.
Vector-borne diseases caused by A. aegypti and
other mosquitoes have become global health problem.
Though thousands of plants have been tested as
potential sources of
insect repellents, only a few plant-
derived chemicals
tested to date demonstrate the
broad effectiveness and duration as good as DEET
(Cockcroft et al., 1998). Recently, a review of
botanical phytochemicals with mosquitocidal
potential has been published (Shaalan et al., 2005),
demonstrating identification of novel effective
mosquitocidal from botanicals containing active
phytochemicals. The review gives current state of
knowledge on larvicidal plant species, extraction
processes, growth and reproduction inhibiting
phytochemicals, botanical ovicides, synergistic,
additive and antagonistic joint action effects of
mixtures, residual capacity, effects on non-target
organisms, resistance, screening methodologies, and
discuss promising advances made in phytochemical
research for vector control.
Similarly, laboratory bioassays were conducted
to determine the activity of 15 natural products iso-
lated from essential oil components extracted from
the heartwood of Alaska yellow cedar, Cham-
aecyparis nootkatensis (D. Don) Spach., against Ix-
odes scapularis Say nymphs, Xenopsylla cheopis
(Rothchild), and Aedes aegypti (L.) adults. Four of
the compounds from the essential oil have been iden-
tified as monoterpenes, five as eremophilane ses-
quiterpenes, five as eremophilane sesquiterpene de-
rivatives from valencene and nootkatone, and one as
a sesquiterpene outside the eremophilane parent
group. Carvacrol was the only monoterpene that dem-
onstrated biocidal activity against ticks, fleas, and
mosquitoes with LC
values of 0.0068, 0.0059, and
0.0051% (w/v), respectively after 24 h. Nootkatone
from Alaska yellow cedar was the most effective of
the eremophilane sesquiterpenes against ticks (LC
= 0.0029%), whereas the nootkatone from grape-
fruit extract exhibited the greatest biocidal activity
against fleas (LC
= 0.0029%). Mosquitoes were
74 Biopesticides International Vol. 4, no. 1
most susceptible to one of the derivatives of
valencene, valencene-13-aldehyde (LC
= 0.0024%),
after 24 h. Bioassays to determine residual activity
of the most effective products were conducted at 1,
2, 4, and 6 wk after initial treatment. Residual LC
values for nootkatone did not differ significantly at
4 wk post-treatment from the observations made at
the initial 24 h treatment. The ability of these natu-
ral products to kill arthropods at relatively low con-
centrations also represents an alternative to the use
of synthetic pesticides for control of disease vectors
(Panella et al., 2005; Dietrich et al., 2006). Repel-
lency of oils of lemon, eucalyptus, geranium, and
lavender have also been recorded against Ixodes rici-
nus (Acari: Ixodidae) in the laboratory and field
(Jaenson et al., 2006).
However, plants whose essential
oils have been
reported to have repellent activity include citronella,
cedar, verbena, pennyroyal, geranium, lavender, pine,
cinnamon, rosemary, basil, thyme, and peppermint.
Most of these essential oils provided short-lasting
usually lasting less than 2 h. Many essential
oils and their monoterpenic constituents are known
for their mosquito repellent activity against Culex
species (Choi et al., 2002; Traboulsi et al., 2002).
The mosquito repellent activity of 38 essential oils
was screened against the mosquito A. aegypti under
laboratory conditions using human subjects
(Trongtokit et al., 2005). The oils of Cymbopogon
nardus (citronella), Pogostemon cablin (patchuli),
Syzygium aromaticum (clove) and Zanthoxylum
limonella were the most effective and provided 2 h
of complete repellency. Among three essential oil
constituents namely eugenol, cineole and citronellal,
the later was found to be most effective against A.
aegypti mosquito (Coats et al., 1991). Lemon grass
oil ointment containing 15% v/w citral exhibited 50%
repellency which lasted for 2–3 h (Oyedela et
al., 2002). It has now been reported that a component
of the essential oil of the catnip plant (Nepeta
cateria), the nepetalactone repels mosquitoes 10
times more effectively than DEET as it takes about
one-tenth as much nepetalactone as DEET to have
the same effect. Tagetes erecta is a potential plant
whose essential oil from flowers has been effective
repellent against insects (Ray et al., 2000).
Accordingly ocimene from T. minuta has also
repellent properties which need to be exploited in
Cinnamaldehyde, eugenol, cinnamyl acetate and
essential oils from different Cinnamomum species
are effective mosquito larvicides (Huang and Ho,
1998; Cheng et al., 2004). Several monoterpenoidal
constituents evaluated for their insect repellent
activity show that linalool and nerol in linear
monoterpenoids and carvone, pulegol, pulegone and
isopulegol in monocyclic monoterpenoids are the
most effective space repellents; some others have
been found effective as repellents against the German
cockroach, B. germanica (Inazuka, 1983). Two
monoterpenes namely menthol and citral have been
reported to be toxic against tracheal mites (Ellis and
Baxendale, 1997). Thus such essential oil compounds
may play a pivotal role in the control of mosquito
driven dengue and malaria outbreaks through lure
and kill technique. In recent years, several
monoterpenoids have been considered potential
alternatives to conventional insecticides as a natural
means of pest control. Since oxygenated essential
oil constituents are more active, efforts have been
made to improve bioefficacy of one such oxygenated
essential oil constituent fenchone (LC
= 3.8 mg/l
for house flies and 14.2 mg/l for red flour beetles;
Rice and Coats, 1994) by its chemical modification
and structure-activity relationship studies.
Turmerone and ar-turmerone (dehyd-
roturmerone), the major constituents of turmeric
rhizome powder oil are strong repellents to stored
grain pests. The turmeric oil has been reported to
provide protection to wheat grains against red flour
beetle, T. castaneum (Herbst) (Chahal et al., 2005).
The fruit oil of Piper retrofractum has also shown
high repellency (52–90%) against T. castaneum at
0.5–2% concentration.
Oviposition Inhibitors and Ovicides
Application of 1, 8 cineole and majoram reduced
ovipopsition rate by 30–50% at concentration of
1.0%, as compared to untreated controls (Koshier
and Sedy, 2001). In Egypt, A. calamus oil at 0.1%
prevented oviposition of C. maculatus (Dimetry et
2008 Koul et al. : Essential oils as green pesiticides 75
al., 2003). Garlic oil which is also an oviposition
deterrent has been found to be highly toxic to eggs
of P. xylostella (Govindaraddi, 2005) and 99.5%
reduction in egg hatching has been recorded in S.
obliqua at 250 mg oil/50 eggs using essential oil of
Aegle marmelos (Tripathi et al., 2003). l-Carvone
also completely suppresses the egg hatching of T.
castaneum at 7.22 mg/cm
surface treatment (Tripathi
et al., 2003). Carvacrol, carveol, geraniol, linalool,
menthol, terpineol, thymol, verbenol, carvones,
fenchone, menthone, pulegone, thujone, verbenone,
cinnamaldehyde, citral, citronellal, and cinnamic acid
have been evaluated as ovicides against M. domestica
eggs (Rice and Coats, 1994). Inhibition of hatching
ranged from 33–100%. These studies demonstrate
that monoterpenoid ketones are significantly more
effective than structurally similar alcohols (like
menthone versus menthol; verbenone versus
verbenol, etc.)
Geraniol and eugenol are effective attractants
and are used as lures in traps for the Japanese beetle,
Popillia japonica Newman, and methyl-eugenol has
been used to trap oriental fruit fly, Dacus dorsalis
Hendel (Vargas et al., 2000). Cinnamyl alcohol, 4-
methoxy-cinnamaldehyde, cinnamaldehyde, gerany-
lacetone and α-terpineol are also attractive to adult
corn rootworm beetles, Diabrotica sp. (Hammack,
1996; Petroski and Hammack, 1998). The essential
oil and a number of extracts of Rosmarinus officinalis
L. in solvents of increasing polarity have been iso-
lated, and their components identified and tested as
pest control agents. Ethanol and acetone extracts
attract grape berry moth, Lobesia botrana. How-
ever, none of the extracts had a significant effect on
western flower thrips, Frankliniella occidentalis,
which is attracted by 1,8-cineole, a major essential
oil component (Katerinopoulos et al., 2005).
