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Flower longevity is an adaptive trait, optimized to balance reproductive success against the costs of flower maintenance. The trait is highly plastic in response to pollination success, and numerous studies report increased flower longevity in high elevation environments, where diversity, abundance, and activity of pollinators are low. However, few studies have experimentally investigated how flower longevity varies with pollination intensity within and among populations. We studied flower longevity of six alpine species under three pollination intensity treatments (hand-pollination, natural pollination, pollinator exclusion) at 1600 m vs. 2600 m a.s.l. at the Furka Pass, Central Swiss Alps. We hypothesized, (1) that flower longevity is generally increased in population at high elevation, and (2) that the increase in flower longevity when pollination fails is stronger in populations at high elevation compared to low elevation. Hand-pollination did not decrease flower longevity in any of the studied populations and rarely increased natural seed production suggesting no pollination limitation at both elevations. This was supported by similar pollinator visitation rates, pollinator efficiency, and pollination effectivity. Pollinator exclusion significantly increased flower longevity, but only in populations of three species at low elevation, whereby in all populations of the six species at high elevation, indicating a higher plasticity of flowers in populations at high elevation compared to populations from lower elevation. We suggest that the higher plasticity of flower longevity in alpine populations is of advantage in their unpredictable pollination environment: Increased flower longevity compensates for low pollination in unsuitable periods guaranteeing a minimum reproduction, while the capacity to senescence rapidly after successful pollination saves redundant floral costs in suitable periods.

In this commentary, we respond to a report of the EFSA GMO Panel (EFSA EFSA Supp Publ, 1) that criticises the outcomes of two studies published in this journal (Hofmann et al. Environ Sci Eur 26: 24, 2; Environ Sci Eur 28: 14, 3). Both publications relate to the environmental risk assessment and management of Bt-maize, including maize events MON810, Bt11 and maize 1507. The results of Hofmann et al. (Environ Sci Eur 26: 24, 2), using standardised pollen mass filter deposition measurements, indicated that the EFSA Panel model had underestimated pollen deposition and, hence, exposure of non-target organisms to Bt-maize pollen. The results implied a need for safety buffer distances in the kilometre range for protected nature reserve areas instead of the 20–30 m range recommended by the EFSA Panel. As a result, the EFSA Panel revised their model (EFSA EFSA J 13: 4127, 4), adopting the slope of the empirical data from Hofmann et al. The intercept, however, was substantially reduced to less than 1% at one point by introducing further assumptions based on the estimates of mainly panel members, citing possible ‘uncertainty’. Hofmann et al. (Environ Sci Eur 28: 14, 3) published extensive empirical data regarding pollen deposition on leaves. These results were part of a larger 3-year study involving detailed measurements of pollen release, dispersal and deposition over the maize flowering period. The data collected in situ confirmed the previous predictions of Hofmann et al. (Environ Sci Eur 26: 24, 2). Mean levels and observed variability of pollen deposition on maize and four lepidopteran host plants exceeded the assumptions and disagreed with the conclusions of the EFSA Panel. The EFSA Panel reacted in a report (EFSA EFSA Supp Publ, 1) criticising the methods and outcomes of the two published studies of Hofmann et al. while reaffirming their original recommendations. We respond here point-by-point, showing that the critique is not justified. Based on our results on Urtica leaf pollen density, we confirm the need for specific environmental impact assessments for Bt-maize cultivation with respect to protected habitats within isolation buffer distances in the kilometre range. Electronic supplementary material The online version of this article (doi:10.1186/s12302-017-0106-0) contains supplementary material, which is available to authorized users.

