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The western honey bee, Apis mellifera, lives worldwide in approximately 102 million managed hives but also wild throughout much of its native and introduced range. Despite the global importance of A. mellifera as a crop pollinator, wild colonies have received comparatively little attention in the scientific literature and basic information regarding their density and abundance is scattered. Here, we review 40 studies that have quantified wild colony density directly (n = 33) or indirectly using genetic markers (n = 7) and analyse data from 41 locations worldwide to identify factors that influence wild colony density. We also compare the density of wild and managed colonies at a regional scale using data on managed colonies from the Food and Agriculture Organization (FAO). Wild colony densities varied from 0.1 to 24.2/km2 and were significantly lower in Europe (average of 0.26/km2) than in Northern America (1.4/km2), Oceania (4.4/km2), Latin America (6.7/km2) and Africa (6.8/km2). Regional differences were not significant after controlling for both temperature and survey area, suggesting that cooler climates and larger survey areas may be responsible for the low densities reported in Europe. Managed colony densities were 2.2/km2 in Asia, 1.2/km2 in Europe, 0.2/km2, in Northern America, 0.2/km2 in Oceania, 0.5/km2 in Latin America and 1/km2 in Africa. Wild colony densities exceeded those of managed colonies in all regions except Europe and Asia. Overall, there were estimated to be between two and three times as many wild colonies as managed worldwide. More wild colony surveys, particularly in Asia and South America, are needed to assess the relative density of wild and managed colonies at smaller spatial scales. [ABSTRACT FROM AUTHOR]

Simple Summary: Why do plants have showy flowers? Clearly, many plant species must attract pollinators and have floral adaptations for this. However, some flowers attract insects without showy petals. This suggests that a key function of showy visual signals is to attract naïve, first-time pollinator visitors. This is similar to how a restaurant with a large sign and showy visual signals may be especially important in gaining first-time visits when competing with other establishments or plants. Customers or pollinators will know if the first visit is rewarding and use this to decide whether to revisit. First, they must visit. Most flowers and restaurants would benefit from more visitors. Restaurants usually have empty tables, and many flowers are pollen limited in their reproduction. Here, we manipulated the ray petals of inflorescences of two garden flowers to test the hypothesis that the role of showy visual signals is to attract naïve visitors. On their first inflorescence visit to both species, naïve honey bees and bumble bees were more likely to visit intact inflorescences, than those with ray petals removed. However, by the tenth consecutive inflorescence, bees showed no preference. A positive correlation was observed between the visitation of inflorescences with no petals and the inflorescence number on both study plants, for both bees. These results strongly suggest that a key function of showy petals is to attract naïve, first-time visitors. Flower evolution includes a range of questions concerning the function of showy morphological features such as petals. Despite extensive research on the role of petals in attracting pollinators, there has been little experimental testing of their importance in attracting naïve versus experienced flower-visitors. In an exploratory field study, we manipulated the ray petals of inflorescences of two garden flowers, Rudbeckia hirta and Helenium autumnale, to test the hypothesis that these showy structures primarily function to attract first-time, naïve, visitors. On their first inflorescence visit to both species, naïve honey bees and bumble bees were more likely to visit intact inflorescences, than those with ray petals removed. However, by the tenth consecutive inflorescence on the same visit to the flower patch, test insects showed no preference. A positive correlation was observed between the visitation of inflorescences with zero petals and inflorescence number on both study plants, for both bees. These results suggest that a key function of showy petals is to attract naïve, first-time visitors. Similar to how a restaurant attracts diners with a large sign, showy signals may be vital to enticing first-time visitors when competing with other establishments or plants for customers or pollinators. We hope the findings of this exploratory study will stimulate further work in this area. [ABSTRACT FROM AUTHOR]

Agricultural intensification has been implicated in global biodiversity declines. In the European Union, agri‐environmental schemes are designed to address this. For pollinating insects, funding has been provided to sow wildflower mixes. However, previous research indicates that a suite of agricultural weeds are also of great importance to pollinators.Here, we compare the biodiversity associated with the species which are considered harmful to agricultural production and legally deemed as 'injurious' by the United Kingdom 1959 Weeds Act (common ragwort Jacobaea vulgaris, creeping thistle Cirsium arvense, spear thistle C. vulgare, curled dock Rumex crispus and broadleaved dock R. obtusifolius), with plant species recommended for pollinator‐targeted agri‐environmental options.In our field study, the abundance and diversity of pollinators visiting the weed species averaged twice that of the recommended plants and included the main insect orders (Coleoptera, Diptera, Hymenoptera and Lepidoptera). This relationship was also seen in a meta‐analysis of literature data, which indicates that fourfold more flower‐visitor species and fivefold more conservation‐listed species are associated with the weeds. Additionally, the literature shows that twice the number of herbivorous insect species are associated with these plants.We suggest that several factors are responsible for this pattern. Injurious weed species are widely distributed, their flower morphology allows access to a wide variety of pollinator species, and they produce, on average, four times more nectar sugar than the recommended plant species.Freedom of information requests to public bodies such as local councils, Natural England and Highways England indicate that c. £10 million per year is spent controlling injurious weeds. Meanwhile, the cost of the four pollinator‐targeted agri‐environmental options in the United Kingdom exceeds £40 m annually.Synthesis and applications. Our results clearly show that weeds have an underappreciated value to biodiversity. Unfortunately, current UK agricultural policy encourages neither land sparing for nor land sharing with weeds. The UK government is, however, currently committed to overhauling agricultural payments to encourage more wildlife‐ and climate‐friendly practices. Thus, the challenge of reconciling the conflicts between agricultural production and these native and biodiverse species should be a renewed priority to land managers, researchers and policymakers. [ABSTRACT FROM AUTHOR]

Pollination is an important ecological process. However, plant and pollinator needs are not always met. Commonly, pollen limitation reduces seed set or bees experience nectar dearth. Using a cost‐benefit approach, we show that natural selection will lead to lower nectar production when pollinators are abundant, and vice‐versa. At the community level, competition among plants for pollinators causes positive feedback that exacerbates pre‐existing seasonal imbalances between nectar supply and demand. When pollinators are scarce, plants will be selected to produce more nectar to outcompete other plants in attracting pollinators, and when pollinators are abundant, plants will be selected to produce less nectar. We suggest ways to test this positive feedback hypothesis and note that evidence for seasonal variation in nectar availability provides preliminary empirical support. If correct, our hypothesis indicates that pollination faces a particular challenge in balancing nectar supply with pollinator demand and is a further example of the underappreciated role of positive feedback in ecology and evolution. [ABSTRACT FROM AUTHOR]

