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.     

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.

     

Calorimetric investigations of the different castes of honey bees,Apis mellifera carnica

Summary Honey bees of different age and castes were investigated calorimetrically at 20, 25 and 30 °C. Experiments were completed by endoscopic observation of the insects in the visible and the near infrared range and by acoustical monitoring and subsequent frequency analysis of various locomotor activities. Direct calorimetric results of this paper are compared with data of indirect calorimetry from the literature using a respiratory quotient of 1.00 and 21.13 J consumed. Agreements between both methods are generally good. The results show that weight-specific heat production rates increase with age of worker bees by a factor of 5.6 at 30 °C, 3.7 at 25 °C and 40.0 at 20 °C. In groups of foragers the heat production decreases with growing group size to around 6% of the value for an isolated bee. The presence of a fertile queen or of brood reduces the heat output of a small worker group significantly. Adult drones exhibit a much higher metabolic rate (up to 19.7-fold at 20 °C) than juveniles with strong fluctuations in the power-time curves. Fertile queens show a less pronounced heat production rate than virgin queens (54% at 30 °C, 87% at 25 °C and 77% at 20 °C). Calorimetric unrest is much higher for young than for adult queens. Heat production is very low in both uncapped and capped brood and less than 30% of that of a newly emerged worker. In most cases temperature showed a significant influence on the metabolic level, although its sign was not homogeneous between the castes or even within them. Locomotor activities are easily recorded by the acoustic frequency spectrum (0–7.5 kHz) and in good agreement with endoscopic observations and calorimetric traces.Abbreviations RQ respiratory quotient - ww wet weight This paper is part of the PhD thesis of L.F.     

Investigation of gut microbial communities associated with indigenous honey bee (Apis mellifera jemenitica) from two different eco-regions of Saudi Arabia

The microbial communities associated with the alimentary tract of honey bees are very important as they help with food digestion, provide essential nutrients, protect the host from pathogens, detoxify harmful molecules, and increase host immunity. In this study, the structural diversity of the gut microbial communities of native honey bees, Apis mellifera jemenitica from two different geographical regions (Riyadh and Al-Baha) of Saudi Arabia was analyzed by culture-dependent methods and 16S ribosomal RNA (rRNA) gene sequencing. In this study, 100 bacterial isolates were cultivated and phylogenetic analyses grouped them into three phyla: Proteobacteria, Firmicutes, and Actinobacteria. Bacteria in the phylum Proteobacteria were the most dominant (17 species), followed by Firmicutes (13 species) and Actinobacteria (4 species). Some of the identified bacteria (Citrobacter sp., Providencia vermicola, Exiguobacterium acetylicum, and Planomicrobium okeanokoites) were reported for the first time in the genus Apis, while others identified bacteria belonged to the genera Proteus, Enterobacter, Bacillus, Morganella, Lactobacillus, and Fructobacillus. To the best of our knowledge, this is the first study on the gut microbiota of the local honey bees in Saudi Arabia.     

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)]     

Reproduction of Varroa destructor in worker brood of Africanized honey bees (Apis mellifera)

Reproduction and population growth of Varroa destructor was studied in ten naturally infested, Africanized honeybee (AHB) (Apis mellifera) colonies in Yucatan, Mexico. Between February 1997 and January 1998 monthly records of the amount of pollen, honey, sealed worker and drone brood were recorded. In addition, mite infestation levels of adult bees and worker brood and the fecundity of the mites reproducing in worker cells were determined. The mean number of sealed worker brood cells (10,070 ± 1,790) remained fairly constant over the experimental period in each colony. However, the presence and amount of sealed drone brood was very variable. One colony had drone brood for 10 months and another for only 1 month. Both the mean infestation level of worker brood (18.1 ± 8.4%) and adult bees (3.5 ± 1.3%) remained fairly constant over the study period and did not increase rapidly as is normally observed in European honey bees. In fact, the estimated mean number of mites fell from 3,500 in February 1997 to 2,380 in January 1998. In May 2000 the mean mite population in the study colonies was still only 1,821 mites. The fertility level of mites in this study was much higher (83–96%) than in AHB in Brazil(25–57%), and similar to that found in EHB (76–94%). Mite fertility remained high throughout the entire study and was not influenced by the amount of pollen, honey or worker brood in the colonies. This revised version was published online in July 2006 with corrections to the Cover Date.     

