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Flash talk abstracts

Friday 25 October

F.08 Influence of floral resources availability on pollinator abundance in Irish farmland

Irene Bottero, Simon Hodge, Jane Stout Trinity College Dublin, Dublin, Ireland

In Ireland, the main pollinators are managed bees, solitary bees, bumble bees and hover flies. More than half of both bumble bees and solitary bees are in decline. A cause of pollinators decline has been identified in the habitat degradation and intensification of agriculture. In Ireland, more than the 60% of the landscape is farmed, and the east part of the country is mainly composed of intensively managed crop and pasture lands. The shift from the semi-natural habitat into a landscape characterised by an intensive agriculture implies an alteration in the vegetation that might affect the availability of food resources for pollinators, with repercussion on their density, behaviour and movements. In this context, and as part of the EU-funded PoshBee project, we aimed to investigate if the end of the flowering period of the entomophilous, mass-flowering crops affected pollinator communities. Our hypothesis was that, due to the fact that the flowering period of the crops is the main resources of food for pollinators in the Irish agricultural landscape, the insect communities changed during and after the blossoming. In order to test our hypothesis, six oilseed rape crops and five apple orchard sites were selected throughout Ireland, and their pollinator populations were recorded during and after the crop flowering period. Furthermore, in order to better investigate the important role of the boundaries of agricultural fields in terms of provision of food, we also recorded the abundance and richness of floral resources along the margins, as well as the floral species that the individuals were feeding on. In this presentation, we will outline our preliminary findings.

F.09 Urban pollinators - Solitary bees in Freising

Julie Weissmann, Hanno Schäfer Plant Biodiversity Research Group, Technical University of Munich, Munich, Germany

The project uses a holistic approach integrating pollinators, plants and people in a large town and aims to answer three main questions: 1) How important are urban habitats for applied bee conservation? 2) How relevant is bee diversity for urban fruit crop pollination? 3) How can urban citizens become involved in urban bee research? The study was carried out in a large town in southern Germany. Occurrence data of target specialized bee species was collected on existing and newly established flower patches throughout the city. Flower visitors were recorded through systematic observations on rosaceous fruit crops flowering throughout the season. Students and citizen scientist were trained to perform pollination observations on fruit crops and search for selected target bee species. Occurring and newly introduced food sources are used by some of the specialized and therefore particularly vulnerable bee species. The crop flower visitor community composition varied strongly throughout the season and between plant species. Participation by urban citizens in bee identification trainings was high, the contribution through observation reports was low. We conclude that 1) cities can contribute to target species conservation for some specialized bee species; 2) an urban food security perspective highlights the importance of protecting diverse bee communities in urban environments; 3) participative approaches in urban bee research have an educational impact but taxonomic difficulties raise specific challenges for citizen scientists.

F.14 Natural selection on floral traits of two Penstemon species

Kaushalya Rathnayake1, Amy Parachnowitsch1,2 1 University of New Brunswick, Canada 2 Uppsala University, Sweden

Natural selection on floral traits is fairly commonly observed, however much of the focus has been on visual signals. We measured floral traits of two Penstemon species in the Colorado Rockies to ask whether selection on visual or olfactory signals is more prevalent and whether these two bee-pollinated plants experience similar selection pressures. Both P. strictus and are typical purple flowers common for bee-pollination, and we will compare these species to previously studied P. digitalis where selection on scent was stronger than many visual signals but unlike these species have mostly white corollas.

F.15 Floral trait differentiation in the Anacamptis coriophora group: phenotypic selection on scents, but not on colour

Nina Joffard1, Iris Le Roncé2, Julien Renoult2, Bruno Buatois2, Laurent Dormont2, Bertrand Schatz2 1 EBC, University of Uppsala, Sweden 2 Centre d'Ecologie Fonctionnelle et Evolutive (CEFE), Montpellier, France

Divergent selective pressures imposed upon floral traits may promote floral divergence and speciation in flowering plants. However, whether current divergent selection contributes to the maintenance of floral trait differentiation among closely related plant taxa remains to be tested. In this study, we compared floral phenotypes, pollinator guilds and selective pressures imposed upon floral traits among three closely related orchid taxa, namely Anacamptis coriophora subsp. coriophora, A. fragrans and A. coriophora subsp. martrinii. We showed that these three taxa were characterised by different floral colours and scents, with two predominant compounds per taxon, one shared among all three taxa and one taxon-specific. Floral display size was positively correlated with fruit set in most populations, while we found no apparent link between floral colour and female reproductive success. We detected positive selection on several taxon-specific compounds in A. fragrans, whereas no selection was found on floral volatiles of A. coriophora. Our results suggest that present-day phenotypic selection contributes to the maintenance of chemical differentiation between A. coriophora and A. fragrans, but that other evolutionary forces likely drove floral colour divergence in this orchid group.

