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1.
Summary. The ability to perceive and respond to phytochemicals that reliably indicate poor suitability of a potential host plant confers
a selective advantage to ovipositing female swallowtail butterflies. Papilio glaucus females are generalists that nonetheless do not oviposit on red bay (Persea borbonia: Lauraceae). Red bay is toxic to P. glaucus neonates but is commonly found in habitats alongside their principal host plant, Magnolia virginiana, in central Florida. The hypothesis that deterrent compounds present in the leaves of red bay mediate its rejection by P. glaucus was evaluated in our study. Florida populations of P. glaucus did not oviposit on host leaves sprayed with the methanol extract of red bay foliage, although they accepted solvent-treated
and untreated tulip tree leaves in 3 choice bioassays. Additionally, tulip tree leaves sprayed with methanolic extracts of
red bay also deterred oviposition by P. glaucus females from Ohio, Kentucky and Pennsylvania, although these populations do
not naturally encounter red bay. Clearly, deterrent compounds found within this non-host are the basis of its rejection by
populations of P. glaucus and such recognition is fundamental to the species, not just a reflection of local adaptations.
Received 2 April 1999; accepted 11 June 1999. 相似文献
2.
Summary. While many marine molluscs have been suggested to use aposematic coloration to avoid predation, few studies have tested the
ability of marine predators to learn to associate colors with distasteful prey. In field experiments, we tested the ability
of two populations of reef fishes to discriminate among red, yellow, and black artificial nudibranch models when one color
was paired with a feeding deterrent. We offered fishes (1) the models without any feeding deterrents, (2) the models with
a feeding deterrent coated onto one color, and (3) the models without deterrents again. If reef fishes learn to associate
colors with noxious prey, we expected the color paired with the feeding deterrent to be eaten less frequently in the final
assay than the initial assay. In both populations, fishes formed clear associations between color and feeding deterrence.
However, when the experiment was repeated in one population, changing the color paired with the feeding deterrent, fishes
did not form an association between color and feeding deterrence. In this case, prior learning may have affected subsequent
trials. Our study indicates that common colors of nudibranchs are recognizable by fishes and can be associated with noxious
prey.
Received 24 September 1998; accepted 18 December 1998. 相似文献
3.
An on-going, Caribbean-wide epizootic affecting sea fan corals (Gorgonia spp.) is caused by the fungus Aspergillus sydowii (Thom et Church). We examined the role of crude extracts in resistance of two species of sea fans, Gorgonia ventalina (L.) and G. flabellum (L.), against A. sydowii and a bacterial pathogen of fish, Listonella anguillarum (MacDonell et Colwell). Sea fans were collected in January 1997 from San Salvador, Bahamas, and in June 1997 and January
1998 from Alligator Reef, Florida Keys, USA. Crude extracts from both species were tested to determine concentrations inhibiting
germination of A. sydowii spores. Crude extracts from both species inhibited spore germination at concentrations as low as 1.5 mg ml−1; most samples were active at 5 to 10 mg ml−1. These concentrations are within the range estimated in living tissue and were higher in healthy colonies suggesting their
role in mediating disease susceptibility. We also detected within-colony gradients in antifungal activity, which varied with
the disease state of the colony. In healthy sea fans, resistance was highest at colony edges and lowest in medial and central
regions of the colony. Among sea fans with lesions in the colony center, resistance in tissue from proximal and medial regions
was as high as tissue from the colony edge (i.e. distal region). The increase in antifungal activity suggests an inducible
response by the coral host to the fungal pathogen. This response is most evident among sea fans with lesions in the colony
center and not among colonies with lesions at the edge. Antibacterial activity of crude extracts against L. anguillarum was highest at the colony edge but did not vary with disease state or tissue location.
Received: 10 March 1999 / Accepted: 10 November 1999 相似文献
4.
