Wasp hawking induces endothermic heat production in guard bees.

When vespine wasps, Vespa velutina Lepeletier (Hymenoptera: Vespidae), hawk (capture) bees at their nest entrances alerted and poised guards of Apis cerana cerana F. and Apis mellifera ligustica Spinola (Hymenoptera: Apidae) have average thoracic temperatures slightly above 24° C. Many additional worker bees of A. cerana, but not A. mellifera, are recruited to augment the guard bee cohort and begin wing-shimmering and body-rocking, and the average thoracic temperature rises to 29.8 ± 1.6° C. If the wasps persist hawking, about 30 guard bees of A. cerana that have raised their thoracic temperatures to 31.4 ± 0.9° C strike out at a wasp and form a ball around it. Within about three minutes the core temperature of the heat-balling A. cerana guard bees reaches about 46° C, which is above the lethal limit of the wasps, which are therefore killed. Although guard bees of A. mellifera do not exhibit the serial behavioural and physiological changes of A. cerana, they may also heat-ball hawking wasps. Here, the differences in the sequence of changes in the behaviour and temperature during "resting" and "heat-balling" by A. cerana and A. mellifera are reported.

Dancing to different tunes: heterospecific deciphering of the honeybee waggle dance.

Although the structure of the dance language is very similar among species of honeybees, communication of the distance component of the message varies both intraspecifically and interspecifically. However, it is not known whether different honeybee species would attend interspecific waggle dances and, if so, whether they can decipher such dances. Using mixed-species colonies of Apis cerana and Apis mellifera, we show that, despite internal differences in the structure of the waggle dances of foragers, both species attend, and act on the information encoded in each other's waggle dances but with limited accuracy. These observations indicate that direction and distance communication pre-date speciation in honeybees.

Honeybee (Apis cerana) foraging responses to the toxic honey of Tripterygium hypoglaucum (Celastraceae): changing threshold of nectar acceptability.

To investigate honeybee foraging responses to toxic nectar, honey was collected from Apis cerana colonies in the Yaoan county of Yunnan Province, China, during June, when flowers of Tripterygium hypoglaucum were the main nectar source available. Pollen analysis confirmed the origin of the honey, and high-performance liquid chromatography showed the prominent component triptolide to be present at a concentration of 0.61 mug/g +/- 0.11 SD. In cage tests that used young adult worker bees, significantly more of those provided with a diet of T. hypoglaucum honey mixed with sugar powder (1:1) died within 6 d (68.3%) compared to control groups provided with normal honey mixed with sugar powder (15.8%). Honeybees were trained to visit feeders that contained honey of T. hypoglaucum (toxic honey) as the test group and honey of Vicia sativa or Elsholtzia ciliata as control groups (all honeys diluted 1:3 with water). Bees preferred the feeders with normal honey to those with toxic honey, as shown by significantly higher visiting frequencies and longer imbibition times. However, when the feeder of normal honey was removed, leaving only honey of T. hypoglaucum, the foraging bees returned to the toxic honey after a few seconds of hesitation, and both visiting frequency and imbibition time increased to values previously recorded for normal honey. Toxic honey thus became acceptable to the bees in the absence of other nectar sources.

Bee-hawking by the wasp, Vespa velutina, on the honeybees Apis cerana and A. mellifera.

The vespine wasps, Vespa velutina, specialise in hawking honeybee foragers returning to their nests. We studied their behaviour in China using native Apis cerana and introduced A. mellifera colonies. When the wasps are hawking, A. cerana recruits threefold more guard bees to stave off predation than A. mellifera. The former also utilises wing shimmering as a visual pattern disruption mechanism, which is not shown by A. mellifera. A. cerana foragers halve the time of normal flight needed to dart into the nest entrance, while A. mellifera actually slows down in sashaying flight manoeuvres. V. velutina preferentially hawks A. mellifera foragers when both A. mellifera and A. cerana occur in the same apiary. The pace of wasp-hawking was highest in mid-summer but the frequency of hawking wasps was three times higher at A. mellifera colonies than at the A. cerana colonies. The wasps were taking A. mellifera foragers at a frequency eightfold greater than A. cerana foragers. The final hawking success rates of the wasps were about three times higher for A. mellifera foragers than for A. cerana. The relative success of native A. cerana over European A. mellifera in thwarting predation by the wasp V. velutina is interpreted as the result of co-evolution between the Asian wasp and honeybee, respectively.

