The Effect of Local Flower Distribution on the Foraging and Communication Behavior of the Common Eastern Bumblebee, Bombus Impatiens PDF Download
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Author: Anthony P Lange
Publisher:
ISBN:
Category : Bumblebees
Languages : en
Pages : 40
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Author: Anthony P Lange
Publisher:
ISBN:
Category : Bumblebees
Languages : en
Pages : 40
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Author: Jeremy Hemberger
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Bumble bees are a critical group of flower-visiting insects that provide pollination services to a diversity of wild and commercial plants. Recently, a number of formerly common species of North American bumble bees have shown evidence of precipitous declines in range and relative abundance, adding ongoing concern regarding the stability of pollinator populations writ large. While a number of factors have been implicated in bumble bee declines, the loss of habitat as a result of expansion and intensification of agricultural lands is of utmost concern. As agricultural lands have supplanted flower-rich natural habitat such as prairies and wetlands, the location, amount, and timing of floral resource availability has been dramatically altered. Thus far, our understanding of how the combination of where flowers are in space and time is poorly understood, particularly in the context of how changes have impacted the bumble bees dependent on floral resources. As such, the objective of this dissertation is to enhance our understanding of how changes in spatiotemporal resource abundance impact bumble bee behavior, colony growth and reproduction, and population trends over the course of agricultural change in US midwestern landscapes - with a particular focus on Wisconsin agroecosystems using the common eastern bumble bee (Bombus impatiens Cresson) as a model species in laboratory and field experiments. Throughout this work, I have revealed that the temporal availability of floral resources in agricultural landscapes impacts bumble bee foraging behavior and colony growth and reproduction. Specifically, foraging bumble bees utilize the resource pulses that are commonplace in modern agricultural landscapes - foraging for less time, and more frequently to exploit resources when they are available, regardless of the context of the surrounding landscape. I also found that colonies of B. impatiens grow faster, and often gain more mass when food resources are continuously available, as contrasted with when resources are only available as short, but comparatively large pulses. However, the number of reproductive individuals produced by colonies is identical regardless of the temporal presentation of food. This result was consistent in both laboratory queenless microcolonies and free-foraging, queen-right field colonies. In addition, I explored the methods commonly used to estimate floral resource abundance in foraging landscapes, and compared them in their ability to both accurately describe actual floral abundance, as well as their capacity to predict bumble bee abundance from a commonly used survey method. I found that the ability of land cover, expert opinion, and empirical methods for floral resource estimation to predict bumble bee abundance was largely similar. However, estimates of floral abundance varied greatly - especially between expert opinion and empirical estimates. Lastly, I examined trends in historical agricultural intensification metrics and their relationship to changes in bumble bee relative abundance and community composition. Here, I found that metrics of increasing agricultural intensity are clearly associated with the decline of a 40% of bumble bee species in the US Midwest. Additionally, I document several species increasing in relative abundance that positively associate with agricultural intensity, suggesting our agricultural practices have inadvertently selected winners and losers in the bumble bee community over the last century. The research herein enhances our understanding of how the availability of floral resources over time influence bumble bee behavior, colony growth and reproduction, abundance, and historical population trends. While focusing largely on Bombus impatiens, the range of organismal scales covered in this dissertation, from behavior to populations and communities, provides a framework to evaluate the response of less common species to spatiotemporal resource availability. Applications of this work range from understanding how landscape changes in floral abundance might affect bumble bee species persistence, to the large-scale changes in agricultural practices needed to stem further loss of bumble bee species.
Author: Robert John Gegear
Publisher: National Library of Canada = Bibliothèque nationale du Canada
ISBN:
Category : Bumblebees
Languages : en
Pages : 146
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The results of the three series of experiments suggest that variation in floral traits plays an integral role in the foraging decisions made by pollinators. These results are discussed in relation to pollinator cognitive abilities, floral evolution, and plant speciation and community structure.
