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1.
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
2.
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
3.
Martine Hossaert-McKey Catherine Soler Bertrand Schatz Magali Proffit 《Chemoecology》2010,20(2):75-88
Mutualisms are interspecies interactions in which each participant gains net benefits from interacting with its partner. In
nursery pollination mutualisms, pollinators reproduce within the inflorescence they pollinate. In these systems, each partner
depends directly on the other for its reproduction. Therefore, the signal responsible for partner encounter is crucial in
these horizontally transmitted mutualisms, in which the association between specific partners must be renewed at each generation.
As in many other interspecies interactions, chemical signals are suspected to be important in the functioning of these mutualisms.
We synthesized and compared the published data available on the role of floral scents in the functioning of the 16 known independently
evolved nursery pollination mutualisms. So far, attraction of pollinators to their specific hosts has been investigated in
only seven of these systems, and the majority of the studies have been conducted on one of them, fig/fig wasp interactions.
While such unevenness of the information limits the potential for meta-analysis, some patterns emerge from this review concerning
the role of flower volatiles in maintaining the specificity of pollinator attraction, in signaling the appropriate phenological
stage for pollinator visit, in attracting the pollinator toward the rewardless sex in dioecious plant species and in aiding
the location and exploitation of resources by parasites and predators associated with these mutualisms. Finally, we highlight
new perspectives on the evolution of signals in these diversified systems depending on the age and the degree of specificity
of the interaction, and on the effect of phylogenetic inertia on the evolutionary dynamics of plant signals. 相似文献
4.
Claire Suchet Laurent Dormont Bertrand Schatz Martin Giurfa Valérie Simon Christine Raynaud Jérôme Chave 《Behavioral ecology and sociobiology》2011,65(5):1015-1027
Two wild subspecies of snapdragon, Antirrhinum majus, subspecies pseudomajus and striatum, differ in floral color and can be visually discriminated by insect visitors. The extent to which olfactory cues derived
from floral scents contribute to discrimination between snapdragon subspecies is however unknown. We tested whether these
two subspecies differ in floral scent and whether these olfactory differences are used by bumblebees (Bombus terrestris) to discriminate between them. We grew individuals of both subspecies, collected from a total of seven wild populations,
under controlled conditions. We quantified the volatile organic compounds (VOCs) emitted by the flowers using gas-chromatography/mass-spectrometry/flame-ionization-detection.
We studied antennal detection of VOCs by bumblebees, by means of electroantennogram study (EAG). We also performed behavioral
experiments in a Y-maze to determine the innate response of bumblebees to the main floral VOCs emitted by our snapdragon subspecies.
The floral scent of Antirrhinum majus pseudomajus contained three volatile benzenoids absent in the floral scent of Antirrhinum majus striatum. One of them, acetophenone, contributed over 69% of the absolute emissions of A. majus pseudomajus. These benzenoids elicited a significantly higher EAG response compared with other VOCs. In the Y-maze, bumblebees were significantly
less attracted by acetophenone, suggesting an aversive effect of this VOC. Our findings indicate that bumblebees are able
to discriminate between the two Antirrhinum majus subspecies. Differences in flower scent between these subspecies and olfactory bumblebee preferences are discussed in the
light of biochemical constraints on VOCs synthesis and of the role of flower scent in the evolutionary ecology of A. majus. 相似文献
5.
A mutualism with a native membracid facilitates pollinator displacement by Argentine ants 总被引:3,自引:0,他引:3
The loss of biodiversity and associated ecosystem services are major threats posed by the spread of alien invasive species. Invasive ants are frequently associated with declines in the diversity of ground-dwelling arthropods but also may affect plants through their attraction to floral nectar and tending of hemipterans. Protea nitida is a tree native to the South African fynbos that hosts a native membracid, Beaufortiana sp., which is tended by ants. Here I compare Argentine ants (Linepithema humile) to native ants in their attraction to P. nitida inflorescences in the presence and absence of the membracid, and their effects on other floral arthropod visitors, seed set, and ovule predation. Argentine ant discovery of inflorescences increased at least 13-fold when membracids were present on the branch, whereas native ant discovery of inflorescences was only doubled by membracid presence at one site in one study year and was unaffected in the other three site-years. Excluding Argentine ants from inflorescences resulted in an increase in several arthropod taxa and potential pollinators; native ant exclusion had no positive effects. Thus the mutualism between Argentine ants and the membracid is facilitating pollinator deterrence by the ants. Though Argentine ants were not associated with a decline in P. nitida seed set or ovule predation, declines in generalist insect pollinators may have ramifications for the 83% of fynbos plants that are insect pollinated. Pitfall traps showed that Argentine ants were not more abundant than native ants in non-invaded sites. Focusing only on abundance on the ground and displacement of ground-dwelling arthropod fauna may lead to an underestimate of the effects of invasive ants on their adopted communities. 相似文献
6.
