scholarly journals Landscape Integrity Eclipses Local Effects of Floral Resource Availability on Bumble Bee (Bombus Spp.) Abundance in a Water-Limited Island Ecosystem

2021 ◽  
Author(s):  
Andrew Simon ◽  
Brian M. Starzomski
Keyword(s):  
Resource Availability ◽  
Natural Habitat ◽  
Landscape Scale ◽  
Floral Resources ◽  
Bumble Bee ◽  
Late Season ◽  
Habitat Integrity ◽  
Matrix Habitat ◽  
Bee Community ◽  
Floral Resource

Abstract ContextHabitat loss threatens to exacerbate climate change impacts on pollinator communities, particularly in Mediterranean-type ecosystems where late season floral resource availability is limited by seasonal drought. While gardens have been found to supplement floral resources in water-limited urban landscapes, less is known about the role of natural habitat diversity in sustaining late season floral resources in more intact landscapes. ObjectivesWe investigated the importance of habitat integrity and diversity for bumble bees in a water-limited ecosystem, observing bumble bee community response to seasonal drought across gradients of disturbance and soil moisture.MethodsWe applied hierarchical models to estimate the effects of local site conditions versus landscape scale estimates of matrix habitat on bumble bee abundance. Floral resources, soil moisture, and other environmental variables were sampled along randomly distributed belt transects. Geospatial estimates of matrix habitat were derived from terrestrial ecosystem data. Bumble bees were sampled with blue vane traps.ResultsIn the late season we found that modified wet areas supported more floral resources and bumble bee workers as compared to dry semi-natural environments. Wetlands also supported more late season floral resources and bumble bee workers, though the latter effect was not significant. Despite higher levels of late season floral resources in modified wet environments, modified matrix habitat was negatively associated, and natural matrix positively associated, with workers in June and late-flying queens in July and August. We also detected differences in bumble bee community composition in disturbed versus undisturbed environments.ConclusionsThough wet modified habitats sustained the highest levels of late season floral resource availability and worker abundances in our study, bumble bee diversity and abundance were limited primarily by the availability of natural matrix habitat at the landscape scale. The conservation of natural habitat integrity and diversity can help support critical nesting and foraging habitat, and should be prioritized in efforts to foster the resilience of pollinator communities.

scholarly journals Characterizing the floral resources of a North American metropolis using a honey bee foraging assay

2019 ◽  
Author(s):  
Douglas B. Sponsler ◽  
Don Shump ◽  
Rodney T. Richardson ◽  
Christina M. Grozinger
Keyword(s):  
Honey Bee ◽  
Urban Ecosystem ◽  
Landscape Scale ◽  
Taxonomic Composition ◽  
Floral Resources ◽  
Urban Landscapes ◽  
Woody Vines ◽  
Bee Foraging ◽  
Honey Bee Foraging ◽  
Floral Resource

AbstractRoughly a third of described insect species visit flowers, making the flower-insect interface one of the chief pillars of global biodiversity. Studying flower-insect relationships at the scale of communities and landscapes has been hindered, however, by the methodological challenges of quantifying landscape-scale floral resources. This challenge is especially acute in urban landscapes, where traditional floral surveying techniques are ill-suited to the unique constraints of built environments. To surmount these challenges, we devised a “honey bee foraging assay” approach to floral resource surveying, wherein continuous colony weight tracking and DNA metabarcoding of pollen samples are used to capture both the overall availability and taxonomic composition of floral resources. We deploy this methodology in the complex urban ecosystem of Philadelphia, PA, U.S. Our results reveal distinct seasonality of floral resource availability, with pulses of high availability in May, June, and September, and a period of prolonged scarcity in August. Pollen genus richness mirrored this pattern, with peak richness in May and June. The taxonomic composition of pollen samples varied seasonally, reflecting underlying floral phenology, with especially strong turnover between May and June samples and between August and September samples delineating well-defined spring, summer, and fall floral resource communities. Trait analysis also revealed marked seasonal structure, with spring samples characterized by trees and shrubs, summer samples including a stronger presence of herbaceous “weeds”, and fall samples dominated by woody vines. Native flora predominated in spring, giving way to a preponderance of exotic flora in summer and fall. Our study provides a detailed portrait of floral resources in a complex urban environment. At a basic level, this yields insight into the assembly of novel urban floral resource communities, showcasing, for example, the emergence of a woody-vine-dominated fall flora. At an applied level, our data can inform urban land management, such as the design of ecologically functional ornamental plantings, while also providing practical guidance to beekeepers seeking to adapt their management activities to floral resource seasonality. Methodologically, our study demonstrates the potential of the honey bee foraging assay as an efficient and standardizable technique for landscape-scale floral resource surveying.

scholarly journals Exploitative competition and displacement mediated by eusocial bees: experimental evidence in a wild pollinator community

