Junji Takabayashi - Academia.edu (original) (raw)
Papers by Junji Takabayashi
Plant Signaling & Behavior, 2007
Applied Entomology and Zoology, 2006
Plant and Cell Physiology, 2009
Plant Physiology, 2004
Indirect defense of plants against herbivores often involves the induced emission of volatile inf... more Indirect defense of plants against herbivores often involves the induced emission of volatile infochemicals including terpenoids that attract natural enemies of the herbivores. We report the isolation and characterization of a terpene synthase cDNA (LjEβOS) from a model legume, Lotus japonicus. Recombinant LjEβOS enzyme produced (E)-β-ocimene (98%) and its Z-isomer (2%). Transcripts of LjEβOS were induced in L. japonicus plants infested with two-spotted spider mites (Tetranychus urticae), coinciding with increasing emissions of (E)-β-ocimene as well as other volatiles, (Z)-3-hexenyl acetate and (E)-4,8-dimethyl-1,3,7-nonatriene, by the infested plants. We suggest that LjEβOS is involved in the herbivore-induced indirect defense response of spider mite-infested L. japonicus via de novo formation and emission (E)-β-ocimene. Mechanical wounding of the leaves or application of alamethicin (ALA), a potent fungal elicitor of plant volatile emission, also induced transiently increased leve...
Phytochemistry, 2008
C6-aldehydes, such as (Z)-3-hexenal, (E)-2-hexenal, and n-hexanal, are volatile compounds formed ... more C6-aldehydes, such as (Z)-3-hexenal, (E)-2-hexenal, and n-hexanal, are volatile compounds formed by hydroperoxide lyase (HPL) and found in most terrestrial plants. They are fungicidal and bactericidal compounds, and are also signaling compounds to induce defense responses in plants. Transgenic plants having overexpressed or suppressed HPL activity (SH or ASH, respectively) showed lower or higher susceptibility against a necrotrophic fungal pathogen, Botrytis cinerea. In this study, we examined whether the modulated susceptibility was accountable to the direct fungicidal activity or to the signaling potency of C6-aldehydes. When wild-type Arabidopsis leaves were inoculated with B. cinerea, HPL expression was upregulated, and concomitantly, the amounts of C6-aldehydes increased. Higher amounts of C6-aldehydes found in inoculated SH plants inhibited growth of B. cinerea in vitro, while lower amounts found in ASH plants caused no inhibitory effect on the fungi. Thus, it was suggested that direct fungicidal activity of C6-aldehydes accounted for the modulated susceptibility. With SH plants higher amounts of camalexin could be found, but with the ASH plants no difference from wild-type plants could be found. Surplus amounts of C6-aldehydes could induce formation of camalexin as signaling compounds; however, this was not the case with wild-type and ASH plants. Accordingly, it could be assumed that direct fungicidal activity of C6-aldehydes were prominently responsible to the defense against B. cinerea but their signaling roles could be little responsible if any.
Phytochemistry, 1991
Abstract Headspace analyses of uninfested Lima bean ( Phaseolus lunatus ) leaves show an absence ... more Abstract Headspace analyses of uninfested Lima bean ( Phaseolus lunatus ) leaves show an absence of or only trace amounts of the terpenoids ( E )-β-ocimene and ( E )-4,8-dimethyl-1,3,7-nonatriene. Upon infestation by two-spotted spider-mites ( Tetranychus urticae ), Lima bean leaves produce ( E )-β-ocimene and ( E )-4,8-dimethyl-1,3,7-nonatriene which attract predators of the herbivore, a phenomenon known as indirect defence. When uninfested Lima bean leaves were placed on wet cotton wool upon which leaves that were partially infested with spider-mites, were also placed, the uninfested leaf tissue emitted the terpenoids in relatively high amounts: ca 20–40% of the amounts emitted by the infested leaf tissue. The same effect was found when uninfested leaves were put on wet cotton wool on which infested leaves had previously lain. The data show that an elicitor(s) from spider-mite infested leaves induces the production of ( E )-β-ocimene and ( E )-4,8-dimethyl-1,3,7-nonatriene in uninfested Lima bean leaves. This is the first chemical evidence for induction of indirect defence in uninfested leaves.
Phytochemistry, 2006
Since volatile allo-ocimene enhances resistance of Arabidopsis thaliana against Botrytis cinerea,... more Since volatile allo-ocimene enhances resistance of Arabidopsis thaliana against Botrytis cinerea, we attempted to dissect the factors involved in this induced resistance. The penetration of B. cinerea hyphae into Arabidopsis epidermis and the growth of hyphae after penetration were suppressed on allo-ocimene-treated leaves. allo-Ocimene also induced lignification on cell walls and veins of the leaves. The treatment induced accumulation of antifungal substances including the Arabidopsis phytoalexin, camalexin. Induction of lignification and accumulation of camalexin elicited by B. cinerea infection on Arabidopsis leaves after treating with allo-ocimene was faster and more intense than that observed with the leaves that had not been treated with this volatile. This suggested that allo-ocimene could prime defensive responses in Arabidopsis. allo-Ocimene enhanced resistant against B. cinerea in an ethylene resistant mutant (etr1-1), a jasmonic acid resistant mutant (jar1-1) and a salicylic acid resistant mutant (npr1-1). Thus, it is suggested that a signaling pathway independent for ETR1, JAR1 and NPR1 was operative to induce the resistance. The series of responses observed after allo-ocimene-treatment was mostly similar to that observed after C6-aldehyde-treatment. The effect of C6-aldehyde-treatment has been largely accounted to the chemical reactivities of the compounds; however, from this result it can be suggested that resistance responses of Arabidopsis could be induced by the volatiles mostly independent on their reactivities and that a common signaling pathway unaffected by the reactivities of compound was activated by the volatiles.