Gigantism in honeybees: Apis cerana queens reared in mixed-species colonies.

The development of animals depends on both genetic and environmental effects to a varying extent. Their relative influences can be evaluated in the social insects by raising the intracolonial diversity to an extreme in nests consisting of workers from more than one species. In this study, we studied the effects of mixed honeybee colonies of Apis mellifera and Apis cerana on the rearing of grafted queen larvae of A. cerana. A. mellifera sealed worker brood was introduced into A. cerana colonies and on emergence, the adults were accepted. Then, A. cerana larvae were grafted for queen rearing into two of these mixed-species colonies. Similarly, A. cerana larvae and A. mellifera larvae were also grafted conspecifically as controls. The success rate of A. cerana queen rearing in the test colonies was 64.5%, surpassing all previous attempts at interspecific queen rearing. After emergence, all virgin queens obtained from the three groups (N=90) were measured morphometrically. The A. cerana queens from the mixed-species colonies differed significantly in size and pigmentation from the A. cerana control queens and closely approximated the A. mellifera queens. It is inferred that these changes in the A. cerana queens reared in the mixed-species colonies can be attributed to feeding by heterospecific nurse bees and/or chemical differences in royal jelly. Our data show a strong impact of environment on the development of queens. The results further suggest that in honeybees the cues for brood recognition can be learned by heterospecific workers after eclosion, thereby providing a novel analogy to slave making in ants.

Susceptibility of adult Aethina tumida (Coleoptera: Nitidulidae) to entomopathogenic fungi.

Aethina tumida Murray (Coleoptera: Nitidulidae) is an invasive parasite species in populations of honey bees, Apis mellifera L. Aiming toward substitution of chemical control, we here identified a naturally occurring fungal pathogen of adult A. tumida from its endemic range in South Africa [Metarhizium anisopliae (Metschnikoff) Sorokin variety anisopliae strain FI-203]. The susceptibility of adult beetles (n = 400) to this fungus and to three other generalist entomopathogenic fungal isolates [Metarhizium anisopliae, Beauveria bassiana (Balsamo) Vuillemin, and Hirsutella illustris Minter & Brady] was assessed using spore suspension bioassays. The data revealed significantly increased mortality in the B. bassiana (74.00 +/- 8.94%) and M. anisopliae variety anisopliae (28.00 +/- 16.43%) tests but not in the H. illustris (2.00 +/- 4.47%) and M. anisopliae (12.00 +/- 8.37%) groups. The results indicate a potential for entomopathogenic fungi as an alternative control of A. tumida.

Individual versus social pathway to honeybee worker reproduction (Apis mellifera): pollen or jelly as protein source for oogenesis?

Honeybee workers, Apis mellifera, can reproduce in queenless colonies. The production of queen-like pheromones may be associated with their reproductive activity and induce nestmates to respond by feeding them. Such frequent trophallaxis could supply their protein needs for oogenesis, constituting a social pathway to worker reproduction. However, some individuals can develop ovaries without producing queen pheromones. The consumption of protein-rich pollen could be an alternative solitary pathway for them to satisfy this dietary requirement. In order to investigate the way in which workers obtain proteins for oogenesis, we created orphaned worker groups and determined ovarian and pheromonal development in relation to pollen consumption of selected workers. Individuals that did not consume pollen had significantly more developed ovaries and produced significantly more queen mandibular pheromone than workers that fed directly on pollen. Our results suggest that workers producing queen-like secretions are fed trophallactically. However, reproductive workers that lacked queen pheromones had consumed little or no pollen, suggesting that they also obtained trophallaxis. Although pollen consumption might contribute to sustaining oogenesis, it does not appear to be sufficient. Trophallaxis as a means of obtaining proteins seems to be necessary to attain reproductive status in queenless honeybee colonies.