Lemon essential oil is distilled from the peels
of Citrus limonum. It has a light yellow color and a
characteristic lemon aroma. Lemon essential oil
contains several terpenes and geraniol, which have
all been shown to attract thrips, fungus gnats,
mealybugs, scale, and Japanese beetles. Adding this
oil to the insect-a-peel, thrips/leafminer blue trap, or
the yellow aphid/whitefly sticky trap will attract these
unwanted pests and capture them on the trap (http://
Compositions of cis-jasmone were found to
effectively attract adult Lepidoptera. The cis-jasmone
may be used alone or in combination with one or
more other volatiles of the Japanese honeysuckle
flower, particularly linalool and/or phenylac-
etaldehyde. By attracting the adult Lepidoptera to
attracticidal baits and/or field traps, the attractants
are useful for the control and monitoring of these
agricultural pests (Pair and Horvat, 1997). Similarly,
natural essential oils have shown a high attractiveness
for greenhouse whitefly, Trialeurodes vaporariorum
Westwood. Greenhouse whitefly reacted particularly
intensively to sandalwood oil, basil oil, and grapefruit
oil. After the application of aromatic substances on
yellow sticky traps, the number of insects caught
increased significantly amounting to 487.64, 483.20,
and 333.09%, respectively (Górski, 2004). Thus,
natural essential oils or their constituents could be
useful in the monitoring of pests, at least greenhouse
whitefly in the present case.
Antifungal Agents
Antifungal activities of certain essential oils or
their components have also been assessed and found
effective for Botrytis cinerea (Wilson et al., 1997),
Monilinia fructicola (Taso and Zhou, 2000),
Rhizoctonia solani, Fusarium moniliforme and
Sclerotinia sclerotiorum (Muller et al., 1995), F.
oxysporum (Bowers and Locke, 2000), Cymbopogon
nardus (De-Billerbeck et al., 2001), Aspergillus niger
(Paster et al., 1995), A. flavus (Montser and Carvajal,
1998), Penicillium digitatum (Daferera et al., 2000)
and F. solani, R. solani, Pythium ultimum and
Colletotrichum lindemuthianum (Zambonelli et al.,
1996), Alternaria padwickii, Bipolaris oryzae, and
peanut fungi (Nguefack et al., 2007; Krishna and
Pande, 2007). Unlike insects, different fungal species
show more consistent results. Thymol and carvacrol
are definitely active against most fungal species tested
(Kurita et al., 1981; Muller-Riebau et al., 1995; Tsao
and Zhou, 2000). The mechanism of action of these
compounds against fungi is unknown but may be
related to their general ability to dissolve or otherwise
76 Biopesticides International Vol. 4, no. 1
disrupt the integrity of cell walls and membranes
(Isman and Machial, 2006).
Greenhouse experiments have been conducted
to determine the effectiveness of plant essential oils
as soil fumigants to manage bacterial wilt (caused
by Ralstonia solanacearum) in tomato. Pottin-
gmixture (“soil”) infested with R. solanacearum was
treated with the essential oils at 400 mg and 700 mg
per liter of soil in greenhouse experiments. R.
solanacearum population densities were determined
just before and 7 days after treatment. Populations
declined to undetectable levels in thymol, palmarosa
oil, and lemongrass oil treatments at both concentra-
tions, whereas tea tree oil had no effect. Tomato
seedlings transplanted in soil treated with 700 mg/
liter of thymol, 700 ml/liter of palmarosa oil, and
700 ml/liter of lemongrass oil were free from bacte-
rial wilt and 100% of plants in thymol treatments
were free of R. solanacearum (Pradhanang et al.,
Antiviral Agents
The plant volatile oils and pure isolates have
been mentioned as containing substances which in-
terfere with or inhibit infection of viruses. The es-
sential oil of Melaleuca alternifolia in concentration
of 100, 250, 500 ppm has been found to be effective
in decreasing local lesions of TMV on host plant
Nicotiana glutinosa (Bishop, 1995). Similarly, es-
sential oils of Ageratum conyzoides, Callistemon
lanceolatus, Carum copticum, Ocimum sanctum and
Peperomia pellucida have been evaluated for in-
hibitory activity against cowpea mosaic virus
(CPMV), mung bean mosaic virus (MBMV), bean
commonil mosaic virus (BCMV) and southern bean
mosaic virus (SBMV). Ocimum sanctum at 3000
ppm gave the best inhibition of 89.6, 90, 92.7, 88.2%
against CMV, MBMV, BCMV, and SBMV respec-
tively. The other oils also showed inhibitory activity
against other viruses (Rao et al., 1986) Another re-
port has shown 62% inhibition against tobacco mo-
saic virus. The fresh hydrodistilled carrot leaves
yielded 0.07% essential oil, analysed by GLC and
TLC. Constituents were identified by IR, NMR and
mass spectra. Twenty nine compounds were identi-
fied and the major constituents were Sabinene
(10.93%), linalool (14.90%), linalyl acetate (8.35%),
and Carvone (8.77%) (Khanna et al., 1990)
Tagetes minuta oil has been found to be active
against carnation ring spot (CaRSV) and carnation
vein mottle viruses (CaVMV). The ingredients
present in the oil namely dihydrotagetone and
ocimene when tested individually in pure form, were
found to have enhanced antiviral activity against two
carnation viruses (US Patent 6444458, 2002). The
oil as such and the bioactive consitituent present in
oil can be commercially used as natural and eco-
friendly antiviral products.
Thrips-vectored Tomato spotted wilt virus is one
of the most devastating pest complexes affecting to-
mato. Field trials were conducted over 2 years to
determine the effects of volatile plant essential oils
and kaolin-based particle films on the incidence of
tomato spotted wilt and population dynamics of
Frankliniella thrips. The essential oils compound,
geraniol, lemongrass (Cymbopogon flexuosus) oil,
and tea tree (Melaleuca alternifolii) oil, were com-
pared with a standard insecticide treatment and an
untreated control. All treatments were applied with
and without kaolin, in a 5 × 2 factorial design. When
combined with kaolin, the three essential oils re-
duced tomato spotted wilt virus incidence by 32 to
51% in 2005 and by 6 to 25% in 2006 compared
with the control. When applied with kaolin, the three
essential oils produced yields similar to the insecti-
cide standard (Reitz et al., 2008). Therefore, natu-
rally occurring products, such as essential oils and
kaolin, could be used successfully to control viruses
and reduce insecticide use on tomatoes.
In spite of considerable research effort in many
laboratories throughout the world and an ever-
increasing volume of scientific literature on the
pesticidal properties of essential oils and their
constituents, surprisingly few pest control products
based on plant essential oils have appeared in the
market place. This may be a consequence of
regulatory barriers to commercialization (i.e. cost of
toxicological and environmental evaluations) or the
fact that efficacy of essential oils toward pests and
2008 Koul et al. : Essential oils as green pesiticides 77
diseases is not as apparent or obvious as that seen
with currently available products. In the United
States, commercial development of insecticides based
on plant essential oils has been greatly facilitated by
exemption from registration for certain oils
commonly used in processed foods and beverages
(Quarels, 1996). This opportunity has spurred the
development of essential oil-based insecticides,
fungicides, and herbicides for agricultural and
industrial applications and for the consumer market,
using rosemary oil, clove oil, and thyme oil as active
ingredients. Interest in these products has been
considerable, particularly for control of greenhouse
pests and diseases and for control of domestic and
veterinary pests. Nonetheless, some U.S. companies
have introduced essential-oil-based pesticides in
recent years. Mycotech Corporation produced an
aphidicide/miticide/fungicide for greenhouse and
horticultural use and for bush and tree fruits based
on cinnamon oil with cinnamaldehyde (30% in the
EC formulation) as the active ingredient, however,
this product is no longer being sold. EcoSMART
Technologies has introduced insecticides containing
eugenol and 2-phenethyl propionate aimed at
controlling crawling and flying insects, under the
brand name EcoPCO
for pest control professionals.
An insecticide/miticide containing rosemary oil as
the active ingredient has recently been introduced
for use on horticultural crops under the name
. Another product based on rosemary oil
is a fungicide sold under the name Sporan
, while
a formulation of clove oil (major constituent:
eugenol), sold as Matran
, is used for weed control.
All of these products have been approved for use in
organic food production. The primary active
ingredients in EcoSMART products are exempt from
Environmental Protection Agency registration and
are approved as direct food additives or classifies as
GRAS (generally recognized as safe) by the Food
and Drug Administration.
