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1.
Gols R Bukovinszky T van Dam NM Dicke M Bullock JM Harvey JA 《Journal of chemical ecology》2008,34(2):132-143
Through artificial selection, domesticated plants often contain modified levels of primary and secondary metabolites compared
to their wild progenitors. It is hypothesized that the changed chemistry of cultivated plants will affect the performance
of insects associated with these plants. In this paper, the development of several specialist and generalist herbivores and
their endoparasitoids were compared when reared on a wild and cultivated population of cabbage, Brassica oleracea, and a recently established feral Brassica species. Irrespective of insect species or the degree of dietary specialization, herbivores and parasitoids developed most
poorly on the wild population. For the specialists, plant population influenced only development time and adult body mass,
whereas for the generalists, plant populations also affected egg-to-adult survival. Two parasitoid species, a generalist (Diadegma fenestrale) and a specialist (D. semiclausum), were reared from the same host (Plutella xylostella). Performance of D. semiclausum was closely linked to that of its host, whereas the correlation between survival of D. fenestrale and host performance was less clear. Plants in the Brassicaceae characteristically produce defense-related glucosinolates
(GS). Levels of GS in leaves of undamaged plants were significantly higher in plants from the wild population than from the
domesticated populations. Moreover, total GS concentrations increased significantly in wild plants after herbivory, but not
in domesticated or feral plants. The results of this study reveal that a cabbage cultivar and plants from a wild cabbage population
exhibit significant differences in quality in terms of their effects on the growth and development of insect herbivores and
their natural enemies. Although cultivated plants have proved to be model systems in agroecology, we argue that some caution
should be applied to evolutionary explanations derived from studies on domesticated plants, unless some knowledge exists on
the history of the system under investigation. 相似文献
2.
Smallegange RC van Loon JJ Blatt SE Harvey JA Agerbirk N Dicke M 《Journal of chemical ecology》2007,33(10):1831-1844
Interactions between butterflies and caterpillars in the genus Pieris and plants in the family Brassicaceae are among the best explored in the field of insect–plant biology. However, we report
here for the first time that Pieris brassicae, commonly assumed to be a typical folivore, actually prefers to feed on flowers of three Brassica nigra genotypes rather than on their leaves. First- and second-instar caterpillars were observed to feed primarily on leaves, whereas
late second and early third instars migrated via the small leaves of the flower branches to the flower buds and flowers. Once
flower feeding began, no further leaf feeding was observed. We investigated growth rates of caterpillars having access exclusively
to either leaves of flowering plants or flowers. In addition, we analyzed glucosinolate concentrations in leaves and flowers.
Late-second- and early-third-instar P. brassicae caterpillars moved upward into the inflorescences of B. nigra and fed on buds and flowers until the end of the final (fifth) instar, after which they entered into the wandering stage,
leaving the plant in search of a pupation site. Flower feeding sustained a significantly higher growth rate than leaf feeding.
Flowers contained levels of glucosinolates up to five times higher than those of leaves. Five glucosinolates were identified:
the aliphatic sinigrin, the aromatic phenyethylglucosinolate, and three indole glucosinolates: glucobrassicin, 4-methoxyglucobrassicin,
and 4-hydroxyglucobrassicin. Tissue type and genotype were the most important factors affecting levels of identified glucosinolates.
Sinigrin was by far the most abundant compound in all three genotypes. Sinigrin, 4-hydroxyglucobrassicin, and phenylethylglucosinolate
were present at significantly higher levels in flowers than in leaves. In response to caterpillar feeding, sinigrin levels
in both leaves and flowers were significantly higher than in undamaged plants, whereas 4-hydroxyglucobrassicin leaf levels
were lower. Our results show that feeding on flower tissues, containing higher concentrations of glucosinolates, provides
P. brassicae with a nutritional benefit in terms of higher growth rate. This preference appears to be in contrast to published negative
effects of volatile glucosinolate breakdown products on the closely related Pieris rapae. 相似文献
3.
