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PubMed1990

Epidemiology of honey bee parasites.

The epidemiology of honey bee parasites has been somewhat neglected, but Lynn Royce and Philippe Rossignol describe their unique characteristics. Indeed, it appears that a parasite of social insects has in essence to adapt to two hosts: first, the individual worker within a colony, the numbers of which grow linearly and second, to the colony itself, the actual reproductive 'organism'. Transmission also has vertical and horizontal components. Analysis of tracheal mite populations in particular suggests that intracolony parasite levels are regulated by the swarming behavior of their hosts. Ironically, current and highly productive methods of honey bee management with movable hives curb swarming and may contribute to increasing the spread and the impact of some parasites. This insight may result in changing management practices to reduce the detrimental effects of bee parasites.

Journal Article↗
PubMed2001

Juvenile hormone levels in honey bee (Apis mellifera L.) foragers: foraging experience and diurnal variation.

A rising blood titer of juvenile hormone (JH) in adult worker honey bees is associated with the shift from working in the hive to foraging. We determined whether the JH increase occurs in anticipation of foraging or whether it is a result of actual foraging experience and/or diurnal changes in exposure to sunlight. We recorded all foraging flights of tagged bees observed at a feeder in a large outdoor flight cage. We measured JH from bees that had taken 1, 3-5, or >100 foraging flights and foragers of indeterminate experience leaving or entering the hive. To study diurnal variation in JH, we sampled foragers every 6h over one day. Titers of JH in foragers were high relative to nurses as in previous studies, suggesting that conditions in the flight cage had no effect on the relationship between foraging behavior and JH. Titers of JH in foragers showed no significant effects of foraging experience, but did show significant diurnal variation. Our results indicate that the high titer of JH in foragers anticipates the onset of foraging and is not affected by foraging experience, but is modulated diurnally.

Journal Article↗
PubMed1998

Queen mandibular gland pheromone influences worker honey bee (Apis mellifera L.) foraging ontogeny and juvenile hormone titers.

SYNTHETIC QUEEN MANDIBULAR GLAND PHEROMONE (QMP) WAS APPLIED TO HONEY BEE COLONIES TO TEST TWO HYPOTHESES: (i) QMP acts like a primer pheromone in the regulation of age-related division of labor, and (ii) this primer effect, if present, varies in three strains of workers that show genetically-based differences in their retinue attraction response to QMP (a pheromone releaser effect). Strains of workers that were high, or low in their response to QMP in a laboratory bioassay, as well as unselected 'wild-type' workers, were fostered in queenright colonies with or without supplemental QMP. Effects of QMP on foraging ontogeny and juvenile hormone III (JH) blood titers in worker honey bees were measured. Bees in QMP-supplemented colonies showed significant delays in foraging ontogeny, and foraging activity was reduced. They also had significantly lower JH titers, although the titer curves were somewhat atypical. There were no differences in foraging ontogeny or JH titers among the three strains. We conclude that (i) QMP can delay the ontogeny of foraging by some mechanism that suppresses JH production, (ii) this QMP primer response is independent of the retinue releaser response, and (iii) QMP can play an important role in regulating division of labour.

Journal Article↗
PubMed1999

Haemolymph sugars and the control of the proventriculus in the honey bee Apis mellifera.

Crop emptying and rectal filling rates were investigated in bees trained to collect defined amounts of sucrose solution. Crop emptying rates strongly depended on the sucrose concentration of the collected solution. There was a close match between the energy expenditure of the bees and the amount of sucrose transported through the proventriculus, irrespective of the fluid dilution. Results indicated that the controlling variable was the amount of sucrose flowing through the proventriculus rather than the volume flow. In order to distinguish between haemolymph osmolality and haemolymph carbohydrate levels as factors controlling the activity of the proventriculus, bees were injected with either metabolizable or non-metabolizable carbohydrates. Only the injection of metabolizable carbohydrates modulated the activity of the proventriculus, indicating that the titers of metabolizable carbohydrates are involved in the feedback loop controlling crop emptying, and that haemolymph osmolality alone does not influence the activity of the proventriculus.