Nancy L. Douglas Kerri M. Mullen Stephanie C. Talmage C. Drew Harvell 《Marine Biology》2007,150(6):1137-1144
Chitinases are involved in defense against chitinaceous pathogens in both invertebrates and vertebrates. This study investigated
whether sea fan corals, Gorgonia ventalina (Linnaeus) collected from the Florida Keys between the summer of 2002 and the summer of 2005 contain chitinases, and whether
these enzymes could serve an analogous protective role against the fungal pathogen, Aspergillus sydowii (Thom et Church). Crude extracts of healthy sea fans contained detectible levels of exochitinase activity in an in vitro
microplate assay using fluorogenic substrates. The exochitinase levels decreased upon injury, agitation, or manipulation of
the tissue. A concurrent, transient increase of exochitinase in the surrounding water suggests that sea fans release chitinases
as a response to these stresses. By contrast, endochitinase was detected in only 2 of 15 sea fans (13%), suggesting a high
degree of variation for this enzyme. Sea fan chitinase-containing seawater and anion exchange chromatography fractions were
both active against A. sydowii in an absorbance-based antifungal assay. The presence of chitinases in sea fan extracts, their release into the surrounding
water upon stress, and their activity against A. sydowii suggests that further study of these enzymes in coral stress responses is warranted. 相似文献
5.
Karen M. Kester Steven C. Peterson Frank Hanson D. Michael Jackson R. F. Severson 《Chemoecology》2002,12(1):1-10
Summary. Field observations indicated that hornworms select feeding sites non-randomly on tobacco. We tested the hypotheses that differences
in feeding site locations of larvae of Manduca
sexta L. and Manduca
quinquemaculata (Haworth) (Lepidoptera: Sphingidae) on tobacco could be explained by differential nicotine concentrations within plants and
leaves, species-specific responses to nicotine, or pressure exerted by natural enemies. Results showed that third-instar larvae
of M. sexta fed more proximally and centrally on the leaf, whereas M. quinquemaculata fed more distally. Within-plant selection of leaves did not differ; both species selected leaves in the middle region of
the plant. Nicotine concentrations in a high nicotine genotype, NC95, varied within each leaf, increasing 2—3 fold from the
basal to apical portion of the leaf, and within each plant, increasing 7—10 fold from the first fully expanded leaf to the
twelfth (lowest) leaf. In laboratory bioassays, both Manduca species responded to nicotine as a feeding deterrent. Electrophysiological studies demonstrated that gustatory organs of
both species responded to nicotine at concentrations found in tobacco leaves and that M. quinquemaculata generally showed a less vigorous response to nicotine than M. sexta. Field mortality of M. sexta due to parasitism by Cotesia
congregata (Say) and to parasitism and predation combined differed among feeding sites; predation alone did not. Results suggest that
although nicotine concentration and species specific responses to nicotine play a role in determining feeding site locations,
pressure exerted by natural enemies, especially parasitism by C. congregata, is more important.
Received 22 February 2000; accepted 20 July 2001. 相似文献
6.
Summary. Many secondary plant compounds are involved in defense against both insect herbivores and pathogens. Two secondary plant
compounds of Plantago lanceolata, the iridoid glycosides catalpol and its precursor aucubin, are well known for their deterrent effects on generalist and
non-adapted specialist insect herbivores. We tested the effects of these compounds on the in-vitro growth of a specialist
and generalist fungal pathogen of this host species. Two chemical forms of these iridoids were tested. The glycosides and
their aglycones, the products of enzymatic conversion by specific $/Beta$-glucosidase enzymes. The glycosides enhanced growth
of both the specialist fungus Diaporthe adunca and the generalist fungus Fusarium moniliforme var. subglutinans. The positive effect of these glycosides on the generalist fungus is in sharp contrast with the generally negative effects
of these glysosides on generalist insect herbivores. The aglycones of aucubin and catalpol reduced the growth of the specialist
fungus D. adunca, but, contrary to expectation, enhanced the growth of the generalist fungus F. moniliforme var. subglutinans. Effects of aucubin on D. adunca were stronger than effects of catalpol. This was true both for the growth stimulating effects of the glycosides and for the
fungitoxic effects of the aglycones. We therefore expect that the effects of these iridoids in P. lanceolata on the specialist fungus will strongly depend on the ratio between catalpol and its precursor aucubin and the chemical form
(glycoside or aglycone) in which these compounds are encountered by the fungus during growth. Our results suggest that iridoid
glycosides in P. lanceolata can be used as defense against both herbivores and pathogens, but that their effects are highly specific with respect to
the natural enemy species that is encountered.
Received 11 April 2002; accepted 9 August 2002 相似文献
7.
