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1.
Ann Bot ; 127(2): 231-239, 2021 01 07.
Artigo em Inglês | MEDLINE | ID: mdl-33410906

RESUMO

BACKGROUND AND AIMS: The great diversity of floral characteristics among animal-pollinated plants is commonly understood to be the result of coevolutionary interactions between plants and pollinators. Floral antagonists, such as nectar thieves, also have the potential to exert an influence upon the selection of floral characteristics, but adaptation against floral antagonists has attracted comparatively little attention. We found that the corollas of hornet-pollinated Codonopsis lanceolata (Campanulaceae) and the tepals of bee-pollinated Fritillaria koidzumiana (Liliaceae) are slippery to nectar-thieving ants living in the plant's habitat; because the flowers of both species have exposed nectaries, slippery perianths may function as a defence against nectar-thieving ants. METHODS: We conducted a behavioural experiment and observed perianth surface microstructure by scanning electron microscopy to investigate the mechanism of slipperiness. Field experiments were conducted to test whether slippery perianths prevent floral entry by ants, and whether ant presence inside flowers affects pollination. KEY RESULTS: Scanning electron microscopy observations indicated that the slippery surfaces were coated with epicuticular wax crystals. The perianths lost their slipperiness when wiped with hexane. Artificial bridging of the slippery surfaces using non-slippery materials allowed ants to enter flowers more frequently. Experimental introduction of live ants to the Codonopsis flowers evicted hornet pollinators and shortened the duration of pollinator visits. However, no statistical differences were found in the fruit or seed sets of flowers with and without ants. CONCLUSIONS: Slippery perianths, most probably based on epicuticular wax crystals, prevent floral entry by ants that negatively affect pollinator behaviour. Experimental evidence of floral defence based on slippery surfaces is rare, but such a mode of defence may be widespread amongst flowering plants.


Assuntos
Formigas , Magnoliopsida , Animais , Abelhas , Flores , Néctar de Plantas , Polinização
2.
Am J Bot ; 108(1): 37-50, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33449391

RESUMO

PREMISE: Floral rewards are essential in understanding floral function and evolution of the relationships between flowers and pollinators. Whether sugars are present in stigmatic exudates in Anthurium and whether it has floral nectaries have remained controversial because of the scarcity of structural studies. To solve these questions, we investigated the floral anatomy of A. andraeanum to elucidate whether (1) tepals are secretory organs, (2) tepals possess a structurally recognizable nectary, and (3) tepalar secretion differs from stigmatic secretion. METHODS: Floral structure was assessed through light and electron microscopy of samples of immature, pistillate, and staminate flowers. The dynamics of the starch reserve was investigated using histochemical tests, and the sugar content in the floral exudates was assessed using thin-layer chromatography. RESULTS: Sugar analysis did not detect sucrose, glucose, or fructose in stigmatic secretions, but confirmed their presence in tepalar secretions. Stigmatic secretion was produced by secretory stigmatic papillae; tepalar exudates were produced by nonvascularized nectaries in the apex of tepals. These nectaries were characterized by modified stomata and cells with cytoplasm rich in organelles, and a high content of calcium oxalate crystals. CONCLUSIONS: Our results showed for the first time nectaries on tepals and true nectar secretion for A. andraeanum. Stigmatic secretion appears to be a distinct substance, and its often-reported sugar content seems to be a result of sample contamination. Nectar and stigmatic secretions have been often mistaken in other Anthurium species and deserve a revision for this genus.


