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Insecticidal and Biting Deterrent Activity of Rose-scented Geranium (Pelargonium spp.) Essential Oils and Individual Compounds Against Stephanitis pyrioides and Aedes aegypti.


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Background Rose-scented geranium, Pelargonium spp., essential oils from the cultivars Bourbon', China', Egypt', Rober's Lemon Rose' and Frensham' were analyzed by GC-FID and GC-MS. A total of 136 compounds were identified from five essential oils, constituting 85.5-99.7% of the oils. Essential oils and pure compounds were evaluated for their insecticidal activity against Stephanitis pyrioides and larvicidal and biting deterrent activity against Aedes aegypti. ResultsAll five geranium oils were toxic to S. pyrioides, and four of these five were more potent than malathion and neem. Trans-nerolidol (LD50 = 13.4ppm) was the most toxic compound against one-day-old Ae. aegypti larvae, followed by geraniol (49.3ppm), citronellol (49.9ppm) and geranyl formate (58.5ppm). Essential oil of cultivar Egypt' at 100g cm(-2) [biting deterrent index (BDI)=0.8] showed the highest biting deterrent activity, followed by cultivars Frensham' (BDI = 0.76), China' (BDI = 0.72), Rober's Lemon Rose' (BDI = 0.63) and Bourbon' (BDI = 0.45) essential oils. Among the pure compounds, the biting deterrent activity of geranic acid (BDI = 0.99) was not significantly different from that of N,N-diethyl-m-toluamide (DEET). Conclusion Essential oils and pure compounds showed insecticidal activity against S. pyrioides and Ae. aegypti. The high biting deterrent activity of geranic acid points to the need for further research. (c) 2013 Society of Chemical Industry
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Research Article
Received: 26 October 2012 Revised: 11 January 2013 Accepted article published: 19 February 2013 Published online in Wiley Online Library: 15 April 2013
( DOI 10.1002/ps.3518
Insecticidal and biting deterrent activity
of rose-scented geranium (Pelargonium spp.)
essential oils and individual compounds
against Stephanitis pyrioides and Aedes aegypti
Abbas Ali,aChristine C Murphy,bBetul Demirci,cDavid E Wedge,dBlair J
Sampson,eIkhlas A Khan,a,f,g K Husnu Can Baserc,h and Nurhayat Tabancaa
BACKGROUND: Rose-scented geranium, Pelargonium spp., essential oils from the cultivars ‘Bourbon’, ‘China’, ‘Egypt’, ‘Rober’s
Lemon Rose’ and ‘Frensham’ were analyzed by GC-FID and GC-MS. A total of 136 compounds were identified from five essential
oils, constituting 85.5 –99.7% of the oils. Essential oils and pure compounds were evaluated for their insecticidal activity against
Stephanitis pyrioides and larvicidal and biting deterrent activity against Aedes aegypti.
RESULTS: All five geranium oils were toxic to S. pyrioides, and four of these five were more potent than malathion and neem.
Trans-nerolidol (LD50 =13.4 ppm) was the most toxic compound against one-day-old Ae. aegypti larvae, followed by geraniol
(49.3 ppm), citronellol (49.9 ppm) and geranyl formate (58.5 ppm). Essential oil of cultivar ‘Egypt’ at 100 µgcm
deterrent index (BDI) =0.8] showed the highest biting deterrent activity, followed by cultivars ‘Frensham’ (BDI =0.76), ‘China’
(BDI =0.72), ‘Rober’s Lemon Rose’ (BDI =0.63) and ‘Bourbon’ (BDI =0.45) essential oils. Among the pure compounds, the biting
deterrent activity of geranic acid (BDI =0.99) was not significantly different from that of N,N-diethyl-m-toluamide (DEET).
CONCLUSION: Essential oils and pure compounds showed insecticidal activity against S. pyrioides and Ae. aegypti. The high
biting deterrent activity of geranic acid points to the need for further research.
2013 Society of Chemical Industry
Keywords: rose-scented geranium; citronellol; geranic acid; geraniol; nerolidol; Stephanitis pyrioides;Aedes aegypti
Mosquitoes transmit pathogens that cause serious human
diseases, including malaria, Japanese encephalitis, yellow fever,
dengue and filariasis. Insecticides from various chemical groups
are the basic tools used for management of mosquito populations.
Owing to the continuous use of insecticides, mosquitoes have
developed resistance against these chemicals, and vector
population management has become difficult.1Lace bugs, such as
the azalea lace bug, Stephanitis pyrioides (Scott), are serious pests
of plants of horticultural importance, including ornamentals and
flowering plants in small gardens. Commercially available pesti-
cides such as malathion are registered for use in these gardens.
The toxicity of many synthetic chemicals and the development of
resistance in insects pose a great challenge for the management
of these pests. Therefore, there is a need for the development of
alternative insecticides to control small garden insect pests such
as lace bugs and for insect repellents to manage disease vectors
such as Aedes aegypti (L.), which transmits viral pathogens of
diseases including yellow fever and dengue. Plants are a potential
source of new natural insecticides and insect repellents. Not only
are these natural compounds a source of new insecticides and
insect repellents, botanical chemical derivatives may also be more
environmentally friendly than synthetic chemicals.2
Rose-scented geranium, Pelargonium species, a member of
the Geraniaceae family, produces many fragrant essential oils.
Correspondence to: Abbas Ali, National Center for Natural Products Research,
University of Mississippi, University, MS 38677, USA. E-mail:
aNational Center for Natural Products Research, University of Mississippi,
University, MS, USA
bEntomology, Soils and Plant Sciences, Clemson University, Clemson, SC, USA
cFaculty of Pharmacy, Department of Pharmacognosy, Anadolu University,
Eskisehir, Turkey
dUSDA-ARS-NPURU, University of Mississippi, University, MS, USA
eUSDA-ARS, Thad Cochran Southern Horticultural Laboratory, Poplarville, MS,
fDepartment of Pharmacognosy, School of Pharmacy, University of Mississippi,
University, MS, USA
gDepartment of Pharmacognosy, College of Pharmacy, King Saud University,
Riyadh, Saudi Arabia
hDepartment of Botany and Microbiology, College of Science, King Saud
University, Riyadh, Saudi Arabia
Pest Manag Sci 2013; 69: 1385 –1392 c
2013 Society of Chemical Industry
1386 Abbas Ali et al.
Rose-scented geranium essential oil is commercially available in
the Reunion Islands (Bourbon), China, Egypt, India and France.
Plants from each of these regions have their own unique oil
composition, with the ratio of citronellol to geraniol being a key
indicator of essential oil quality.3Although the complex chemistry
of geranium oil is well documented, use of these oils and their
terpenoid components (citral, geraniol, citronellol and linalool)
in the control of disease vectors has not been well studied.46
Likewise, the essential oils of cultivars ‘Frensham’ and ‘Rober’s
Lemon Rose’ are known to have a great value as fragrant oils
and to be a valuable source of terpenoids, but their chemical
composition and biological activity are not well studied.6In the
present study, the composition of essential oils of rose-scented
geranium oils collected from different parts of the world was
determined. These essential oils and individual compounds were
also evaluated for their insecticidal activity against adult S.pyrioides
and their larvicidal and biting deterrent activity against Ae. aegypti.
Citronellol,geraniol,citral, citronellyl formate,(E)-nerolidol, geranic
acid and linalool (>96%) were supplied by Sigma-Aldrich (St
Louis, MO), and rose-scented geranium essential oils of cultivars
‘Bourbon’, ‘China’ and ‘Egypt’ were purchased from Alexander
Essentials Ltd (Morecambe, Lancs, UK).