New Phytologist, 2012
• Plants under herbivore attack emit mixtures of volatiles (herbivore-induced plant volatiles, HI... more • Plants under herbivore attack emit mixtures of volatiles (herbivore-induced plant volatiles, HIPVs) that can attract predators of the herbivores. Although the composition of HIPVs should be critical for the attraction, most studies of transgenic plant-emitted volatiles have simply addressed the effect of trans-volatiles without embedding in other endogenous plant volatiles. • We investigated the abilities of transgenic wishbone flower plants (Torenia hybrida and Torenia fournieri) infested with spider mites, emitting a trans-volatile ((E)-b-ocimene) in the presence or absence of endogenous volatiles (natural HIPVs and ⁄ or floral volatiles), to attract predatory mites (Phytoseiulus persimilis). • In both olfactory-and glasshouse-based assays, P. persimilis females were attracted to natural HIPVs from infested wildtype (wt) plants of T. hybrida but not to those of T. fournieri. The trans-volatile enhanced the ability to attract P. persimilis only when added to an active HIPV blend from the infested transgenic T. hybrida plants, in comparison with the attraction by infested wt plants. Intriguingly, floral volatiles abolished the enhanced attractive ability of T. hybrida transformants, although floral volatiles themselves did not elicit any attraction or avoidance behavior. • Predator responses to trans-volatiles were found to depend on various background volatiles (e.g. natural HIPVs and floral volatiles) endogenously emitted by the transgenic plants.
Journal of Chemical Ecology, 2006
In response to herbivory by spider mites (Tetranychus urticae), lima bean plants produced signifi... more In response to herbivory by spider mites (Tetranychus urticae), lima bean plants produced significantly greater quantities of extrafloral nectar (EFN) than intact conspecific plants. Moreover, EFN amounts of infested plants depended on exposure to odor of infested neighbor plants. Two d after spider mite infestation, a test plant produced more EFN when exposed prior to infestation to volatiles from infested neighbor plants than when exposed to volatiles from uninfested conspecific plants. However, this effect was only detectable 2 d after spider mite infestation and vanished 4 d after infestation. These results suggest that EFN production is enhanced during the earlier stages of damage by T. urticae in response to previous exposure to volatiles from infested neighbor plants.
Journal of Chemical Ecology, 2010
Females of the solitary endoparasitoid Cotesia vestalis respond to a blend of volatile organic co... more Females of the solitary endoparasitoid Cotesia vestalis respond to a blend of volatile organic compounds (VOCs) released from plants infested with larvae of their host, the diamondback moth (Plutella xylostella), which is an important pest insect of cruciferous plants. We investigated the flight response of female parasitoids to the cruciferous plant Brassica rapa, using two-choice tests under laboratory conditions. The parasitoids were more attracted to plants that had been infested for at least 6 hr by the host larvae compared to intact plants, but they did not distinguish between plants infested for only 3 hr and intact plants. Although parasitoids preferred plants 1 and 2 days after herbivory (formerly infested plants) over intact plants they also preferred plants that had been infested for 24 hr over formerly infested plants. This suggests that parasitoids can distinguish between the VOC profiles of currently and formerly infested plants. We screened for differences in VOC emissions among the treatments and found that levels of benzyl cyanide and dimethyl trisulfide significantly decreased after removal of the host larvae, whereas terpenoids and their related compounds continued to be released at high levels. Benzyl cyanide and dimethyl trisulfide attracted parasitoids in a dose-dependent manner, whereas the other compounds were not attractive. These results suggest that nitrile and sulfide compounds temporarily released from plants under attack by host larvae are potentially more effective attractants for this parasitoid than other VOCs that are continuously released by hostdamaged plants.