Assuntos
Flores , Néctar de Plantas , Secreções Corporais , Carboidratos , Organelas
3.
Ecotoxicol Environ Saf ; 207: 111268, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32916533

RESUMO

Foraging is essential for honey bee colony fitness and is enhanced by the waggle dance, a recruitment behavior in which bees can communicate food location and quality. We tested if the consumption of nectar (sucrose solution) with a field-realistic concentration of 4 ppm flupyradifurone (FPF) could alter foraging behavior and recruitment dancing in Apis mellifera. Foragers were repelled by FPF. They visited the FPF feeder less often and spent less time imbibing sucrose solution (2.5 M, 65% w/w) with FPF. As a result, bees feeding on the FPF treatment consumed 16% less nectar. However, FPF did not affect dancing: there were no effects on unloading wait time, the number of dance bouts per nest visit, or the number of dance circuits performed per dance bout. FPF could therefore deter bees from foraging on contaminated nectar. However, the willingness of bees to recruit nestmates for nectar with FPF is concerning. Recruitment can rapidly amplify the number of foragers and could overcome the decrease in consumption of FPF-contaminated nectar, resulting in a net inflow of pesticide to the colony. FPF also significantly altered the expression of 116 genes, some of which may be relevant for the olfactory learning deficits induced by FPF and the toxicity of FPF.


Assuntos
4-Butirolactona/análogos & derivados , Abelhas/fisiologia , Inseticidas/toxicidade , Néctar de Plantas , Piridinas/toxicidade , 4-Butirolactona/toxicidade , Animais , Abelhas/efeitos dos fármacos , Comportamento Alimentar , Alimentos , Sacarose
4.
PLoS One ; 15(12): e0242486, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33326432

RESUMO

Paper wasps (Polistes dominula), parasitized by the strepsipteran Xenos vesparum, are castrated and desert the colony to gather on plants where the parasite mates and releases primary larvae, thus completing its lifecycle. One of these plants is the trumpet creeper Campsis radicans: in a previous study the majority of all wasps collected from this plant were parasitized and focused their foraging activity on C. radicans buds. The unexpected prevalence and unusual feeding strategy prompted us to investigate the influence of this plant on wasp behavior and physiology through a multidisciplinary approach. First, in a series of laboratory bioassays, we observed that parasitized wasps spent more time than non-parasitized ones on fresh C. radicans buds, rich of extra-floral nectaries (EFNs), while the same wasps ignored treated buds that lacked nectar drops. Then, we described the structure and ultra-structure of EFNs secreting cells, compatible with the synthesis of phenolic compounds. Subsequently, we analysed extracts from different bud tissues by HPLC-DAD-MS and found that verbascoside was the most abundant bioactive molecule in those tissues rich in EFNs. Finally, we tested the immune-stimulant properties of verbascoside, as the biochemical nature of this compound indicates it might function as an antibacterial and antioxidant. We measured bacterial clearance in wasps, as a proxy for overall immune competence, and observed that it was enhanced after administration of verbascoside-even more so if the wasp was parasitized. We hypothesize that the parasite manipulates wasp behavior to preferentially feed on C. radicans EFNs, since the bioactive properties of verbascoside likely increase host survival and thus the parasite own fitness.


Assuntos
Antibacterianos/farmacologia , Glucosídeos/farmacologia , Holometábolos/fisiologia , Interações Hospedeiro-Parasita , Fenóis/farmacologia , Vespas/parasitologia , Animais , Antibacterianos/química , Antibacterianos/isolamento & purificação , Bignoniaceae/parasitologia , Cromatografia Líquida de Alta Pressão , Comportamento Alimentar/efeitos dos fármacos , Glucosídeos/química , Glucosídeos/isolamento & purificação , Imunidade Inata/efeitos dos fármacos , Imunocompetência , Larva/fisiologia , Masculino , Espectrometria de Massas/métodos , Fenóis/química , Fenóis/isolamento & purificação , Néctar de Plantas/química , Vespas/efeitos dos fármacos , Vespas/imunologia
5.
Sci Total Environ ; 749: 142305, 2020 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-33370885

