scholarly journals Predator crypsis enhances behaviourally mediated indirect effects on plants by altering bumblebee foraging preferences

2009 ◽  
Vol 276 (1664) ◽  
pp. 2031-2036 ◽  
Author(s):  
Thomas C. Ings ◽  
Lars Chittka
Keyword(s):  
Indirect Effects ◽  
Community Dynamics ◽  
Bombus Terrestris ◽  
Pollination Services ◽  
Pollinator Behaviour ◽  
Mediated Effects ◽  
Foraging Preferences ◽  
Entire Plant ◽  
Artificial Flowers ◽  
Crab Spiders

Predators of pollinators can influence pollination services and plant fitness via both consumptive (reducing pollinator density) and non-consumptive (altering pollinator behaviour) effects. However, a better knowledge of the mechanisms underlying behaviourally mediated indirect effects of predators is necessary to properly understand their role in community dynamics. We used the tripartite relationship between bumblebees, predatory crab spiders and flowers to ask whether behaviourally mediated effects are localized to flowers harbouring predators, or whether bees extend their avoidance to entire plant species. In a tightly controlled laboratory environment, bumblebees ( Bombus terrestris ) were exposed to a random mixture of equally rewarding yellow and white artificial flowers, but foraging on yellow flowers was very risky: bees had a 25 per cent chance of receiving a simulated predation attempt by ‘robotic’ crab spiders. As bees learnt to avoid ‘dangerous’ flowers, their foraging preferences changed and they began to visit fewer yellow flowers than expected by chance. Bees avoided spider-free yellow flowers as well as dangerous yellow flowers when spiders were more difficult to detect (the colour of yellow spiders was indistinguishable from that of yellow flowers). Therefore, this interaction between bee learning and predator crypsis could lead flower species harbouring cryptic predators to suffer from reduced reproductive success.

scholarly journals Cucurbits as a model system for crop pollination management

2019 ◽  
Vol 25 ◽  
Author(s):  
Jessica Louise Knapp ◽  
Juliet Laura Osborne
Keyword(s):  
Bombus Terrestris ◽  
Species Conservation ◽  
Floral Resources ◽  
Pollen Deposition ◽  
Pollination Services ◽  
Pollinator Visitation ◽  
Crop Species ◽  
Pollinator Behaviour ◽  
Wild Bee ◽  
Effective Pollinators

Cucurbit crops have steadily increased in production over the last 50 years, particularly in Asia where pioneering technological advancements and genetic improvements have created new hybrid varieties. Generally, cucurbits are dependent on insect-pollination for fruit set and are popular species for pollination studies. This review systematically summarises pollination research conducted in the major food genera of cucurbits: Cucurbita, Cucumis, and Citrullus, to ask: 1) what are cucurbits’ requirement for pollination and their most effective pollinators? And 2) Does pollinator management increase pollinator visitation to, and yield of, cucurbit crops? These accounts of cucurbit pollination demonstrate that wild bee species such as Bombus terrestris, B. impatiens and Eucera spp. were frequently able to fulfil the pollination requirements of multiple cucurbit species. However, pollinator behaviour, pollen deposition on stigmas, and pollinators’ contribution to yield vary between cucurbit species and study site. Nonetheless, the provision of additional floral resources at both field and farm scales may help to encourage pollination of cucurbit species whilst supporting pollinators’ nutritional requirements beyond those already provided by the cucurbit crop. Synthesising studies on cucurbits’ requirement for pollination and how pollinators vary spatially and temporally in the landscape can extend beyond cucurbit systems to inform growers and pollination ecologists of other pollinator-dependent crop species wishing to maximise pollination services, species conservation; or both.