Cultivation of the mass‐flowering crop oilseed rape (OSR), Brassica napus, can provide insects with super‐abundant nectar and pollen while in bloom. Several authors have suggested breeding cultivars to produce more abundant nectar and pollen to help mitigate insect decline. However, in Britain most, 95%, OSR blooms in spring (March–May), which has been suggested to be a period of nectar surplus and reduced exploitative competition. Therefore, a large proportion of floral resources produced by OSR during this period may be uncollected. Although there has been extensive work examining OSR nectar and pollen production, no study, to our knowledge, has measured this in relation to the demand by the flower‐visiting insects. Here we quantified the percentage of nectar produced by spring blooming OSR which was uncollected in four OSR fields per year over 2 years. This was achieved by measuring the nectar in both insect accessible and inaccessible (i.e. mesh‐covered) flowers. We also quantified uncollected pollen in flowers at the beginning and the end of anthesis using a haemocytometer. Most of the nectar (69%) and a fifth of pollen (19%) was uncollected in spring blooming OSR. Based on the estimates of nectar production and observed number of insects, nectar supply per insect was estimated at 2204 μL nectar insect−1 h−1, which exceeds potential collection rates by flower‐visiting insects. Given the majority of B. napus is spring blooming, breeding cultivars of OSR which produce more nectar, while not being detrimental to flower‐visiting insects, may be of little conservation benefit. [ABSTRACT FROM AUTHOR]

Managed honey bees play an important role in global crop pollination. Maximizing their potential is likely to be of increasing importance to the human food supply., We explored the potential of waggle dance data to determine the spatial ecology of honey bees sited in a crop under commercial pollination. Over two springs, we video recorded and then decoded 834 waggle dances from colonies located in two apple and pear farms in Kent, U.K. We also obtained pollen samples from returning foragers and quantified the insects visiting apple and pear flowers., The vast majority (84%) of dances were for locations outside of the orchards in which our colonies were located. Accounting for the distance of orchards and oilseed rape fields from the study colonies, the amount of foraging per hectare in oilseed rape fields was greater than in orchards., The results of the present study indicate that maximizing the pollination services of managed honey bee colonies requires an landscape level approach that takes into account farm and foraging scale, as well as competing floral sources. The data also suggest that oilseed rape is a significant competitor to apple and pear flowers for honey bee visits. [ABSTRACT FROM AUTHOR]

Pollinators are in global decline. One of the few ways in which the general public can help is by cultivating ornamental garden plants that attract pollinators by producing nectar, pollen, or both. Advice in the form of lists of recommended plants is available, but how good are these recommendations? Here, we overview a sample of 15 such lists and discuss their strengths and weaknesses. In particular, we found that the range of the number of plant genera per list was large (29–257) and that there was rather little overlap in the recommendations, even among lists addressing the same geographic region (e.g., Britain or North America). Furthermore, the lists often included poor recommendations, omitted many good plants, lacked detail, and were almost invariably based on their authors’ general expertize rather than on empirical data. Nevertheless, some advice given in the lists was good, because these recommendations were presumably backed by personal observations and less formally gathered data. The lists were also very appealing to the public, which makes them an excellent tool in communication and a useful starting point for further research. [ABSTRACT FROM PUBLISHER]

Worker honeybees, Apis mellifera, police each other's reproduction by killing worker-laid eggs. Previous experiments demonstrated that worker policing is effective, killing most (~98%) worker-laid eggs. However, many queen-laid eggs were also killed (~50%) suggesting that effective policing may have high costs. In these previous experiments, eggs were transferred using forceps into test cells, mostly into unrelated discriminator colonies. We measured both the survival of unmanipulated queen-laid eggs and the proportion of removal errors that were rectified by the queen laying a new egg. Across 2 days of the 3-day egg stage, only 9.6% of the queen-laid eggs in drone cells and 4.1% in worker cells were removed in error. When queen-laid eggs were removed from cells, 85% from drone cells and 61% from worker cells were replaced within 3 days. Worker policing in the honeybee has a high benefit to policing workers because workers are more related to the queen's sons (brothers, r p 0.25) than sister workers' sons (0.15). This study shows that worker policing also has a low cost in terms of the killing of queenlaid eggs, as only a small proportion of queen-laid eggs are killed, most of which are rapidly replaced. [ABSTRACT FROM AUTHOR]

Pollinating insects are globally declining, with one of the main causes being the loss of flowers. With the value of countryside reducing, urban areas, particularly gardens, are increasingly recognized as of benefit to wildlife, including flower-visiting insects., Many gardeners specifically select plant varieties attractive to wildlife. Given the wide public interest, many lists of recommended varieties have been produced by both amateurs and professional organizations, but appear not to be well grounded in empirical data. These lists, however, are not without merit and are an obvious starting point. There is clearly a need to put the process onto a firmer footing based more on data and less on opinion and general experience., We collected data over two summers by counting flower-visiting insects as they foraged on 32 popular summer-flowering garden plant varieties in a specially planted experimental garden, with two smaller additional gardens set up in year two to check the generality of the results. With many thousands of plant varieties available to gardeners in the United Kingdom, and other countries or regions, it would have been an impossible task to make a comprehensive survey resulting in a complete and authoritative list., Our results are valuable and encouraging. Garden flowers attractive to the human eye vary enormously, approximately 100-fold, in their attractiveness to insects. Insects, especially bees and hover flies, can be attracted in large numbers with clear differences in the distribution of types attracted by different varieties., Our results clearly show that there is a great scope for making gardens and parks more bee- and insect-friendly by plant selection. Horticulturally modified plant varieties created by plant breeding, including hybrids, are not necessarily less attractive to insects and in some cases are more attractive than their wild-type counterparts. Importantly, all the plants we compared were considered highly attractive to humans, given that they are widely sold as ornamental garden plants., Helping insect pollinators in gardens does not involve extra cost or gardening effort, or loss of aesthetic attractiveness. Furthermore, the methods of quantifying insect-friendliness of plant varieties trialled in this study are relatively simple and can form the basis of further research, including 'citizen science'. [ABSTRACT FROM AUTHOR]

