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Nectar
Kinds of Nectar Terms modified by Nectar Selected AbstractsEcology of yeasts in plant,bumblebee mutualism in Central EuropeFEMS MICROBIOLOGY ECOLOGY, Issue 2 2004Michael Brysch-Herzberg Abstract Yeast community involved in plant,bumblebee mutualism was investigated in three successive years. Yeasts were isolated from floral nectar, bumblebee queens after hibernation, bumblebee workers, and the honey provisions in nests. From the distribution of yeast species in the various microhabitats in the course of the year their ecology was assessed. Nectar of numerous plant species belonging to various plant families was analyzed in order to uncover possible impacts on the yeasts present in the nectar. Only ascomycetous yeasts were autochthonous members of the communities in the plant,bumblebee mutualism. Species in the Metschnikowia clade, the Starmarella clade, and the genera Debaryomyces and Zygosaccharomyces were associated with the mutualism. Some species appeared highly specialized, whereas others had a broader distribution. While physical and chemical properties of nectar had only limited influence on the abundance of nectar yeasts, the attractiveness of plants to the flower-visiting insects appears to have had a greater impact on the abundance and frequency of yeasts in the nectar of different plant species. [source] Nectar ,theft' by hummingbird flower mites and its consequences for seed set in Moussonia deppeanaFUNCTIONAL ECOLOGY, Issue 1 2001Lara C. Summary 1,Mites (Acari: Mesostigmata: Ascidae) that live and feed in the flowers of about 100 plant species are transported in the nares of hummingbirds (Trochilidae). Mites may compete with hummingbirds for nectar secreted by the host plants, and this could affect the dynamics and reproductive outcomes of the mutualism between plants and their pollinating hummingbirds. 2,Here we combined field observations and experimental manipulations to assess the role of hummingbird flower mites (Tropicoseius sp. nov.) on nectar secretion and reproductive output of protandrous Moussonia deppeana (Schlecht. & Cham.) Hanst. (Gesneriaceae) during their flowering period in a cloud forest remnant. 3,During the 4 days that the flowers of M. deppeana last, flowers were visited exclusively by hummingbirds (Lampornis amethystinus). Bud production per inflorescence peaked in December. There were few open flowers per inflorescence in November, but numbers increased as the flowering season progressed (December and January). 4,The availability of each flower phase differed over the flowering season. Staminate-phase flowers were more abundant over the flowering season than pistillate-phase flowers. These differences were statistically significant over time. 5,Nectar availability was reduced by up to 50% in the presence of hummingbird flower mites. Over the 4 days of observation, significantly more nectar was secreted to flowers from which mites were excluded than to flowers with no mite exclusion. The same effect was observed during flowering, but mites consumed a greater percentage of the total nectar secreted in December. 6,Significantly more nectar was secreted during the staminate phase than in the pistillate phase, independent of time and treatment. 7,A manual pollination experiment suggested that mites act like secondary pollinators in this self-compatible, non-autogamous plant, at least in flowers that were not pollinated manually and had no access to pollinating hummingbirds. 8,Although seed production was not reduced significantly by flower mites, our results suggest that the presence of floral mites can affect pollen transmission, as the amount of nectar available to hummingbirds was reduced drastically. This can directly affect hummingbird foraging patterns and reduce the fitness of the host plants. [source] Anthocyanin Degradation of Blueberry,Aronia Nectar in Glass Compared with Carton during StorageJOURNAL OF FOOD SCIENCE, Issue 8 2008K. Tro ABSTRACT:, Blueberry,aronia nectar is known as a rich source of anthocyanins, which are mostly destroyed during commercial storage of the product. The factors influencing the rate of degradation are connected to the oxygen protection offered by the packaging, as well as the type of anthocyanidin and the amount of glycosylated sugar. The current study was aimed to compare the stability of total anthocyanin between glass and carton packaging as well as to determine the stability of individual anthocyanin with respect to aglycone and glycosylated sugar. The degradation rate of total anthocyanin degradation rate was 22% higher in carton packaging than glass bottle. The ranking order of the stability of individual anthocyanin with respect to aglycone was as follows (from the most to least stable): cyanindin > peonidin > petunidin > malvidin = delphinidin. The ranking order of the stability of anthocyanins with respect to glycosylated sugars was as follows (from the most to least stable): glucose > galactose > arabinose. As individual anthocyanins have different degradation rates this study can be used to determine the most stable natural colorant and the most sensitive antioxidant among the anthocyanins tested. [source] Nectar and Pollen Sources for Honeybee (Apis cerana cerana Fabr.) in Qinglan Mangrove Area, Hainan Island, ChinaJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 11 2006Yi-Feng Yao Abstract In the present study, nectar and pollen sources for honeybee (Apis cerana cerana Fabr.) were studied in Qinglan mangrove area, Hainan Island, China, based on microscopic analysis of honey and pollen load (corbicular and gut contents) from honeybees collected in October and November 2004. Qualitative and quantitative melittopalynological analysis of the natural honey sample showed that the honey is of unifloral type with Mimosa pudica L. (Mimosaceae) as the predominant (89.14%) source of nectar and pollen for A. cerana cerana in October. Members of Araceae are an important minor (3%-15%) pollen type, whereas those of Arecaceae are a minor (<3%) pollen type. Pollen grains of Nypa fruticans Wurmb., Rhizophora spp., Excoecaria agallocha L., Lumnitzera spp., Bruguiera spp., Kandelia candel Druce, and Ceriops tagal (Perr.) C. B. Rob. are among the notable mangrove taxa growing in Qinglan mangrove area recorded as minor taxa in the honey. The absolute pollen count (i.e. the number of pollen grains/10 g honey sample) suggests that the honey belongs to Group V (>1 000 000). Pollen analysis from the corbicular and gut contents of A. cerana cerana revealed the highest representation (95.60%) of members of Sonneratia