Tomato-produced 7-epizingiberene and R-curcumene act as repellents to whiteflies

Article abstract of DOI:10.1016/j.phytochem.2010.10.014

How whiteflies (Bemisia tabaci) make the choice for a host plant prior to landing, is not precisely known. Here we investigated whether they respond to specific volatiles of tomato. Zingiberene and curcumene were purified from Solanum habrochaites (PI1278

Full text of DOI:10.1016/j.phytochem.2010.10.014

Phytochemistry 72 (2011) 68–73
Contents lists available at ScienceDirect
Phytochemistry
journal homepage: www.elsevier.com/locate/phytochem
Tomato-produced 7-epizingiberene and R-curcumene act as repellents to whiteflies
b
a
c
c
d
Petra M. Bleeker a,b, , Paul J. Diergaarde , Kai Ament , Stefan Schütz , Bettina Johne , Jan Dijkink ,
Henk Hiemstra d, René de Gelder e, Michiel T.J. de Both b, Maurice W. Sabelis f, Michel A. Haring a,
Robert C. Schuurink a
⇑
a University of Amsterdam, Dept. of Plant Physiology, Science Park 904, 1098 XH, Amsterdam, The Netherlands
b Keygene NV, Agrobusiness Park 90, P.O. Box 216, 6700 AE, Wageningen, The Netherlands
c University of Göttingen, Dept. of Forest Zoology and Forest Conservation, Buesgenweg 3, 37077 Göttingen, Germany
d University of Amsterdam, Dept. of Synthetic Organic Chemistry, Nieuwe Achtergracht 129, 1018 WS, Amsterdam, The Netherlands
e Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
f University of Amsterdam, Institute for Biodiversity and Ecosystem Dynamics, Science Park 904, 1098 XH, Amsterdam, The Netherlands
a r t i c l e i n f o
a b s t r a c t
Article history:
How whiteflies (Bemisia tabaci) make the choice for a host plant prior to landing, is not precisely known.
Here we investigated whether they respond to specific volatiles of tomato. Zingiberene and curcumene
were purified from Solanum habrochaites (PI127826), characterised by NMR and X-ray analysis and iden-
tified as 7-epizingiberene and R-curcumene. In contrast, oil from Zingiber officinalis contained the stereo-
isomers zingiberene and S-curcumene, respectively. Using a combination of free-choice bio-assays and
electroantennography, 7-epizingiberene and its dehydrogenated derivative R-curcumene were shown
to be active as semiochemicals to B. tabaci adults, whereas the stereoisomers from ginger were not. In
addition, R-curcumene elicited the strongest electroantennographic response. Bio-assays showed that a
cultivated tomato could be made less attractive to B. tabaci than its neighbouring siblings by the addition
of the tomato stereoisomer 7-epizingiberene or its derivative R-curcumene. These sesquiterpenes appar-
ently repel adult whiteflies prior to landing, presumably because it informs them that after landing they,
or their offspring, may be exposed to higher and lethal concentrations of the same compounds.
Ó 2010 Elsevier Ltd. All rights reserved.
Received 15 July 2010
Received in revised form 20 September
2010
Available online 11 November 2010
Keywords:
Solanum lycopersicum
Solanum habrochaites
Whitefly
Plant volatiles
Host selection
7-Epizingiberene
R-Curcumene
Stereoisomer
Electroantennography
1. Introduction
consists of labial dabbing, probing and, finally, feeding, whereas
pre-landing responses to colour, especially yellow-green (wave-
By deciding which host plant to select for laying their eggs, fly-
ing adults of polyphagous insects determine a great deal of the
developmental success of their relatively less mobile offspring.