Ivy ( Hedera helix and H. hibernica) is a common autumn-flowering plant found in Europe, North Africa, Macaronesia and Asia. Here, we use five complementary approaches (pollen trapping, nectar refractometry, local and regional surveys of insects foraging on ivy flowers, local survey of ivy abundance) to evaluate its importance to the honey bee ( Apis mellifera) and other flower-visiting insects in Sussex, England., Pollen trapping at six hives in two locations showed that an average 89% of pollen pellets collected by honey bees in the autumn were from ivy., Observations of foraging honey bees on ivy showed that ivy nectar is an even greater target than pollen, as 80% were collecting only nectar. Refractometry of samples from ivy flowers and from honey bees foraging on ivy showed that ivy nectar is rich in sugar, 49% w/w., Surveys showed that the main insect taxa foraging on ivy were honey bees (21%), bumble bees ( Bombus spp., 3%), ivy bees ( Colletes hederae, 3%), common wasps ( Vespula vulgaris, 13%), hover flies (Syrphidae, 27%), other flies (29%) and butterflies (4%). The surveys also showed significant temporal and spatial variation in taxon abundance and proportion., A survey showed that ivy was very abundant on a small scale in both rural and urban areas, being present in 10/10 and 6/10 0.2 × 0.2 km samples within two 4 × 4 km areas respectively., The results show that ivy should probably be considered a keystone species with a high value in the conservation of flower-visiting insects in autumn. [ABSTRACT FROM AUTHOR]

Communication signals often vary between individuals, even when one expects selection to favour accuracy and precision, such as the honey bee waggle dance, where foragers communicate to nestmates the direction and distance to a resource. Although many studies have examined intra-dance variation, or the variation within a dance, less is known about inter-dance variation, or the variation between dances. This is particularly true for distance communication. Here, we trained individually marked bees from three colonies to forage at feeders of known distances and monitored their dances to determine individual communication variation. We found that each honey bee possesses her own calibration: individual duration-distance calibrations varied significantly in both slopes and intercepts. The variation may incur a cost for communication, such that a dancer and recruit may misunderstand the communicated distance by as much as 50%. Future work is needed to understand better the mechanisms and consequences of individual variation in communication. [ABSTRACT FROM AUTHOR]

1. Atta (Hymenoptera: Formicidae) leafcutter ants display the most polymorphic worker caste system in ants, with different sizes specialising in different tasks. The largest workers (majors) have large, powerful mandibles and are mainly associated with colony defence. 2. Majors were observed cutting fallen fruit and this phenomenon was investigated in the field by placing mango fruit near natural Atta laevigata and Atta sexdens colonies in São Paulo State, Brazil. 3. Ants cutting the fruit were significantly heavier (mean = 49.1 mg, SD = 11.1 mg, n= 90) than the ants carrying the fruit back to the nest (mean = 20.9 mg, SD = 9.2 mg, n= 90). 4. Fruit pieces cut by majors were small (mean = 15.9 mg), approximately half the weight of leaf pieces (mean = 28.5 mg) cut and carried by media foragers. It is hypothesised that it is more difficult to cut large pieces from three-dimensional objects, like fruit, compared to two-dimensional objects, like leaves, and that majors, with their longer mandibles, can cut fruit into larger pieces than medias. 5. The study shows both a new role for Atta majors in foraging and a new example of task partitioning in the organisation of foraging. [ABSTRACT FROM AUTHOR]

In many bees, wasps, and ants, workers police each other in order to prevent individual workers from selfishly producing their own male offspring. Although several factors can selectively favor worker policing, genetic relatedness is considered to be of special importance. In particular, kin selection theory predicts that worker policing should be more common in species where workers are more related to the queen's sons than to other workers' sons. Here we provide strong novel support for this theory based on a comparative analysis of policing and male parentage in 109 species of ants, bees, and wasps. First, an analysis of behavioral data confirms that worker policing occurs more frequently in species where workers are more related to the queen's sons than to other workers' sons. Second, an analysis of male parentage shows that a significantly higher percentage of the males are workers' sons in species where the workers are more related to other workers' sons. Both conclusions also hold if data are analyzed using phylogenetically independent contrasts. Although our analysis provides strong overall support for the theory that relatedness affects kin conflict over male parentage, there is also significant residual variation. Several factors that may explain this variation are discussed. [ABSTRACT FROM AUTHOR]

Although best known for cooperation, insect societies also manifest many potential conflicts among individuals. These conflicts involve both direct reproduction by individuals and manipulation of the reproduction of colony members. Here we review five major areas of reproductive conflict in insect societies: (a) sex allocation, (b) queen rearing, (c) male rearing, (d) queen-worker caste fate, and (e) breeding conflicts among totipotent adults. For each area we discuss the basis for conflict (potential conflict), whether conflict is expressed (actual conflict), whose interests prevail (conflict outcome), and the factors that reduce colony-level costs of conflict (conflict resolution), such as factors that cause workers to work rather than to lay eggs. Reproductive conflicts are widespread, sometimes having dramatic effects on the colony. However, three key factors (kinship, coercion, and constraint) typically combine to limit the effects of reproductive conflict and often lead to complete resolution. [ABSTRACT FROM AUTHOR]

abstract: Mutual policing is thought to be important in conflict suppression at all levels of biological organization. In hymenopteran societies (bees, ants, and wasps), multiple mating by queens favors mutual policing of male production among workers (worker polic-ing). However, worker policing of male production is proving to be more widespread than predicted by relatedness patterns, occurring in societies headed by single-mated queens in which, paradoxically, workers are more related to the workers' sons that they kill than the queen's sons that they spare. Here we develop an inclusive-fitness model to show that a second reproductive conflict, the conflict over sex allocation, can explain the evolution of worker policing contrary to relatedness predictions. Among ants, and probably other social Hymenoptera, workers kill males to favor their more related sisters. Importantly, males are killed at the larval stage, presumably because workers cannot determine the sex of queen-laid eggs. Sex-allocation biasing favors worker policing because policing removes some males (the workers' sons) at low cost at the egg stage rather than at higher cost at the larval stage. Our model reveals an important interaction between two reproductive conflicts in which the presence of one conflict (sex allocation) favors the suppression of the other (male production by workers). [ABSTRACT FROM AUTHOR]

Examines the occurrence and adaptive value of leaf caching on foraging trails in the leafcutting ant, Atta colombica. Influence of traffic trail with cache locations on probability of leaf caching; Cache occurrence and relationship to distance along trail; Natural leaf dropping on trails; Efficiency of cache collection.