Author: Ashley Moak
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Pesticides are chemicals that are used to control insect pests, weeds, and disease-causing microbes (bacteria, fungicides), in a wide variety of settings, from home gardens to agricultural systems. The use of pesticides -- in particular the neonicotinoid class of insecticides - has been implicated as a primary driver of global pollinator declines. Pollinators have intricate foraging behaviors to efficiently collect nectar and pollen from flowering plants, and plants have also coevolved with pollinators to create a mutually beneficial relationship. However, neonicotinoids act on the insect nervous system and thus may interfere with this complex relationship. Of the neonicotinoid class of pesticides, imidacloprid is the most widely used, including in the production and management of varieties of ornamental plants marketed specifically for pollinators. Here, I tested how exposure to field-realistic levels of imidacloprid influenced bumble bee (Bombus impatiens) foraging success and choice behavior to common ornamental plant cultivars. I demonstrate that foragers that consume even small levels of imidacloprid have impaired motivation to forage -- however I did not detect a significant change in plant preference for treated bees that did successfully forage. These studies demonstrate that exposure to even small levels of pesticides can influence pollinator behavior, which may reduce pollinator foraging success in field settings.
Author: Carlene McGrady
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Although recent studies suggest that native bees are likely supplying sufficient pollination services in Cucurbita agroecosystems, commercial pumpkin growers in Pennsylvania are spending thousands of dollars renting managed honey bees to insure adequate pollination. Here, we evaluate the ability of native bee populations to respond to increasing floral resources in a mass-flowering crop such as pumpkins, and the effect of temporal and spatial variables on pollination services supplied by native bees. We catalogued a surprisingly large community comprised of 37 species of native bees foraging in commercial pumpkin fields. Honey bees (Apis mellifera), Squash bees (Peponapis pruinosa) and Bumble bees (Bombus spp., primarily B. impatiens) were the most active pollinator taxa, contributing over 95% of all pollination services. We then examine the effect of distance from field edge on flower sex preferences using chi-squared tests and visitation rates using regression for the most active taxa. While visitation rates were not significantly impacted by distance from field edge, A. mellifera and Bombus preference for female flowers decreased as distance from field edge increased. We also evaluate the effect of field size, day of year and floral density on visitation rates using regression. Bombus visitation rates decreased as field size increased. Both A. mellifera and Bombus spp. visitation rates exhibited a curvilinear response as the growing season progressed and both responded positively to increasing floral density. We synthesized existing literature to estimate minimum pollination thresholds per taxa and calculated that A. mellifera, Bombus and P. pruinosa were each providing 10x, 12.75x and 1.8x the necessary pollination services, respectively. The relationship between visitation rates and pumpkin yield metrics were examined with principal components and correlation analysis for each year separately. Bombus spp. visitation rates positively influenced seed set and pumpkin weight in some years. P. pruinosa visitation rates positively influenced fruit per square meter in some years. A. mellifera visitation rates were never positively associated with any yield metric. This study provides strong evidence that native pollinators are sufficient for pumpkin pollination services in most settings, but managed pollinators should be considered for larger fields (> 3 - 4 ha), depending on configuration. These results have important implications for pollination management decisions and further highlights the importance of monitoring and conserving native pollinator populations. To evaluate the reliability of pollination services provided by wild B. impatiens, we estimate the abundance of Bombus impatiens colonies providing foragers for pollination services using a genetic technique known as microsatellite analysis. Microsatellite analysis is an important genetic tool with previous studies publishing guidelines