Johannes Stökl Robert Twele Dirk H. Erdmann Wittko Francke Manfred Ayasse 《Chemoecology》2007,17(4):231-233
Summary.
Ophrys flowers mimic the female produced sex pheromone of their pollinator species to attract males for pollination. The males try
to copulate with the putative female and thereby pollinate the flower. Using electrophysiological and chemical analyses, floral
volatiles released by O. iricolor as well as the female sex pheromone of its pollinator species, Andrena morio are investigated. Overall, 38 peaks comprising 41 chemical compounds, were found to release reactions in the antennae of
male A. morio bees. Analyses using coupled gas chromatography-mass spectrometry revealed the presence of alkanes and alkenes with 20 to
29 carbon atoms, aldehydes (C9 to C24) and two esters. Almost all of those compounds were found in similar proportions in
both, the floral extracts of O. iricolor and cuticle surface extracts of A. morio females. The pattern of biologically active volatiles described here is very similar to that used by other Ophrys species pollinated by Andrena males. 相似文献
7.
Abstract: Concerns about pollinator declines have grown in recent years, yet the ability to detect changes in abundance, taxonomic richness, and composition of pollinator communities is hampered severely by the lack of data over space and time. Citizen scientists may be able to extend the spatial and temporal extent of pollinator monitoring programs. We developed a citizen‐science monitoring protocol in which we trained 13 citizen scientists to observe and classify floral visitors at the resolution of orders or super families (e.g., bee, wasp, fly) and at finer resolution within bees (superfamily Apoidea) only. We evaluated the protocol by comparing data collected simultaneously at 17 sites by citizen scientists (observational data set) and by professionals (specimen‐based data set). The sites differed with respect to the presence and age of hedgerows planted to improve habitat quality for pollinators. We found significant, positive correlations among the two data sets for higher level taxonomic composition, honey bee (Apis mellifera) abundance, non‐Apis bee abundance, bee richness, and bee community similarity. Results for both data sets also showed similar trends (or lack thereof) in these metrics among sites differing in the presence and age of hedgerows. Nevertheless, citizen scientists did not observe approximately half of the bee groups collected by professional scientists at the same sites. Thus, the utility of citizen‐science observational data may be restricted to detection of community‐level changes in abundance, richness, or similarity over space and time, and citizen‐science observations may not reliably reflect the abundance or frequency of occurrence of specific pollinator species or groups. 相似文献
8.
Although induced plant responses to herbivory are well studied as mechanisms of resistance, how induction shapes community interactions and ultimately plant fitness is still relatively unknown. Using a wild tomato, Solanum peruvianum, native to the Peruvian Andes, we evaluated the disruption of pollination as a potential ecological cost of induced responses. More specifically, we tested the hypothesis that metabolic changes in herbivore-attacked plants, such as the herbivore-induced emission of volatile organic compounds (VOCs), alter pollinator behavior and consequentially affect plant fitness. We conducted a series of manipulative field experiments to evaluate the role of herbivore-induced vegetative and floral VOC emissions as mechanisms by which herbivory affects pollinator behavior. In field surveys and bioassays in the plants' native habitat, we found that real and simulated herbivory (methyl jasmonate application) reduced attractiveness of S. peruvianum flowers to their native pollinators. We show that reduced pollinator preference, not resource limitation due to leaf tissue removal, resulted in reduced seed set. Solitary bee pollinators use floral plant volatiles, emitted in response to herbivory or methyl jasmonate treatment, as cues to avoid inflorescences on damaged plants. This herbivory-induced pollinator limitation can be viewed as a general cost of induced plant responses as well as a specific cost of herbivory-induced volatile emission. 相似文献
9.