AbstractIn annual hymenopteran societies headed by a single outbred queen, paternity (determined by queen mating frequency and sperm use) is the sole variable affecting colony kin structure and is therefore a key predictor of colony reproductive characteristics. Here we investigate paternity and male production in five species of Dolichovespula wasps. Twenty workers from each of 10 colonies of each of five species, 1000 workers in total, were analysed at three DNA microsatellite loci to estimate paternity. To examine the relationship between kin structure and reproductive behaviour, worker ovary activation was assessed by dissection and the maternal origin of adult males was assessed by DNA microsatellites. Effective paternity was low in all species (D. media 1.08, D. maculata 1.0, D. sylvestris 1.15, D. norwegica 1.08 and D. saxonica 1.35), leading to the prediction of queen–worker conflict over male production. In support of this, workers with full-size eggs in their ovaries (four out of five species) and adult males that were workers’ sons (all five species) were found in queenright colonies. However, workers were only responsible for a minority of male production (D. media 7.4%, D. maculata 20.9%, D. sylvestris 9.8%, D. norwegica 2.6% and D. saxonica 34.6%) suggesting that the queen maintains considerable reproductive power over the workers. Kin structure and reproductive conflict in Dolichovespula contrast with their sister group Vespula. Dolichovespula is characterized by low paternity, worker reproduction, and queen–worker conflict and Vespula by high paternity, effective worker policing and absence of worker reproduction. The trend revealed by this comparison is as predicted by kin selection theory suggesting that colony kin structure has been pivotal in the evolution of the yellowjacket wasps. [ABSTRACT FROM AUTHOR]

Honeybee (Apis mellifera) colonies rob honey from each other during periods of nectar shortage. Persistent robbing can kill weak colonies. Primarily responsible for preventing robbing are guard bees. Previous research has shown that the probability of both nest mate and non-nest mate workers being accepted by guards at the nest entrance increases as nectar availability increases. The mechanism responsible for this change in guard acceptance can be explained by two competing hypotheses: Odor Convergence and Adaptive Threshold Shift. In this study we tested the Odor Convergence hypothesis. The acceptance by guards at the nest entrance of workers transferred between four colonies that had been fed either odorless sucrose syrup (two colonies) or diluted heather honey (Calluna vulgaris) (two colonies) was measured for 3 days before feeding and during 2 weeks of feeding. Despite the large sample sizes, the probability of guards accepting non-nest mates was not affected by the similarities or dissimilarities in food odor between guards' and non-nest mates' colonies. This finding contrasts with the accepted wisdom that food odors are important in nest mate recognition in honeybees and the data, therefore, strongly reject the Odor Convergence hypothesis. [ABSTRACT FROM PUBLISHER]

AbstractColonies of the European hornet, Vespa crabro, are typically founded by a single queen mated to a single male. From the resulting colony relatedness pattern we predicted strong worker–queen conflict over male production where both the workers and the queen attempt to produce the colony’s males. To test for this conflict, male production was studied in 15 hornet nests using a combination of DNA microsatellite analysis (282 males), worker ovary dissections (500 workers from eight nests) and 50 h of observation (four nests). In contrast to our prediction, the data show that hornet males are queens’ sons, that workers never attempt to lay eggs, rarely have activated ovaries, and that there is no direct aggression between the queen and the workers. This contrasts with other data for vespine wasps, which support relatedness predictions. Dolichovespula arenaria has the same kin structure as V. crabro and workers produce males in many colonies. The similarity between these two species makes it difficult to explain why workers do not reproduce in V. crabro. Self-restraint is expected if worker reproduction significantly reduces colony productivity but there is no obvious reason why this should be important to V. crabro but not to D. arenaria. Alternatively, queen control may be important. The absence of expressed queen–worker conflict rules out physical control. Indirect pheromonal control is a possibility and is supported by the occurrence of royal courts and queen pheromone in Vespa but not Dolichovespula. Pheromonal queen control is considered evolutionarily unstable, but could result from a queen–worker arms race over reproductive control in which the queen is ahead. The genetic data also revealed diploid males in one colony, the first example in the vespine wasps, and two colonies with double matrilines, suggesting that occasional usurpation by spring queens occurs. [ABSTRACT FROM AUTHOR]

The acceptance threshold model predicts that in a fluctuating environment a recognition system should be adaptive rather than fixed. In particular, discriminating individuals, such as guards at a nest entrance, should be less permissive to conspecifics when both the frequency of non-nest-mate contact and the cost of accepting non-nest mates is high. We tested these predictions by studying honey bee guarding during a period in which nectar conditions changed from dearth to abundance. Initially, during nectar dearth, individual guards accepted 80% of introduced nest mates and 25% of non-nest mates. As nectar conditions improved, both the intensity of robbing and guarding and the cost of non-nest-mate acceptance declined. In response, individual guards became more permissive to nest mates and non-nest mates until eventually an “accept-all” threshold occurred—all nest mates and non-nest mates were accepted. These data are consistent with a shifting acceptance threshold and provide the first field data to support the model. A simple linear relationship occurred between the number of guards and the number of fights, 9:1, observed at the hive entrance, suggesting that guarding may be regulated by intruder intensity or otherwise regulated in an adaptive manner. [ABSTRACT FROM PUBLISHER]

Part II. Focuses on a study of task partitioning in social insect societies in regard to the use of queuing delays between foragers and receivers in recruitment in both honeybees and Polybia wasps. Information content and quality of the delays; Use of a stochastic-simulation model in the study; Results and discussion; Conclusion.