Summary. Sequestration of plant toxins in herbivores is often
correlated with aposematic coloration and gregarious behaviour. Larvae
of Pieris brassicae show these conspicuous morphological and behavioural
characteristics and were thus suggested to sequester glucosinolates that
are characteristic secondary metabolites of their host plants. P. rapaeare camouflaged and solitary, and are thus not expected to sequester. To
test this hypothesis and to check the repeatabi-lity of a study that did
report the presence of the glucosinolate sinigrin in P. brassicae,
larvae were reared on three species of Brassicaceae (Sinapis alba,
Brassica nigra and Barbarea stricta), and different leaf and insect
samples were taken for glucosinolate analysis. The major host plant
glucosinolates could only be found in traces or not at all in larval
haemolymph, bled or starved larvae, faeces or pupae of both species or
P. brassicae regurgitant. Haemolymph of both Pieris spp. was not
rejected by the ant Myrmica rubra in dual-choice assays; the regurgitant
of P. brassicae was rejected. This suggests the presence of compounds
other than glucosinolates that might be sequestered in or produced by P.
brassicae only. In faeces of both Pieris spp. a compound which yielded
4-hydroxybenzylcyanide (HBC) upon incubation with sulfatase was detected
in high concentrations when larvae had been reared on S. alba. This
compound may be derived from hydrolysis of sinalbin, the main
glucosinolate of that plant. The unidentified HBC progenitor was
apparently not sequestered in the two Pieris spp., and was not detected
in faeces of larvae reared on B. nigra or B. stricta.
Received 18 July 2002; accepted 11 September 2002. 相似文献
8.
Summary. The capacity of benzoxazolinone metabolization of dicotyledonous species characteristic for the former vegetation classes
Secalietea (grain field weed communities) and Chenopodietea (hoed vegetable communities) was estimated by the production of
BOA-6-OH, BOA-6-β-O-glucoside, and BOA-N-glucoside. Except for Urtica urens, Galinsoga ciliata, and Polygonum aviculare (Chenopodietea), all species tested were able to synthesize BOA-6-OH, its glucoside, and BOA-N-glucoside, but effectiveness
of BOA metabolism differed highly depending on species and plant organ. There was no correlation between bacterial phenoxazinone
production and appearance of metabolites in the plants. Bioassays demonstrated that N-glucosylation is more efficient in BOA
detoxification than O-glucosylation. The intermediate BOA-6-OH, however, is more harmful than BOA itself. It is therefore
assumed that the ability to synthesize BOA-N-glucoside reduces the sensitivity to BOA strikingly. Since the detoxification
capacity did not correlate with the taxonomic position, the affiliation of the species tested with the corresponding plant
communities was taken into consideration. Evidently, the ecobiochemical potential of species to detoxify benzoxazolinone,
regarded as an essential secondary compound in rye and wheat fields, reflects their occurrence in those plant associations.
The ability to cope with the compound could be the result of co-evolutionary processes and presents a hidden aspect of allelopathic
interaction.
Received 4 January 1999; accepted 14 June 1999. 相似文献
9.
Susanna Andersson 《Chemoecology》2003,13(1):13-20
Summary. To better understand the biological role of floral scents for
butterflies, electrophysiological responses to floral scents were
investigated using combined gas chromatography and electroantennographic
detection (GC-EAD). The antennal responses of three butterfly species,
Aglais urticae L. (Nymphalidae), Inachis io L. (Nymphalidae), and
Gonepteryx rhamni L. (Pieridae) to floral scent compounds from both
natural and synthetic mixtures were examined. Floral scents were
collected from the butterfly nectar plants Cirsium arvense (L.)
(Asteraceae), and Buddleja davidii Franchet cv. (Loganicaeae) with
dynamic head-space methods on Tenax-GR and eluted with pentane. These
eluates, composed of natural floral scent blends, represent an array of
compounds in their natural state. In the GC-EAD analyses eleven
compounds were identified from C. arvense with the benzenoid compound
phenylacetaldehyde in highest abundance. Seventeen compounds were
identified from B. davidii with the irregular terpene oxoisophorone in
highest abundance. Thirty-nine synthetic floral scent compounds were
mixed in pentane, in equal amounts; about 35 ng were allowed to reach
the antennae. The butterflies showed antennal responses to most of the
floral scent compounds from both natural and synthetic blends except to
the highly volatile monoterpene alkenes. Certain benzenoid compounds
such as phenylacetaldehyde, monoterpenes such as linalool, and irregular
terpenes such as oxoisophorone, were emitted in relatively large amounts
from C. arvense and B. davidii, and elicited the strongest antennal
responses. These compounds also elicited strong antennal responses when
present in the synthetic scent blends. Thus, the butterflies seem to
have many and /or sensitive antennal receptors for these compounds,
which points to their biological importance. Moreover, these compounds
are exclusively of floral scent origin. For B. davidii, which depends
highly on butterflies for pollination, the exclusive floral scent
compounds emitted in high abundance could be the result of an adaptive
pressure to attract butterflies.