Several smaller companies in the U.S. and the
U.K. have developed garlic-oil based pest control
products and in the U.S. there are consumer
insecticides for home and garden use containing mint
oil as the active ingredient. Menthol has been
approved for use in North America for control of
tracheal mites in beehives, and a product produced
in Italy (Apilife VAR
) containing thymol and lesser
amounts of cineole, menthol and camphor is used to
control Varroa mites in honeybees (Canadian Honey
The humble marigold could be the key to
organic, renewable and cost-effective pest control,
according to researchers at De Montfort University
(DMU) in Leicester. Tagetes patula, the French
marigold species most common to gardens, has the
ability to destroy attackers beneath the soil and it is
this property that researchers believe could be
harnessed to help protect crops.
Israel startup Botanocap, founded on oil
encapsulation knowledge created at the Ben Gurion
University of the Negev, is developing a slow release
technology for essential oils, to make relatively
environmentally friendly pesticides. The company
has developed a patented technology for the gradual
release of essential etheric oils and natural
components. It possesses patents on capturing
essential oils in capsules, to achieve the delayed
release effect. Etheric oils can be produced from
some 3000 plants. Controlled slow release with
protecting the active components until release are
the main point of Botanocap (http://www.ivc-online/
In terms of green pesticide technology using
oil-in-water microemulsions as a nano-pesticide
delivery system to replace the traditional
emulsifiable concentrates (oil), in order to reduce
the use of organic solvent and increase the
dispersity, wettability and penetration properties of
the droplets is being developed. The advantages
of using pesticide oil-in-water microemulsions for
improving the biological efficacy and reducing the
dosage of pesticides would be a useful strategy in
green pesticide technology.
Pesticides based on plant essential oils or their
constituents have demonstrated efficacy against a
range of stored product pests, domestic pests, blood-
78 Biopesticides International Vol. 4, no. 1
feeding pests and certain soft-bodied agricultural
pests, as well as against some plant pathogenic
fungi responsible for pre- and post-harvest diseases.
They may be applied as fumigants, granular
formulations or direct sprays with a range of effects
from lethal toxicity to repellence and/or oviposition
deterrence in insects. These features indicate that
pesticides based on plant essential oils could be
used in a variety of ways to control a large number
of pests.
In terms of specific constraints, the efficacy of
these materials falls short when compared to synthetic
pesticides although there are specific pest contexts
where control equivalent to that with conventional
products has been observed. Essential oils also
require somewhat greater application rates (as high
as 1% active ingredient) and may require frequent
reapplication when used out-of-doors.
Additional challenges to the commercial
application of plant essential-oil-based pesticides
include availability of sufficient quantities of plant
material, standardization and refinement of pesticide
products, protection of technology (patents) and
regulatory approval (Isman, 2005). Although many
essential oils may be abundant and available year
round due to their use in the perfume, food and
beverage industries, large-scale commercial
application of essential-oil-based pesticides could
require greater production of certain oils. In addition,
as the chemical profile of plant species can vary
naturally depending on geographic, genetic, climatic,
annual or seasonal factors, pesticide manufacturers
must take additional steps to ensure that their
products will perform consistently. All of this requires
substantial cost and smaller companies may not be
willing to invest the required funds unless there is
a high probability of recovering the costs through
some form of market exclusivity (e.g. patent
protection). Finally, once all of these issues are
addressed, regulatory approval is required. Although
several plant essential oils are exempt from
registration in the United States, many more oils
are not, and few countries currently have such
exemption lists. Accordingly, regulatory approval
continues to be a barrier to commercialization and
will likely continue to be a barrier until regulatory
systems are adjusted to better accommodate these
products (Isman and Machial, 2006).
In fact, pesticides derived from plant essential
oils do have several important benefits. Due to their
volatile nature, there is a much lower level of risk to
the environment than with current synthetic
pesticides. Predator, parasitoid and pollinator insect
populations will be less impacted because of the
minimal residual activity, making essential-oil-based
pesticides compatible with integrated pest
management programs. It is also obvious that
resistance will develop more slowly to essential-oil-
based pesticides owing to the complex mixtures of
constituents that characterize many of these oils.
Ultimately, it is in developing countries where the
source plants are endemic that these pesticides may
ultimately have their greatest impact in integrated
pest management strategy. It is expected that these
pesticides will find their greatest commercial
application in urban pest control, public health,
veterinary health, vector control vis-à-vis human
health and in protection of stored commodities. In
agriculture, these pesticides will be most useful for
protected crops (e.g. greenhouse crops), high-value
row crops and within organic food production
systems where few alternative pesticides are avail-
able. There are thus the opportunities like (i)
changing consumer preferences towards the use of
‘natural’ over synthetic products; (ii) existence of
and growth in niche markets, where quality is more
important than price; (iii) strong growth in demand
for essential oils and plant extracts; (iv) potential to
extend the range of available products including new
product development through biotechnology; (v)
production of essential oils and plant extracts from
low cost developing countries.
Acknowledgements. Authors are thankful to
Gurmeet Singh, Rajwinder Singh and Anshu Middha
for rendering suitable help during the compilation of
this review. This review article contains information
gathered from numerous published resources, and thus
we would like to extend our appreciation to all authors
of the references used in this manuscript.
2008 Koul et al. : Essential oils as green pesiticides 79
Agarwal, M. and Walia, S. (2003) Pest control potential
of phytochemicals derived from Curcuma longa
and Zingiber officinale. In P. Dureja, D.B. Saxena,
J. Kumar, S.B. Singh, M. Gopal and R.S. Tanwar
(eds.), Proc. Int. Conf. Pesticides, Environment,
Food Security, Society of Pesticide Science, New
Delhi, pp 110–119.
Agarwal, M., Walia, S. and Dhingra, S. (1999) Pest
control properties of turmeric leaf oil against
Spilosoma obliqua, Dysdercus koenigii and Trib-
olium castaneum. Proceed. 2
All India People’s
Congress, Calcutta, pp l–7.
Agarwal, M., Walia, S. and Dhingra, S. (2000) Insect
growth inhibition, antifeedant and antifungal
activity of compounds isolated/derived from
Zingiber officinale rhizomes. Pest Manag. Sci.,
37, 289–300.
Beninger, C.W., Ndyiragije, P. and Arnason, J.T. (1993)
Diterpene 3-epicaryoptin affects growth and
development of the European corn borer (Lepid-
optera: Pyrallidae). J. Econ. Entomol., 86, 1559–
Bhatnagar, M., Kapur, K.K., Jalees, S. and Sharma,
S.K. (1993) Laboratory evaluation of insecticidal
properties of Ocimum basilicum Linnaeus and O.
sanctum Linnaeus plant’s essential oils and their
major constituents against vector mosquito species.
Entomol. Res., 17, 21–29.
Bischof, L.J. and Enan, E.E. (2004) Cloning, expression
and functional analysis of an octopamine receptor
from Periplaneta americana. Insect Biochem. Mol.
Biol., 34, 511–521.
Bishop, C.D. (1995) Antiviral activity of the essential
oil of Melaleuca alternifolia (Maiden & Betche)
cheel (Teatree) against Tobacco Mosaic Virus. J.
Essen. Oil Res., 7, 641–648.
Bowers, J.H. and Locke, L.C. (2000) Effect of botanical
extracts on the population density of Fusarium
oxisporum in soil and control of Fusarium wilt in
the green house. Plant Dis., 84, 300–305.
Calderone, N.W. and Spivak, M. (1995) Plants extracts
for control of the parasite mite Varroa jacobsoni
(Acari:Varroidae) in colonies of the western honey
bee (Hymenoptera: Apidae). J. Econ. Entomol.,
88, 1211–1215.
Carroll, J.F. (1994) Feeding deterrence in northern fowl
mites (Acari: Macronyssidae) by some naturally
occurring plant substances. Pestic. Sci., 41, 203–
Chahal, K.K., Arora, M., Joia, B.S. and Chhabra, B.R.
(2005) Bioefficacy of turmeric oil against
Tribolium castaneum (Herbst) under laboratory
conditions. In V.K. Dilawari, G.S. Deol, B.S. Joia
and P.K. Chuneja (eds.), Proc. 1
Congress on
Insect Science: Contributed Papers, PAU
Ludhiana, pp. 147–148.