Journal Article↗
PubMed2000

Effect of an amino acid on feeding preferences and learning behavior in the honey bee, Apis mellifera.

Amino acids are common constituents of floral nectars and can be critical components in the diets of insect pollinators. Yet the means through which insects detect amino acids can be complex and arise from pre- and post-ingestive mechanisms. Furthermore, the response to an amino acid can change depending on an insect's nutritional status. Here we use a sensitive feeding assay and Proboscis Extension Response (PER) conditioning in the honey bee to assay the effect of glycine, which is a common constituent of nectars and pollens. Subjects preferred to feed on a sucrose stimulus that contained glycine, and the highest relative preference was recorded for the highest concentration of glycine. However, the highest response rate occurred at lower than maximal concentrations and differed depending on the physiological status of the subjects. These results are consistent with a model in which subjects attempt to maintain a physiological target amount of glycine/amino acid relative to other nutrients. All concentrations of glycine enhanced the rate and magnitude of a conditioned response to an odor in the PER assay, which demonstrates that animals can learn to modify their responses to an odor conditioned stimulus based on the presence of amino acid. This capability would enhance a honey bee's ability to evaluate the quality of floral nectars, which are associated with, among other things, odor cues given off by flowers. In future studies these techniques will allow us to evaluate the physiological roles that amino acids play in honey bee diet and choice behavior.

Journal Article↗
PubMed2000

Ecdysteroid titer, ovary status, and dominance in adult worker and queen bumble bees (Bombus terrestris).

The role of ecdysteroids in the regulation of dominance and reproduction in social Hymenoptera is little explored. In the current study we compared ecdysteroid titers in hemolymph of individual queen and worker bumble bees (Bombus terrestris) that differ in their behavior, reproductive status and social environment. Egg-laying queens that head colonies and have ovaries exhibiting all stages of follicle development, had a higher ecdysteroid titer than virgin queens whose ovaries contained only follicles at initial stages. In workers, the relationship between ecdysteroid titers and follicle development appears to be more complex and to be influenced by the bee's social status and social environment. Shortly after emergence, young workers had only follicles at the initial stages of oogenesis and they exhibited a low ecdysteroid titer. No significant correlation was detected between ovary status and ecdysteroid titer in workers, with some workers showing activated ovaries but low ecdysteroid titers. However, at six days of age, a trend towards higher ecdysteroid titer was observed for workers in queenless groups, a condition characterized by rapid follicle development relative to queenright conditions. In these queenless groups, high social status was associated with high ecdysteroid titers. By contrast, in queenright workers ecdysteroid titers were low, even for bees with presumably high social status that had activated ovaries and were observed performing oviposition behavior. This study suggests that ecdysteroids are involved in regulation of reproduction in B. terrestris.

Journal Article↗
PubMed1985

Flower petal microtexture is a tactile cue for bees.

Honeybees are shown to be able to detect, learn, and discriminate between microsculptured epidermes of flower petals. The sensilla trichodea at the tips of the bees' antennae are in the same size range as the microsculptural features of the petals (ca. 10 mum), which presumably deflect these mechanoreceptive sensilla in characteristic ways. Honeybees were trained to associate reward with one floral texture and to choose that over another. Further, the bees also recognized differences in textures at different ends of petals of the same species. The phenomenon is significant in that it suggests another way in which insect pollinators can discriminate between the flowers of different plant species and so act as species isolators. Also, the microsculptural patterns differ from one end of a petal to the other and, therefore, can be used as nectar-guides by foraging bees. This study presents a previously unreported conditioned response to texture by insects and shows the functional significance of a floral character used in plant taxonomy.

Journal Article↗
PubMed2000

Detection of antimicrobials in bee products with activity against viridans streptococci.