Here, we study these decisions for the case of the sweetpotato
whitefly, Bemisia tabaci Gennadius, a polyphagous insect, first de-
scribed as a plant pest in 1889 and continuing to be a threat to var-
ious horticultural and agricultural crops worldwide, mostly due to
vectoring various devastating plant viruses (Jones, 2003). Prior to
landing on a plant these insects may use a combination of vision
and olfaction, to scan for cues that inform them on plant quality
(Visser, 1988). Post-landing, they may also use gustatory or other
sensory and metabolic cues to perceive host quality and to decide
whether or not to oviposit. For B. tabaci post-landing behaviour
length 500–600 nm), have been described by van Lenteren and
Noldus (1990). Recently, we found that, in addition to visual cues,
whiteflies use semiochemicals for selecting a host plant from a dis-
tance. They display avoidance behaviour to a selection of tomato
terpenes, in particular the sesquiterpenes zingiberene and curcum-
ene (Bleeker et al., 2009). Tomato zingiberene is known to be toxic
and to have a negative effect on whitefly feeding and oviposition
(Freitas et al., 2002; Muigai et al., 2002); ginger oil, which contains
mostly zingiberene, has a similar impact (Zhang et al., 2004).
However, the repellency in response to these compounds has not
been elucidated so far.
In this study we isolated and purified zingiberene and curcum-
ene focussing on the effect of these sesquiterpenes on the initial
decision making process of whiteflies and addressed the following
questions: (a) whether B. tabaci antennae can perceive these
volatiles; (b) how specific perception is for different stereoisomers
purified from tomato and ginger and; (c) how different stereoiso-
mers influence whiteflies in deciding to land on a plant.
⇑
Corresponding author at: University of Amsterdam, Dept. of Plant Physiology,
Science Park 904, 1098 XH, Amsterdam, The Netherlands. Tel.: +31 20 5257850; fax:
+31 20 5257934.
E-mail address: p.m.bleeker@uva.nl (P.M. Bleeker).
0031-9422/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.phytochem.2010.10.014

P.M. Bleeker et al. / Phytochemistry 72 (2011) 68–73
69
(Bleeker et al., 2009), we decided to investigate the role of zingibe-
rene in the initial choice behaviour of whiteflies in more detail. To
this end, we first purified it from ginger (Zinger officinalis) oil,
which is very rich in zingiberene (Antonious and Kochhar, 2003)
and from leaves and stem material of the wild tomato PI127826
(Supplementary information). To determine the structure of the to-
mato and ginger zingiberene, both compounds were subjected to
NMR analysis. Comparison of the NMR-spectra with those given
by Breeden and Coates (1994) gave no absolute certainty about
the structure. However, both zingiberenes could be purified by
crystallisation of the Diels–Alder adduct, which made it possible
to obtain unambiguous structural evidence of stereochemistry at
carbons 4 and 7 by X-ray analysis (Supplementary information).
It substantiated that S. habrochaites contained 7-epizingiberene
(Breeden and Coates, 1994) whereas ginger oil contained its
diastereomer zingiberene. When exposed to air, GC–MS analyses
showed isolated zingiberene to spontaneously converted to cur-
cumene (data not shown). Indeed, controlled dehydrogenation of
both 7-epizingiberene and zingiberene resulted in pure R- and
S-curcumene, respectively (Supplementary information).
2. Results
When given a choice between cultivated tomato (Solanum
lycopersicum cv. Moneymaker) and wild tomato Solanum habrochaites
PI127826, more than 90% of the whiteflies choose cultivated toma-
to (Fig. 1a; P < 0.000). However, in a no-choice assay, approxi-
mately 60% of the whiteflies will still land on the wild tomato
(Fig. 1b), which is not significantly different from the numbers
found on the cultivated tomato (P = 0.267). On the wild tomato,
all whiteflies subsequently die (Fig. 1c), whereas >75% will survive
on the cultivated tomato indicating its suitability as a host (Fig. 1c).