2.1 Plant material and distillation
The essential oils of cultivars ‘Frensham’ and ‘Rober’s Lemon
Rose’ were obtained from plants grown at the Clemson University
Heirloom Garden in Clemson, South Carolina. These plants were
grown on a well-drained, red clay kaolinite soil with high iron and
very high organic matter (Ultisols soil, subcategory Humults). A 6
inch layer of composted chicken manure was incorporated into the
soil about1 week before planting.Cultivars ‘Frensham’ and‘Rober’s
Lemon Rose’, purchased from Richters nursery (Goodwood, ON,
Canada) were propagated from the stem cuttings, and 15-30-
15 fertilizer (Scotts Miracle-Gro Company, Marysville, OH) was
added to the soil. Neither of the two cultivars survived the winter
in Clemson. Cuttings from the established nursery plants were
planted in late spring after the threat of frost had passed, and their
bases were mulched with additional composted chicken manure.
Nine plants from each cultivar were grown in 2 ×6 m plots. Plants
were hand watered as needed, and no pesticides were applied.
At monthly intervals, the top third of the plants was harvested
at around 13:00 h. Harvested plant parts were dried for 24–48 h
at 24 C and distilled for 3 h using a Clevenger-type apparatus.
Essential oils yielded during hydrodistillation were analyzed by GC
and GC/MS to determine the chemical compound profile.
2.2 GC and GC-MS analysis of the essential oils
The GC-MS analysis was carried out on an Agilent 5975 GC-MSD
system (SEM Ltd, Istanbul, Turkey). An Innowax FSC column (60 m
×0.25 mm, 0.25 µm film thickness) was used, with helium as the
carrier gas (0.8 mL min1). GC oven temperature was kept at 60 C
for 10 min and programmed to 220 C at a rate of 4 Cmin
constant at 220C for 10 min and then programmed to 240 Cata
rate of 1 Cmin
1. The split ratio was adjusted at 40:1. The injector
temperature was set at 250 C. Mass spectra were recorded at
70 eV, with a mass range from m/z35 to 450.
The GC analysis was carried out on an Agilent 6890 N GC system.
The FID detector temperature was set at 300 C. To obtain the
same elution order as with GC-MS, simultaneous autoinjection was
achieved with a duplicate column under the same temperature
program. Relative percentage amounts of the isolated compounds
were calculated from FID chromatograms.
2.3 Identification of components
Essential oil components were identified by comparing their
relative retention times with those of authentic samples or by
comparing their relative retention indices (RRIs) with those of
a series of n-alkanes. Computer matching against commercial
(Wiley GC-MS Library, Adams Library, MassFinder 3 Library) and in-
house (Bas¸ er Library) essential oil constituents built up by genuine
compounds and components of known oils, as well as MS literature
data,710 was used for identification.
2.4 Dose–mortality bioassays against adult azalea lace bug
Adult S. pyrioides were collected by using electric aspirators
(Hausherr’s Machine Works, Tom’s River, NJ) from bouquets of
azalea terminals (Rhododendron sp.). These plants were constantly
maintained in plant growth chambers (Percival Scientific, Perry,
IA) at a temperature of 27 C and 65% RH with a 14:10 h
L:D photoperiod. Essential oils of five cultivars of rose-scented
geranium (nine replications) were tested against S. pyrioides at
doses ranging from 0 to 10 000 ppm. Selection of 10 000 ppm as
the highest dose was based on the standard evaluation method
used for essential-oil-based insecticides such as Ecotrol.11,12 All oil
dilutions were freshly prepared using dimethylsulfoxide (DMSO) as
solvent, and a 10% aqueous solution of DMSO was used as a solvent
control, which represented the 0 ppm dose in all bioassays. The
rose-scented geranium essential oils tested included five cultivars:
‘Bourbon’, ‘China’, ‘Egypt’, ‘Rober’s Lemon Rose’ and ‘Frensham’.
Eight lead compounds identified from these oils geranic acid,
geraniol, citral, citronellol, citronellyl formate, nerol, trans-nerolidol
and linalool were also evaluated for their bioactivity against
S. pyrioides. A quantity of 20 µL of each treatment and control
solution was added to individual plastic wells of a standard 96-well
microtiter plate in a randomized complete block design (RCBD). To
prevent bugs from drowning in residual fluid, an absorbent disc of
Whatman No. 2 filter paper was placed at the bottom of each well.
Three adult azalea lace bugs were transferred from their holding
vials to treatment and control wells. Mortality data were recorded
by observing these bugs under a dissecting microscope at 1 h
intervals for 5 h at 21 C. Between these observations, bugs were
kept at 23 C in a separate growth chamber. Bioassays were carried
out to develop dose–response curves. Technical-grade malathion
and neem oil were included as positive controls.
2.5 Larval bioassays against Aedes aegypti
Aedes aegypti used in larvicidal and biting deterrence bioassays
originated from a laboratory colony maintained at the Mosquito
and Fly Research Unit at the Center for Medical, Agricultural and
Veterinary Entomology, United States Department of Agriculture,
Agriculture Research Service, Gainesville, Florida, since 1952 using
standard procedures.13 Eggs were received and stored in the
authors’ laboratory (Biological Field Station, The University of
Mississippi, Abbeville, MS) until needed. Bioassays were conducted
using a system described by Pridgeon et al.13 to determine the
larvicidal activity of individual compounds from various cultivar
essential oils against Ae. aegypti. Eggs were hatched and larvae
were held in a room maintained at a temperature of 27 ±2C
and 60 ±10% RH. Five one-day-old larvae were transferred to c
2013 Society of Chemical Industry Pest Manag Sci 2013; 69: 1385 –1392
Insecticidal and biting deterrent activity of rose-scented geranium
individual wells of a 24-well tissue culture plate in a 30–40 µL
droplet of water. A quantity of 50 µL of larval diet of 2% slurry
of 3:2 beef liver powder (Now Foods, Bloomingdale, Illinois) and
brewer’s yeast (Lewis Laboratories Ltd, Westport, CT) and 1 mL
of deionized water were added to each well using a Finnpipette
stepper (Thermo Fisher, Vantaa, Finland). All the compounds to
be tested were diluted in DMSO. After treatment application, the
plates were swirled in clockwise and counterclockwise motions
and front and back and side to side 5 times to ensure even mixing
of the chemicals. Larval mortality was recorded at 24 and 48 h
post-treatment. Larvae were deemed dead if they showed no
movement in the well after being prodded with a pipette tip. A
series of five dosages were used in each treatment to obtain a
range of mortality between 0 to 100%. Treatments were replicated
10 times for each compound.
2.6 Mosquito biting bioassays
Mosquitoes were reared to the adult stage by feeding larvae a
diet of 2% slurry of 3:2 beef liver powder and brewer’s yeast. Eggs
on a piece of paper were hatched in a cup filled with 100 mL
of deionized water containing a small quantity of larval diet and
maintained under vacuum (1 h). Larvae were removed from
the vacuum and held overnight in the cup. These larvae were
then transferred into 500 mL cups (about 100 larvae per cup)
filled with water. Larval diet was added every day until pupation,
and the mosquitoes were kept in an environmentally controlled
room at a temperature of 27 ±2Cand60±10% RH with a
12:12 h L:D photoperiod. Adult mosquitoes were fed from cotton
pads moistened with 10% sucrose solution placed on the top
of screens of 4 L cages. Mated females (10–18 days old) used in
these bioassays were deprived of sucrose for 24 h prior to the test,
but had free access to water-soaked cotton. A six-cell Klun and
Debboun (K & D) module bioassay system was used to quantify the
biting deterrence of essential oils and pure compounds.14 Here,
the term ‘feeding deterrent’ is used in the sense of Dethier et al.,15
i.e. a chemical that inhibits feeding when present in a place where
the insects feed in its absence. This is in contrast to a repellent,
a chemical that causes insects to move away from a chemical or
its source. The K & D system consists of a six-well reservoir, with
each of the 4 ×3 cm wells containing 6 mL of feeding solution. As
reported by Ali et al.,16 a citrate–phosphate–dextrose–adenine
(CPDA-1) +ATP solution was used instead of human blood. CPDA-
1 and ATP preparations were freshly made on the day of the
test, and the mixture contained a red dye for verifying whether
mosquitoes had imbibed the solution. N,N-Diethyl-m-toluamide
(DEET) (97% purity) was obtained from Sigma-Aldrich and used as
a positive control. Molecular-biology-grade ethanol was obtained
from Fisher Scientific Chemical Co. (Fairlawn, NJ). Stocks and
dilutions of all essential oils, individual compounds and DEET were
prepared in ethanol. All essential oils were evaluated at dosages
of 10 and 100 µgcm
2, and DEET at a concentration of 4.8 µg
cm2was used as positive control. Stock solutions were kept in a
refrigerator set at 3 –4 C.
