Heritable allometric variation in bumble bees: opportunities for colony-level selection of foraging ability

Different characters of an organism may be correlated if genes control the allometric relationship between them. If genetic variation exists for such genes then the allometric relation itself is potentially subject to change by selection. In social insects allometric relations represent colony-level characters. If colonies differ in these relations and this variation leads to differential productivity among colonies, then selection on allometric relations can operate at the level of the colony. We assessed the extent of heritable, between-colony variation for the allometric coefficients relating proboscis ( = glossa) length to wing length for two bumble bee species (Bombus huntii and B. occidentalis). We found that in both species colonies did not differ significantly in slope (b) but did differ significantly in intercept (a) of the regression of glossa length on wing length. Within-colony variation of the intercept was estimated by randomly constituting groups of five workers from each colony and calculating the regression for each group. The intraclass correlation was then calculated from the between- and within-colony mean squares. We found significant intraclass correlations in both species, giving heritabilities of 0.5 ± 0.3 in B. hunti and 0.7 ± 0.3 in B. occidentalis. If this allometric relation affects colony foraging success and foraging environments vary geographically, then the intercept should exhibit corresponding geographic variation. We tested this prediction by comparing intercepts calculated using wild-caught B. vagans workers from Alberta, Ontario and Maine. We found that the intercepts did differ significantly between sites, with the bees from Alberta having a significantly smaller intercept than the bees from eastern North America. Our results illustrate the opportunity for selection on an allometric relation that directly affects the foraging success of individual bumble bee colonies.     

A Change in Orientation: Recognition of Rotated Patterns by Bumble Bees

In three experiments, bumble bees were trained to discriminate between a reinforcing pattern (S+) and a nonreinforcing one (S–) which differed only in the configuration of four artificial petals. They were subsequently tested for recognition of the S+ rotated by 90° (S + 90). Experiment 1 used petals of four colors, and the other experiments used four symbols. The symbols either remained unchanged when the whole pattern was rotated (e.g., + in Experiment 2) or changed appearance (e.g., < in Experiment 3). The bees failed to recognize the S + 90 in the first two experiments, but in Experiment 3, the choice proportion for S + 90 in the presence of a New pattern was significantly higher than chance. Bumble bees can recognize a rotated pattern, possibly by using mental rotation, provided that a cue as to the extent of the pattern transformation is given.     

The effect of workers size frequency distribution on colony development inBombus terrestris

Summary The effect of workers size frequency distribution on colony development was studied in 12 young colonies ofB. terrestris. By replacing the original workers with workers of determined size, colonies constituting small, large or mixed size nursing workers were created. The nursing workers size frequency distribution did not influence the average size of the newly emerged workers, nor their size frequency distribution. In contrast, the number of emerging workers and number of egg cells constructed by the queen in colonies with large workers were higher than in colonies with small workers. The small number of emerging workers is explained by prolonged duration of larval time in response to sub-optimal feeding in colonies of small workers. The higher number of egg cells constructed by the queens is supposed to be in response to the number of new cocoons available, or to better condition of the brood.     

Monoandry and polyandry in bumble bees (Hymenoptera; Bombinae) as evidenced by highly variable microsatellites

Highly variable microsatellites enabled a precise assessment of the number of queen matings in the colonies of five bumble bee species. Fifteen of the sixteen microsatellites initially cloned from B. terrestris had flanking regions similar enough to allow PCR amplification on the other Bombus species analysed. The microsatellites selected for intracolony study (four per species) were characterized by a high heterozygosity (0.58–0.93) and a large number of alleles (3–18) in the local populations from which the colonies originated. A single male appeared to have inseminated the queens in the colonies of four species, B. terrestris, B. lucorum, B. lapidarius and B. pratorum, which belong to three subgenera, whereas two of the three analysed colonies of B. hypnorum were polyandrous (minimum number of two and four patrilines, respectively).     

云南澜沧江流域传粉昆虫——熊蜂多样性现状与保护对策

本文对澜沧江流域内热带地区的勐腊县、亚热带地区的南涧县和寒温带地区的德钦县3个低、中、高海拔地带的重要传粉昆虫——熊蜂属(Bombus)的多样性现状进行了观察研究,并与20年前的资料进行了比较分析。结果得出：20多年以来,由于植被人为的破坏严重,传粉昆虫的自然生存环境发生了较大的改变,致使3个不同地带的传粉昆虫一部分物种消失,一部分物种的群体减少,而少数原来极少采到或者未采到的物种和种群则成为优势群体。从而得出：在云南省澜沧江流域人为的生境改变,对传粉昆虫的物种多样性影响极大,要保护或者恢复传粉昆虫的种群,首要任务是保护和恢复生态系统。     

Insect antimicrobial peptides show potentiating functional interactions against Gram-negative bacteria