F.16 Butterflies, bumblebees and hoverflies are equally effective as pollinators of Knautia arvensis (Caprifoliaceae), a generalist plant species with compound inflorescences

Jeff Ollerton1, Emma Coulthard2, Sam Tarrant3, Fergus Chadwick4, James Woolford5, André Rodrigo Rech6 1 University of Northampton, United Kingdom 2 Manchester Metropolitan University, United Kingdom 3 RSPB, United Kingdom 4 University of Glasgow, United Kingdom 5 University of Northampton, United Kingdom 6 Universidade Federal dos Vales do Jequitinhonha e Mucuri, Brazil

Interactions among plants and pollinators vary on a continuum from complete specialization (a single pollinator species for a given plant species) to highly generalised (different functional groups of pollinators perform equivalent services for a given plant species). Moreover, these interactions vary in time and space, giving rise to complex ecological scenarios. Despite this, there is a long-held assumption that bees, particularly large ones such as bumblebees (Bombus spp.), are usually the most effective pollinators of generalist plants. We tested this assumption by studying how the relative importance of different groups of pollinators of Knautia arvensis (L.) Coult. (Caprifoliaceae: Dipsacoideae) varied across years and flower density in the same population. The main questions were: 1. Are the principal groups of pollinators of K. arvensis consistent in their relative abundance over time? 2. How effective are these groups at pollinating this plant? We studied low and high density populations of Knautia arvensis in Northampton, UK. To assess pollinator importance, we exposed virgin inflorescences to single visits by different types of pollinators and then combined the effectiveness (proportion of stigmas with pollen after a single visit) of each pollinator group with the proportional visitation frequency in five different years. We also compared pollinator behaviour (time spent on flowers and flight distance between visits). The relative importance of each pollinator group varied considerably between years. Different groups varied in flight distances between flower visits, and all were influenced by flower density, with shorter average flights in high-density patches. Butterflies were the best pollinators in terms of the proportion of stigmas pollinated and flight distance between flower visits, although their variable frequency prevented them from being the most important pollinators in all years. Our results reinforce the adaptive value of generalised pollination strategies when variation in relative abundance of different types of pollinators is considered.

F.21 Plant-pollinator interactions in cultural landscapes during urbanisation

Marie V. Henriksen, Line Johansen Norwegian Institute of Bioeconomy Research, Norway

Land use change from semi-natural habitats into urban areas poses a threat to both local and global diversity of species and their interactions. The BE(E) DIVERSE project aims to provide knowledge to help safeguard biodiversity in cultural landscapes during urbanisation with focus on plants and key pollinators (bees and hoverflies) and their interactions in Trondheim, Norway. The function of semi-natural grasslands as hot spots for grassland specialist plants and insect pollinated plants in the urban landscape was examined, as well as the potential for other nature types to function as stepping stones for pollinators and their plant resources. Plants surveys revealed semi-natural grassland as hot spot habitats for both habitat specialists and insect pollinated plants while road verges were particularly rich in insect pollinated plants and therefore have the potential to function as stepping stones for pollinators. Flowering plants, pollinators and their interactions were then sampled at 14 sites along gradients of increasing urbanisation with each site containing both a hot spot (semi-natural grasslands) and potential stepping stone (road verges) habitat within a 500m radius. Three times during the summer, floral resource abundance and pollinator diversity was estimated along a 100m transect. Plant-pollinator interactions were sampled as pollen collected from the bodies of bees and hoverflies. The effect of urbanisation and land use on distribution patterns on plants and pollinators will be quantified in a joint species distribution model while the effects on plant-pollinator interactions will be assessed in a pollen transport network. This will help inform urban land use planning to maintain and restore biodiversity of plant and pollinators.

F.22 The importance of native honeybees in wild plant communities; the case of a South African biodiversity hotspot

Dara A. Stanley1, Simangele Msweli2, Steven D. Johnson2 1 School of Agriculture and Food Science, University College Dublin, Dublin 4, Ireland 2 School of Life Sciences, University of KwaZulu-Natal, Scottsville, Pietermaritzburg, South Africa

Western honeybees (Apis mellifera L.), native to Europe and Africa, have been transported worldwide and are now one of the most important global crop pollinator species. Although the relative contribution of honeybees to global crop pollination is increasingly recognised, relatively little is known about their importance as pollinators in wild plant communities. The only remaining significant wild and unmanaged western honeybee populations are in Africa. We investigated the importance of honeybees as pollinators of diverse wild plant communities in the Maputaland-Pondoland-Albany Biodiversity hotspot in South Africa. Honeybees visited a large proportion of flowering plant species within these two communities (40% and 35%) and also provided a substantial proportion of visits to the plants they visited (40% and 32% respectively). However, when pollinator importance indices (based on abundance, pollen loads, fidelity and efficiency) were calculated for a subset of plants, honeybees were only important pollinators of 29% of the plants they visited. Our data provide a first step in determining the importance of honeybees as pollinators in wild plant communities, and the potential impacts of honeybee declines on these highly diverse grassland ecosystems.