2020 ◽  
Vol 74 (12) ◽  
Author(s):  
Veronica R. Wignall ◽  
Matthew Brolly ◽  
Cassandra Uthoff ◽  
Kala E. Norton ◽  
Hannah M. Chipperfield ◽  
...  
Keyword(s):  
Resource Availability ◽  
Resource Competition ◽  
Landscape Management ◽  
Resource Depletion ◽  
Floral Resources ◽  
Exploitative Competition ◽  
Ecological Release ◽  
Pollinator Community ◽  
Eusocial Bees ◽  
Floral Resource

Abstract Eusocial bees are likely to be ecologically important competitors for floral resources, although competitive effects can be difficult to quantify in wild pollinator communities. To investigate this, we excluded honeybees (HBE treatment), bumblebees (BBE) or both (HB&BBE) from wild-growing patches of bramble, Rubus fruticosus L. agg., flowers in two eight-day field trials at separate locations, with complementary mapping of per-site local floral resource availability. Exclusions increased per-flower volume of nectar and visitation rates of non-excluded bees, compared to control patches with no bee exclusions (CON). There was a large increase in average nectar standing crop volume both at Site 1 (+ 172%) and Site 2 (+ 137%) in HB&BBE patch flowers, and no significant change in HBE or BBE, compared to CON patches. Foraging bee responses to exclusion treatments were more pronounced at Site 2, which may be due to lower local floral resource availability, since this is likely to increase the degree of exploitative competition present. Notably, at Site 2, there was a 447% increase in larger-bodied solitary (non-Apis/Bombus) bees visiting HB&BBE patches, suggesting ecological release from competition. Hoverflies showed no response to bee removals. Numbers of other non-bee insect groups were very small and also showed no clear response to exclusions. Our findings reveal patterns of competitive exclusion between pollinator groups, mediated by resource depletion by eusocial bees. Possible long-term implications of displacement from preferred flowers, particularly where alternative forage is reduced, are discussed. Significance statement Understanding patterns of exploitative competition and displacement is necessary for pollinator conservation, particularly for vulnerable or threatened species. In this research, experimental methods reveal underlying patterns of resource competition exerted by eusocial bees in a wild pollinator community. We show that honeybees and bumblebees competitively displace each other and particularly solitary (non-Apis/Bombus) bees from bramble, an important native nectar and pollen source. Effects were stronger where local floral resource availability was identified to be limited. Notably, following experimental exclusion of both honey- and bumblebees from flowers, visitation by solitary bees increased by up to 447%, strongly suggesting ecological release from competition. These results highlight the need for informed landscape management for pollinator wellbeing, including appropriate honeybee stocking densities and improved floral resource availability.

scholarly journals Floral resources and habitat affect the composition of hummingbirds at the local scale in tropical mountaintops

2015 ◽  
Vol 75 (1) ◽  
pp. 39-48 ◽  
Author(s):  
LC Rodrigues ◽  
M Rodrigues
Keyword(s):  
Species Composition ◽  
Relative Abundance ◽  
Resource Availability ◽  
Positive Relationship ◽  
Feeding Habits ◽  
Local Scale ◽  
Floral Resources ◽  
Community Based ◽  
Abundance And Diversity ◽  
Floral Resource

Hummingbird communities tend to respond to variation in resources, having a positive relationship between abundance and diversity of food resources and the abundance and/or diversity of hummingbirds. Here we examined the influence of floral resource availability, as well as seasonality and type of habitat on the composition of hummingbird species. The study was carried out in two habitats of eastern Brazilian mountaintops. A gradient representative of the structure of hummingbird community, based on species composition, was obtained by the ordination of samples using the method of non-metric multidimensional scaling. The composition of hummingbird species was influenced by the type of habitat and floral resource availability, but not by seasonality. Hummingbird communities differ between habitats mainly due to the relative abundance of hummingbird species. The variation in composition of hummingbird species with the variation in floral resource availability may be related to differences in feeding habits of hummingbirds. Hummingbird species with the longest bills visited higher proportions of ornithophilous species, while hummingbirds with shorter bills visited higher proportions of non-ornithophilous species. The results demonstrate that at local-scale the composition of hummingbird species is affected by the type of habitat and floral resources availability, but not by seasonality.

scholarly journals Novel data support model linking floral resources and honey bee competition with bumble bee abundances in coastal scrub

2021 ◽  
Vol 27 ◽  
Author(s):  
Diane M Thomson
Keyword(s):  
Apis Mellifera ◽  
Statistical Model ◽  
Honey Bees ◽  
Floral Resources ◽  
Bumble Bee ◽  
Mechanistic Models ◽  
Pollination Services ◽  
Forage Plants ◽  
Time Period ◽  
Floral Resource