OBJECTIVES: Bee products have been studied extensively for their healing properties and have become part of cosmetic preparations and folk medicine. The major objective of this study was to examine the presence of antimicrobials in various bee products. DESIGN: Propolis, honeycomb lids, pollen, honeycombs, and honey were screened for antimicrobial compounds. Viridans streptococci were used as indicator strains. Ethanol extracts were applied onto paper disks, dried, and put on the surface of nutrient agar plates with the overlay containing viridans streptococci. The plates were then incubated and evaluated the next day for the presence of inhibition zones. The size of the inhibition zone represented a quantitative measure of antimicrobial activity in a sample. Thin-layer chromatography was used for separation of compounds in the samples and biodetection-an overlay with indicator strain-identified the antimicrobial compounds by formation of inhibition zones. RESULTS: Ethanol extracts of propolis and honeycomb lids, as well as honey containing honeycomb lids contained a mixture of antimicrobial compounds in various amounts. Thin-layer chromatography experiments with two different solvent systems differing in polarity suggested that major antimicrobials present in the samples prepared from honeycomb lids, honeycombs, pollen, and propolis have similar properties. These active compounds were not extremely hydrophobic. CONCLUSIONS: Extracts from the tested samples of bee products exhibited antimicrobial properties at various levels depending on the sample and bacterial species used for testing. Using chromatographic techniques, we demonstrated similar properties of the active compounds in various active samples. In conclusion, our results suggest that honey containing honeycomb lids may be a beneficial food supplement because of the presence of antibacterial compounds.

Animals↗
PubMed2005

Plant Origin of Green Propolis: Bee Behavior, Plant Anatomy and Chemistry.

Propolis, a honeybee product, has gained popularity as a food and alternative medicine. Its constituents have been shown to exert pharmacological effects, such as anti-microbial, anti-inflammatory and anticancer. Shoot apices of Baccharis dracunculifolia (alecrim plant, Asteraceae) have been pointed out as sources of resin for green propolis. The present work aimed (i) to observe the collecting behavior of bees, (ii) to test the efficacy of histological analysis in studies of propolis botanical origin and (iii) to compare the chemistries of alecrim apices, resin masses and green propolis. Bee behavior was observed, and resin and propolis were microscopically analyzed by inclusion in methacrylate. Ethanol extracts of shoot apices, resin and propolis were analyzed by gas chromatography/mass spectroscopy. Bees cut small fragments from alecrim apices, manipulate and place the resulting mass in the corbiculae. Fragments were detected in propolis and identified as alecrim vestiges by detection of alecrim structures. Prenylated and non-prenylated phenylpropanoids, terpenoids and compounds from other classes were identified. Compounds so far unreported for propolis were identified, including anthracene derivatives. Some compounds were found in propolis and resin mass, but not in shoot apices. Differences were detected between male and female apices and, among apices, resin and propolis. Alecrim apices are resin sources for green propolis. Chemical composition of alecrim apices seems to vary independently of season and phenology. Probably, green propolis composition is more complex and unpredictable than previously assumed.

Journal Article↗
PubMed1999

The role of stingless bees in crop pollination.

Stingless bees (Apidae: Meliponini) are common visitors to flowering plants in the tropics, but evidence for their importance and effectiveness as crop pollinators is lacking for most plant species. They are known to visit the flowers of approximately 90 crop species. They were confirmed to be effective and important pollinators of 9 species. They may make a contribution to the pollination of approximately 60 other species, but there is insufficient information to determine their overall effectiveness or importance. They have been recorded from another 20 crops, but other evidence suggests that they do not have an important role because these plants are pollinated by other means. The strengths and limitations of stingless bees as crop pollinators are discussed. Aspects of their biology that impact on their potential for crop pollination are reviewed, including generalized flower visiting behavior of colonies, floral constancy of individual bees, flight range, and the importance of natural vegetation for maintaining local populations.

Journal Article↗
PubMed2001

Acute Sarcocystis falcatula-like infection in a carmine bee-eater (Merops nubicus) and immunohistochemical cross reactivity between Sarcocystis falcatula and Sarcocystis neurona.