spp. (Sonneratiaceae), followed by Bruguiera spp. (Rhizophoraceae), Euphorbiaceae, Poaceae, Fabaceae, Arecaceae, Araceae, Anacardiaceae, and Rubiaceae. Of these plants, those belonging to Sonneratia plants are the most important nectar and pollen sources for A. cerana cerana and are frequently foraged and pollinated by these bees in November. (Managing editor: Ya-Qin Han) [source] Pollination biology of the sclerophyllous shrub Pultenaea villosa Willd. (Fabaceae) in southeast Queensland, AustraliaPLANT SPECIES BIOLOGY, Issue 1 2009JANE E. OGILVIE Abstract The pollination biology of the common shrub Pultenaea villosa Willd. was examined in a subtropical dry sclerophyll forest in eastern Australia. We determined floral phenology and morphology, the timing of stigma receptivity and anther dehiscence, nectar availability, the plant breeding system, and flower visitors. The shrub's flowers are typical zygomorphic pea flowers with hidden floral rewards and reproductive structures. These flowers require special manipulation for insect access. A range of insects visited the flowers, although bees are predicted to be the principle pollinators based on their frequency on the flowers and their exclusive ability to operate the wing and keel petals to access the reproductive structures. Nectar and pollen are offered as rewards and were actively collected by bees. Nectar is offered to visitors in minute amounts at the base of the corolla. In Toohey Forest, P. villosa flowers in spring and is the most abundant floral resource in the understory of the forest at this time. The breeding system experiment revealed that P. villosa requires outcrossing for high levels of seed set and that the overlap of stigma receptivity and pollen dehiscence within the flower suggests the potential for self-incompatibility. [source] Bird Pollination of Explosive Flowers While Foraging for Nectar and Caterpillars,BIOTROPICA, Issue 5 2006Kayna Agostini ABSTRACT Mucuna (Fabaceae) has explosive flowers that open only if a pressure is applied on their wings and keel. The cacique Cacicus haemorrhous inserts its bill into a flower and spreading its mandibles apart it opens the flower to take nectar. This icterine bird also preys upon caterpillars of the butterfly Astraptes talus that pupates within the flowers. Foraging with use of bill movements to take nectar or insects within a flower is an adequate mechanism to open and pollinate explosive flowers. We suggest that a plausible behavioral scenario for the pollination relationship between icterines and Mucuna -like flowers might start with the birds' searching for insects within flowers. RESUMEN El género Mucuna (Fabaceae) tiene flores explosivas que abren cuando se aplica una presión sobre sus alas o quillas. El boyero cacique, Cacicus haemorrhous, introduce su pico dentro de la flor y expande sus mandibulas abriendo la flor para beber el néctar. Esta ave Icterinae también depreda larvas de la mariposa Astraptes talus, la cual empupa dentro de las flores. El forrajeo con uso de movimientos del pico, para consumir el néctar o de insectos dentro de una flor, es un mecanismo adecuado para abrir y polinizar las flores explosivas. Sugerimos que este es un escenario comportamental razonable para la relación de la polinización entre especies de Icterinae y flores del tipo Mucuna, que podría iniciar con la búsqueda de las aves por insectos dentro de las flores. [source] Sugar Preferences in Nectar- and Fruit-Eating Birds: Behavioral Patterns and Physiological Causes,BIOTROPICA, Issue 1 2006Chris N. Lotz ABSTRACT Sucrose, glucose, and fructose are the three sugars that commonly occur in floral nectar and fruit pulp. The relative proportions of these three sugars in nectar and fruit in relation to the sugar preferences of pollinators and seed dispersers have received considerable attention. Based on the research of Herbert and Irene Baker and their collaborators, a dichotomy between sucrose-dominant hummingbird-pollinated flowers and hexose-dominant passerine flowers and fruits was proposed. Data on sugar preferences of several hummingbird species (which prefer sucrose) vs. a smaller sample of passerines (which prefer hexoses) neatly fitted this apparent dichotomy. This hummingbird,passerine dichotomy was strongly emphasized until the discovery of South African plants with sucrose-dominant nectars, which are pollinated by passerines that are able to digest, and prefer sucrose. Now we know that, with the exception of two clades, most passerines are able to assimilate sucrose. Most sugar preference studies have been conducted using a single, relatively high, sugar concentration in the nectar (ca 20%). Thus, we lack information about the role that sugar concentration might play in sugar selection. Because many digestive traits are strongly affected not only by sugar composition, but also by sugar concentration, we suggest that preferences for different sugar compositions are concentration-dependent. Indeed, recent studies on several unrelated nectar-feeding birds have found a distinct switch from hexose preference at low concentrations to sucrose preference at higher concentrations. Finally, we present some hypotheses about the role that birds could have played in molding the sugar composition of plant rewards. RESUMEN Sacarosa, glucosa y fructosa son los azúcares mas comunes en néctar floral y pulpa de fruta. La proporción relativa de estos azúcares en néctar floral y la pulpa de fruta han sido estudiadas en relación a las preferencias de azúcar de polinizadores y dispersores de semillas. Basandose en estudios de Herbert e Irene Baker y colaboradores se propuso la existencia de una dicotomía entre plantas con néctares ricos en sacarosa que son polinizadas por colibríes, y plantas con néctares y frutos ricos en hexosas que son polinizadas por paserinos. Datos sobre la preferencia de azúcares en varias especies de colibríes (que prefieren sacarosas) comparados con una pequeña muestra de paserinos (que prefieren hexosas) apoyan la existencia de la dicotomía propuesta. La dicotomía colibrí-paserino fue enfatizada por más de una década, hasta el descubrimiento de plantas sudafricanas con néctares ricos en sacarosa que son polinizadas por paserinos que prefieren sacarosa. Hoy sabemos que la mayoría de los paserinos, salvo los miembros de dos clados, pueden asimilar la sacarosa. La mayoría de los estudios sobre preferencias de azúcares han sido conducidos usando una sola concentración de azúcares en el néctar (ca 20%). Por lo tanto, carecemos de información sobre el papel que juega la concentración de azúcares en las preferencias de estos por las aves. Debido a que muchos procesos