Cyanide production has been reported from over 2500 plant species, including some members of the Brassicaceae. We report that
the important invasive plant, Alliaria petiolata, produces levels of cyanide in its tissues that can reach 100 ppm fresh weight (FW), a level considered toxic to many vertebrates.
In a comparative study, levels of cyanide in leaves of young first-year plants were 25 times higher than in leaves of young
Arabidopsis thaliana plants and over 150 times higher than in leaves of young Brassica kaber, B. rapa, and B. napus. In first-year plants, cyanide levels were highest in young leaves of seedlings and declined with leaf age on individual
plants. Leaves of young plants infested with green peach aphids (Myzus persicae) produced just over half as much cyanide as leaves of healthy plants, suggesting that aphid feeding led to loss of cyanide
from intact tissues before analysis, or that aphid feeding inhibited cyanide precursor production. In a developmental study,
levels of cyanide in the youngest and oldest leaf of young garlic mustard plants were four times lower than in the youngest
and oldest leaf of young Sorghum sudanense (cv. Cadan 97) plants, but cyanide levels did not decline in these leaves with plant age as in S. sudanense. Different populations of garlic mustard varied moderately in the constitutive and inducible expression of cyanide in leaves,
but no populations studied were acyanogenic. Although cyanide production could result from breakdown products of glucosinolates,
no cyanide was detected in vitro from decomposition of sinigrin, the major glucosinolate of garlic mustard. These studies indicate that cyanide produced from
an as yet unidentified cyanogenic compound is a part of the battery of chemical defenses expressed by garlic mustard. 相似文献
4.
The effects of limonene, a mixture of limonene + carvone (1:1, v/v), and methyl jasmonate (MeJA) on diamondback moth (DBM) (Plutella xylostella L.) oviposition, larval feeding, and the behavior of its larval parasitoid Cotesia plutellae (Kurdjumov) with cabbage (Brassica oleracea L. ssp. capitata, cvs. Rinda and Lennox) and broccoli (B. oleracea subsp. Italica cv Lucky) were tested. Limonene showed no deterrent effect on DBM when plants were sprayed with or exposed to limonene, although there was a cultivar difference. A mixture of limonene and carvone released from vermiculite showed a significant repellent effect, reducing the number of eggs laid on the cabbages. MeJA treatment reduced the relative growth rate (RGR) of larvae on cv Lennox leaves. In Y-tube olfactometer tests, C. plutellae preferred the odors of limonene and MeJA to filtered air. In cv Lennox, the parasitoid preferred DBM-damaged plants with limonene to such plants without limonene. C. plutellae females were repelled by the mixture of limonene + carvone. In both cultivars, exogenous MeJA induced the emission of the sesquiterpene (E,E)-α-farnesene, the homoterpene (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), and green leaf volatile (Z)-3-hexenyl acetate + octanal. The attractive effect of limonene and MeJA predicts that these two compounds can be used in sustainable plant protection strategies in organic farming. 相似文献
5.
Diaeretiella rapae, a parasitoid that predominately specializes in the parasitism of Brassica-feeding aphids, attacks Lipaphis erysimi, a specialist feeding aphid of the Brassicaceae and other families in the Capparales, at a greater rate than the generalist-feeding
aphid, Myzus persicae. In this study, we investigated the orientation behavior of D. rapae to the volatile chemicals produced when these two aphid species feed on turnip (Brassica rapa var rapifera). We showed no significant preference orientation behavior to either aphid/turnip complex over the other. Isothiocyanates
are among the compounds emitted by plants of the Brassicaceae in response to insect feeding damage, including by aphids. We
assessed parasitoid orientation behavior in response to laboratory-formulated isothiocyanates. We tested two formulations
and discovered significant orientation toward 3-butenyl isothiocyanate. We also assessed plant and aphid glucosinolate content,
and showed large levels of glucosinolate concentration in L. erysimi, whereas there was little change in plant content in response to aphid feeding. Our results suggest that during the process
of host location, similar cues may be utilized for locating L. erysimi and M. persicae, whereas the acceptance of hosts and their suitability may involve aspects of nonvolatile aphid chemistry. 相似文献
6.
