The relationship between population size,amount of brood,and individual foraging behaviour in the honey bee,Apis mellifera L.

This study experimentally examines the relationship between colony state and the behaviour of individual pollen and nectar foragers in the honey bee, Apis mellifera L. In the first experiment we test the prediction that individual pollen foragers from colonies with higher brood quantities should exhibit a greater work effort for pollen resources than individual pollen foragers from colonies with low brood quantities. Eight colonies were assigned into two treatment groups; HIGH brood colonies were manipulated to contain 9600±480 cm² brood area; LOW brood colonies were manipulated to contain 1600±80 cm² brood area. We measured colony brood levels over the course of the experiment and collected individual pollen loads from returning pollen foragers. We found that, while colonies remained significantly different in brood levels, individual pollen foragers from HIGH brood colonies collected larger loads than individuals from LOW brood colonies. In the second experiment we investigated the influence of colony size on the behaviour of individual nectar foragers. We assigned eight colonies to two treatment groups; LARGE colonies were manipulated to contain 35000±1700 adult workers with 3500±175 cm² brood area, and SMALL colonies were manipulated to contain 10000±500 adult workers with 1000±50 cm² brood area. We observed foraging trips of individually marked workers and found that individuals from LARGE colonies made longer foraging trips than those from SMALL colonies (LARGE: 1666.7±126.4 seconds, SMALL: 1210.8±157.6 seconds), and collected larter nectar loads (LARGE: 19.2±1.0 l, SMALL: 14.6±0.8 l). These results indicate that individual nectar foragers from LARGE colonies tend to work harder than individuals from SMALL colonies. Both experiments indicate that the values of nectar and pollen resources to a colony change depend on colony state, and that individual foragers modify their behaviour accordingly.     

Using the waggle dance to determine the spatial ecology of honey bees during commercial crop pollination

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Colour association influences honey bee choice between sucrose concentrations

Certain colours associated with floral food resources are more quickly learned by honey bees (Apis mellifera) than are other colours. But the impact of colour, and other floral cues, on bee choice behaviour has not yet been determined. In these experiments, colour association and sugar concentration of reward were varied to assess how they interact to affect bee choice behaviour. Thirty-five bees were individually given binary choices between blue and yellow artificial flowers that contained either the same rewards or rewards of different sucrose concentrations. Honey bee choice between sucrose concentrations was affected by colour association and this effect was greatest when absolute difference between rewards was the lowest. The honey bee's ability to maximize energetic profitability during foraging is constrained by floral cue effectiveness.     

传粉蜂在设施农业中的应用及挑战

昆虫为植物传粉是自然生态系统中的重要环节,在农业和自然生态系统的平衡与调控方面发挥着重要作用。以蜜蜂、熊蜂为代表的传粉蜂因其高效传粉及可人工饲养的特点,已成为设施农业中的优势传粉昆虫。本文总结了传粉蜂在设施农业中的应用现状,并从温湿度、农药、重金属等非生物因素和蜂种、病原生物、天敌、蜜源植物等生物因素两大方面讨论了传粉蜂在应用中面临的诸多挑战。此外,本文初步探讨了植物病虫害对传粉昆虫传粉效率的影响,并对传粉蜂未来的研究和应用方向进行了展望,旨在推动实现传粉蜂在农业中的高效授粉功能,为农产品增产增效服务。     

Economic gain,stability of pollination and bee diversity decrease from southern to northern Europe

Bees are in decline potentially leading to reduced pollination and hence production of insect-pollinated crops in many countries. It is however still unclear whether the consequences of pollinator shortages differ among countries with different environmental and societal conditions. Here, we calculated economic gains attributed to insect (particularly bee) pollination (EVIP) as well as their contribution to the total value of crop production (vulnerability), and analyzed their temporal trends and inter-annual variability from 1991 to 2009 for each country of the European Union (EU). To understand which factors drive country-specific differences in pollinator dependency and stability of insect-dependent crop yields, we further asked whether EVIP, vulnerability and stability of yields were influenced by a country's climate, the number of wild bee species and/or managed honeybee hives per country, and (agricultural) gross domestic product (GDP).Across Europe, crop pollination by insects accounted for 14.6 [±3.3] billion EUR annually (EVIP), which equaled 12 (±0.8)% of the total economic value of annual crop production. Gains strongly varied among countries. Both EVIP and vulnerability increased (and the inter-annual variation of vulnerability decreased) significantly from the colder northern to the warmer Mediterranean EU countries, in parallel with increases in the number of wild bee species. Across years, economic importance of pollination increased in all but three EU countries. Apples were the most important insect-pollinated crop in the EU, accounting for 16% of the EU's total EVIP. Our results show that whereas dependency on insect pollination increased from the colder north to the warmer south, variation in economic gain from insect pollination decreased, indicating that Mediterranean countries had more stable yields of pollinator-dependent crops across years and thus more reliable gains from pollination services.     