Duringthebioassay, the temperatureofthe solutioninreservoirs
covered with a collagen membrane was maintained at 37.5 C
by circulating water through the reservoir with a temperature-
controlled circulatory bath. The test compounds and controls
were randomly applied to six 4 ×3 cm marked portions of nylon
organdy strip, which was positioned over the six membrane-
covered wells. A Teflon separator was placed between the treated
cloth and the module. The K & D module containing five females
of Ae. aegypti per cell was positioned over the six wells. Trap
doors were opened and mosquitoes allowed access for a 3 min
period, after which they were collected back into the module.
Mosquitoes were squashed, and the presence of red dye in the
gut was used as an indicator of feeding. A replicate consisted of
six treatments: four oils, DEET (positive control) and 100% ethanol
(solvent control). Five replicates were conducted per day, using
new batches of mosquitoes for each. Bioassays were conducted
between 13:00 and 16:00 h, and ten replications were conducted
for each treatment.
2.7 Data analyses
Mortality data of adult azalea lace bug and mosquito larvae were
corrected for the control mortality using Abbott’s formula.17 Loge
transformations of mortality data and ANCOVA analyses in a RCBD
design were used to analyze S. pyrioides data as described in
previous studies.11,12 LD50 values for mosquito larvicidal data were
calculated using SAS Proc Probit.18
The proportion not biting (PNB) was calculated using the
following formula:
PNB =1total number of females biting
total number of females
As the K & D module bioassay system can handle only four
treatments at a time along with negative and positive controls,
in order to make direct comparisons among more than four test
compounds, and to compensate for variation in overall response
among replicates, the biting deterrent effect was quantified as the
biting deterrence index (BDI). The BDIs were calculated using the
following formula:
where PNBi,j,kdenotes the proportion of females not biting test
compound ifor replication jand day k(i=1–4, j=1–5, k=1–2),
PNBc,j,kdenotes the proportion of females not biting the solvent
control for replication jand day k(j=1–5, k=1–2) and PNBd,j,k
denotes the proportion of females not biting in response to DEET
(positive control) for replication jand day k(j=1–5,k=1–2). This
formula makes an adjustment for interday variation in response
and incorporates information from the solvent control as well as
the positive control.
A BDI value of 0 indicates an effect similar to ethanol, while
a value significantly greater than 0 indicates a biting deterrent
effect relative to ethanol. BDI values not significantly different
from 1 are statistically similar to DEET. BDI values were analyzed
using SAS Proc ANOVA, and means were separated using the
Ryan–Einot–Gabriel –Welsch multiple range test.18
3.1 Chemical yield and composition of the essential oils
Cultivar ‘Rober’s Lemon Rose’ produced a pale-green oil with a
minty green rose scent and had a mean fresh/dry weight (FW/DW)
of 0.2%/1.48%. Cultivar ‘Frensham’ produced a lemon-yellow
essentialoilwith an averageFW/DW of 0.15%/0.58%.Characterized
compounds of these oils with their relative percentages are
listed in Table 1. A total of 136 compounds were identified
from essential oils of cultivars ‘Bourbon’, ‘China’, ‘Egypt’, ‘Rober’s
Lemon Rose’ and ‘Frensham’. The combined percentages of these
compounds in essential oils ranged from 85.5 to 99.7% (Table 1).
Pest Manag Sci 2013; 69: 1385 –1392 c
2013 Society of Chemical Industry
1388 Abbas Ali et al.
Table 1. The composition of the essential oils of rose-scented
geranium from samples collected from various parts of the
1032 α-Pinene 0.8 0.8 0.4 0.1
1048 2-Methyl-3-buten-2-ol ————0.2
1118 β-Pinene 0.2 0.2 — —
1174 Myrcene 0.1 — —
1203 Limonene 0.6 0.6 0.2 0.1
1218 β-Phellandrene 0.1 — —
1246 (Z)-β-ocimene 0.3 0.2 — —
1266 (E)-β-ocimene 0.1 — —
1280 p-Cymene 0.1 0.1 0.1 trc0.7
1290 Terpinolene 0.1 — —
1348 6-Methyl-5-hepten-2-one 0.1 — 0.9
1362 cis-Rose oxide 0.9 0.9 1.3 0.7 0.5
1377 trans-Rose oxide 0.4 0.4 0.5 0.3 0.2
1391 (Z)-3-Hexenol — — — tr
1432 Photocitral B ————0.3
1450 trans-Linalool oxide (Furanoid) 0.1 0.2 0.4 0.3
1466 α-Cubebene tr tr 0.2 — —
1467 6-Methyl-5-hepten-2-ol ————tr
1475 Menthone 1.1 1.0 0.7 1.0
1478 cis-Linalool oxide (Furanoid) tr 0.1 0.1 — 0.3
1487 Citronellal tr 0.1 0.1 0.4
1493 α-Ylangene 0.1 — —
1494 (Z)-3-Hexenylisovalerate ————0.1
1495 cis/cis-Photocitral ————0.2
1497 α-Copaene tr 0.5 —
1503 Isomenthone 7.7 7.9 7.3 5.5
1519 trans/trans-Photocitral ————0.3
1528 α-Bourbonene 0.1 — —
1535 β-Bourbonene 0.2 0.2 1.1 0.5 0.5
1553 Linalool 10.4 10.9 7.5 0.1 1.1
1571 Methyl citronellate — — — tr
1577 Neoisopulegol tr 0.3 tr
1583 Isopulegol 0.1 0.1 0.1 0.7 0.3
1589 β-Ylangene 0.1 0.1 —
1594 α-trans-β-Bergamotene ————tr
1597 β-Copaene 0.1 0.1 — tr
1600 β-Elemene 0.4 0.4 0.2
1602 6-Methyl-3,5-heptadien-2-one ————tr
1611 Terpinen-4-ol 0.3 0.3 — —
1612 β-Caryophyllene 0.4 0.3 1.1
1613 β-Cedrene ————0.2
1617 6,9-Guaiadiene 0.3 0.5 0.4
1628 Citronellyl formate 10.5 10.5 7.0 13.3 1.0
1628 Aromadendrene ————0.2
1632 Neoisomenthol — — — 0.2
1638 Menthol tr — —
1639 trans-p-Mentha-2,8-dien-1-ol————0.2
1655 2,6-Dimethyl-5-hepten-1-ol 0.2 —
1661 Alloaromadendrene 0.2 0.1 —
1668 Dimethyl octanol 0.2 0.2
1668 Citronellyl acetate 0.3 0.3 0.2 0.4
1677 epi-Zonarene 0.1 — —
1681 (Z)-3-Hexenyl tiglate 0.2 0.2
1684 Neryl formate 0.3 0.2
Table 1. continued
1687 α-Humulene 0.1 0.1 0.3 — —
1694 Neral 0.5 0.5 0.4 0.1 7.2
1704 γ-Muurolene — — — 0.1
1706 α-Terpineol 1.3 1.2 0.6 — 0.4
1708 Ledene 0.2 — —
1715 Geranyl formate 4.9 4.8 3.0 tr