Since the wild tomato PI127826 contains large amount of zing-
iberene and because zingiberene acts as repellent to whiteflies
Next, we assayed host preference in bio-assays with purified
7-epizingiberene or zingiberene applied to one of four different
S. lycopersicum cv. Moneymaker plants of the same age, size and col-
our. As expected, in the absence of zingiberene the four tomatoes
were equally attractive to B. tabaci (data not shown). Next, zingibe-
rene (10 lg) was administered on paper cards to one of the four
plants in the experimental setup. Zingiberene purified from ginger
oil did not appear to make plants repellent to B. tabaci as the per-
centage of recaptured B. tabaci on each of the four tomato plants
did not deviate significantly from an equal distribution (Fig. 2a;
P = 0.521). Applied at the same concentration, 7-epizingiberene
purified from tomato was very effective in reducing the number
of whitefly visitations (Fig. 2c). The percentage of whiteflies visit-
ing the plant with 7-epizingiberene decreased significantly
(P < 0.001), whereas the three control plants harboured increased
numbers of B. tabaci, as expected, although not in equal numbers.
Both curcumenes were subsequently tested in free-choice bio-as-
says to ascertain their effect on repellence as well. Clearly, B. tabaci
was only repelled by R-curcumene (Fig. 2b and d; P = 0.475 and
P < 0.001, respectively), the derivative of tomato 7-epizingiberene.
To assess whether the four compounds used in the bio-assays
are actually perceived by whitefly antennae, we employed electro-
antennography (Thakeow et al., 2008) on whitefly antennae by
puffing a dilution of the selected purified compounds over an iso-
lated antenna. Although each of the two stereoisoforms of zingibe-
rene, as well as each of the two enantiomers of curcumene,
appeared to elicit an electrical response in the antennae of white-
flies, R-curcumene consistently elicited the highest effect (Fig. 3a).
For that reason, R-curcumene was diluted further. Even at higher
dilution (10À4) whitefly antennae still responded to the presence
of this compound (Fig. 3b).
3. Discussion
When given no other option, whiteflies will find and settle on a
host displaying toxic properties, even if chances for survival are
poor, indicating that visual cues dominate the response under
the conditions of this assay (Fig. 1b and c). Since visual and odour
cues can interact when processed in the insect brain (Balkenius
et al., 2009), it is important to perform olfactory preference tests
against the same visual background. Our host-choice assays show
that, when given the choice between wild and cultivated tomato
the initial decision of most whiteflies is to settle on the cultivated
tomato (Fig. 1a). This is most likely due to the presence of zingibe-
rene and curcumene in the headspace of PI127826 (52.1 and
Fig. 1. Repellence and toxicity of PI127826. B. tabaci (a) preference 2 h after release
(as % of released B. tabaci, n = 100) in a choice assay on tomato plants; (b) presence
on tomato leaf (as % of total released, n = 100) in a no-choice assay (after 2 h); (c)
survival on tomato leaflet (as % of total released, n = 50) in a no-choice assay (after
48 h). Bars represent mean values of 5–8 replications (+SE). Different letters
represent statistically significant differences. Tomato plants used; S. habrochaites
(PI127826) and S. lycopersicum (cv. Moneymaker).

70
P.M. Bleeker et al. / Phytochemistry 72 (2011) 68–73
Fig. 2. Stereoisomer specific compounds can act as repellent to whiteflies. Treatment effect of the addition of 10 lg of (a) Z. officinalis zingiberene (b) Z. officinalis
S-curcumene, (c) S. habrochaites (PI127826) 7-epizingiberene (d) S. habrochaites R-curcumene (PI127826) added to one plant in a setup of four S. lycopersicum plants
(expressed as % of control setup with four untreated plants). Bars represent mean values of eight replications (+SE). nt: Plants in setup to which no volatiles were added. ns:
Non-significant effect, ***: P < 0.001.
Fig. 3. Electroantennographic responses of isolated B. tabaci antennae to purified compounds. EAG reponse to (a) 10À4 dilution of zingiberene, 7-epizingiberene, S-curcumene
and R-curcumene and (b) to a 10À4–10À6 dilution range of R-curcumene. Bars represent the mean values of P5 replications + SE. Different letters represent statistically
significant differences. Black bars represent responses to the application of odour standards of purified compounds in paraffin oil. Grey bars represent responses to the
application of paraffin oil only (background control).