Small wild bee abundance declines with distance into strawberry crops regardless of field margin habitat

The preservation of pollinator habitat on croplands in the form of hedgerows, wildflower strips, and natural and semi-natural areas can help maintain and enhance wild bee populations in agricultural landscapes. However, there have been few comparisons of the effectiveness of different types of field-margin pollinator habitat in maintaining bee diversity and pollination of the focal crops. We compared wild bee abundance, species richness and community composition between strawberry crops bordered by hedgerows, and those bordered by larger expanses of natural land (forests). Strawberry is an ideal crop in which to investigate pollinator export from field margins as the rows are covered with straw, which reduces habitat for ground-nesting bees within the crop; thus, most wild pollinators need to enter the crop from the margins. We sampled bees in six strawberry fields with hedgerow margins and six strawberry fields with forested margins of at least 200 m in length, using a paired design. We examined strawberry pollen deposition at regular intervals into the fields, and the magnitude of pollinator export from the field margins towards the centre of the crops. We found that bees as a group were no more species-rich or abundant in crops bordered by forests than in crops bordered by hedgerows, although large-bodied bees were more abundant in the former than the latter. Regardless of field-margin type, we found that small wild bee abundance declined significantly from the edge to the centre of the crop, but honey bee (Apis mellifera L.) and large-bodied bee abundance did not. Strawberry pollen deposition also did not decline with distance into the crop. Although previous work indicates that small wild bees are more effective (yield-increasing) pollinators of strawberry on a per-visit basis, their limited foraging ranges suggest they may only pollinate areas near the crop margins, given typical field sizes in our area.     

Bumble bee olfactory information flow and contact-based foraging activation

Nestmate foraging activation and interspecific variation in foraging activation is poorly understood in bumble bees, as compared to honey bees and stingless bees. We therefore investigated olfactory information flow and foraging activation in the New World bumble bee species, Bombus impatiens. We (1) tested the ability of foragers to associate forager-deposited odor marks with rewarding food, (2) determined whether potential foragers will seek out the food odor brought back by a successful forager, and (3) examined the role of intranidal tactile contacts in foraging activation. Bees learned to associate forager-deposited odor marks with rewarding food. They were significantly more attracted to an empty previously rewarding feeder presented at a random position within an array of eight previously non-rewarding feeders. However, foragers did not exhibit overall odor specificity for short-term, daily floral shifts. For two out of three tested scents, activated foragers did not significantly prefer the feeder providing the same scent as that brought back by a successful forager. Finally, bees contacted by the successful forager inside the nest were significantly more likely to leave the nest to forage (38.6% increase in attempts to feed from empty feeders) than were non-contacted bees. This is the first demonstration that tactile contact, a hypothesized evolutionary basal communication mechanism in the social corbiculate bees, is involved in bumble bee foraging activation. Received 4 September 2007; revised 30 May 2008; accepted 15 July 2008.     

Bumble bee (Hymenoptera: Apidae) activity and pollination levels in commercial tomato greenhouses

Commercial greenhouse studies were conducted to assess levels of pollination of tomato (Lycopersicon esculentum Mill.) flowers in relation to bumble bee (Bombus impatiens Cresson) colony activity and colony densities. For the assessment of pollination levels of tomato flowers, five categories were defined based on bruising levels caused by bumble bee pollination. Colony activity was measured as bee trips per ha/d using electric powered photodiode monitors inserted into the hive entrance. Levels of pollination were positively correlated with bee activity levels, up to a mean of approximately 400 pollen grains per stigma per day, after which greater activity did not result in further increases in daily pollination levels. Densities of colonies in the commercial greenhouses studied ranged from 7.6 to 19.8 colonies per hectare with a mean of 11.6 +/- 0.9. We found that an average activity of 2,000 bee trips per hectare per day was more than adequate to ensure sufficient pollination, and that this level of activity could be achieved with 7-15 colonies per hectare, depending on greenhouse conditions. Greenhouses requiring >15 colonies per hectare to achieve this level of pollination may be able to increase bee activity through alteration of greenhouse conditions. Across 50-m rows of tomato plants, levels of pollination decreased with increasing distance from bee colonies, suggesting that colonies should be evenly distributed throughout the greenhouses.     