RESUMO

Floral nectar harbors microbial communities which have significant impacts on its chemistry, volatiles, nutritional contents, and attractiveness for pollinators. Yet, fundamental knowledge regarding the structure and composition of nectar-associated microbiomes remains largely unknown. Especially elusive are the environmental factors and spatial effects that shape nectar-inhabiting microbial communities. The aim of this study was to explore and analyze the role of geographical and environmental factors affecting the composition and global distribution of floral nectar microbiota. We explored and compared the structure of bacterial communities inhabiting the floral nectar of the widely spread and invasive tobacco tree (Nicotiana glauca) in six continents: South and North America, Australia, Europe, Africa, and Asia, using 16S rRNA gene sequencing. Environmental abiotic data for each sampled plant was obtained from the Worldclim database and applied for inferring the effects of environmental conditions on bacterial community structure and diversity. Most abundant in the nectar were the Proteobacteria, Firmicutes, and Actinobacteria phyla, with Acinetobacter and Rosenbergiella (Proteobacteria) being the dominant bacterial genera that contributed most to the dissimilarities between sites. Acinetobacter and Rosenbergiella abundances were negatively correlated and significantly higher in the Mediterranean regions (Greece, Israel, and the Canary Islands) compared to Argentina and Australia. Temperature, site-elevation, rainfall, and density of vegetation were found to have significant effects on the structure and diversity of these bacterial communities in the nectar. Vegetation density was positively correlated with microbial diversity, while increased temperatures and elevation reduced the diversity and evenness of bacterial communities. Mantel's test showed that the similarity between the bacterial communities' composition significantly decreased as distances between them increased. We conclude that both geographical distance and local environmental abiotic conditions affect and shape the composition and diversity of nectar inhabiting bacterial communities.


Assuntos
Néctar de Plantas , África , Argentina , Ásia , Austrália , Europa (Continente) , Grécia , Israel , América do Norte , RNA Ribossômico 16S/genética , Espanha
6.
An Acad Bras Cienc ; 92(suppl 2): e20181172, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33053068

RESUMO

To study the ontogeny of the extrafloral nectaries present in the inflorescences of Vigna luteola (Jacq.) Benth (Leguminosae, Phaseolinae), the location, morphology, anatomy of the earliest stages, histology of the definitive structures and ultrastructure of the secretory stage were analyzed. The extrafloral nectaries at different developmental stages were examined with light microscopy and scanning electron microscopy. The secretory stage was also examined with transmission electron microscopy. The racemose inflorescence of V. luteola has six nodes. At each node, a short globose secondary axis bears two flowers and one to three extrafloral nectaries. Each extrafloral nectary originates from the abscission of a flower bud and is formed by two differentiated zones: a ring of epidermal cells surrounding a group of longitudinally enlarged papillose central cells, both with underlying secretory parenchyma. The primary secretory tissue consists of the central cells, while the ring contributes to secretion to a lesser degree. Secretion is granulocrine, by means of exocytotic vesicles and plasmalemma invaginations. Four developmental stages succeed; the third one being the secretory. The extrafloral nectaries activity period starts when the flowers of the same secondary axis open and ceases before fruit development.


Assuntos
Fabaceae , Vigna , Diferenciação Celular , Flores , Néctar de Plantas
7.
PLoS One ; 15(9): e0237561, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32877468

RESUMO

In increasingly urban landscapes, the loss of native pollen and nectar floral resources is impacting ecologically important pollinators. Increased urbanization has also brought about the rise of urban gardens which introduce new floral resources that may help replace those the pollinators have lost. Recently, studies have shown that the microbial communities of nectar may play an important role in plant-pollinator interactions, but these microbial communities and the floral visitors in urban environments are poorly studied. In this study we characterized the floral visitors and nectar microbial communities of Ascelpias curassavica, a non-native tropical milkweed commonly, in an urban environment. We found that the majority of the floral visitors to A. curassavica were honey bees followed closely by monarch butterflies. We also found that there were several unique visitors to each site, such as ants, wasps, solitary bees, several species of butterflies and moths, Anna's hummingbird, and the tarantula hawk wasp. Significant differences in the nectar bacterial alpha and beta diversity were found across the urban sites, although we found no significant differences among the fungal communities. We found that the differences in the bacterial communities were more likely due to the environment and floral visitors rather than physiological differences in the plants growing at the gardens. Greater understanding of the impact of urbanization on the nectar microbiome of urban floral resources and consequently their effect on plant-pollinator relationships will help to predict how these relationships will change with urbanization, and how negative impacts can be mitigated through better management of the floral composition in urban gardens.