Part I. Focuses on a study of task partitioning in insect societies regarding the effect of colony size on the amount of time lost because of queuing delays in direct transfer from foragers to receivers and on colony ergonomic efficiency. Use of a computer simulation model; Results and discussion; Conclusion.

The article presents information on insect societies. Insect societies, too, experience internal conflicts, and research increasingly shows that policing is important to resolve these. Within both human and insect societies, conflicts arise because the interests of individuals differ. In insect societies, conflict revolves around reproduction. Reproducing individuals gain by being more closely related to the young males and queens reared in their colony. By reproducing, society members also exploit the colony and this can be costly. First, uncontrolled reproduction upsets the division of labor between queen and workers and results in a less efficient colony. Second, the offspring reared are often genetically less related and so are less valuable to other society members.

Female mating frequency varies. Determining the causes of this variation is an active research area. We tested the hypothesis that in stingless bees, Meliponini, single mating is due to the execution of queens that make a matched mating at the complementary sex determination locus and have diploid male offspring. We studied the Brazilian species Scaptotrigona depilis. We made up 70 test colonies so that 50% (single matched mating), 25% (double mating), 12.5% (quadruple mating), or 0% (single nonmatched mating) of the emerging brood were diploid males. Queen execution following diploid male emergence was equal and high in colonies producing 50% (77% executed) and 25% (75%) diploid males versus equal and low in colonies producing 12.5% (7%) and 0% (0%) diploid males. These results show that queens that mate with two males with similar paternity suffer an increased chance of being executed, which selects against double mating. However, double mating with unequal paternity (e.g., 25∶75), which occasionally occurs in S. depilis , is selectively neutral. Single mating and double mating with unequal paternity form one adaptive peak. The results show a second adaptive peak at quadruple mating. However, this is inaccessible via gradual evolutionary change in a selective landscape with reduced fitness at double mating. [ABSTRACT FROM AUTHOR]

The article discusses how the worldwide collapse of honey bee (Apis mellifera L.) colonies continues to puzzle researchers and the beekeeping industry. According to the authors, a historical survey suggests that extensive colony losses are not unusual events and have occurred repeatedly over many centuries and in various locations. They suggest that the concern over colony collapse in the U.S. is a result of the honey bees' vital role in U.S. agriculture. Topics include a brief historical overview of colony collapse disorder (CCD) in the U.S., various CCD hypotheses, such as the use of genetically-modified crops, and the impact of pathogenic organisms, such as the ectoparasitic mite Varroa destructor on honey bee colonies.

Asserts that multiple mating of queens of the wasp species Dolichovespula saxonica results in mutual policing by workers. Correlation between worker relatedness and male production by workers; Conclusion that the kinship caused by single mating of the queen may retard social evolution in this species and others like it.

One benefit of group living is vigilance against predators. Previous studies have investigated the group size effect, where individual vigilance decreases as group size increases without reducing the overall ability of the group to detect predators. However, there has been comparatively little research on whether the positioning of individuals can improve the collective vigilance of the group. We studied the coordination of vigilance and its effect on predator detection in the eusocial bee Tetragonisca angustula. Nests are defended by hovering guards that detect and intercept intruders before they reach the nest entrance, in addition to those that stand upon it. We show that hovering guards are positioned nonrandomly, with a strong tendency for equal numbers on both sides of the entrance. This organization increases the collective vigilance of the guard group, as groups distributed in an even ratio, either side of the entrance, have a greater collective field of view than groups that deviate from an even ratio. Finally, we use a bioassay to show that when guards are on both sides of the entrance, their ability to detect intruders before they reach the entrance increases. Overall, our results provide strong evidence that vigilance is coordinated and that this improves nest defense. Although other group-living animals are often selfish in their individual vigilance behaviors and face competing time constraints such as foraging, the altruistic nature of eusocial insect workers has probably facilitated the evolution of coordinated vigilance, as documented here in T. angustula. [ABSTRACT FROM AUTHOR]

Declines in floral resources, pollen and nectar, are considered one cause of pollinator decline. However, the supply and demand of floral resources can vary temporally. In Britain, autumn has been suggested as a period of high floral resource availability due to the flowering of ivy (Hedera helix), a common native plant, combined with fewer insects active during this season. Here, we directly quantified the proportion of pollen and nectar produced by ivy, the primary autumn food source, which is uncollected by the flower‐visiting insect community.We quantified the proportion of nectar produced but uncollected by comparing the mass of nectar sugar accumulated in insect‐accessible versus inaccessible ivy flowers and by surveying the presence of wasted, crystalised, nectar on flowers. Pollen wastage was quantified by comparing pollen counts on anthers at the start of anthesis versus anthers dropped from ivy flowers.Approximately, half the floral resources, 59% nectar and 44% pollen, were uncollected by the flower‐visiting insect community in autumn. As ivy flowers supply most of the available nectar and pollen in autumn, our results show that a large proportion of all floral resources are wasted in autumn.Our results are the first to show that a season can be characterised by a large surplus of floral resources relative to collection by flower‐visiting insects. These results demonstrate the importance of considering seasonal variation in floral resources in the conservation of bees and other flower‐visiting insects. [ABSTRACT FROM AUTHOR]

Cooperation among workers and their seeming altruism result from strict policing by nestmates. [ABSTRACT FROM AUTHOR]

Ornamental flowers commonly grown in urban gardens and parks can be of value to flower-visiting insects. However, there is huge variation in the number of insects attracted among plant varieties. In this study, we quantified the insect attractiveness of 79 varieties in full bloom being grown in a public urban garden that is popular due to its beautiful flowers and other attractions. The results showed very clearly that most varieties (77%, n = 61) were either poorly attractive or completely unattractive to insect flower visitors. Several varieties (19%, n = 15) were moderately attractive, but very few (4%, n = 3) were highly attractive. Closer examination of Dahlia varieties showed that 'open' flowered forms were approximately 20 times more attractive than 'closed' flowered forms. These results strongly suggest that there is a great potential for making urban parks and gardens considerably more bee- and insect-friendly by selecting appropriate varieties. [ABSTRACT FROM AUTHOR]