digestivos son afectados, no solo por la composición de azúcares, sino también por su concentración, sugerimos que las preferencias por diferentes azúcares dependerán de su concentración. Efectivamente, estudios recientes indican que diferentes aves prefieren alimentarse de hexosas a bajas concentraciones, y de sacarosa a altas concentraciones. Finalmente, presentamos algunas hipótesis sobre el papel que las aves pudieron haber tenido en la evolución de la composición de azúcares del néctar y la fruta que consumen. [source] Tropical Bees (Trigona hockingsi) Show No Preference for Nectar with Amino AcidsBIOTROPICA, Issue 1 2003Mark C. Gardener ABSTRACT We offered Australian tropical stingless bees (Trigona hockingsi) artificial nectar (30% sucrose w/v) either with or without added amino acids (3.30 mM). Bees showed no preference for nectar type, suggesting that sugars, rather than amino acids, play a greater role in nectar choice by this species. [source] Nectaries and reproductive biology of Croton sarcopetalus (Euphorbiaceae)BOTANICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 3 2001LEANDRO FREITAS Flower morphology, nectary structure, nectar chemical composition, breeding system, floral visitors and pollination were analysed in Croton sarcopetalus, a diclinous-monoecious shrub from Argentina. Male flowers have five receptacular nectaries, with no special vascular bundles, that consist of a uniserial epidermis with stomata subtended by a secretory parenchyma. Female flowers bear two different types of nectaries: inner (IN) and outer (ON) floral nectaries. IN, five in all, are structurally similar to the nectaries of male flowers. The five ON are vascularized, stalked, and composed of secretory, column-shaped epidermal cells without stomata subtended by secretory and ground parenchyma. In addition, ON act as post-floral nectaries secreting nectar during fruit ripening. Extrafloral nectaries (EFN) are located on petioles, stipules and leaf margins. Petiolar EFN are patelliform, stalked and anatomically similar to the ON of the female flower. Nectar sampled from all nectary types is hexose dominant, except for the ON of the female flower at the post-floral stage that is sucrose dominant. The species is self-compatible, but geitonogamous fertilization is rarely possible because male and female flowers are not usually open at the same time in the same individual, i.e. there is temporal dioecism. Flowers are visited by 22 insect species, wasps being the most important group of pollinators. No significant differences were found in fruit and seed set between natural and hand pollinated flowers. This pattern indicates that fruit production in this species is not pollen/pollinator limited and is mediated by a wide array of pollinators. [source] From the Linden Flower to Linden Honey , Volatile Constituents of Linden Nectar, the Extract of Bee-Stomach and Ripe HoneyCHEMISTRY & BIODIVERSITY, Issue 12 2004Regula Naef Honey is produced by honeybees (Apis mellifera), which collect nectar from flowers, digest it in their bodies, and deposit it in honeycombs, where it develops into ripe honey. We studied the evolution of the volatile constituents from the nectar of linden blossoms (Tilia cordata) to honey via the ,intermediate' honeybee. The sampling of the contents of the honey stomach or honey sack of the bee is unique. Extracts were prepared from nectar, from the liquid of the honey stomach, and from ripe honey. The chemistry is extremely complex, and compounds spanning from monoterpenes (hydrocarbons, ethers, aldehydes, acids, and bifunctional derivatives), isoprenoids, aromatic compounds (phenylpropanoids, phenols), and products degraded from fatty acids to alkaloids, were identified. Some compounds definitely stem from the plants, whereas other interesting constituents can be attributed to animal origin. Two derivatives of decanoic acid, 9-oxodec-2-enoic acid (12) and 9-hydroxydec-2-enoic acid, identified in the honey are known to be constituents of the so-called ,Queen's pheromone'. Two metabolites of these acids were identified in the extract of the honey stomach: 8-oxononanal (10), a new natural product, and 8-oxononanol (11). There structures were confirmed by synthesis. Nectar and honey stomach contain many aldehydes, which, due to the highly oxidative atmosphere in the honeycomb, are found as corresponding acids in the honey. Two acids were newly identified as 4-isopropenylcyclohexa-1,3-diene-1-carboxylic acid (14) and 4-(1-hydroxy-1-methylethyl)-cyclohexa-1,3-diene-1-carboxylic acid (15). [source] Flies and concealed nectar sources: morphological innovations in the proboscis of Bombyliidae (Diptera)ACTA ZOOLOGICA, Issue 3 2002N. U. Szucsich Abstract Bee-flies (Bombyliidae) have morphological adaptations of the mouthparts to particular floral traits. To investigate this the short, plesiomorphic proboscis of Hemipenthes morio was compared with the long, apomorphic proboscis of Bombylius major. A novel feeding position enables B. major to use flowers that open to the side as additional nectar sources. The new horizontal feeding position is enabled by the prolonged ventral base of the proboscis. Bombylius major exploits deep corolla tubes with an elongate proboscis, and an increased efficiency in both the suction pumps and the sealing mechanisms of the proboscis. The exploitation of narrow corolla tubes is made possible by the shift from a sponging feeding mode, exhibited by H. morio, to the exclusively sucking mode in B. major. Besides quantitative changes in the proportions of the different proboscis components, labellar movements as well as the structures of saliva distribution are changed along with this shift. The labial musculature of B. major does not significantly differ from the plesiomorphic state, since both examined species do not only feed on nectar, but also on pollen. [source] Forage collection, substrate preparation, and diet composition in fungus-growing antsECOLOGICAL ENTOMOLOGY, Issue 3 2010HENRIK H. DE FINE LICHT 1. Variation and control of nutritional input is an important selective force in the evolution of mutualistic interactions and may significantly affect coevolutionary modifications in partner species. 