Modeling the Persistence of Small Populations of Strongly Interdependent Species: Figs and Fig Wasps
Marie-Charlotte Anstett Martine Hossaert-McKey & Doyle McKey 《Conservation biology》1997,11(1):204-213
Conservation problems are usually studied at the population or ecosystem levels. Formulating predictive theory for the domain in between has been difficult. Fig trees and their pollinating wasps, principally tropical groups of organisms, form pairs of obligate mutualists that provide unique opportunities for studying the influence of species interactions on the survival of small populations. Survival of each partner depends on that of the associated species. The pollinator population can be maintained only if figs are produced year-round. Because fig trees flower synchronously at the individual level, wasps have to locate a new individual host tree at each generation. We describe results of simulation models estimating the minimum number of trees required to maintain a wasp population using two levels of the criteria: (1) different probability of survival (50% and 99%) and (2) different time of survival (5 or 1000 years). We also examined how these different estimates are sensitive to differences in the seasonality of flowering period and in the length of the period of female receptivity in figs. Such estimates can be used to understand the potential effects of the reduction of fig population size via fragmentation. Unlike most studies on the effect of low population size on population viability, our paper focuses on maintenance of a biotic interaction, rather than on single-species dynamics. The biotic interaction on which we focus is important because figs in many tropical ecosystems may be keystone resources for frugivores that are in turn essential seed dispersal agents for other plants. 相似文献
10.
Mimics and magnets: the importance of color and ecological facilitation in floral deception 总被引:1,自引:0,他引:1
Plants that lack floral rewards can attract pollinators if they share attractive floral signals with rewarding plants. These deceptive plants should benefit from flowering in close proximity to such rewarding plants, because pollinators are locally conditioned on floral signals of the rewarding plants (mimic effect) and because pollinators are more abundant close to rewarding plants (magnet effect). We tested these ideas using the non-rewarding South African plant Eulophia zeyheriana (Orchidaceae) as a study system. Field observations revealed that E. zeyheriana is pollinated solely by solitary bees belonging to a single species of Lipotriches (Halictidae) that appears to be closely associated with the flowers of Wahlenbergia cuspidata (Campanulaceae), a rewarding plant with which the orchid is often sympatric. The pale blue color of the flowers of E. zeyheriana differs strongly from flowers of its congeners, but is very similar to that of flowers of W. cuspidata. Analysis of spectral reflectance patterns using a bee vision model showed that bees are unlikely to be able to distinguish the two species in terms of flower color. A UV-absorbing sunscreen was applied to the flowers of the orchid in order to alter their color, and this resulted in a significant decline in pollinator visits, thus indicating the importance of flower color for attraction of Lipotriches bees. Pollination success in the orchid was strongly affected by proximity to patches of W. cuspidata. This was evident from one of two surveys of natural populations of the orchid, as well as experiments in which we translocated inflorescences of the orchid either into patches of W. cuspidata or 40 m outside such patches. Flower color and location of E. zeyheriana plants relative to rewarding magnet patches are therefore key components of the exploitation by this orchid of the relationship between W. cuspidata and Lipotriches bee pollinators. 相似文献
11.
Marissa L. Parrott Simon J. Ward Peter D. Temple-Smith 《Behavioral ecology and sociobiology》2007,61(7):1075-1079
Females show mate preferences for males that are genetically dissimilar to themselves in a variety of taxa, but how females
choose these males is not clearly understood. In this study, we examined the effects of olfactory stimuli and genetic relatedness
on female mate choice in a small carnivorous marsupial, the agile antechinus (Antechinus agilis), during two breeding seasons. Captive female antechinus in oestrus were provided with a combination of male urine and body
scent from two novel males, one more genetically similar and one more dissimilar to the females, in a Y-maze olfactometer.
Genetic relatedness between females and pairs of males was determined using highly polymorphic, species-specific, microsatellite
markers. Females consistently chose to visit the scents of males that were genetically dissimilar to themselves first, spent
significantly more time near the source of those scents and showed more sexual and non-exploratory behaviours near those scents.
These data demonstrate that chemosensory cues are important in mate choice in the agile antechinus and that females prefer
males that are genetically dissimilar to themselves. 相似文献
12.