Heat-balling wasps by honeybees.

Defensiveness of honeybee colonies of Apis cerana and Apis mellifera (actively balling the wasps but reduction of foraging) against predatory wasps, Vespa velutina, and false wasps was assessed. There were significantly more worker bees in balls of the former than latter. Core temperatures in a ball around a live wasp of A. cerana were significantly higher than those of A. mellifera, and also significantly more when exposed to false wasps. Core temperatures of bee balls exposed to false wasps were significantly lower than those exposed to V. velutina for both A. cerana and for A. mellifera. The lethal thermal limits for V. velutina, A. cerana and A. mellifera were significantly different, so that both species of honeybees have a thermal safety factor in heat-killing such wasp predators. During wasps attacks at the hives measured at 3, 6 and 12 min, the numbers of Apis cerana cerana and Apis cerana indica bees continuing to forage were significantly reduced with increased wasp attack time. Tropical lowland A. c. indica reduced foraging rates significantly more than the highland A. c. cerana bees; but, there was no significant effect on foraging by A. mellifera. The latency to recovery of honeybee foraging was significantly greater the longer the duration of wasp attacks. The results show remarkable thermal fine-tuning in a co-evolving predator-prey relationship.

Effects of ethanol and water extracts of propolis (bee glue) on acute inflammatory animal models.

The anti-inflammatory effects of ethanol (EEP) and water (WSD) extracts in ICR mice and Wistar rats were analyzed. Both WSD and EEP exhibited significant anti-inflammatory effects in animal models with respect to thoracic capillary vessel leakage in mice, carrageenan-induced oedema, carrageenan-induced pleurisy, acute lung damage in rats. The mechanisms for the anti-inflammatory effects probably involve decreasing prostaglandin-E(2) (PGE(2)) and nitric oxide (NO) levels. In rats with Freund's complete adjuvant (FCA) induced arthritis, propolis extracts significantly inhibited the increase of interleukin-6 (IL-6) in inflamed tissues, but had no significant effect on levels of interleukin-2 (IL-2) and interferon-gamma (IFN-gamma). The results are consistent with the interpretation that EEP and WSD may exert these effects by inhibiting the activation and differentiation of mononuclear macrophages.

Effects of propolis on blood glucose, blood lipid and free radicals in rats with diabetes mellitus.

The effects of ethanol (EEP) and water (WSD) extracts of propolis collected from north China on blood glucose, blood lipid and free radicals in rats with diabetes mellitus were studied. The results show that EEP and WSD led to decreased levels of blood glucose (FBG), fructosamine (FRU), malonaldehyde (MDA), nitric oxide (NO), nitric oxide synthetase (NOS), total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), very low-density lipoprotein cholesterol (VLDL-C) in serum of fasting rats; and to increased serum levels of high-density lipoprotein cholesterol (HDL-C) and superoxide dismutase (SOD). This suggests that propolis can control blood glucose and modulate the metabolism of glucose and blood lipid, leading to decreased outputs of lipid peroxidation and scavenge the free radicals in rats with diabetes mellitus.

Honeybee combs: construction through a liquid equilibrium process?

Geometrical investigations of honeycombs and speculations on how honeybees measure and construct the hexagons and rhombi of their cells are centuries old. Here we show that honeybees neither have to measure nor construct the highly regular structures of a honeycomb, and that the observed pattern of combs can be parsimoniously explained by wax flowing in liquid equilibrium. The structure of the combs of honeybees results from wax as a thermoplastic building medium, which softens and hardens as a result of increasing and decreasing temperatures. It flows among an array of transient, close-packed cylinders which are actually the self-heated honeybees themselves. The three apparent rhomboids forming the base of each cell do not exist but arise as optical artefacts from looking through semi-transparent combs.