2. The attine fungus-growing ants are a tribe of more than 230 described species (12 genera) that use a variety of different substrates to manure the symbiotic fungus they cultivate inside the nest. Common ,wisdom' is that the conspicuous leaf-cutting ants primarily use freshly cut plant material, whereas most of the other attine species use dry and partly degraded plant material such as leaf litter and caterpillar frass, but systematic comparative studies of actual resource acquisition across the attine ants have not been done. 3. Here we review 179 literature records of diet composition across the extant genera of fungus-growing ants. The records confirm the dependence of leaf-cutting ants on fresh vegetation but find that flowers, dry plant debris, seeds (husks), and insect frass are used by all genera, whereas other substrates such as nectar and insect carcasses are only used by some. 4. Diet composition was significantly correlated with ant substrate preparation behaviours before adding forage to the fungus garden, indicating that diet composition and farming practices have co-evolved. Neither diet nor preparation behaviours changed when a clade within the paleoattine genus Apterostigma shifted from rearing leucocoprinous fungi to cultivating pterulaceous fungi, but the evolutionary derived transition to yeast growing in the Cyphomyrmex rimosus group, which relies almost exclusively on nectar and insect frass, was associated with specific changes in diet composition. 5. The co-evolutionary transitions in diet composition across the genera of attine ants indicate that fungus-farming insect societies have the possibility to obtain more optimal fungal crops via artificial selection, analogous to documented practice in human subsistence farming. [source] Post-ingestive effects of nectar alkaloids depend on dominance status of bumblebeesECOLOGICAL ENTOMOLOGY, Issue 4 2009JESSAMYN S. MANSON Abstract 1.,Secondary metabolites have acute or chronic post-ingestive effects on animals, ranging from death to growth inhibition to reduced nutrient assimilation. 2.,Although characterised as toxic, the nectar of Gelsemium sempervirens is not lethal to pollinators, even when the concentration of the nectar alkaloid gelsemine is very high. However, little is known about the sublethal costs of nectar alkaloids. 3.,Using a microcolony assay and paired worker bumblebees, the present study measured the effects of artificial nectar containing gelsemine on oocyte development. Oocytes are a sensitive indicator of protein utilisation and general metabolic processes. We also calculated carbohydrate concentrations in the haemolymph to examine energetic costs of gelsemine consumption. 4.,High concentrations of gelsemine significantly reduced mean oocyte width in subordinate bees, while dominant bees showed only a trend towards oocyte inhibition. Gelsemine consumption did not reduce carbohydrate concentrations in haemolymph. 5.,The cost of ingesting gelsemine may be due to direct toxicity of alkaloids or may be an expense associated with detoxifying gelsemine. Detoxification of alkaloids can require reallocation of resources away from essential metabolic functions like reproduction. The risks associated with nectar alkaloid consumption are tied to both the social and nutritional status of the bee. [source] Amino acid sources in the adult diet do not affect life span and fecundity in the fruit-feeding butterfly Bicyclus anynanaECOLOGICAL ENTOMOLOGY, Issue 4 2008FREERK MOLLEMAN Abstract 1.,In tropical forests, the adults of many butterfly species feed on fruits rather than nectar from flowers and have long life spans. Rotting fruit and nectar differ from each other in many respects, including sources of amino acids and microbial life. If amino acids in the adult diet can be used for reproduction, this may have facilitated the evolution of extended life spans in this guild. 2.,This issue was addressed by investigating effects of banana, yeast, and amino acids in the adult diet of the fruit-feeding butterfly Bicyclus anynana (Lepidoptera) on longevity and female reproductive output in two experiments. 3.,Results showed that in the fruit-feeding butterfly B. anynana: (i) banana juice, but not sliced banana or added amino acids extend life span compared with a sugar solution of similar composition; (ii) compared with this sugar solution, other cohorts (banana juice-amino acid enriched) did not have significantly higher reproductive outputs; (iii) yeast does not represent a valuable source of nutrients; (iv) caloric restriction may cause decreased life span and rate of reproduction; and (v) increased rates of reproduction have a life span cost. [source] Pollinator genetics and pollination: do honey bee colonies selected for pollen-hoarding field better pollinators of cranberry Vaccinium macrocarpon?ECOLOGICAL ENTOMOLOGY, Issue 2 2001James H. Cane Summary 1. Genetic polymorphisms of flowering plants can influence pollinator foraging but it is not known whether heritable foraging polymorphisms of pollinators influence their pollination efficacies. Honey bees Apis mellifera L. visit cranberry flowers for nectar but rarely for pollen when alternative preferred flowers grow nearby. 2. Cranberry flowers visited once by pollen-foraging honey bees received four-fold more stigmatic pollen than flowers visited by mere nectar-foragers (excluding nectar thieves). Manual greenhouse pollinations with fixed numbers of pollen tetrads (0, 2, 4, 8, 16, 32) achieved maximal fruit set with just eight pollen tetrads. Pollen-foraging honey bees yielded a calculated 63% more berries than equal numbers of non-thieving nectar-foragers, even though both classes of forager made stigmatic contact. 3. Colonies headed by queens of a pollen-hoarding genotype fielded significantly more pollen-foraging trips than standard commercial genotypes, as did hives fitted with permanently engaged pollen traps or colonies containing more larvae. Pollen-hoarding colonies together brought back twice as many cranberry pollen loads as control colonies, which was marginally significant despite marked daily variation in the proportion of collected pollen that was cranberry. 4. Caloric supplementation of matched, paired colonies failed to enhance pollen foraging despite the meagre nectar yields of individual cranberry flowers. 