1726 Germacrene D 0.1 0.1 1.1
1729 Citronellyl propionate 0.9 0.9 0.5 0.7
1740 α-Muurolene tr tr tr 0.2 —
1742 Geranial 1.2 1.4 0.8 0.2 17.9
1755 Bicyclogermacrene — 0.2 —
1758 cis-Piperitol ————0.4
1758 (E,E)-α-Farnesene 0.1 0.5 0.1 — —
1765 Geranyl acetate 0.4 0.1 0.4
1772 Citronellol 31.1 29.7 30.1 50.9 8.5
1773 δ-Cadinene 0.4 tr 0.6 0.2 —
1776 γ-Cadinene — 0.2 — —
1786 ar-Curcumene ————0.2
1804 Citronellyl butyrate ————tr
1808 Nerol 0.9 0.9 0.4 — 1.3
1809 Citronellyl butyrate 0.2 0.2 0.4 0.4 —
1819 Geranyl isobutyrate 0.3 0.3 0.1
1825 Geranyl propionate 1.0 1.0 0.7
1834 Citronellyl isovalerate — — — tr —
1857 Geraniol 16.0 14.7 15.2 0.1 1.6
1864 p-Cymen-8-ol ————0.5
1868 (E)-Geranylacetone ————tr
1872 cis-Myrtanol — — — 0.1
1879 trans-Myrtanol — — — 0.5
1896 Phenyl ethyl isobutyrate 0.1 tr
1900 Citronellyl valerate (= C. pentanoate)— 0.2 —
1901 Geranyl butyrate 1.2 1.3 1.1 tr
1916 α-Agarofuran 0.1 0.1 0.3
1933 Neryl valerate tr tr
1937 Phenyl ethyl alcohol — — — tr —
1941 α-Calacorene 0.1 — —
1953 Geranyl valerate — — — tr —
1953 Citronellyl 4-methylvalerate 0.1 0.5
1957 Hydroxy citronellol ————1.8
1984 Furapelargone A — — — 0.1
1988 Nerolidol oxide-I ————1.6
2000 Citronellyl hexanoate — — — tr 0.9
2008 Caryophyllene oxide 0.2 0.3 0.2 0.9
2016 Nerolidol oxide-II tr 1.8
2020 (E)-Citronellyl tiglate 0.4 0.4 0.2 1.1 0.2
2030 Methyl eugenol ————tr
2046 Norbourbonone — — 0.1
2050 (E)-Nerolidol — — — 0.3 23.8
2071 Humulene epoxide-II 0.2 0.1 0.2
2080 Junenol (= eudesm-4(15)-en-6-ol) — — — 0.3
2080 Cubenol — 0.3 — —
2088 1-epi-Cubenol 0.1 0.1 0.2 — —
2096 Citronellyl heptanoate 0.2 0.2 tr
2098 Globulol 0.1 — —
2105 Geranyl caproate (= G. hexanoate) 0.2 — 1.9
2105 Furopelargone B 0.1 1.1 tr c
2013 Society of Chemical Industry Pest Manag Sci 2013; 69: 1385 –1392
Insecticidal and biting deterrent activity of rose-scented geranium
Table 1. continued
2122 Neryl tiglate 2.2 2.6 2.0 0.3
2127 10-epi-γ-eudesmol 4.8 — —
2131 Hexahydrofarnesyl acetone — — — — 0.1
2143 Cedrol — — — — 0.5
2144 Spathulenol 0.1 0.2 0.4 0.3 —
2157 Geranyl tiglate 0.4
2157 5-epi-7-epi-α-Eudesmol 0.1 — —
2185 γ-Eudesmol 0.2 — —
2187 T-Cadinol 0.7 —
2209 Citronellyl caprylate (= C. octanoate )— — — — 0.4
2200 Agarospirol 0.1 — —
2200 (E)-3,7-Dimethyl-5-octen-1,7-diol 1.4 —
2209 T-Muurolol 0.1 0.6 —
2214 Phenyl ethyl tiglate 0.1 0.2 0.9 2.5
2237 Valerianol 0.1 0.1 0.3 — —
2247 trans-α-Bergamotol — 0.1 — —
2255 α-Cadinol 0.1 0.1 1.7 —
2257 β-Eudesmol — 0.5
2260 Citronellic acid 0.7
2260 4α-Hydroxy-dihydroagarofuran tr 0.1 0.3 — —
2271 (2E,6E)-Farnesyl acetate tr tr
2273 Selin-11-en-4αlin 0.1 —
2308 Nerolic acid — — — — 1.0
2349 3,7-Dimethyl-7-octen-1,6-diol 0.5 —
2349 Geranic acid 0.1 5.6
2655 Benzyl benzoate 0.1 0.2
Total 99.7 98.5 98.5 92.6 85.5
aRRI =relative retention index calculated against n-alkane percentage
calculated from FID data.
bA=cultivar ‘Bourbon’; B =cultivar ‘China’; C =cultivar ‘Egypt’; D =cultivar
‘Rober’s Lemon Rose’; E =cultivar ‘Frensham’.
ctr =Traces (<0.1%).
Sixty compounds comprising 92.6% of the total essential oils
were identified from cultivar ‘Rober’s Lemon Rose’. The ‘Rober’s
Lemon Rose’ essential oil contained 0.5% 6,9-guaiadiene, 5.5%
isomenthone and 13.3% citronellyl formate, which are mostly
present in commercial geranium essential oil, but the citronellol
(50.9%) and geraniol (0.1%) contents differed from other geranium
essential oils. Citronellol (C) was found to be the major component
of commercial geranium oils and was double the quantity of
geraniol (G) (C:G ratio 2:1). Typically, the essential oil of ‘China’
would be expected to have a C:G ratio of 3:1 or 4:1, and ‘Bourbon’
or ‘Egypt’ essential oils a ratio closer to 1:1.3,19 In the present study,
linalool, citronellyl formate, isomenthone and geranyl formate
were present in lesser amounts. Only the commercial oil of
‘Egypt’ had 0.3% 6.9-guaiadiene and 4.8% 10-epi-γ-eudesmol. The
compound 10-epi-γ-eudesmol is present in essential oil of cultivar
‘Egypt’ and not found in essential oils of ‘China’ or ‘Bourbon’
Fifty-three components of cultivar ‘Frensham’ comprised 85.5%
of the total essential oil. The major compounds were (E)-nerolidol
(23.8%), geranial (17.9%), citronellol (8.5%), neral (7.2%) and
geranic acid (5.6%). Levels of citral, an α,β-unsaturated aldehyde,
were lower than in lemongrass, and the neral to geranial ratio was
favorable, as geranial has been shown to be the biologically active
isomer.21 As nerolidol, (a sesquiterpene approved by the FDA as
a food flavoring agent), exhibits antineoplastic, antimalarial and
antileishmanial activity,22 and geranic acid (5.6%) has been shown
to be a tyrosinase inhibitor,23 this essential oil may also have
similar medicinal properties. The linalool contents in essential oils
of cultivars ‘Rober’s Lemon Rose’ (0.1%) and ‘Frensham’ (1.1%)
were significantly lower than in cultivars ‘Bourbon’ (10.4%), ‘China’
(10.9%) and ‘Egypt’ (7.5%). Cultivar ‘Rober’s Lemon Rose’ was
also rich in non-phenolic monoterpenes, i.e. citronellol (50.9%),
citronellyl formate (13.3%) and isomenthone (5.5%), whereas it
contained only 0.1% geraniol. The essential oil from cultivar
‘Rober’s Lemon Rose’, as described by Lis-Balchin,5included
linalool, cis-rose oxide, trans-rose oxide, isomenthone and geraniol.
Essential oil of ‘Rober’s Lemon Rose’ was lower in the above-
mentioned compounds but higher in citronellol and citronellyl
formate. The citronellol to geraniol ratio of 100:1, which is similar
to that of the cultivar ‘Bourbon’ essential oil, produces less fragrant
oils that are less likely to be used in the perfume trade. However,
such a ratio of chemicals may have potent antibacterial, antifungal
and insecticidal properties.
