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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]

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]

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]

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]

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]

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]

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]

Bumblebees and honeybees have been the subjects of a great deal of recent research in animal cognition. Many of the major topics in cognition, including memory, attention, concept learning, numerosity, spatial cognition, timing, social learning, and metacognition have been examined in bumblebees, honeybees, or both. Although bumblebees and honeybees are very closely related, they also differ in important ways, including social organization, development, and foraging behaviour. We examine whether differences between bumblebees and honeybees in cognitive processes are related to differences in their natural history and behaviour. There are differences in some cognitive traits, such as serial reversal learning and matching-to-sample, that appear related to differences between bumblebees and honeybees in foraging and social behaviour. Other cognitive processes, such as numerosity, appear to be very similar. Despite the wealth of information that is available on some aspects of bumblebee and honeybee cognition and behaviour, there are relatively few instances, however, in which adequate data exist to make direct comparisons. We highlight a number of phenomena, including concept learning, spatial cognition, timing, and metacognition, for which targeted comparative research may reveal unexpected adaptive variation in cognitive processes in these complex animals. This article is part of a Special Issue entitled: In Honor of Jerry Hogan. [ABSTRACT FROM AUTHOR]

Stress has complex effects on learning and memory, depending on both the type of stress and when the animal experiences it. Honeybees and bumblebees are agriculturally important pollinators for whom the effects of stress are extremely relevant. These pollinators are often transported long distances during which colonies experience severe physical disturbance, causing stress to individuals prior to their release for pollination. Under natural foraging conditions, bees are excellent at learning about the flowers they forage from, including associations between floral stimuli and rewards. However, it is not clear how stress might affect bees’ abilities to learn and remember floral features. Here we address the effects of acute stress on learning and memory in the bumble bee, Bombus impatiens . Using the Proboscis Extension Response (PER) protocol, we look at stress effects on learning and memory in three experiments. After being trained to a conditioned stimulus, we addressed: (1) the effect of 24 h and (2) 30 min of stress on the recall of this learned association and (3) the effect of stress on subsequently learning an association. We found that 24 h of stress after learning appeared to improve memory recall, and there was a trend in the same direction for 30 min of stress. However, bees that were stressed prior to learning an association did not differ from unstressed bees in their ability to learn or remember an association. Our finding that stress has effects on memory in the bumblebee could have implications for their use in behavioral experiments and for promoting the success of both managed and wild populations. [ABSTRACT FROM AUTHOR]

Bumblebees integrate cues associated with food that they experience within their nest. Both experienced and naïve workers rely on odours in the nectar collected by foragers and stored in honeypots to gain information about currently available food sources. The ability of workers to retain memories of these odours and to orient towards them when they leave the nest affects both foraging efficiency and food yield for the colony. In this study, we added sugar solution containing a floral scent (i.e. training scent) directly to empty honeypots within nests of Bombus impatiens in the absence of all other stimuli normally associated with successful foragers. To assess bee learning and memory, we quantified the effects of (a) the number of exposures to the training scent during conditioning, (b) the number of days elapsed post-conditioning (3 days vs. 6 days) and (c) bee age, on appetitive choice of the training scent relative to an unfamiliar scent. A high proportion of the bees of all ages (i.e. 74–80%) contacted the scented syrup we supplied briefly to colonies, with most contacting it once but some as many as 14 times. Most of the bees that may have experienced the training scent in the hive atmosphere but failed to contact a honeypot containing the scented sucrose solution (i.e. bees for which the training scent was familiar but unrewarded) exhibited no response to either the familiar or unfamiliar scent; the few that responded had no preference for either scent. More frequent contact with the scented sucrose increased the likelihood a bee would respond to the scent subsequently. Bees that contacted the scented nectar 1–4 times during conditioning preferred the rewarded odour when tested 3 days later, but after 6 days their scent choice was random, suggesting they retained no memory of it. In contrast, bees that contacted the scented nectar 5–14 times chose the rewarded odour over an unrewarded odour 23 of 24 times when tested 6 days after exposure. This is the first confirmation of social learning in B. impatiens. Our results highlight the importance of direct contact with scented nectar in honeypots and the strong long-term memory of a rewarded scent acquired through relatively brief but repeated exposure to it. [ABSTRACT FROM AUTHOR]