Some pollination systems, such as buzz‐pollination, are associated with floral morphologies that require a close physical interaction between floral sexual organs and insect visitors. In these systems, a pollinator's size relative to the flower may be an important feature determining whether the visitor touches both male and female sexual organs and thus transfers pollen between plants efficiently. To date, few studies have addressed whether in fact the “fit” between flower and pollinator influences pollen transfer, particularly among buzz‐pollinated species. Here we use Solanum rostratum, a buzz‐pollinated plant with dimorphic anthers and mirror‐image flowers, to investigate whether the morphological fit between the pollinator's body and floral morphology influences pollen deposition. We hypothesized that when the size of the pollinator matches the separation between the sexual organs in a flower, more pollen should be transferred to the stigma than when the visitor is either too small or too big relative to the flower. To test this hypothesis, we exposed flowers of S. rostratum with varying levels of separation between sexual organs, to bumblebees (Bombus terrestris) of different sizes. We recorded the number of visits received, pollen deposition, and fruit and seed production. We found higher pollen deposition when bees were the same size or bigger than the separation between anther and stigma within a flower. We found a similar, but not statistically significant pattern for fruit set. In contrast, seed set was more likely to occur when the size of the flower exceeded the size of the bee, suggesting that other postpollination processes may be important in translating pollen receipt to seed set. Our results suggest that the fit between flower and pollinator significantly influences pollen deposition in this buzz‐pollinated species. We speculate that in buzz‐pollinated species where floral morphology and pollinators interact closely, variation in the visitor's size may determine whether it acts mainly as a pollinator or as a pollen thief (i.e., removing pollen rewards but contributing little to pollen deposition and fertilization).

Background. Functional traits are the primary biotic component driving organism influence on ecosystem functions; in consequence, traits are widely used in ecological research. However, most animal trait-based studies use easy-to-measure characteristics of species that are at best only weakly associated with functions. Animal-mediated pollination is a key ecosystem function and is likely to be influenced by pollinator traits, but to date no one has identified functional traits that are simple to measure and have good predictive power. Methods. Here, we show that a simple, easy to measure trait (hairiness) can predict pollinator effectiveness with high accuracy. We used a novel image analysis method to calculate entropy values for insect body surfaces as a measure of hairiness. We evaluated the power of our method for predicting pollinator effectiveness by regressing pollinator hairiness (entropy) against single visit pollen deposition (SVD) and pollen loads on insects. We used linear models and AICC model selection to determine which body regions were the best predictors of SVD and pollen load. Results. We found that hairiness can be used as a robust proxy of SVD. The best models for predicting SVD for the flower species Brassica rapa and Actinidia deliciosa were hairiness on the face and thorax as predictors (R2 D0:98 and 0.91 respectively). The best model for predicting pollen load for B. rapa was hairiness on the face (R2 D0:81). Discussion. We suggest that the match between pollinator body region hairiness and plant reproductive structure morphology is a powerful predictor of pollinator effectiveness. We show that pollinator hairiness is strongly linked to pollination an important ecosystem function, and provide a rigorous and time-efficient method for measuring hairiness. Identifying and accurately measuring key traits that drive ecosystem processes is critical as global change increasingly alters ecological communities, and subsequently, ecosystem functions worldwide.