5. Heritable behavioural polymorphisms of the honey bee, such as pollen-hoarding, can enhance fruit and seed set by a floral host (e.g. cranberry), but only if more preferred pollen hosts are absent or rare. Otherwise, honey bees' broad polylecty, flight range, and daily idiosyncrasies in floral fidelity will obscure specific pollen-foraging differences at a given floral host, even among paired colonies in a seemingly uniform agricultural setting. [source] Air pollution impedes plant-to-plant communication by volatilesECOLOGY LETTERS, Issue 9 2010James D. Blande Ecology Letters (2010) 13: 1172,1181 Abstract Volatile organic compounds (VOCs) emitted by damaged plants convey information to undamaged neighbouring plants, and previous research has shown that these signals are effective over short distances in nature. Many herbivore-induced VOCs react with ozone, which is the most important tropospheric air pollutant in rural areas. We used extrafloral nectar (EFN) secretion as a phenotypic indicator of between-plant communication in Phaseolus lunatus L. (Lima bean) and show that an ozone-rich (80 ppb) atmosphere reduces the distance over which signalling occurs. We found that ozone degrades several herbivore-induced VOCs, a likely mechanism reducing communication distances. Direct exposure to 80-ppb ozone did not affect the VOC emissions from P. lunatus. In addition, we demonstrated that high ozone concentrations, 120 and 160 ppb, induced EFN secretion in exposed plants, whereas more moderate concentrations, 80 and 100 ppb, did not. This suggests that ozone can play a complex role in the indirect defence of P. lunatus. [source] Leaf herbivory and nutrients increase nectar alkaloidsECOLOGY LETTERS, Issue 8 2006Lynn S. Adler Abstract Correlations between traits may constrain ecological and evolutionary responses to multispecies interactions. Many plants produce defensive compounds in nectar and leaves that could influence interactions with pollinators and herbivores, but the relationship between nectar and leaf defences is entirely unexplored. Correlations between leaf and nectar traits may be mediated by resources and prior damage. We determined the effect of nutrients and leaf herbivory by Manduca sexta on Nicotiana tabacum nectar and leaf alkaloids, floral traits and moth oviposition. We found a positive phenotypic correlation between nectar and leaf alkaloids. Herbivory induced alkaloids in nectar but not in leaves, while nutrients increased alkaloids in both tissues. Moths laid the most eggs on damaged, fertilized plants, suggesting a preference for high alkaloids. Induced nectar alkaloids via leaf herbivory indicate that species interactions involving leaf and floral tissues are linked and should not be treated as independent phenomena in plant ecology or evolution. [source] Yeasts as antagonists against fireblightEPPO BULLETIN, Issue 3 2004A. Seibold Yeasts are potential antagonists of microorganisms in the phyllosphere. Due to their osmotolerance, they should also be able to colonize apple flowers. In field experiments, we applied yeast agents against fireblight at two different sites in the southern part of Germany. They showed efficiencies 0,20% below Plantomycin (streptomycin). Co-culture experiments in liquid basal media with synthetic nectar resulted in suppression of Erwinia amylovora by yeast. This effect could not be confirmed with population studies of yeasts and E. amylovora in flower clusters. Field and laboratory experiments indicated that yeasts have antagonistic properties against fireblight but further research is needed to investigate this potential. [source] FLIES AND FLOWERS IN DARWIN'S RACEEVOLUTION, Issue 1 2009Anton Pauw The idea of coevolution originated with Darwin's proposal that long-proboscid pollinators and long-tubed flowers might be engaged in reciprocal selection, but this has not been demonstrated. Here we test key aspects of Darwin's hypothesis of reciprocal selection in an experiment with naturally interacting populations of extremely long-proboscid flies (Moegistorhynchus longirostris: Nemestinidae) and long-tubed irises (Lapeirousia anceps: Iridaceae). We show that the benefit derived by both the fly (volume of nectar consumed) and the plant (number pollen grains received) depends on the relative length of their interacting organs. Each trait is shown to act both as agent and target in directional reciprocal selection, potentially leading to a race. This understanding of how fitness in both species varies in relation to the balance of their armament allows us to make tentative predictions about the nature of selection across multiple communities. We find that in each community a core group of long-tubed plant species might together be involved in diffuse coevolution with the fly. In poorly matched populations, the imbalance in armament is too great to allow reciprocal selection to act, and these species might instead experience one-sided selection that leads to convergence with the core species. Reciprocal selection drives the evolution of the community, then, additional species become attached to the network of interacting mutualists by convergence. [source] Ecology of yeasts in plant,bumblebee mutualism in Central EuropeFEMS MICROBIOLOGY ECOLOGY, Issue 2 2004Michael Brysch-Herzberg Abstract Yeast community involved in plant,bumblebee mutualism was investigated in three successive years. Yeasts were isolated from floral nectar, bumblebee queens after hibernation, bumblebee workers, and the honey provisions in nests. From the distribution of yeast species in the various microhabitats in the course of the year their ecology was assessed. Nectar of numerous plant species belonging to various plant families was analyzed in order to uncover possible impacts on the yeasts present in the nectar. Only ascomycetous yeasts were autochthonous members of the communities in the plant,bumblebee mutualism. Species in the Metschnikowia clade, the Starmarella clade, and the genera Debaryomyces and Zygosaccharomyces were associated with the mutualism. Some species appeared highly specialized, whereas others had a broader distribution. While physical and chemical properties of nectar had only limited influence on the abundance of nectar yeasts, the attractiveness of plants to the flower-visiting insects appears to have had a greater impact on the abundance and frequency of yeasts in the nectar of different plant species. [source] The evolution of floral scent: the influence of olfactory learning by insect pollinators on the honest signalling of floral rewardsFUNCTIONAL ECOLOGY, Issue 5 2009Geraldine A. Wright Summary 1.,The evolution of flowering plants has undoubtedly been influenced by a pollinator's ability to learn to associate floral signals with food. Here, we address the question of ,why' flowers produce scent by examining the ways in which olfactory learning by insect pollinators could influence how floral scent emission evolves in plant populations. 