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This document is a collection of research briefs from the journal "American Entomologist." The briefs cover various topics related to insects and their behavior. One brief discusses how enhanced insect cold tolerance can be traced to the mitochondrial level. Another brief describes a new species of rove beetle that disguises itself as a termite to obtain food. A third brief explores the unique nursery pollination system between a non-photosynthesizing orchid and vinegar flies. Another brief examines the decision-making behavior of weaver ants when faced with uncertain outcomes. Additionally, there is a meta-analysis showing that non-native ants drive declines in animal community diversity, a study on the courtship signals of moths, research on the effects of neonicotinoid exposure and cold stress on bumblebees, and a study on the feeding behavior of trilobites. The document also includes a section on the ESA Science Policy Fellows' trip to Washington, DC, to engage with federal funding agencies. The text discusses the activities and meetings held during Entomology Advocacy Week 2023, organized by the Entomological Society of America (ESA). The ESA Science Policy Fellows met with various federal agencies, including the U.S. Department of Agriculture and public health programs, to discuss entomological research and its importance. The week also included webinars on federal and state advocacy, as well as letter-writing campaigns to urge congressional support for STEM workforce, agriculture innovation, and vector-borne disease [Extracted from the article]

The study of animal behavior, particularly in insects, is crucial for understanding their biological and evolutionary aspects, with wide-ranging applications in agricultural science, pest management, conservation biology, and neuroscience. Investigating cognitive characteristics, specifically aversive learning, plays a pivotal role in comprehending the success of insects. This adaptive ability enables animals to efficiently cope with the stressful factors in their environment. In this study, we investigated the aversive learning capabilities of Bombus terrestris Audax workers, crucial pollinators across diverse ecosystems. Bees were trained and tested in a flight arena using artificial flowers equipped with electric shocks to simulate conditions wherebees could associate punishment alongside food resources with available cues. The result suggested that bees possess the ability to simultaneously detect potential threats and food resources, indicating a dual aversive-appetitive memory. Furthermore, comparing groups trained with aversive (electric shock) and neutral (distilled water) stimuli showed that danger cues led to faster learning and stronger memory formation. This conditioning setup aimed to simulate real-life foraging situations, exploring bee responses when confronted with potential dangers. These findings provide insights into the survival strategies of insects in challenging environments that negatively impact bee populations. [ABSTRACT FROM AUTHOR]

Burmannia shows a set of floral traits that suggest elaborate mechanisms of animal mediated pollen transfer. These include flower coloration, septal nectaries and a long and narrow floral chamber. The stamens are synorganized with the common style restricting the entrance to the floral chamber, sometimes forming a gynostegium. Contrary to this apparent zoophilous floral syndrome, several species of Burmannia were reported to perform self-pollination via cleistogamy. Understanding of reproductive systems in Burmannia is complicated by scarcity of available results of direct observations on pollination process. Here we present data on pollination biology of B. disticha obtained during field investigations in Vietnam followed by laboratory analyses of ecologically important floral traits and the captured flower visitors. We found that the anthetic perianth is open, i.e. the flower is chasmogamous. The flowers are visited by various Diptera, Hymenoptera, Lepidoptera and Orthoptera. Of them, the bumblebees (Bombus burmensis), a bee (Coelioxys sp.) and some lepidopterans were revealed to carry pollen of B. disticha. Based on the amount of carried pollen, insect behavior during the visits and general knowledge on biology of these insect taxa, we concluded that the bumblebees act as the principal pollinators of B. disticha, whereas the lepidopterans are considered as its possible pollinators. We compared the lengths of proboscises of the captured insects to the depth of the floral chamber, and found that only the bumblebees and lepidopterans should be able to reach the nectar. Finally, we estimated the pollen-ovule ratio of B. disticha as 6.84, which is comparable to the ratio known in autogamous angiosperms. Based on its flower organization and pollination mechanism, we consider B. disticha an entomophilous and predominantly xenogamous species. Its gynostegium is likely an adaptation for pollen transfer by insects with long proboscises. At the same time, earlier investigations together with pollen-ovule ratio indicate that B. disticha possesses a labile pollination strategy, and autogamy sometimes occurs. Since Burmannia is one of the few angiosperm genera that comprise both mycoheterotrophic (achlorophyllous) and autotrophic (green) species, our study provides important evidence for reconstructions of ecological and morphological evolutionary pathways in relation to the mode of organic nutrition. [ABSTRACT FROM AUTHOR]

A key question in pollination biology is that of how pollinators identify and choose foraging patches. Several approaches have been employed for this, including field studies and large greenhouse flight chambers. Most methods used to date are limited, though, by reliance on a combination of artificial flowers, large spatial scales, or lack of spatially distinct floral patches. To address this issue, we designed and tested a y-maze flight arena and tested it using the bumblebee Bombus impatiens and canola plants. Our results indicate that the system is not biased by environmental conditions, or by an innate "handedness" of Bombus impatiens. We found that bees made all the expected patch choices when presented with soil, plants without flowers, or plants with flowers. This new method is important and useful as it allows researchers to ask questions of both plant health and insect behavior and the chamber system is modular allowing for simple changes to the setup to focus on different questions. Highlights: • Y-maze flight arena was designed to evaluate foraging behavior on intact plants. • No evidence of side preference in individual bees. • Behaviors observed in the y-maze appear to correspond to behaviors observed in other settings. [ABSTRACT FROM AUTHOR]

Summary: A new study shows that bumblebees learn socially, and this resulted in a novel behavior becoming dominant across a group. These findings highlight the opportunity going forward to use social insects to address how simple cognitive mechanisms can underpin the development of complex behavioral phenomena. [ABSTRACT FROM AUTHOR]

A recent study published in Current Biology reveals that bumble bees bite down on flowers to enhance their ability to vibrate and shake out pollen. This behavior, known as "buzz pollination," is used by about 9% of plants, including important crops like potatoes, tomatoes, and peas. The study found that when bees bit the anthers of buzz-pollinated flowers, they transmitted up to three times more vibration, resulting in more pollen collection. However, the reasons behind why bees bite and the mechanics of their head shakes remain unknown. This research highlights the complexity of insect behavior and the need for further investigation. [Extracted from the article]

Floral resources and natural enemies are considered important drivers of wild bee population dynamics, yet there is little information on how these factors, either independently or in combination, influence the demographic performance of bees. Bumble bees (Bombus spp.), ecologically important social insects, have long colony cycles lasting many weeks. Food shortfalls during the colony lifetime can result in smaller colony sizes and lower reproductive output. Conopid flies (Conopidae, Diptera) are prevalent endoparasitoids of bumble bees, often infecting high percentages of free‐flying individuals. Conopids can reduce worker life span and foraging efficiency; consequently, they may negatively affect colony success. In this study, we evaluated how seasonal variability in food resources and conopid parasitism together influence the productivity of bumble bee colonies through construction of a simulation model. In addition to simulating colony performance in relation to a defined food environment and conopid‐induced worker mortality, we evaluated how daily background mortality risk and the timing of colony initiation affected growth and reproductive outcomes of colonies, as well as the degree of influence exerted by conopids. Model parameters were largely informed by field data collected from Bombus impatiens colonies at our study site (Blandy Experimental Farm, Boyce, Virginia, USA), including data on forager risk of conopid parasitism as assessed using radio‐frequency identification (RFID) technology. In spite of the high probability of parasitism (4% per hour of flight during seasonal peak) incorporated into our model simulations, lethal parasitism by conopids generally had a modest influence on colony productivity, reducing reproductive output by 15% or less across most tested scenarios. However, conopids were more influential under very low resource conditions, reducing reproductive output by 21–28%. Inclusion of sublethal effects of conopids on foraging activity further reduced colony performance in all scenarios, but had a greater impact on colony performance under the poorest resource conditions. This work emphasizes that the importance of natural enemies to the demographic performance of bees can increase under certain environmental conditions and highlights the value of using models to consider multiple stressors that are difficult to evaluate simultaneously in field experiments. [ABSTRACT FROM AUTHOR]