Journal of Chemical Ecology, 1990
To understand the role of allelochemicals in predator-prey interactions it is not sufficient to s... more To understand the role of allelochemicals in predator-prey interactions it is not sufficient to study the behavioral responses of predator and prey, One should elucidate the origin of the allelochemicals and be aware that it may be located at another trophic level. These aspects are reviewed for predator-prey interactions in general and illustrated in detail for interactions between predatory mites and herbivorous mites. In the latter system there is behavioral and chemical evidence for the involvement of the host plant in production of volatile allelochemicals upon damage by the herbivores with the consequence of attracting predators. These volatiles not only influence predator behavior, but also prey behavior and even the attractiveness of nearby plants to predators. Herbivorous mites disperse away from places with high concentrations of the volatiles, and undamaged plants attract more predators when previously exposed to volatites from infested conspecific plants
Journal of Chemical Ecology, 1990
Aphytis yanonensis De Bach & Rosen, a parasitic wasp of the arrowhead scale,Unaspis yanon... more Aphytis yanonensis De Bach & Rosen, a parasitic wasp of the arrowhead scale,Unaspis yanonensis (Kuwana), was introduced to Japan to controlU. yanonensis. A. yanonensis recognizes a host insect by antennal contact and deposits eggs on the insect body underneath the scale. Ovipositional behavior is induced by perceiving the cuticular wax of the host insect,U. yanonensis, and other coccoids. Chemical composition of the cuticular wax was analyzed and oviposition stimulants were isolated following a bioassay usingA. yanonensis.
Journal of Chemical Ecology, 2006
To elucidate the role of the plant lipoxygenase (LOX)/lyase pathway for host search behavior of t... more To elucidate the role of the plant lipoxygenase (LOX)/lyase pathway for host search behavior of two parasitic wasps attacking herbivorous larvae, an Arabidopsis mutant (all84) was isolated with a mutation somewhere in the LOX/lyase pathway. Detached leaves of the mutant were shown to release less (Z)-3-hexenal, a first green leaf volatile (GLV) product of the LOX/lyase pathway. The braconid larval parasitoids studied, Cotesia glomerata and Cotesia plutella, differ in their ability to discriminate among plant volatiles induced by feeding of lepidopteran hosts and nonhosts: C. plutella only responds to plant volatiles induced by hosts (Plutella larvae), whereas the response by the more generalist C. glomerata is not host specific. The Arabidopsis mutant all84 infested by Pieris larvae was less attractive to C. glomerata than Arabidopsis wild type (wt) infested by the host larvae. C. glomerata was attracted by two of the GLV biosynthesized through the LOX/lyase pathway, (E)-2-hexenal and (Z)-3-hexenyl acetate. However, attraction of C. plutellae to volatiles from Plutella-infested all84 plants did not differ from attraction to host-infested wt Arabidopsis. Both wasp species were arrested to the respective host-infested edge of the wt leaf by showing characteristic antennal searching behavior on the edge. In C. glomerata, the duration of this searching behavior at the infested leaf edge was significantly shorter on all84 plants than on wt plants. By contrast, the duration of the searching behavior of C. plutellae on the host-infested leaf edge of all84 was not significantly different from that on the wt leaf. These data suggest that the LOX/lyase pathway is directly involved in the production of attractants and arrestants important for host search behavior of the more generalist C. glomerata, but not for the specialist C. plutellae.
Journal of Chemical Ecology, 2005
We investigated volatile infochemicals possibly involved in location of the generalist predatory ... more We investigated volatile infochemicals possibly involved in location of the generalist predatory mite Neoseiulus californicus to plants infested with spider mites in a Y-tube olfactometer. The predators significantly preferred volatiles from lima bean leaves infested with Tetranychus urticae to uninfested lima bean leaves. Likewise, they were attracted to volatiles from artificially damaged lima bean leaves and those from T. urticae plus their visible products. Significantly more predators chose infested lima bean leaves from which T. urticae plus their visible products had been removed than artificially damaged leaves, T. urticae, and their visible products. These results suggest that N. californicus is capable of exploiting a variety of volatile infochemicals originating from their prey, from the prey-foodplants themselves, and from the complex of the prey and the host plants (e.g., herbivore-induced volatiles). We also investigated predator response to some of the synthetic samples identified as volatile components emitted from T. urticae-infested lima bean leaves and/or artificially damaged lima bean leaves. The predators were attracted to each of the five synthetic volatile components: linalool, methyl salicylate, (Z)-3-hexen-1-ol, (E)-2-hexenal, and (Z)-3-hexenyl acetate. The role of each volatile compound in prey-searching behavior is discussed.
Journal of Chemical Ecology, 2011
Females of the gregarious endoparasitoid Cotesia kariyai were attracted to a blend of volatiles r... more Females of the gregarious endoparasitoid Cotesia kariyai were attracted to a blend of volatiles released from corn plants infested with larvae of their host, the common armyworm (Mythimna separata). We investigated the effects of time after the last infestation (1-168 h) on the attractiveness of corn plants infested by host larvae by using a wind tunnel under laboratory conditions. Immediately after the removal of the larvae, parasitoids were attracted more to plants that had been infested with the larvae than to intact plants (control). This attractiveness gradually decreased with time after the last infestation. The attractiveness of the infested plants was significantly higher than that of intact plants when the time after the last infestation was within 1 day. Fifteen herbivore-induced volatiles were recorded in the headspace of infested corn plants irrespective of time. The amounts of some compounds including (Z)-3-hexen-1-yl acetate, which have already been reported to attract C. kariyai, correlated with the attractiveness. The ecological meaning of the duration of production of C. kariyai attractants is discussed.