RESEARCH ARTICLE A M E R I C A N J O U R N A L O F B O TA N Y I N V I T E D PA P E R For the Special Issue: Ecology and Evolution of Pollen Performance Winning in style: Longer styles receive more pollen, but style length does not aff ect pollen attrition in wild Clarkia populations 1 Susan J. Mazer 2 , Arrash Moghaddasi , Alexandra K. Bello 3 , and Alisa A. Hove PREMISE OF THE STUDY: One proposed function of long styles is to intensify selection among male gametophytes relative to short styles. If so, given suffi - cient competition, longer styles will have higher rates of pollen tube attrition (failure to reach the style base) within the style than shorter ones. Alterna- tively, style length may infl uence pollen receipt, which itself may aff ect attrition rates. METHODS : We tested these predictions by collecting senescing styles from wild populations of two insect-pollinated Clarkia species. We examined the number of pollen grains adhering to the stigma, length of styles, and rates of attrition from the stigma surface to the stigma–style junction (SSJ), from the SSJ to the style base, and from the stigma surface to the style base. Multivariate analyses estimated the independent eff ects of pollen grains per stigma, the number of pollen tubes at the SSJ, and style length on attrition. KEY RESULTS: Style length was generally positively correlated with pollen receipt, and the number of pollen grains per stigma was positively correlated with all three attrition rates. In neither species was any attrition rate aff ected by style length independent of the number of pollen grains per stigma. CONCLUSIONS: Pollen attrition was mediated by style length, but the function of style length was primarily to increase the number of germinating pollen grains, which aff ected attrition rates either through stigma clogging or pollen–pollen interactions. Style length may have a direct eff ect on pollen receipt due to the stigma’s position relative to pollinator body parts, but traits correlated with style length may also directly aff ect pollen receipt. KEY WORDS Clarkia unguiculata ; Clarkia xantiana subsp. xantiana ; gametophytic competition; Onagraceae; pollen attrition; pollen competition; pollen deposition; sexual selection; style length Diff erences in fl oral structure and morphology among taxa and be- tween genders have been interpreted as adaptations to alternative mating systems, pollination syndromes, and gender-specifi c repro- ductive costs, and as evolutionary responses to sexual selection on traits associated with increases in male fi tness ( Bell, 1985 ; Conner et al., 1996 ; Barrett, 2002 ; Barrett and Harder, 2005 ; Jacquemyn et al., 2005 ; Carlson and Harms, 2006 ; Ruan et al., 2011 ; Temeles et al., 2012 ; Barrett and Hough, 2013 ). Similar to many fl oral traits, style length exhibits notable phenotypic variation within natural popu- lations of many homomorphic plant species (i.e., excluding het- erostylous species), as well as among taxa ( Elmqvist et al., 1993 ; Manuscript received 1 May 2015; revision accepted 14 September 2015. Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, California 93105 USA Author for correspondence (e-mail: mazer@lifesci.ucsb.edu) Present address: Biology Department, Warren Wilson College, CPO 6217 PO Box 9000, Asheville, North Carolina 28815-9000 USA doi:10.3732/ajb.1500192 Ganeshaiah et al., 1999 ; Klinkhamer and van der Veen-van Wijk, 1999 ; Sarkissian and Harder, 2001 ; Travers and Shea, 2001 ; Bernasconi et al., 2007 ; Nattero and Cocucci, 2007 ; Kulbaba and Worley, 2008 ; Nattero et al., 2010 ; Forrest et al., 2011 ; Medrano et al., 2012 ; Jia and Tan, 2012 ; Wright et al., 2012 ). Th is variation has motivated a num- ber of experimental, observational, and comparative approaches to explain its ecological function and the evolutionary signifi cance of variation both within and among species. Experimental work has identifi ed reproductive and ecological functions of style length in several species ( Mulcahy and Mulcahy, 1975 ; Johnston, 1993 ; Forrest et al., 2011 ). Within-population sur- veys have examined phenotypic correlations between style length and other traits, such as functional gender, herkogamy, the number of pollen tubes within the style, pollen deposition by different pollinators, and corolla depth ( Mulcahy, 1979 ; Campbell, 1989 ; Klinkhamer and van der Veen-van Wijk, 1999 ; Bernasconi et al., 2007 ; Nattero and Cocucci, 2007 ; Forrest et al., 2011 ; Medrano et al., 2012 ). Comparisons between species that diff er in style length have A M E R I C A N J O U R N A L O F B OTA N Y 103 (3): 1 – 15 , 2016; http://www.amjbot.org/ © 2016 Botanical Society of America • 1

Although avocado is native to Mexico, there are no comparative measures in this country on the performance of its flower visitors as pollinators. The contribution of honey bees, flies and wasps to the pollination of avocado from tropical Mexico was assessed by comparing abundance, speed of flower visitation, quantity of pollen carried per individual and pollen deposited on virgin flowers after single visits. The values of abundance and frequency of flower visitation with pollen deposition were combined to obtain a measure of pollinator performance (PP). The most abundant insects on avocado were flies (mean ± SE: 15. 2 ± 6.2), followed by honey bees (9.4 ± 6.3) and wasps (4.2 ± 3.1) (ANOVA F = 91.71, d.f. = 2,78; P < 0.001). Honey bees and wasps visited similar number of flowers (8.2 ± 3.1 and 7.5 ± 2.6 respectively), and more than flies (4.1 ± 1.2) in the same time period (F = 17.63; d.f. = 2,33; P < 0.01). Although flies carried far more avocado pollen on their bodies (44.9 ± 16.8 grains) compared with honey bees and wasps, (21.3 ± 6.2 and 23.8 ± 8.11 grains, respectively; H = 26.522, df = 2, P = 0.001), the number of pollen grains deposited on a stigma after a single visit was similar for the three taxa (2-5). There was evidence for a significant and similarly positive PP of both honey bees and flies as avocado pollinators over wasps, given their abundance, potential for pollen transport and deposition of pollen on stigmas.