Günther Raspotnig Miriam Schaider Edith Stabentheiner Hans-Jörg Leis Ivo Karaman 《Chemoecology》2014,24(2):43-55
While considerable knowledge on the chemistry of the scent gland secretions from the opilionid suborders Laniatores and Cyphophthalmi has been compiled, it is the Palpatores (Eupnoi and Dyspnoi) where chemical data are scarce. In particular, the Dyspnoi have remained nearly unstudied, mainly due to their reported general reluctance to release secretions as well as to the phenomenon of production of insoluble—and inaccessible—solid secretion. We here show that at least certain nemastomatid Dyspnoi, namely all three species of genus Carinostoma, indeed produce a volatile secretion, comprising octan-3-one, 6-methyl-5-hepten-2-one and acetophenone in species-specific combinations. In all Carinostoma spp., these volatiles are embedded in a semi-volatile, naphthoquinone matrix (mainly 1,4-naphthoquinone and 6-methyl-1,4-naphthoquinone). In detail, acetophenone and traces of naphthoquinones characterize the secretions of Carinostoma carinatum. A mixture of octan-3-one, 6-methyl-5-hepten-2-one and large amounts of naphthoquinones were found in C. elegans, and 6-methyl-5-hepten-2-one together with small amounts of naphthoquinones in the secretions of C. ornatum. So far, exclusively naphthoquinones had been reported from a single dyspnoan hitherto studied, Paranemastoma quadripunctatum. 相似文献
13.
Peter M. Kappeler 《Behavioral ecology and sociobiology》1998,42(6):411-421
The goals of this study were to investigate the transmission and possible functions of chemical signals in intragroup communication
among ring-tailed lemurs, Lemur catta. In particular, I examined the effects of sex on these processes because sexual selection theory predicts specific functions
for chemical signals. I recorded all interactions with 214 scent marks of 11 male and 9 female ring-tailed lemurs during the
first 10 min following their deposition. I found that 62% of these scent marks were investigated with a median latency of
30 s and that 89% of investigated scents were also counter-marked by the receiver. The type of focal scent mark (male or female
anogenital and male antebrachial mark) had a significant effect on both the timing and type of response. Males investigated
and counter-marked female scents more often than vice versa, but significant second-order transitions suggested that the behavior
of an animal was not only influenced by the immediately preceding scent mark and that a scent is not completely masked by
a counter-mark. There was no evidence for an audience effect, and only social rank of female senders had an effect on receivers.
Variation in the response of receivers across reproductive seasons as a function of senders' sex indicated that female scents
may function in mate attraction and competition among females, whereas male scents may be primarily used in intrasexual competition.
Three main conclusions emerged. First, the exchange of olfactory signals within groups was highly structured and surprisingly
efficient. Second, olfactory signals may constitute general mesasages whose transfer is partly controlled by the receiver.
Finally, sexual selection theory provides a useful theoretical framework for functional examinations of mammalian olfactory
communication.
Received: 13 June 1997 / Accepted after revision: 20 March 1998 相似文献
14.
Almost 200 species of orchid bees are the exclusive pollinators of nearly 700 specialized orchids in the neotropics. This well-known mutualism involves orchids, called perfume orchids, which produce species-specific blends of floral fragrances, and male orchid bees, which collect and use these fragrance compounds during their courtship. We report here the naturalization of an orchid bee, Euglossa viridissima, in southern Florida, USA, where perfume orchids are absent. Chemical analysis of the contents of the fragrance storage organs in the hind tibias of 59 male bees collected in Florida identified 55 fragrance compounds, including 27 known from the perfumes of nine species of E. viridissima's orchid mutualists in Mesoamerica. Aromatic leaves, such as basil, were found to be important surrogate sources of needed fragrance compounds in Florida. The bee's ability to live and become abundant in the absence of its orchid mutualists suggests that the orchid bee-perfume orchid mutualism may be facultative for the bees, even though it is obligatory for the orchids. This invasive bee visits and potentially pollinates the flowers of many plants in Florida, behavior that could promote the abundance of selected exotic and native species. 相似文献
15.