Received 2 Septemter 2001; accepted 9 September 2002. 相似文献
10.
K. M. Mullen C. D. Harvell A. P. Alker D. Dube E. Jordán-Dahlgren J. R. Ward L. E. Petes 《Marine Biology》2006,149(6):1355-1364
Knowledge of host range and mechanisms of disease resistance is fundamental to predicting impacts and spread of marine diseases. Prevalence of signs of aspergillosis, caused by the terrestrial fungus Aspergillus sydowii, was assessed in the Yucatan among three species of sea fan: Gorgonia ventalina, G. cf. mariae, and G. flabellum. The Yucatan is unusual in that ranges of all three sea fan species overlap at many sites along a cline of increasing depth, allowing us to evaluate potential causes of differing prevalence among species. Signs of aspergillosis were observed in all the three species. However, the prevalence of infection in G. cf. mariae, a deep-water species, was consistently low even at sites where G. ventalina was common and had moderate levels of infection. Because G. cf. mariae is a relatively small-stature sea fan, we compared the prevalence of signs in G. cf. mariae to a subset of comparatively sized G. ventalina. G. ventalina had a significantly higher prevalence of aspergillosis, indicating that size does not explain the lower prevalence in G. cf. mariae. Prevalence of disease signs on the shallow-water G. flabellum was also significantly higher than G. cf. mariae, but did not differ from G. ventalina. To test the hypothesis that higher chemical resistance accounts for the low prevalence of disease in G. cf. mariae, we measured the response of A. sydowii in culture to antifungal extracts from each sea fan species. Significantly lower fungal growth rates on extracts of G. cf. mariae than G. ventalina support the hypothesis that G. cf. mariae is more chemically resistant to aspergillosis. When comparing sea fan disease across different regions of the Yucatan, we detected significantly higher prevalence in G. ventalina near Akumal than further north near Cozumel and Puerto Morelos. In Akumal, there was a strong positive correlation between sea fan size and disease, with the largest fans showing the highest prevalence and severity in all three species. In addition, prevalence of aspergillosis in G. ventalina was density-dependent in Ak. 相似文献
11.
Summary. We tested the hypothesis that aggregation behaviour of the
firebrat, Thermobia domestica (Packard) (Thysanura: Lepismatidae), an
inhabitant of enclosed microhabitats, is mediated, at least in part, by
a pheromone. Individual insects were released into the central chamber
of a 3-chambered olfactometer and test stimuli were placed in lateral
chambers. Paper discs previously exposed for 3 days to 10 female, male,
or juvenile T. domestica were all preferred by female, male, or juvenile
T. domestica over unexposed paper discs, indicating the presence of an
aggregation/arrestment pheromone. In additional experiments, frass and
scales from female T. domestica, tested singly and in combination,
proved not to be the source of the pheromone. Physical contact was
required for pheromone recognition, indicating that the pheromone
arrests rather than attracts conspecifics. Arrestment by the
long-tailed silverfish, Ctenolepisma longicaudata Escherich
(Thysanura: Lepismatidae), but not by the common silverfish, Lepisma
saccharina L. (Thysanura: Lepismatidae), to T. domestica exposed
paper discs suggests closer phylogenetic relatedness between C.
longicaudata and T. domestica, than between C.
longicaudata and L. saccharina. Whether C.
longicaudata or L. saccharina produce an aggregation
signal, and whether T. domestica respond to this signal is unknown.
Received 10 June 2002; accepted 30 September 2002. 相似文献
12.