Flowers of alien invasive plants can be pollen limited due to a lack of effective pollinators. The alien Impatiens glandulifera is predominantly visited by bumblebees in its invaded range. There bumblebees pollinate I. glandulifera, but it remains unclear whether foraging behaviour or bumblebee or flower morphology affects effectiveness. We investigated the effectiveness of native bumblebee (Bombus pascuorum) pollinators in Ireland by quantifying pollen deposition and removal, and seed production after a single bumblebee visit. Morphological characteristics of flowers and bumblebee body parts were measured to determine their influence on pollen deposition and removal. B. pascuorum is a highly effective pollinator of the alien due to its high visitation frequency, the morphological fit with flowers and individuals removing large pollen quantities and inducing maximum seed set after a single visit. The impact of native bumblebees on I. glandulifera pollination and the implications of the pollination mechanism of the alien for its successful spread are discussed.

Fil: Delaplane, Keith S. University of Georgia. Department of Entomology; USA. Fil: Dag, Arnon. Ministry of Agriculture. Agricultural Research Organization. Gilat Research Center; Israel. Fil: Danka, Robert G. Honey Bee Breeding, Genetics, and Physiology Research; USA. Fil: Freitas, Breno M. Universidade Federal do Ceará. Departamento de Zootecnia - CCA; Brazil. Fil: Garibaldi, Lucas Alejandro. Universidad Nacional de Río Negro. Sede Andina; Argentina. Fil: Goodwin, Mark R. Plant and Food Research. The New Zealand Institute for Plant and Food Research Limited; New Zealand. Fil: Hormaza, José I. Instituto de Hortofruticultura Subtropical y Mediterranea La Mayora (IHSM La Mayora-CSIC-UMA); Spain. Fil: Garibaldi, Lucas Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. In this chapter we present a synthesis of recommendations for conducting field experiments with honey bees in the context of agricultural pollination. We begin with an overview of methods for determining the mating system requirements of plants and the efficacy of specific pollinators. We describe methods for evaluating the pollen vectoring capacity of bees at the level of individuals or colonies and follow with methods for determining optimum colony field stocking densities. We include sections for determining post harvest effects of pollination, the effects of colony management (including glasshouse enclosure) on bee pollination performance, and a brief section on considerations about pesticides and their impact on pollinator performance. A final section gives guidance on determining the economic valuation of honey bee colony inputs at the scale of the farm or region.

Funding: School of Biology, University of St Andrews Bumblebees (Bombus spp.) are efficient pollinators of many flowering plants, yet the pollen deposition performance of individual bees has not been investigated. Worker bumblebees exhibit large intraspecific and intra-nest size variation, in contrast with other eusocial bees; and their size influences collection and deposition of pollen grains. Laboratory studies with B. terrestris workers and Vinca minor flowers showed that pollen grains deposited on stigmas in single visits (SVD) were significantly positively related to bee size; larger bees deposited more grains, while the smallest individuals, with proportionally shorter tongues, were unable to collect or deposit pollen in these flowers. Individuals did not increase their pollen deposition over time, so handling experience does not influence SVD in Vinca minor. Field studies using Geranium sanguineum and Echium vulgare, and multiple visiting species, confirmed that individual size affects SVD. All bumblebee species showed size effects, though even the smallest individuals did deposit pollen, whereas there was no detectable effect with Apis with its limited size variation. Two abundant hoverfly species also showed size effects, particularly when feeding for nectar. Mean size of foragers also varied diurnally, with larger individuals active earlier and later, so that pollination effectiveness varies through a day; flowers routinely pollinated by bees may best be served by early morning dehiscence and visits from larger individuals. Thus, while there are well-documented species-level variations in pollination effectiveness, the fine-scale individual differences between foragers should also be taken into account when assessing the reproductive outputs of biotically-pollinated plants. Publisher PDF