Highlights: [•] An experimental approach to reproductive conflict in bumblebees. [•] Orphaned workers were paired according to levels of social activity. [•] Socially active pairs were more aggressive. [•] Aggression was not necessary for ovarian development. [•] Presence of brood depressed aggression and ovarian development. [ABSTRACT FROM AUTHOR]

Abstract: The effects of floral herbivores on floral traits may result in alterations in pollinator foraging behaviour and subsequently influence plant reproductive success. Fed-upon plants may have evolved mechanisms to compensate for herbivore-related decreased fecundity. We conducted a series of field experiments to determine the relative contribution of floral herbivores and pollinators to female reproductive success in an alpine herb, Pedicularis gruina, in two natural populations over two consecutive years. Experimental manipulations included bagging, hand supplemental, geitonogamous pollination, and simulated floral herbivory. Bumblebees not only avoided damaged flowers and plants but also decreased successive visits of flowers in damaged plants, and the latter may reduce the level of geitonogamy. Although seed set per fruit within damaged plants was higher than that in intact plants, total seed number in damaged plants was less than that in intact plants, since floral herbivory-mediated pollinator limitation led to a sharp reduction of fruit set. Overall, the results suggest that resource reallocation within inflorescences of damaged plants may partially compensate for a reduction in seed production. Additionally, a novel finding was the decrease in successive within-plant bumblebee visits following floral herbivory. This may increase seed quantity and quality of P. gruina since self-compatible species exhibit inbreeding depression. The patterns of compensation of herbivory and its consequences reported in this study give an insight into the combined effects of interactions between floral herbivory and pollination on plant reproductive fitness. [Copyright &y& Elsevier]

Flexible division of labour is a key feature of social insects. Our understanding of individual response behaviour and how it is integrated into a functioning colony is still patchy. Most theoretical studies addressing this question are based on the assumption that workers have intrinsic and often fixed response thresholds for task-related stimuli. Here, we investigated the plasticity in worker fanning response behaviour in a bumblebee, Bombus terrestris. Using a temperature-controlled brood dummy, we first asked whether the fanning response is modulated by rate of temperature change. Second, we examined to what extent the fanning response is influenced by recent fanning experience. Our results show that the individual fanning response is modulated by both the rate of temperature increase and recent experience. Workers responded at lower temperatures and with a higher probability when the temperature of the brood dummy increased slowly compared with more rapid temperature increases. Workers that repeatedly responded to an increase in brood dummy temperature with fanning showed a significant decrease in their response thresholds, whereas the response thresholds of control workers that experienced the same treatment but did not gather fanning experience remained unchanged. The decrease in response threshold was pronounced when the time interval between two successive fanning events was less than 6h. When 16h or more separated fanning events, individual fanning responses returned to higher threshold levels. We suggest that experience-dependent modulation of response thresholds plays an important role in the behavioural differentiation of workers and the flexibility of insect colonies. [Copyright &y& Elsevier]

It is now recognized that many vertebrates and a few invertebrates show individual-specific consistency in their behaviour across time and context, sometimes in ways that can be paralleled with human personality. Our work aimed at assessing behavioural consistency in a social insect: the bumblebee Bombus terrestris. We focused on a behavioural dimension commonly used in personality studies: the response of an individual to novelty (neophilia/neophobia spectrum). We used a foraging paradigm to quantify individual bees’ response to novel flower colours and to assess the repeatability of this response over time. As for vertebrates, most individual bumblebees responded to a novel stimulus by increasing the time they spent investigating it compared to known stimuli. Using a new statistical approach, the consistency model, we found that individual bees tended to be consistent in their response to novelty over a few hours but were not consistent in their behaviour over 3 days. We conclude that for the neophilia/neophobia paradigm used here, bumblebee foragers do not fulfil the criteria for animal personality in the common sense of the term. Instead their behavioural response to novelty appears to be plastic, varying on a day to day basis. [ABSTRACT FROM AUTHOR]