Journal of Chemical Ecology, 2008
Responses of the tachinid fly Exorista japonica Townsend to odors from corn plants infested with ... more Responses of the tachinid fly Exorista japonica Townsend to odors from corn plants infested with the fly's host, the larvae of the noctuid moth Mythimna separata (Walker), were examined in a wind tunnel. Naïve female flies showed a higher rate of landing on M. separata-infested corn plants from which the host larvae had been removed than on artificially damaged or intact corn plants. When paper impregnated with a solution of headspace volatiles collected from host-infested plants was attached to intact plants, females landed on the plants at a high rate. Females also responded to intact plants to which had been attached with paper impregnated with a synthetic blend of nine chemicals identified previously in host-infested plants. There was an optimum concentration of the synthetic blend for the females' landing. Of the nine chemicals identified previously, four [(E)-4,8-dimethyl-1,3,7-nonatriene, indole, 3-hydroxy-2-butanone, and 2-methyl-1-propanol] released only by host-infested plants were classified as a host-induced blend. The other five [(Z)-3-hexen-1-yl acetate, (E)-2-hexenal, hexanal, (Z)-3-hexen-1-ol, and linalool] were classified as a non-specific blend released not only by infested plants but also by artificially damaged or intact plants. In the wind tunnel, E. japonica females did not respond to intact plants to which paper containing a solution of non-specific blend or host-induced blend was attached. However, they showed a high level of response to a mixture of the non-specific and host-induced blends. These results indicate that naïve E. japonica use a combination of non-specific and host-induced blends as an olfactory cue for locating host-infested plants.
Journal of Chemical Ecology, 2010
When predators invade a leaf patch inhabited by herbivores, the herbivores disperse to a neighbor... more When predators invade a leaf patch inhabited by herbivores, the herbivores disperse to a neighboring predator-free leaf patch, thus escaping from the predators. However, the neighboring patch might already be used by con-or heterospecific herbivores. We used laboratory bioassays to examine whether perception of odor from con-or heterospecific competitors on a neighbored lima bean leaf patch influences dispersal behavior of the herbivorous mite Tetranychus urticae when attacked by predatory mites Phytoseiulus persimilis. The dispersal rates of T. urticae that perceived odors from leaf patches infested by conspecifics or cowpea aphids (Aphis craccivora) did not differ from the control (the dispersal rate of T. urticae that perceived odor from uninfested leaf patches). By contrast, the dispersal rate of T. urticae was reduced when they perceived odors from leaf patches that were currently or had previously been infested by larvae of the common cutworm (Spodoptera litura). Previous herbivory by S. litura larvae induced resistance in leaf patches to T. urticae as indicated by the reduced number of eggs laid by T. urticae. Our results are discussed with respect to the feeding behavior of the tested competitors of T. urticae and the impact of the plant and arthropod community on the dispersal behavior of these mites.
Journal of Chemical Ecology, 2010
Young, gregariously living larvae of the willow leaf beetles Plagiodera versicolora are known to ... more Young, gregariously living larvae of the willow leaf beetles Plagiodera versicolora are known to exhibit characteristic aggregation-dispersion-reaggregation behavior and local fidelity to a host tree. In this study, we investigated whether plant volatiles induced by feeding P. versicolora larvae were involved in the reaggregation behavior. Under laboratory conditions, we conducted dual-choice bioassays and found that the first and second instars discriminated between volatiles from leaves infested by larvae and volatiles from uninfested leaves. The discriminative behavior was dependent on both the time leaves were infested and the age of discriminating larvae. First and second instars preferred odor from 1-d-infested leaves to odor from uninfested leaves, whereas third instars (solitary stage) did not discriminate between these volatile blends. Odor from 2-d-infested leaves was preferred to odor from 1-d-infested leaves by first instars, whereas odor from leaves infested for 3 d was not attractive to these very young larvae. Neither was odor of leaves infested for 1 d and then left uninfested for 1 or 2 d attractive to young larvae. The data suggest that the first and second instars use volatiles from a leaf newly infested by conspecific larvae as one of the reaggregation cues. We detected several herbivore-induced compounds in the headspace of the attractive leaves. Among those, a mixture of synthetic (E)-beta-ocimene, (Z)-beta-ocimene, allo-ocimene, and linalool was found to attract the larvae.
Journal of Chemical Ecology, 1995
Journal of Chemical Ecology, 1994
Plants may defend themselves against herbivores by enhancing the effectiveness of natural enemies... more Plants may defend themselves against herbivores by enhancing the effectiveness of natural enemies of herbivores. This is termed "indirect defense," which may be induced by herbivore damage. An important aspect of induced indirect defense is the attraction of the herbivore's natural enemies to infested plants by the plant emitting so-called "herbivore-induced synomone" (HIS) in response to herbivore damage. In this paper, we review the role of terpenoids in the induced indirect defense of plants against herbivorous mites. HIS are emitted from both damaged and undamaged areas of infested plants, and the composition of HIS varies among different plant species. The emission of HIS may also vary within a plant species, depending upon: (1) plant cultivar, (2) leaf growth stage, (3) the herbivore species that is attacking, and (4) abiotic conditions (light intensity, time of year, and water stress). Predatory mites cope with this variation of HIS by innate recognition as well as temporary specialization to a certain HIS via learning.