An unidentified Sarcocystis falcatula-like infection was diagnosed in a captive bee-eater (Merops nubicus) in a zoo in Florida. The bird died suddenly, probably due to protozoa-associated pneumonia. Protozoal schizonts were found in lungs and heart, and immature sarcocysts were seen in skeletal muscles. Ultrastructurally, schizonts were located in capillary endothelium and merozoites lacked rhoptries, consistent with the structure of Sarcocystis species. Sarcocysts were immature, microscopic, and contained only metrocytes. The sarcocyst wall had finger-like villar protrusions that were up to 0.7 microm long and up to 0.2 microm wide. The villar protrusions lacked microtubules, characteristically seen in sarcocysts of S. falcatula. Antigenically, parasites in lungs and muscles of the bee-eater reacted with a varying intensity with polyclonal rabbit antisera to S. falcatula and Sarcocystis neurona. Results indicated that sarcocysts in the bee-eater were morphologically different from the reported structure for sarcocysts of other S. falcatula infections.

Acute Disease↗
PubMed1973

Continuous, fixed-ratio, and fixed-interval reinforcement in honey bees.

Bees learned to enter a Plexiglas tube and to suck small portions of sugar solution; every entry or every fifth entry was reinforced. During an extinction phase, the bees on the fixed-ratio schedule emitted twice as many responses as did those given continuous reinforcement. Bees on a fixed-interval schedule of reinforcement emitted lower response rates than did those given fixed-ratio reinforcement. By extending the conditioning procedure for several days, it was possible to maintain responding with fixed-ratio schedules requiring 30 responses per reinforcement and with fixed-interval values up to 90 sec. Under fixed-interval schedules, response rates did not increase toward the end of the reinforcement intervals.

Journal Article↗
PubMed2000

Analysis of phospholipase A2 glycosylation patterns from venom of individual bees by capillary electrophoresis/electrospray ionization mass spectrometry using an ion trap mass spectrometer.

A method based on tryptic digestion, ultrafiltration and capillary electrophoresis/mass spectrometry (CE/MS) has been developed for the analysis of the glycosylation pattern in the phospholipase A2 (PLA) of individual honeybees. Without reducing the disulfide bonds, PLA was digested with trypsin and filtered with a 3 kDa molecular weight (MW) cut-off membrane. With this procedure, the glycopeptides could be isolated from the nonglycosylated peptides. After tryptic digestion and ultrafiltration, the disulfide bonds were reduced before analysis by CE. To reduce the adsorption, CE separation was performed on successive multiple ionic-polymer (SMIL) polybrene (PB) coated capillary columns. The SMIL-PB columns allowed partial separation of the glycopeptides and eight glycopeptides were identified by on-line coupling of CE with electrospray ionization (ESI) mass spectrometry. The analysis of phospholipase A2 from the venom of individual bees indicated that the variation and relative abundances of different glycopeptides were similar between the younger and the older bees.

Aging↗
PubMed1994

Regulation of IgE and IgG4 responses by allergen specific T-cell clones to bee venom phospholipase A2 in vitro.

An in vitro antibody response to bee venom phospholipase A2 (PLA) from peripheral blood mononuclear cells of bee sting-sensitized individuals was achieved after stimulation with PLA and pokeweed mitogen. This stimulation resulted in a secretion of TH1-associated cytokines and induced PLA-specific and nonspecific IgG4 antibody production but not IgE production. The addition of interleukin-4 (IL-4) to this system decreased the secretion of IgG antibodies, whereas secretion of polyspecific IgE was induced. The mitogen was not required if peripheral blood mononuclear cells were enriched with autologous, PLA-specific, resting T-cell clones in the presence of the antigen. In these experiments the cytokine profile of the particular clone determined the antibody class generated. Low ratios of IL-4 to interferon-gamma, induced by the antigen alone or obtained by neutralizing anti-IL-4 antibodies, enhanced IgG4 antibody formation, whereas IgE levels increased at high ratios of IL-4 to interferon-gamma. These results suggest a complementary regulation of the main isotypes, IgE and IgG4, implicated in allergic and protective hyperimmune responses.