Insects use visual estimates of flight speed for a variety of behaviors, including visual navigation, odometry, grazing landings and flight speed control, but the neuronal mechanisms underlying speed detection remain unknown. Although many models and theories have been proposed for how the brain extracts the angular speed of the retinal image, termed optic flow, we lack the detailed electrophysiological and behavioral data necessary to conclusively support any one model. One key property by which different models of motion detection can be differentiated is their spatiotemporal frequency tuning. Numerous studies have suggested that optic-flow-dependent behaviors are largely insensitive to the spatial frequency of a visual stimulus, but they have sampled only a narrow range of spatial frequencies, have not always used narrowband stimuli, and have yielded slightly different results between studies based on the behaviors being investigated. In this study, we present a detailed analysis of the spatial frequency dependence of the centering response in the bumblebee Bombus impatiens using sinusoidal and square wave patterns. [ABSTRACT FROM AUTHOR]

Social insect societies are considered to be composed of many extremely cooperative individuals. While workers are traditionally believed to behave altruistically, recent studies have revealed behaviors that are more selfish. One such example is intraspecific social parasitism, where workers invade conspecific colonies and produce male offspring that are reared by unrelated host workers. Such intraspecific parasitism has been reported in honeybees ( Apis cerana, and A. florea) and “semi-wild” bumblebee colonies of Bombus terrestris. Here we report on intraspecific social parasitism by workers in “wild” colonies of the bumblebee B. deuteronymus. Three of the 11 B. deuteronymus colonies studied were invaded by non-natal workers, of which 75% became reproductive and produced 19% of the adult males. The invading non-natal workers produced significantly more males than resident natal workers and the non-natal brood was not discriminated against by the natal workers. [ABSTRACT FROM AUTHOR]

Pollinators are confronted with spatial heterogeneity in floral resources. Acquiring information about their environment enables pollinators to exploit floral resources optimally, and hence strongly affects their fitness. Despite their evolutionary importance, spatial resource distribution and social information use have never been addressed in a plant–pollinator framework. We experimentally tested the effects of inadvertent social information (ISI) use (without or with an experienced demonstrator) in relation to spatial flower distribution (random or patchy) in foraging Bombus terrestris. We studied naïve bees'' associative learning when confronted with rewarding and nonrewarding flowers that differed slightly in colour, reproducing the natural mimicry of deceptive species. Naïve bees were more efficient foragers with than without a demonstrator in the patchy flower distribution, suggesting that they used ISI from conspecifics, probably in the form of social attraction at the patch scale. In the random flower distribution, however, ISI did not improve performance of naïve bees, and could not replace individual sampling. Analyses of nonrewarding intraspecific transitions indicate that the efficiency of naïve bees in deceptive species pollination was lowered when rewarding and nonrewarding inflorescences were patchily distributed and especially when bees relied on ISI. Thus, spatial flower distribution and ISI availability interact in determining pollinator behaviour, which has important consequences for plant community pollination. This suggests that bumblebees are adapted to exploit patchily distributed resources socially, a characteristic that might be exploited by deceptive plant species. By coupling behavioural and community ecology, this study offers promising perspectives for cognitive ecology studies in plant–pollinator interactions. [Copyright &y& Elsevier]

Abstract The flower in Aconitum has five violet sepals. Its morphology is unique and thought to be adapted for pollination by bumblebees. To assess the adaptive significance of Aconitum flower morphology, we examined the function of the five sepals in bumblebee-pollination. We manipulated the flower by removing the sepals and then observed and measured bumblebee pollination efficiency in a single visit. Bumblebee behavior differed somewhat on the manipulated flowers. Manipulation of the two lower sepals led to a pollination efficiency that was the same as no manipulation. Pollination efficiency was lowered significantly after lateral sepal manipulation, and this was caused by the absence of the arch structure normally formed by two lateral sepals changing the posture of the pollinator. Therefore, it was postulated that the arch structure formed by the lateral sepals functions to ensure correct pollination. [ABSTRACT FROM AUTHOR]