Assuntos
Asclepias/microbiologia , Microbiota , Néctar de Plantas , Clima Tropical , Urbanização , Bactérias/crescimento & desenvolvimento , Biodiversidade , Flores/microbiologia , Fungos/crescimento & desenvolvimento
8.
Oecologia ; 193(4): 913-924, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32772157

RESUMO

In semi-arid environments, the marked contrast in temperature and precipitation over the year strongly shapes ecological communities. The composition of species and their ecological interactions within a community may vary greatly over time. Although intra-annual variations are often studied, empirical information on how plant-bird relationships are structured within and among years, and how their drivers may change over time are still limited. In this study, we analyzed the temporal dynamics of the structure of plant-hummingbird interaction networks by evaluating changes in species richness, diversity of interactions, modularity, network specialization, nestedness, and ß-diversity of interactions throughout four years in a Mexican xeric shrubland landscape. We also evaluated if the relative importance of abundance, phenology, morphology, and nectar sugar content consistently explains the frequency of pairwise interactions between plants and hummingbirds across different years. We found that species richness, diversity of interactions, nestedness, and network specialization did vary within and among years. We also observed that the ß-diversity of interactions was high among years and was mostly associated with species turnover (i.e., changes in species composition), with a minor contribution of interaction rewiring (i.e., shifting partner species at different times). Finally, the temporal co-occurrence of hummingbird and plant species among months was the best predictor of the frequency of pairwise interactions, and this pattern was consistent within and among years. Our study underscores the importance of considering the temporal scale to understand how changes in species phenologies, and the resulting temporal co-occurrences influence the structure of interaction networks.


Assuntos
Aves , Polinização , Animais , México , Néctar de Plantas , Plantas
9.
Biol Lett ; 16(8): 20200449, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32780979

RESUMO

Nectarivorous insects generally adopt suction or lapping to extract nectar from flowers and it is believed that each species exhibits one specific feeding pattern. In recent literature, large groups of nectarivores are classified as either 'suction feeders', imbibing nectar through their proboscis, or 'lappers', using viscous dipping. Honeybees (Apis mellifera) are the well-known lappers by virtue of their hairy tongues. Surprisingly, we found that honeybees also employ active suction when feeding on nectar with low viscosity, defying their classification as lappers. Further experiments showed that suction yielded higher uptake rates when ingesting low-concentration nectar, while lapping resulted in faster uptake when ingesting nectar with higher sugar content. We found that the optimal concentration of suction mode in honeybees coincided with the one calculated for other typical suction feeders. Moreover, we found behavioural flexibility in the drinking mode: a bee is able to switch between lapping and suction when offered different nectar concentrations. Such volitional switching in bees can enhance their feeding capabilities, allowing them to efficiently exploit the variety of concentrations presented in floral nectars, enhancing their adaptability to a wide range of energy sources.


Assuntos
Comportamento Alimentar , Néctar de Plantas , Animais , Abelhas , Transporte Biológico , Flores , Viscosidade
10.
Proc Natl Acad Sci U S A ; 117(36): 22552-22560, 2020 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-32848061

RESUMO

The evolution of novel features, such as eyes or wings, that allow organisms to exploit their environment in new ways can lead to increased diversification rates. Therefore, understanding the genetic and developmental mechanisms involved in the origin of these key innovations has long been of interest to evolutionary biologists. In flowering plants, floral nectar spurs are a prime example of a key innovation, with the independent evolution of spurs associated with increased diversification rates in multiple angiosperm lineages due to their ability to promote reproductive isolation via pollinator specialization. As none of the traditional plant model taxa have nectar spurs, little is known about the genetic and developmental basis of this trait. Nectar spurs are a defining feature of the columbine genus Aquilegia (Ranunculaceae), a lineage that has experienced a relatively recent and rapid radiation. We use a combination of genetic mapping, gene expression analyses, and functional assays to identify a gene crucial for nectar spur development, POPOVICH (POP), which encodes a C2H2 zinc-finger transcription factor. POP plays a central role in regulating cell proliferation in the Aquilegia petal during the early phase (phase I) of spur development and also appears to be necessary for the subsequent development of nectaries. The identification of POP opens up numerous avenues for continued scientific exploration, including further elucidating of the genetic pathway of which it is a part, determining its role in the initial evolution of the Aquilegia nectar spur, and examining its potential role in the subsequent evolution of diverse spur morphologies across the genus.