The composition of essential oils varies as a function of many
factors, including plant and leaf age, crop stage, harvesting
conditions and environment factors.24 Individual constituents can
also vary as a function of the temperature, photoperiod and
amount of rainfall. Geraniol and linalool are known to decrease
in concentration when temperatures are greater than 40 Cand
increase as temperatures decrease, while citronellol percentage
increases in essential oil extracted from plants grown in climatic
zones of higher temperatures.25 Plants subjected to drought stress
had essential oils that were higher in citronellol.26 As the chemical
profile of the essential oil is altered by environmental effects, the
essential oils from the same plant may show variable biological
activity depending on the sources of the samples.
3.2 Toxicity against azalea lace bugs
Toxicity data of rose-scented geranium essential oils and pure
compounds against S. pyrioides are given in Table 2. Geranium
essential oils killed S. pyrioides faster than malathion (t=3.26,
P<0.0014) (Fig. 1) at a dose of 10 000 ppm. Essential oils of
cultivars ‘Bourbon’ and ‘China’ showed highest mortality and killed
96 –100% of bugs within 2 h of exposure. Essential oils of ‘Bourbon’,
‘China’, ‘Egypt’ and ‘Robers Lemon Rose’ were more toxic than
malathion (t>2.60, P<0.01). Essential oil of ‘Frensham’ showed
significantly lower toxicity against S. pyrioides than malathion (t
=−0.49, P>0.60). All the rose-scented geranium essential oils
were more toxic than the commercial formulation of neem oil and
malathion, except for cultivar ‘Frensham’, which showed lower
activity than neem oil and malathion. Based on the bioassay
results, the insecticidal activity of these oils against S. pyrioides is
mostly attributable to the monoterpenoid components, including
geraniol, citral, citronellol and nerol (Figs 1I, D, E and L). All
components expressed potent insecticidal activity individually
against S. pyrioides (Table 2, Fig. 1). From the hundreds of essential
oils and compounds that were tested for another project against
S. pyrioides, essential oils from cultivars of rose-scented geranium
were most toxic (Sampson BJ et al., unpublished). LD50 values of
300 ppm or less after the first hour of exposure of a compound
warrants further testing and possible commercialization of these
compounds. The monoterpene-rich essential oils from cultivars
of rose-scented geranium compare favorably with neem (an EPA-
registered biopesticide). Rose-scented geranium essential oil and
its individual components may prove useful in IPM programs as
new sources of agrichemicals against lace bugs and other similar
small arthropod pests.
Pest Manag Sci 2013; 69: 1385 –1392 c
2013 Society of Chemical Industry
1390 Abbas Ali et al.
Table 2. Toxicity of five rose-scented geranium essential oils, eight pure compounds and two commercial insecticides against the adult azalea lace
bug, Stephanitis pyrioides
rankingaNSlope (±SE) LD50 (95% CI)bχ2P-value
Geraniol 1 10 5.55 (0.28) 200 (3– 490) 380.59 <0.0001
Citral 1 10 4.82 (0.22) 380 (10 –790) 485.37 <0.0001
Citronellol 1 15 4.50 (0.17) 250 (10– 560) 687.56 <0.0001
Nerol 1 10 4.47 (0.20) 300 (0– 980) 512.65 <0.0001
‘Bourbon’ oil 1 10 4.74 (0.21) 650 (20–1110) 486.83 <0.0001
‘China’ oil 1 10 4.24 (0.19) 580 (200–870) 518.84 <0.0001
Geranic acid 2 8 3.61 (0.16) 2300 (1430–3270) 481.54 <0.0001
‘Egypt’ oil 2 10 3.41 (0.15) 880 (350– 1380) 488.26 <0.0001
‘Robers’ oil 3 10 3.13 (0.15) 680 (120–1230) 453.70 <0.0001
Neem insecticidec3 10 2.83 (0.18) 3310 (2130– 5090) 251.01 <0.0001
trans-Nerolidol 4 10 2.64 (0.17) 2870 (1280– 4020) 235.34 <0.0001
Linalool 5 10 2.32 (0.13) 1720 (1150– 2450) 316.77 <0.0001
Citronellyl formate 5 10 1.99 (0.13) 2330 (1000– 5250) 246.02 <0.0001
Malathion insecticidec
,d6 25 0.00 (0.00) 10 000e——
‘Frensham’ oil 7 10 1.62 (0.16) 19 750 (12 560 – 50 200) 102.4 <0.0001
logedose 3920 1.05 (0.04) 667.15 <0.0001
Exposure time 3920 0.63 (0.03) 550.24 <0.0001
aInsect toxicity rankings based on Tukey’s HSD (P<0.05, 1: highly active, 7: least active).
bEstimates of LD50 is in ppm.
cMalathion and neem were used as positive controls.
dMalathion serves as a baseline control to compare the bioactivity of essential oils and compounds.
eConfidence intervals not achieved in the given range of doses because estimated LD50 of malathion occurs at a dose >10 000 ppm.
3.3 Mosquito larvicidal bioassays
The toxicity of major compounds of rose-scented geranium
essential oil against one-day-old larvae of Ae. aegypti is given
in Table 3. The trans-nerolidol, with an LD50 value of 13.4 ppm, was
the most toxic compound against Ae. aegypti larvae, followed by
geraniol (49.3 ppm), citronellol (49.9 ppm) and geranyl formate
(58.5 ppm). ()-Linalool, geranic acid and citronellyl formate
showed about 50% mortality at the highest dose of 100 ppm,
malathion insecticide
citronellyl formate
Conc entration (% oil)
1 h exp
3 h exp
5 h exp
'Bourbon' oil
S. pyrioides
mortality (% ± SE)
'China' oil
'Frensham' oil
'Egypt' oil
geranic acid
neem insecticide
Dose (ppm)
'Rober's Lemon Rose' oil
7,500 10,0005,0002,5000 7,500 10,0005,0002,5000 7,500 10,0005,0002,5000 7,500 10,0005,0002,5000 7,500 10,0005,0002,5000
Figure 1. Mortality of adult azalea lace bug, Stephanitis pyrioides, treated with rose-scented geranium essential oils and its pure compounds after 1 h ( ),
3h( )and5h( )ofexposure. c
2013 Society of Chemical Industry Pest Manag Sci 2013; 69: 1385 –1392
Insecticidal and biting deterrent activity of rose-scented geranium
Figure 2. Biting deterrence index (BDI) of the essential oils extracted from samples of rose-scented geranium cultivars collected from various parts of the
world against female Ae. aegypti. Ethanol was the solvent control and DEET at 4.8 µgcm
2was used as positive control.
Figure 3. Mean BDI values for pure compounds isolated from various
cultivars of rose-scented geranium essential oils against female Aedes
while citral and isomenthone did not show any larvicidal activity
against Ae. aegypti in screening bioassays.
3.4 Mosquito biting bioassays
BDI values of oils extracted from the samples of rose-scented
geranium collected from various countries are given in Fig. 2.
Rose-scented geranium cultivar ‘Egypt’ essential oil at 100 µgcm
with a BDI value of 0.8 showed highest biting deterrent activity,
followed by cultivars ‘Frensham’ (BDI =0.76), ‘China’ (BDI =0.72),
‘Rober’s Lemon Rose’ (BDI =0.63) and ‘Bourbon’ (BDI =0.45). BDI
values at 10 µgcm
2dose were similar to 100 µgcm
2in the
essential oils tested, except for cultivars ‘China’ and ‘Frensham’,
Table 3. Toxicity of major compounds of rose-scented geranium
essential oil against one-day-old larvae of Aedes aegypti
Compound LD50 (95% CI)aLD90 (95% CI)aχ2df
Geranyl formate 58.5 (50.4 –69.5) 138.2 (108 –203) 60.4 38
Geraniol 49.3 (40–62.40) 94.1 (72 –157.7) 28.1 38
Citronellol 49.9 (39.1– 59.5) 95.2 (73.5 –150.9) 34.8 38
trans-Nerolidol 13.4 (12 –15) 21.5 (18.6–26.6) 59.4 38
()-Linalool >100b
Citral —c
Geranic acid >100
Citronellyl formate >100
Isomenthone —
aLD50 and LD90 values are given in ppm.
bThe compound gave 50% mortality at 100 ppm in screening.
cCompounds did not show any larvicidal activity at 100 ppm.
where the activity was significantly higher at 100 µgcm
values for major compounds present in rose-scented geranium
essential oils are given in Fig. 3. Geranic acid showed highest
biting deterrent activity (BDI =0.99), which was not statistically
different from DEET. Geranyl formate with a BDI value of 0.63 was
the second most active compound, while the activity for each of
the remaining test compounds was much lower and near that of
the solvent control.