Plant Signaling & Behavior, 2007
Applied Entomology and Zoology, 2006
Plant and Cell Physiology, 2009
Plant Physiology, 2004
Indirect defense of plants against herbivores often involves the induced emission of volatile inf... more Indirect defense of plants against herbivores often involves the induced emission of volatile infochemicals including terpenoids that attract natural enemies of the herbivores. We report the isolation and characterization of a terpene synthase cDNA (LjEβOS) from a model legume, Lotus japonicus. Recombinant LjEβOS enzyme produced (E)-β-ocimene (98%) and its Z-isomer (2%). Transcripts of LjEβOS were induced in L. japonicus plants infested with two-spotted spider mites (Tetranychus urticae), coinciding with increasing emissions of (E)-β-ocimene as well as other volatiles, (Z)-3-hexenyl acetate and (E)-4,8-dimethyl-1,3,7-nonatriene, by the infested plants. We suggest that LjEβOS is involved in the herbivore-induced indirect defense response of spider mite-infested L. japonicus via de novo formation and emission (E)-β-ocimene. Mechanical wounding of the leaves or application of alamethicin (ALA), a potent fungal elicitor of plant volatile emission, also induced transiently increased leve...
Phytochemistry, 2008
C6-aldehydes, such as (Z)-3-hexenal, (E)-2-hexenal, and n-hexanal, are volatile compounds formed ... more C6-aldehydes, such as (Z)-3-hexenal, (E)-2-hexenal, and n-hexanal, are volatile compounds formed by hydroperoxide lyase (HPL) and found in most terrestrial plants. They are fungicidal and bactericidal compounds, and are also signaling compounds to induce defense responses in plants. Transgenic plants having overexpressed or suppressed HPL activity (SH or ASH, respectively) showed lower or higher susceptibility against a necrotrophic fungal pathogen, Botrytis cinerea. In this study, we examined whether the modulated susceptibility was accountable to the direct fungicidal activity or to the signaling potency of C6-aldehydes. When wild-type Arabidopsis leaves were inoculated with B. cinerea, HPL expression was upregulated, and concomitantly, the amounts of C6-aldehydes increased. Higher amounts of C6-aldehydes found in inoculated SH plants inhibited growth of B. cinerea in vitro, while lower amounts found in ASH plants caused no inhibitory effect on the fungi. Thus, it was suggested that direct fungicidal activity of C6-aldehydes accounted for the modulated susceptibility. With SH plants higher amounts of camalexin could be found, but with the ASH plants no difference from wild-type plants could be found. Surplus amounts of C6-aldehydes could induce formation of camalexin as signaling compounds; however, this was not the case with wild-type and ASH plants. Accordingly, it could be assumed that direct fungicidal activity of C6-aldehydes were prominently responsible to the defense against B. cinerea but their signaling roles could be little responsible if any.
Phytochemistry, 1991
Abstract Headspace analyses of uninfested Lima bean ( Phaseolus lunatus ) leaves show an absence ... more Abstract Headspace analyses of uninfested Lima bean ( Phaseolus lunatus ) leaves show an absence of or only trace amounts of the terpenoids ( E )-β-ocimene and ( E )-4,8-dimethyl-1,3,7-nonatriene. Upon infestation by two-spotted spider-mites ( Tetranychus urticae ), Lima bean leaves produce ( E )-β-ocimene and ( E )-4,8-dimethyl-1,3,7-nonatriene which attract predators of the herbivore, a phenomenon known as indirect defence. When uninfested Lima bean leaves were placed on wet cotton wool upon which leaves that were partially infested with spider-mites, were also placed, the uninfested leaf tissue emitted the terpenoids in relatively high amounts: ca 20–40% of the amounts emitted by the infested leaf tissue. The same effect was found when uninfested leaves were put on wet cotton wool on which infested leaves had previously lain. The data show that an elicitor(s) from spider-mite infested leaves induces the production of ( E )-β-ocimene and ( E )-4,8-dimethyl-1,3,7-nonatriene in uninfested Lima bean leaves. This is the first chemical evidence for induction of indirect defence in uninfested leaves.
Phytochemistry, 2006
Since volatile allo-ocimene enhances resistance of Arabidopsis thaliana against Botrytis cinerea,... more Since volatile allo-ocimene enhances resistance of Arabidopsis thaliana against Botrytis cinerea, we attempted to dissect the factors involved in this induced resistance. The penetration of B. cinerea hyphae into Arabidopsis epidermis and the growth of hyphae after penetration were suppressed on allo-ocimene-treated leaves. allo-Ocimene also induced lignification on cell walls and veins of the leaves. The treatment induced accumulation of antifungal substances including the Arabidopsis phytoalexin, camalexin. Induction of lignification and accumulation of camalexin elicited by B. cinerea infection on Arabidopsis leaves after treating with allo-ocimene was faster and more intense than that observed with the leaves that had not been treated with this volatile. This suggested that allo-ocimene could prime defensive responses in Arabidopsis. allo-Ocimene enhanced resistant against B. cinerea in an ethylene resistant mutant (etr1-1), a jasmonic acid resistant mutant (jar1-1) and a salicylic acid resistant mutant (npr1-1). Thus, it is suggested that a signaling pathway independent for ETR1, JAR1 and NPR1 was operative to induce the resistance. The series of responses observed after allo-ocimene-treatment was mostly similar to that observed after C6-aldehyde-treatment. The effect of C6-aldehyde-treatment has been largely accounted to the chemical reactivities of the compounds; however, from this result it can be suggested that resistance responses of Arabidopsis could be induced by the volatiles mostly independent on their reactivities and that a common signaling pathway unaffected by the reactivities of compound was activated by the volatiles.