Anagrus nilaparvatae, an egg parasitoid of the rice brown planthopper Nilaparvata lugens, was attracted to volatiles released from N. lugens-infested plants, whereas there was no attraction to volatiles from undamaged plants, artificially damaged plants, or volatiles
from N. lugens nymphs, female adults, eggs, honeydew, and exuvia. There was no difference in attractiveness between plants infested by N. lugens nymphs or those infested by gravid females. Attraction was correlated with time after infestation and host density; attraction
was only evident between 6 and 24 hr after infestation by 10 adult females per plant, but not before or after. Similarly,
after 24 hr of infestation, wasps were attracted to plants with 10 to 20 female planthoppers, but not to plants with lower
or higher numbers of female planthoppers. The attractive time periods and densities may be correlated with the survival chances
of the wasps' offspring, which do not survive if the plants die before the wasps emerge. Wasps were also attracted to undamaged
mature leaves of a rice plant when one of the other mature leaves had been infested by 10 N. lugens for 1 d, implying that the volatile cues involved in host location by the parasitoid are systemically released. Collection
and analyses of volatiles revealed that 1 d of N. lugens infestation did not result in the emission of new compounds or an increase in the total amount of volatiles, but rather the
proportions among the compounds in the blend were altered. The total amounts and proportions of the chemicals were also affected
by infestation duration. These changes in volatile profiles might provide the wasps with specific information on host habitat
quality and thus could explain the observed behavioral responses of the parasitoid. 相似文献
7.
Desert locusts (Schistocerca gregaria) occasionally feed on Schouwia purpurea, a plant that contains tenfold higher levels of glucosinolates than most other Brassicaceae. Whereas this unusually high
level of glucosinolates is expected to be toxic and/or deterrent to most insects, locusts feed on the plant with no apparent
ill effects. In this paper, we demonstrate that the desert locust, like larvae of the diamondback moth (Plutella xylostella), possesses a glucosinolate sulfatase in the gut that hydrolyzes glucosinolates to their corresponding desulfonated forms.
These are no longer susceptible to cleavage by myrosinase, thus eliminating the formation of toxic glucosinolate hydrolysis
products. Sulfatase is found throughout the desert locust gut and can catalyze the hydrolysis of all of the glucosinolates
present in S. purpurea. The enzyme was detected in all larval stages of locusts as well as in both male and female adults feeding on this plant
species. Glucosinolate sulfatase activity is induced tenfold when locusts are fed S. purpurea after being maintained on a glucosinolate-free diet, and activity declines when glucosinolates are removed from the locust
diet. A detoxification system that is sensitive to the dietary levels of a plant toxin may minimize the physiological costs
of toxin processing, especially for a generalist insect herbivore that encounters large variations in plant defense metabolites
while feeding on different species. 相似文献
8.
Herbivores walking over the epicuticular wax layer of a plant may leave tracks that disclose their presence to hunting predators
or parasitoids. The braconid wasp Cotesia marginiventris is a solitary parasitoid of young noctuid caterpillars. It can locate potential hosts from a distance by orienting toward
the scent of herbivore-damaged plants. Upon landing on the caterpillars’ food plant, the female parasitoid searches for further
cues (kairomones) that confirm the presence of a suitable host. In a previous study, we showed that C. marginiventris recognizes the chemical footprints of absent Spodoptera frugiperda caterpillars on a leaf. Here, we report on the persistence and chemical nature of this host location kairomone. In a series
of behavioral assays, we confirmed that caterpillars of S. frugiperda leave chemical tracks that elicit characteristic antennation behavior in C. marginiventris for up to 2 days. Both hexane extracts of caterpillar footprints and of the larvae’s ventral cuticle induced antennation
and contained almost identical long-chain hydrocarbons, thus suggesting the prolegs and claspers as the kairomones’ main source.