Effects of pollen species composition on the foraging behaviour and offspring performance of the mason bee Osmia bicornis (L.)

The effects of floral species composition on offspring performance of solitary bees are rarely studied under conditions where foraging behaviour of mothers is allowed to play a role. In a semi-field experiment, we restricted foraging choices of the polylectic mason bee Osmia bicornis L. to flower species belonging to plant families presumably used to different extent: Borago officinalis L. (Boraginaceae), Centaurea cyanus L. (Asteraceae) and Brassica napus L. (Brassicaceae). We quantified the foraging behaviour and brood cell production by mother bees, and compared the quality of offspring in pure and mixed flower species stands. Offspring survival in pure stands was expected to reflect the mothers’ foraging preferences in the mixed stand. Pure stands of B. napus supported highest offspring survival, body mass and fraction of females produced. Offspring survival on C. cyanus and B. officinalis was very low. Larval mortality occurred earlier in brood cells provided with B. officinalis pollen than in brood cells provided with C. cyanus pollen suggesting different effects of pollen quality on early larval and later development. The time spent on different foraging activities correlated with lifetime reproductive output. However, in mixed stands, the proportion of time the bees were foraging on the different flower species did not differ significantly. Foraging behaviour may therefore not generally be a good proxy for the quality of floral resources for offspring production. Our results suggest that resources collected from one plant species may influence the usefulness of resources from another plant species. Bees may therefore overcome potentially deleterious effects of the suboptimal resources by mixing low- and high-quality resources. This may help generalist bees, such as O. bicornis, to cope with an unpredictable environment.     

Integrated crop pollination to buffer spatial and temporal variability in pollinator activity

Insect pollination improves the yield and quality of many crops, yet there is increasing evidence of insufficient insect pollinators limiting crop production. Effective Integrated Crop Pollination (ICP) involves adaptable, targeted and cost-effective management of crop pollination and encourages the use of both wild and managed pollinators where appropriate. In this study we investigate how the addition of honeybee hives affects the community of insects visiting oilseed rape, and if hive number and location affect pollinator foraging and oilseed rape pollination in order to provide evidence for effective ICP. We found that introducing hives increased overall flower visitor numbers and altered the pollinator community, which became dominated by honeybees. Furthermore a greater number of hives did not increase bee numbers significantly but did result in honeybees foraging further into fields. The timing of surveys and proximity to the field edge influenced different pollinators in different ways and represents an example of spatial and temporal complementarity. For example dipteran flower visitor numbers declined away from the field edge whereas honeybees peaked at intermediate distances into the field. Furthermore, no significant effects of survey round on wild bees overall was observed but honeybee numbers were relatively lower during peak flowering and dipteran abundance was greater in later survey rounds. Thus combining diverse wild pollinators and managed species for crop pollination buffers spatial and temporal variation in flower visitation. However we found no effect of insect pollination on seed set or yield of oilseed rape in our trial, highlighting the critical need to understand crop demand for insect pollination before investments are made in managing pollination services.     

Windows of opportunity and the temporal structuring of foraging activity in a desert solitary bee

1. Females of the desert solitary bee Anthophora pauperata collect nectar and pollen almost exclusively from Alkanna orientalis (Boraginaceae). The bee and plant are found together in the early spring, living in the bottom of steep-sided wadis (dry river valleys) at an altitude of 1500 m in Egyptian Sinai. 2. Female A. pauperata showed clear morning and afternoon peaks in foraging activity, separated by a 2–3 h midday period spent in their underground nests. This study analyses the following in order to identify the factors structuring this daily pattern: thermal aspects of the bee and its environment, temporal patterns of resource provision by the plant, and female nectar and pollen foraging behaviour. 3. Although A. pauperata can generate substantial heat endothermically, morning and evening ambient temperatures well below 10 °C defined a thermal window within which foraging occurred. Maximum air temperatures were moderate (25–30 °C), and examination of the physiology and behaviour of A. pauperata suggests that the midday reduction in flight activity was not due to thermal constraints. 4. Alkanna orientalis produces protandrous hermaphroditic flowers. Female A. pauperata collected pollen from male-phase flowers and harvested nectar preferentially from female-phase flowers. Although the nectar standing crop was relatively constant throughout the day, pollen availability peaked strongly in the early afternoon. 5. Female A. pauperata visited young male-phase flowers as soon as they opened, generating an early afternoon peak in pollen foraging activity and depleting the pollen standing crop rapidly. A morning peak in pollen foraging occurred when females gleaned remnant pollen from flowers that had opened the previous day. Pollen availability in the morning was far lower than in the early afternoon, and the time taken to collect a full pollen load in the morning was significantly longer. Collection of pollen in the morning despite very low resource availability suggests that pollen may be a limiting resource for A. pauperata. 6. In contrast to many existing examples of bimodal activity patterns in highly endothermic bees, the bimodal activity patterns of female A. pauperata appear to be driven not by thermal considerations but by daily patterns of pollen release from its principal food source.     