Lone Bombus ignitus queens are known to start nests in small underground cavities. To examine the nestsite preference of post-hibernating queens, choice tests were carried out by providing queens with orphan colonies and empty cavities as possible nesting sites within an experimental box. Our results showed that the queens had a strong preference for takeover of an orphan colony, suggesting that nest takeover (usurpation) could occur in nature even with the presence of possible empty cavities for nesting. We compared the colony-growth process and final production of sexuals between non-takeover and takeover colonies. The increase in the number of egg cups was faster in the takeover colonies, suggesting that orphan broods elicit earlier oviposition by the usurping queen. Reproductives emerged earlier (significant for new queens) and in greater numbers (males) from takeover colonies than from non-takeover colonies. Thus, posthibernating B. ignitus queens would search for and take over small orphan colonies to increase their fitness. [ABSTRACT FROM AUTHOR]

1. Resource pulses, narrow periods of high resource availability, can elicit strong behavioural responses across diverse taxa. Mass‐flowering agricultural crops are an example of a resource pulse that insect pollinators exploit. However, the underlying mechanism behind changes in pollinator behaviour associated with mass‐flowering crops is still relatively unexplored. 2. The present study quantified the behavioural response of bumble bees, an important wild pollinator, to commercial cranberry bloom, an important mass‐flowering crop in Wisconsin, U.S.A. Over a 2‐year period, foraging trip duration was measured using radio frequency identification at 14 farms situated across landscape contexts, ranging from high to low natural area (woodland amount). Using transect surveys, floral resource abundance at a landscape scale was estimated. 3. It was found that bumble bees were highly sensitive to temporal changes in landscape‐level resource abundance associated with the onset of cranberry bloom, during which they decreased foraging trip duration by 22% and increased the number of foraging trips during bloom by 24% on average relative to the period before and after bloom. This phenomenon was consistent across colonies, individual bees, and landscape contexts, despite a higher abundance of flowers in low woodland landscapes. Bumble bee colonies growing in low‐ and high‐woodland landscapes exhibited a similar performance. 4. As mass‐flowering crops are probably a factor influencing bumble bee foraging behaviour in agricultural regions, investigations should continue into how variable resource landscapes, particularly those offering resource pulses, affect wild pollinators and the pollination services they provide. [ABSTRACT FROM AUTHOR]

Flowers act as multisensory billboards to pollinators by using a range of sensory modalities such as visual patterns and scents. Different floral organs release differing compositions and quantities of the volatiles contributing to floral scent, suggesting that scent may be patterned within flowers. Early experiments suggested that pollinators can distinguish between the scents of differing floral regions, but little is known about how these potential scent patterns might influence pollinators.We show that bumblebees can learn different spatial patterns of the same scent, and that they are better at learning to distinguish between flowers when the scent pattern corresponds to a matching visual pattern. Surprisingly, once bees have learnt the spatial arrangement of a scent pattern, they subsequently prefer to visit novel unscented flowers that have an identical arrangement of visual marks, suggesting that multimodal floral signals may exploit the mechanisms by which learnt information is stored by the bee. [ABSTRACT FROM AUTHOR]

Bumblebees are among the world's most important groups of pollinating insects in natural and agricultural ecosystems. Each spring, queen bumblebees emerge fromoverwintering and initiate newnests,which ultimately give rise to workers and newreproductives later in the season.Nest initiation and survival are thus key drivers of both bumblebee pollination services and population dynamics.We performed the first laboratory experiment with the model bumblebee species Bombus impatiens that explores how early nesting success is impacted by the effects of temporary or more sustained exposure to sublethal levels of a neonicotinoid-type insecticide (imidacloprid at 5 ppb in nectar) and by reliance on a monofloral pollen diet, two factors that have been previously implicated in bumblebee decline. We found that queens exhibited increased mortality and dramatically reduced activity levels when exposed to imidacloprid, aswell as delayed nest initiation and lower brood numbers in the nest, but partially recovered fromthese effects when they only received early, temporary exposure. The effects of pollen diet on individual queen- and colony-level responses were overshadowed by effects of the insecticide, although a monofloral pollen diet alone was sufficient to negatively impact brood production. These findings speak to the sensitivity of queen bumblebees during the nest initiation phase of the colony cycle, with implications for how queens and their young nests are uniquely impacted by exposure to threats such as pesticide exposure and foraging habitat unsuitability. [ABSTRACT FROM AUTHOR]

Critical thermal limits often determine species distributions for diverse ectotherms and have become a useful tool for understanding past and predicting future range shifts in response to changing climates. Despite recently documented population declines and range shifts of bumblebees (genus Bombus), the few measurements of thermal tolerance available for the group have relied on disparate measurement approaches. We describe a novel stereotypical behavior expressed by bumblebee individuals during entry into chill coma. This behavioral indicator of minimum critical temperature (CTmin) occurred at ambient temperatures of 3-5°C (approximately 7-9°C core temperatures) and was accompanied by a pronounced CO² pulse, indicative of loss of spiracle function. Maximum critical temperature (CTmax)was indicated by the onset ofmuscular spasms prior to entering an unresponsive state and occurred at ambient temperatures of approximately 52-55°C (42-44°C core temperatures). Measurements of CTmin and CTmax were largely unaffected by acclimation, age or feeding status, but faster ramping rates significantly increased CTmax and decreased CTmin. This high-throughput approach allows rapid measurement of critical thermal limits for large numbers of individuals, facilitating large-scale comparisonsamong bumblebee populations and species -- a key step in determining current and future effects of climate on these critical pollinators. [ABSTRACT FROM AUTHOR]

Abstract: To what extent host‐associated microbiota assembly is driven by host selection or simply by happenstance remains an open question in microbiome research. Here, we take a first step towards elucidating the relative importance of host selection on the establishing gut microbial community in an ecologically relevant organism. We presented germ‐free bumblebee, Bombus terrestris, workers from 10 colonies with a “global” microbial species pool comprised of an equal mixture of the gut microbiota of all colonies. By means of 16S amplicon sequencing, we found that overall microbiota community composition was generally shifted between pool‐exposed workers compared to workers that naturally acquired their gut microbiota, but that the specific composition of the established microbiota also depended on colony identity (e.g. genetic background). Because the microbiota is protective against parasite infection in this system, variation in the filtering of a beneficial microbial community can have important consequences for host resistance and eventual co‐evolution with parasites. [ABSTRACT FROM AUTHOR]