Animals↗
PubMed2006

Molecular cloning and expression of icarapin, a novel IgE-binding bee venom protein.

The 1045bp full-length cDNA sequence of a new bee venom component was obtained by rapid amplification of cDNA ends. The 672bp coding sequence corresponds to a protein with a signal peptide and multiple carbohydrate binding sites, and it was named icarapin. It has the new consensus sequence N-[TS]-T-S-[TV]-x-K-[VI](2)-[DN]-G-H-x-V-x-I-N-[ED]-T-x-Y-x-[DHK]-x(2,6)- [STA]-[VLFI]-x-[KR]-V-R-[VLI]-[IV]-[DN]-V-x-P. At least two transcript variants were found. Recombinant icarapin was tested for recognition by IgE antibodies and gave a positive dot blot with sera from 4 out of 5 bee venom allergic patients, all beekeepers. Indirect immunofluorescent staining localized the protein in the cuticular lining of the venom duct.

Amino Acid Sequence↗
PubMed1990

Phospholipase A2 in venom extracts from honey bees (Apis mellifera L.) of different ages.

We measured phospholipase A2 activity in the venom of worker honey bees (Apis mellifera L.) of known ages using chemical (titrimetric) and radioallergosorbent methods. The two techniques give similar results. Low levels of phospholipase A2 are present in the venom system at the time of eclosion. Phospholipase A2 activity in the venom increases steadily through the 10 days after eclosion. Maximal phospholipase A2 levels (about 40 micrograms phospholipase A2/venom sac) are maintained through the rest of the life of a worker bee in summer.

Aging↗
PubMed1992

Mapping human T cell epitopes on phospholipase A2: the major bee-venom allergen.

Phospholipase A2 (PLA2), the major bee-venom allergen, was purified by gel filtration, inactivated by denaturing, and carboxymethylating its cysteine residues. Peripheral blood mononuclear cells from an individual (HLA-DR2 [15], Dw52, DQ1 and DQ3) allergic to bee stings were used to generate cell lines specific for PLA2 and a control antigen, tetanus toxoid. These lines were 90% CD3+, 64% CD4+ and 20% CD8+ by fluorocytometry analysis. T-lymphocyte epitope mapping done with 12 overlapping synthetic peptides of PLA2 revealed two immunodominant epitopes. These epitopes correspond to amino acid sequences 50 to 69 and 83 to 97 of PLA2. Cytokine interleukin-4 and Interferon-gamma secretion was studied from PLA2- and tetanus toxoid-specific cell lines. Interleukin-4 secretion was common to both cell lines but only tetanus-toxoid cell lines secreted interferon-gamma. No interferon-gamma was found to be secreted by PLA2-specific cell line in response to stimulation by PLA2 or the two immunodominant peptides.

Allergens↗
PubMed2002

Analysis of N-glycosylation of phospholipase A2 from venom of individual bees by microbore high-performance liquid chromatography-electrospray mass spectrometry using an ion trap mass spectrometer.

The N-linked oligosaccharides were released from the phospholipase A2 (PLA) with glycopeptidases and reductively aminated with the chromophore, p-aminobenzoic acid ethyl ester (ABEE). The ABEE-labeled oligosaccharides were separated by microbore high-performance liquid chromatography (micro-HPLC) using a reversed-phase column and analyzed by electrospray mass spectrometry. Differentiation between alpha-1,3 and alpha-1,6 core-fucosylated glycans was achieved by comparison the glycans released by glycopeptidases peptide-N-glycanase A (PNase A) and peptide-N-glycanase F (PNase F). All N-linked oligosaccharides except 3B and 3C could be identified in this approach. The analysis of PLA oligosaccharides from the venom of individual bees indicated that glycosylation patterns between the younger and the older bees were similar.

Animals↗