We investigated the ontogeny of responses to scent marks in immature terrestrial salamanders (Salamandra lanzai) that inhabit the southwest Alps. In this species, sexual maturity is usually reached at about 8 years, and adults exhibit territoriality. One should expect territoriality to take place largely before the acquisition of sexual maturity if sexual competition is not the main force driving territoriality. However, both the difficulties for inexperienced animals to find a suitable territory and size-related competition may delay the acquisition of territoriality in juveniles. We performed choice tests with juveniles belonging to two age groups (1±1 years old versus 4±1 years old). Each focal animal was offered, in random order, the choice between two shelters, one without scent and the other containing one of the following scents: own, same-aged animal, a juvenile belonging to the other age group, or adult female. We also performed choice tests with adult females for which the scents of two juveniles belonging to a different age group were successively offered in a random order. Older juveniles were strongly attracted toward their own shelter and mostly avoided the shelters that contained the scent of juveniles of about the same age and of adult females. Adult females avoided the scents of older juveniles but not younger juveniles. These results therefore suggest that older juveniles use territorial marking. Conversely, young juveniles behaved randomly with respect to their own scents and to those of a same-aged juvenile, and they were significantly attracted towards the odor of an older animal, especially adult females. Both older juveniles and adult females displayed a random behavior toward the scents of young juveniles. Our results suggest that young juveniles do not defend territories but use spaces occupied by older individuals.Communicated by A. Mathis 相似文献
16.
Though it is known that flower scent not only attracts pollinators but also herbivores, little is known about the importance
of flower scent on the distribution of leaf herbivores among individuals within a plant species. In this study we determined
the distribution of galls induced by the sawfly Pontania proxima (Serville 1823) (Hymenoptera, Tenthredinidae, Nematinae) on flowering and non-flowering representatives of several clones
belonging to Salix fragilis and S. × rubens (Salicaceae). Further, amounts and composition of scent of flowering and non-flowering twigs were compared (dynamic headspace-gas
chromatography–mass spectrometry, DHS-GC–MS), and a scent sample collected from flowering twigs of S. fragilis was tested by coupled gas chromatography and electroantennographic detection (GC-EAD) on the antennae of P. proxima females. The results show that the presence of flower catkins on plants led to a higher degree of allocation with galls,
but the number of galls differed not between flowering and non-flowering plants. The DHS-GC–MS analyses revealed that the
total amount of flower scent emitted per flowering twig is about 90 times higher than the scent emitted by a non-flowering
twig. Further, several compounds were emitted only by flowering but not by non-flowering twigs. In the GC-EAD analyses, antennae
consistently responded not only to green leaf volatiles, but also to compounds emitted only by the flowers (e.g. 1,4-dimethoxybenzene).
These flower scent compounds are suggested to affect the host plant choice by attracting more sawflies from the distance to
flowering plants compared to non-flowering plants. The EAD-active compounds emitted from vegetative plant parts are assumed
to act as long-distance signals especially when flowers are absent on host plants, e.g. during the oviposition period of the
second generation of P. proxima. 相似文献
17.
Frank J. Joyce 《Behavioral ecology and sociobiology》1993,32(2):71-77
Summary Rufous-naped wrens (Campylorhynchus rufinucha) in northwestern Costa Rica build breeding nests most frequently in ant-acacia trees (Acacia collinsii) and occasionally near wasp nests in ant-acacia trees. By moving occupied wasp nests (Polybia rejecta) to randomly chosen ant-acacia trees with wren nests, I tested the hypothesis that wrens nesting near wasp nests were more likely to fledge young than wrens not nesting near wasp nests. Wrens whose nests were near experimentally relocated wasp nests were significantly more likely to fledge young (37.5% of 16 attempts in 1987 and 75% of 12 attempts in 1988) than were wrens whose nests had no wasp nests placed near them (0% of 16 attempts in 1987 and 20% of 15 attempts in 1988). In 15 cases, repeated nesting attempts occurred in the same trees both with and without experimentally-placed wasp nests. Analysis of these data allowed a comparison of the effect of wasp nests on fledging success while differences among trees were controlled. Within the same tree, nesting attempts associated with wasp nests were significantly more likely to fledge young than nesting attempts without wasp nests. Predation was the primary cause of nest failure, and within forest, white-faced monkeys (Cebus capucinus) were the most important predators. The difference in success of wren nests with and without wasps and observations of predators indicate that enhancement of fledging success was due to deterrence of predatory vertebrates by wasps. 相似文献
18.