On leaving a significant place to which they will return, bees and wasps perform learning flights to acquire visual information to guide them back. The flights are set in different contexts, such as from their nest or a flower, which are functionally and visually different. The permanent and inconspicuous nest hole of a bumblebee worker is locatable primarily through nearby visual features, whereas a more transient flower advertises itself by its colour and shape. We compared the learning flights of bumblebees leaving their nest or a flower in an experimental situation in which the nest hole, flower and their surroundings were visually similar. Consequently, differences in learning flights could be attributed to the bee's internal state when leaving the nest or flower rather than to the visual scene. Flights at the flower were a quarter as long as those at the nest and more focused on the flower than its surroundings. Flights at the nest covered a larger area with the bees surveying a wider range of directions. For the initial third of the learning flight, bees kept within about 5 cm of the flower and nest hole, and tended to face and fixate the nest, flower and nearby visual features. The pattern of these fixations varied between nest and flower, and these differenceswere reflected in the bees' return flights to the nest and flower. Together, these findings suggest that learning flights are tuned to the bees' inherent expectations of the visual and functional properties of nests and flowers. [ABSTRACT FROM AUTHOR]

Previous reports note that males of the Japanese bumblebee Bombus ardens ardens perform nest surveillance to mate with new queens. Here, we report that males of this species also perform patrolling and scent-marking for mating. We observed that many B. ardens ardens males fly together from May to June in circular paths through a wooded area in Tokyo, Japan. The flight activity is bimodal with peaks in the morning and late afternoon. When tethered new queens were presented at a focal point, males approached, touched, or grabbed them but ignored them at a foraging site. Males performed scent-marking on tree leaves only in the early morning (05:30 to 07:30), and compounds from the labial gland of B. ardens ardens males were detected on a scent-marked leaf. Based on these findings and previous reports, we conclude that males of this species have at least two mating tactics or strategies: nest surveillance and patrolling. [ABSTRACT FROM AUTHOR]

It is essential for central place foragers, such as bumblebees, to return reliably to their nest. Bumblebees, leaving their inconspicuous nest hole for the first time need to gather and learn sufficient information about their surroundings to allow them to return to their nest at the end of their trip, instead of just flying away to forage. Therefore, we assume an intrinsic learning programme that manifests itself in the flight structure immediately after leaving the nest for the first time. In this study, we recorded and analysed the first outbound flight of individually marked naïve bumblebees in an indoor environment. We found characteristic loop-like features in the flight pattern that appear to be necessary for the bees to acquire environmental information and might be relevant for finding the nest hole after a foraging trip. Despite common features in their spatiotemporal organisation, first departure flights from the nest are characterised by a high level of variability in their loop-like flight structure across animals. Changes in turn direction of body orientation, for example, are distributed evenly across the entire area used for the flights without any systematic relationship to the nest location. By considering the common flight motifs and this variability, we came to the hypothesis that a kind of dynamic snapshot is taken during the early phase of departure flights centred at the nest location. The quality of this snapshot is hypothesised to be 'tested' during the later phases of the departure flights concerning its usefulness for local homing. [ABSTRACT FROM AUTHOR]

Foraging is an essential process for mobile animals, and its optimization serves as a foundational theory in ecology and evolution; however, drivers of foraging are rarely investigated across landscapes and seasons. Using a common bumblebee species from the western United States (Bombus vosnesenskii), we ask whether seasonal decreases in food resources prompt changes in foraging behavior and space use. We employ a unique integration of population genetic tools and spatially explicit foraging models to estimate foraging distances and rates of patch visitation for wild bumblebee colonies across three study regions and two seasons. By mapping the locations of 669 wild-caught individual foragers, we find substantial variation in colony-level foraging distances, often exhibiting a 60-fold difference within a study region. Our analysis of visitation rates indicates that foragers display a preference for destination patches with high floral cover and forage significantly farther for these patches, but only in the summer, when landscape-level resources are low. Overall, these results indicate that an increasing proportion of long-distance foraging bouts take place in the summer. Because wild bees are pollinators, their foraging dynamics are of urgent concern, given the potential impacts of global change on their movement and services. The behavioral shift toward long-distance foraging with seasonal declines in food resources suggests a novel, phenologically directed approach to landscape-level pollinator conservation and greater consideration of late-season floral resources in pollinator habitat management. [ABSTRACT FROM AUTHOR]

When foraging in their natural environment, many animals readily complement their personal knowledge with additional social information. To balance the costs and benefits of copying others, animals have to discern situations in which it is more advantageous to use social rather than personal information. Here, we used foraging bumblebees (Bombus terrestris) in a controlled laboratory setting and showed that the difficulty of a foraging task affects how the bees weight the 2 types of information. We used artificial flowers to devise easy and difficult discriminatory tasks, and tested the influence of floral and social cues on decision making. When facing an easy discrimination task, foraging bees were likely to rely on personal information and were only marginally affected by social information. By contrast, they prioritized social over personal information when flower discrimination was difficult and therefore the probability of making errors was higher. In summary, bees are able to use social and personal information to optimize foraging decisions in a flexible way. [ABSTRACT FROM AUTHOR]

Managed bees are critical for crop pollination worldwide. As the demand for pollinator-dependent crops increases, so does the use of managed bees. Concern has arisen that managed bees may have unintended negative impacts on native wild bees, which are important pollinators in both agricultural and natural ecosystems. The goal of this study was to synthesize the literature documenting the effects of managed honey bees and bumble bees on wild bees in three areas: (1) competition for floral and nesting resources, (2) indirect effects via changes in plant communities, including the spread of exotic plants and decline of native plants, and (3) transmission of pathogens. The majority of reviewed studies reported negative effects of managed bees, but trends differed across topical areas. Of studies examining competition, results were highly variable with 53% reporting negative effects on wild bees, while 28% reported no effects and 19% reported mixed effects (varying with the bee species or variables examined). Equal numbers of studies examining plant communities reported positive (36%) and negative (36%) effects, with the remainder reporting no or mixed effects. Finally, the majority of studies on pathogen transmission (70%) reported potential negative effects of managed bees on wild bees. However, most studies across all topical areas documented the potential for impact (e.g. reporting the occurrence of competition or pathogens), but did not measure direct effects on wild bee fitness, abundance, or diversity. Furthermore, we found that results varied depending on whether managed bees were in their native or non-native range; managed bees within their native range had lesser competitive effects, but potentially greater effects on wild bees via pathogen transmission. We conclude that while this field has expanded considerably in recent decades, additional research measuring direct, long-term, and population-level effects of managed bees is needed to understand their potential impact on wild bees. [ABSTRACT FROM AUTHOR]

Many insects rely on vision to find food, to return to their nest and to carefully control their flight between these two locations. The amount of information available to support these tasks is, in part, dictated by the spatial resolution and contrast sensitivity of their visual systems. Here, we investigate the absolute limits of these visual properties for visually guided position and speed control in Bombus terrestris. Our results indicate that the limit of spatial vision in the translational motion detection system of B. terrestris lies at 0.21 cycles deg with a peak contrast sensitivity of at least 33. In the perspective of earlier findings, these results indicate that bumblebees have higher contrast sensitivity in the motion detection system underlying position control than in their object discrimination system. This suggests that bumblebees, and most likely also other insects, have different visual thresholds depending on the behavioral context. [ABSTRACT FROM AUTHOR]