28.2
l
g 24 hÀ1 gÀ1, respectively), which act as repellents to white-
an unsuitable one (e.g. Cook et al., 2007). Hence, by their associa-
tion with food quality of the host plant, the presence of toxic plant
compounds or even the danger from predators inhabiting the
plant, these compounds may convey information, and thus act as
genuine semiochemicals. The arthropods may either learn this
association first and upon subsequent perception of these semio-
chemicals, they may respond in a way that promotes their repro-
ductive success (adaptive learning; Egas and Sabelis, 2001;
Nomikou et al., 2003; van Wijk et al., 2008). Alternatively, they
do not require a learning experience and respond innately, as a
consequence of natural selection that acted many generations on
flies (Bleeker et al., 2009). Moreover, against a background of iden-
tical visual cues, specific sesquiterpenes repel whiteflies from a
plant which it would otherwise choose as a host (Fig. 2). Applying
10 lg of sesquiterpenoids in the bioassay should be within the
range of sesuiterpenes emitted by the wild tomato plants, although
it is not possible to measure the exact concentration in the exper-
imental setup. Our results prompted the question why and how
whiteflies are repelled by these compounds. In general, volatile
compounds released by plants may help phytophagous arthropods
to find a suitable host plant (e.g. Webster et al., 2008), or to avoid

P.M. Bleeker et al. / Phytochemistry 72 (2011) 68–73
71
the reproductive performance resulting from their olfactory and
behavioural response.
this pest to a plant or site where it can be killed (so called
push–pull strategies for pest control; Cook et al., 2007; Hassalani
et al., 2008).
Although we do not wish to exclude other possible functions of
7-epizingiberene and R-curcumene, such as a role in masking
attractive plant odours or signaling negative plant qualities other
than those directly related to the compounds themselves, the cur-
rently available evidence prompts us to hypothesise that whiteflies
(B. tabaci) are repelled at a distance from the tomato plant by the
sesquiterpenes R-curcumene and 7-epizingiberene, because it sig-
nals the presence of these compounds in toxic concentrations in
the plant. When given a choice between cultivated tomato and
the wild tomato, S. habrochaites (PI127826), whiteflies prefer not
to land first on the latter (Fig. 1a). In line with our hypothesis, this
specific wild tomato contains toxic levels of 7-epizingiberene in its
trichomes (Supplementary information, Weston et al., 1989).
When given no other choice than PI127826 leaves as a source of
food, B. tabaci will still settle on these leaves in absence of an alter-
native (Fig. 1b). However, we showed that it will not survive there
(Fig. 1c) in agreement with earlier reports on the toxic effects of, as
we now know, 7-epizingiberene (Weston et al., 1989; Maluf et al.,
2001; Eigenbrode et al., 1994; Freitas et al., 2002; Muigai et al.,
2002; de Azevedo et al., 2003). At a distance from the tomato plant,
this volatile compound (or its dehydrogenated form R-curcumene)
is present at low concentrations and, because it is not toxic at these
concentrations, it can provide information on the presence of that
compound at higher concentrations near or at the source. Thus, the
compound perceived at a distance provides reliable information on
the presence of toxic concentrations of a (related) compound on
this plant suggesting that is why it may trigger avoidance
behaviour of the whiteflies.
The repellent effect of zingiberene was shown to depend on ste-
reochemistry. Each of the two stereo-isoforms of zingiberene has
toxic effects on whiteflies and other herbivores after they come
into contact with these compounds (Eigenbrode et al., 1994; Freitas
et al., 2002; Zhang et al., 2004; Weston et al., 1989). However,
whiteflies can detect the presence of 7-epizingiberene (and R-cur-
cumene) prior to contact with the host plant and modify their
choice behaviour accordingly (Fig. 2). Since our whiteflies were
reared on cucumber, which does not contain any form of zingibe-
rene or curcumene, their response to 7-epizingiberene and R-cur-
cumene must be innate. Such an innate response to zingiberene
is apparently absent in whiteflies despite its severe toxicity. This
phenomenon of differential responses to stereo-isoforms is well
known from electroantennography with insects. Not only do many
plant metabolites exist in different stereo-isoforms with distinct
properties, they also occur in different plant species and their ef-
fects on insect receptors and neuronal discrimination between
enantiomers of volatile compounds differ with the insect species,
as shown for beetles (Wadhams et al., 1982), moths (Stranden
et al., 2002) and weevils (Wibe et al., 1998).