Chang, K.S. and Ahn, Y.T. (2001) Fumigant activity of
(E) - anethole identified in Illicium verum fruit
against Blattella germanica. Pest Manage. Sci.,
58, 161–166.
Chang, S.T. and Cheng, S.S. (2002) Antitermitic activity
of leaf essential oils and components from
Cinnamomum osmophleum. J. Agric. Food Chem.,
50, 1389–1392.
Chauhan, K.R. and Raina, A.K. (2006) Effect of catnip
oil and its major compounds on the formosan
subterranean termite (Coptotermes formosanus).
Biopestic. Int., 2, 137–143.
Cheng, S.S., Liu, J.Y., Tsai, K.H., Chen, W.J. and
Chang, S.T. (2004) Chemical composition and
mosquito larvicidal activity of essential oils from
leaves of different Cinnomomum osmophloeum
provenances. J. Agric. Food Chem., 52, 4395–
Chiasson, H., Belanger, A., Bostanian, N., Vincent, C.
and Poliquin, A. (2001) Acaricidal properties of
Artemisia absinthium and Tanacetum vulgare
(Asteraceae) essential oils obtained by three
methods of extractions. J. Econ. Entomol., 94,
Choi, W.I., Lee, S.G., Park, H.M. and Ahn, Y.J. (2004)
Toxicity of plant essential oils to Trialeuroides
vaporariorum (Homoptera:Aleyrodidae). J. Econ.
Entomol., 96, 1479–1484.
Choi, W.S., Park, B.S., Ku, S.K. and Lee, S.K. (2002)
Repellent activities of essential oils and mono-
terpenes against Culex pipiens. J. Am. Mosq.
Cont. Assoc., 18, 348–351.
Chowdhury, H., Singh, R.D., Mandal, P. and Dutta, A.
(2000) Antifeedant activity of two essential oils
on lepidopteran insects. Pestic. Res. J., 12, 137–
Coats, J.R., Karr, L.L. and Drewes C.D. (1991) Toxicity
and neurotoxic effects of monoterpenoids in insects
80 Biopesticides International Vol. 4, no. 1
and earthworms. In P. A. Hedin (ed.), Naturally
Occurring Pest Bioregulators, ACS Symposium
Series 449, American Chemical Society, Wash-
ington DC, pp. 306–316.
Cockcroft, A., Cosgrove, J.B. and Wood, R.J. (1998)
Comparative repellency of commercial formulation
of deet, permethrin and citronellal against the
mosquito Aedes aegypti, using a collagen memb-
rane technique compared with human arm tests.
Med. Vet. Entomol., 12, 289–294.
Cornelius, M.L., Grace, J.K. and Yates III, J.R. (1997)
Toxicity of monoterpenoids and other natural
products to the Formosan subterranean termite
(Isoptera: Rhinotermitidae). J. Econ. Entomol., 90,
Daferera, D.J., Ziogas, B.N. and Polissiou, M.G. (2000)
GC-MS analysis of essential oils from some Greek
aromatic plants and their fungi toxicity on
Penicillium digitatum. J. Agric. Food Chem., 48,
Dhaliwal, G.S. and Koul, O. (2007) Biopesticides and
Pest Management: Conventional and Biotech-
nological Approaches. Kalyani Publishers, New
De-Billerbeck, V.G., Roques, C.G., Bessiere, J.M.,
Fonvieille, J.L. and Dargent, R. (2001) Effects of
Cymbopogon nardus (L) essential oil on the growth
and morphogenesis of Aspergillus niger. Can. J.
Microbiol., 47, 9–17.
Dev, S. and Koul, O. (1997) Insecticides of Natural
Origin. Harwood Academic Publishers, Amster-
dam, Netherlands.
Dietrich, G., Dolan, M.C., Peralta-Cruz, J., Schmidt,
J., Piesman, J., Eisen, R.J. and Karchesy, J.J. (2006)
Repellent activity of fractioned compounds from
Chamaecyparis nootkatensis essential oil against
nymphal Ixodes scapularis (Acari: Ixodidae). J.
Med. Entomol., 43, 957–961.
Dimetry, N.Z., Hafez, M. and Abbass, M.H. (2003)
Efficiency of some oils and neem formulations
against the cow pea beetle, Callosobruchus
maculatus (Fabricius) Coleoptera: Bruchidae). In
O. Koul, G.S. Dhaliwal, S.S. Marwaha and J. K.
Arora (eds.), Biopesticides and Pest Management,
Vol. 2, Campus Books International, New Delhi,
pp. 1–10.
Don-Pedro, K.M. (1996) Investigation of single and
joint fumigant insecticidal action of citrus peel oil
components. Pestic. Sci., 46, 79–84.
Dubey, A., Gupta, R. and Chandel, B.S. (2004) Efficacy
af Acorus calamus, Vitex negundo and Ageratum
conyzoides against tobacco caterpillar, Spilarctia
obliqua Walker. Indian J. Entomol., 66, 238–240.
Ellis, M.D. and Baxendale, F.P. (1997) Toxicity of seven
monoterpenoids to tracheal mites (Acari: Tarson-
emidae) and their honey bee (Hymenoptera:
Apidae) hosts when applied as fumigants. J. Econ.
Entomol., 90, 1087–1091.
FAO (1999) The use of spices and medicinals as
bioactive protectants for grains. Agriculture Service
Bulletin, 137, 201–213.
Franzios, G., Mirotsou, M., Hatziapostolou, E., Kral,
J., Scouras, Z.G. and Mauragani-Tsipidou, P.
(1997) Insecticidal and genotoxic activities of mint
essential oils. J. Agric. Food Chem., 45, 2690–
Górski, R. (2004) Effectiveness of natural essential
oils in the monitoring of greenhouse whitefly (Tri-
aleurodes vaporariorum Westwood). Folia Hort.,
16, 183–187.
Govindaraddi, K. (2005) Antifeedant and insecticidal
properties of essential oils of turmeric (Curcuma
longa L.) and garlic (Allium sativum L.) against
diamond back moth, Plutella xylostella (L). M.Sc
thesis,CCS Haryana Agricultural University, Hisar.
Gunderson, C.A., Samuelian, J.H., Evans, C.K. and
Bratisten, L. (1985) Effects of the mint monoter-
pene pulegone on Spodoptera eridania (Lepido-
ptera: Noctuidae). Environ.Entomol., 14, 859–863.
Hammack, L. (1996) Corn volatiles as attractants for
northern and western corn rootworm beetles (Cole-
opteran: Chrysomelidae: Diabrotica sp.). J. Chem.
Ecol., 22, 1237–1253.
Harwood, S.H., Modenke, A.F. and Berry, R.E. (1990)
Toxicity of peppermint monoterpenes to the
variegated cutworm (Lepidoptera: Noctuidae). J.
Econ. Entomol., 83, 1761–1767.
Hierro, I., Valero, A., Perez, P., Gonzalex, P., Cabo,
M.M. and Navarro, M.C. (2004) Action of
different monoterpenic compounds against
Anisakis simplex S.l.L
larvae. Phytomedicine, 11,
Huang, Y. and Ho, S.H. (1998) Toxicity and antifeedant
activities of cinnamaldehyde against the grain
storage insects Tribolium castaneum (Herst) and
Sitophillus zeamais Motsch. J. Stored Prod. Res.,
2008 Koul et al. : Essential oils as green pesiticides 81
34, 11–17.
Hummelbrunner, A. L. and Isman, M.B. (2001) Acute,
sublethal, antifeedant and synergistic effects of
monoterpenoid essential oil compounds on the
tobacco cut worm (Lepidoptera: Noctuidae). J.
Agric. Food Chem., 49, 715–720.
Inazuka, S. (1983) Monoterpenoids as repellents against
the German cockroach (Blattela germanica L.). J.
Pestic. Sci., 8, 293–299.
Isman, M.B. (2000) Plant essential oils for pest and
disease management. Crop Prot., 19, 603–608.
Isman, M.B. (2005) Problems and opportunities for
the commercialization of botanical insecticides.
In C. Regnault-Roger, B.J.R. Philog‘ene and C.
Vincent (eds.), Biopesticides of Plant Origin,
Lavoisier, Paris, pp. 283–291.
Isman, M.B. and Machial, C.M. (2006) Pesticides based
on plant essential oils: from traditional practice to
commercialization. In M. Rai and M.C. Carpinella
(eds.), Naturally Occurring Bioactive Compounds,
Elsevier, BV, pp 29–44
Jacobson, M. and Halber, L. (1947) The Chemistry of
Organic Medicinal Plants, Chapman and Hall,
New York.
