Nosema ceranae in European honey bees (Apis mellifera)

Nosema ceranae is a microsporidian parasite described from the Asian honey bee, Apis cerana. The parasite is cross-infective with the European honey bee, Apis mellifera. It is not known when or where N. ceranae first infected European bees, but N. ceranae has probably been infecting European bees for at least two decades. N. ceranae appears to be replacing Nosema apis, at least in some populations of European honey bees. This replacement is an enigma because the spores of the new parasite are less durable than those of N. apis. Virulence data at both the individual bee and at the colony level are conflicting possibly because the impact of this parasite differs in different environments. The recent advancements in N. ceranae genetics, with a draft assembly of the N. ceranae genome available, are discussed and the need for increased research on the impacts of this parasite on European honey bees is emphasized.     

Nosema ceranae in drone honey bees (Apis mellifera)

Nosema ceranae is a microsporidian intracellular parasite of honey bees, Apis mellifera. Previously Nosema apis was thought to be the only cause of nosemosis, but it has recently been proposed that N. ceranae is displacing N. apis. The rapid spread of N. ceranae could be due to additional transmission mechanisms, as well as higher infectivity. We analyzed drones for N. ceranae infections using duplex qPCR with species specific primers and probes. We found that both immature and mature drones are infected with N. ceranae at low levels. This is the first report detecting N. ceranae in immature bees. Our data suggest that because drones are known to drift from their parent hives to other hives, they could provide a means for disease spread within and between apiaries.     

Purification and characterization of beta-glucosidase from honey bees (Apis mellifera)

beta-glucosidase has been purified from the ventriculus and honey sac of Apis mellifera using a combination of anion- and cation-exchange, hydroxyapatite and gel-permeation chromatography. In addition, beta-glucosidase from the hypopharyngeal glands has been partially purified using anion-exchange and gel-permeation chromatography. The purified beta-glucosidase gave a positive result by glycoprotein staining. This beta-glucosidase consists of only one subunit and has M(r) of 72 kDa as determined by SDS-PAGE. IEF-PAGE showed several bands with pIs ranging from 4.5 to 4.8. These multiform proteins have been proposed as having different degrees of glycosylation. The pH optimum of the purified beta-glucosidase from the ventriculus and honey sac are 5.0. These enzymes were stable at temperatures up to 50 degrees C and have a relatively wide pH stability range of 4.0 to 9.0. MALDI-TOF-MS peptide mass maps of purified beta-glucosidase from the ventriculus, honey sac and hypopharyngeal glands showed six matching masses. These results indicate that the beta-glucosidase isolated from the hypopharyngeal glands, honey sac and ventriculus is the same. It is proposed that beta-glucosidase is produced in the hypopharyngeal glands, secreted into the mouth during feeding and then passes to the honey sac. From the honey sac, this enzyme is transferred into honeycomb cells and the ventriculus.     

Effect of pheromones,hormones, and handling on sucrose response thresholds of honey bees (Apis mellifera L.)

The responsiveness of bees to sucrose is an important indicator of honey bee foraging decisions. Correlated with sucrose responsiveness is forage choice behavior, age of first foraging, and conditioned learning response. Pheromones and hormones are significant components in social insect systems associated with the regulation of colony-level and individual foraging behavior. Bees were treated to different exposure regimes of queen and brood pheromones and their sucrose responsiveness measured. Bees reared with queen or brood pheromone were less responsive than controls. Our results suggest responsiveness to sucrose is a physiologically, neuronally mediated response. Orally administered octopamine significantly reduced sucrose response thresholds. Change in response to octopamine was on a time scale of minutes. The greatest separation between octopamine treated and control bees occurred 30 min after feeding. There was no significant sucrose response difference to doses ranging from 0.2 g to 20 g of octopamine. Topically applied methoprene significantly increased sucrose responsiveness. Handling method significantly affected sucrose responsiveness. Bees that were anesthetized by chilling or CO₂ treatment were significantly more responsive than control bees 30 min after handling. Sixty minutes after handling there were no significant treatment differences. We concluded that putative stress effects of handling were blocked by anesthetic.Abbreviations BP brood pheromone - JH juvenile hormone - OA octopamine - PER proboscis extension response - PER-RT proboscis extension response threshold - QMP queen mandibular pheromone     