Entomophilous and obligate out-crossing non-native plants need to become well integrated in the resident plant–pollinator network to set seeds and become established. However, it is largely unknown how pollination patterns differ between native ranges and those where plants have been introduced. We compared the identity, abundance and visitation rates of pollinators, insect pollen loads, pollen deposition on stigmas, and fruit and seed sets of Hedysarum coronarium, an entomophilous short lived N-fixing perennial, in populations from native and introduced ranges in Spain (South of mainland Spain and Menorca Island, respectively). In both areas, Hedysarum was visited by a similar number of species, mainly hymenopterans; seven species were common between native and introduced areas. However, pollinator richness, abundance, and visits per flower were greater in the native than in the introduced range, as were fruit and seed sets. Hedysarum pollen loads on stigmas and on Apis mellifera, the most common pollinator, did not differ between areas. Lower abundance of pollinators might be causing lower visitation rates, and to some extent reducing Hedysarum fruit and seed sets in the introduced area. Our biogeographical approach shows that integration of a non-native plant in a resident pollinator network does not prevent pollen limitation in the introduced area. Therefore, despite being necessary, pollination mutualistic relationships might not be the key for non-native plant establishment success in the introduced area.

Funding: NERC studentship (CK - NE/H527291/1), St Andrews Scholarship (GB) Summary The relative importance of specialized and generalized plant-pollinator relationships is contentious, yet analyses usually avoid direct measures of pollinator quality (effectiveness), citing difficulties in collecting such data in the field and so relying on visitation data alone. We demonstrate that single-visit deposition (SVD) of pollen on virgin stigmas is a practical measure of pollinator effectiveness, using 13 temperate and tropical plant species. For each flower the most effective pollinator measured from SVD was as predicted from its pollination syndrome based on traditional advertisement and reward traits. Overall, c. 40% of visitors were not effective pollinators (range 0–78% for different flowers); thus, flower–pollinator relationships are substantially more specialized than visitation alone can reveal. Analyses at species level are crucial, as significant variation in SVD occurred within both higher-level taxonomic groups (genus, family) and within functional groups. Other measures sometimes used to distinguish visitors from pollinators (visit duration, frequency, or feeding behaviour in flowers) did not prove to be suitable proxies. Distinguishing between ‘pollinators’ and ‘visitors’ is therefore crucial, and true ‘pollination networks’ should include SVD to reveal pollinator effectiveness (PE). Generating such networks, now underway, could avoid potential misinterpretations of the conservation values of flower visitors, and of possible extinction threats as modelled in existing networks. Postprint Postprint

Background and Aims Large floral displays have opposing consequences for animal-pollinated angiosperms: they attract more pollinators but also enable elevated among-flower self-pollination (geitonogamy). The presence of sterile flowers as pollinator signals may enhance attraction while allowing displays of fewer open fertile flowers, limiting geitonogamy. The simultaneous contributions of fertile and non-fertile display components to pollinator attraction and reproductive output remain undetermined. Methods The simultaneous effects of the presence of sterile flowers and fertile-flower display size in two populations of Leopoldia comosa were experimentally assessed. Pollinator behaviour, pollen removal and deposition, and fruit and seed production were compared between intact plants and plants with sterile flowers removed. Key Results The presence of sterile flowers almost tripled pollinator attraction, supplementing the positive effect of the number of fertile flowers on the number of bees approaching inflorescences. Although attracted bees visited more flowers on larger inflorescences, the number visited did not additionally depend on the presence of sterile flowers. The presence of sterile flowers improved all aspects of plant performance, the magnitude of plant benefit being context dependent. During weather favourable to pollinators, the presence of sterile flowers increased pollen deposition on stigmas of young flowers, but this difference was not evident in older flowers, probably because of autonomous self-pollination in poorly visited flowers. Total pollen receipt per stigma decreased with increasing fertile display size. In the population with more pollinators, the presence of sterile flowers increased fruit number but not seed set or mass, whereas in the other population sterile flowers enhanced seeds per fruit, but not fruit production. These contrasts are consistent with dissimilar cross-pollination and autonomous self-pollination, coupled with the strong predispersal inbreeding depression exhibited by L. comosa populations. Conclusions Sterile flowers enrich pollination quality by promoting pollen export and import, while limiting the mating costs of geitonogamy associated with large fertile displays. Fil: Morales, Carolina Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación En Biodiversidad y Medioambiente; Argentina Fil: Traveset, Anna. Consejo Superior de Investigaciones Científicas. Instituto Mediterráneo de Estudios Avanzados; España Fil: Harder, Lawrence D.. University Of Calgary; Canadá