4. Concluding remarks
Besides dominant visual cues, B. tabaci makes use of volatile
semiochemicals prior to choosing a host. Only tomato-derived
7-epizingiberene and R-curcumene prompted a modified behaviour
in whiteflies under free-choice conditions, although their respective
stereoisomers, zingiberene and S-curcumene, from ginger elicited a
similar response in antennae, as determined by electroantennogra-
phy. Thus 7-epizingiberene and R-curcumene most likely signal the
presence of a hostile environment on the site of landing.
5. Experimental
5.1. General experimental procedures
A detailed description of the isolation of zingiberene, 7-epiz-
ingiberene, (S)-curcumene and (R)-curcumene can be found in
Supplementary information. In short; 7-epizingiberene 2 was isolated
from leaf and stem material of S. habrochaites (PI127826) by hex-
ane extraction of tissue ground in liquid nitrogen. The crude toma-
to plant extract was filtered with pentane over a plug of silica gel
from which almost pure (>90%) 7-epizingiberene was obtained.
This was dissolved in 10 ml tetrahydrofuran (THF) to which 4-phe-
nyl 1,2,4-trizoline-3,5-dione (PTAD; Fig. 4) was added dropwise
over 10 min. The reaction mixture was concentrated and purified
by flash chromatography to give a 4:1 mixture of isomers 1a and
1b (Fig. 4). After base hydrolysis, 7-epizingiberene was dehydroge-
nated by heating in benzene with palladium on carbon, as de-
scribed by Breeden and Coates (1994) to obtain (R)-curcumene 3.
This (R)-curcumene possessed 10–20% of a double bond isomer,
most probably 4 (see Supplementary information for NMR data).
The Diels–Alder adduct 1a could be purified by crystallisation,
which enabled X-ray analysis for unambiguous structural elucida-
tion of stereochemistry at carbons 4 and 7 (Fig. 4; CCDC 782570
contains the supplementary crystallographic data for this paper.
These data can be obtained free of charge via http://www.ccdc.
cam.ac.uk/conts/retrieving.html). Zingiberene was isolated from
ginger oil (Natura Sanat B.V., The Netherlands) as described by
Millar (1998). Ginger oil was kugelrohr distilled and reacted with
PTAD as described above. The reaction mixture was concentrated
and purified to give a colourless oil consisting of a 4:1 mixture
of diastereoisomers. After base hydrolysis, pure zingiberene was
obtained and after dehydrogenation and purification (S)-curcumene
was obtained.
5.2. Biological materials
Despite antennal responses to all four sesquiterpenes (Fig 3a),
whiteflies appear to be able to specifically differentiate between
the stereoisomers when locating tomato plants since only 7-epiz-
ingiberene and R-curcumene were repellent (Fig. 2). Because
zingiberene converts to curcumene in contact with air (Chen
and Ho, 1988), it might well be the compound that B. tabaci de-
tects most frequently at larger distances from the tomato plant.
Also, R-curcumene elicited a response in the antennae when
more diluted (Fig. 3b), suggesting that whiteflies can detect this
compound at a greater distance from the plant. Moreover, the re-
Tomato plants (S. lycopersicum, S. habrochaites) were grown in a
greenhouse compartment under controlled conditions (22–25 °C,
16/8 h photoperiod at 500 l
E mÀ2 sÀ1). A population of B. tabaci
(biotype Q) was collected from tomato in a greenhouse in Santa
María del Águila (Almería province, Spain) and reared in a clima-
tised chamber (Snijders, Tilburg; 28 °C, 16 h light 150 l ,
E mÀ2 sÀ1
RH 75%) on cucumber. For bio-assays adult whiteflies, males and
mated females alike, were randomly taken from the population
reared in the laboratory.
sponse at a dilution of 10À4 was only slightly lower than at 10À3
.