In conclusion, this is the first report on the insecticidal activity of
essential oils of rose-scented geranium against adult azalea lace
bug and mosquitoes. This is also the first report on the biting
Pest Manag Sci 2013; 69: 1385 –1392 c
2013 Society of Chemical Industry
1392 Abbas Ali et al.
deterrent activity of rose-scented geranium essential oils and their
pure compounds. The rose-scented geranium essential oils and
pure compounds from this study have shown promising results as
insecticides, which warrants further research to establish them as
potential biopesticides. One of the pure compounds, geranic acid,
showed highest biting deterrent activity, which was statistically
similar to that of DEET. Further research, through intensive in
vivo bioassays, is needed to explore the possibility of using this
compound as a deterrent/repellent in human protection.
This study was supported in part by USDA/ARS grant No. 56-
6402-1-612 and a grant from the Deployed War-Fighter Protection
(DWFP) Research Program, the US Department of Defense, through
the Armed Forces Pest Management Board (AFPMB). Thanks to
Dr David Bradshaw for providing space in the Heirloom Garden,
and to Dr Melissa Riley for help. Thanks also to the Department
of Entomology, Soils and Plant Sciences at Clemson University for
their support of this research. The authors are grateful to Dr James
J Becnel, Mosquito and Fly Research Unit, Center for Medical,
Agricultural and Veterinary Entomology, USDA-ARS, Gainesville,
Florida, for supplying Ae. aegypti eggs.
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... As such, it was recently produced in a transgenic maize plant to control fungal disease outbreak (Yang et al., 2011). Geranate also has potential as insecticide since it possesses excellent insecticidal activity against Stephanitis pyrioides and Aedes aegypti as well as high biting deterrent activity (Ali et al., 2013). Moreover, geranate is known to be a tyrosinase inhibitor and inhibits melanin synthesis (Wang & Hebert, 2006) in applications of skin depigmentation. ...
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Isoprenoids are a large family of natural products with diverse structures, which allow them to play diverse and important roles in the physiology of plants and animals. They also have important commercial uses as pharmaceuticals, flavouring agents, fragrances, and nutritional supplements. Recently, metabolic engineering has been intensively investigated and emerged as the technology of choice for the production of isoprenoids through microbial fermentation. Isoprenoid biosynthesis typically originates in plants from acetyl-coA in central carbon metabolism, however, a recent study reported an alternative pathway, the Isopentenol Utilization pathway (IUP), that can provide the building blocks of isoprenoid biosynthesis from affordable C5 substrates. In this work, we expressed the IUP in Escherichia coli to efficiently convert isopentenols into geranate, a valuable isoprenoid compound. We first established a geraniol-producing strain in E. coli that uses the IUP. Then, we extended the geraniol synthesis pathway to produce geranate through two oxidation reactions catalysed by two alcohol/aldehyde dehydrogenases from Castellaniella defragrans . The geranate titer was further increased by optimizing the expression of the two dehydrogenases and also parameters of the fermentation process. The best strain produced 764 mg/L geranate in 24 h from 2 g/L isopentenols (a mixture of isoprenol and prenol). We also investigated if the dehydrogenases could accept other isoprenoid alcohols as substrates.
... Previously, trans-nerolidol was reported as an effective larvicide while it showed lowest repellency against Ae. aegypti, although the tested dose of trans-nerolidol as repellent was not clearly mentioned (Ali et al. 2013). In current study, caryophyllene and trans-nerolidol were evaluated singly at three different doses 330 μg/cm 2 , 165 μg/ cm 2 , and 33 μg/cm 2 while the mixture of both constituents examined only at 330 μg/cm 2 against Ae. ...
Disease vectoring mosquitoes are a serious threat to humans. However, till today only few mosquito repellents have been identified. The current study was conducted to evaluate the repellent potential of Carpesium abrotanoides essential oil against Aedes aegypti females by human bait technique. Essential oil was extracted by steam distillation process while the identification of chemical constituents was carried out by gas chromatography–mass spectrometry. Time span repellent bioassays of C. abrotanoides essential oil in comparison to DEET were performed at three different doses (33 μg/cm2, 165 μg/cm2, and 330 μg/cm2) under laboratory conditions. Highest repellency periods for essential oil and DEET were observed at the tested dose of 330 μg/cm2 with 315 min and 720 min, respectively. Lowest repellency period of 45 min for essential oil and 105 min for DEET was recorded at the tested dose of 33 μg/cm2. Major constituents caryophyllene (24.3%) and trans-nerolidol (12.0%) of C. abrotanoides essential oil were also evaluated as repellents at three different doses (330 μg/cm2, 165 μg/cm2, and 33 μg/cm2) against Ae. aegypti. Surprisingly, trans-nerolidol completely inhibited Ae. aegypti landings for 45 min when tested at 330 μg/cm2. However, caryophyllene did not completely inhibit Ae. aegypti landing even after immediate application at the tested dose of 330 μg/cm2. At the tested dose of 330 μg/cm2, the mixture (trans-nerolidol + caryophyllene) completely inhibited Ae. aegypti landing for 60 min indicating the synergistic effect of caryophyllene. Hence, C. abrotanoides as well as its major constituent, especially trans-nerolidol, have potential to formulate as mosquito repellent comparable of DEET.
... These results were similar to those using Tween-80 (1%), while for the positive control (Diazinon 2%), larval mortality was 97-100% in both species. Ríos et al. (2017) that GO can affect the metabolism and physiology of insects (Ali et al. 2013;Gallardo et al. 2015); for example, by producing neurotoxic effects through the inhibition of acetylcholinesterase (AChE) (Mills et al. 2004;Rattan 2010). However, in some cases, gene mutations can cause structural changes to the AChE enzyme, leading to decreased sensitivity to biopesticides (Li et al. 2010) and possibly resulting in greater quantities of EO being required to produce similar pesticidal effects in different insect species. ...
We conducted laboratory experiments to investigate the repellent and insecticidal activity of Pelargonium graveolens geranium oil (GO) against larvae and adults of two dipteran species Musca domestica and Lucilia cuprina. The insecticidal activity of the GO was assessed on larvae using an immersion test, and on adults using impregnated filter paper and direct surface contact tests. Meanwhile, the repellent activity of the GO was assessed against adults of the two fly species. The results showed that P. graveolens GO had no larvicidal activity against both dipteran species. The lethal concentrations (LC50) of GO after 15 min exposure were 3.0% and 2.5% in the direct surface application test, and 5.9% and 3.5% in the filter paper test, for M. domestica and L. cuprina, respectively. The GO of P. graveolens showed a repellent effect at a concentration of 1%. Our results suggest that P. graveolens GO has potential as a biopesticide for the control of M. domestica and L. cuprina and could provide an alternative to chemical insecticides.
... Their results revealed insecticidal and growth inhibitory potential of Coumarin against red palm weevil larvae [20,21]. Insecticidal potential of sesquiterpenes (an important class of terpenes comprising three isoprenes) is well known against other pest species, including Aedes aegypti, Coptotermes formosanus, Dermacentor variabilis, Musca domestica, Nilaparvata lugens, Pediculus capitis, Periplaneta americana, Sitophilus zeamais, S. oryzae, Stephanitis pyrioides, and Tribolium castaneum [22][23][24][25][26][27][28]. Surprisingly, there has not been a single study on the insecticidal potential of sesquiterpenes against red palm weevils. ...