Background and AimsLarge floral displays have opposing consequences for animal-pollinated angiosperms: they attract more pollinators but also enable elevated among-flower self-pollination (geitonogamy). The presence of sterile flowers as pollinator signals may enhance attraction while allowing displays of fewer open fertile flowers, limiting geitonogamy. The simultaneous contributions of fertile and non-fertile display components to pollinator attraction and reproductive output remain undetermined.MethodsThe simultaneous effects of the presence of sterile flowers and fertile-flower display size in two populations of Leopoldia comosa were experimentally assessed. Pollinator behaviour, pollen removal and deposition, and fruit and seed production were compared between intact plants and plants with sterile flowers removed.Key ResultsThe presence of sterile flowers almost tripled pollinator attraction, supplementing the positive effect of the number of fertile flowers on the number of bees approaching inflorescences. Although attracted bees visited more flowers on larger inflorescences, the number visited did not additionally depend on the presence of sterile flowers. The presence of sterile flowers improved all aspects of plant performance, the magnitude of plant benefit being context dependent. During weather favourable to pollinators, the presence of sterile flowers increased pollen deposition on stigmas of young flowers, but this difference was not evident in older flowers, probably because of autonomous self-pollination in poorly visited flowers. Total pollen receipt per stigma decreased with increasing fertile display size. In the population with more pollinators, the presence of sterile flowers increased fruit number but not seed set or mass, whereas in the other population sterile flowers enhanced seeds per fruit, but not fruit production. These contrasts are consistent with dissimilar cross-pollination and autonomous self-pollination, coupled with the strong predispersal inbreeding depression exhibited by L. comosa populations. ConclusionsSterile flowers enrich pollination quality by promoting pollen export and import, while limiting the mating costs of geitonogamy associated with large fertile displays. © 2012 The Author. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved., This work was supported by the Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina and Programa Iberoamericano de Ciencia y Tecnología para el desarrollo [XII-6 to C.L.M.] and the Natural Sciences and Engineering Research Council of Canada [L.D.H.]

Palynological analysis of pollen, Pteridophyta spores and algae deposited in the superficial sediments at Lagoa de Cima and Lagoa do Campelo Lakes, located in the north of Rio de Janeiro state, was used to determine the spatial variation of the palynomorphs deposition. A total of 67 pollen types were identified at Lagoa de Cima, with an expressive contribution of regional arboreous taxa, hydrophytes and ruderal plants of the pastureland. The depositional pattern of palynomorphs depends on the fluvial leakage, the proximity of the local sedimentation to the inlet of the Imbé and Urubu Rivers and the bathymetry of lake bottom. The highest concentrations of palynomorphs were observed in the decentralized and less deeper area, without the interference of the northeastern wind. At Lagoa do Campelo, a total of 58 pollen types were identified, among which the majority of the pollen grains came from hydrophytes, with the highest concentrations found along the northeastern shore. The southeastern shore showed high percentages of pollen and spores with degraded exine and mechanical damage, due to the transport through the lakeby the currents caused by the wind, confirmed by the depositional trend of damaged palinomorphs along the same direction as the prevailing winds.A análise palinológica de grãos de pólen, esporos de Pteridophyta e algas depositados nos sedimentos superficiais da Lagoa de Cima e Lagoa do Campelo, norte do Rio de Janeiro, foi usada para a avaliação da variação espacial de deposição dos palinomorfos. Um total de 67 tipos polínicos foi identificado na Lagoa de Cima, com expressiva contribuição de taxons arbóreos regionais, plantas hidrófitas e ruderais de pastagens. O padrão deposicional dos palinomorfos está sujeito às vazões fluviais, à proximidade do local de sedimentação em relação à desembocadura dos rios Imbé e Urubu e à batimetria do leito da lagoa. As maiores concentrações de palinomorfos foram observadas em áreas descentralizadas e menos profundas, não interferindo a ação dos ventos NE. Já na Lagoa do Campelo foi identificado um total de 58 tipos polínicos, em sua maioria de grãos de pólen de hidrófitas, com área de maior concentração relacionada à borda nordeste. A borda sudoeste apresentou altas percentagens de pólen e esporos com a exina degradada e danos mecânicos, resultado da ação de correntes aquáticas impulsionadas pelo vento, confirmando ser a tendência deposicional dos palinomorfos danificados a mesma da direção dos ventos dominantes.