A modeling approach to swarming in honey bees (Apis mellifera)

Identifying the mechanisms of colony reproduction is essential to understanding the sociobiology of honey bees. Although several proximate causes leading to the initiation of queen rearing – an essential prerequisite to swarming – have been proposed, none have received unequivocal empirical support. Here we model the main proximate hypotheses (colony size, brood comb congestion, and worker age distribution) and show that all proposed swarming triggers occur as a function of the ultimate cause of a colony reaching replacement stability, the point at which the queen has been laying eggs at her maximal rate. We thus present a reproductive optimization model of colony swarming based on evolutionary principles. All models produce results remarkably similar both to each other and to empirically-determined swarming patterns. An examination of the fit between the individual models and swarm-preventing techniques used by beekeepers indicates that the reproductive optimization model has a relatively broad explanatory range. These results suggest that an examination into the behavioral correlates of a queen’s maximum egg laying rate may provide a unified proximate mechanistic trigger leading predictably to colony fission. Generating a predictive model for this very well studied animal is the first step in producing a model of colony fission applicable to other swarm-founding eusocial animals. Received 16 November 2004; revised 31 May 2005; accepted 27 June 2005.     

Octopamine modulates responsiveness to foraging-related stimuli in honey bees (Apis mellifera)

The biogenic amine neurochemical octopamine is involved in the onset of foraging behaviour in honey bees. We tested the hypothesis that octopamine influences honey bee behavioural development by modulating responsiveness to task-related stimuli. We examined the effect of octopamine treatment on responsiveness to brood pheromone (an activator of foraging) and to the presence of older bees in the colony (an inhibitor of foraging in young bees). Octopamine treatment increased responsiveness to brood pheromone and decreased responsiveness to social inhibition. These results identify octopamine both as an important source of variation in response thresholds and as a modulator of pheromonal communication in insect societies. We speculate that octopamine plays more than one role in the organisation of behavioural development indicating a very high level of integration between the neurochemical system and the generation of complex behaviour.     

Odorant moiety and odor mixture perception in free-flying honey bees (Apis mellifera)

Two experiments are described that employ a Y-tube odor-trainingparadigm to address questions relating to olfactory perceptionin free-flying worker honey bees. The first is designed to evaluatehow easily bees can be conditioned to discriminate between twoodors and how willing they are to generalize between closelyrelated odors. In particular, we demonstrate that individualworker bees have no trouble learning to discriminate betweenalkyl ketones or alcohols that differ by only one carbon atom(e.g. heptanone versus octanone) or between a ketone and alcoholfunctional group attached to the same alkyl radical; but theygeneralize between compounds with the same functional groupmuch more readily than those with the same alkyl radical. Thesecond experiment is designed to explore the relationship betweenthe perception of a mixture of odorants and the perception ofthe individual odorants themselves. Our results suggest thatthere appears to be a stronger relationship between a two-odorantmixture and its constituents than would be suggested by themixture being an odor intermediate between the two constituentodorants. We also include a comprehensive discussion on theproblem of extracting quality and concentration informationfrom an odor stimulus and we explore ideas relating to the perceptionof the constituent odorant components of complex odors.     

Hemolymph proteome changes during worker brood development match the biological divergences between western honey bees (Apis mellifera) and eastern honey bees (Apis cerana)

Background

Hemolymph plays key roles in honey bee molecule transport, immune defense, and in monitoring the physiological condition. There is a lack of knowledge regarding how the proteome achieves these biological missions for both the western and eastern honey bees (Apis mellifera and Apis cerana). A time-resolved proteome was compared using two-dimensional electrophoresis-based proteomics to reveal the mechanistic differences by analysis of hemolymph proteome changes between the worker bees of two bee species during the larval to pupal stages.