1. Bumblebee nests are difficult to find in sufficient numbers for well replicated studies. Counts of nest-searching queens in spring and early summer have been used as an indication of preferred nesting habitat, but this relationship has not yet been validated; high densities of nest-searching queens may indicate habitat with few nesting opportunities (meaning that queens have to spend longer looking for them). 2. From mid April 2010, queen bumblebees were counted along 20 transects in grassland and woodland habitats in central Scotland, U.K. The number of inflorescences of suitable forage plants were also estimated at each transect visit. The area surrounding each transect was searched for nests in the summer. 3. In total, 173 queen bumblebees were recorded on transects, and, of these, 149 were engaged in nest-searching. Searches subsequently revealed 33 bumblebee nests. 4. The number of nest-searching queens on transects was significantly, positively related to the number of nests subsequently found. Estimated floral abundance along the transect did not correlate with numbers of nest-searching queens or with the number of nests found, suggesting that queens do not target their searching to areas that are locally high in spring forage. 5. The data suggest that counts of nest-searching queens provide a useful positive indication of good nesting habitat, and hence where bumblebee nests are likely to be found later in the year. [ABSTRACT FROM AUTHOR]

Social insect societies are long-standing models for understanding social behaviour and evolution. Unlike other advanced biological societies (such as the multicellular body), the component parts of social insect societies can be easily deconstructed and manipulated. Recent methodological and theoretical innovations have exploited this trait to address an expanded range of biological questions. We illustrate the broadening range of biological insight coming from social insect biology with four examples. These new frontiers promote open-minded, interdisciplinary exploration of one of the richest and most complex of biological phenomena: sociality. [ABSTRACT FROM AUTHOR]

The bumblebee ( Bombus terrestris) has become a common model animal in the study of various aspects of vision and visually guided behavior. Although the bumblebee visual system has been studied to some extent, little is known about the functional role of the first visual neuropil, the lamina. In this work, we provide an anatomical and electrophysiological description of the first-order visual interneurons, lamina monopolar cells (LMCs), of the bumblebee. Using intracellular recording coupled with dye injection, we found that bumblebee LMCs morphologically resemble those found in the honeybee, although only the LMC type L1 cells could be morphologically matched directly between the species. LMCs could also be classified on the basis of their light response properties as spiking or non-spiking. We also show that some bumblebee LMCs can produce spikes during responses to stimulation with naturalistic light contrasts, a property unusual for these neurons. [ABSTRACT FROM AUTHOR]

This study examines the mechanism underlying one way in which bumblebees are known to develop a preference for symmetric patterns: through prior non-differential reinforcement on simple patterns (black discs and white discs). In three experiments, bees were given a choice among symmetric and asymmetric black-and-white non-rewarding patterns presented at the ends of corridors in a radial maze. Experimental groups had prior rewarded non-discrimination training on white patterns and black patterns, while control groups had no pre-test experience outside the colony. No preference for symmetry was obtained for any of the control groups. Prior training with circular patterns highlighting a horizontal axis of symmetry led to a specific subsequent preference for horizontal over vertical symmetry, while training with a vertical axis abolished this effect. Circles highlighting both axes created a general avoidance of asymmetry in favour of symmetric patterns with vertical, horizontal or both axes of symmetry. Training with plain circles, but not with deformed circles, led to a preference for symmetry: there was no evidence that the preference emerged just by virtue of having attention drawn away from irrelevant pattern differences. Our results point to a preference for symmetry developing gradually through first learning to extract an axis of symmetry from simple patterns and subsequently recognizing that axis in new patterns. They highlight the importance of continued learning through non-differential reinforcement by skilled foragers. Floral guides can function not only to guide pollinators to the source of reward but also to highlight an axis of symmetry for use in subsequent floral encounters. [ABSTRACT FROM AUTHOR]

While our conceptual understanding of emotions is largely based on human subjective experiences, research in comparative cognition has shown growing interest in the existence and identification of "emotion-like" states in non-human animals. There is still ongoing debate about the nature of emotions in animals (especially invertebrates), and certainly their existence and the existence of certain expressive behaviors displaying internal emotional states raise a number of exciting and challenging questions. Interestingly, at least superficially, insects (bees and flies) seem to fulfill the basic requirements of emotional behavior. Yet, recent works go a step further by adopting terminologies and interpretational frameworks that could have been considered as crude anthropocentrismand that now seemacceptable in the scientific literature on invertebrate behavior and cognition. This change in paradigm requires, therefore, that the question of emotions in invertebrates is reconsidered from a cautious perspective and with parsimonious explanations. Here we review and discuss this controversial topic based on the recent finding that bumblebees experience positive emotions while experiencing unexpected sucrose rewards, but also incorporating a broader survey of recent literature in which similar claims have been done for other invertebrates.Wemaintain that caution is warranted before attributing emotion-like states to honey bees and bumble bees as some experimental caveatsmay undermine definitive conclusions.We suggest that interpreting many of these findings in terms of motivational drives may be less anthropocentrically biased and more cautious, at least until more careful experiments warrant the use of an emotion-related terminology. [ABSTRACT FROM AUTHOR]

Exposure to carbon dioxide (CO 2 ) has pleiotropic effects in many insect species, ranging from eliciting rapid behavioral responses such as attraction, to dramatic physiological changes, including ovary activation. In bumble bees, CO 2 narcosis causes queens to bypass diapause and initiate egg laying, but its mode of action is not well-understood. Here, we evaluated the effects of CO 2 narcosis on the behavior, physiology and immune function of virgin bumble bee queens ( Bombus impatiens ). We tested the hypothesis that CO 2 induces these changes by stimulating oxidative stress response pathways. We found that CO 2 stimulates ovarian activation and egg production and suppresses lipid (but not glycogen) accumulation in virgin queens. Additionally, CO 2 treated queens were more active (particularly in terms of flight) and performed, but did not receive, more aggressive behaviors compared to controls. Moreover, CO 2 positively affected immune function in queens, reduced transcript levels of 5/6 antioxidant enzyme genes and had no effect on longevity. Thus, although CO 2 treatment stimulated reproduction, we did not observe any evidence of a trade-off in queen health parameters, aside from a reduction in lipids. Overall CO 2 narcosis does not appear to stimulate a typical stress response in virgin bumble bee queens. On the contrary, CO 2 narcosis appears to stimulate changes that prepare queens to cope with the nutritional, metabolic and behavioral challenges associated with reproduction and colony-founding. [ABSTRACT FROM AUTHOR]