The swift parrot Lathamus discolor (Psittacidae), social bees (Apidae), and native insects as pollinators of Eucalyptus globulus ssp. globulus (Myrtaceae)

2004 ◽  
Vol 52 (3) ◽  
pp. 371 ◽  
Author(s):  
A. B. Hingston ◽  
B. M. Potts ◽  
P. B. McQuillan
Keyword(s):  
Eucalyptus Globulus ◽  
Seed Set ◽  
Bombus Terrestris ◽  
Pollination Services ◽  
Social Bees ◽  
Single Flower ◽  
Fitness Benefits ◽  
The Cost ◽  
Effective Pollinator ◽  
Better Than

It has been argued that the production of sufficient nectar to attract bird pollinators would evolve if the fitness benefits accruing from pollination services by birds, compared with insects, outweighed the cost of increased allocation of photosynthate to nectar. This hypothesis implies that the pollination services provided by birds must be considerably better than those provided by insects with which the plant has evolved. Consistent with this, we found that the endangered native swift parrot Lathamus discolor (Shaw) was a very effective pollinator of the native tree Eucalyptus globulus Labill. in Tasmania, facilitating an average of 76% of the maximum possible seed set for open-pollinated flowers in just one visit to a flower, whereas single flower visits by native insects did not facilitate any seed production. Flowers visited once by either species of introduced social bees, the honeybee Apis mellifera L. or the bumblebee Bombus terrestris (L.), produced less than 7% of the maximum possible seed set for open-pollinated flowers. Hence, easily managed social bees appear to be poor substitutes for bird pollinators in commercial seed orchards of this tree. We propose three possible reasons why this largely bird-pollinated tree has not evolved characters that deter insects from removing nectar.

scholarly journals Higher iridescent-to-pigment optical effect in flowers facilitates learning, memory and generalization in foraging bumblebees

2017 ◽  
Vol 284 (1865) ◽  
pp. 20171097 ◽  
Author(s):  
Géraud de Premorel ◽  
Martin Giurfa ◽  
Christine Andraud ◽  
Doris Gomez
Keyword(s):  
Bombus Terrestris ◽  
Optical Measurements ◽  
Long Term Memory ◽  
Memory Retention ◽  
Optical Effect ◽  
Plant Communication ◽  
Bona Fide ◽  
Angle Of View ◽  
Artificial Flowers

Iridescence—change of colour with changes in the angle of view or of illumination—is widespread in the living world, but its functions remain poorly understood. The presence of iridescence has been suggested in flowers where diffraction gratings generate iridescent colours. Such colours have been suggested to serve plant–pollinator communication. Here we tested whether a higher iridescence relative to corolla pigmentation would facilitate discrimination, learning and retention of iridescent visual targets. We conditioned bumblebees ( Bombus terrestris ) to discriminate iridescent from non-iridescent artificial flowers and we varied iridescence detectability by varying target iridescent relative to pigment optical effect. We show that bees rewarded on targets with higher iridescent relative to pigment effect required fewer choices to complete learning, showed faster generalization to novel targets exhibiting the same iridescence-to-pigment level and had better long-term memory retention. Along with optical measurements, behavioural results thus demonstrate that bees can learn iridescence-related cues as bona fide signals for flower reward. They also suggest that floral advertising may be shaped by competition between iridescence and corolla pigmentation, a fact that has important evolutionary implications for pollinators. Optical measurements narrow down the type of cues that bees may have used for learning. Beyond pollinator–plant communication, our experiments help understanding how receivers influence the evolution of iridescence signals generated by gratings.

scholarly journals Do corporate sustainability practices enhance organizational economic performance?

2015 ◽  
Vol 7 (2/3) ◽  
pp. 184-200 ◽  
Author(s):  
Matjaž Maletic ◽  
Damjan Maletic ◽  
Jens Dahlgaard ◽  
Su Mi Dahlgaard-Park ◽  
Boštjan Gomišcek
Keyword(s):  
Organizational Development ◽  
Indirect Effects ◽  
Large Scale ◽  
Corporate Sustainability ◽  
Market Performance ◽  
Innovation Performance ◽  
Mediation Effect ◽  
Content Type ◽  
Mediated Effects ◽  
Sustainability Practices