Jaenson, T.G.T., Garboul, S. and Pålsson, K. (2006)
Repellency of oils of lemon, eucalyptus, geranium,
and lavender and the mosquito repellent MyggA
natural to Ixodes ricinus (Acari: Ixodidae) in the
laboratory and field. J. Med. Entomol., 43, 731–
Karr, L.L. and J.R. Coats (1988). Insecticidal properties
of d- limonene. J. Pestic. Sci., 13, 2287–2290.
Karr, L.L. and Coats, J.R. (1992) Effects of four
monoterpenoids on growth and reproduction of
the German cockroach (Blattodea: Blattellidae).
J. Econ. Entomol., 85, 424–429.
Katerinopoulos, H., Pagona, G, Afratis, A., Stratigakis,
N. and Roditakis, N. (2005) Composition and
insect attracting activity of the essential oil of
Rosmarinus officinalis. J. Chem Ecol., 31, 111-
Khanna, R.K., Sharma, O.S., Singh, A., Battacharya,
S.C., Sen, N. and Sethi, K.L. (1990) The essential
oil from leaves of Dacus carota Linn. var sativa.
Chem. Anal. Struc., 14, 173–176.
Klocke, J.A., Balandrin, M.F. and Yamasaki, R.B.
(1989) Limonoids, phenolics and furano-coumarins
as insect antifeedants, repellants and growth
inhibitory components. In J.T. Arnason, P. Morand
and B.J.R. Philogene (eds.), Insecticides of Plant
Origin, American Chemical Society, Washington
DC, pp. 136–149.
Kordali, S., Cakir, A., Mavi, A., Kilic, H. and Yildirim,
A. (2005) Screening of chemical composition and
antifungal activity of essential oils from three
Turkish Artemisia species. J. Agric. Food Chem.,
53, 1408–1416.
Kostyukovsky, M., Rafaeli, A., Gileadi, C., Demchenko,
N. and Shaaya, E. (2002) Activation of octopa-
minergic receptors by essential oil constituents
isolated from aromatic plants: possible mode of
action against insect pests. Pest Manag. Sci., 58,
Koschier, E.L. and Sedy, K.A. (2001) Effects of plant
volatiles on the feeding and oviposition of Thrips
tabaci. In R. Marullo and L. Mound (eds.), Thrips
and Tospoviruses, CSIRO, Australia, pp. 185–187.
Koul, O. (1995) Acorus allelochemical: Chemistry and
bioefficacy against insects. In B.S. Parmar and S.
Walia (eds.), Pesticides, Crop Protection and
Environment, Oxford and IBH Publishing Co. Pvt.
Ltd., New Delhi, pp. 99–113.
Koul, O. (2005) Insect Antifeedants. CRC Press, Bota
Racon, FL.
Koul, O. (2008) Phytochemicals and insect control:
An antifeedant approach. Crit. Rev. Plant Sci., 27,
Koul O, Smirle MJ and Isman MB (1990). Asarones
from Acorus calamus L. oil, their effect on
feeding behavior and dietary utilization in
Peridroma saucia. J. Chem. Ecol. 16: 1911–1920.
Koul, O., Dhaliwal, G.S. , Marwaha, S.S. and Arora,
J.K. (2003) Future perspectives in biopesticides.
In O. Koul, G.S. Dhaliwal, S.S. Marwaha and J.K
Arora (eds.), Biopesticides and Pest Management.,
Vol.1, Campus Books International, New Delhi,
pp. 386–388.
Koul, O., Singh, G., Singh, R. and Singh, J. (2007)
Mortality and reproductive performance of
Tribolium castaneum exposed to anethole vapours
at high temperature. Biopestic. Int., 3, 126–137.
Krishna Kishore, G., Pande, S. and Harsha, S. (2007)
Evaluation of essential oils and their components
for broad-spectrum antifungal activity and control
of late leaf spot and crown rot diseases in peanut.
Plant Dis., 91, 375–379.
82 Biopesticides International Vol. 4, no. 1
Kurita, N., Miyaji, M., Kurane, R. and Trakahara, Y.
(1981) Antifungal activity of components of
essential oils. Agric. Biol. Chem., 45, 945–952.
Lawerence, B.M. and Reynolds, R.J. (2001) Progress
in essential oils. Perf. Flavour., 26, 44–52.
Lee, B.H., Choi, W.S., Lee, S.E. and Park, B.S. (2001)
Fumigant toxicity of essential oils and their
constituent compounds towards the rice weevil,
Sitophilus oryzae (L.). Crop Prot., 20, 317–320.
Lee, S., Tsao, R. and Coats, J.R. (1999). Influence of
dietary applied monoterpenoids and derivatives on
survival and growth of the European corn borer
(Lepidoptera: Pyrallidae). J. Econ. Enomol., 92,
Lee, S., Tsao, R., Peterson, C. and Coats, J.R. (1997)
Insecticidal activity of monoterpenoids to western
corn root worm (Coleoptera: Chrysomelidae), two
spotted spidermite (Acari: Tetranychidae) and
Housefly (Diptera: Muscidae). J. Econ. Entomol.,
90, 883–892.
Lichtenstien, E.P., Liang, T.T., Shulz, K.R., Schnoes,
H.K. and Carter, G.T. (1974). Insecticide and syner-
gistic components isolated from dill plant. J. Agric.
Food Chem., 22, 658–664.
Marcus, C. and Lichtenstein, E.P. (1979) Biologically
active components of anise toxicity and inter-
actions with insecticides in insects. J. Agric. Food
Chem., 27, 1217–1223.
Meepagala, K.M., Osbrink, W., Sturtz, G. and Lax, A.
(2006) Plant derived natural products exhibiting
activity against formosan subterranean termites
(Coptotermes formosanus). Pest Manag. Sci., 62,
Miresmailli, S., Bradbury, R. and Isman, M.B. (2006)
Comparative toxicity of Rosmarinus officinalis L.
essential oil blends of its major constituents against
Tetranychus urticae Koch (Acari: Tetranychidae)
on two different host plants. Pest Manag. Sci.,
62, 366–371.
Montser, B.R. and Carvajal, M. (1998) Control of
Aspergillus flavus in maize with plant essential
oils and their components. J. Food Prot., 61, 616–
Muller, R.F., Berger, B. and Yegen, O. (1995) Chemical
composition and fungi toxic properties to phyto
pathogenic fungi of essential oils of selected
aromatic plants growing wild in Turkey. J. Agric.
Food Chem., 43, 2262–2266.
Ngoh, S.P., Cho, L.E.W., Pang, F.Y., Huang, Y., Kini,
M.R. and Ho, S.H. (1998) Insecticidal and repellent
properties of nine volatile constituents of essential
oils against the American cockroach, Periplanata
americana (L.). Pestic. Sci., 54, 261–268.
Nguefack, J., Nguikwie, S.K., Fotio, D., Dongmo, B.,
Zollo, P.H. Amvam, Leth, V., Nkengfack, A.E.,
Poll, L. (2007). Fungicidal potential of essential
oils and fractions from Cymbopogon citratus,
Ocimum gratissimum and Thymus vulgaris to
control Alternaria padwickii and Bipolaris oryzae,
two seed-borne fungi of rice (Oryza Sativa L). J.
Essen. Oil Res., 19, 581–587.
Ning, J., Kong, F., Lin B. and Lei, H. (2003) Large-
scale preparation of the phytoalexin elicitor
glucohexatose and its application as a green
pesticide. J. Agric. Food Chem., 51, 987–991.
Obeng-Ofori, D. and Reichmuth, C.H. (1997)
Bioactivity of eugenol, a major component of
essential oil of Ocimum suvae (wild) against four
species of stored product coleopteran. Int. J. Pest
Manag., 43, 89–94.
Ouden, H.D., Visser, J.H., Alkena, D.P.W., Dei, J.J.
and Derk, P.S.M. (1993). Experiments with volatile
substances in slow release formulations causing
repellency for oviposition by the cabbage root fly,
Phorbia brassicae (Diptera : Anthomydae). J.
Appl. Entomol., 115, 307–312.
Oyedela, A.O., Gbolade, A.A., Sosan, M.B.,
Adewoyin, F.B., Soyely, O.L. and Orafidiya, O.O.