New Phytologist, 2012
• Plants under herbivore attack emit mixtures of volatiles (herbivore-induced plant volatiles, HI... more • Plants under herbivore attack emit mixtures of volatiles (herbivore-induced plant volatiles, HIPVs) that can attract predators of the herbivores. Although the composition of HIPVs should be critical for the attraction, most studies of transgenic plant-emitted volatiles have simply addressed the effect of trans-volatiles without embedding in other endogenous plant volatiles. • We investigated the abilities of transgenic wishbone flower plants (Torenia hybrida and Torenia fournieri) infested with spider mites, emitting a trans-volatile ((E)-b-ocimene) in the presence or absence of endogenous volatiles (natural HIPVs and ⁄ or floral volatiles), to attract predatory mites (Phytoseiulus persimilis). • In both olfactory-and glasshouse-based assays, P. persimilis females were attracted to natural HIPVs from infested wildtype (wt) plants of T. hybrida but not to those of T. fournieri. The trans-volatile enhanced the ability to attract P. persimilis only when added to an active HIPV blend from the infested transgenic T. hybrida plants, in comparison with the attraction by infested wt plants. Intriguingly, floral volatiles abolished the enhanced attractive ability of T. hybrida transformants, although floral volatiles themselves did not elicit any attraction or avoidance behavior. • Predator responses to trans-volatiles were found to depend on various background volatiles (e.g. natural HIPVs and floral volatiles) endogenously emitted by the transgenic plants.
Journal of Chemical Ecology, 2006
In response to herbivory by spider mites (Tetranychus urticae), lima bean plants produced signifi... more In response to herbivory by spider mites (Tetranychus urticae), lima bean plants produced significantly greater quantities of extrafloral nectar (EFN) than intact conspecific plants. Moreover, EFN amounts of infested plants depended on exposure to odor of infested neighbor plants. Two d after spider mite infestation, a test plant produced more EFN when exposed prior to infestation to volatiles from infested neighbor plants than when exposed to volatiles from uninfested conspecific plants. However, this effect was only detectable 2 d after spider mite infestation and vanished 4 d after infestation. These results suggest that EFN production is enhanced during the earlier stages of damage by T. urticae in response to previous exposure to volatiles from infested neighbor plants.
Journal of Chemical Ecology, 2010
Females of the solitary endoparasitoid Cotesia vestalis respond to a blend of volatile organic co... more Females of the solitary endoparasitoid Cotesia vestalis respond to a blend of volatile organic compounds (VOCs) released from plants infested with larvae of their host, the diamondback moth (Plutella xylostella), which is an important pest insect of cruciferous plants. We investigated the flight response of female parasitoids to the cruciferous plant Brassica rapa, using two-choice tests under laboratory conditions. The parasitoids were more attracted to plants that had been infested for at least 6 hr by the host larvae compared to intact plants, but they did not distinguish between plants infested for only 3 hr and intact plants. Although parasitoids preferred plants 1 and 2 days after herbivory (formerly infested plants) over intact plants they also preferred plants that had been infested for 24 hr over formerly infested plants. This suggests that parasitoids can distinguish between the VOC profiles of currently and formerly infested plants. We screened for differences in VOC emissions among the treatments and found that levels of benzyl cyanide and dimethyl trisulfide significantly decreased after removal of the host larvae, whereas terpenoids and their related compounds continued to be released at high levels. Benzyl cyanide and dimethyl trisulfide attracted parasitoids in a dose-dependent manner, whereas the other compounds were not attractive. These results suggest that nitrile and sulfide compounds temporarily released from plants under attack by host larvae are potentially more effective attractants for this parasitoid than other VOCs that are continuously released by hostdamaged plants.
Journal of Chemical Ecology, 1990
To understand the role of allelochemicals in predator-prey interactions it is not sufficient to s... more To understand the role of allelochemicals in predator-prey interactions it is not sufficient to study the behavioral responses of predator and prey, One should elucidate the origin of the allelochemicals and be aware that it may be located at another trophic level. These aspects are reviewed for predator-prey interactions in general and illustrated in detail for interactions between predatory mites and herbivorous mites. In the latter system there is behavioral and chemical evidence for the involvement of the host plant in production of volatile allelochemicals upon damage by the herbivores with the consequence of attracting predators. These volatiles not only influence predator behavior, but also prey behavior and even the attractiveness of nearby plants to predators. Herbivorous mites disperse away from places with high concentrations of the volatiles, and undamaged plants attract more predators when previously exposed to volatites from infested conspecific plants
Journal of Chemical Ecology, 1990
Aphytis yanonensis De Bach & Rosen, a parasitic wasp of the arrowhead scale,Unaspis yanon... more Aphytis yanonensis De Bach & Rosen, a parasitic wasp of the arrowhead scale,Unaspis yanonensis (Kuwana), was introduced to Japan to controlU. yanonensis. A. yanonensis recognizes a host insect by antennal contact and deposits eggs on the insect body underneath the scale. Ovipositional behavior is induced by perceiving the cuticular wax of the host insect,U. yanonensis, and other coccoids. Chemical composition of the cuticular wax was analyzed and oviposition stimulants were isolated following a bioassay usingA. yanonensis.