Purpose – The purpose of this study is to clarify the relation between sustainability practices and financial and market performance, and also, the role of non-financial performance outputs in this relation. Corporate sustainability is a growing area of importance for organizational development. Managing sustainability practices successfully is an imperative in achieving competitive advantage. Design/methodology/approach – Using empirical data based on a large-scale survey among organizations in five countries (i.e. Germany, Poland, Serbia, Slovenia and Spain), this paper utilized mediation analysis to estimate and test the mediated effects in a multiple mediator model. As such, the sizes of indirect effects of sustainability practices on financial and market performance through potential mediators were estimated. Findings – The results showed that innovation performance exerts a mediation effect in the relation between sustainability practices and financial and market performance. The main conclusion is that a greater engagement in sustainability practices leads to an increased innovation performance, which in turn leads to financial and market performance. Originality/value – This paper is one of the first attempts to empirically validate sustainability exploitation and sustainability exploration practices. Besides, the analysis of the direct and indirect effects of sustainability exploration and sustainability exploitation practices on financial and market performance has not been yet addressed to a great extent.

scholarly journals Effects of sexual dimorphism on pollinator behaviour in a dioecious species

2021 ◽  
Author(s):  
Laura Moquet ◽  
Anne-Laure Jacquemart ◽  
Mathilde Dufay ◽  
Isabelle De Cauwer
Keyword(s):  
Sexual Dimorphism ◽  
Bombus Terrestris ◽  
Male Flower ◽  
Pollen Grains ◽  
Flower Size ◽  
Pollination Efficiency ◽  
Flower Number ◽  
Pollinator Behaviour ◽  
Number Of Visits ◽  
Female Flowers

Floral traits often display sexual dimorphism in insect-pollinated dioecious plant species, with male individuals typically being showier than females. While this strategy is theorized to be optimal when pollinators are abundant, it might represent a risk when they become scarce, because the disproportionately high number of visits on the most attractive sex, males, might preclude efficient pollen transfer from males to females. Here, the effect of sexual dimorphism on pollination efficiency was assessed in experimental arrays of dioecious Silene dioica that were exposed to one frequent visitor of the species, Bombus terrestris, and that differed in the magnitude of sexual dimorphism for either flower number or flower size. While flower size dimorphism did not impact pollination efficiency, we found that flower number dimorphism negatively affected the number of visits on female plants, on female flowers and on the number of female flowers visited after a male flower. However, flower number dimorphism had no effect on the number of pollen grains deposited per stigma, presumably because the decrease in the number of visits to female flowers was compensated by a higher number of pollen grains deposited per visit.

scholarly journals Conical flower cells reduce surface gloss and improve colour signal integrity for free-flying bumblebees

2021 ◽  
Vol 28 ◽  
pp. 108-126
Author(s):  
Sakkia Wilmsen ◽  
Adrian G Dyer ◽  
Klaus Lunau
Keyword(s):  
Bombus Terrestris ◽  
Incident Light ◽  
Shape Index ◽  
Floral Colour ◽  
Internal Layers ◽  
Flower Constancy ◽  
Visual Appearance ◽  
Light Surface ◽  
Colour Patterns ◽  
Artificial Flowers

Colour signals of flowers facilitate detection, spontaneous preference, discrimination and flower constancy by important bee pollinators. At short distances bees orient to floral colour patterns to find a landing platform and collect nutrition, potentially improving the plants’ reproductive success when multiple flowers are visited sequentially. In addition to pigments and backscattering structures within the petals’ internal layers, the epidermal micro-structure of the petals’ surface may also influence petal reflectance properties and thus influence overall colour patterns via optical effects. Gloss, i.e., shine caused by specular reflections of incident light from smooth surfaces, may for example alter the visual appearance of surfaces including flowers. We classify the epidermal surface properties of petals from 39 species of flowering plants from 19 families by means of a cell shape index, and measure the respective surface spectral reflectance from different angles. The spontaneous behavioural preferences of free flying bumblebees (Bombus terrestris) for surfaces with different micro-textures was then tested using specially prepared casts of selected flower petals. We specifically tested how the petal colour as function of the angle of incident light, surface structure and bee approach angle influences bumblebees’ spontaneous choices for artificial flowers. We observe that bumblebees spontaneously prefer artificial flowers with conical-papillate micro-structures under both multidirectional illumination and under spotlight conditions if approaching against the direction of spotlight, suggesting conical cells help promote constant signals by removing gloss that may confound the integrity of colour signalling. 