This extended range of detection points at the potential rele-
vance of this particular compound for long-range orientation
and host–plant finding. Hence, R-curcumene might be the most
effective compound to ‘push’ whiteflies away from the tomato
crop and to be used in combination with an attractant to lure
5.3. Bio-assays
No-choice and choice assays were carried out in a mesh cage
(1 m  1 m  1 m) inside
a closed greenhouse compartment

72
P.M. Bleeker et al. / Phytochemistry 72 (2011) 68–73
Fig. 4. Schematic representation of 7-epizingiberene purification.
(28 °C, RH 65%), with two potted, three-week old plants (either S.
lycopersicum cv. Moneymaker, or S. habrochaites PI127826) placed
in the middle of the cage. A total of 100 whiteflies was released
in the cage. After 2 h the number of whiteflies settled on the
plants was recorded. The test was repeated with two plants, now
1 S. lycopersicum C32 and 1 S. habrochaites PI127826 again with 100
whiteflies released in the mesh cage that were recaptured after 2 h.
Toxicity assays were performed in 0.5 l glass jars closed with
cheesecloth inside a climatised chamber. The fourth fully ex-
panded leaflet of a three-week old C32 or PI127826 was placed
at the bottom with the petiole wrapped in wet cotton wool covered
with aluminium foil. Carefully, 50 whiteflies were released in the
jar and survival was scored after 48 h.
Free choice experiments with B. tabaci were carried out in the
same greenhouse compartment, as described in detail by Bleeker
et al. (2009). In short, four potted, three-week old, tomato plants
(S. lycopersicum cv. Moneymaker) were placed in a square arrange-
ment with each plant at a distance of 75 cm from its neighbour in a
plastic-covered wooden tray filled with potting soil. The tray was
positioned in the centre of the greenhouse compartment. A total
of 150 adult whiteflies were captured from the rearing described
above, placed at 4 °C for 2 min and then released in the middle
of the setup. After 10 and 20 min from release the whiteflies were
recaptured and the number of whiteflies on each plant was re-
5.4. Electroantennographical assays
B. tabaci antennae were carefully dissected and used to record
electroantennographical (EAG) responses. EAGs were measured
by manual injection of the compound into a humidified stream
of air passing over the excised antenna mounted onto an antenna
holder housed in a polytetrafluoroethylene (Teflon) cell (flow rate
250 ml/min). Within this holder, the ends of the excised antennae
contacted a hemolymph electrolyte Ringer solution that provided
electrical contact to a pair of Ag/AgCl-electrodes (Thakeow et al.,
2008). The EAG potentials were amplified by a factor 100 using a
high impedance amplifier with a built-in low pass filter, set to a
cut-off frequency of 1 Hz. The amplified and filtered signal was dig-
itised using a 35900E A/D-converter (Agilent) and recorded by the
GC ChemStation software (Agilent) (Weißbecker et al., 2004).
Odour standards were produced from a dilution series of the
respective purified compounds in paraffin oil (Uvasol quality,
Merck/VWR). Small pieces of filter paper (2 cm2; Schleicher and
Schuell, Dassel, Germany) were soaked with 100 ll of the standard
dilution or paraffin oil only (control). The filter paper was put into a
10 ml glass syringe (Poulten and Graf GmbH, Wertheim, Germany).
Inside the air volume of the syringe, the odourant accumulated at a
concentration that depends on the concentration of the substance
in the solution and its vapour pressure as predicted by Henry’s law.
A reproducible stimulus could be supplied by puffing 5 ml of air
from the syringe over the antenna (Schütz et al., 1999). Dilutions
of the compounds were measured at least five times for their im-
pact on the response of at least five different whiteflies. Though
purified, we cannot exclude that compounds present in trace
amounts affected the AEG analysis. However, the whitefly antenna
in the experimental system could not be kept stable for a period
long enough to perform GC-AEG against a background of plant
headspace odour.
corded. To test the effect of a compound on repellence, 10 lg of a
purified sesquiterpene was applied to 10 filter paper discs (What-
man, 25 mm diameter) and attached to 1 of the 4 plants in the set-
up. The position of the treated tomato was randomised. Five
minutes after placing the volatiles on the plant, whiteflies were re-
leased. Discs with volatiles were always added to the same plant,
whereas the other plants received paper discs without the com-
pound under investigation. Prior to each assay with volatiles, the
choice experiment was done with the four plants untreated, in
the same spatial position, to establish a control value under the
same background, environmental conditions and arrangement.