Three procedures for the extraction of coral lipids were compared and a rapid and effective method for future use is suggested. This method was used to measure the lipid content of the branching coral Porites porites (Pallas) and the massive corals Montastrea annularis (Ellis and Solander) and Siderastrea siderea (Ellis and Solander) during July and August 1991. P. porites and M. annularis were sampled on two fringing reefs, each characterised by different water quality affecting light transmission, and at depths of down to 30 m on a barrier reef on the west coast of the island. m. annularis contained, on average, 29% of dry weight as lipid, and there were no significant differences in lipid levels between corals sampled on either fringing reef at 3 and 6 m, or between fringing reefs and the barrier reef at 13, 20 or 30 m depth. Five samples were also taken from a single massive colony of S. siderea at 3 m on a fringing reef and at 13, 20 and 30 m depth on the barrier reef. Values for lipid ranged from 26 to 35% of dry tissue weight. P. porites from 3 and 6 m depth on both fringing reefs contained the same amount of lipid (11% of dry tissue weight). However, at 13 m depth on the barrier reef this coral contained significantly less lipid (8.5% of dry tissue weight). This difference may be attributable to a higher nutritional intake by P. porites on the fringing reefs. 相似文献
13.
Widespread thermal anomalies in 1997-1998, due primarily to regional effects of the El Niño-Southern Oscillation and possibly augmented by global warming, caused severe coral bleaching worldwide. Corals in all habitats along the Belizean barrier reef bleached as a result of elevated sea temperatures in the summer and fall of 1998, and in fore-reef habitats of the outer barrier reef and offshore platforms they showed signs of recovery in 1999. In contrast, coral populations on reefs in the central shelf lagoon died off catastrophically. Based on an analysis of reef cores, this was the first bleaching-induced mass coral mortality in the central lagoon in at least the last 3,000 years. Satellite data for the Channel Cay reef complex, the most intensively studied of the lagoonal reefs, revealed a prolonged period of elevated sea-surface temperatures (SSTs) in the late summer and early fall of 1998. From 18 September to 1 October 1998, anomalies around this reef averaged +2.2°C, peaking at 4.0°C above the local HotSpot threshold. In situ temperature records from a nearby site corroborated the observation that the late summer and early fall of 1998 were extraordinarily warm compared to other years. The lettuce coral, Agaricia tenuifolia, which was the dominant occupant of space on reef slopes in the central lagoon, was nearly eradicated at Channel Cay between October 1998 and January 1999. Although the loss of Ag. tenuifolia opened extensive areas of carbonate substrate for colonization, coral cover remained extremely low and coral recruitment was depressed through March 2001. High densities of the sea urchin Echinometra viridis kept the cover of fleshy and filamentous macroalgae to low levels, but the cover of an encrusting sponge, Chondrilla cf. nucula, increased. Further increases in sponge cover will impede the recovery of Ag. tenuifolia and other coral species by decreasing the availability of substrate for recruitment and growth. If coral populations are depressed on a long-term basis, the vertical accretion of skeletal carbonates at Channel Cay will slow or cease over the coming decades, a time during which global-warming scenarios predict accelerated sea-level rise. 相似文献
14.
Preferences of six leaf beetle species among qualitatively different leaf age classes of three Salicaceous host species 总被引:2,自引:0,他引:2
Arsi Ikonen 《Chemoecology》2002,12(1):23-28
Summary. As Salicaceous plants produce new leaves for a prolonged period of time, they expose a wide range of differentially aged
leaves to herbivores during the growing season. In this work, I show that young leaves of three Salicaceous species, Populus tremula L., Salix phylicifolia L. and S. pentandra L., contain more nitrogen than conspecific old leaves. In P. tremula and S. pentandra young leaves also contained more low-molecular weight secondary compounds, phenolic glucosides. Leaves of S. phylicifolia did not contain phenolic glucosides in detectable amounts. Furthermore, in P. tremula and S. pentandra young leaves contained less polymeric digestability-reducing phenolics, condensed tannins, than old leaves. In S. phylicifolia, higher concentrations of condensed tannins were found in young leaves. In laboratory feeding trials with six leaf beetle
species, young leaves of the studied plants were invariably preferred in all tested herbivore × host species combinations.
In particular, it is remarkable that three leaf beetle species with known different overall relationships to phenolic glucosides
equally preferred more glucoside-containing young S. pentandra leaves over conspecific old ones. Four beetle species were found to prefer young leaves of S. phylicifolia despite the higher content of condensed tannins in young leaves. These results indicate that the general preference of leaf
beetles for young leaves of Salicaceous plants probably does not primarily result from variable distribution of secondary
compounds. Apparently, the preference for young leaves is fundamentally due to variation in leaf nutritive traits, such as
nitrogen content.
Received 9 February 2001. 相似文献
15.