Oviposition by small hive beetles elicits hygienic responses from Cape honeybees.

Two novel behaviours, both adaptations of small hive beetles ( Aethina tumida Murray) and Cape honeybees ( Apis mellifera capensis Esch.), are described. Beetles puncture the sides of empty cells and oviposit under the pupae in adjoining cells. However, bees detect this ruse and remove infested brood (hygienic behaviour), even under such well-disguised conditions. Indeed, bees removed 91% of treatment brood (brood cells with punctured walls caused by beetles) but only 2% of control brood (brood not exposed to beetles). Only 91% of treatment brood actually contained beetle eggs; the data therefore suggest that bees remove only that brood containing beetle eggs and leave uninfected brood alone, even if beetles have accessed (but not oviposited on) the brood. Although this unique oviposition strategy by beetles appears both elusive and adaptive, Cape honeybees are able to detect and remove virtually all of the infested brood.

Prison construction and guarding behaviour by European honeybees is dependent on inmate small hive beetle density.

Increasing small hive beetle (Aethina tumida Murray) density changes prison construction and guarding behaviour in European honeybees (Apis mellifera L.). These changes include more guard bees per imprisoned beetle and the construction of more beetle prisons at the higher beetle density. Despite this, the number of beetles per prison (inmate density) did not change. Beetles solicited food more actively at the higher density and at night. In response, guard bees increased their aggressive behaviour towards beetle prisoners but did not feed beetles more at the higher density. Only 5% of all beetles were found among the combs at the low density but this percentage increased five-fold at the higher one. Successful comb infiltration (and thus reproduction) by beetles is a possible explanation for the significant damage beetles cause to European honeybee colonies in the USA.

Small hive beetles survive in honeybee prisons by behavioural mimicry.

We report the results of a simple experiment to determine whether honeybees feed their small hive beetle nest parasites. Honeybees incarcerate the beetles in cells constructed of plant resins and continually guard them. The longevity of incarcerated beetles greatly exceeds their metabolic reserves. We show that survival of small hive beetles derives from behavioural mimicry by which the beetles induce the bees to feed them trophallactically. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at htpp://dx.doi.org/10.1007/s00114-002-0326-y.

Method of application of tylosin, an antibiotic for American foulbrood control, with effects on small hive beetle (Coleoptera: Nitidulidae) populations.

The method of application of the antibiotic tylosin (Tylan) for control of oxytetracycline-resistant American foulbrood (Paenibacillus larvae White) was tested in honeybee (Apis mellifera L.) colonies. A powdered sugar mixture with tylosin, applied as a dust, was efficacious in eliminating American foulbrood symptoms at a rate of 200-mg Tylan per 20 g of powdered sugar, applied at weekly intervals for 3 weeks. A second method of treatment consisting of Tylan mixed with granulated sugar and vegetable shortening and applied once as a patty, at an equivalent total dose as the dust method, to diseased colonies also effectively eliminated symptoms of disease. In all colonies treated with patties, however, small hive beetle (Aethina tumida Murray) populations significantly increased, compared with the powder sugar method or untreated controls. Bee populations in patty-treated colonies also were significantly reduced, most likely the result of the invasion and proliferation of adult and larval small hive beetles. Such reduction in colony strength was not seen in dust-treated colonies. Because of the obvious damaging populations of small hive beetles, concerns about development of disease resistance, unknown risks of residues, and lack of support by regulatory agencies for the use of the patty method, the use of the dust method of tylosin is greatly favored over the patty method.

Genetic diversity of the honeybee in Africa: microsatellite and mitochondrial data.