For statistical comparison the non-treated setup was compared
to the treated setup. In the figures, the background attraction of
each plant in the untreated setup was set to 100%. Each experiment
was repeated eight times with new, inexperienced whiteflies and
with the same plants in altered positions. For each sesquiterpene
a new set of tomato plants was used.
5.5. Statistical analyses
The effect of addition of sesquiterpenes on response was tested
as the ratio between control and untreated by ANOVA using a
randomised complete block design, fitted including the effects of
plant and position and their possible interaction. Statistical analyses
for other choice and non-choice bio-assays and for the effect of

P.M. Bleeker et al. / Phytochemistry 72 (2011) 68–73
73
animal husbandry. Philos. Trans. Royal Soc. London. Ser. B: Biol. Sci. 363, 611–
621.
Jones, D.R., 2003. Plant viruses transmitted by whiteflies. Eur. J. Plant Pathol. 109,
195–219.
sesquiterpenes in the electroantennographical assays were car-
ried out using ANOVA. Values with P < 0.05 were regarded as
significant.
Maluf, W.R., Campos, G.A., Cardoso, M.G., 2001. Relationships between trichome
types and spider mites (Tetranychus evansi) repellence in tomatoes with respect
to foliar zingiberene content. Euphytica 121, 73–80.
Acknowledgements
Millar, J.G., 1998. Rapid and simple isolation of zingiberene from ginger essential oil.
J. Nat. Prod. 61, 1025–1026.
Muigai, S.G., Schuster, D.J., Snyder, J.C., Scott, J.W., Bassett, M.J., McAuslane, H.J.,
2002. Mechanisms of resistance in Lycopersicon germplasm to the whitefly
Bemisia argentifolii. Phytoparasitica 30, 347–360.
This work was supported by Senter Novem, Enza Zaden,
Vilmorin & Cie, Takii & Co., and De Ruiter Seeds.
Nomikou, M., Janssen, A., Sabelis, M.W., 2003. Herbivore host plant selection:
whitefly learns to avoid host plants that are unsafe for her offspring. Oecologia
136, 484–488.
Appendix A. Supplementary data
Schütz, S., Weissbecker, B., Koch, U.T., Hummel, H.E., 1999. Detection of volatiles
released by diseased potato tubers using a biosensor on the basis of intact insect
antennae. Biosens. Bioelectron. 14, 221–228.
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.phytochem.2010.10.014.
Stranden, M., Borg-Karlson, A.-K., Mustaparta, H., 2002. Receptor neuron
discrimination of the germacrene
armigera. Chem. Sens. 27, 134–152.
D enantiomers in the moth Helicoverpa
References
Thakeow, P., Angeli, S., Weissbecker, B., Schütz, S., 2008. Antennal and behavioural
responses of the fungivorous insect Cis boleti to volatiles of its host fungus.
Chem. Sens. 33, 379–387.
Antonious, G.F., Kochhar, T.S., 2003. Zingiberene and curcumene in wild tomato. J.
Environ. Sci. Health Part B 38, 489–500.
Balkenius, A., Bisch-Knaden, S., Hansson, B., 2009. Interaction of visual and odour
cues in the mushroom body of the hawkmoth Manduca sexta. J. Exp. Biol. 212,
535–541.
van Lenteren, J.C., Noldus, L.P.J.J., 1990. Whitefly–plant relationships: behavioural
and ecological aspects. In: Gerling, D. (Ed.), Whiteflies: Their Bionomics, Pest
Status and Management. Intercept Ltd., Andover, UK.