Susanna Andersson 《Chemoecology》2003,13(1):1-11
Summary. For butterflies to be efficient foragers, they need to
be able to recognize rewarding flowers. Flower signals such as colours
and scents assist this recognition process. For plant species to attract
and keep butterflies as pollinators, species-specific floral signals are
crucial. The aim of this study is to investigate foraging responses to
floral scents in three temperate butterfly species, Inachis io L.
(Nymphalidae), Aglais urticae L. (Nymphalidae), and
Gonepteryx rhamni L. (Pieridae), in behavioural choice
bioassays. The butterflies were allowed to choose bet-ween flower models
varying in scent and colour (mauve or green). Flowers or vegetative
parts from the plants Centaurea scabiosa L. (Asteraceae),
Cirsium arvense (L.) (Asteraceae), Knautia arvensis (L.)
(Dipsacaceae), Buddleja davidii Franchet (Loganicaeae), Origanum vulgareL. (Lamiaceae), Achillea millefolium L. (Asteraceae), and
Philadelphus coronarius L. (Hydrangiaceae) were used as scent
sources. All visits to the models — those that included probing and
those that did not — were counted, as was the duration of these
behaviours. Both flower-naive and flower-experienced (conditioned to
sugar-water rewards, the colour mauve, and specific floral scents)
butterflies were tested for their preference for floral versus
vegetative scents, and to floral scent versus colour. The butterflies
were also tested for their ability to switch floral scent preferences in
response to rewards. Flower-naive butterflies demonstrated a preference
for the floral scent of the butterfly-favourable plants C.
arvense and K. arvensis over the floral scent of the non-favourable
plants Achillea millefolium (Asteraceae), and Philadelphus
coronarius cv. (Hydrangiaceae). Most of the butterflies that were
conditioned to floral scents of either C. arvense, K. arvensis,
or B. davidii readily switched theirfloral scent preferences to
the one most recently associated with reward, thus demonstrating that
floral scent constancy is a result from learning. These findings suggest
that these butterflies use floral scent as an important cue signal to
initially identify and subsequently recognize and distinguish among
rewarding plants.
Received 2 September 2001; accepted 9 September 2002. 相似文献
16.
17.
Effects of hydrolysable tannins on a herbivorous insect: fate of individual tannins in insect digestive tract 总被引:2,自引:0,他引:2
Summary. We investigated the effects of four chemically characterised galloylglucoses (GGs, a subgroup of hydrolysable tannins) and
their hydrolysis product, gallic acid (GA), on consumption and performance of larvae of the autumnal moth Epirrita autumnata. Larvae were fed with birch (Betula pubescens) leaves that had been painted individually with each of the compounds at two levels, 5 and 20 mg/g. In addition, we investigated
the fates of the leaf-painted GGs and GA in the E. autumnata digestive tract by comparing phenolics in leaves consumed and in faeces. In general, GGs reduced leaf consumption by E. autumnata during the second and fourth instars, although there was high compound- and instar-specific variation. However, GGs did not
affect the leaf consumption rates by the most voracious fifth instar larvae. This resulted in approximately the same loss
of total biomass by the experimental tree, regardless of the nature and level of GGs enriched to its foliage. The characteristic
fate of hydrolysable tannins, i.e. hydrolysis, was evidenced in the larval digestive tract for three of the four leaf-painted
GGs. In addition to hydrolysis, the almost total absence of GGs in larval faeces was presumably related to the oxidation of
GGs. The dose-dependent excretion percentage of ingested GA showed that it's faecal content should not be used, although it
commonly is, to calculate the level of GG hydrolysis. Moreover, by comparing the non-uniform appearance of faecal tetragalloylglucoses,
whether ingested as such or hydrolysed from pentagalloylglucose, we concluded that a major part of oxidation of GGs occurs
before their hydrolysis in the digestive tract of E. autumnata. Criticism against the common use of tannic acid, a heterogeneous mixture of GA and GGs, in ecological studies is presented.
Received 15 May 2002; accepted 16 July 2002 相似文献
18.
Variability in the chemical defense of the sponge Chondrilla nucula against predatory reef fishes 总被引:2,自引:0,他引:2
Chondrilla nucula is a common Caribbean demosponge that grows in a range of habitats, from coral reefs to mangrove swamps. On reefs, C. nucula grows as a thinly encrusting sheet, while in mangrove habitats it surrounds submerged mangrove roots as fleshy, lobate clumps.