Assuntos
Aquilegia/fisiologia , Néctar de Plantas/metabolismo , Proteínas de Plantas , Fatores de Transcrição , Dedos de Zinco/genética , Aquilegia/genética , Flores/genética , Flores/metabolismo , Néctar de Plantas/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
11.
Proc Biol Sci ; 287(1933): 20201615, 2020 08 26.
Artigo em Inglês | MEDLINE | ID: mdl-32842923

RESUMO

An adequate supply of macro- and micronutrients determines health and reproductive success in most animals. Many bee species, for example, collect nectar and pollen to satisfy their demands for carbohydrates, protein and fat, respectively. Bees can assess the quality of pollen by feeding on it, but also pre-digestively by means of chemotactile assessment. Whether they additionally use larval nutritional experience, as has been shown for Drosophila melanogaster and Bombyx mori, is unknown. In this study, we tested whether pollen selection of bumblebee foragers is affected by nutritional experience (acquired before the onset of foraging) or solely by food quality. Bumblebee larvae were fed with one out of three different pollen blends. As adults, they were offered all three blends when they started foraging for the first time. We found all treatment groups to prefer one out of the three blends. This blend provided the highest nutritional quality and increased the bees' lifespan, as shown by feeding studies with microcolonies. Besides, bees also chose the pollen blend fed during their larval stage more often than expected, indicating a significant effect of pre-foraging experience on adult pollen foraging behaviour. The combination of both direct pollen quality assessment and pre-foraging experience (i.e. during the larval phase or as early imagines) seems to allow foraging bumblebees to efficiently select the most suitable pollen for their colony.


Assuntos
Abelhas/fisiologia , Sinais (Psicologia) , Comportamento Alimentar , Pólen , Animais , Drosophila melanogaster , Larva , Néctar de Plantas , Polinização , Reprodução
12.
Oecologia ; 193(3): 619-630, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32671460

RESUMO

While morphological differences such as tongue length are often featured as drivers of pollinator floral preferences, differences in chemical detection and tolerance to secondary compounds may also play a role. We sought to better understand the role of secondary compounds in floral preference by examining visitation of milkweed flowers, which can contain toxic cardenolides in their nectar, by bumble bees (Bombus spp.), some of their most abundant and important pollinators. We examine bumble bee species visitation of common milkweed (Asclepias syriaca) compared to other flowers in the field and test whether observed preferences may be influenced by avoidance and tolerance of cardenolides, as measured by the cardenolide ouabain, in the lab. We reveal that common milkweed is visited predominantly by one bumble bee species, Bombus griseocollis, in a ratio much higher than the abundance of this species in the community. We confirmed the presence and toxicity of cardenolides in A. syriaca nectar. Lab experiments revealed that B. griseocollis, compared to the common bumble bees B. impatiens and B. bimaculatus, exhibit greater avoidance of cardenolides, but only at levels that start to induce illness, whereas the other species exhibit either no or reduced avoidance of cardenolides, resulting in illness and mortality in these bees. Toxicity experiments reveal that B. griseocollis also has a substantially higher tolerance for cardenolides than B. impatiens. Together, these results support a potential evolutionary association between B. griseocollis and milkweed that may involve increased ability to both detect and tolerate milkweed cardenolides.