Dimensions and Types of Supervisory Control: Effects on Salesperson Performance and Satisfaction

1996 ◽  
Vol 60 (1) ◽  
pp. 89-105 ◽  
Author(s):  
Goutam N. Challagalla ◽  
Tasadduq A. Shervani
Keyword(s):  
Supervisory Control ◽  
Indirect Effects ◽  
Fortune 500 ◽  
Direct And Indirect Effects ◽  
Behavior Control ◽  
Salesperson Performance ◽  
Mediated Effects ◽  
Fortune 500 Companies ◽  
Independent Effects ◽  
Conceptual Work

The authors extend the conceptual work of Anderson and Oliver (1987) and Jaworski (1988) on control in three ways. First, they account for the independent effects of the reinforcement dimension of control, in addition to the information dimension traditionally studied. Second, to reflect the varied behaviors that supervisors attempt to control, they disaggregate behavior control into activity control and capability control. Third, they delineate the direct and mediated effects of control on salespeople. Their proposed framework was tested with data collected from 270 salespeople in five industrial product divisions of two Fortune 500 companies. The findings suggest that managers must carefully match controls-in-use with desired results. Overall, the results show that information and reinforcement effects vary, which suggests the need to distinguish between the information provided and the actual reinforcements administered to salespeople. They also show that activity and capability control have different effects and draw a sharp distinction between two types of behavior control. Finally, the results suggest that supervisory controls primarily have indirect effects on salesperson performance, but both direct and indirect effects on satisfaction

scholarly journals Using Temporally Resolved Floral Resource Maps to Explain Bumblebee Colony Performance in Agricultural Landscapes

Agronomy ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1993
Author(s):  
Philipp W. Eckerter ◽  
Lars Albus ◽  
Sharumathi Natarajan ◽  
Matthias Albrecht ◽  
Lolita Ammann ◽  
...  
Keyword(s):  
Agricultural Land ◽  
Bombus Terrestris ◽  
Colony Growth ◽  
Agricultural Landscapes ◽  
Wild Plants ◽  
Floral Resources ◽  
Colony Development ◽  
Pollination Services ◽  
Spatio Temporal ◽  
Floral Resource

Wild bumblebees are key pollinators of crops and wild plants that rely on the continuous availability of floral resources. A better understanding of the spatio-temporal availability and use of floral food resources may help to promote bumblebees and their pollination services in agricultural landscapes. We placed colonies of Bombus terrestris L. in 24 agricultural landscapes with various degrees of floral resource availability and assessed different parameters of colony growth and fitness. We estimated pollen availability during different periods of colony development based on detailed information of the bumblebee pollen diet and the spatial distribution of the visited plant species. Total pollen availability did not significantly explain colony growth or fitness. However, when using habitat maps, the weight gain of colonies, the number of queen cells, and colony survival decreased with increasing distance from the forest. The better explanation of bumblebee performance by forest proximity than by (plant-inferred) pollen availability indicates that other functions of forests than pollen provision were important. The conservation of forests next to agricultural land might help to sustain high populations of these important wild pollinators and enhance their crop pollination services. Combining different mapping approaches might help to further disentangle complex relationships between B. terrestris and their environment in agricultural landscapes.

scholarly journals The role of multiple reproductive barriers: strong post-pollination interactions govern cytotype isolation in a tetraploid–octoploid contact zone

2020 ◽  
Vol 126 (6) ◽  
pp. 991-1003 ◽  
Author(s):  
Mariana Castro ◽  
João Loureiro ◽  
Brian C Husband ◽  
Sílvia Castro
Keyword(s):  
Reproductive Isolation ◽  
Contact Zone ◽  
Assortative Mating ◽  
Reproductive Barriers ◽  
Pollinator Behaviour ◽  
Contact Zones ◽  
Foraging Preferences ◽  
Flowering Asynchrony ◽  
Gametic Selection