2.,Being provided with a floral scent signal allows pollinators to learn to be specific in their foraging habits, which could, in turn, produce a selective advantage for plants if sexual reproduction is limited by the income of compatible gametes. Learning studies with honeybees predict that pollinator-mediated selection for floral scent production should favour signals which are distinctive and exhibit low variation within species because these signals are learned faster. Social bees quickly learn to associate scent with the presence of nectar, and their ability to do this is generally faster and more reliable than their ability to learn visual cues. 3.,Pollinators rely on floral scent as a means of distinguishing honestly signalling flowers from deceptive ones. Furthermore, a pollinator's sensitivity to differences in nectar rewards can bias the way that it responds to floral scent. This mechanism may select for flowers that provide olfactory signals as an honest indicator of the presence of nectar or which select against the production of a detectable scent signal when no nectar is present. 4.,We expect that an important yet commonly overlooked function of floral scent is an improvement in short-term pollinator specificity which provides an advantage to both pollinator and plant over the use of a visual signal alone. This, in turn, impacts the evolution of plant mating systems via its influence on the species-specific patterns of floral visitation by pollinators. [source] The importance of scent and nectar filters in a specialized wasp-pollination systemFUNCTIONAL ECOLOGY, Issue 5 2009Adam Shuttleworth Summary 1.,Plants with open flowers and exposed nectar should attract a wide diversity of flower visitors, yet, for reasons that are not yet well understood, some plants with these ,generalist' floral traits have highly specialized pollination systems. 2.,We investigated this problem in the African milkweed Pachycarpus grandiflorus which has open flowers that produce copious amounts of exposed and concentrated nectar, yet is visited almost exclusively by spider-hunting wasps in the genus Hemipepsis. 3.,These wasps were the only visitors found to consistently carry pollinaria and a cage experiment showed that they are capable of successfully pollinating this plant. Furthermore, experimental hand-pollinations showed that P. grandiflorus is genetically self-incompatible and thus reliant on pollinators for seed set. 4.,We investigated the roles of chemical (nectar and floral scent) and spectral properties in the selective attraction of wasps and the filtering out of other potential flower visitors. Nectar palatability experiments showed that the nectar is unpalatable to honeybees but palatable to the wasps. Choice experiments conducted in the field and using a Y-maze in the laboratory showed that wasps are attracted primarily by scent rather than visual cues. Analysis of scent using Gas Chromatography-Mass Spectrometry showed that these inflorescences produce 36 different compounds, mostly monoterpenes and aliphatics. Analysis of spectral reflectance showed that flowers have similar colouring to the background vegetation. 5.,We conclude that P. grandiflorus is specialized for pollination by Hemipepsis wasps, and in the absence of morphological filters, achieves specialization through unpalatable nectar, cryptic colouring and scent as a selective pollinator attractant. 6.,This study demonstrates that plants whose flowers are not morphologically adapted to exclude particular floral visitors can achieve specialization through non-morphological filters. [source] Bigger is better: implications of body size for flight ability under different light conditions and the evolution of alloethism in bumblebeesFUNCTIONAL ECOLOGY, Issue 6 2007A. KAPUSTJANSKIJ Summary 1In social insects, reproductive success and survival of the colony critically depend on the colony's ability to efficiently allocate workers to the various tasks which need to be performed. In bumblebees, workers show a large variation of body size within a colony. Large workers tend to leave the nest and forage for nectar and pollen, whereas small workers stay inside the nest and fulfill nest duties. It was speculated that size-related differences of the sensory system might contribute to alloethism found in bumblebee colonies. 2In the first part, we investigated how body size determines eye morphology. We measured several eye parameters of Bombus terrestris workers and drones. In both, workers and drones, larger individuals had larger eyes with larger facet diameters, more ommatidia and larger ocelli. At similar body size, drones exhibited larger eyes and ocelli compared to workers. Due to theoretical considerations, we predict that large individuals with large eyes should be better able to operate in illumination conditions of lower intensity than small individuals, since ommatidial sensitivity is proportional to the square of facet diameter. 3In the second part, we tested this prediction. In a behavioural experiment, we first caught bumblebees of various sizes in the field and then determined the lowest light intensity level at which they are just able to fly under controlled laboratory conditions. We tested workers of B. terrestris and B. pascuorum, and workers and drones of B. lapidarius. Large bumblebees were able to fly under lower light levels compared to small bees, with light intensity thresholds ranging from 1·1 to 5·5 lux. 4Our results indicate that the increased light sensitivity of the visual system of large bumblebees allows them to fly under poor light conditions, for example, very early in the morning or late at dusk. This is of potential benefit to the survival of a bumblebee colony since flowers that open early in the morning usually have accumulated a relatively high amount of nectar and pollen throughout the night, and large bumblebees can utilize these resources earlier than most other bees. Thus, our findings have important implications for the understanding of the functional significance and evolution of alloethism in bumblebee colonies. [source] Dual ant attraction in the Neotropical shrub Urera baccifera (Urticaceae): the role of ant visitation to pearl bodies and fruits in herbivore deterrence and leaf longevityFUNCTIONAL ECOLOGY, Issue 2 2006H. P. DUTRA Summary 1This study investigated the protective role of ants against phytophagous insects on Urera baccifera (L.) Gaudich. Ants (22 species) visit shrubs of U. baccifera throughout the year and forage especially on leaves, where they harvest pearl bodies, and on fruiting branches, where they collect fleshy fruits. The main leaf herbivores are the butterflies Smyrna blomfildia (Fruhstorfer) and Urbanus esmeraldus (Butler), and the moth Pleuroptya silicalis (Guené). 