The finding of the suitable parameters of an evolutionary algorithm, as the Bumble Bees Mating Optimization (BBMO) algorithm, is one of the most challenging tasks that a researcher has to deal with. One of the most common used ways to solve the problem is the trial and error procedure. In the recent few years, a number of adaptive versions of every evolutionary and nature inspired algorithm have been presented in order to avoid the use of a predefined set of parameters for all instances of the studied problem. In this paper, an adaptive version of the BBMO algorithm is proposed, where initially random values are given to each one of the parameters and, then, these parameters are adapted during the optimization process. The proposed Adaptive BBMO algorithm is used for the solution of the Multicast Routing Problem (MRP). As we would like to prove that the proposed algorithm is suitable for solving different kinds of combinatorial optimization problems we test the algorithm, also, in the Probabilistic Traveling Salesman Problem (PTSP) and in the Hierarchical Permutation Flowshop Scheduling Problem (HPFSP). Finally, the algorithm is tested in four classic benchmark functions for global optimization problems (Rosenbrock, Sphere, Rastrigin and Griewank) in order to prove the generality of the procedure. A number of benchmark instances for all problems are tested using the proposed algorithm in order to prove its effectiveness. [ABSTRACT FROM AUTHOR]

The rewarding orchid, Cremastra appendiculata (Orchidaceae), has a strong floral scent and is pollinated by long-tongued bumble bee queens (Bombus diversus tersatus Smith; Hymenoptera: Apidae). The response of queens of B. diversus tersatus to the scent of C. appendiculata was investigated using a gas chromatography–electroantennographic detector system and Y-tube olfactometer. Gas chromatography–electroantennographic detector analysis of flower extracts showed that seven compounds (nerol, methyl decanoate, methyl dodecanoate, methyl tetradecanoate, methyl hexadecanoate, ethyl dodecanoate, and ethyl tetradecanoate) elicited antennal responses from B. diversus tersatus queens. Further, Y-tube olfactometer test results showed that queens significantly preferred both the flower extracts and synthetic mixture of seven EAD active compounds compared with pentane (a solvent control). These results suggest that floral scents play an important role in attracting queens and promote successful pollination. [ABSTRACT FROM AUTHOR]

Identifying resource preference is considered essential for developing targeted conservation plans but, for many species, questions remain about the best way to estimate preference. Resource preferences for bees are particularly difficult to determine as the resources they collect, nectar and pollen, are challenging to estimate availability and collection. Resources are traditionally measured at the flower or inflorescence level, but these measures of availability do not correspond to the resources actually used by bees. Additionally, it is unclear as to whether common models including availability are appropriate for bees which may target resources regardless of available quantities. Here we first compare two common hypotheses of resource use - the 'random use hypothesis' and the 'linear preferences hypothesis' - using three different measures of availability (pollen, flower and inflorescence) - to determine if one measure of availability was better for understanding bee pollen use. Next, the superior model using availability was compared to a novel model of bee pollen use the 'target use hypothesis'. This model assumes that bees target some resources regardless of how much of each resource is available (but assuming resources are present at a site), and thus models preference without availability data. Of the models including availability, the linear preference model using inflorescence availability best explained the pollen use data. This suggests that bumblebee pollen use is non-random and that cues to identify and locate resources (i.e. display size and quantity) may be more important than the quantity of the resource available (i.e. pollen availability). Additionally, in most cases the target use model explained the data equal to or better than the other models suggesting bee resource use may be better modeled without measured availability data compared to linear models. These results could be important for expanding resource use analysis of bees that are difficult to quantify availability. [ABSTRACT FROM AUTHOR]

In their natural environments, most animals must learn about multiple kinds of rewards, both within and across contexts. Despite this, the majority of research on animal learning involves a single reward type. For example, bees are an important model system for the study of cognition and its ecological consequences, but nearly all research to date on their learning concerns a single reward, nectar (carbohydrates), even though foragers often simultaneously collect pollen (protein). Features of learning under more ecologically realistic conditions involving multiple reward types are thus largely unexplored. To address this gap, we compared performance on a colour-learning task when floral surrogates offered bumblebees, Bombus impatiens , a single type of floral reward versus multiple, nutritionally distinct rewards. In one experiment, bees learned a floral association with nectar either alone or while simultaneously collecting pollen. In a reciprocal experiment, bees learned a floral association with pollen either alone or while simultaneously collecting nectar. Bees that collected pollen while learning about nectar did not suffer any detriment to learning which flower colour offered nectar. However, this was not the case for the reciprocal task: collecting nectar impaired bees' ability to learn and remember associations between floral colour and pollen. Our findings offer new insight into how bees learn in relation to ecologically realistic rewards and how cognitive constraints may shape their behaviour under ecologically realistic foraging scenarios. [ABSTRACT FROM AUTHOR]

Bumblebees are valuable pollinators of numerous wild and cultivated plants. They can forage on variable pollen resources. As some pollen species lack particular nutrients or have global low nutritional quality, it has been suggested that bumblebees mix their pollen incomes to ensure a global balanced diet. The hypothesis that a mixed pollen diet better supports bumblebee colony development than a single pollen diet has been poorly explored., We compared the impact of mono-, di- and trifloral diets on microcolony development of Bombus terrestris using three pollen resources with different nutrient contents ( Cytisus scoparius, Erica sp. and Sorbus aucuparia) as well as their mixes. Nine parameters (e.g. pollen efficacy: total weight of larvae/total weight of pollen collection) were used to compare the microcolony performances. Moreover, we measured the influence of the pollen diversity and nutritional composition on relevant parameters., We showed that microcolonies can potentially better develop on mixed pollen diets, but single pollen diet can also be as good as mixed pollen diet. Moreover, the sterol concentration appeared as a key factor to establish the impact of a pollen diet on the bumblebee colony development., This study reveals that diverse pollen diet does not necessary equate with good colony development and supports the importance of selecting floral resources by considering their nutrient contents for bee conservation management. [ABSTRACT FROM AUTHOR]

We conducted a bee survey in neonicotinoid-treated commercial potato fields using bowl and vane traps in the 2016 growing season. Traps were placed outside the fields, at the field edges, and 10 and 30 m into the fields. We collected 756 bees representing 58 species, with Lasioglossum spp. comprising 73% of all captured bees. We found seven Bombus spp., of which B. impatiens was the only known visitor of potato flowers in our region. The majority of the bees (68%) were collected at the field edges and in the field margins. Blue vane traps caught almost four-times as many bees and collected 30% more species compared to bowl traps. Bee communities did not differ across trap locations but they were different among trap types. We tested B. impatiens visitation to neonicotinoid treated and untreated potato flowers in field enclosures. The amount of time bees spent at flowers and the duration of visits were not significantly different between the two treatments. Our results demonstrate that a diverse assemblage of bees is associated with an agroecosystem dominated by potatoes despite the apparent lack of pollinator resources provided by the crop. We found no difference in B. impatiens foraging behavior on neonicotinoid-treated compared to untreated plants. [ABSTRACT FROM AUTHOR]

Female bees and wasps demonstrate, through their performance of elaborate learning flights, when and where they memorise features of a significant site. An important feature of these flights is that the insects look back to fixate the site that they are leaving. Females, which forage for nectar and pollen and return with it to the nest, execute learning flights on their initial departure from both their nest and newly discovered flowers. To our knowledge, these flights have so far only been studied in females. Here, we describe and analyse putative learning flights observed in male bumblebees Bombus terrestris L. Once male bumblebees are mature, they leave their nest for good and fend for themselves. We show that, unlike female foragers, males always fly directly away from their nest, without looking back, in keeping with their indifference to their natal nest. In contrast, after males have drunk from artificial flowers, their flights on first leaving the flowers resemble the learning flights of females, particularly in their fixation of the flowers. These differences in the occurrence of female and male learning flights seem to match the diverse needs of the two sexes to learn about disparate, ecologically relevant places in their surroundings. [ABSTRACT FROM AUTHOR]