A series of linear C21 to C32 alkanes accounted for ca 90% of all identified compounds. Female wasps showed significant antennation responses on leaves
treated with a reconstructed blend of these n-alkanes. However, wasp responses were relatively weak. Therefore, we presume that minor compounds, such as monomethyl-branched
alkanes, which were also found, may contribute additionally to host recognition. 相似文献
9.
Caroline Müller Monique Schulz Eleonora Pagnotta Luisa Ugolini Ting Yang Annemarie Matthes Luca Lazzeri Niels Agerbirk 《Journal of chemical ecology》2018,44(12):1190-1205
We investigated the influences of two structurally similar glucosinolates, phenethylglucosinolate (gluconasturtiin, NAS) and its (S)-2-hydroxyl derivative glucobarbarin (BAR), as well as their hydrolysis products on larvae of the generalist Mamestra brassicae (Lepidoptera: Noctuidae). Previous results suggested a higher defensive activity of BAR than NAS based on resistance toward M. brassicae larvae of natural plant genotypes of Barbarea vulgaris R. Br. (Brassicaceae) dominated by BAR. In the present study, the hypothesis of a higher defensive activity of BAR than NAS was tested by comparing two Barbarea species similarly dominated either by BAR or by NAS and by testing effects of isolated BAR and NAS on larval survival and feeding preferences. Larvae reared on leaf disks of B. verna (Mill.) Asch. had a lower survival than those reared on B. vulgaris P- and G-chemotypes. Leaves of B. verna were dominated by NAS, whereas B. vulgaris chemotypes were dominated by BAR or its epimer. In addition, B. verna leaves showed a threefold higher activity of the glucosinolate-activating myrosinase enzymes. The main product of NAS from breakdown by endogenous enzymes including myrosinases (“autolysis”) in B. verna leaves was phenethyl isothiocyanate, while the main products of BAR in autolyzed B. vulgaris leaves were a cyclized isothiocyanate product, namely an oxazolidine-2-thione, and a downstream metabolite, an oxazolidin-2-one. The glucosinolates BAR and NAS were isolated and offered to larvae on disks of cabbage. Both glucosinolates exerted similar negative effects on larval survival but effects of NAS tended to be more detrimental. Low concentrations of BAR, but not of NAS, stimulated larval feeding, whereas high BAR concentrations acted deterrent. NAS only tended to be deterrent at the highest concentration, but the difference was not significant. Recoveries of NAS and BAR on cabbage leaf disks were similar, and when hydrolyzed by mechanical leaf damage, the same isothiocyanate-type products as in Barbarea plants were formed with further conversion of BAR to cyclic products, (R)-5-phenyloxazolidine-2-thione [(R)-barbarin] and (R)-5-phenyloxazolidin-2-one [(R)-resedine]. We conclude that a previously proposed generally higher defensive activity of BAR than NAS to M. brassicae larvae could not be confirmed. Indeed, the higher resistance of NAS-containing B. verna plants may be due to a combined effect of rather high concentrations of NAS and a relatively high myrosinase activity or other plant traits not investigated yet. 相似文献
10.
Jasmonic acid (JA) is a key hormone involved in plant defense responses. The effect of JA treatment of cabbage plants on their
acceptability for oviposition by two species of cabbage white butterflies, Pieris rapae and P. brassicae, was investigated. Both butterfly species laid fewer eggs on leaves of JA-treated plants compared to control plants. We show
that this is due to processes in the plant after JA treatment rather than an effect of JA itself. The oviposition preference
for control plants is adaptive, as development time from larval hatch until pupation of P. rapae caterpillars was longer on JA-treated plants. Total glucosinolate content in leaf surface extracts was similar for control
and treated plants; however, two of the five glucosinolates were present in lower amounts in leaf surface extracts of JA-treated
plants. When the butterflies were offered a choice between the purified glucosinolate fraction isolated from leaf surface
extracts of JA-treated plants and that from control plants, they did not discriminate. Changes in leaf surface glucosinolate
profile, therefore, do not seem to explain the change in oviposition preference of the butterflies after JA treatment, suggesting
that as yet unknown infochemicals are involved. 相似文献
11.