(2002). Formulation of an effective mosquito
repellent topical product from lemon grass oil.
Phytomedicine, 9, 259–262.
Pair, S.D. and Horvat, R.J. (1997) Volatiles of Japanese
honeysuckle flowers as attractants for adult
Lepidopteran insects. US Patent 5665344.
Paster, N., Menasherou, M., Ravid, U. and Juven, B.
(1995) Antifungal activity of oregano and thyme
essential oils applied as fumigants against fungi
attacking stored grain. J. Food Protect., 58, 81–
Perrucci, S. (1995) Acaricidal activity of some essential
oils and their constituents against Tyrophagus
longior, a mite of stored food. J. Food Prot., 58,
Perrucci, S., Macchioni, G., Gioni, P.L., Flamini, G.
and Morelli, I. (1995) Structure toxicity relation-
ship of some natural monoterpenes as acaricides
2008 Koul et al. : Essential oils as green pesiticides 83
against Psoroptes cuniculi. J. Nat. Prod., 58,
Panella, N.A., Dolan, M.C., Karchesy, J.J., Xiong, Y.,
Peralta-cruz, J., Mohammad Khasawneh, M.,
Montenieri, J.A. and Maupin, G.O. (2005) Use of
novel compounds for pest control: Insecticidal and
acaricidal activity of essential oil components from
heartwood of alaska yellow cedar. J. Med.
Entomol., 42, 352–358.
Paruch, E., Ciunik, Z., Nawrot, J. and Wawrzenczyk,
C. (2000) Lactones: Synthesis of terpenoids
lactones active insect antifeedants. J. Agric. Food
Chem., 48, 4973–4977
Petroski, R.J. and Hammack, L. (1998) Structure
activity relationships of phenyl alkyl alcohols,
phenyl alkyl amines and cinnamyl alcohol deriva-
tives as attractants for adult corn root worm
(coleopteran:Chrysomelidae: Diabrotica sp.).
Environ. Entomol., 27, 688–694.
Pradhanang, P.M., Momol, M.T., Olson, S.M. and
Jones, J.B. (2003) Effects of plant essential oils
on Ralstonia solanacearum population density and
bacterial wilt incidence in tomato. Plant Dis., 87,
Priestley, C.M., Williamson, E.M., Wafford, K.A. and
Sattelle, D.B. (2003) Thymol, a constituent of
thyme essential oil, is a positive allosteric
modulator of human GABA receptors and a
homo-oligomeric GABA receptor from
Drosophila melanogaster. Br. J. Pharmacol., 140,
Quarles, W. (1996) EPA exempts least-toxic pesticides.
IPM Pract., 18, 16–1779.
Raina, A.K., Bland, J., Dollittle, M., Lax, A., Boopathy,
R. and Lolkins, M. (2007) Effect of orange oil
extract on the formosan subterranean termite
(Isoptera: Rhinotermitidae). J. Econ. Entomol.,
100, 880–885.
Ray, D.P., Walia, S., Dureja, P and Singh, R.P. (2000)
Composition and repellent activity of the essential
oil of marigold (Tagetes erecta) flower. Ind. Perf.,
44, 267–270.
Rao, G.P., Pandey, A.K. and Shukla, K. (1986) Essential
oils of some higher plants vis-a-vis some legume
viruses. Indian Perf., 30, 483–486.
Reitz, S.R., Maiorino, G., Olson, S., Sprenkel, R.,
Crescenzi, A. and Momol, M.T. (2008) Interesting
plant essential oils and kaolin for the sustainable
management of thrips and tomato spotted wilt on
tomato. Plant Dis., 92, 878–886.
Rice, P.J. and Coats, J.R. (1994) Insecticidal properties
of several monoterpenoids to the housefly
(Diptera : Muscidae), red flour beetle (Coleoptera :
Tenebrionidae) and southern corn root-worm
(Coleoptera : Chrysomelidae). J. Econ. Entomol.,
87, 1172–1179.
Shaalan, E.A., Canyon, D., Younes, M.W.F., Abdel-
Wahab, H and Mansour, A. (2005) A review of
botanical phytochemicals with mosquitocidal
potential. Environ. Int., 31, 1149–1166.
Sharda, S. and Rao P.J. (2000) Effect of Ageratum
conyzoides on development and reproduction of
Spodoptera litura. Indian J. Entomol., 62, 231–
Sharma, S.S., Gill, K., Maliok, M.S. and Malik, O.P.
(2001). Insecticidal, antifeedant and growth
inhibitory activities of essential oils of some
medicinal plants. In K. Sushil, S.A. Hasan, D.
Samresh, A.K. Kukreja, S. Ashok, A.K. Sharma,
S. Srikant and T. Rakesh (eds.), Proceedings of
the National Seminar on the Frontiers of Research
and Development in Medicinal Plants, CIMAP,
Lucknow, pp. .
Shishir, T., Mittal, A.K., Kasana, V.K., Pant, A.K. and
Tandon, S. (2004) Antifeedant activity of Elsho-
ltzia essential oils against Spodoptera litura. Ann.
Plant Prot. Sci., 12, 197–198.
Singh, D., Siddiqui, M.S., Sharma, S. (1989)
Reproductive retardant and fumigant properties in
essential oils against rice weevil in stored wheat.
J. Econ. Entomol., 82, 727–733.
Singh, R., Rup, P.J. and Koul, O. (2008) Bioefficacy
of 1,8-cineole from Eucalyptus camaldulensis var.
obtusa and linalool from Luvanga scandans
against Spodoptera litura (Lepidoptera: Noctuidae)
and combination effects with some other
monoterpenoids. J. Pest Sci., (in press)
Stroh, J., Wan, M.T., Isman, M.B. and Moul, D.J.
(1998) Evaluation of the acute toxicity to juvenile
Pacific coho salmon and rainbow trout of some
plant essential oils, a formulated product, and the
carrier. Bull. Environ. Contam. Toxicol., 60, 923–
Traboulsi, A.F., Taoubi, K., El-Haj, S., Bessiere, J.M.
and Rammal, S. (2002) Insecticidal properties of
essential plant oils against the mosquito Culex pipi-
84 Biopesticides International Vol. 4, no. 1
ens molesters (Diptera : culicidae). Pest Manag.
Sci., 58, 491–495.
Tripathi, A.K., Prajapati, V. and Kumar, S. (2003)
Bioactivity of l-carvone, d-carvone and dihydro-
carvone towards three stored product beetles. J.
Econ. Entomol., 96, 1594–1601.
Tripathi, A.K., Prajapati, V., Aggarwal, K.K., Sushil
Kumar, Prajapti, V., Kumar, S. Kukreja, A.K.
Dwivedi, S. and Singh, A.K. (2000) Effects of
volatile oil constituents of Mentha species against
stored grain pests, Callosobrunchus maculatus and
Tribolium castanum. J. Med. Arom. Plant Sci.,
22, 549–556.
Tripathi, A.K., Prajanpati, V., Aggarwal, K.K. and
Kumar, S. (2001) Toxicity, feeding deterrence, and
effect of activity of 1, 8-cineole from Artemisia
annua on progeny production of Tribolium
castanaeum (Coleoptera : Tenebrionidae). J. Econ.
Entomol., 94, 979–983.
Tripathi, A.K., Prajapathi, V., Verma, N., Bhal, J.R.,
Bansal, R.P., Khanuja, S. P.S and Kumar, S. (2002)
Bioactivities of the leaf essential oils of Curcuma
longa (Var. Ch.66) on three species of stored
product beetles (Coleoptera). J. Econ. Entomol.,
95, 183–189.
Trongtokit,Y., Rongsrivam, Y., Komalamisra, N. and
Apiwathnasorn, C. (2005) Comparative repellency
of essential oils against mosquito bites. Phytother.
Res., 19, 303–309.
Tsao, R. and Zhou, T. (2000) Antifungal activity of
monoterpenoids against postharvest pathogens
Botrytis cinerea and Monilinia fructicola. J.
Essential Oil Res., 12, 113–121.
Vargas, R.I., Stark, J.D., Kido, M.H., Ketter, H.M. and
Whitehand, L.C. (2000) Methyl-eugenol and
cuelure traps for suppression of male oriental fruit
flies and melon flies (Diptera:Tephritidae) in
Hawaii: Effects of lure mixtures and weathering.
