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.     

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.     

Regulation of nectar collection in relation to honey storage levels by honey bees, Apis mellifera

Honey bees collect distinct nutrient sources in the form ofnectar (energy) and pollen (nitrogen). We investigated the effectof varying energy stores on nectar and pollen foraging. We foundno significant changes in nectar foraging in response to changesin honey storage levels within colonies. Individual foragersdid not vary activity rates or nectar load sizes in responseto changes in honey stores, and colonies did not increase nectarintake rates when honey stores within the hive were decreased.This result contrasts with pollen foraging behavior, which isextremely sensitive to colony state. Our data show that individualforaging decisions during nectar collection and colony regulationof nectar intake are distincdy different from pollen foraging.The behavior of honey bees illustrates that foraging strategy(and therefore foraging models) can incorporate multiple currencies,including both energy and protein intake.[Behav Ecol 7: 286–291(1996)]     

Foraging profits and thoracic temperature of honey bees (Apis mellifera)

Summary Body temperature and duration of foraging activities were affected by the concentration of sucrose solution imbibed. When experienced foragers of Apis mellifera arrived at a gravity feeder from the hive, thoracic temperature (T_TH) was independent of sucrose concentration (X = 36.3 °C). While imbibing 40% and 60% (g solute per g of solution) solutions bees maintained T_TH at approximately the same high level as upon arrival, but those imbibing 10%, 20%, and 30% solutions regulated T_TH lower (X = 33.5 °C). All bees departed the feeder for the hive at the same T_TH (X = 36.1 °C). Bees that imbibed 40% and 60% solutions sometimes immediately took flight after imbibition and averaged less than 15 s to takeoff. Time to takeoff was 2–3 times longer for bees that had imbibed 10% and 20% solutions because warmup preceded takeoff. The rate of energy expenditure at T_TH=36.3°C (at 40% and 60% solutions) was 20% greater than that at 33.3°C (at 10%, 20%, and 30% solution). Bees that fed on the highly concentrated solutions regulated T_TH so that rate of net energy gain was enhanced, but bees that fed on less concentrated solutions could have increased rate of net gain by maintaining a higher T_TH which would have reduced time required for takeoff. The latter bees lowered rate of expenditure of their limited energetic costs and thereby lowered short-term net profits in favor of improved long-term contribution to the colony.Abbreviations T _A ambient temperature - T _TH thoracic temperature     

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.     

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.     

Genetic bases of tolerance to Varroa destructor in honey bees (Apis mellifera L.)

Currently, the Varroa destructor mite is the most serious parasite of honey bees (Apis mellifera) and has become a nearly cosmopolitan species. The mite not only causes damage by feeding on the haemolymph of honey bees, but it also transmits viruses, which have been implicated in colony collapse disorder. The major research goal has been to breed mite-tolerant honey bee lines in order to reduce the amount of pesticide used, because pesticides can promote the evolution of resistance in mites. In this review, we describe different behavioural traits and genes that may be part of the defence against the Varroa mite. Specifically, we review grooming behaviour, Varroa-sensitive hygiene and the suppression of mite reproduction. A large number of candidate genes have been identified by Quantitative Trait Loci studies, and through gene expression studies their function and effect have been elucidated. Results from the studies discussed can be used in apiary practice.     

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.     

Genotypic variation in susceptibility of honey bees (Apis mellifera) to infestation by tracheal mites (Acarapis woodi)

Two-way selection for lines of honey bees (Apis mellifera L.) susceptible and resistant to infestation by tracheal mites (Acarapis woodi Rennie) was conducted for two generations. Individuals of the susceptible line were 1.4 and 2.4 times more likely to become infested by female mites after the first and second generations, respectively. These results demonstrate that genotypic variability exsts within North American populations and that selection for resistance is feasible. The mechanisms of resistance are unknown.     

A honey bee (Apis mellifera) light phase response curve

The authors report a phase response curve (PRC) for individual honey bees (Apis mellifera) to single 1-h light pulses (1000 lux) using an Aschoff Type 1 protocol (n = 134). The bee PRC is a weak (Type 1) PRC with a maximum advance of 1.5 h between circadian time (CT) 18 and 3 and a maximum delay of 1.5 h between CT 12 and 18. This is the first published honey bee light PRC and provides an important resource for chronobiologists and honey bee researchers. It may also have practical applications for what is an economically important species frequently transported across different time zones.     

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.