Assuntos
Asclepias , Néctar de Plantas , Animais , Abelhas , Flores , Polinização
13.
Ann Bot ; 126(7): 1155-1164, 2020 11 24.
Artigo em Inglês | MEDLINE | ID: mdl-32674148

RESUMO

BACKGROUND AND AIMS: The temporal dimensions of floral adaptation to pollinators are not yet well understood, partly because we lack accurate information on the diel rhythms of flower visitation for many pollinators. We investigated whether diel patterns of pollinator visitation to flowers of the African woodland orchid Bonatea polypodantha are synchronized with rhythms of floral anthesis, scent emission and nectar availability. METHODS: Direct observations and motion-activated cameras were used to identify pollinators of B. polypodantha and to document their activity periods. The timing of pollinaria removal from flowers, emission of scent and availability of nectar was also measured. RESULTS: We found that B. polypodantha is pollinated exclusively by short-tongued hawkmoths. Pollinaria of the orchid are affixed between the labial palps of the moths and brush over the protruding stigmatic arms. The flowers also receive visits by long-tongued hawkmoths, but these act as nectar thieves. Tracking of pollinaria removal from flowers confirmed that pollination occurs only at night. Camera footage revealed a striking crepuscular pattern of foraging by short-tongued hawkmoths with peaks of activity during the twilight periods at dusk and at dawn. In contrast, long-tongued hawkmoths were found to visit flowers throughout the night. Flowers of B. polypodantha exhibit unimodal peaks of anthesis, scent emission (dominated by nitrogenous aromatics) and nectar availability before or around dusk. CONCLUSIONS: Flowers of B. polypodantha are pollinated exclusively by short-tongued hawkmoths, which show crepuscular foraging activity at dusk and dawn. Floral phenophases of the orchid are closely synchronized with the peak of pollinator activity at dusk.


Assuntos
Mariposas , Orchidaceae , Animais , Flores , Odorantes , Néctar de Plantas , Polinização
14.
Oecologia ; 194(3): 321-332, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32676820

RESUMO

Herbivores decrease plant fitness by consuming reproductive tissues, limiting resources, and/or affecting mutualisms. Although these mechanisms were extensively tested in chewing herbivores, the impact of other functional groups (e.g., sap-feeders) remains poorly understood. We investigated whether aphids affect plant reproduction via direct resource limitation on seed production and/or pollination interference. We compared plant traits and the seed set of naturally aphid-free vs. aphid-infested plants and then manipulated aphid presence and pollen receipt. We used path models to examine the links between variables. Nectar volume and seed set of aphid-infested plants was 54% and 42% lower than that of aphid-free plants. 72 h after removing aphids, nectar volume was restored to the level of aphid-free plants. When pollinators were excluded, the seed set of aphid-infested and aphid-free plants did not differ, suggesting that direct resource limitation on seed production was not the cause of reduced plant fitness. Manual addition of pollen restored the seed set of aphid-infested plants to the level of aphid-free plants, evidencing that plants were pollen limited. The path analysis showed a negative link between aphids and the seed set via nectar volume, supporting that nectar shortage caused by aphids may interfere with pollination and reduce plant fitness. Since aphids are crop pests and feed on a large number of animal-pollinated plants, the potential of these insects to influence pollination and plant fitness is high. This study emphasizes the ecological importance of aphids and the need to better understand the links between sap-feeding herbivory, pollination, and plant fitness.


Assuntos
Afídeos , Polinização , Animais , Herbivoria , Néctar de Plantas , Pólen
15.
PLoS One ; 15(6): e0226469, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32525873

RESUMO

Colour is an important signal that flowering plants use to attract insect pollinators like bees. Previous research in Germany has shown that nectar volume is higher for flower colours that are innately preferred by European bees, suggesting an important link between colour signals, bee preferences and floral rewards. In Australia, flower colour signals have evolved in parallel to the Northern hemisphere to enable easy discrimination and detection by the phylogenetically ancient trichromatic visual system of bees, and native Australian bees also possess similar innate colour preferences to European bees. We measured 59 spectral signatures from flowers present at two preserved native habitats in South Eastern Australia and tested whether there were any significant differences in the frequency of flowers presenting higher nectar rewards depending upon the colour category of the flower signals, as perceived by bees. We also tested if there was a significant correlation between chromatic contrast and the frequency of flowers presenting higher nectar rewards. For the entire sample, and for subsets excluding species in the Asteraceae and Orchidaceae, we found no significant difference among colour categories in the frequency of high nectar reward. This suggests that whilst such relationships between flower colour signals and nectar volume rewards have been observed at a field site in Germany, the effect is likely to be specific at a community level rather than a broad general principle that has resulted in the common signalling of bee flower colours around the world.