We explored bees’ behavioral flexibility in a task that required transporting a small ball to a defined location to gain a reward. Bees were pretrained to know the correct location of the ball. Subsequently, to obtain a reward, bees had to move a displaced ball to the defined location. Bees that observed demonstration of the technique from a live or model demonstrator learned the task more efficiently than did bees observing a “ghost” demonstration (ball moved via magnet) or without demonstration. Instead of copying demonstrators moving balls over long distances, observers solved the task more efficiently, using the ball positioned closest to the target, even if it was of a different color than the one previously observed. Such unprecedented cognitive flexibility hints that entirely novel behaviors could emerge relatively swiftly in species whose lifestyle demands advanced learning abilities, should relevant ecological pressures arise. [ABSTRACT FROM AUTHOR]

Repeated exposure to inhibitory compounds can drive the evolution of resistance, which weakens chemical defence against antagonists. Floral phytochemicals in nectar and pollen have antimicrobial properties that can ameliorate infection in pollinators, but evolved resistance among parasites could diminish the medicinal efficacy of phytochemicals. However, multicompound blends, which occur in nectar and pollen, present simultaneous chemical challenges that may slow resistance evolution. We assessed evolution of resistance by the common bumble bee gut parasite Crithidia bombi to two floral phytochemicals, singly and combined, over 6 weeks (~100 generations) of chronic exposure. Resistance of C. bombi increased under single and combined phytochemical exposure, without any associated costs of reduced growth under phytochemical-free conditions. After 6 weeks' exposure, phytochemical concentrations that initially inhibited growth by > 50%, and exceeded concentrations in floral nectar, had minimal effects on evolved parasite lines. Unexpectedly, the phytochemical combination did not impede resistance evolution compared to single compounds. These results demonstrate that repeated phytochemical exposure, which could occur in homogeneous floral landscapes or with therapeutic phytochemical treatment of managed hives, can cause rapid evolution of resistance in pollinator parasites. We discuss possible explanations for submaximal phytochemical resistance in natural populations. Evolved resistance could diminish the antiparasitic value of phytochemical ingestion, weakening an important natural defence against infection. [ABSTRACT FROM AUTHOR]

The annotated list of 36 species of bumblebees of Chelyabinsk region is presented. Ten species are newly recorded for this region: Bombus ruderarius (Müller, 1776); B. campestris (Panzer, 1801); B. bohemicus Seidl, 1837; B. barbutellus (Kirby, 1802); B. quadricolor (Lepeletier, 1832); B. sylvestris (Lepeletier, 1832); B. rupestris (Fabricius, 1793); B. patagiatus Nylander, 1848; B. semenoviellus Skorikov, 1910; B. lapidarius (Linnaeus, 1758). The features of bumblebees' distribution in the region and their ecological peculiarities are considered. [ABSTRACT FROM AUTHOR]

Bee population declines are linked to the reduction of nutritional resources due to land-use intensification, yet we know little about the specific nutritional needs of many bee species. Pollen provides bees with their primary source of protein and lipids, but nutritional quality varies widely among host-plant species. Therefore, bees might have adapted to assess resource quality and adjust their foraging behavior to balance nutrition from multiple food sources. We tested the ability of two bumble bee species, Bombus terrestris and Bombus impatiens, to regulate protein and lipid intake. We restricted B. terrestris adults to single synthetic diets varying in protein:lipid ratios (P:L). The bees over-ate protein on low-fat diets and over-ate lipid on high-fat diets to reach their targets of lipid and protein, respectively. The bees survived best on a 10:1 P:L diet; the risk of dying increased as a function of dietary lipid when bees ate diets with lipid contents greater than 5:1 P:L. Hypothesizing that the P:L intake target of adult worker bumble bees was between 25:1 and 5:1, we presented workers from both species with unbalanced but complementary paired diets to determine whether they self-select their diet to reach a specific intake target. Bees consumed similar amounts of proteins and lipids in each treatment and averaged a 14:1 P:L for B. terrestris and 12:1 P:L for B. impatiens. These results demonstrate that adult worker bumble bees likely select foods that provide them with a specific ratio of P:L. These P:L intake targets could affect pollen foraging in the field and help explain patterns of host-plant species choice by bumble bees. [ABSTRACT FROM AUTHOR]

Picture-object correspondence provides an alternate method of investigating delayed matching by providing a cue (picture) which may be spontaneously perceived as similar but different from a corresponding target. Memory for, and corresponding choice of, a target corresponding to a cue could be facilitated by the use of a picture. Bumblebees have been found to both easily differentiate images from corresponding objects but also spontaneously perceive a similarity between the two. Herein, an approach was designed to test the possible use of picture cues to signal reward in a delayed matching task. Target choice preference corresponding to picture cues was tested among three bumblebee (Bombus impatiens) colonies using photograph cues (presented prior to target stimuli) corresponding to one of four target stimuli. Photograph cues were the only predictor of corresponding target reward, presented in stable locations. Rewarded and unrewarded tests show a choice preference significantly higher than chance for targets matching the cue. Results suggest that bumblebees can learn to use picture cues in a delayed matching task. Furthermore, experience, conditions of reward inconsistency and location, are discussed as possible contributing factors to learning in a delayed matching task. [ABSTRACT FROM AUTHOR]