for optimizing multiplexes and checklists for monitoring potentially biased loci. In this study, we proposed a standardized workflow for evaluating microsatellite loci for 5 common issues and demonstrate using the workflow to trial 14 non-species-specific loci for use in Bombus impatiens, an ecologically and economically important pollinator. We examined the DNA of > 6000 B. impatiens individuals collected from 30 sites over 4 years. We evaluated each locus for evidence of allelic drift, monomorphism, frequency of null alleles, Hardy-Weinberg disequilibrium and linkage disequilibrium. During this process, we propose a new method to visualize and account for allelic drift, which enabled us to efficiently eliminate one locus from our multi-plex, BL15. We found that BT28 was an extensively monomorphic locus. Including the monomorphic locus predictably decreased overall genetic diversity, but it did not alter patterns of genetic diversity between sites. Furthermore, monomorphic loci did not substantially impact the ability to identify genetically related foragers. Five loci exhibited isolated instances of null alleles in less than 10% of sites. One loci, BTMS0081 exhibited universal deviation from Hardy-Weinberg, but it was driven by only 2 sites. Several loci pairs were universally linked, but each linkage was driven by only 1 or 2 sites and including linked pairs had little impact on subsequent results. Implementing this systematic workflow will promote standardized methods to evaluate the extent of potentially biased loci and report the severity of the impacts on subsequent analyses. Furthermore, we can now provide a rigorously tested and thoroughly optimized multiplex of 11 microsatellite loci for use in Bombus impatiens (and potentially other Bombus species), saving financial resources and research hours for future researchers. We analyzed the genotypes generated from this optimized multiplex to test hypotheses about the abundance of B. impatiens colonies providing foragers to pumpkin fields and population genetics. Current studies assume conserving and promoting wild bumble bee colony abundance will result in increased economic and ecological benefits in the form of stable or increased pollination services, but the relationship between colony abundance and pollination services is understudied, particularly in agroecosystems. Bombus impatiens, the common eastern bumble bee, is an important pollinator in the eastern United States with recent studies proposing that the agriculture industry integrate these native bees into their pollination management strategies. However, studies regarding B. impatiens population abundance and genetic status are limited.We used microsatellite analysis and statistical models to estimate the number of B. impatiens colonies providing foragers to 30 commercial pumpkin fields in Pennsylvania and found foragers from 543.7 21.7 SE (range of 291 to 891) colonies per field. Average colony abundance per field was not affected by year (n = 4), or geographic region (n=3), indicating a temporally and spatially stable population of native pollinators. We used our large sample size to evaluate the influence of low levels of polygamy on estimating colony abundance, and showed that monogamy is a reasonable and conservative assumption for estimating colony abundance of B. impatiens. We tested for evidence of genetic differentiation using G-statistics and analysis of molecular variance and evaluated genetic diversity using expected heterozygosity and allelic richness. We confirmed previous assumptions that B. impatiens is a single, panmictic population throughout our study region of 5,000 square km and is characterized by relatively high genetic diversity, indicating a genetically resilient population with the potential to respond to selective pressures in the future. We also measured Bombus visitation rates to pumpkin flowers in a subset of 24 fields and found 0.3 0.05SE bee visits per flower per 45secons. We examined the relationship between colony abundance on a per field and per hectare basis, against visitation rates as a metric of the ecosystem service of pollination. We found that colony abundance per hectare accounted for 23% of the variation in visitation rates, indicating that wild bumble bee colony abundance, mediated by field size, positively impacts pollination services in agroecosystems. We use these relationships to discuss the influence of a mass flowering crop on colony-level abundances of a wild, native, eusocial species.