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Natural biopesticide development for invasive populations of red palm weevils is mainly responsible for the destruction of date palms and demands an extensive screening program of plant secondary metabolites. In the current study, the pesticidal potential of sesquiterpenes (C15 H24), an important class of plant secondary metabolites primarily composed of three isoprene units, was evaluated by laboratory toxicity, feeding performance bioassays, and host detoxification gene expression patterns. Dose-mortality response bioassays performed against mid-aged eighth-instar red palm weevil larvae revealed dose-dependent mortality. Only three sesquiterpenes, including Farnesol (LD50 = 6559 ppm) and Farnesyl acetate (LD50 = 7867 ppm), are considered to have significant toxicity, with Picrotoxin (LD50 = 317 ppm) being the most toxic. Furthermore, highly toxic sesquiterpene (Picrotoxin) established in the current study tremendously reduced the feeding performance indices, including the efficacy of conversion of digested food (ECD) (81.74%) and the efficacy of conversion of ingested food (ECI) (73.62%). The least toxic sesquiterpenes, including β-Caryophyllene, (+)-Cedrol, Nerolidol, (+)-Nootkatone, and Parthenolide, observed in the current study failed to impart significant reductions of ECI and ECD indices. Lethality of the least toxic sesquiterpenes was overcome by greatly inducing gene expressions of Glutathione S transferase (GST) and Cytochrome P450. These encouraging results enabled us to suggest Picrotoxin as a promising biopesticide for the control of red palm weevil infestations.
Rose-scented geranium (Pelargonium graveolens L'Herit. ex Aiton), belonging to the family Geraniaceae, has gained considerable attention because of its fragrance and high economic value. The compositional complexity of rose-scented geranium essential oil (GEO) has been challenging for quality control. In this study, the chemical profiles of GEOs extracted from Indian cultivars/genotypes were developed using polarity-based fractionation, followed by characterization using a combination of gas chromatography (GC-FID), gas chromatography-mass spectrometry (GC-MS), and nuclear magnetic resonance spectroscopy (NMR). The analysis led to the identification of 121 compounds. Major components of the GEOs were citronellol (22.4–42.2 %), geraniol (5.7–30.5 %), linalool (2.1–9.8 %), citronellyl formate (4.0–9.5 %), isomenthone (5.3–7.5 %), geranyl formate (2.0–5.1 %), 6,9-guaiadiene (0.0–4.3 %), 10-epi-γ-eudesmol (0.2–6.4 %), 2-phenyl ethyl tiglate (1.0–2.1 %), geranyl tiglate (1.4–2.7 %), germacrene D (0.8–1.7 %) and geranial (0.4–1.6 %). This study identified effective markers which could help determine the authenticity of Indian cultivars/genotypes. Physical properties and chromatographic profiles of GEOs and terpeneless GEOs (TLOs) derived from Indian cultivar/genotype were compared. The two-step chromatographic separation coupled with principal component analysis allowed the identification of possible markers. The presence or absence of the sesquiterpenes, namely 10-epi-γ-eudesmol, 6,9-guaiadiene, and some other minor constituents, physical, and organoleptic properties, could effectively distinguish and define the quality of Indian cultivars/genotypes. Besides, the GEOs and TLOs prepared from different cultivars exhibited significant antimicrobial activity against Staphylococcus aureus and Candida albicans.
The diamondback moth (DBM), Plutella xylostella (L.), is a globally destructive pest of cruciferous vegetables. Excessive use of synthetic pesticides to control this species results in negative effects on the environment, human health, and nontargeted organisms. The essential oils (EOs) derived from plants may be developed as effective alternatives to conventional pesticides. In this study, thirteen EOs were extracted by hydrodistillation, respectively. Their chemical compositions were identified by gas chromatography-mass spectrometry (GC-MS). Furthermore, the biological activities of EOs such as toxicity, antifeedant activity, and growth inhibition effect, toward DBM larvae were investigated. Against DBM second-instar larvae, the most toxic EO was Pelargonium graveolens (LC50 = 0.36 μg/μl) after 72 hr of exposure, followed by Polygonum hydropiper (LC50 = 0.53 μg/μl). The Ocimum basilicum EO exhibited the highest antifeedant effect to third-instar larvae at at all set concentrations. At 15 μg/μl, the EOs of Acorus calamus, O. basilicum, and P. graveolens completely inhibited the feeding activities of larvae (100%). The Ruta graveolens EO showed the lowest relative growth rate and the highest growth inhibition rate towards third-instar larvae at diverse concentrations. And the EOs of P. hydropiper, A. calamus, and O. basilicum showed promising growth inhibition activities. Overall, the five EOs (P. graveolens, O. basilicum, R. graveolens, P. hydropiper, and A. calamus) showed moderate to high bioactivity, whereas eight EOs were found to be less active against DBM larvae. These results indicate that the five tested EOs are promising to be developed as novel botanical insecticides to control DBM population.
Apiaceae is a family encompassing medicinal and aromatic plants. They produce essential oils (EOs) inside oil canals, known as ducts and vittae, which occur in their vegetative and reproductive organs. Given the high EO yields and the availability of raw material from cultivations widespread all over the world, Apiaceae are exploitable for different industrial applications. An interesting perspective is their utilization in the fabrication of botanical insecticides effective against insect vectors of public importance such as mosquitoes, aiming to be eco-friendly alternatives to synthetic insecticides. On this basis, in the current review, we collected scientific evidence supporting the use of Apiaceae EOs and their major constituents as active ingredients in insecticidal formulations against larvae and adults of several mosquitoes that are important pathogen vectors (e.g., Anoph-eles, Aedes and Culex species). For this purpose, we analysed the published data on their larvicidal, ovicidal, oviposition deterrent, pupicidal, adulticidal, and repellent effects, using efficacy thresholds as in the case of larvicidal activity (LC 50 (lethal concentration killing 50 % of the exposed population) < 50 ppm). Toxicity to non-target organisms, including vertebrates, has also been reviewed. The major EO constituents have been highlighted, each with its spectrum of mosquitocidal activity, providing insights on their multiple modes of action. The urgent need to develop highly stable micro/nano-formulations for real-world use has been outlined. Current weaknesses and strengths in the steps toward the development of botanical insecticides have been analysed to increase awareness of the future challenges necessary to open the doors to the industrial utilization of Apiaceae EOs by agrochemical companies.
Laboratory experiments were conducted to investigate the possible nematicidal effect of the four terpenes, carvacrol, geraniol, eugenol and thymol, against the stem and bulb nematode Ditylenchus dipsaci (Kühn, 1857) Filipjev, Proceedings of the Helminthological Society of Washington, 3, 80–82, 1936, isolated from infested garlic cloves. In in vitro tests the observed nematicidal activity of terpenes in descending order was carvacrol > eugenol > geraniol > thymol. Carvacrol exhibited the highest activity of 100% mortality when it was tested at the concentration of 2000 μl/L. No synergistic action was recorded when all four terpenes were used in mixture. In soil experiments thymol showed the highest nematicidal activity amongst all the other terpenes followed by carvacrol. Our results indicate that there is a positive correlation between the concentration and the exposure time. In addition, increasing the dose of each terpene increased paralysis rates of the nematode were recorded. These results strongly show the nematicidal activity of terpenes, but further studies are needed to ascertain their mode of action against nematodes.
Thymus alternans and Teucrium montanum subsp. jailae are medicinal and aromatic plants, typical of Slovakian flora, producing bioactive essential oils. In the present study, we evaluated the insecticidal potential of the essential oils, obtained by hydrodistillation from the plant aerial parts and analysed by GC-MS, as insecticidal agents. For the purpose, they were assayed against three insect species acting as agricultural pests or vectors of medical relevance, such as the common housefly, Musca domestica L., the lymphatic filariasis vector, Culex quinquefasciatus and the Egyptian cotton leafworm Spodoptera littoralis; α-cypermethrin was tested as positive control. The two essential oils exhibited a different chemical profile, with monoterpenes and sesquiterpenes being the main fractions in the essential oils from Th. alternans and T. montanum subsp. jailae, respectively. Insecticidal tests showed that the T. montanum essential oil was effective against S. littoralis (LD50(90) = 56.7 (170.0) μg larva−1) and Cx. quinquefasciatus larvae (LC50(90) = 180.5 (268.7) mg L−1), whereas T. alternans essential oil displayed good toxicity against M. domestica adults (LD50(90) = 103.7 (183.9) μg adult−1). Overall, our results add useful knowledge about the potential of Slovakian flora as a source of botanicals for the eco-friendly management of insect pests and vectors.