Antimicrobial peptides (AMPs) and proteins are important components of innateimmunity against pathogens in insects. The production of AMPs is costly owing toresource-based trade-offs, and strategies maximizing the efficacy of AMPs at lowconcentrations are therefore likely to be advantageous. Here, we show thepotentiating functional interaction of co-occurring insect AMPs (the bumblebeelinear peptides hymenoptaecin and abaecin) resulting in more potentantimicrobial effects at low concentrations. Abaecin displayed no detectableactivity against Escherichia coli when tested alone atconcentrations of up to 200 μM, whereas hymenoptaecin affected bacterialcell growth and viability but only at concentrations greater than 2 μM.In combination, as little as 1.25 μM abaecin enhanced the bactericidaleffects of hymenoptaecin. To understand these potentiating functionalinteractions, we investigated their mechanisms of action using atomic forcemicroscopy and fluorescence resonance energy transfer-based quenching assays.Abaecin was found to reduce the minimal inhibitory concentration ofhymenoptaecin and to interact with the bacterial chaperone DnaK (anevolutionarily conserved central organizer of the bacterial chaperone network)when the membrane was compromised by hymenoptaecin. These naturally occurringpotentiating interactions suggest that combinations of AMPs could be usedtherapeutically against Gram-negative bacterial pathogens that have acquiredresistance to common antibiotics.     

蜜蜂及熊蜂微孢子虫rRNA基因研究

核糖体RNA(rRNA)是一种理想的进化计时器,已广泛地应用于研究微生物的系统发育和进化关系。蜜蜂和熊蜂都被微孢子虫感染,关于蜜蜂和熊蜂微孢子虫rRNA基因研究主要有rRNA基因序列的测定分析、二级结构的研究和用rRNA基因检测诊断微孢子虫等。这些对蜜蜂和熊蜂微孢子虫系统发育的研究和微孢子虫的防治等具有重要的推动作用。     

Foraging dynamics of bumble bees: correlates of movements within and between plant species

What rules determine whether bumble bees continue exploitingplants of the species just visited or switch to another species?To tackle this question, we recorded handling times and flighttimes from bees foraging in a natural meadow containing fiveplant species. Inter- and intra-specific plant distances werequantified. The bee-subjective colors of the five species weredetermined; two of these species had similar colors and structures,while three species were distinct from all others. The followingrules were identified: (1) The decision to switch species wascorrelated with previous flower handling time, which we assumeis a function of the reward amount received at the flower. Aftershort handling times, the probability of switching to anotherspecies increased, whereas it decreased after long handlingtimes. This difference became even greater if the bee had hada run of several short or several long handling times. (2) Constantflights (those between flowers of the same species) and transitionflights (those between flowers of different species) followedstereotyped temporal patterns independent of the distances betweenflowers. Constant flights within five plant species consistentlyhad median durations of about 2 seconds, whereas median transitiontimes between species took 3–6 seconds. (3) This temporalrule broke down, however, if the flowers of two species hadsimilar colors, in which case transition flights had equal dynamicsas constant flights. (4) Bees switched more frequently fromrare than from common species but even more frequently betweensimilar species. We conclude that the bees' choices were determinedby a set of rules that guided them to stay with the currentplant species as long as flowers were rewarding and availablewithin close distance but to switch to another species if flowersoffered low rewards or were not encountered at close range     

A STUDY ON PHYLOGENETIC RELATIONSHIPS AMONG THE SUB-GENERA OF BUMBLE BEES (HYMENOPTERA:APIDAE)

Abstract Phylogenetic relationships among the 28 subgenera of bumble bees were studied by using morphological and behavioral characters. The results suggest that the traditional Bombus Latreille and Psithyrus Lepeletier are monophyletic groups. However, the position of Mendacibombus in cladograms is different from that of the traditional view. In addition, according to their geographical distribution and relative relationships Eurasian—Asian group and Eurasian—American group are recognized for Bombus Latreille.     

熊蜂族系统发育关系的研究(膜翅目:蜜蜂总科)(英文)

本文选取熊蜂雌雄外部形态特征、行为学特征,对熊蜂28个亚属之间的系统发育关系利用支序分析的方法进行了探讨。研究结果表明传统的熊蜂属与拟熊蜂属是两个单系群,Mendacibombus亚属在支序图中的位置与传统看法有所不同。另外,根据能蜂各亚属间的亲缘关系及它们的地理分布建议熊蜂属中分两个亚属群：欧亚—亚洲群与欧亚—美洲群。     

Estimation of bumblebee queen dispersal distances using sibship reconstruction method

Dispersal ability is a key determinant of the propensity of an organism to cope with habitat fragmentation and climate change. Here we quantify queen dispersal in two common bumblebee species in an arable landscape. Dispersal was measured by taking DNA samples from workers in the spring and summer, and from queens in the following spring, at 14 sites across a landscape. The queens captured in the spring must be full sisters of workers that were foraging in the previous year. A range of sibship reconstruction methods were compared using simulated data sets including or no genotyping errors. The program Colony gave the most accurate reconstruction and was used for our analysis of queen dispersal. Comparison of queen dispersion with worker foraging distances was used to take into account an expected low level of false identification of sister pairs which might otherwise lead to overestimates of dispersal. Our data show that Bombus pascuorum and B. lapidarius queens can disperse by at least 3 and 5 km, respectively. These estimates are consistent with inferences drawn from studies of population structuring in common and rare bumblebee species, and suggest that regular gene flow over several kilometres due to queen dispersal are likely to be sufficient to maintain genetic cohesion of ubiquitous species over large spatial scales whereas rare bumblebee species appear unable to regularly disperse over distances greater than 10 km. Our results have clear implications for conservation strategies for this important pollinator group, particularly when attempting to conserve fragmented populations.