Results

The brood body weight of Apis mellifera was significantly heavier than that of Apis cerana at each developmental stage. Significantly, different protein expression patterns and metabolic pathways were observed in 74 proteins (166 spots) that were differentially abundant between the two bee species. The function of hemolymph in energy storage, odor communication, and antioxidation is of equal importance for the western and eastern bees, indicated by the enhanced expression of different protein species. However, stronger expression of protein folding, cytoskeletal and developmental proteins, and more highly activated energy producing pathways in western bees suggests that the different bee species have developed unique strategies to match their specific physiology using hemolymph to deliver nutrients and in immune defense.

Conclusions

Our disparate findings constitute a proof-of-concept of molecular details that the ecologically shaped different physiological conditions of different bee species match with the hemolymph proteome during the brood stage. This also provides a starting point for future research on the specific hemolymph proteins or pathways related to the differential phenotypes or physiology.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-563) contains supplementary material, which is available to authorized users.     

Comparison of physicochemical properties and effects of heating regimes on stored Apis mellifera and Apis florea honey

Many of the components, which render honey its specific aroma, flavor, and biological activity, are unstable over time and thermolabile. This study was aimed to compare the chemical composition, effect of heating as well as the time of heat exposure, and storage period on the quality of honey samples from Apis mellifera (A.m.) and Apis florea (A.f.). Methods of the Association of the Official Analytical Chemists (AOAC) were used in this study. The mean values for both A.m. and A.f. honeys were, respectively: moisture (18.5, 13.7%); glucose (35.2, 36.3%); fructose (33.7, 33.8%); sucrose (7.3, 2.9%); invert sugar (68.9, 70.4%); ash (0.26, 1.1%); acidity (51.8, 98.4 meq/kg); pH (3.6, 4.4) and Hydroxy methyl furfural (HMF) (3.78, 3.17 mg/100 g). Honey from A. florea contained less moisture, have higher acidity and ash contents than A. mellifera honey. Significant alterations (P < 0.05) in glucose, fructose, sucrose, and acidity were noticed after six months. Honeys exposed to heating for 15 and 30 min at 50 and 80 °C have shown increased thermo-generated HMF after 15, 30, and 45 days. HMF reached 16.30 ± 1.1 in A. mellifera and 7.41 ± 1.4 mg/100 g in A. florea honeys that exposed for 30 min at 80 °C. Honey from A. florea showed more heat tolerance to thermo-generation of HMF than honey from A. mellifera.     

Choice of flowers by foraging honey bees (Apis mellifera): possible morphological cues

Abstract.

• 1 Honey bees foraging for nectar on lavender (Lavandula stoechas) chose inflorescences with more of their flowers open. The number of open flowers predicted whether an inflorescence was visited by bees, inspected but rejected, or ignored. Inflorescences chosen arbitrarily by observers had numbers of open flowers intermediate between those of visited and ignored inflorescences.
• 2 Differences in morphological characters between types of inflorescence correlated with nectar volume and sugar weight per flower so that visited inflorescences had a disproportionately greater volume of nectar and weight of sugar per flower and greater variance in nectar volume.
• 3 Although there were significant associations between nectar content and the morphological characters of inflorescences, discriminant function analysis revealed discrimination on the basis of morphology rather than nectar content.
• 4 Visited inflorescences tended to have smaller than average flowers but bees tended to probe the largest flowers on visited inflorescences.
• 5 Choice of flowers within inflorescences is explicable in terms of the relationship between flower size and nectar content.