Growing evidence supports that many bee populations are declining, with potentially serious consequences for pollination services. Mechanistic models that predict bee abundances from drivers like floral resource availability can be a powerful way to understand and address declines, but remain rare and largely unvalidated. I used temporally and spatially novel data to validate previous analyses linking bumble bee (Bombus spp.) declines in California coastal scrub with loss of floral resources, mediated by drought and competition with non-native honey bees (Apis mellifera). New observations from 2015-2018 were combined with data from 1999-2014 to further test these mechanistic hypotheses and evaluate predictions of a statistical model for Bombus abundances. As predicted, positive associations between spring rainfall and floral abundances and between Bombus and key forage plants were consistent between time periods. Increased A. mellifera abundance corresponded with reduced Bombus use of the most abundant forage plant and lower Bombus abundances in the following year. Quantitative predictions from the Bombus statistical model previously developed for 1999-2014 were relatively unbiased and strongly rank correlated with either spatially or temporally novel data. However, the model consistently underpredicted Bombus abundances when both flower patch and time period were novel. Overall, four new years of data further strengthen evidence that loss of floral resources due to drought and competition with feral Apis mellifera is an important cause of Bombus decline in this habitat. These findings reinforce the value of even simple models that are mechanistically framed, both in understanding past patterns of change and for qualitative prediction. 

scholarly journals FLORAL BIOLOGY AND BEEKEEPING POTENTIAL OF Croton heliotropiifolius KUNTH (EUPHORBIACEAE) AT SEMI ARID REGION, BRAZIL1

2021 ◽  
Vol 34 (4) ◽  
pp. 895-903
Author(s):  
VANDERLEI DA SILVA OLIVEIRA ◽  
JOSÉ MONTEIRO DO NASCIMENTO JÚNIOR ◽  
RICARDO LANDIM BORMANN DE BORGES ◽  
LUCIENE CRISTINA LIMA E LIMA
Keyword(s):  
Apis Mellifera ◽  
Resource Availability ◽  
Arid Region ◽  
Pollen Grains ◽  
Floral Biology ◽  
Floral Resources ◽  
Flower Production ◽  
Semi Arid Region ◽  
Floral Resource ◽  
Semi Arid

ABSTRACT The aim of the present study was to determine the beekeeping potential of Croton heliotropiifolius Kunth (Euphorbiaceae) based on flowering strategy, floral characteristics, available floral resources, and the individuals frequencies and foraging activities of Apis mellifera L. on its flowers in Fazenda Ingazeira, Brazil. Each C. heliotropiifolius plant possessed inconspicuous diclinous flowers clustered into 560 ± 60 dense terminal inflorescences containing 59 ± 12 pistillate and 160 ± 26 staminate flowers. Although both types of flowers produced nectar (pistillate: 2.8 ± 0.8 μL ; staminate: 0.3 ± 0.06 μL ), A. mellifera workers mostly visited staminate flowers (98%) during the peak visitation period (08:00-11:00 h). Moreover, during the foraging period, each plant produced approximately 5.376 × 10 8 pollen grains, ensuring approximately 33 visitation cycles from a colony of A mellifera workers that picked up an average of 405 pollen grains per visit per flower. Further, C. heliotropiifolius showed an annual cornucopia flowering strategy with high flower production for five months, which is an important characteristic that ensures floral resource availability in the environment. These findings suggest that C. heliotropiifolius has a great potential for apiculture in this region.

Changes in Land Use and Land Cover Along an Urban-Rural Gradient Influence Floral Resource Availability

2021 ◽  
Author(s):  
Lauren Lynch ◽  
Madeline Kangas ◽  
Nikolas Ballut ◽  
Alissa Doucet ◽  
Kristine Schoenecker ◽  
...  
Keyword(s):  
Land Use ◽  
Land Cover ◽  
Resource Availability ◽  
Urban Rural ◽  
Floral Resource

scholarly journals Salvage of floral resources through re-absorption before flower abscission

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Graham H. Pyke ◽  
Zong-Xin Ren ◽  
Judith Trunschke ◽  
Klaus Lunau ◽  
Hong Wang
Keyword(s):  
Floral Resources ◽  
Floral Nectar ◽  
Nectar Volume ◽  
Flower Colours ◽  
Nectar Concentration ◽  
Nectar Sugar ◽  
Biochemical Mechanisms ◽  
Floral Resource ◽  
Almost All

Abstract Plants invest floral resources, including nectar and pigment, with likely consequent reproductive costs. We hypothesized that plants, whose flowers abscise with age, reabsorb nectar and pigment before abscission. This was tested with flowers of Rhododendron decorum, which has large, conspicuous white flowers that increasingly abscise corollas as flowers age. As this species is pollinated by bees, we also hypothesized that nectar concentration would be relatively high (i.e., > 30% wt/vol) and petals would contain UV-absorbing pigment. Floral nectar volume and concentration were sampled on successive days until abscission (up to ten days old, peak at five days) and for sub-sample of four-day-old flowers. Flowers just abscised were similarly sampled. Flower colours were measured using a modified camera, with recordings of spectral reflectance for abscised and open non-abscised flowers. Pigment content was summed values of red, green, blue channels of false color photos. As expected, flowers reabsorbed almost all nectar before abscission, separately reabsorbing nectar-sugar and nectar-water, and petals contained UV-absorbing pigment. However, flowers did not reabsorb pigment and nectar-concentration was < 30% wt/vol. That flowers reabsorb nectar, not pigment, remains unexplained, though possibly pigment reabsorption is uneconomical. Understanding floral resource reabsorption therefore requires determination of biochemical mechanisms, plus costs/benefits for individual plants.

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