2The proportion of vegetative (no flowers or fruits) individuals of U. baccifera occupied by ants greatly surpassed that of neighbouring plant species lacking food rewards, consistent with the hypothesis that pearl bodies act as ant attractants. Ant visitation to vegetative individuals of U. baccifera increased larval mortality of S. blomfildia, suggesting that ants attracted to pearl bodies reduce herbivore survival. Fruits were also demonstrated to play an important role in ant attraction by U. baccifera. Ant visitation to pearl body-producing shrubs of non-myrmecophytic Piper amalago L. with U. baccifera fruits attached was significantly higher than to P. amalago plants with an attached leaf of U. baccifera. 3Ant-exclusion experiments showed that ants effectively reduce the incidence of lepidopteran larvae on the plants. In both 2003 and 2004, herbivores were more abundant on ant-excluded than on ant-visited shrubs of U. baccifera. Additionally, in both years ant-excluded plants had significantly faster leaf abscission rates compared with ant-visited plants. 4So far, all ant,plant systems with dual food rewards involve extrafloral nectar as one of the attractants. This study with U. baccifera is the first to report food bodies and fruits as ant attractants in a non-symbiotic ant,plant interaction. This facultative system is also unique in that herbivore deterrence caused by pearl body- and fruit-harvesting ants can also add to leaf longevity. [source] Extrafloral nectar from cotton (Gossypium hirsutum) as a food source for parasitic waspsFUNCTIONAL ECOLOGY, Issue 1 2006U. S. R. RÖSE Summary 1For many adult nectar-feeding parasitoids food and moisture are essential for survival in the field. Early in the season, when floral nectar is not yet available in cotton, extrafloral nectar (EFN) is already present on young cotton plants. 2The parasitoid Microplitis croceipes (Cresson) can use EFN cotton plants as an only food source. The longevity and reproduction of EFN-fed female wasps was comparable to wasps fed with honey and water provided on nectariless (NL) cotton plants, and was significantly higher compared with wasps kept on NL plants with no additional food source. 3Wasps that were given preflight experiences on EFN cotton plants choose EFN cotton over NL cotton plants in two choice experiments in the flight tunnel. The parasitoids are more willing to search on an EFN plant at their second and third encounter with a plant previously visited, compared with an NL cotton plant. 4Wasps can locate EFN from short distances by its odour alone, and find it almost as fast as honey, but much faster than odourless sucrose, which is only found randomly. Experience with EFN increased the retention ability of parasitoids on a flower model. [source] Limited ability of Palestine Sunbirds Nectarinia osea to cope with pyridine alkaloids in nectar of Tree Tobacco Nicotiana glaucaFUNCTIONAL ECOLOGY, Issue 6 2004H. TADMOR-MELAMED Summary 1Secondary compounds are common in floral nectar but their relative effects on nectar consumption and utilization in nectarivorous birds are unclear. 2We studied the effect of two pyridine alkaloids, nicotine and anabasine, present in Tree Tobacco (Nicotiana glauca) nectar, on food consumption, gut transit time and sugar assimilation efficiency of the Palestine Sunbird (Nectarinia osea), a pollinator of N. glauca in east Mediterranean ecosystems. 3Sunbirds demonstrated dose-dependent deterrence; they were not deterred by the lowest natural concentrations of these alkaloids in nectar (0·1 ppm nicotine and 0·6 ppm anabasine) but they were significantly deterred by the average concentrations detected in nectar (0·5 ppm nicotine and 5 ppm anabasine). 4The two pyridine alkaloids reduced gut transit time (by 30,42%) and sugar assimilation efficiency (by 9,17%) compared with the control alkaloid-free diet. 5Sunbirds are able to cope with low, but not average, concentrations of nicotine and anabasine in N. glauca nectar. If sunbirds are efficient pollinators of N. glauca they may induce selection on it to reduce pyridine alkaloid production in the nectar. Alternatively, high concentrations in some N. glauca plants may lead the birds to visit more plants with lower alkaloid concentrations. Hence, they will be more efficient pollinators, especially if other nectar-producing plants are scarce. [source] Nectar ,theft' by hummingbird flower mites and its consequences for seed set in Moussonia deppeanaFUNCTIONAL ECOLOGY, Issue 1 2001Lara C. Summary 1,Mites (Acari: Mesostigmata: Ascidae) that live and feed in the flowers of about 100 plant species are transported in the nares of hummingbirds (Trochilidae). Mites may compete with hummingbirds for nectar secreted by the host plants, and this could affect the dynamics and reproductive outcomes of the mutualism between plants and their pollinating hummingbirds. 2,Here we combined field observations and experimental manipulations to assess the role of hummingbird flower mites (Tropicoseius sp. nov.) on nectar secretion and reproductive output of protandrous Moussonia deppeana (Schlecht. & Cham.) Hanst. (Gesneriaceae) during their flowering period in a cloud forest remnant. 3,During the 4 days that the flowers of M. deppeana last, flowers were visited exclusively by hummingbirds (Lampornis amethystinus). Bud production per inflorescence peaked in December. There were few open flowers per inflorescence in November, but numbers increased as the flowering season progressed (December and January). 4,The availability of each flower phase differed over the flowering season. Staminate-phase flowers were more abundant over the flowering season than pistillate-phase flowers. These differences were statistically significant over time. 5,Nectar availability was reduced by up to 50% in the presence of hummingbird flower mites. Over the 4 days of observation, significantly more nectar was secreted to flowers from which mites were excluded than to flowers with no mite exclusion. The same effect was observed during flowering, but mites consumed a greater percentage of the total nectar secreted in December. 6,Significantly more nectar was secreted during the staminate phase than in the pistillate phase, independent of time and treatment. 7,A manual pollination experiment suggested that mites act like secondary pollinators in this self-compatible, non-autogamous plant, at least in flowers that were not pollinated manually and had no access to pollinating hummingbirds. 