Sequestration of plant compounds by herbivorous insects as a defense against predators is well documented; however, few studies
have examined the effectiveness of sequestration as a defense against parasitoids. One assumption of the “nasty host” hypothesis
is that sequestration of plant defense compounds is deleterious to parasitoid development. We tested this hypothesis with
larvae of the sequestering sphingid Ceratomia catalpae, which is heavily parasitized by the endoparasitoid Cotesia congregata, despite sequestering high concentrations of the iridoid glycoside catalpol from their catalpa host plants. We collected C. catalpae and catalpa leaves from six populations in the Eastern US, and allowed any C. congregata to emerge in the lab. Leaf iridoid glycosides and caterpillar iridoid glycosides were quantified, and we examined associations
between sequestered caterpillar iridoid glycosides and C. congregata performance. Caterpillar iridoid glycosides were not associated with C. congregata field parasitism or number of offspring produced. Although wasp survival was over 90% in all populations, there was a slight
negative relationship between caterpillar iridoid glycosides and wasp survival. Iridoid glycosides were present in caterpillars
at levels that are deterrent to a variety of vertebrate and invertebrate predators. Thus, our results support the alternative
hypothesis that unpalatable, chemically defended hosts are “safe havens” for endoparasitoids. Future trials examining the
importance of catalpol sequestration to potential natural enemies of C. congregata and C. catalpae are necessary to strengthen this conclusion. 相似文献
12.
Carnivorous arthropods use volatile infochemicals emitted from prey-infested plants in their foraging behavior. Although several
volatile components are common among plant species, the compositions differ among prey–plant complexes. Studies showed that
the predatory mite Neoseiulus womersleyi is attracted only to previously experienced plant volatiles. In this study, we identified the attractant components in prey-induced
plant volatiles of two prey–plant complexes. N. womersleyi reared on Tetranychus kanzawai-infested tea leaves showed significant preference for a mixture of three synthetic compounds [mimics of the T. kanzawai-induced tea leaves volatiles: (E)-β-ocimene, (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), and (E,E)-α-farnesene] at a level comparable to that for T. kanzawai-induced tea plant volatiles. However, mixtures lacking any of these compounds did not attract the predatory mites. Likewise,
N. womersleyi reared on T. urticae-infested kidney bean plants showed a significant preference for a mixture of four synthetic compounds [mimics of the T. urticae-induced kidney bean volatiles: DMNT, methyl salicylate (MeSA), β-caryophyllene, and (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene] at a level comparable to that for T. urticae-induced kidney bean volatiles. The absence of any of the four compounds resulted in no attraction. These results indicate
that N. womersleyi can use at least four volatile components to identify prey-infested plants. 相似文献
13.
We report the comparative inducing effects of a phytopathogen and a herbivorous arthropod on the performance of an herbivore.
Tomato, Lycopersicon esculentum Mill., was used as the test plant, and tomato mosaic virus (ToMV) and corn earworm, Helicoverpa armigera Hübner, were used as the phytopathogen and herbivore, respectively. There were decreases in the efficiency of conversion
of ingested food and efficiency of conversion of digested food when H. armigera was reared on tomato plants that had been previously inoculated with ToMV. However, virus inoculation did not affect feeding
or oviposition preferences by H. armigera. In contrast, approximate digestibility, total consumption, relative growth rate, and relative consumption rate were lower
for fourth-instar H. armigera that fed on plants previously damaged by the same herbivore. Feeding and oviposition were both deterred for H. armigera that fed on previously damaged plants. The duration of development of H. armigera was also prolonged under this treatment. Infection by ToMV and feeding damage by H. armigera increased the host plant’s peroxidase and polyphenol oxidase activity, respectively, suggesting that the performance of H. armigera may be affected by the induced phytochemistry of the host plant. Overall, this study indicated that, in general, insect damage
has a stronger effect than ToMV infection on plant chemistry and, subsequently, on the performance of H. armigera. 相似文献
14.