Pollination efficiency and foraging behaviour of honey bees and non‐Apis bees to sweet cherry

1. Crop pollination generally increases with pollinator diversity and wild pollinator visitation. To optimize crop pollination, it is necessary to investigate the pollination contribution of different pollinator species. In the present study, we examined this contribution of honey bees and non‐Apis bees (bumble bees, mason bees and other solitary bees) in sweet cherry.
2. We assessed the pollination efficiency (fruit set of flowers receiving only one visit) and foraging behaviour (flower visitation rate, probability of tree change, probability of row change and contact with the stigma) of honey bees and different types of non‐Apis bees.
3. Single visit pollination efficiency on sweet cherry was higher for both mason bees and solitary bees compared with bumble bees and honey bees. The different measures of foraging behaviour were variable among non‐Apis bees and honey bees. Adding to their high single visit efficiency, mason bees also visited significantly more flower per minute, and they had a high probability of tree change and a high probability to contact the stigma.
4. The results of the present study highlight the higher pollination performance of solitary bees and especially mason bees compared with bumble bees and honey bees. Management to support species with high pollination efficiency and effective foraging behaviour will promote crop pollination.

     

Bumble bee pollen use and preference across spatial scales in human‐altered landscapes

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Honey bee (Apis mellifera) preference towards micronutrients and their impact on bee colonies

Honey bees are important pollinators and take micronutrients from different natural floral resources and turbid water to adequately meet their nutritional requirements. But the role of micronutrients for honey bee health is not well understood. Here, the present study was conducted to determine honey bees' micronutrients preference in summer and winter seasons. Also, the impact of micronutrients on foraging behaviour and brood increase was studied in different honey bee colonies. The results elucidated that honey bees exhibited a strong preference for a salt solution compared to deionized water during the summer and winter seasons. However, there was a notable switch in salt preference between seasons. Overall, honey bees showed significantly more foraging activity, more pollen collection, and increased brood area after sodium consumption compared to other minerals in the summer season. Further, pollen collection and brood area were significantly higher after the use of potassium in the winter season. Thus, the food preference of honey bees is strongly linked with the seasons and the availability of the floral resources. Our data suggested that honey bees may seek specific nutrients during variation of the seasonal conditions.     

Pollinator genetics and pollination: do honey bee colonies selected for pollen‐hoarding field better pollinators of cranberry Vaccinium macrocarpon?

1. Genetic polymorphisms of flowering plants can influence pollinator foraging but it is not known whether heritable foraging polymorphisms of pollinators influence their pollination efficacies. Honey bees Apis mellifera L. visit cranberry flowers for nectar but rarely for pollen when alternative preferred flowers grow nearby. 2. Cranberry flowers visited once by pollen‐foraging honey bees received four‐fold more stigmatic pollen than flowers visited by mere nectar‐foragers (excluding nectar thieves). Manual greenhouse pollinations with fixed numbers of pollen tetrads (0, 2, 4, 8, 16, 32) achieved maximal fruit set with just eight pollen tetrads. Pollen‐foraging honey bees yielded a calculated 63% more berries than equal numbers of non‐thieving nectar‐foragers, even though both classes of forager made stigmatic contact. 3. Colonies headed by queens of a pollen‐hoarding genotype fielded significantly more pollen‐foraging trips than standard commercial genotypes, as did hives fitted with permanently engaged pollen traps or colonies containing more larvae. Pollen‐hoarding colonies together brought back twice as many cranberry pollen loads as control colonies, which was marginally significant despite marked daily variation in the proportion of collected pollen that was cranberry. 4. Caloric supplementation of matched, paired colonies failed to enhance pollen foraging despite the meagre nectar yields of individual cranberry flowers. 5. Heritable behavioural polymorphisms of the honey bee, such as pollen‐hoarding, can enhance fruit and seed set by a floral host (e.g. cranberry), but only if more preferred pollen hosts are absent or rare. Otherwise, honey bees' broad polylecty, flight range, and daily idiosyncrasies in floral fidelity will obscure specific pollen‐foraging differences at a given floral host, even among paired colonies in a seemingly uniform agricultural setting.     