F.23 Evaluating the predictive performance of models explaining pollinator abundance in mass-flowering crops

Maria Blasi Romero, Yann Clough Centre for Environmental and Climate Research (CEC), Lund University, Sweden

Modelling pollinators is a way to identify priorities and problems on how to deal between pollination and biodiversity conservation. Global models that can predict bee responses in the landscape are needed to develop better agro-environment policies that will help to mitigate the loss of these ecosystem services agents. However, the existing knowledge for ecological predictions on ecosystem services generally comes from other regions, and therefore it restricts the ability to make use of the existing knowledge to inform policy and management. Knowing to what degree models are transferable is a prerequisite to increase ecological understanding. We used existing data on bumblebee and solitary bee abundance at different regions and spatial scales, and high-resolution land use information. Data includes pollinator observations in focal oilseed rape fields in 4 different countries (Sweden, Germany, The Netherlands, and the UK), data from different years (2011, 2012, 2013), and different studies (4 different studies). In this study, we assessed the contribution of land-use variables to the prediction of wild pollinator abundance in oilseed rape, the consistency in the effects, and the transferability of these models between countries and years.

Saturday 26 October

F.33 Resource use among bumblebees and honeybees across spatial and temporal scales in Norway

Rakel Blaalid, Sondre Dahle, Graciela Rusch, Frode Fossøy. Norwegian Institute for Nature Research (NINA), Norway

The assessment of the flower resources used by pollinators can help understand several aspects of plant-pollinator interactions of significance for the conservation of plants and pollinators and for the ecosystem services they generate. However, there are still major knowledge gaps about the ecology of plant-pollinator interactions such as foraging distances of pollinators, host-specificity, and the phenology of flowering and pollinator activity. These factors are challenging and time consuming to assess with observational field assessments. DNA metabarcoding opens a wide range of opportunities for addressing these ecological questions. We present a study where we have combined field observations of flower visitation and pan-trap data with DNA metabarcoding of pollen from domestic bee-hives. We surveyed 120 highly urban to moderately urban areas in Oslo in 2017 and collected pollen from 17 beehives in the time period June-September to investigate the recourse use of wild and domestic pollinators. Among the 47 bee species included in the results, honeybees are the dominating species in terms of flower visitation rate. Based on the pollen DNA barcoding we found that the resource use of honey bees is skewed towards typical garden plants, often rich in resources. We also found sharp shifts in pollen composition during the season. However, there is variation among hives in both plant groups and the amount of pollen gathered, indicating strong spatial differences in resource availability in Oslo.

F.34 Pollination by intoxication – how alkaloids influence bumblebees’ pollinating behaviour

Judit Linka University of Greenwich, United Kingdom

Many flowering plants produce alkaloids which are present in different parts of the plants and in the nectar. Through the alkaloids within the nectar the behaviour of pollinators can be modified to the benefit of the plant. I’m interested how these naturally occurring alkaloids, primarily glaucine and caffeine influence the primary robbing behaviour of bumble bees. Initial results with glaucine indicate, contrary to expectations that this alkaloid doesn’t deter buff tailed bumble bees from primary robbing. Further experiments are investigating how caffeine alters the primary robbing behaviour of buff tailed bumble bees on Linaria vulgaris. Parallel with these lab experiments I am undertaking field observations of Salvia ‘Hot Lips’ flowers which are commonly primary robbed by buff tailed bumble bees.

F.41 Pesticide residues in nectar and pollen collected from plants: A preview.

Elena Zioga1, Blánaid White2, Jane Stout1 1 Botany, School of Natural Sciences, Trinity College Dublin, Dublin, Republic of Ireland, 2 School of Chemical Sciences, Dublin City University, Dublin, Republic of Ireland

The exposure to pesticides (fungicides, herbicides and insecticides) is a significant stressor for bees and other pollinators, and has recently been the focus of intensive debate and research. Specifically, the dietary exposure through consumption of contaminated pollen and nectar is considered significant, as it presents the highest index of the likelihood of pesticide exposure across all the bee species. Although the residues found on those matrices directly collected from plants were found to be higher compared to those collected by the bees (before they enter in the hive), the actual risk that multiple pesticide residues might pose to non-target species is difficult to assess due to the lack of clear evidence of their precise exposure. Moreover, the amounts of pesticide residues in nectar and pollen may be highly variable, since studies in this field are influenced by various factors, including the crop type, the application method, the chemical properties of a compound and the abiotic environmental factors. To consolidate the existing knowledge of the field-realistic residues detected in pollen and nectar directly collected from plants, we performed a systematic literature review of studies over the past 50 years (1968-2018), and we will discuss the results of this analysis which indicate that even though pollen was the matrix evaluated the most, nectar seems to be more contaminated. The majority of pesticides were detected in the family of Asteraceae, and even though the compounds that were evaluated the most belong to the category of neonicotinoids (insecticides), the group of fungicides prevailed upon the rest pesticide categories.