Journal of Chemical Ecology, 2006
To elucidate the role of the plant lipoxygenase (LOX)/lyase pathway for host search behavior of t... more To elucidate the role of the plant lipoxygenase (LOX)/lyase pathway for host search behavior of two parasitic wasps attacking herbivorous larvae, an Arabidopsis mutant (all84) was isolated with a mutation somewhere in the LOX/lyase pathway. Detached leaves of the mutant were shown to release less (Z)-3-hexenal, a first green leaf volatile (GLV) product of the LOX/lyase pathway. The braconid larval parasitoids studied, Cotesia glomerata and Cotesia plutella, differ in their ability to discriminate among plant volatiles induced by feeding of lepidopteran hosts and nonhosts: C. plutella only responds to plant volatiles induced by hosts (Plutella larvae), whereas the response by the more generalist C. glomerata is not host specific. The Arabidopsis mutant all84 infested by Pieris larvae was less attractive to C. glomerata than Arabidopsis wild type (wt) infested by the host larvae. C. glomerata was attracted by two of the GLV biosynthesized through the LOX/lyase pathway, (E)-2-hexenal and (Z)-3-hexenyl acetate. However, attraction of C. plutellae to volatiles from Plutella-infested all84 plants did not differ from attraction to host-infested wt Arabidopsis. Both wasp species were arrested to the respective host-infested edge of the wt leaf by showing characteristic antennal searching behavior on the edge. In C. glomerata, the duration of this searching behavior at the infested leaf edge was significantly shorter on all84 plants than on wt plants. By contrast, the duration of the searching behavior of C. plutellae on the host-infested leaf edge of all84 was not significantly different from that on the wt leaf. These data suggest that the LOX/lyase pathway is directly involved in the production of attractants and arrestants important for host search behavior of the more generalist C. glomerata, but not for the specialist C. plutellae.
Journal of Chemical Ecology, 2005
We investigated volatile infochemicals possibly involved in location of the generalist predatory ... more We investigated volatile infochemicals possibly involved in location of the generalist predatory mite Neoseiulus californicus to plants infested with spider mites in a Y-tube olfactometer. The predators significantly preferred volatiles from lima bean leaves infested with Tetranychus urticae to uninfested lima bean leaves. Likewise, they were attracted to volatiles from artificially damaged lima bean leaves and those from T. urticae plus their visible products. Significantly more predators chose infested lima bean leaves from which T. urticae plus their visible products had been removed than artificially damaged leaves, T. urticae, and their visible products. These results suggest that N. californicus is capable of exploiting a variety of volatile infochemicals originating from their prey, from the prey-foodplants themselves, and from the complex of the prey and the host plants (e.g., herbivore-induced volatiles). We also investigated predator response to some of the synthetic samples identified as volatile components emitted from T. urticae-infested lima bean leaves and/or artificially damaged lima bean leaves. The predators were attracted to each of the five synthetic volatile components: linalool, methyl salicylate, (Z)-3-hexen-1-ol, (E)-2-hexenal, and (Z)-3-hexenyl acetate. The role of each volatile compound in prey-searching behavior is discussed.
Journal of Chemical Ecology, 2011
Females of the gregarious endoparasitoid Cotesia kariyai were attracted to a blend of volatiles r... more Females of the gregarious endoparasitoid Cotesia kariyai were attracted to a blend of volatiles released from corn plants infested with larvae of their host, the common armyworm (Mythimna separata). We investigated the effects of time after the last infestation (1-168 h) on the attractiveness of corn plants infested by host larvae by using a wind tunnel under laboratory conditions. Immediately after the removal of the larvae, parasitoids were attracted more to plants that had been infested with the larvae than to intact plants (control). This attractiveness gradually decreased with time after the last infestation. The attractiveness of the infested plants was significantly higher than that of intact plants when the time after the last infestation was within 1 day. Fifteen herbivore-induced volatiles were recorded in the headspace of infested corn plants irrespective of time. The amounts of some compounds including (Z)-3-hexen-1-yl acetate, which have already been reported to attract C. kariyai, correlated with the attractiveness. The ecological meaning of the duration of production of C. kariyai attractants is discussed.