Previous feeding experiments using predatory reef fish revealed a high degree of variability in the chemical defenses of C. nucula. The present study was undertaken to determine whether a relationship exists between habitat, growth form, and chemical defense
of C. nucula. Both laboratory and field feeding-assays of crude extracts confirmed that C. nucula possesses a chemical defense with high intercolony variability, but there was no significant variation in feeding deterrency
between reef and mangrove habitats at either geographic location (Bahamas and Florida). Extracts of C. nucula collected during September and October 1994 from the Bahamas were significantly more deterrent than those collected during
August 1993, May 1994, and May 1995 from Florida, and extracts of these spring and summer Florida collections were more deterrent
than extracts of C. nucula collected in December 1994 and February 1995 in the same locations. There was no evidence that deterrent compounds were concentrated
in the surface tissues of the sponge, or that chemical defense could be induced by simulated predation. Laboratory and field
assays of the fractionated crude extract revealed that feeding deterrency was confined to the most polar metabolites in the
extract. Field transplants were used to determine whether predation influenced the growth form of C. nucula. Uncaged sponges transplanted from the mangrove to the reef were readily consumed by spongivorous reef fishes. Lobate mangrove
sponges became thinner after being caged on the reef for 3 mo, but encrusting reef sponges did not become thicker after being
caged in the mangroves for the same period of time. Reef sponges that were caged for 3 to 15 mo thickened by only a small
amount (<1 mm) compared to uncaged and open-caged (i.e. in cages lacking tops) sponges. Simulated bite marks on both reef
and mangrove sponges were repaired at a rapid rate (0.8 to 1.6 mm d−1). Fish predation has an important impact on the distribution and abundance of C. nucula, but the thin growth form common to reef environments may be more the result of hydrodynamics than of grazing by spongivorous
fishes.
Received: 6 October 1997 / Accepted: 19 March 1998 相似文献
19.
Andrés González Frank C. Schroeder Athula B. Attygalle Aleš Svatoš Jerrold Meinwald Thomas Eisner 《Chemoecology》1999,9(3):105-112
Summary. Female Photuris fireflies sequester defensive steroidal pyrones (lucibufagins) from male fireflies of the genus Photinus. Lucibufagin analyses of Photuris females and Photinus ignitus males show that the lucibufagin mixtures of predator and prey differ in their composition. Analyses of whole body extracts
showed that P. ignitus males contain a mixture of eight non-glycosylated lucibufagins, composed mostly of compounds with two oxygenated positions
in the steroidal A-ring (C-3, C-5). After feeding on P. ignitus males, Photuris females contain six major lucibufagins. Three of these compounds are not present in the prey, including the novel lucibufagin
glycoside 5β,11α-dihydroxy-12-oxo-3β-O-β-D-xylopyranosylbufalin, and two other lucibufagins with a trioxygenated A-ring (C-2,
C-3, C-5). These results indicate that Photuris females transform the sequestered lucibufagins both by glycosylation and oxidation, which could affect the systemic transportability
of these compounds due to an increase in their polarity.
Received 18 February 1999; accepted 19 April 1999. 相似文献
20.
Summary. The bolas spider, Mastophora hutchinsoni, attracts Lacinipolia renigera and Tetanolita mynesalis males by mimicking the female moth sex pheromones. However, as the prey species use completely different pheromone blends
we conducted experiments to determine how this is accomplished by the predator. The periodicity of L. renigera mate-seeking activities occurs early in the scotophase, whereas male T. mynesalis are active late at night, corresponding with periods when these moths are captured by the spider. The pheromone blend of
early-flying L. renigera interferes with attraction of late-flying T. mynesalis to its pheromone in a dose-dependent manner, suggesting the spider must always produce a single sub-optimal “compromise”
blend for both species or that it adjusts its allomonal blend to optimize capture of the respective prey species at different
times during the night. We delayed (L. renigera) or advanced (T. mynesalis) the periodicity of male activity through photoperiodic manipulation and found that the bolas spider attracted both prey
species outside their normal activity windows. These results support the idea that bolas spiders produce components of both
species at all times rather than producing the pheromone of each prey species at different times of the night. However, using
coupled gas chromatography-electroantennography, we also demonstrated that the spider decreases its emission of the L. renigera pheromone over the course of the night. This modification should reduce the behavioral antagonism of the L. renigera pheromone on T. mynesalis males and increase the predator's success of attracting T. mynesalis during this prey's normal activity window late at night.
Received 13 October 2001; accepted 28 December 2001. 相似文献