     

Seasonal and task-related variation in free running activity rhythms in honey bees (Apis mellifera)

We measured seasonal variation in the locomotor behavior of newly emerged adult honey bee workers in the laboratory. Analyses of bees from 12 colonies, 7 of which were tested once and 5 tested more than once, revealed seasonal changes in the free-running period (FRP) of the rhythm for locomotor behavior, with an increase from spring to summer. At the same time there was a decrease in the age at onset of circadian rhythmicity. There were no seasonal changes in overall levels of locomotor activity. Temperature and photoperiod, the only factors known to mediate plasticity in the insect clock, cannot account for the observed seasonal variation because bees were maintained under constant conditions. In a second experiment we found no differences in the FRP of nurses and foragers obtained from colonies maintained in a 12 h light: 12 h dark illumination regime. These findings suggest that exposure to unknown cues during preadult stages may affect the circadian behavior of adult bees. Received 7 April 2005; revised 30 August 2005; accepted 1 September 2005.     

梅氏热厉螨寄生对西方蜜蜂生存率和取食量的影响

【目的】梅氏热厉螨Tropilaelapsmercedesae是亚洲地区西方蜜蜂Apismellifera的重要害螨,给我国蜂产业造成巨大损失。该研究主要探究了梅氏热厉螨寄生对西方蜜蜂生存、糖水和花粉取食量及体内病毒变化的影响。【方法】从蜂群中收集被梅氏热厉螨寄生的和未被寄生的新出房蜂,并在室内饲养15 d,统计蜜蜂的存活率。统计蜜蜂每天对糖水和花粉取食量及对总的糖水和花粉取食量。检测7日龄幼虫、新出房蜜蜂和人工饲养15 d的蜜蜂体内BQCV、DWV、VDV-1、ABPV、CBPV、IAPV、SBV和CSBV8种病毒的感染情况。【结果】梅氏热厉螨寄生使蜜蜂对糖水和花粉取食量显著增加,并且寄生显著降低蜜蜂寿命。7日龄蜜蜂幼虫体内均检出DWV;新出房蜂体内均检测到DWV和IAPV;人工饲养15 d的蜜蜂,对照组蜜蜂体内检测到DWV,梅氏热厉螨寄生的蜜蜂体内检测到BQCV、DWV、IAPV和VDV-1病毒。【结论】研究发现,梅氏热厉螨寄生的蜜蜂随着存活时间的增加病毒种类增多。即使梅氏热厉螨寄生未引起某些蜜蜂形态变化,但寄生可能导致体内病毒增加,病毒的复制和免疫反应使蜜蜂能量消耗增多,从而致使蜜蜂寿命缩短。     

Behavior and molecular physiology of nurses of worker and queen larvae in honey bees (Apis mellifera)

In a honey bee colony, worker bees rear a new queen by providing her with a larger cell in which to develop and a large amount of richer food (royal jelly). Royal jelly and worker jelly (fed to developing worker larvae) differ in terms of sugar, vitamin, protein and nucleotide composition. Here we examined whether workers attending queen and worker larvae are separate specialized sub-castes of the nurse bees. We collected nurse bees attending queen larvae (AQL) and worker larvae (AWL) and compared gene expression profiles of hypopharyngeal gland tissues, using Solexa/Illumina digital gene expression tag profiling (DGE). Significant differences in gene expression were found that included a disproportionate number of genes involved in glandular secretion and royal jelly synthesis. However behavioral observations showed that these were not two entirely distinct populations. Nurse workers were observed attending both worker larvae and queen larvae, and there was no evidence of a specialized group of workers that preferentially or exclusively attended developing queens. Nevertheless, AQL attended larvae more frequently compared to AWL, suggesting that nurses sampled attending queen larvae may have been the most active nurses. This study serves as another example of the relationship between differences in gene expression and behavioral specialisation in honey bees.     

Effect of age of worker honey bees (Apis mellifera) on tracheal mite (Acarapis woodi) infestation

The susceptibility of worker honey bees,Apis mellifera L., as a function of age, to infestation by tracheal mites,Acarapis woodi Rennie, was investigated. Bees <24 h old were infested most frequently, and the frequency of infestation declined precipitously thereafter. Bees >4 days old were rarely infested in colonies during active brood rearing. Only 2 of 255 bees >8 days old, and 1 of 246 bees >16 days old, became infested. Most of the eggs found in bees>3 weeks old apparently were produced by the progeny of the original infestation.