Journal of Chemical Ecology, 2008
Responses of the tachinid fly Exorista japonica Townsend to odors from corn plants infested with ... more Responses of the tachinid fly Exorista japonica Townsend to odors from corn plants infested with the fly's host, the larvae of the noctuid moth Mythimna separata (Walker), were examined in a wind tunnel. Naïve female flies showed a higher rate of landing on M. separata-infested corn plants from which the host larvae had been removed than on artificially damaged or intact corn plants. When paper impregnated with a solution of headspace volatiles collected from host-infested plants was attached to intact plants, females landed on the plants at a high rate. Females also responded to intact plants to which had been attached with paper impregnated with a synthetic blend of nine chemicals identified previously in host-infested plants. There was an optimum concentration of the synthetic blend for the females' landing. Of the nine chemicals identified previously, four [(E)-4,8-dimethyl-1,3,7-nonatriene, indole, 3-hydroxy-2-butanone, and 2-methyl-1-propanol] released only by host-infested plants were classified as a host-induced blend. The other five [(Z)-3-hexen-1-yl acetate, (E)-2-hexenal, hexanal, (Z)-3-hexen-1-ol, and linalool] were classified as a non-specific blend released not only by infested plants but also by artificially damaged or intact plants. In the wind tunnel, E. japonica females did not respond to intact plants to which paper containing a solution of non-specific blend or host-induced blend was attached. However, they showed a high level of response to a mixture of the non-specific and host-induced blends. These results indicate that naïve E. japonica use a combination of non-specific and host-induced blends as an olfactory cue for locating host-infested plants.
Journal of Chemical Ecology, 2010
When predators invade a leaf patch inhabited by herbivores, the herbivores disperse to a neighbor... more When predators invade a leaf patch inhabited by herbivores, the herbivores disperse to a neighboring predator-free leaf patch, thus escaping from the predators. However, the neighboring patch might already be used by con-or heterospecific herbivores. We used laboratory bioassays to examine whether perception of odor from con-or heterospecific competitors on a neighbored lima bean leaf patch influences dispersal behavior of the herbivorous mite Tetranychus urticae when attacked by predatory mites Phytoseiulus persimilis. The dispersal rates of T. urticae that perceived odors from leaf patches infested by conspecifics or cowpea aphids (Aphis craccivora) did not differ from the control (the dispersal rate of T. urticae that perceived odor from uninfested leaf patches). By contrast, the dispersal rate of T. urticae was reduced when they perceived odors from leaf patches that were currently or had previously been infested by larvae of the common cutworm (Spodoptera litura). Previous herbivory by S. litura larvae induced resistance in leaf patches to T. urticae as indicated by the reduced number of eggs laid by T. urticae. Our results are discussed with respect to the feeding behavior of the tested competitors of T. urticae and the impact of the plant and arthropod community on the dispersal behavior of these mites.
Journal of Chemical Ecology, 2010
Young, gregariously living larvae of the willow leaf beetles Plagiodera versicolora are known to ... more Young, gregariously living larvae of the willow leaf beetles Plagiodera versicolora are known to exhibit characteristic aggregation-dispersion-reaggregation behavior and local fidelity to a host tree. In this study, we investigated whether plant volatiles induced by feeding P. versicolora larvae were involved in the reaggregation behavior. Under laboratory conditions, we conducted dual-choice bioassays and found that the first and second instars discriminated between volatiles from leaves infested by larvae and volatiles from uninfested leaves. The discriminative behavior was dependent on both the time leaves were infested and the age of discriminating larvae. First and second instars preferred odor from 1-d-infested leaves to odor from uninfested leaves, whereas third instars (solitary stage) did not discriminate between these volatile blends. Odor from 2-d-infested leaves was preferred to odor from 1-d-infested leaves by first instars, whereas odor from leaves infested for 3 d was not attractive to these very young larvae. Neither was odor of leaves infested for 1 d and then left uninfested for 1 or 2 d attractive to young larvae. The data suggest that the first and second instars use volatiles from a leaf newly infested by conspecific larvae as one of the reaggregation cues. We detected several herbivore-induced compounds in the headspace of the attractive leaves. Among those, a mixture of synthetic (E)-beta-ocimene, (Z)-beta-ocimene, allo-ocimene, and linalool was found to attract the larvae.
Journal of Chemical Ecology, 1995
Journal of Chemical Ecology, 1994
Plants may defend themselves against herbivores by enhancing the effectiveness of natural enemies... more Plants may defend themselves against herbivores by enhancing the effectiveness of natural enemies of herbivores. This is termed "indirect defense," which may be induced by herbivore damage. An important aspect of induced indirect defense is the attraction of the herbivore's natural enemies to infested plants by the plant emitting so-called "herbivore-induced synomone" (HIS) in response to herbivore damage. In this paper, we review the role of terpenoids in the induced indirect defense of plants against herbivorous mites. HIS are emitted from both damaged and undamaged areas of infested plants, and the composition of HIS varies among different plant species. The emission of HIS may also vary within a plant species, depending upon: (1) plant cultivar, (2) leaf growth stage, (3) the herbivore species that is attacking, and (4) abiotic conditions (light intensity, time of year, and water stress). Predatory mites cope with this variation of HIS by innate recognition as well as temporary specialization to a certain HIS via learning.