Abstract Background and Aims Polyploidy is an important contributor to sympatric speciation and assortative mating is a key mechanism driving cytotype interactions in contact zones. While strong reproductive barriers can mediate the coexistence of different cytotypes in sympatry, positive frequency-dependent mating disadvantage ultimately drives the transition to single-ploidy populations. However, comprehensive estimates of reproductive isolation among cytotypes and across multiple barriers are rare. We quantify the strength of isolation across multiple reproductive stages in a tetraploid–octoploid contact zone to understand the potential for coexistence. Methods Assortative mating due to flowering asynchrony, pollinator behaviour, morphological overlap, self-fertilization and gametic competition between tetraploid and octoploid Gladiolus communis in a contact zone in the Western Iberian Peninsula were assessed in natural and experimental populations to quantify reproductive isolation (RI) between cytotypes. Key Results Tetraploids and octoploids have a high degree of overlap in flowering time and similar floral morphology, and are visited by generalist insects without cytotype foraging preferences, resulting in weak pre-pollination RI (from 0.00 to 0.21). In contrast, post-pollination isolation resulting from gametic selection was a strong barrier to inter-cytotype mating, with ploidy composition in stigmatic pollen loads determining the levels of RI (from 0.54 to 1.00). Between-cytotype cross-incompatibility was relatively high (RI from 0.54 to 0.63) as was isolation acquired through self-pollination (RI of 0.59 in tetraploids and 0.39 in octoploids). Conclusions Total RI was high for both tetraploids (from 0.90 to 1.00) and octoploids (from 0.78 to 0.98). Such high rates of assortative mating will enable cytotype coexistence in mixed-ploidy populations by weakening the impacts of minority cytotype exclusion. This study reveals the key role of gametic selection in cytotype siring success and highlights the importance of comprehensive estimates across multiple reproductive barriers to understand cytotype interactions at contact zones.

scholarly journals Predator diversity, intraguild predation, and indirect effects drive parasite transmission

2015 ◽  
Vol 112 (10) ◽  
pp. 3008-3013 ◽  
Author(s):  
Jason R. Rohr ◽  
David J. Civitello ◽  
Patrick W. Crumrine ◽  
Neal T. Halstead ◽  
Andrew D. Miller ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Intraguild Predation ◽  
Indirect Effects ◽  
Dilution Effect ◽  
Parasite Transmission ◽  
Wildlife Diseases ◽  
Free Living ◽  
Predator Diversity ◽  
Mediated Effects ◽  
Per Capita

Humans are altering biodiversity globally and infectious diseases are on the rise; thus, there is interest in understanding how changes to biodiversity affect disease. Here, we explore how predator diversity shapes parasite transmission. In a mesocosm experiment that manipulated predator (larval dragonflies and damselflies) density and diversity, non-intraguild (non-IG) predators that only consume free-living cercariae (parasitic trematodes) reduced metacercarial infections in tadpoles, whereas intraguild (IG) predators that consume both parasites and tadpole hosts did not. This likely occurred because IG predators reduced tadpole densities and anticercarial behaviors, increasing per capita exposure rates of the surviving tadpoles (i.e., via density- and trait-mediated effects) despite the consumption of parasites. A mathematical model demonstrated that non-IG predators reduce macroparasite infections, but IG predation weakens this “dilution effect” and can even amplify parasite burdens. Consistent with the experiment and model, a wetland survey revealed that the diversity of IG predators was unrelated to metacercarial burdens in amphibians, but the diversity of non-IG predators was negatively correlated with infections. These results are strikingly similar to generalities that have emerged from the predator diversity–pest biocontrol literature, suggesting that there may be general mechanisms for pest control and that biocontrol research might inform disease management and vice versa. In summary, we identified a general trait of predators—where they fall on an IG predation continuum—that predicts their ability to reduce infections and possibly pests in general. Consequently, managing assemblages of predators represents an underused tool for the management of human and wildlife diseases and pest populations.

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