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.     

Population demography of Australian feral bees (Apis mellifera)

Honey-bees are widespread as feral animals in Australia. Their impact on Australian ecosystems is difficult to assess, but may include competition with native fauna for floral resources or nesting sites, or inadequate or inappropriate pollination of native flora. In this 3-year study we examined the demography of the feral bee population in the riparian woodland of Wyperfeld National Park in north-west Victoria. The population is very large but varied considerably in size (50–150 colonies/km²) during the study period (1992–1995). The expected colony lifespan for an established colony is 6.6 years, that for a founder colony (new swarm), 2.7 years. The population is expected to be stable if each colony produces 0.75 swarms per year, which is less than the number predicted on the basis of other studies (2–3 swarms/colony per year). Therefore, the population has considerable capacity for increase. Most colony deaths occurred in the summer, possibly due to high temperatures and lack of water. Colonies showed considerable spatial aggregation, agreeing with earlier findings. When all colonies were eradicated from two 5-ha sites, the average rate of re-occupation was 15 colonies/km² per year. Ten swarms of commercial origin were released and were found to have similar survival rates to founder colonies. However, the feral population is self-sustaining, and does not require immigration from the domestic population. Received: 2 September 1996 / Accepted: 26 March 1997     

Thermoregulation of water collecting honey bees (Apis mellifera)

Honey bees (Apis mellifera carnica, Apidae, Hymenoptera) visited a pond in order to collect water. During their stays at the pond the body surface temperature of water foragers was measured using contactless thermography. Irrespective of the ambient temperature (T(A)) which ranged from 13.6 to 27.2 degrees C, the water carriers reached thoracic temperatures of 36-38.8 degrees C (mean values of the measuring periods). The maximum thoracic value of an individual bee was 44.5 degrees C. At higher T(A) (20.9-27.2 degrees C) head and abdomen were only about 3 degrees C and 2 degrees C on the average higher than the surroundings, respectively. In the lower range of T(A) (13.6-16.6 degrees C), however, the bees warmed their heads up to 29.2 degrees C (13 degrees C above T(A)) and the abdomen up to 23.3 degrees C (7.1 degrees C above T(A); mean values of the measuring periods).The head and abdomen were even provided independently of one another with heat from the thorax. At a higher T(A) only little heat came from the heated thorax into the abdomen, at a cooler T(A) (13.6-16.6 degrees C) more heat reached the abdomen. In all probability, at a higher T(A) only a small amount of haemolymph was pumped from the thorax into the abdomen; the most warm blood probably circulated in the head-thorax area. The average duration of stays at the pond decreased linearly from 110 to 42 s with rising T(A). Head and thorax showed great fluctuations of temperature. For example, the head was heated by 4.6 degrees C within 25 s, the thorax by 6.1 degrees C within 30 s.Foragers drinking sucrose solution are known to increase their thoracic temperature with rising concentration of the sucrose solution. The water foragers had thoracic temperatures similar to that of bees feeding on 0.5 molar sucrose solution. It is hypothesized that the foraging motivation of both groups was similar and therefore they regulated their thoraces at the same temperature level.     

Tactile learning and the individual evaluation of the reward in honey bees (Apis mellifera L.)

Using the proboscis extension response we conditioned pollen and nectar foragers of the honey bee (Apis mellifera L.) to tactile patterns under laboratory conditions. Pollen foragers demonstrated better acquisition, extinction, and reversal learning than nectar foragers. We tested whether the known differences in response thresholds to sucrose between pollen and nectar foragers could explain the observed differences in learning and found that nectar foragers with low response thresholds performed better during acquisition and extinction than ones with higher thresholds. Conditioning pollen and nectar foragers with similar response thresholds did not yield differences in their learning performance. These results suggest that differences in the learning performance of pollen and nectar foragers are a consequence of differences in their perception of sucrose. Furthermore, we analysed the effect which the perception of sucrose reward has on associative learning. Nectar foragers with uniform low response thresholds were conditioned using varying concentrations of sucrose. We found significant positive correlations between the concentrations of the sucrose rewards and the performance during acquisition and extinction. The results are summarised in a model which describes the relationships between learning performance, response threshold to sucrose, concentration of sucrose and the number of rewards. Accepted: 14 April 1999     