Contact kairomones from adult southern green stink bugs, Nezara viridula (L.) (Heteroptera: Pentatomidae) that elicit foraging behavior of the egg parasitoid Trissolcus basalis (Wollaston) were investigated in laboratory experiments. Chemical residues from tarsi and scutella of N. viridula induced foraging by gravid female T. basalis. Residues from body parts of female N. viridula elicited stronger responses than those from the corresponding body parts of males. Deproteinized tarsi still elicited searching
responses from wasps, indicating that the kairomone was not proteinaceous. Hexane extracts of host cuticular lipids induced
searching responses from T. basalis, with a strong preference for extracts from female hosts. Extracts consisted primarily of linear alkanes from nC19 to nC34, with quantitative and qualitative differences between the sexes. Extracts of female N. viridula contained more nC23, nC24, and nC25 than the corresponding extracts from males, whereas nC19 was detected only in extracts from males. Direct-contact solid phase microextraction (DC-SPME) of N. viridula cuticle and of residues left by adult bugs walking on a glass plate confirmed gender-specific differences in nC19. Trissolcus basalis females responded weakly to a reconstructed blend of the straight-chain hydrocarbons, suggesting that minor components other
than linear alkanes must be part of the kairomone. Addition of nC19 to hexane extracts of female N. viridula significantly reduced the wasps’ arrestment responses, similar to wasps’ responses to hexane extracts of male hosts. Overall,
our results suggest that a contact kairomone that elicits foraging by T. basalis females is present in the cuticular lipids of N. viridula, and that the presence or absence of nC19 allows T. basalis females to distinguish between residues left by male or female hosts. The ecological significance of these results in the
host location behavior of scelionid egg parasitoids is discussed. 相似文献
15.
The vast majority of studies of plant indirect defense strategies have considered simple tritrophic systems that involve plant
responses to attack by a single herbivore species. However, responses by predators and parasitoids to specific, herbivore-induced,
volatile blends could be compromised when two or more different herbivores are feeding on the same plant. In Y-tube olfactometer
studies, we investigated the responses of an aphid parasitoid, Diaeretiella rapae (McIntosh) (Hymenoptera: Braconidae), to odors from cabbage plants infested with the peach-potato aphid Myzus persicae (Sulzer) (Homoptera: Aphididae), in both the presence and absence of a lepidopteran caterpillar, Plutella xylostella L. (Lepidoptera: Plutellidae). Female parasitoids chose aphid-infested plants over uninfested plants but did not distinguish
between caterpillar-infested and uninfested plants. When given a choice between odors from an aphid-infested plant and those
from a plant infested with diamondback moth larvae, they significantly chose the former. Furthermore, the parasitoids responded
equally to odors from a plant infested with aphids only and those from a plant infested with both aphids and caterpillars.
The results support the hypothesis that the aphid and the caterpillar induce different changes in the volatile profile of
cabbage plants and that D. rapae females readily distinguish between the two. Furthermore, the changes to the plant volatile profile induced by the caterpillar
damage did not hinder the responses of the parasitoid to aphid-induced signals. 相似文献
16.
Insect herbivores often induce plant volatile compounds that can attract natural enemies. Cotesia marginiventris (Hymenoptera: Braconidae) is a generalist parasitoid wasp of noctuid caterpillars and is highly attracted to Spodoptera exigua-induced plant volatiles. The plasticity of C. marginiventris associative learning to volatile blends of various stimuli, such as host presence, also has been shown, but little is known
about how this generalist parasitoid distinguishes between host species of varying suitability. Spodoptera exigua is an excellent host that yields high parasitoid emergence, while Trichoplusia ni serves as a sub-optimal host species due to high pre-imaginal wasp mortality. We have found that S. exigua and T. ni induce different volatile blends while feeding on cotton. Here, wind tunnel flight assays were used to determine the importance
of differentially induced volatiles in host-finding by C. marginiventris. We found that, while this generalist parasitoid wasp can distinguish between the two discrete volatile blends when presented
concurrently, a positive oviposition experience on the preferred host species (S. exigua) is more important than host-specific volatile cues in eliciting flight behavior towards plants damaged by either host species.