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Annonaceous acetogenins extracted from the paw paw tree [Asimina triloba (L.) Dunal] are natural pesticides, and patents have been granted for their development as commercial pesticides. Their primary mode of action is the disruption of cellular respiration, which explains their broad-spectrum bioactivity against at least 15 species of arthropods and nematodes. Acetogenins (2000 ppm) dissolved in a 9.5% ethanol extract were highly bioactive against green peach aphids, Myzus persicae (Sulzer), rapidly killing 100% of nymphs and apterous adults, faster than the microbial-based insecticide, spinosad. The extract and spinosad were equally effective at inducing mortality for larval blueberry gall midges, Dasineura oxycoccana (Johnson). Toxicity of acetogenins compared favorably to malathion and topical applications were also more effective than phosmet for knocking down aphids and gall midges of varying ages. New classes of pesticides, like Annonaceous acetogenins, are needed to replace or supplement organophosphate and carbamate insecticides in IPM programs. The acetogenins are unusual among many natural insecticides in that they have broad pesticidal activity, induce rapid mortality, and have a complex mode of action that helps to thwart insecticidal resistance.
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In this study we evaluated the biting deterrent effects of a series of saturated and unsaturated fatty acids against Aedes aegypti (L), yellow fever mosquito (Diptera: Culicidae) using the K & Dbioassay module system. Saturated (C6:0 to C16:0 and C18:0) and unsaturated fatty acids (C11:1 to C14:1, C16:1, C18:1, and C18:2) showed biting deterrence index (BDI) values significantly greater than ethanol, the negative control. Among the saturated fatty acids, mid chain length acids (C10:0 to C13:0) showed higher biting deterrence than short (C6:0 to C9:0) and long chain length acids (C14:0 to C18:0), except for C8:0 and C16:0 that were more active than the other short and long chain acids. The BDI values of mid chain length acids (C10:0 to C13:0) were not significantly less than N, N-diethyl-meta-toluamide (DEET), the positive control. Among the unsaturated fatty acids, C11:1 showed the highest activity (BDI = 1.05) and C18:2 had the lowest activity (BDI = 0.7). In C11:1, C12:1, and C14:1 BDI values were not significantly less than DEET. After the preliminary observations, residual activity bioassays were performed on C11:0, C12:0, C11:1, and C12:1 over a 24-h period. All the fatty acids (C11:0, C12:0, C11:1, and C12:1) and DEET showed significantly higher activity at all test intervals than the solvent control. At treatment and 1-h posttreatment, all fatty acids showed proportion not biting (PNB) values not significantly less than DEET. At 3-, 6-, and 12-h posttreatment, all fatty acids showed PNB values significantly greater than DEET. At 24-h posttreatment, only the PNB value for C12:0 was significantly higher than DEET. The dose-responses of C12:0 and DEET were determined at concentrations of 5-25 nmol/cm2. As in the residual activity bioassays, the PNB values for C12:0 and DEET at 25 nmol/cm(2) were not significantly different. However, at lower concentrations, the PNB values for C12:0 were significantly greater than DEET. These results clearly indicate that mid chain length fatty acids not only have levels of biting deterrence similar to DEET at 25 nmnol/cm(2) in our test system, but also appeared to be more persistent than DEET. In contrast, in vivo cloth patch assay system showed that the mid-chain length fatty acids, C11:0, C11:1, C12:0, and C12:1 had minimum effective dose (MED) values greater than DEET against Ae. aegypti and their relative repellency varied according to species tested. The MED values of 120 (C11:0), 145 (C12:0) and 116 (C11:1) nmol/cm(2) against Anopheles quadrimaculatus Say, indicated that these acids were not as potent as DEET with a MED of 54 nmol/cm(2). The MED ratio of the C11:0 and C11:1 for all three mosquito species indicated the C11 saturated and unsaturated acids as more repellent than their corresponding C12:0 and C12:1 homologues.
Geranium oil is one of the most frequently used oils in aromatherapy. However, there is a large and diverse variation in the composition of commercial geranium oil, which depends only partly on its country of origin. The bioactivity of 16 commercial samples of geranium oils was assessed in vitro against 25 different bacteria, 20 Listeria monocytogenes strains and 3 filamentous fungi; the antioxidant and pharmacological effect was also studied and the results correlated against the chemical composition. The results show that the wide variability in bioactivity between samples cannot be directly correlated with the country of origin nor the main chemical components. This suggests that the many different paramedical effects of geranium oil, which are accredited to geranium oil regardless of its chemical composition, may be due to its action as an odor through the limbic system.
The volatile flower oils of three genotypes of rose-scented geranium (Pelargonium sp.) commercially cultivated at a high altitude (2200 m above MSL) location (Kodaikanal) in India were investigated by GC and GC–MS. Freshly collected flowers of genotypes 1, 2 and 3 on distillation produced oil yields of 0.32%, 0.34% and 0.50%, respectively. The flower oil of genotype 1 was richer in α-pinene (1.7%), (Z) and (E)-rose oxides (1.3% and 0.6%), isomenthone (6.8%), citronellol (43.8%), citronellyl formate (20.4%), citronellyl acetate (1.0%), β-caryophyllene (2.6%), citronellyl butyrate (2.1%) and citronellyl tiglate (1.9%). The flower oil of genotype 2 was richer in terpinen-4-ol (1.3%), geranyl formate (3.6%), β-bourbonene (1.2%), α-muurolene (1.3%), geranyl isovalerate (0.9%), 10-epi-γ-eudesmol (4.6%) and geranyl tiglate (2.9%). The flower oil of genotype 3 was richer in linalol (7.6%), geraniol (38.6%), geranyl acetate+geranic acid (5.2%), β-phenylethyl butyrate (4.6%), 6,9-guaiadiene (2.3%) and α-humulene (1.5%). Copyright © 2000 John Wiley & Sons, Ltd.
The terms "attractant" and "repellent" only have commonly Been employed to describe chemicals in terms of their effect on the behavior of insects. The two terms as defined in their strictest sense do not apply to all possible types of reactions of insects to chemicals. There is a genuine need to clarify the use of terminology in this subject. An analysis of the behavioral effects of chemicals on locomotion, feeding, and oviposition has led to the designation and definition of five terms; namely, arrestant, stimulant (locomotor, feeding, ovipositional),attractant, repellent, deterrent. It is proposed that these five be employed as standard terms within the limits of the definitions given.
The essential oils of two scented geranium (Pelargonium spp.) cultivars grown on Reunion Island were investigated by GC–MS. The specific odour attributes of each single constituent were correlated with the olfactory impression of the two essential oils. The scent of the essential oil extracted from the well-known rose-scented geranium cultivar, Pelargonium cv. Rosé, is based on the rosy, fruity, minty and faintly citrusy aromas of the main components, citronellol (21.9%), geraniol (18.3%), linalool (16.0%), citronellyl formate (11.6%) and isomenthone (7.6%), accompanied by minor compounds of olfactory significance, including geranyl formate (4.0%), nerol (1.7%), geranyl tiglate (1.6%) and neryl propanoate (1.5%) in particular. The volatile constituents of the essential oil of a second geranium cultivar (Pelargonium sp.) are dominated by monoterpene hydrocarbons, of which the most abundant is p-cymene (35.8%). This oil possesses a very unusual, although very pleasant, ‘citrusy-peppery-spicy’ and herbaceous scent, somewhat pungent, which is rather reminiscent of thyme. Chemotaxonomic considerations about the genus Pelargonium are also discussed. Copyright © 2004 John Wiley & Sons, Ltd.