The challenge of accurately documenting bee species richness in agroecosystems: bee diversity in eastern apple orchards

Bees are important pollinators of agricultural crops, and bee diversity has been shown to be closely associated with pollination, a valuable ecosystem service. Higher functional diversity and species richness of bees have been shown to lead to higher crop yield. Bees simultaneously represent a mega‐diverse taxon that is extremely challenging to sample thoroughly and an important group to understand because of pollination services. We sampled bees visiting apple blossoms in 28 orchards over 6 years. We used species rarefaction analyses to test for the completeness of sampling and the relationship between species richness and sampling effort, orchard size, and percent agriculture in the surrounding landscape. We performed more than 190 h of sampling, collecting 11,219 specimens representing 104 species. Despite the sampling intensity, we captured <75% of expected species richness at more than half of the sites. For most of these, the variation in bee community composition between years was greater than among sites. Species richness was influenced by percent agriculture, orchard size, and sampling effort, but we found no factors explaining the difference between observed and expected species richness. Competition between honeybees and wild bees did not appear to be a factor, as we found no correlation between honeybee and wild bee abundance. Our study shows that the pollinator fauna of agroecosystems can be diverse and challenging to thoroughly sample. We demonstrate that there is high temporal variation in community composition and that sites vary widely in the sampling effort required to fully describe their diversity. In order to maximize pollination services provided by wild bee species, we must first accurately estimate species richness. For researchers interested in providing this estimate, we recommend multiyear studies and rarefaction analyses to quantify the gap between observed and expected species richness.     

Evolutionary transition between bee pollination and hummingbird pollination in Salvia: Comparing means,variances and covariances of corolla traits

Covariation among traits can modify the evolutionary trajectory of complex structures. This process is thought to operate at a microevolutionary scale, but its long‐term effects remain controversial because trait covariation can itself evolve. Flower morphology, and particularly floral trait (co)variation, has been envisioned as the product of pollinator‐mediated selection. Available evidence suggests that major changes in pollinator assemblages may affect the joint expression of floral traits and their phenotypic integration. We expect species within a monophyletic lineage sharing the same pollinator type will show not only similarity in trait means but also similar phenotypic variance‐covariance structures. Here, we tested this expectation using eighteen Salvia species pollinated either by bees or by hummingbirds. Our findings indicated a nonsignificant multivariate phylogenetic signal and a decoupling between means and variance‐covariance phenotypic matrices of floral traits during the evolution to hummingbird pollination. Mean trait value analyses revealed significant differences between bee‐ and hummingbird‐pollinated Salvia species although fewer differences were detected in the covariance structure between groups. Variance‐covariance matrices were much more similar among bee‐ than hummingbird‐pollinated species. This pattern is consistent with the expectation that, unlike hummingbirds, bees physically manipulate the flower, presumably exerting stronger selection pressures favouring morphological convergence among species. Overall, we conclude that the evolution of hummingbird pollination proceeded through different independent transitions. Thus, although the evolution of hummingbird pollination led to a new phenotypic optimum, the process involved the diversification of the covariance structure.     

不同蜂在温室草莓园的访花行为和传粉生态学比较

应用意大利蜜蜂、本土小峰熊蜂和引自欧洲的地熊蜂3种蜂在北京为温室草莓传粉,对其传粉行为和生态特性进行研究。结果表明:意大利蜜蜂的出巢温度、工作起点温度、平均单花停留时间和访花间隔时间均显著高于小峰熊蜂和地熊蜂(P<0.01),而这些行为在2种熊蜂之间差异不显著(P>0.05);3种蜂携带花粉回巢的比例依次为意大利蜜蜂>小峰熊蜂>地熊蜂,而其携带的花粉活性依次为意大利蜜蜂>小峰熊蜂=地熊蜂;2种熊蜂开始活动的时间比意大利蜜蜂早,日活动时间比意大利蜜蜂长;地熊蜂在一天中的活动频率最高(P<0.01);经3种蜂授粉的草莓果实营养品质差异不显著(P>0.05),与对照相比也无差异,而经过3种蜂授粉的草莓果实畸形率降低、单果质量增大;经2种熊蜂授粉的草莓果实畸形率低于意大利蜜蜂(P<0.05)。本土小峰熊蜂能够有效替代意大利蜜蜂或地熊蜂为温室草莓授粉。