F.42 The distribution of insect pollinators in an oil palm plantation

Knut Hessen1, Anne Krag Brysting2, Douglas Sheil3, Anders Nielsen2 1 University of Oslo, Oslo, Norway 2 Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Norway 3 Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, Campus Ås, Norway

Oil palm plantations cover approximately 10% of the world´s permanent croplands, with Indonesia accounting for more than 53% (33.5 Mt) of global palm oil production. Oil palm is one of the world’s most rapidly expanding crops and there continues to be an increase in vegetable oil and biofuel demands. Expansion of agricultural monocultures negatively affects all aspects of biodiversity including insects. Insects are the most important pollinator for tropical plant species, pollinating approximately 98-99% of all plants in this biome. The oil palm company, PT Austindo Nusantara Jaya, is relatively conservation minded. One of the company`s goals is to keep patches of so called “high conservation value forest” left inside their plantations. This study focused on one of their plantations, a 16,620 hectares area in Ketapang, West Kalimantan, Indonesia, run by PT Kayung Agro Lestari (KAL). This plantation holds several small patches of “close to native forest”. The aim of the study is to assess whether there is an increase in pollinator density and diversity in relation to forest patch proximity. I collected insect pollinators by use of pan traps placed at understory vegetation height from June to October 2017. I sampled around two forest patches and in two control sites situated about 2 km from any forest. The data collected in this study should allow managers to make more informed decisions concerning insect pollinator conservation in relation to oil palm plantation establishment, management and development. Some preliminary results from this and another study, focusing on pollinator distribution in the same area, will be presented.

F.43 Is floral longevity depending on flower size, climate or phylogeny?

Noemí Pérez, Rubén Torices, Marcos Méndez Area of Biodiversity and Conservation, Universidad Rey Juan Carlos, Móstoles (Madrid), Spain

Floral longevity is a key component of floral display. Individual fitness benefits from higher floral longevity due to higher floral display or more visits by pollinators, but keeping flowers open can entail costs, particularly in warm climates and/or large flowers. Using a literature search, we gathered information on floral longevity of 177 plant species from 55 families. When possible we also compiled information on geographic coordinates, habitat and floral length/diameter. Floral longevity ranged from minutes to ca. one month. We did not find any correlation between floral longevity and latitude or habitat. We found a negative correlation between log floral longevity and floral size, that held even after phylogenetic correction. There was a significant phylogenetic signal (K = 0.14) indicating that related species tend to have floral longevities more similar than expected from their phylogenetic relatedness. This signal is remarkable due to the low number of species of the same family in our data set and indicates that floral longevity could be a conserved trait at the family level.

F.44 Combined effects of pollen viability and pollinator efficiency on seed set in red clover cultivars

Veronica Hederström Swedish University of Agricultural Sciences, Sweden

Clover seed is used in the agricultural sector for animal fodder production and provision of green manure. Availability of organic clover seed is vital for the organic farming sector. However, poor and variable seed set is a persistent problem, particularly among tetraploid red clover cultivars. As clover rarely self-pollinates, pollen transfer by insect pollinators is necessary for good seed set. This in turn, depends on the density and pollination efficiency of pollinators. Long-tongued bumblebees may be most valuable for ensuring a high seed set in red clover, but recent studies have demonstrated dramatic shifts in density and composition of bumblebee communities towards more short-tongued species with higher propensity towards nectar robbing. This could lead to lower pollination rates, especially in tetraploids, which have larger flowers with deeper corolla tubes. In addition, studies suggest that pollen germination and fertilization potential is lower in tetraploid red clover. Pollinator communities will be affected by location and season, and thus there could be a strong interaction between ploidy, geographic locality, and flower phenology, with some cultivars being especially sensitive. In this study we have tried to determine the effects of these factors, including interactions between pollinator community composition and clover cultivar, as well as variation in pollen viability among cultivars and its contribution to low seed set. For different red clover cultivars we investigated floral shape, nectar volume, pollen germination success and pollinator behaviour. Furthermore, we investigated seed set and the amount of pollen deposited on the flower stigma after visitation by 8 different pollinator species with 3 tongue lengths: short (< 8mm), medium (8-9 mm) and long (> 9 mm).

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