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Honey bees (Linnaeus, Hymenoptera: Apidae) are widely used as commercial pollinators and commonly forage in agricultural and urban landscapes containing neonicotinoid-treated plants. Previous research has demonstrated that honey bees display adverse behavioral and cognitive effects after treatment with sublethal doses of neonicotinoids. In laboratory studies, honey bees simultaneously increase their proportional intake of neonicotinoid-treated solutions and decrease their total solution consumption to some concentrations of certain neonicotinoids. These findings suggest that neonicotinoids might elicit a suboptimal response in honey bees, in which they forage preferentially on foods containing pesticides, effectively increasing their exposure, while also decreasing their total food intake; however, behavioral responses in semifield and field conditions are less understood. Here we conducted a feeder experiment with freely flying bees to determine the effects of a sublethal, field-realistic concentration of imidacloprid (IMD) on the foraging and recruitment behaviors of honey bees visiting either a control feeder containing a sucrose solution or a treatment feeder containing the same sucrose solution with IMD. We report that IMD-treated honey bees foraged less frequently (–28%) and persistently (–66%) than control foragers. Recruitment behaviors (dance frequency and dance propensity) also decreased with IMD, but nonsignificantly. Our results suggest that neonicotinoids inhibit honey bee foraging, which could potentially decrease food intake and adversely affect colony health. [ABSTRACT FROM AUTHOR]

Noisy animal communication presents a unique challenge for biologists interpreting a produced signal precisely and accurately. One past approach has been to reduce noise. Lately, with the advance of quantitative tools, an alternative is to use the noise to improve model predictions. Here we take the latter approach to improve our ability to recover honey bee (Apis mellifera spp.) foraging locations, in particular the distance at which they forage, from observed waggle dance communications, which encode the vector from the hive to the forage. This vector gives both the distance from the hive to the forage, which is encoded in dance duration, and the direction from the hive to the forage, which is encoded in the angle that the bee makes while dancing. We analysed the waggle dances from individually marked honey bees (N = 859 dances from 85 bees from 3 hives) that foraged at multiple known locations to determine a distance-to-duration calibration. Next we compared this calibration to a previously published calibration, which demonstrated that while their slopes were similar (P = 0.82), their intercepts differed (P < 0.001); however, the individual variation, or noise, between bees was so high that this difference was rendered biologically irrelevant. We then collated our data with all published calibration studies to generate a universal calibration that incorporates the interindividual and interstudy differences. Lastly, we verified that the universal calibration performed as well as a landscape/subspecies-specific calibration, first with a hold-out sample of waggle dances (N = 84) (performance comparison: P = 0.36) and second with a linear discriminant analysis, which failed to assign dances to their originating population. Both results confirm that the universal calibration may be used, irrespective of landscape or subspecies. Therefore, by allowing noise to be part of our analysis, the usability of our calibration is broadened for use in future settings. Highlights • We describe a site-specific distance calibration for the honey bee waggle dance. • This calibration significantly differs from a previously published calibration. • We use calibration variation to create a universal calibration for dance decoding. • The universal calibration performs no worse than a site-specific calibration. • Eavesdropping scientists may use the universal calibration in future studies. [ABSTRACT FROM AUTHOR]

Waggle dancing bees provide nestmates with spatial information about high quality resources. Surprisingly, attempts to quantify the benefits of this encoded spatial information have failed to find positive effects on colony foraging success under many ecological circumstances. Experimental designs have often involved measuring the foraging success of colonies that were repeatedly switched between oriented dances versus disoriented dances (i.e. communicating vectors versus not communicating vectors). However, if recruited bees continue to visit profitable food sources for more than one day, this procedure would lead to confounded results because of the long-term effects of successful recruitment events. Using agent-based simulations, we found that spatial information was beneficial in almost all ecological situations. Contrary to common belief, the benefits of recruitment increased with environmental stability because benefits can accumulate over time to outweigh the short-term costs of recruitment. Furthermore, we found that in simulations mimicking previous experiments, the benefits of communication were considerably underestimated (at low food density) or not detected at all (at medium and high densities). Our results suggest that the benefits of waggle dance communication are currently underestimated and that different experimental designs, which account for potential long-term benefits, are needed to measure empirically how spatial information affects colony foraging success. [ABSTRACT FROM AUTHOR]