Nectar secondary compounds affect self-pollen transfer: implications for female and male reproduction 总被引:2,自引:0,他引:2
Pollen movement within and among plants affects inbreeding, plant fitness, and the spatial scale of genetic differentiation. Although a number of studies have assessed how plant and floral traits influence pollen movement via changes in pollinator behavior, few have explored how nectar chemical composition affects pollen transfer. As many as 55% of plants produce secondary compounds in their nectar, which is surprising given that nectar is typically thought to attract pollinators. We tested the hypothesis that nectar with secondary compounds may benefit plants by encouraging pollinators to leave plants after visiting only a few flowers, thus reducing self-pollen transfer. We used Gelsemium sempervirens, a plant whose nectar contains the alkaloid gelsemine, which has been shown to be a deterrent to foraging bee pollinators. We found that high nectar alkaloids reduced the total and proportion of self-pollen received by one-half and one-third, respectively. However, nectar alkaloids did not affect female reproduction when we removed the potential for self-pollination (by emasculating all flowers on plants). We then tested the assumption that self-pollen in combination with outcrossed pollen depresses seed set. We found that plants were weakly self-compatible, but self-pollen with outcrossed pollen did not reduce seed set relative to solely outcrossed flowers. Finally, an exponential model of pollen carryover suggests that high nectar alkaloids could benefit plants via increased pollen export (an estimate of male function), but only when pollinators were efficient and abundant and plants had large floral displays. Results suggest that high nectar alkaloids may benefit plants via increased pollen export under a restricted set of ecological conditions, but in general, the costs of high nectar alkaloids in reducing pollination balanced or outweighed the benefits of reducing self-pollen transfer for estimates of female and male reproduction. 相似文献
19.
Collapse of a pollination web in small conservation areas 总被引:6,自引:0,他引:6
A suspected global decline in pollinators has heightened interest in their ecological significance. In a worst-case scenario, the decline of generalist pollinators is predicted to trigger cascades of linked declines among the multiple specialist plant species to which they are linked, but this has not been documented. I studied a portion of a pollination web involving a generalist pollinator, the oil-collecting bee Rediviva peringueyi, and a community of oil-secreting plants. Across 27 established conservation areas located in the Cape Floral Region, I found substantial variation in the bees' occurrence in relation to soil type and the successional stage of the vegetation. Anthropogenic declines were detectable against this background of naturally occurring variation: R. peringueyi was absent from small conservation areas (< 385 ha) in an urban matrix. In the absence of the bee, seed set failed in six specialist plant species that are pollinated only by R. peringueyi but remained high in a pollination generalist, which had replacement pollinators. The findings are consistent with theoretical predictions of the importance of generalist pollinators in maintaining the structure of pollination webs. 相似文献
20.
Understanding how anthropogenic disturbances affect plant–pollinator systems has important implications for the conservation of biodiversity and ecosystem functioning. Previous laboratory studies show that pesticides and pathogens, which have been implicated in the rapid global decline of pollinators over recent years, can impair behavioral processes needed for pollinators to adaptively exploit floral resources and effectively transfer pollen among plants. However, the potential for these sublethal stressor effects on pollinator–plant interactions at the individual level to scale up into changes to the dynamics of wild plant and pollinator populations at the system level remains unclear. We developed an empirically parameterized agent-based model of a bumblebee pollination system called SimBee to test for effects of stressor-induced decreases in the memory capacity and information processing speed of individual foragers on bee abundance (scenario 1), plant diversity (scenario 2), and bee–plant system stability (scenario 3) over 20 virtual seasons. Modeling of a simple pollination network of a bumblebee and four co-flowering bee-pollinated plant species indicated that bee decline and plant species extinction events could occur when only 25% of the forager population showed cognitive impairment. Higher percentages of impairment caused 50% bee loss in just five virtual seasons and system-wide extinction events in less than 20 virtual seasons under some conditions. Plant species extinctions occurred regardless of bee population size, indicating that stressor-induced changes to pollinator behavior alone could drive species loss from plant communities. These findings indicate that sublethal stressor effects on pollinator behavioral mechanisms, although seemingly insignificant at the level of individuals, have the cumulative potential in principle to degrade plant–pollinator species interactions at the system level. Our work highlights the importance of an agent-based modeling approach for the identification and mitigation of anthropogenic impacts on plant–pollinator systems. 相似文献