We examined the effects of reduced mowing on wildflower bloom and flower-visiting insects in the Saltdean Oval, a 6 ha suburban public park in Saltdean, UK., In 2012, a novel management regime was initiated in which approximately half the grass area was left uncut, with the plan being to mow it once per year in autumn. In spring 2013, we set up four blocks, with each block subdivided into four 30 × 5 m strips treated under different mowing regimes: (a) regular mowing every 2 weeks all spring and summer, (b) regular mowing until 2 June, (c) regular mowing until 5 July, and (d) no mowing., The abundance of both flowers and flower-visiting insects increased significantly with reduced mowing, being ca. 3 and 5 times greater in (d) than (a), respectively, with (b) and (c) intermediate. Mowing intensity, however, had a weak effect on wildflower species richness, which was only lower in (a)., A 1 km bee, butterfly, and moth transect walk, 500 m within the long grass part of the park and 500 m within the short, recorded ca. 50× greater insect abundance in the long grass., A questionnaire of public opinion found that 97% of park visitors favoured encouraging insects and wildflowers. In terms of enjoyment of the park, 26% said that it had increased, 64% said that it stayed the same, and 10% said that it decreased., These results present an encouraging example of a potential win-win situation in urban land management change, where the interests of humans and wildlife are aligned, thereby making the goals of conservation easier to achieve. [ABSTRACT FROM AUTHOR]

Social insects often respond to signals and cues from nest-mates, and these responses may include changes in the information they, in turn, transmit. During foraging, Lasius niger deposits a pheromone trail to recruit nestmates, and ants that experience trail crowding deposit pheromone less often. Less studied, however, is the time taken for signalling to revert to baseline levels after conditions have returned to baseline levels. In this paper we study the behaviour of L. niger foragers on a trail in which crowding is simulated by using dummy ants -- black glass beads coated in nestmate cuticular hydrocarbons. Ants were allowed to make four repeat visits to a feeder with dummy ants, and thus crowding, being present on the trail on all visits (CCCC), none (UUUU) or only the first two (CCUU). If dummy ants were always present (CCCC), pheromone deposition probability was low in the first two visits (54% of ants deposited pheromone) and remained low in visits 3 and 4 (51 %). If dummy ants were never present (UUUU) pheromone deposition probability was high in the first two visits (93%) and remained high in visits 3 and 4 (83%). If dummy ants were present on the first two visits but removed on the second two visits (CCUU) pheromone deposition probability was low in the first two visits (61%) but rose in the second two visits (69%). This demonstrates that even after pheromone deposition has been down-regulated due to crowding in the first two visits, it is rapidly up-regulated when crowding is reduced, although it does not immediately return to the base line level. [ABSTRACT FROM AUTHOR]

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

Inclusive fitness benefits depend on recognizing the right individuals to interact with. Social insect nests protect themselves from non-kin intruders through nestmate recognition based on chemical cues. The recognition cues on adult individuals are from a mixture of genetic and environmental sources, but the ontogeny and use of recognition cues on eggs has not been previously assessed. We studied recognition by workers of eggs that were either nestmates or non-nestmates. and the ontogeny of recognition cues on eggs in the ant Formica fusca, a species with precise egg recognition abilities. Workers were able to discriminate among freshly laid eggs with no nest derived cues on them, and the egg surface chemicals varied among nests in these eggs, suggesting that queen derived cues are used in nestmate recognition. The results are discussed in the light of their implications on deceptive social parasite strategies and within colony conflicts. [ABSTRACT FROM AUTHOR]

Honey bees, Apismellifera, face major challenges including diseases and reduced food availability due to agricultural intensification. Additionally, migratory beekeeping may subject colonies to a moving stress, both during the move itself and after the move, from the bees having to forage in a novel environment where they have no knowledge of flower locations. This study investigated the latter. We moved three colonies housed in observation hives onto the campus from a site 26 km away and compared their foraging performance to three similarly sized colonies at the same location that had not been moved. We obtained data on (1) foraging performance by calculating distance by decoding waggle dances, (2) hive foraging rate by counting forager departure rate, (3) forage quality by assessing sugar content of nectar from returning foragers, and (4) forager success by calculating the proportion of bees returning to the nest entrance with nectar in their crop. We repeated this 3 times (August 2010, October 2010, and June 2011) to encompass any seasonal effects. The data show no consistent difference in foraging performance of moved versus resident hives. Overall the results suggest that moving to a new location does not adversely affect the foraging success of honey bees. [ABSTRACT FROM AUTHOR]

In beekeeping, queen honey bees are often temporarily kept alive in cages. We determined the survival of newly-emerged virgin honey bee queens every day for seven days in an experiment that simultaneously investigated three factors: queen cage type (wooden three-hole or plastic), attendant workers (present or absent) and food type (sugar candy, honey, or both). Ten queens were tested in each of the 12 combinations. Queens were reared using standard beekeeping methods (Doolittle/grafting) and emerged from their cells into vials held in an incubator at 34C. All 12 combinations gave high survival (90 or 100%) for three days but only one method (wooden cage, with attendants, honey) gave 100% survival to day seven. Factors affecting queen survival were analysed. Across all combinations, attendant bees significantly increased survival (18% vs. 53%, p<0.001). In addition, there was an interaction between food type and cage type (p<0.001) with the honey and plastic cage combination giving reduced survival. An additional group of queens was reared and held for seven days using the best method, and then directly introduced using smoke into queenless nucleus colonies that had been dequeened five days previously. Acceptance was high (80%, 8/10) showing that this combination is also suitable for preparing queens for introduction into colonies. Having a simple method for keeping newly-emerged virgin queens alive in cages for one week and acceptable for introduction into queenless colonies will be useful in honey bee breeding. In particular, it facilitates the screening of many queens for genetic or phenotypic characteristics when only a small proportion meets the desired criteria. These can then be introduced into queenless hives for natural mating or insemination, both of which take place when queens are one week old. [ABSTRACT FROM AUTHOR]