Summary: Since 1994, more than €41 billion has been spent in the European Union on agri-environment schemes (AESs), which aim to mitigate the effects of anthropomorphic landscape changes via financial incentives for land managers to encourage environmentally friendly practices [1–6]. Surprisingly, given the substantial price tag and mandatory EU member participation [2], there is either a lack of [1] or mixed [1, 2, 7] evidence-based support for the schemes. One novel source of data to evaluate AESs may be provided by an organism that itself may benefit from them. Honeybees (Apis mellifera), important pollinators for crops and wildflowers [8, 9], are declining in parts of the world from many factors, including loss of available forage from agricultural intensification [10–13]. We analyzed landscape-level honeybee foraging ecology patterns over two years by decoding 5,484 waggle dances from bees located in the center of a mixed, urban-rural 94 km2 area, including lands under government-funded AESs. The waggle dance, a unique behavior performed by successful foragers, communicates to nestmates the most profitable foraging locations [14–16]. After correcting for distance, dances demonstrate that honeybees possess a significant preference for rural land managed under UK Higher Level AESs and a significant preference against rural land under UK Organic Entry Level AESs. Additionally, the two most visited areas contained a National and Local Nature Reserve, respectively. Our study demonstrates that honeybees, with their great foraging range and sensitive response to forage quality, can be used as bioindicators to monitor large areas and provide information relevant to better environmental management. Video Abstract: Display Omitted [Copyright &y& Elsevier]

Even as demand for their services increases, honey bees (Apis mellifera) and other pollinating insects continue to decline in Europe and North America. Honey bees face many challenges, including an issue generally affecting wildlife: landscape changes have reduced flower-rich areas. One way to help is therefore to supplement with flowers, but when would this be most beneficial? We use the waggle dance, a unique behaviour in which a successful forager communicates to nestmates the location of visited flowers, to make a 2-year survey of food availability. We “eavesdropped” on 5097 dances to track seasonal changes in foraging, as indicated by the distance to which the bees as economic foragers will recruit, over a representative rural-urban landscape. In year 3, we determined nectar sugar concentration. We found that mean foraging distance/area significantly increase from springs (493 m, 0.8 km2) to summers (2156 m, 15.2 km2), even though nectar is not better quality, before decreasing in autumns (1275 m, 5.1 km2). As bees will not forage at long distances unnecessarily, this suggests summer is the most challenging season, with bees utilizing an area 22 and 6 times greater than spring or autumn. Our study demonstrates that dancing bees as indicators can provide information relevant to helping them, and, in particular, can show the months when additional forage would be most valuable. [ABSTRACT FROM AUTHOR]

Honey bees communicate to nestmates locations of resources, including food, water, tree resin and nest sites, by making waggle dances. Dances are composed of repeated waggle runs, which encode the distance and direction vector from the hive or swarm to the resource. Distance is encoded in the duration of the waggle run, and direction is encoded in the angle of the dancer’s body relative to vertical. Glass-walled observation hives enable researchers to observe or video, and decode waggle runs. However, variation in these signals makes it impossible to determine exact locations advertised. We present a Bayesian duration to distance calibration curve using Markov Chain Monte Carlo simulations that allows us to quantify how accurately distance to a food resource can be predicted from waggle run durations within a single dance. An angular calibration shows that angular precision does not change over distance, resulting in spatial scatter proportional to distance. We demonstrate how to combine distance and direction to produce a spatial probability distribution of the resource location advertised by the dance. Finally, we show how to map honey bee foraging and discuss how our approach can be integrated with Geographic Information Systems to better understand honey bee foraging ecology. [ABSTRACT FROM AUTHOR]

Abstract: Task-partitioning is an important organisational principle in insect colonies and is thought to increase colony efficiency. In task-partitioning, tasks such as the collection of resources are divided into subtasks in which the material is passed from one worker to another. Previous models have assumed that worker–worker interactions are random, but experimental evidence suggests that receivers can have preferences to handle familiar materials. We used an agent-based simulation model to explore how non-random interactions during task-partitioning with direct transfer affect colony work efficiency. Because task-partitioning also allows receivers and donors to acquire foraging related information we analysed the effect of non-random interactions on informative interaction patterns. When receivers non-randomly rejected donors offering certain materials, donors overall experienced increased time delays, hive stay durations and a decreased number of transfer partners. However, the number of transfers was slightly increased, which can improve the acquisition and quality of information for donors. When receivers were non-randomly attracted to donors offering certain materials, donors experienced reduced transfer delays, hive stay durations and an increased number of simultaneous receivers. The number of transfers is slightly decreased. The effects of the two mechanisms “non-random rejection” and “non-random attraction” are biggest if the number of foragers and receivers is balanced. In summary, our results show that colony ergonomics are improved if receivers do not reject donors and if mechanisms exist that help receivers detect potential donors, such as learning the odour of the transferred food. Finally, our simulations suggest that non-random interactions can potentially affect the foraging patterns of colonies in changing environments. [Copyright &y& Elsevier]

Successful honey bee foragers communicate where they have found a good resource with the waggle dance, a symbolic language that encodes a distance and direction. Both of these components are repeated several times (1 to > 100) within the same dance. Additionally, both these components vary within a dance. Here we discuss some causes and consequences of intra-dance and inter-dance angular variation and advocate revisiting von Frisch and Lindauer's earlier work to gain a better understanding of honey bee foraging ecology. [ABSTRACT FROM AUTHOR]