Furthermore, wasps with oviposition experience on both host species did not exhibit a deterioration in positive flight behavior,
suggesting that oviposition in the sub-optimal host species (T. ni) does not cause aversive odor association. 相似文献
17.
Sequestration of Furostanol Saponins by <Emphasis Type="Italic">Monophadnus</Emphasis> Sawfly Larvae
Prieto JM Schaffner U Barker A Braca A Siciliano T Boevé JL 《Journal of chemical ecology》2007,33(3):513-524
Sawfly larvae of the tribe Phymatocerini (Hymenoptera: Tenthredinidae), which are specialized on toxic plants in the orders
Liliales and Ranunculales, exude a droplet of deterrent hemolymph upon attack by a predator. We investigated whether secondary
plant metabolites from Ranunculaceae leaves are sequestered by phymatocerine Monophadnus species, i.e., Monophadnus alpicola feeding upon Pulsatilla alpina and Monophadnus monticola feeding upon Ranunculus lanuginosus. Moreover, two undescribed Monophadnus species were studied: species A collected from Helleborus foetidus and species B collected from Helleborus viridis. Comparative high-performance liquid chromatographic–photodiode array detection–electrospray ionization–mass spectrometric
analyses of plant leaf and insect hemolymph extracts revealed the presence of furostanol saponins in all samples. Larvae of
species A and B actively sequestered (25R)-26-[(α-l-rhamnopyranosyl)oxy]-22α-methoxyfurost-5-en-3β-yl O-β-d-glucopyranosyl-(1→3)-O-[6-acetyl-β-d-glucopyranosyl-(1→3)]-O-β-d-glucopyranoside (compound 1). This compound occurred at a 65- to 200-fold higher concentration in the hemolymph of the two species (1.6 and 17.5 μmol/g
FW, respectively) than in their host plant (0.008 and 0.268 μmol/g FW, respectively). In M. monticola, compound 1 was found at a concentration (1.2 μmol/g FW) similar to that in the host plant (1.36 μmol/g FW). The compound could not be
detected consistently in M. alpicola larvae where, however, a related saponin may be present. Additional furostanol saponins were found in H. foetidus and H. viridis, but not in the two Monophadnus species feeding on them, indicating that sequestration of compound 1 is a highly specific process. In laboratory bioassays, crude hemolymph of three Monophadnus species showed a significant feeding deterrent activity against a potential predator, Myrmica rubra ant workers. Isolated furostanol saponins were also active against the ants, at a concentration range similar to that found
in the hemolymph. Thus, these compounds seem to play a major role for chemical defense of Monophadnus larvae, although other plant secondary metabolites (glycosylated ecdysteroids) were also detected in their hemolymph. Physiological
and ecological implications of the sequestered furostanol saponins are discussed.
Dedicated to the memory of Professor Ivano Morelli (1940–2005) 相似文献
18.
Ageratum conyzoides L. weed often invades cultivated fields and reduces crop productivity in Southeast Asia and South China. However, intercropping this weed in citrus orchards may increase the population of predatory mite Amblyseius newsami, an effective natural enemy of citrus red mite Panonychus citri, and keep the population of P. citri at low and noninjurious levels. This study showed that A. conyzoides produced and released volatile allelochemicals into the air in the intercropped citrus orchard, and these volatiles influenced the olfactory responses of A. newsami and P. citri. At test temperature (25°C), A. conyzoides fresh leaves, its essential oil, and major constituents, demethoxy-ageratochromene, β-caryophyllene, α-bisabolene, and E-β-farnesene, attracted A. newsami and slightly repelled P. citri. Field experiments demonstrated that spraying A. conyzoides essential oil emulsion in an A. conyzoides nonintercropped citrus orchard increased the population density of A. newsami from below 0.1 to over 0.3 individuals per leaf, reaching the same level as in an A. conyzoides intercropped citrus orchard. However, this effect could not be maintained beyond 48 hr because of the volatility of the essential oil. In contrast, in the A. conyzoides intercropped citrus orchard, A. conyzoides plants continuously produced and released volatile allelochemicals and maintained the A. newsami population for a long time. The results suggest that intercropping of A. conyzoides not only made the citrus orchard ecosystem more favorable for the predatory mite A. newsami, but also that the volatile allelochemicals released from A. conyzoides regulated the population of A. newsami and P. citri. 相似文献
19.