Bleeker, P.M., Diergaarde, P.J., Ament, K., Guerra, J., Weidner, M., Schütz, S., de Both,
M.T.J., Haring, M.A., Schuurink, R.C., 2009. The role of specific tomato volatiles in
tomato–whitefly interaction. Plant Physiol. 151, 925–935.
van Wijk, M., De Bruijn, P.J.A., Sabelis, M.W., 2008. Predatory mite attraction to
herbivore-induced plant odors is not a consequence of attraction to individual
herbivore-induced plant volatiles. J. Chem. Ecol. 34, 791–803.
Breeden, D.C., Coates, R.M., 1994. 7-Epizingiberene,
a
novel bisabolene
Visser, J.H., 1988. Host-plant finding by insects: orientation, sensory input and
search patterns. J. Insect. Physiol. 34, 259–268.
Wadhams, L.J., Angst, M.E., Blight, M.M., 1982. Responses of the olfactory receptors
of Scolytus scolytus (F.) (Coleoptera:Scolytidae) to the stereoisomers of
4-methyl-3-heptanol. J. Chem. Ecol. 8, 477–492.
sesquiterpene from wild tomato leaves. Tetrahedron 50, 11123–11132.
Chen, C.C., Ho, C.T., 1988. Gas-chromatographic analysis of volatile components of
ginger oil (Zingiber officinale Roscoe) extracted with liquid carbon-dioxide. J.
Agric. Food Chem. 36, 322–328.
Cook, S., Khan, Z., Pickett, J., 2007. The use of push–pull strategies in integrated pest
management. Annu. Rev. Entomol. 52, 375–400.
Webster, B., Bruce, T., Dufour, S., Birkemeyer, C., Birkett, M., Hardie, J., Pickett, J.,
2008. Identification of volatile compounds used in host location by the black
bean aphid, Aphis fabae. J. Chem. Ecol. 34, 1153–1161.
Weißbecker, B., Holighaus, G., Schütz, S., 2004. Gas chromatography with mass
spectrometric and electroantennographic detection: –analysis of wood odour
by direct coupling of insect olfaction and mass spectrometry. J. Chrom. A. 1056,
209–216.
de Azevedo, S.M., Faria, M.V., Maluf, W.R., Barnece de Oliveira, A.C., de Freitas, J.A.,
2003. Zingiberene-mediated resistance to the South American tomato pinworm
derived from Lycopersicon hirsutum var. hirsutum. Euphytica 134, 347–351.
Egas, M., Sabelis, M.W., 2001. Adaptive learning in a herbivorous mite. Ecol. Lett. 4,
190–195.
Eigenbrode, S.D., Trumble, J.T., Millar, J.G., White, K.K., 1994. Topical toxicity of
tomato sesquiterpenes to the beet armyworm and the role of these compounds
in resistance derived from an accession of Lycopersicon hirusutum f. typicum. J.
Agric. Food Chem. 42, 807–810.
Freitas, J.A., Maluf, W.R., Graças-Cardoso, M., Gomes, L.A.A., Bearzotti, E., 2002.
Inheritance of foliar zingiberene contents and their relationship to trichome
densities and whitefly resistance in tomatoes. Euphytica 127, 275–287.
Hassalani, A., Herren, H., Khan, Z.R., Pickett, J.A., Woodcock, C.M., 2008. Integrated
pest management: the push–pull approach for controlling insect pests and
weeds of cereals, and its potential for other agricultural systems including
Weston, P.A., Johnson, D.A., Burton, H.T., Snyder, J.C., 1989. Trichome secretions
composition, trichome densities, and spidermite resistance of ten accessions of
Lycopersicon hirsutum. J. Am. Soc. Hort. Sci. 114, 492–498.
Wibe, A., Borg-Karlson, A.K., Persson, M., Norin, T., Mustaparta, H., 1998.
Enantiomeric composition of monoterpene hydrocarbons in some conifers
and receptor neuron discrimination of alpha-pinene and limonene enantiomers
in the pine weevil, Hylobius abietis. J. Chem. Ecol. 24, 273–287.
Zhang, W., McAuslane, H.J., Schuster, D.J., 2004. Repellency of ginger oil to Bemisia
argentifolii (Homoptera:Aleyrodidae) on tomato. J. Econ. Entomol. 97, 1310–
1318.