In most bumblebee species, queens mate with only one male, but males can mate more than once. However, the effects of male remating on colony foundation success of queens remain poorly understood. To test for effects of male remating, we assigned Bombus terrestris queens randomly to one of two groups: virgin males or non-virgin males that have mated once before. When males were allowed to mate for a second time with virgin queens, 58.57 % successfully remated. There was no significant difference in queen hibernation survival between groups, but queens mated with non-virgin males were more successful in founding a colony, and produced more workers and males than queens mated with virgin males. The mean copulation duration for the second mating of males (48.02 ± 14.36 min) was substantially longer than for the first mating (32.44 ± 8.74 min). Results also showed that male weight influenced both male remating success and copulation duration. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effects of Elado-dressed winter oilseed rape (OSR, 10 g clothianidin & 2 g beta-cyfluthrin/kg seed) on the development, reproduction and behaviour of large earth bumble bees ( Bombus terrestris) as part of a large-scale monitoring field study in Northern Germany, where OSR is usually cultivated at 25-33 % of the arable land. Both reference and test sites comprised 65 km in which no other crops attractive to pollinating insects were present. Six study locations were selected per site and 10 bumble bee hives were placed at each location. At each site, three locations were directly adjacent to OSR fields and three locations were situated 400 m distant from the nearest OSR field. The development of colonies was monitored from the beginning of OSR flowering in April until June 2014. Pollen from returning foragers was analysed for its composition. An average of 44 % of OSR pollen was found in pollen loads of bumble bees indicating that OSR was a major resource for the colonies. At the end of OSR flowering, hives were transferred to a nature reserve until the end of the study. Colony development in terms of hive weight and the number of workers showed a typical course with no statistically significant differences between the sites. Reproductive output was comparatively high and not negatively affected by the exposure to treated OSR. In summary, Elado-dressed OSR did not cause any detrimental effects on the development or reproduction of bumble bee colonies. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO 2) has pleiotropic effects on insect physiology and behavior. Although diverse, many impacts are related to changes in metabolism and reallocation of macronutrients. Here we examined the metabolic shift induced by CO 2 and its regulation using Bombus impatiens. CO 2 applied to bumble bee gynes induces bypass of diapause and transition into reproduction. We analyzed ovary activation and macronutrient amounts in four tissues/body parts (fat body, thorax, ovaries, and crop) at three timepoints following CO 2 administration. To tease apart the effects of CO 2 on reproduction and metabolism, we monitored the metabolic changes in gynes following ovary removal and CO 2 narcosis. We also explored the role of juvenile hormone in mediating CO 2 impact by feeding queens with a JH antagonist (Precocene). Gynes ovary activation was increased following CO 2 treatment. Additionally, CO 2 -treated gynes showed lower lipid amount in the fat body and higher glycogen and protein amount in the ovary ten days after the treatment. CO 2 treatment following ovary removal also resulted in decreased fat body lipids, suggesting that CO 2 operates by inducing a metabolic shift independent of reproduction. Lastly, gynes fed with precocence did not show a metabolic shift following CO 2 , suggesting CO 2 impact is mediated via juvenile hormone. Overall, these data suggest that CO 2 induces transfer of macronutrients and utilization of stored reserved by accelerating metabolism. The proposed mechanism of CO 2 may explain many of the pleiotropic effects of CO 2 across species and can aid in understanding how this common anastatic influences insect physiology. [Display omitted] • CO2 induces re-allocation of macronutrients in bumble bee gynes. • CO2 effect on metabolism is independent from its effect on reproduction. • Feeding gynes with JH antagonist (precocene) blocks the effect of CO2 on metabolism. • CO2 impact of metabolism and reproduction is mediated via Juvenile hormone. [ABSTRACT FROM AUTHOR]

To make a smooth touchdown when landing, an insect must be able to reliably control its approach speed as well as its body and leg position--behaviors that are thought to be regulated primarily by visual information. Bumblebees forage and land under a broad range of light intensities and while their behavior during the final moments of landing has been described in detail in bright light, little is known about how this is affected by decreasing light intensity. Here, we investigate this by characterizing the performance of bumblebees, B. terrestris, landing on a flat platform at two different orientations (horizontal and vertical) and at four different light intensities (ranging from 600 lx down to 19 lx). As light intensity decreased, the bees modified their body position and the distance at which they extended their legs, suggesting that the control of landing in these insects is visually mediated. Nevertheless, the effect of light intensity was small and the landings were still well controlled, even in the dimmest light. We suggest that the changes in landing behavior that occurred in dim light might represent adaptations that allow the bees to perform smooth landings across the broad range of light intensities at which they are active. [ABSTRACT FROM AUTHOR]

Nutritional deficits may be one factor contributing to the ongoing decline of wild and managed bees. As a consequence, interest in understanding the effect of floral resource availability on nutritional intake - and subsequently bee health and performance - has increased. However, the proximate mechanisms underlying bee foraging choices are still poorly understood. We do, for instance, not yet know whether and how bees assess the nutritional quality of pollen or whether they use information on pollen quality to adjust foraging patterns. In a previous study, we showed that Bombus terrestris workers use their sense of taste to discriminate pollen differing in concentration and, thus, nutrient content. We now investigated whether they translate this ability into foraging behavior by observing microcolonies offered the choice between two feeders containing different pollen types and concentrations and, thus, qualities. We examined whether bumblebees used direct (chemotactile) or indirect (olfactory) cues to assess pollen quality and whether they individually assessed pollen quality or relied on larval feedback. By changing pollen quality after 21 days, we further tested whether information on pollen quality was subsequently associated with other (faster assessable) cues (e.g., odor) or continuously re-assessed. We found that bees always preferred pollen of higher quality and individually assessed quality based on chemotactile cues. Moreover, changing pollen quality resulted in rapid equivalent changes in foraging behavior, even without feedback from larvae. Consequently, individual bumblebee foragers continuously re-assess pollen quality to provide their colonies with high-quality food. Significance statement: The ongoing decline of wild and managed bees is likely driven by several factors with nutritional deficits being one of them. Because bees are amongst the most important pollinators, interest in understanding the effect of floral resource availability on nutritional intake and, subsequently, bee health and performance has increased. However, the proximate mechanisms underlying bee foraging choices are still poorly understood. In this study, we investigated how bumblebees differentiate between different pollen qualities by observing microcolonies offered the choice between different diets. We found that bees always preferred pollen of higher quality and individually assessed quality based on chemotactile cues. This finding increases our understanding of how social bees assess nutritional quality and make appropriate foraging choices. [ABSTRACT FROM AUTHOR]

Invasive species are considered a main driver of pollinator declines, yet the direct effects of invasive alien plants on pollinators are poorly understood., Abundant, invasive plant species can provide a copious nectar resource for native pollinators. However, the nectar of some plants contains secondary compounds, usually associated with defence against herbivores. The impacts of these compounds on pollinators are often unknown., We compared how consumption of grayanotoxin I and III, natural secondary compounds in the nectar of invasive Rhododendron ponticum L., affected three native bee species: a honeybee, ( Apis mellifera L.), a solitary mining bee ( Andrena carantonica, Pérez) and a bumblebee, ( Bombus terrestris, L.)., Survival of the solitary bee and the bumblebee species was not affected by either grayanotoxin, but honeybees were ∼20× more likely to die when fed solutions containing grayanotoxin I. Furthermore, solitary bees were deterred from feeding and exhibited malaise behaviours indicative of sublethal toxicity in response to consumption of grayanotoxin I. In contrast, grayanotoxins did not affect bumblebee survival or behaviour, even when bees were subjected to multiple stressors (parasite infection or food stress)., Our experiments suggest that while R. ponticum provides abundant floral nectar, it is only available as a food resource to pollinators that tolerate grayanotoxins. Pollinators whose health is negatively affected by grayanotoxins may experience negative impacts from R. ponticum invasion directly (if they consume R. ponticum nectar) or indirectly (if native floral resources are replaced by R. ponticum)., Our study makes a novel comparison of the effects of a natural nectar secondary compound on three pollinator species and clearly demonstrates drastic variation in the responses of different key pollinator taxa to a nectar toxin. Our findings are thus in congruence with literature demonstrating the varying effects of invasive plant chemistry on native foliar herbivores, and our work demonstrates that nectar chemistry should be taken into account when determining the impacts of plant invasion for native pollinators. [ABSTRACT FROM AUTHOR]