J. Econ. Entomol., 93, 81–87.
Vrushali, T., Tare, V. and Shushil, K. (2001) Bioactivity
of some medicinal plants against chosen insect
pests/vectors. In K. Sushil, S.A. Hasan, D.
Samresh, A.K. Kukreja, S. Ashok, A.K. Sharma,
S. Srikant and T. Rakesh (eds.), Proceedings of
the National Seminar on the Frontiers of Research
and Development in Medicinal Plants, CIMAP,
Lucknow, pp. .
Walia, S. (2005) Allelochemicals as Biopesticide. In
O. Koul, G.S. Dhaliwal, A. Shankar, D. Raj and
V.K. Koul (eds.), Souvenir Conference on
Biopesticides: Emerging Trends, Society of
Biopesticide Sciences, India, Jalandhar, pp. 19–
Wilson, C.L., Solar, J.M., Ghaouth, A. and Wisniewski,
M.E. (1997) Rapid evaluation of plant extracts
and essential oils for antifungal activity in Botrytis
cinerea. Plant Dis., 81, 204– 210.
Yatagi, M. (1997) Miticidal activity of tree terpenes.
Curr. Top. Phytochem., 1, 85–97.
Zambonelli, A., D”Aulerjo, A.Z., Bianchi, A. and
Albasini, A. (1996) Effects of essential oils on
phyto pathogenic fungi in vitro. J. Phytopathol.,
144, 491–494.
Zaridah, M.Z., Nor Azah, M.A., Abu Said, A. and
Mohd. Faridz, Z.P. (2003) Larvicidal properties of
citronellal and Cymbopogon nardus essential oils
from two different localities. Trop. Biomed., 20,
Accepted 01 March 2008
... In this context, essential oils (EOs) have been studied for their control of T. absoluta due to their effectiveness, and the secondary metabolites present in EOs can be used as model molecules for the synthesis of new insecticides, such as pyrethroids that were synthesized from pyrethrin produced by chrysanthemum (Tanacetum cinerariifolium) [14]. The plants studied for the development of new molecules and new active essential oils generally show medical properties and are easy to produce to obtain and extract their essential oils [15][16][17]. These plants are known to contain active ingredients that are either toxic for or beneficial to humans [15][16][17][18][19]. ...
... The plants studied for the development of new molecules and new active essential oils generally show medical properties and are easy to produce to obtain and extract their essential oils [15][16][17]. These plants are known to contain active ingredients that are either toxic for or beneficial to humans [15][16][17][18][19]. In addition, the bioactive EOs can be used to formulate new biopesticides, such as Prev-Am ® , which is mostly composed of Citrus peel oil and used to control and repel insects and mites [20]. ...
... depends on the different maturation stages [54]. Due to this natural variation, it is essential to use GC-MS to characterize the mixture of components present in studies involving botanical products such as plant extracts and EOs [15,55]. ...
Full-text available
Tuta absoluta is a pest of importance: quick to disperse and difficult to control due to the cases of resistance to insecticide active ingredients. Thus, studies using essential oils (EOs) to search for new molecules should be intensified. The objective of the present study was to evaluate the toxicity of EOs from Citrus aurantifolia (lime), Citrus aurantium (petitgrain) and Citrus aurantium bergamia (bergamot) and its major compounds against T. absoluta in a topical application test. Additionally , the demographic parameters of T. absoluta were studied after the topical application of EOs. The median lethal time (LT 50) of the population was 12h for the three EOs tested. The median lethal concentration (LC 50) was 33.75, 38.78 and 35.05 µg µL −1 for C. aurantifolia, C. aurantium and C. aurantium bergamia, respectively. As found using gas chromatography coupled to mass spectrometry (GC-MS) quantification, 44.74% of the EO of C. aurantifolia is α-terpineol, while 55.45% and 58.12% of the EO of C. aurantium and C. aurantium bergamia, respectively, is linalyl acetate. The toxicity of the major compounds was tested at concentrations equivalent to the LC 50 of the EOs, that is, 16.2 µg µL −1 for α-terpineol, and 25.8 µg µL −1 for linalyl acetate, using topical application. Both of the major compounds showed less toxicity than the EOs. In the sublethal effects tests, all the EOs negatively affected the demographic parameters of T. absoluta, with a decrease in the duration of larval instars, duration of the pupal period, fecundity, oviposition and viability of the eggs, implying a reduction in the population growth parameters of this pest. The EOs of lime, petitgrain and bergamot are toxic to T. absoluta, and low concentrations cause deleterious effects on the reproductive and population parameters of T. absoluta.
... Many essential oils, especially their monoterpene components, exhibit a variety of biological activities against a wide spectrum of insect pests. They can adversely affect growth and reproduction rate, the behavior traits of insect pests, and act as contact insecticide, fumigant, repellent, and antifeeding agents [17,18]. ...
... All fleas found were counted and removed. Infestation intensity was classified as mild (0-4 fleas per cat), medium (5-9), high (10)(11)(12)(13)(14)(15)(16)(17)(18)(19), or very high (20 or more). ...
Full-text available
There is a growing demand for natural products to be used to control fleas in pets. A prospective, double-blind, randomized, placebo-controlled study evaluated the efficacy of the biological plant-based food supplement Bioticks® (thyme, rosemary, lemon balm, fenugreek, wormwood, and lemongrass extracts) as a flea control product in naturally flea-infested cats with an indoor–outdoor lifestyle. Ten cats were used as placebo controls (group A). Ten other cats were fed the same daily diet but supplemented with Bioticks® (group B). Fleas were counted by combing at D0 and D0 + 14 days, then one, two, three, four, and five months after the start of this study. No flea treatment was administered, and no environmental changes were made for six months prior to the start and throughout this study. The product was well-tolerated. The mean flea population in group B progressively and steadily decreased to reach 3.3 ± 2.1 at month five. At the same time and under similar maintenance conditions, the average flea population in group A remained stable (14.3 ± 2.5) until the fifth month. The percentages of efficacy (Abbott formula) in group B compared to group A was 27%, 20%, 52%, 66%, and 77%, respectively, at one, two, three, four, and five months after the start of this study.
... The global use of essential oils is now steadily increasing, not only because they are a powerful source of naturally occurring botanical compounds, but also because they have favorable ecotoxicological properties. Essential oils are a mixture of secondary metabolites containing various volatile compounds responsible for many biological activities (Koul et al., 2008). In our study, eugenol was the major bioactive phenolic terpenes present in the clove oil. ...
The land snail, Theba pisana is a serious pest that adversely affects various crops in sustainable agriculture. Essential oils and their constituents represent an environmentally sound alternative to synthetic pesticides. Our study aimed to investigate the lethal and sub-lethal toxicity of clove oil and its main component eugenol to understand the mechanisms underlying its toxic action against T. pisana. The GC-MS profile of the clove oil composition was characterized. In the laboratory experiment, LD50 of clove oil and eugenol via the contact testing were determined after 48 and 72 h. Moreover, sub-lethal effects of clove oil or eugenol on the survivors following the exposure of snails to the 25 and 50% of the LD50/48 and 72 h were evaluated through using snail tissues for biochemical measurments. The GC-MS analysis showed that eugenol (64.87%) was the major constituent present in the oil. The results also showed that LD50 values at 48 and 72 h were 2006.5 and 1493.5 μg/g b.w for oil and 239.6 and 195.3 μg/g b.w for eugenol, respectively. Compared to control, the sub-lethal effects of clove oil or eugenol at 48 and 72 h showed a significant increase in reduced glutathione (GSH) levels. Catalase (CAT) and glutathione-S-transferase (GST) activities significantly elevated in oil-or eugenol-treated snails, except at low dose after 48 h. After two exposure times, snails exposed to oil or eugenol at both sub-J o u r n a l P r e-p r o o f Journal Pre-proof lethal effects had considerably higher γ-glutamyltransferase (γ-GT) and aspartate aminotransferase (AST) activities. Moreover, markedly augmentation in alkaline phosphatase (ALP) and alanine aminotransferase (ALT) activities at all exposure times, with the exception of snails treated with low dose of eugenol after 48 h was observed. Both clove oil and eugenol at the tested doses caused a significant inhibition in acetylcholinesterase (AChE) activity at two exposure times. Our findings highlight the potential of clove oil and eugenol, as an efficient natural molluscicide alternative to its synthetic counterparts for snail control.