A total of 738 colonies from 64 localities along the African continent have been analysed using the DraI RFLP of the COI-COII mitochondrial region. Mitochondrial DNA of African honeybees appears to be composed of three highly divergent lineages. The African lineage previously reported (named A) is present in almost all the localities except those from north-eastern Africa. In this area, two newly described lineages (called O and Y), putatively originating from the Near East, are observed in high proportion. This suggests an important differentiation of Ethiopian and Egyptian honeybees from those of other African areas. The A lineage is also present in high proportion in populations from the Iberian Peninsula and Sicily. Furthermore, eight populations from Morocco, Guinea, Malawi and South Africa have been assayed with six microsatellite loci and compared to a set of eight additional populations from Europe and the Middle East. The African populations display higher genetic variability than European populations at all microsatellite loci studied thus far. This suggests that African populations have larger effective sizes than European ones. According to their microsatellite allele frequencies, the eight African populations cluster together, but are divided in two subgroups. These are the populations from Morocco and those from the other African countries. The populations from southern Europe show very low levels of 'Africanization' at nuclear microsatellite loci. Because nuclear and mitochondrial DNA often display discordant patterns of differentiation in the honeybee, the use of both kinds of markers is preferable when assessing the phylogeography of Apis mellifera and to determine the taxonomic status of the subspecies.

Social encapsulation of beetle parasites by Cape honeybee colonies (Apis mellifera capensis Esch.).

Worker honeybees (Apis mellifera capensis) encapsulate the small hive beetle (Aethina tumida), a nest parasite, in propolis (tree resin collected by the bees). The encapsulation process lasts 1-4 days and the bees have a sophisticated guarding strategy for limiting the escape of beetles during encapsulation. Some encapsulated beetles died (4.9%) and a few escaped (1.6%). Encapsulation has probably evolved because the small hive beetle cannot easily be killed by the bees due to its hard exoskeleton and defensive behaviour.

First approximation to a phenology of the honeybees (Apis mellifera) and flora of Africa.

Peak flowering by the total flora of Africa coincides with or immediately follows peak rainfall. Flowering intensity of the total flora decreases with distance from the equator, but that of the honeybee plant resource base (±2% of total flora) does not. Flowering in the latter is highly synchronous (months 1-5 north of and 9-11 south of the equator). Both total and honeybee flora are completely incongruent with either the biomes or phytochoria of Africa. There is no significant correspondence between honeybee phenology and the total flora but significant correspondence occurs between honeybees and flowering in honeybee plant genera. A logistic regression model reveals that honeybee plant flowering predicts major honeybee colony events with a probability of 0.81 south of the equator and 0.71 for the whole continent. It is postulated that promiscuity in the bee plant genera and honeybees of Africa have contributed to their continental ubiquity.

Fine structure of the homologous tergo-coxal muscles of flying and flightless beetles.

The flight-related tergo-coxal muscles of flying and flightless beetles are compared. In the flying beetle, Pachynoda sinuata, the myofibrils and cylindrical and the myofilaments packed in double hexagonal arrays. The sarcomeres are short (2.8 micrometer) and wide with many large, closely packed adjacent mitochondria but the sarcoplasmic reticulum is poorly developed in this fibrillar (asynchronous) muscle. Sarcoplasmic glycogen in rosette form is abundant. In the flightless beetle, Anthia thoracica, the myofibrils are lamellar-like with sarcomeres of 5.3 micrometer. The myosin filaments form a single hexagonal array each thick filament having an orbital of 11 to 12 thin filaments. The width of the Z-line (120 nm) of A. thoracia muscle was twice that of the Z-line of P. sinuata muscle. The sarcoplasmic reticulum and T-system are well-developed in this afibrillar (synchronous) muscle. Few glycogen granules are present. Triangular projections of the sarcolemma occur regularly opposite the Z-lines in A. thoracica and they appear to extend into the Z-lines. Membranous connections joint adjacent Z-lines in A. thoracica and occasionally in P. sinuata.