Seasonality of salt foraging in honey bees (Apis mellifera)

1. Honey bees (Apis mellifera) prefer foraging at compound‐rich, ‘dirty’, water sources over clean water sources. As a honey bee's main floral diet only contains trace amounts of micronutrients – likely not enough to sustain an entire colony – it was hypothesised that honey bees forage in dirty water for physiologically essential minerals that their floral diet, and thus the colony, may lack. 2. While there are many studies regarding macronutrient requirements of honey bees, few investigate micronutrient needs. For this study, from 2013 to 2015, a series of preference assays were conducted in both summer and autumn. 3. During all field seasons, honey bees exhibited a strong preference for sodium in comparison to deionised water. There was, however, a notable switch in preferences for other minerals between seasons. 4. Calcium, magnesium, and potassium – three minerals most commonly found in pollen – were preferred in autumn when pollen was scarce, but were avoided in summer when pollen was abundant. Thus, as floral resources change in distribution and abundance, honey bees similarly change their water‐foraging preferences. 5. Our data suggest that, although they are generalists with relatively few gustatory receptor genes, honey bee foragers are fine‐tuned to search for micronutrients. This ability likely helps the foragers in their search for a balanced diet for the colony as a whole.     

The microRNA ame-miR-279a regulates sucrose responsiveness of forager honey bees (Apis mellifera)

Increasing evidence demonstrates that microRNAs (miRNA) play an important role in the regulation of animal behaviours. Honey bees (Apis mellifera) are eusocial insects, with honey bee workers displaying age-dependent behavioural maturation. Many different miRNAs have been implicated in the change of behaviours in honey bees and ame-miR-279a was previously shown to be more highly expressed in nurse bee heads than in those of foragers. However, it was not clear whether this difference in expression was associated with age or task performance. Here we show that ame-miR-279a shows significantly higher expression in the brains of nurse bees relative to forager bees regardless of their ages, and that ame-miR-279a is primarily localized in the Kenyon cells of the mushroom body in both foragers and nurses. Overexpression of ame-miR-279a attenuates the sucrose responsiveness of foragers, while its absence enhances their sucrose responsiveness. Lastly, we determined that ame-miR-279a directly target the mRNA of Mblk-1. These findings suggest that ame-miR-279a plays important roles in regulating honey bee division of labour.     

The relationship between comb age and performance of honey bee (Apis mellifera) colonies

A study on the relationship between the age of comb and the activity of the hybrid Carniolan honey bee colonies in collecting pollen activity, worker brood production, colony strength, and honey yield was conducted. In comparison to colonies with combs aged 4-years, colonies with combs aged 1, 2 and 3-years significantly exceeded in the number returning workers, number returning workers with pollen loads, rate of storing pollen, rate of worker brood production, and size of colony population. Colonies with combs aged 1, 2 and 3-years produced significantly more honey than colonies with combs aged 4-years (5.25, 4.90 and 4.65 kg/colony vs. 4.45 kg/colony, respectively). It can be concluded that the foraging rate, gathering and storing pollen, brood production, colony population size, and honey yield significantly depended on the age of combs. Beekeepers can replace old combs with new ones to increase brood and honey production.     

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.     

Phylogenetic analysis of Starmerella apis in honey bees (Apis mellifera)

Honey bees are among the most effective pollinators that promote plant reproduction. Bees are highly active in the pollen collection season, which can lead to the transmission of selected pathogens between colonies. The clade Starmerella comprises yeasts that are isolated mainly from bees and their environment. When visiting plants, bees can come into contact with Starmerella spp. The aim of this study was to determine the prevalence and phylogenetic position of S. apis in bee colonies. Bee colonies were collected from nine apiaries in three regions. Ten colonies were sampled randomly from each apiary, and pooled samples were collected from the central part of the hive in each colony. A total of 90 (100%) bee colonies from nine apiaries were examined. Starmerella apis was detected in 31 (34.44%) samples, but related species were not identified. The 18S rRNA amplicon sequences of S. apis were compatible with the GenBank sequences of Starmerella spp. from India, Japan, Syria, Thailand, and the USA. The amplicon sequences of S. apis were also 99.06% homologous with the sequences deposited in GenBank under accession numbers JX515988 and NG067631 .This is the first study to perform a phylogenetic analysis of S. apis in Polish honey bees.