... Beyond their insecticidal properties, essential oils extracted from Piperaceae plants have several advantages over traditional insecticides. For example, they are generally considered safe for human and animal use, biodegradable, and have lower toxicity to non-target organisms; these factors make them more environmentally friendly than many synthetic insecticides [19,20]. ...
Full-text available
The research aims to investigate the mortality effect of essential oil from Piper cordoncillo var. apazoteanum, an endemic plant from Campeche, Mexico, on early second-instar Aedes aegypti larvae; it also aims to identify the volatile compounds present in the fresh leaves of the plant. To test the effectiveness of the essential oil, we followed World Health Organization Standard Procedures. Larvae were observed for 17 consecutive days after treatment to determine the mortality and growth-inhibitory effect exerted by the essential oil. The results showed that the essential oil was effective in controlling mosquito populations. At a concentration of 800 ppm, the oil achieved an effectiveness rate of 70.00 ± 8.16% after 24 h, increasing to 100.00 ± 0.01% mortality after 72 h. With a concentration of 400 ppm, the effectiveness was 98.33 ± 0.17% by the end of the experiment. Furthermore, the obtained results demonstrated that the LC50 value was 61.84 ± 6.79 ppm, while the LC90 value was 167.20 ± 11.49 ppm. Essential oil concentrations inhibited the growth of immature insect stages, with concentrations between 800–100 ppm demonstrating very high inhibitory activity, and the lowest concentration of 50 ppm showing high inhibitory activity. The study also identified 24 chemical compounds representing 86.71% of the volatile compound composition of the fresh leaves of P. cordoncillo; the most abundant compounds were Safrole, Caryophyllene oxide, E-Nerolidol, and Calarene epoxide. The method used to extract the volatile compounds, solvent-free microwave extraction (SFME), is a promising alternative to traditional methods that avoids the use of potentially harmful solvents, making it more ecologically friendly and potentially safer for professionals handling the extracted compounds. Overall, the study demonstrates the potential of P. cordoncillo essential oil as an effective means of controlling mosquito populations, and provides valuable information on the chemical composition of the plant.Moreover, our study is the first to report on the biological activity and chemical composition of P. cordoncillo worldwide.
... Despite being efficient in most situations, synthetic insecticides can cause environmental and food contamination, in addition to contributing to biological imbalance due to the elimination of non-target organisms (Hernández & Vendramim, 1996;Valadares et al. 2020). Therefore, the use of plant extracts, associated with other practices, is an option for integrated pest management as they are obtained from renewable sources (reflecting on the low financial cost) and effectiveness in low concentrations (Ware & Whitacre 2004;Koul et al. 2008;Prates et al. 2019) and in line with global interdisciplinary sustainability requirements (Cook et al., 2004). In this work, we emphasize the ovipotential and phagodeterrent action of T. pallida extract 10% under laboratory conditions, and we encourage future fieldwork to investigate the results under natural conditions. ...
Full-text available
Diamondback moth represents one of the major Brassicaceae plagues and the main current control method relies on the agrotoxins use. The search for alternative phytosanitary control methods demonstrates that the vegetal extracts have broadly studied and now represent a relevant option to control insects-plagues in small cultivation areas. Was evaluated the effect of the aqueous extract Tradescantia pallida 10% in oviposition and the feeding preference of Plutella xylostella, in laboratory conditions. That plant does not present herbivory reports, which raises the hypothesis of representing an efficient control alternative. P. xylostella couples introduced in experimentation cages for 10 days, to assess the activity of oviposition, being exposed to the botanic extract in the feeding and the oviposition substrate, with the eggs average number per day and fertility being assessed. To assess feeding, two tests developed: free choice and no choice of food source during 48 hours of evaluation. The results indicate that the aqueous T. pallida extract changes the oviposition activity of P. xylostella, reducing the average number of eggs per day and the fertility. It was also possible to observe the non-preference, regarding feeding, for substrates that were treated with the extract. The results observed in the study can contribute to amplify the small producers decision-making processes and the involved sectors regarding the choice of supplies that respect environmental and human health.
... Some essential oils contain compounds benzene and the OH group, so that it can act as a botanical pesticide. Essential oil-based pesticide registration has escaped from the EPA (Environmental Protection Agency) and declared safe from the GRAS (Generally Recognized as Safe) so friendly to humans and the environment [8]. Same researcher report that the effect of essential oil to antifungal activity and bio pesticide [9][10][11][12]. ...
... It is also apparent that resistance to botanical pesticides will develop more slowly than synthetic pesticides due to the complex mixtures of active elements. This could reduce the risks of high frequencies of resistant alleles established in natural pest populations (Koul et al. 2008, Rattan 2010, Van Leeuwen et al. 2010). ...
The negative side effects of synthetic pesticides have drawn attention to the need for environmentally friendly agents to control arthropod pests. To identify promising candidates as botanical pesticides, we investigated the acaricidal and insecticidal activities of 44 plant-derived essential oils (EOs) against Tetranychus urticae Koch and Myzus persicae Sulzer. Among the tested EOs, Tasmannia lanceolata (Poir.) A.C.Sm. (Tasmanian pepper) essential oil (TPEO) exhibited strong acaricidal and insecticidal activity. Mortality rates of 100% and 71.4% against T. urticae and M. persicae, respectively, were observed with TPEO at a concentration of 2 mg/ml. Polygodial was determined to be the primary active component after bioassay-guided isolation of TPEO using silica gel open-column chromatography, gas chromatography, and gas chromatography–mass spectrometry. Polygodial demonstrated acaricidal activity against T. urticae with mortality rates of 100%, 100%, 61.9%, and 61.6% at concentrations of 1, 0.5, 0.25, and 0.125 mg/ml, respectively. Insecticidal activity against M. persicae was also evident, with mortality rates of 88.5%, 85.0%, 46.7%, and 43.3% at respective concentrations of 1, 0.5, 0.25, and 0.125 mg/ml. Insecticidal and acaricidal activities of TPEO were greater than those of Eungjinssag, a commercially available organic agricultural material for controlling mites and aphids in the Republic of Korea. These findings suggest that TPEO is a promising candidate for mites and aphids control.
There is an urgent need for the development of sustainable and eco-friendly pesticide formulations since common synthetic pesticides result in many adverse effects on human health and the environment. Essential oils (EOs) are a mixture of volatile oils produced as a secondary metabolite in medicinal plants, and show activities against pests, insects, and pathogenic fungi. Their chemical composition is affected by several factors such as plant species or cultivar, geographical origin, environmental conditions, agricultural practices, and extraction method. The growing number of studies related to the herbicidal, insecticidal, acaricidal, nematicidal, and antimicrobial effects of EOs demonstrate their effectiveness and suitability as sustainable and environment-friendly biopesticides. EOs can biodegrade into nontoxic compounds; at the same time, their harmful and detrimental effects on non-target organisms are low. However, few biopesticide formulations based on EOs have been turned into commercial practice upto day. Several challenges including the reduced stability and efficiency of EOs under environmental conditions need to be addressed before EOs are widely applied as commercial biopesticides. This work is an overview of the current research on the application of EOs as biopesticides. Findings of recent studies focusing on the challenges related to the use of EOs as biopesticides are also discussed.
Essential oils of Eulcalyptus globulus, Lavender officinalis, Rosemarinus officinalis, and Thymus vulgaris were examined for their repellent activities against Culex pipiens pallens. All 4 essential oils effectively repelled adult mosquitoes on hairless mice. Essential oil of T. vulgaris (thyme) had potent repellent activity within the tested materials, with a protection rate of 91% at a concentration of 0.05% topical treatment. Thyme essential oil significantly extended the duration of protection until 3 bites by mosquitoes. With gas chromatography-mass spectrometry analysis, thyme essential oil was a rich source of 5 monoterpenes, including in descending order thymol, p-cymene, carvacrol, linalool, and a-terpinene. These 5 monoterpenes also were assessed to determine their repellent activities to the mosquitoes. alpha-Terpinene had a potent repellent activity with a protection rate of 97% at a concentration of 0.05% topical treatment. Additionally, carvacrol and thymol showed an equivalent level of repellency. A spray-type solution containing 2% alpha-terpinene was tested for its repellent activity against Cx. pipiens. This solution showed stronger repellent activity than the currently used repellent N,N-diethyl-m-methylbenzamide (deet).