Species of Cucurbitaceae are cultivated worldwide and are depend on bee pollination for fruit set. Field and lab experiments were conducted at Cornell University, Ithaca, NY, during 1996 and 1997 to determine "Howden" pumpkin (Cucurbita pepo L.) pollen removal and deposition by honeybees and factors relating to male flower attractiveness. Several parameters were evaluated in flowers at anthesis: (1) removal of pollen from anthers by honey bees, (2) pollen deposition on the stigma by honey bees, (3) amount of pollen on the body of honey bees, (4) fruit set after bee pollination, and (5) male flower nectary's pores and flower attractiveness. Honey bees carried between 1,050 to 3,990 pollen grains and 13,765 were removed from an anther after one visit. The amount of pollen deposited on the stigma by the honey bees varied according to the number of visits, from 53 grains with one visit, to 1,253 grains with 12 visits, and the mean number of grains in each visit varied from 53 to 230 grains. The percentage of established fruits was higher (100%) when the flowers received 12 visits of Apis mellifera, corresponding to a load 1,253 pollen grains. The attractiveness of the male flower for pollen and nectar collection was increased by the degree of opening of the access pore to the nectary in the flower. Espécies de Cucurbitáceas são cultivadas mundialmente e são dependentes de abelhas para polinizacão e estabelecimento de fruto. Experimentos de campo e laboratório foram conduzidos na Universidade de Cornell, na cidade de Ithaca, em Nova York, durante os anos de 1996 e 1997 para determinar a remoção e deposição de pólen por abelhas em abóbora (Cucurbita pepo L.) variedade Howden e fatores relacionados com atratividade da flor masculina. Vários parâmetros foram avaliados depois da antese da flor: (1) remoção de pólen das anteras por abelhas, (2) deposição de pólen no estigma por abelhas, (3) quantidade de pólen no corpo das abelhas, (4) estabelecimento de frutos depois da polinização por abelha, e (5) atratividade da flor masculina via poros nectaríferos. Com uma visita as abelhas removeram 13.765 grãos de pólen, ficando no corpo entre 1.050 a 3.990 grãos. A quantidade de pólen depositada no estigma pelas abelhas variou de acordo com o número de visitas, de 53 grãos com uma visita, para 1.253 grãos com 12 visitas, e o número médio de grãos em cada visita variou de 53 a 230 grãos. A porcentage de frutos estabelecidos foi máxima (100%) quando as flores receberam 12 visitas de Apis mellifera, correspondendo a uma carga de 1.253 grãos de pólen. A atração da flor masculina por pólen e néctar foi aumentada pelo grau de abertura do poro do néctario da flor.

Species of Cucurbitaceae are cultivated worldwide and are depend on bee pollination for fruit set. Field and lab experiments were conducted at Cornell University, Ithaca, NY, during 1996 and 1997 to determine "Howden" pumpkin (Cucurbita pepo L.) pollen removal and deposition by honeybees and factors relating to male flower attractiveness. Several parameters were evaluated in flowers at anthesis: (1) removal of pollen from anthers by honey bees, (2) pollen deposition on the stigma by honey bees, (3) amount of pollen on the body of honey bees, (4) fruit set after bee pollination, and (5) male flower nectary's pores and flower attractiveness. Honey bees carried between 1,050 to 3,990 pollen grains and 13,765 were removed from an anther after one visit. The amount of pollen deposited on the stigma by the honey bees varied according to the number of visits, from 53 grains with one visit, to 1,253 grains with 12 visits, and the mean number of grains in each visit varied from 53 to 230 grains. The percentage of established fruits was higher (100%) when the flowers received 12 visits of Apis mellifera, corresponding to a load 1,253 pollen grains. The attractiveness of the male flower for pollen and nectar collection was increased by the degree of opening of the access pore to the nectary in the flower.