In social groups composed of kin, inclusive fitness benefits can favor greater cooperation. Alternatively, cooperation can be enforced through the policing of less cooperative individuals. Here, we show that the effect of policing can be twofold: not only can it directly suppress individual selfishness, it can also entirely remove the incentive for individuals to act selfishly in the first place. We term such individual restraint in response to socially imposed policing "acquiescence" and illustrate the concept using examples drawn from the social Hymenoptera (the ants, bees, and wasps). Inclusive fitness models confirm that when a policing system is in place, individuals should be less tempted to act selfishly. This is shown to have important consequences for the resolution of conflict within their societies. For example, it can explain why in many species very few workers attempt to reproduce and why immature females usually do not attempt to develop as queens rather than workers. Although our analyses are primarily focused on the social insects, our conclusions are likely to be general and to apply to other societies as well. [ABSTRACT FROM AUTHOR]

Bramble (Rubus fruticosus L. agg.) is a common summer‐flowering plant native to the United Kingdom. Multiple complementary approaches were used to evaluate its ecological value to the honeybee (Apis mellifera), bumblebees (Bombus spp.) and other flower‐visiting insects in Sussex, England.Regional surveys of insect groups at seven sites across 2 years showed that foraging activity on bramble was dominated by honeybees (60.2%; n = 28 surveys) and bumblebees (17.4%), compared to non‐Apis/Bombus bees (2.8%), hoverflies (Syrphidae, 7.9%), non‐syrphid flies (0.6%), butterflies (6.4%), wasps (0.4%) and beetles (4.4%). Foraging insect community structure was highly similar spatially, but varied significantly between survey months (June and July).In detailed local surveys at one rural and one urban location, there was a diverse range of insect taxa foraging on the bramble flowers, including species of conservation concern (Bombus humilis, Coenonympha pamphilus and Limenitis camilla).Pollen trapping at 12 honeybee hives in four locations showed that an average of 31% of pollen pellets collected by honeybees from late May to early August were bramble, with a peak of 66–86% per location.Bramble was present in 54 out of 60 200 × 200 m randomly selected grid squares surveyed over a large area across Sussex. Plants were recorded in multiple habitat types in both urban and rural areas.Bramble is sometimes considered an undesirable plant or a "thug" that outcompetes other wild flowers; however, these findings confirm that it is highly valuable for flower‐visiting insects. Wherever conflicts of interest and management strategies allow, bramble should be maintained and promoted for wildlife and insect conservation. [ABSTRACT FROM AUTHOR]

One of the major challenges faced by pollinators worldwide is the reduction in their food supply, nectar, and pollen. Given the considerable seasonal variation in the abundance of both floral resources and flower‐visiting insects, conservation initiatives aiming to help pollinators through floral resource supplementation could increase their impacts by targeting periods when the foraging conditions are most difficult. Direct assessment of foraging conditions, however, is extremely labour‐intensive.Here, we compared eight practical measures expected to reflect the foraging difficulty for nectar in the environment. Five measures involved Apis mellifera – an indicator species for the flower‐visitor guild due to its generalist, energetically optimal, and long‐distance foraging habit. These included (i) visitation at feeders with a range of sucrose concentrations, (ii) guarding and (iii) fighting levels at hive entrances, (iv) rates of hive weight changes, and (v) foraging distances encoded in waggle dances. The other measures were (vi–viii) counts of flower‐visiting insects in relation to the rate of nectar sugar secretion in three plant species attractive to flower‐visiting insects.There was considerable, although not complete agreement among the eight measures. Eleven of 28 pairwise correlations were statistically significant. Guarding and fighting correlated with most (five) other measures. We conclude that seven of the eight measures could be potentially useful in gauging seasonal patterns in local foraging conditions, which could help guide targeted conservation initiatives. Assessment of guarding and fighting levels at A. mellifera hive entrances is recommended, as these correlated significantly with most other measures and are easy to obtain in practice. [ABSTRACT FROM AUTHOR]

Pheromone trails are used by many ants to guide foragers between nest and food. But how does a forager that has become displaced from a trail know which way to go on rejoining the trail? A laden forager, for example, should walk towards the nest. Polarized trails would enable ants to choose the appropriate direction, thereby saving time and reducing predation risk. However, previous research has found no evidence that ants can detect polarity from the pheromone trail alone. Pharaoh's ants (Monomorium pharaonis) produce elaborate trail networks throughout their foraging environment. Here we show that by using information from the geometry of trail bifurcations within this network, foragers joining a trail can adaptively reorientate themselves if they initially walk in the wrong direction. The frequency of correct reorientations is maximized when the trail bifurcation angle is approximately 60 degrees, as found in natural networks. These are the first data to demonstrate how ant trails can themselves provide polarity information. They also demonstrate previously unsuspected sophistication in the organization and information content of networks in insect societies. [ABSTRACT FROM AUTHOR]

Honeybees (Apis mellifera) and bumblebees (Bombus spp.) often undergo exploitative competition for shared floral resources, which can alter their foraging behaviour and flower choice, even causing competitive exclusion. This may be strongest in summer, when foraging conditions are most challenging for bees, compared to other times of the year. However, the seasonal dynamics of competition between these major pollinator groups are not well understood. Here, we investigate whether the strength of exploitative competition for nectar between honeybees and bumblebees varies seasonally, and whether competitive pressure is greatest in summer months. We carried out experimental bee exclusion trials from May to late September, using experimental patches of lavender, variety Grosso, in full bloom. In each trial, we compared the numbers of honeybees (HB) foraging on patches from which bumblebees had been manually excluded (bumblebee excluded, BBE) versus control (CON) patches, HB(BBE-CON). This measure of exploitative competition varied significantly with season. As expected, mean HB(BBE-CON) was significantly greater in summer trials than in spring or autumn trials. This was despite high nectar standing crop volumes in BBE patch flowers in spring and autumn trials. Mean HB(BBE-CON) was not different between spring and autumn trials. Our results show that nectar competition between honeybees and bumblebees varies seasonally and is stronger in summer than spring or autumn, adding to current understanding of the seasonality of resource demand and competition between bee species. This information may also help to inform conservation programs aiming to increase floral resources for bees by showing when these resources are most needed. [ABSTRACT FROM AUTHOR]