Knowledge of foraging currencies and costs is important for understanding honeybee food collection economics and to parameterize their foraging behaviors as indicators of habitat quality, which is important in the identification of management targets in human-altered landscapes. Previous research has yielded inconsistent results regarding the relationship between honey bees and important agroecosystems, such as agricultural grasslands. Waggle dance decoding provides a method for resolving these inconsistencies by mapping and quantifying bee recruitment to agricultural grasslands using statistical methods that appropriately account for foraging distance, or cost. Here we decoded 3881 dances across two foraging years to investigate when and where honey bees forage in a mixed-use landscape in Virginia, with a particular interest in honey bee use of agricultural grasslands (pastures and haylands). We initially observe that bees recruited heavily to agricultural grasslands compared to croplands, developed lands and forests, where the percent foraging to that land type was at 30.7% (CI: 29.4–31.8%), and thus significantly higher than its representation in the landscape (c. 23%). Honey bees also recruited heavily to agricultural grasslands across months, with percent foraging ranging from 26.9% (23.5–30.1%) in August to 38.8% (31.3–46.9%) in October. However, when we examined distance-corrected foraging rates, which allowed us to compare land type attractiveness when flight cost is removed, we found that the agricultural grasslands were not more attractive than the broader landscape and were significantly less attractive than, for example, croplands. We additionally identify potential forage gaps in agricultural grasslands during June and August, while also distinguishing them as a possible source of forage in October before colony overwintering in this landscape. Furthermore, we qualitatively observe a hot spot, demonstrating high foraging interest that is composed of agricultural grasslands, developed lands, and croplands and is itself a mixed-use area. Together, these results demonstrate that honey bees utilize heterogeneous land areas and underscore the importance of statistical analyses that incorporate biological knowledge. Lastly, these data will be important in informing future management aimed at pollinators in agricultural grasslands. • We decoded waggle dances to investigate honey bee foraging in a mixed-use landscape in Virginia. • We report that honey bees recruited to agricultural grasslands throughout the foraging season across two years. • After correcting for flight distance, a relevant foraging cost, honey bees did not recruit preferentially to this land type. • Together, these results provide useful insights for agricultural grassland management aimed at honey bees. [ABSTRACT FROM AUTHOR]

Neonicotinoid insecticides used to treat the seeds of bee-attractive crops occur in trace amounts in nectar and pollen. Possible harm to bees has resulted in the European Commission imposing a precautionary two-year moratorium on the use of neonicotinoids on bee-attractive crops from 2013. Recent laboratory and semi-field studies on colony-level effects of neonicotinoids assumed exclusive or near-exclusive levels of colony foraging on a treated crop. But is this a realistic assumption? Six honey bee ( Apis mellifera ) colonies were monitored over two springs (April–May 2011/12) in two neighbouring locations (urban and rural) in and near Brighton, UK, to quantify foraging on oilseed rape, the most widespread bee-attractive crop in the UK, by decoding waggle dances and trapping pollen. The study area was representative of the UK agricultural landscape in that the percentage area cover of the blooming oilseed rape fields around the rural location was similar to the national average (3.3–3.9% vs 3.1%). The amount of foraging on oilseed rape fields, as indicated by dance decoding, was variable, but low, 0–0.02% for the urban and 2–26% for the rural location. Almost all foraging, 91–99%, was within 2 km, even though honey bees can forage at distances of over 10 km. Pollen trapping in 2012 supported the dance decoding results, with oilseed rape pollen comprising 14% of pollen pellets collected by foragers from rural and 4% from urban hives. The results of this study have implications for policy as they cast doubt on the generality of some previous studies on colony-level effects on social bees conducted in laboratory and semi-field settings. [ABSTRACT FROM AUTHOR]

Summary In pollination, plants provide food reward to pollinators who in turn enhance plant reproduction by transferring pollen, making the relationship largely cooperative; however, because the interests of plants and pollinators do not always align, there exists the potential for conflict, where it may benefit both to cheat the other [ 1, 2 ]. Plants may even resort to chemistry: caffeine, a naturally occurring, bitter-tasting, pharmacologically active secondary compound whose main purpose is to detract herbivores [ 3–6 ], is also found in lower concentrations in the nectar of some plants, even though nectar, unlike leaves, is made to be consumed by pollinators [ 5, 7, 8 ]. A recent laboratory study showed that caffeine may lead to efficient and effective foraging by aiding honeybee memory of a learned olfactory association [ 4 ], suggesting that caffeine may enhance bee reward perception. However, without field data, the wider ecological significance of caffeinated nectar remains difficult to interpret. Here we demonstrate in the field that caffeine generates significant individual- and colony-level effects in free-flying worker honeybees. Compared to a control, a sucrose solution with field-realistic doses of caffeine caused honeybees to significantly increase their foraging frequency, waggle dancing probability and frequency, and persistency and specificity to the forage location, resulting in a quadrupling of colony-level recruitment. An agent-based model also demonstrates how caffeine-enhanced foraging may reduce honey storage. Overall, caffeine causes bees to overestimate forage quality, tempting the colony into sub-optimal foraging strategies, which makes the relationship between pollinator and plant less mutualistic and more exploitative. Video Abstract [ABSTRACT FROM AUTHOR]