In this thesis the Weichselian history of northern Sweden is investigated, with emphasis on vegetation and climate during ice-free intervals. The main method used has been pollen analysis of sediments from pre-Late Weichselian landforms. To interpret fossil pollen assemblages, comparisons with modern pollen spectra were made. Modern pollen data were retrieved through monitoring of annual pollen deposition at seven sites in northern Sweden, from the boreal forest to above the present forest-line of birch. Eight years of pollen monitoring is described and put in a larger context through comparison with monitoring data from Iceland, Svalbard, Norway and Finland. A study of sediment cores from the Riipiharju esker shows evidence of two ice free phases during the Weichselian glacial; Tärendö I and Tärendö II. The Tärendö II ice free interval includes large climatic shifts, previously not recognized, from relatively warm conditions with Betula as the dominating pollen taxon to cold conditions with dominance of Artemisia and Gramineae and back to warmer conditions again. Correlation alternatives of the north Swedish ice free intervals Tärendö I and II are: 1/ Brörup (MIS 5c; c. 105-93 ka BP) and Odderade (MIS 5a; c. 85-74 ka BP), respectively, or 2/ Odderade and early Middle Weichselian time (MIS 3; c. 59-40 ka BP). Of these, alternative 2 is regarded as the most likely. Interstadial sediments deposited in a Veiki moraine plateau during downwasting of a pre-Late Weichselian ice sheet include only Betula dominant pollen spectra, showing that the climate during formation of the Veiki moraine was relatively warm. According to stratigraphical correlation there are three possible alternatives for Veiki moraine formation. Either it was formed during 1/ early Tärendö I, 2/ early Tärendö II, or 3/ late Tärendö II. Alternative 3 implies growth of an intermediate ice sheet reaching the eastern limit of Veiki moraine distribution during the cold phase of Tärendö II.

International audience; With the introduction of genetically modified (GM) crops, predictive tools modelling wind velocity and pollen concentration fields as well as pollen deposition rate over heterogeneous canopies are required to assess the cross-pollination rates between GM and conventional crops. Over the last decade several numerical flow models have been developed to simulate dynamic mean and turbulent fields within and above the vegetation layer. In this paper, an Eulerian advection–diffusion conservation equation for pollen particles has been incorporated into one of these flow models, Aquilon. The relative velocity between air parcels and particles is simply represented through the addition of a particle settling velocity, i.e. the particle fall velocity in still fluid. The dynamic part of this model has been previously validated in two-dimensional heterogeneous cases (roughness change, forest edge flow) and tested in a more complex three-dimensional heterogeneous case (urban forested park). In order to test the ability of this Eulerian approach to simulate accurately airborne pollen concentration and pollen deposition rate within and above heterogeneous vegetation canopies, the model is validated against two field experiments where the airborne concentration and the deposition rate of maize pollen (Zea mays) were measured downwind from source plots.We also compare the outputs of Aquilon with those of a Lagrangian model previously tested against the same dataset. Generally speaking the model performs well, with a similar accuracy to the Lagrangian model. However, both models underestimate the measured maximum in ground pollen deposition just downwind from the maize plot. It is shown that this discrepancy may be due to an underestimation of the pollen settling velocity in this region. As the Stokes number, defined as the ratio between the maize pollen response time and the characteristic time of the turbulent structures at dissipation-range scale, is about 1 in the wake region behind the source plot, it is likely that turbulence leads to an increase in the apparent settling velocity there.

International audience; Trollius europaeus (Ranunculaceae) is involved in a mutualistic interaction with several species of Chiastocheta flies (Anthomyiidae) that are both seed predators and pollinators. In the present work, the pollination biology of T. europaeus and its association with Chiastocheta were studied for 3 years in six populations along an elevational gradient in the northern French Alps. We showed that T. europaeus is mainly xenogamous and Chiastocheta represented 99 % of all visitors. We suggest that almost all seed production was achieved by these obligate seed-parasites. Despite high variability in Chiastocheta activity, the pollination service they provided was high and reliable in all populations during this 3-year study and the seed set was not pollen-limited. The ability of T. europaeus to extend flower longevity during rainy periods and a long stigmatic receptivity in the absence of pollinators may help to explain the high female reproductive success observed at all elevations. (C) Academie des sciences/Elsevier, Paris.