Author: Emma Thompson
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Flowers, the sole natural source of pollen and nectar for bees, present many similar features, in colour, shape, size and scent, which facilitate pollinator attraction. This similarity among stimuli requires perception of commonality but also a capacity for differentiation between similar but different stimuli. While many flowers of a similar type will elicit approach and foraging, failure to access resources on any individual flower in an array (e.g. due to depletion) will not necessarily generalize and deter further foraging. Such conditions demand that bees respond to both the similarity and differences among stimuli which may share many common features but differ individually in available resources. Two questions are raised by this challenge and will herein be addressed: how do bees perceive and respond to 'similar but different' stimuli? And, how do bees use such cues to find rewarding flowers? Picture-object correspondence has not been previously specifically studied in invertebrates. The correspondence between picture-cue and object stimuli may offer a unique opportunity to trigger memory for corresponding targets while still retaining an important distinction between unrewarding cue and rewarding targets. Perception of pictures is not always perceived by animals as either the same as or equivalent to the intended subject. According to Fagot et al. (2000) the perceived relationship may result in confusion, independence or equivalence and is dependent upon experience. The objectives of this thesis are twofold: first, determine how bumblebees (Bombus impatiens) perceive the relationship between objects and corresponding pictures and secondly, to determine whether or not bees may be able to attend to and use pictures as cues while foraging. The correspondence of picture and object by bees was evaluated with four experiments of preference: (1) learned differentiation; spontaneous association to (2) colour, and (3) achromatic, impoverished images; and (4) learned picture cue use. Firstly, results show that bees do not confuse an object with a corresponding picture but nevertheless do perceive a relationship between them if colour cues are retained. Altered, achromatic images were not consistently treated as corresponding to coloured objects. Secondly, bees can learn to use a picture cue in a delayed matching foraging task. Results further suggest a role of three contributing factors in bumblebee picture cue use: (i) conditions of high inconsistency as to which target will be rewarding; (ii) stable target locations; and (iii) individual foraging experience. It appears that bumblebees can learn to use cues, in a delayed matching task, when the location of the corresponding target is known and stable, the individual bee has acquired some experience in successful foraging, and reward is otherwise unpredictable without the use of the cue. Bees may disregard secondary cues as noise under conditions of high target predictability whereby floral constancy or target perseveration may be most efficient, but attend to and learn such cues as signals if target reward is highly unpredictable. The conditions for this sensitivity may coincide with naturally occurring floral cycles.
Author: Dana L. Church
Publisher:
ISBN:
Category : Bumblebees
Languages : en
Pages : 260
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Author:
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Category :
Languages : en
Pages :
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Author: Jessica Hagbery
Publisher:
ISBN: 9781124720661
Category :
Languages : en
Pages : 39
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Foraging specialization plays an important role in the ability of social Hymenoptera to efficiently allocate labor and adapt to environmental changes. However, relatively little is known about whether bumble bees, important social pollinators, can flexibly allocate their foraging. I removed pollen specialists at different stages in the life of a Bombus impatiens colony and recorded the pollen and nectar foraging of every forager on each foraging trip over the lifetimes of five established colonies. Adult bumble bee foragers were defined as pollen specialists (>̲90% of all foraging visits on pollen), nectar specialists (>̲90% of all foraging visits on nectar) or generalists (all other foragers). The removal of pollen specialists at early and late phases in colony life led to increased pollen foraging (36% and 14% increase, respectively) by generalist foragers. After pollen specialists were reintroduced, generalists decreased pollen foraging to prior levels. A uniform, proportional extraction of all forager types had no effect on the foraging of generalists remaining in the colony. Thus, the specific removal of pollen specialists caused the foraging compensation by generalists. This shows the importance of pollen specialists and the colony's ability to reallocate their foraging labor in response to pollen foraging labor shortages.
Author: Anne Shen
Publisher:
ISBN:
Category : Bumblebees
Languages : en
Pages : 0
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As increasing land use by humans reduces bumblebee foraging grounds, colonies are increasingly at risk of exposure to nutritional stress, which can severely impact their ability to rear high-quality workers. To determine the effects of adult size (which is directly controlled by larval nutrition) on foraging in bumblebees (Bombus impatiens), individual workers were observed foraging on both simple and complex arrays of artificial flowers. Foraging performance was determined for individuals of varying sizes as they used a simple array with one flower color and concentration of sucrose solution. Those workers who used it frequently were presented with a complex array that contained flowers of five colors, each paired with a different sucrose reward. Larger workers visited the simple array at higher rates and were more likely to become eligible for testing with the complex array than smaller workers. Larger workers also exhibited greater foraging flexibility than smaller workers, who were more likely to become trapped in innate color preferences rather than visiting more rewarding flowers. These results extend previous findings regarding the effect of size on foraging ability, suggesting that nutritional stress may be perpetuated in persistently pollen-stressed colonies, making good nutrition a key factor in bumblebee health and productivity.