ABSTRACT Global declines of bumble bees and other pollinator populations are of concern because of their critical role for crop production and maintenance of wild plant biodiversity. Although the consensus among scientists is that the interaction of many factors, including habitat loss, forage scarcity, diseases, parasites, and pesticides, potentially plays a role in causing these declines, pesticides have received considerable attention and scrutiny. In response, regulatory agencies have introduced more stringent pollinator testing requirements for registration and reregistration of pesticides, to ensure that the risks to pollinators are minimized. In this context, guidelines for testing bumble bees ( Bombus spp.) in regulatory studies are not yet available, and a pressing need exists to develop suitable protocols for routine higher-tier studies with these non- Apis sp., social bees. To meet this need, Bayer CropScience LP, Syngenta Crop Protection LLC US, and Valent USA. Corporation organized a workshop bringing together a group of global experts on bumble bee behavior, ecology, and ecotoxicology to discuss and develop draft protocols for both semi-field (Tier II) and field (Tier III) studies. The workshop was held May 8-9, 2014, at the Bayer Bee Care Center, North Carolina, USA. The participants represented academic, consulting, and industry scientists from Europe, Canada, the United States, and Brazil. The workshop identified a clear protection goal and generated proposals for basic experimental designs, relevant measurements, and endpoints for both semifield (tunnel) and field tests. These initial recommendations are intended to form the basis of discussions to help advance the development of appropriate protocol guidelines. Integr Environ Assess Manag 2016;12:222-229. © 2015 The Authors. Integrated Environmental Assessment and Management Published by SETAC [ABSTRACT FROM AUTHOR]

Summary Iridescence is a form of structural coloration, produced by a range of structures, in which hue is dependent on viewing angle [ 1–4 ]. One of these structures, the diffraction grating, is found both in animals (for example, beetles [ 2 ]) and in plants (on the petals of some animal pollinated flowers [ 5 ]). The behavioral impacts of floral iridescence and its potential ecological significance are unknown [ 6–9 ]. Animal-pollinated flowers are described as “sensory billboards” [ 10 ], with many floral features contributing to a conspicuous display that filters prospective pollinators. Yet floral iridescence is more subtle to the human eye than that of many animal displays because the floral diffraction grating is not perfectly regular [ 5–9 ]. This presents a puzzle: if the function of petals is to attract pollinators, then flowers might be expected to optimize iridescence to increase showiness. On the other hand, pollinators memorize floral colors as consistent advertisements of reward quality, and iridescence might corrupt flower color identity. Here we tested the trade-off between flower detectability and recognition, requiring bumblebees ( Bombus terrestris ) to identify artificial flowers that varied in pigmentation and degree of iridescence. We find that iridescence does increase target detectability but that “perfect” iridescence (produced by an artificial diffraction grating) corrupts target identity and bees make many mistakes. However, “imperfect” floral iridescence does not lead to mistaken target identity, while still benefitting flower detectability. We hypothesize that similar trade-offs might be found in the many naturally “imperfect” iridescence-producing structures found in animal-animal, as well as other plant-animal, interactions. [ABSTRACT FROM AUTHOR]

The South American lulo ( Solanum quitoense Lam.) is a crop plant of the Andes of Ecuador and Colombia, pollinated by South American bumblebees, such as, Bombus atratus Franklin. The cultivation of lulo outside of its native range, for example in European glasshouses, requires the presence of efficient pollinators to enable high fruit set and yield. Until now, the suitability of Bombus terrestris L., native to Europe and commonly used in agriculture, has been untested for this purpose. In this study, the pollen-collecting behaviour of B. terrestris when visiting lulo flowers was investigated. It was shown that B. terrestris adopted the lulo as a pollen source, and on average visited three flowers per minute, had five buzzing events per stay and foraged for 15 s on a single flower, independently of the previous number of visits and level of bruising to the anthers. The pollination efficiency of five different treatments was evaluated: (i) exclusion of bees, (ii) single and (iii) multiple visits of B. terrestris, (iv) self- and (v) cross-pollination by hand. The results clearly demonstrated that, for fruit set, pollination is crucial. It was also found that lulo flowers can be successfully self-pollinated, but give 25% fewer fruit set compared with pollination via multiple bumblebee visits, or cross-pollination by hand. Fruit set, seed set and fruit size were as high with pollination by B. terrestris as with cross-pollination by hand, indicating that this bumblebee is an appropriate pollinator for lulo. However, B. terrestris was conspicuously less effective when a flower was visited only once. Therefore, when growing lulos commercially, multiple bumblebee visits should be encouraged, but it is likely that the behaviour of B. terrestris would ensure this anyway. Our results indicate that B. terrestris is a suitable and efficient pollinator for the production of lulo fruits. [ABSTRACT FROM AUTHOR]

Bee species interactions can benefit plant pollination through synergistic effects and complementary effects, or can be of detriment to plant pollination through competition effects by reducing visitation by effective pollinators. Since specific bee interactions influence the foraging performance of bees on flowers, they also act as drivers to regulate the assemblage of flower visitors. We selected squash (Cucurbita pepo L.) and its pollinators as a model system to study the foraging response of honey bees to the occurrence of bumble bees at two types of sites surrounded by a high amount of natural habitats (≥ 58% of land cover) and a low amount of natural habitats (≤ 12% of land cover) in a highland agricultural ecosystem in China. At the individual level, we measured the elapsed time from the departure of prior pollinator(s) to the arrival of another pollinator, the selection of honey bees for flowers occupied by bumble bees, and the length of time used by honey bees to explore floral resources at the two types of sites. At the community level, we explored the effect of bumble bee visitation on the distribution patterns of honey bees on squash flowers. Conclusively, bumble bee visitation caused an increase in elapsed time before flowers were visited again by a honey bee, a behavioral avoidance by a newly-arriving honey bee to select flowers occupied by bumble bees, and a shortened length of time the honey bee takes to examine and collect floral resources. The number of overall bumble bees on squash flowers was the most important factor explaining the difference in the distribution patterns of honey bees at the community level. Furthermore, decline in the number of overall bumble bees on the squash flowers resulted in an increase in the number of overall honey bees. Therefore, our study suggests that bee interactions provide an opportunity to enhance the resilience of ecosystem pollination services against the decline in pollinator diversity. [ABSTRACT FROM AUTHOR]

The learning capacities of males and females may differ with sex-specific behavioural requirements. Bumblebees provide a useful model system to explore how different lifestyles are reflected in learning abilities, because their (female but sterile) workers and males engage in fundamentally different behaviour routines. Bumblebee males, like workers, embark on active flower foraging but in contrast to workers they have to trade off their feeding with mate search, potentially affecting their abilities to learn and utilize floral cues efficiently during foraging. We used a serial colour-learning task with freely flying males and workers to compare their ability to flexibly learn visual floral cues with reward in a foraging scenario that changed over time. Male bumblebees did not differ from workers in both their learning speed and their ability to overcome previously acquired associations, when these ceased to predict reward. In all foraging tasks we found a significant improvement in choice accuracy in both sexes over the course of the training. In both sexes, the characteristics of the foraging performance depended largely on the colour difference of the two presented feeder types. Large colour distances entailed fast and reliable learning of the rewarding feeders whereas choice accuracy on highly similar colours improved significantly more slowly. Conversely, switching from a learned feeder type to a novel one was fastest for similar feeder colours and slow for highly different ones. Overall, we show that behavioural sex dimorphism in bumblebees did not affect their learning abilities beyond the mating context. We discuss the possible drivers and limitations shaping the foraging abilities of males and workers and implications for pollination ecology. We also suggest stingless male bumblebees as an advantageous alternative model system for the study of pollinator cognition. [ABSTRACT FROM AUTHOR]