Plant Growth Inhibition By <Emphasis Type="Italic">Cis</Emphasis>-Cinnamoyl Glucosides and <Emphasis Type="Italic">Cis</Emphasis>-Cinnamic Acid 总被引:3,自引:0,他引:3
Spiraea thunbergii Sieb. contains 1-O-cis-cinnamoyl--d-glucopyranose (CG) and 6-O-(4-hydroxy-2-methylene-butyroyl)-1-O-cis-cinnamoyl--d-glucopyranose (BCG) as major plant growth inhibiting constituents. In the present study, we determined the inhibitory activity of CG and BCG on root elongation of germinated seedlings of lettuce (Lactuca sativa), pigweed (Amaranthus retroflexus), red clover (Trifolium pratense), timothy (Phleum pratense), and bok choy (Brassica rapa var chinensis) in comparison with that of two well-known growth inhibitors, 2,4-dichlorophenoxyacetic acid (2,4-D) and (+)-2-cis-4-trans-abscisic acid (cis-ABA), as well as two related chemicals of CG and BCG, cis-cinnamic acid (cis-CA) and trans-cinnamic acid (trans-CA). The EC50 values for CG and BCG on lettuce were roughly one-half to one-quarter of the value for cis-ABA. cis-Cinnamic acid, which is a component of CG and BCG, possessed almost the same inhibitory activity of CG and BCG, suggesting that the essential chemical structure responsible for the inhibitory activity of CG and BCG is cis-CA. The cis-stereochemistry of the methylene moiety is apparently needed for high inhibitory activity, as trans-CA had an EC50 value roughly 100 times that of CG, BCG, and cis-CA. Growth inhibition by CG, BCG, and cis-CA was influenced by the nature of the soil in the growing medium: alluvial soil preserved the bioactivity, whereas volcanic ash and calcareous soils inhibited bioactivity. These findings indicate a potential role of cis-CA and its glucosides as allelochemicals for use as plant growth regulators in agricultural fields. 相似文献
20.
Plants emit volatile blends that may be quantitatively and/or qualitatively different in response to attack by different herbivores.
These differences may convey herbivore-specific information to parasitoids, and are predicted to play a role in mediating
host specificity in specialist parasitoids. Here, we tested the above prediction by using as models two parasitoids (Hymenoptera:
Braconidae) of cotton caterpillars with different degree of host specificity: Microplitis croceipes, a specialist parasitoid of Heliothis spp., and Cotesia marginiventris, a generalist parasitoid of caterpillars of several genera including Heliothis spp. and Spodoptera spp. We compared GC-EAD (coupled gas chromatography electroantennogram detection) responses of both parasitoid species to
headspace volatiles of cotton plants damaged by H. virescens (a host species for both parasitoids) vs. S. exigua (a host species for C. marginiventris). Based on a recent study in which we reported differences in the EAG responses of both parasitoids to different types of
host related volatiles, we hypothesized that M. croceipes (specialist) would show relatively greater GC-EAD responses to the herbivore-induced plant volatile (HIPV) components of
cotton headspace, whereas C. marginiventris (generalist) would show greater response to the green leaf volatile (GLV) components. Thirty volatile components were emitted
by cotton plants in response to feeding by either of the two caterpillars, however, 18 components were significantly elevated
in the headspace of H. virescens damaged plants. Sixteen consistently elicited GC-EAD responses in both parasitoids. As predicted, C. marginiventris showed significantly greater GC-EAD responses than M. croceipes to most GLV components, whereas several HIPV components elicited comparatively greater responses in M. croceipes. These results suggest that differences in the ratios of identical volatile compounds between similar volatile blends may
be used by specialist parasitoids to discriminate between host-plant and non-host-plant complexes. 相似文献