Hygienic behaviour is a group defence in which dead or diseased individuals are excluded. In the honeybee, Apis mellifera, hygienic behaviour refers to uncapping and removing dead and diseased larvae and pupae from sealed brood cells. We quantified removal of freeze-killed and chalkbrood-infected larvae from open cells in 20 colonies. We also measured removal of freezekilled brood from sealed cells. Study colonies ranged from non-hygienic to fully hygienic (52--100% removal within 2 days). All larvae killed in open cells were removed. This shows that all colonies, including those with low hygienic behaviour against dead brood in sealed cells, are highly hygienic against dead brood in open cells and suggests that low hygienic behaviour against dead brood in sealed cells is a trait in its own right. This may also contribute to understanding why hygienic behaviour is uncommon in A. mellifera, which is puzzling as it reduces several diseases without detrimental effects. In particular, the result provides indirect support for the hypothesis that there are two adaptive peaks conferring disease resistance: (i) high hygienic behaviour: diseased brood are removed quickly, in some cases before becoming infective; (ii) lowhygienic behaviour: diseased brood remain isolated within sealed cells. This article is part of the Theo Murphy meeting issue 'Evolution of pathogen and parasite avoidance behaviours'. [ABSTRACT FROM AUTHOR]

There is growing recognition that the gut microbial community regulates a wide variety of important functions in its animal hosts, including host health. However, the complex interactions between gut microbes and environment are still unclear. Honey bees are ecologically and economically important pollinators that host a core gut microbial community that is thought to be constant across populations. Here, we examined whether the composition of the gut microbial community of honey bees is affected by the environmental landscape the bees are exposed to. We placed honey bee colonies reared under identical conditions in two main landscape types for 6 weeks: either oilseed rape farmland or agricultural farmland distant to fields of flowering oilseed rape. The gut bacterial communities of adult bees from the colonies were then characterized and compared based on amplicon sequencing of the 16S rRNA gene. While previous studies have delineated a characteristic core set of bacteria inhabiting the honey bee gut, our results suggest that the broad environment that bees are exposed to has some influence on the relative abundance of some members of that microbial community. This includes known dominant taxa thought to have functions in nutrition and health. Our results provide evidence for an influence of landscape exposure on honey bee microbial community and highlight the potential effect of exposure to different environmental parameters, such as forage type and neonicotinoid pesticides, on key honey bee gut bacteria. This work emphasizes the complexity of the relationship between the host, its gut bacteria, and the environment and identifies target microbial taxa for functional analyses. [ABSTRACT FROM AUTHOR]

Since 2013, the European Commission has restricted the use of three neonicotinoid insecticides as seed dressings on bee-attractive crops. Such crops represent an important source of forage for bees, which is often scarce in agro-ecosystems. However, this benefit has often been overlooked in the design of previous field studies, leaving the net impact of neonicotinoid treated crops on bees relatively unknown. Here, we determine the combined benefit (forage) and cost (insecticide) of oilseed rape grown from thiamethoxam-treated seeds on Bombus terrestris and Apis mellifera colonies. In April 2014, 36 colonies per species were located adjacent to three large oilseed rape fields (12 colonies per field). Another 36 were in three nearby locations in the same agro-ecosystem, but several kilometers distant from any oilseed rape fields. We found that Bombus colony growth and reproduction were unaffected by location (distant versus adjacent) following the two month flowering period. Apis colony and queen survival were unaffected. However, there was a small, but significant, negative relationship between honey and pollen neonicotinoid contamination and Apis colony weight gain. We hypothesize that any sublethal effects of neonicotinoid seed dressings on Bombus colonies are potentially offset by the additional foraging resources provided. A better understanding of the ecological and agronomic factors underlying neonicotinoid residues is needed to inform evidence-based policy. [ABSTRACT FROM AUTHOR]

Foraging animals must often decide among resources which vary in quality and quantity. Nectar is a resource that exists along a continuum of quality in terms of sugar concentration and is the primary energy source for bees. Alternative sugar sources exist, including fruit juice, which generally has lower energetic value than nectar. We observed many honeybees ( Apis mellifera scutellata) foraging on juice from fallen guava ( Psidium guajava) fruit near others foraging on nectar. To investigate whether fruit and nectar offered contrasting benefits of quality and quantity, we compared honeybee foraging performance on P. guajava fruit versus two wildflowers growing within 50 m, Richardia brasiliensis and Tridax procumbens. Bees gained weight significantly faster on fruit, 2.72 mg/min, than on either flower (0.17 and 0.12 mg/min, respectively). However, the crop sugar concentration of fruit foragers was significantly lower than for either flower (12.4% vs. 37.0% and 22.7%, respectively). Fruit foragers also spent the most time handling and the least time flying, suggesting that fruit juice was energetically inexpensive to collect. We interpret honeybee foraging decisions in the context of existing foraging models and consider how nest-patch distance may be a key factor for central place foragers choosing between resources of contrasting quality and quantity. We also discuss how dilute solutions, such as fruit juice, can help maintain colony sugar-water balance. These results show the benefits of feeding on resources with contrasting quality and quantity and that even low-quality resources have value. [ABSTRACT FROM AUTHOR]

We quantified insect visitation rates by counting how many flowers/inflorescences were probed per unit time for five plant species (four native and one garden: California lilac, bramble, ragwort, wild marjoram, and ivy) growing in Sussex, United Kingdom, by following individual insects (n=2987) from nine functional groups (honey bees (Apis mellifera), bumble bees (Bombus spp.), hoverflies, flies, butterflies, beetles, wasps, non-Apidae bees, and moths). Additionally, we made a census of the insect diversity on the studied plant species. Overall we found that insect groups differed greatly in their rate of flower visits (P<2.2e-16), with bumble bees and honey bees visiting significantly more flowers per time (11.5 and 9.2 flowers/minute, resp.) than the other insect groups. Additionally, we report on a within-group difference in the non-Apidae bees, where the genus Osmia, which is often suggested as an alternative to honey bees as a managed pollinator, was very speedy (13.4 flowers/minute) compared to the other non-Apidae bees (4.3 flowers/minute). Our census showed that the plants attracted a range of insects, with the honey bee as the most abundant visitor (34%). Therefore, rate differences cannot be explained by particular specializations. Lastly, we discuss potential implications of our conclusions for pollination. [ABSTRACT FROM AUTHOR]