8,Although seed production was not reduced significantly by flower mites, our results suggest that the presence of floral mites can affect pollen transmission, as the amount of nectar available to hummingbirds was reduced drastically. This can directly affect hummingbird foraging patterns and reduce the fitness of the host plants. [source] Temporal, spatial and biotic variations in extrafloral nectar secretion by Macaranga tanariusFUNCTIONAL ECOLOGY, Issue 6 2000Heil M. Abstract 1Many plants produce extrafloral nectar (EFN) to nourish ants and other animals which defend them against herbivores. We aimed to find reasons for the high variability in amounts of EFN produced by most plant species. We investigated the influence of several biotic and abiotic factors (time of day, leaf age, nectar removal and leaf damage) on secretion rates of EFN in the common south-east Asian pioneer tree species, Macarangatanarius (L.) Muell. Arg. 2In most experiments leaves were washed with pure water and bagged in nets to protect them against nectar-collecting insects, and nectar was collected and quantified 24 h later. Six soluble sugars and up to eight amino acids were detected in nectar samples derived from untreated, field-grown plants. Total amounts of soluble substances varied more than the relative composition of EFN. 3Nectar secretion rates were highest on young, expanded leaves. A diurnal pattern with a secretion peak in the first 2 h after dusk was detected in the field. Nectar removal had a positive effect and its accumulation a negative effect on further EFN production. Artificial leaf damage (punching leaves with a needle or removing parts of the leaf blade with scissors) led to a significant induction of EFN production for the next 3 days. 4Extrafloral nectar of M. tanarius was secreted in complex patterns influenced by different biotic and abiotic factors; its production appeared to be adapted temporally and spatially in order to ensure optimal use of invested resources. [source] Oilseed rape crops distort plant,pollinator interactionsJOURNAL OF APPLIED ECOLOGY, Issue 1 2010Tim Diekötter Summary 1. New incentives at the national and international level frequently lead to substantial structural changes in agricultural landscapes. Subsidizing energy crops, for example, recently fostered a strong increase in the area cultivated with oilseed rape Brassica napus across the EU. These changes in landscape structure affect biodiversity and associated ecosystem services. 2. Mass-flowering oilseed rape has been shown to positively affect colony growth and densities of bumblebees, which may enhance pollination services in agroecosystems. Not considered, however, have been species-specific traits of pollinators resulting in disproportionate benefits from these recurrent resource pulses. A subsequent community shift towards the subsidized species potentially distorts plant,pollinator interactions in the surrounding landscape. 3. We analysed the effects of mass-flowering crops on the abundance of legitimate long-tongued bumblebee pollinators, nectar robbing by illegitimate short-tongued bumblebees and seed set in the long-tubed flowers of red clover Trifolium pratense in 12 landscape sectors with differing amounts of oilseed rape. 4. Densities of long-tongued bumblebees visiting long-tubed plants decreased with increasing amounts of oilseed rape. The simultaneous increase of nectar robbing suggests that resource depletion is a likely explanation for this decline which may lead to a distortion in plant,pollinator interactions. The decline in long-tongued bumblebees, however, did not result in an immediate effect on seed set. In contrast, seed set increased with increasing amounts of semi-natural habitats, indicating the positive effects of these habitats on the legitimate long-tongued pollinators. 5.Synthesis and applications. Accounting for species-specific traits is essential in evaluating the ecological impacts of land-use change. The disproportional trait-specific benefits of increasing oilseed rape to short-tongued bumblebees may abet an increasingly pollinator-dependent agriculture but simultaneously threaten the more specialized and rare long-tongued species and their functions. Semi-natural habitats were found to positively affect seed set in long-tubed plants indicating that they can counteract the potentially distorting effects of transient mass-flowering crops on plant,pollinator interactions in agroecosystems. Future agri-environmental schemes should aim to provide diverse and continuous resources matching trait-specific requirements of various pollinators in order to avoid resource competition. Thereby they harmonize the economic interest in abundant pollinators and the conservation interest in protecting rare species. [source] Transgenic virus resistance in cultivated squash affects pollinator behaviourJOURNAL OF APPLIED ECOLOGY, Issue 5 2009Holly R. Prendeville Summary 1.,Two ecological risks associated with the use of transgenic crops are transgene movement into wild populations and effects on non-target organisms, such as pollinators. Despite the importance of pollinators, and their contribution to the global food supply, little is known about how they are affected by transgenic crops. Pollinator preferences affect plant mating patterns; thus understanding the effects of transgenic crops on pollinators will aid in understanding transgene movement. 2.,Honey bee and squash bee visit number and duration were recorded on conventional and transgenic virus-resistant squash Cucurbita pepo planted in a randomized block design. Floral characters were measured to explain differences in pollinator behaviour. The effect of Zucchini Yellow Mosaic Virus infection on pollinator behaviour was also examined. 3.,Honey bees visited female conventional flowers more than female transgenic flowers. Conventional flowers were generally larger with more nectar than transgenic flowers, although floral traits did not account for differences in pollinator visitation. 4.,Squash bees visited male transgenic flowers more than male conventional flowers; squash bees also spent more time in female transgenic flowers than in female conventional flowers. Transgenic flowers were significantly larger with greater amounts of sweeter nectar and they were present in greater number. Floral traits accounted for some of the variation in pollinator visitation. 5.,Squash bee visit number and duration did not differ between virus-infected and healthy plants, but this may be because pollinator behaviour was observed early in the virus infection. 6.,Synthesis and applications. Pollinator behaviour controls patterns of plant mating thus non-target effects of transgenic resistance, such as those observed here, may influence transgene movement into wild populations. These results suggest that transgenic crops should not be planted within the native range of wild relatives because pleiotropic effects may affect crop-wild hybridization and transgene introgression into wild populations. [source] | ||||||||||||||||||||||||||||||||||