Assuntos
Abelhas/fisiologia , Flores/metabolismo , Pigmentação , Néctar de Plantas/metabolismo , Polinização , Animais , Comportamento Animal , Açúcares/metabolismo
16.
Am J Bot ; 107(7): 957-969, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32592166

RESUMO

PREMISE: Opportunistic nectar-feeders may act as effective pollinators; nonetheless, we still lack information on whether these opportunistic species differ in their pollination effectiveness from specialized nectarivorous vertebrates and insects. Many nectar specialists have coevolved with the plants on which they feed; therefore, we would expect higher pollination effectiveness in specialists than in opportunistic feeders. Here, we assessed quantity and quality components of pollination effectiveness in specialist and opportunistic vertebrate nectarivores and insects, focusing on three plants from the Seychelles: Thespesia populnea, Polyscias crassa, and Syzygium wrightii. METHODS: We determined the quantity component (QNC) of pollination effectiveness with pollinator observations, and the quality component (QLC) by measuring fruit and seed set resulting from single visits by each pollinator. To detect potential negative effects of invasive ants on native plant-pollinator interactions, we classified pollinator visits (quantity component) as disturbed (>6 ants/30 min) vs. undisturbed. RESULTS: All focal plants were visited by insects, and vertebrate specialist and opportunist nectarivores, yet their pollination effectiveness differed. Flying insects were the most effective pollinators of T. populnea. The other two plants were most effectively pollinated by vertebrates; i.e., sunbirds (nectar specialists) in S. wrightii and Phelsuma geckos (nectar opportunists) in P. crassa, despite marked variation in QNC and QLC. Ant presence was associated with lower pollinator visitation rate in P. crassa and S. wrightii. CONCLUSIONS: Our study highlights the importance of all pollinator guilds, including opportunist nectarivorous vertebrates as pollinators of island plants, and the vulnerability of such interactions to disruption by nonnative species.


Assuntos
Formigas , Polinização , Animais , Flores , Espécies Introduzidas , Ilhas , Néctar de Plantas , Seicheles , Especialização
17.
Ecol Lett ; 23(10): 1550-1552, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32578283

RESUMO

A recent claim that evening primrose flowers adaptively secrete nectar in response to vibrations from hovering bees lacks supporting evidence. The authors fail to demonstrate that bees can access the concealed nectar and that their visits enhance plant fitness. Reanalysis of the authors' data raises additional concerns about their conclusions.


Assuntos
Néctar de Plantas , Polinização , Acústica , Animais , Abelhas , Flores , Atividade Motora
18.
Ecol Lett ; 23(9): 1421-1422, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32578293

RESUMO

Under noiseless experimental conditions, sugar concentration of secreted floral nectar may increase after flower exposure to nearby sounds of pollinator flight (Veits et al. 2019). However, we reject the argument that this represents adaptive plant behaviour, and consider that the appealing analogy between a flower and human ear is unjustified.


Assuntos
Néctar de Plantas , Polinização , Flores , Plantas , Som
19.
Ecol Lett ; 23(9): 1423-1425, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32578320

RESUMO

Ecol. Lett. 22, 2019, 1483 demonstrated, for the first time, a rapid response of a plant to the airborne sounds of pollinators. Pyke et al. argue that this response is unlikely to be adaptive. Here we clarify some misunderstandings, and demonstrate the potential adaptive value using theoretical modelling and field observations.


Assuntos
Néctar de Plantas , Polinização , Flores , Plantas , Som
20.
Ecol Lett ; 23(10): 1553-1554, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32578343

RESUMO

In Veits et al., we showed that flowers respond to a range of pollinator sounds by increased nectar sugar concentration. Here we clarify that (1) our argument is relevant to most pollinators, and not limited to bees (2) specifically, bees do access Oenothera Drumondii nectar in this area.


Assuntos
Néctar de Plantas , Polinização , Animais , Abelhas , Flores , Plantas , Açúcares
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