The Western honeybees Apis mellifera carnica and A. m. ligustica are closely related subspecies living in neighbouring regions. Metabolism and the upper lethal thermal limits are crucial physiological traits, adapted in the evolutionary process to environment and climate conditions. We investigated whether samples from these two ecotypes differ in these traits. The standard metabolic rate was higher in the A. m. ligustica population only at a high temperature (T
a ~ 40 °C; dVCO2 = 12 nl s−1; P < 0.05), probably due to a higher body temperature (dTthorax = 1.5 °C; P < 0.01). The critical thermal maximum of activity and respiration was similar (difference activity CTmax = 0.8 °C, respiratory CTmax = 1.1 °C). The lethal temperature (LT50, 8h) revealed higher tolerance and survival rates of the Ligustica bees (Carnica 50.3 °C; Ligustica 51.7 °C; P < 0.02). Results reveal the adaptation of the two subspecies to their historic climate conditions, possibly favouring Ligustica in a warming environment.
Social evolution has influenced every aspect of contemporary honey bee biology, but the details are difficult to reconstruct. The reproductive ground plan hypothesis of social evolution proposes that central regulators of the gonotropic cycle of solitary insects have been coopted to coordinate social complexity in honey bees, such as the division of labor among workers. The predicted trait associations between reproductive physiology and social behavior have been identified in the context of the pollen hoarding syndrome, a larger suite of interrelated traits. The genetic architecture of this syndrome is characterized by a partially overlapping genetic architecture with several consistent, pleiotropic QTL. Despite these central QTL and an integrated hormonal regulation, separate aspects of the pollen hoarding syndrome may evolve independently due to peripheral QTL and additionally segregating genetic variance. The characterization of the pollen hoarding syndrome has also demonstrated that this syndrome involves many non-behavioral traits, which may be the case for numerous "behavioral" syndromes. Furthermore, the genetic architecture of the pollen hoarding syndrome has implications for breeding programs for improving honey health and other desirable traits: If these traits are comparable to the pollen hoarding syndrome, consistent pleiotropic QTL will enable marker assisted selection, while sufficient additional genetic variation may permit the dissociation of trade-offs for efficient multiple trait selection.
In addition to honeybee workers, drones also contribute to colonial thermoregulation. We show the drones' contribution to thermoregulation at 5 different experimental temperatures ranging from 15-34 °C. The frequency and the degree of endothermy depended on the drones' local ambient temperature and age. Location on brood or non-brood areas had no influence. The frequency of endothermic drones and the intensity of endothermy increased with decreasing temperature. 30% of drones of 8 days and older heated their thorax by more than 1 °C above the abdomen. The youngest drones (0-2 days) did not exceed this level of endothermy. Though young drones were less often engaged in active heat production, their contribution to brood warming was not insignificant because their abundance on the brood nest was 3.5 times higher than that of the oldest drones (≥13 days). Results suggest that the stimulus for the drones' increased frequency of heating at low experimental temperatures was their low local ambient air and/or comb temperature.
To identify candidate microRNAs involved in post-transcriptional regulation of brain (region)-selective gene expression in
the adult honeybee brain, we isolated eight microRNAs: seven known microRNAs, ame-mir-2-1, −8, 13a, −34, −276, −317, −1000, and one novel one, named mir-hbd, that has significant sequence similarity with
the Drosophila dme-mir-11. Among them, ame-mir-1000 and −276 were expressed in a brain-selective and -preferential manner, respectively, in workers and drones. In particular,
ame-mir-276-expression was enriched in the optic lobes and in the small type-Kenyon cells of the mushroom bodies in the nurse
bee, forager, queen, and drone brains. Almost all predicted targets of amemir-1000 and −276 encode neural function related genes, suggesting the involvement in neural function of both microRNAs.
–honey bee–gene expression
The detection of honey adulteration with invert sugar syrups from various C3 and C4 plant sources was realized by coupling an isotope ratio mass spectrometer both to an elemental analyzer and to a liquid Chromatograph (EA/LC-IRMS). For 451 authentic honeys measured, the individual δ13C values of bulk honey, its protein fraction, fructose, glucose, and di- and trisaccharides ranged from −22.5 to −28.2‰ and did not show differences (Δδ13C) of more than ± 0.9‰ (average), with a maximum standard deviation of 0.7‰ The Δδ13C (fructose — glucose) value was significantly lower (0 ± 0.3‰). Based on the obtained results and considering a confidence level of 99.7%, the following limits for Δδ13C values of authentic honey are proposed: Δδ13C max.: ± 2.1‰ (maximum difference between all measured δ13C values); Δδ13C fru —glu: ± 1.0‰; Δδ13C (‰) protein — honey: ⩾ − 1.0‰ The newly developed EA/LC-IRMS method and the purity criteria defined represent a significant improvement compared to existing methods.
Phylogeographic and morphometric evidence can be used to cluster Apis mellifera subspecies into evolutionary lineages or branches. Mitochondrial DNA sequence and restriction site analyses have shown similar clustering of subspecies groups. Thus, mtDNA variation can be used to infer honey bee evolutionary relationships. In this paper, we describe three 16S mtDNA PCR-RFLP patterns, each one completely associated with a previously determined A, M, or C Dra I restriction pattern of the COI-COII region. These results indicate that the COI-COII and the 16S genes have had a very closely linked evolutionary history. Although distinct patterns were obtained with Eco RI, Alu I, Hinc II and Taq I, the best differentiation among the three patterns was observed with Dra I and Vsp I enzymes. Nucleotide sequence analysis of the 16S gene fragment displayed 10 sites of base substitution (1.35%) among the three patterns and two insertions in the A. m. scutellata pattern.
Until now, all reports state that during eversion of the drone endophallus, two substances are ejected, viz. semen and mucus, and that the mating sign of a queen bee consists of the bulb of the endophallus filled with mucus. I examined substances ejected during eversion of drone endophalli, as well as substances present in the mating sign. In the fully everted endophallus, creamy semen was found near the chitinized plates, amorphous white mucus was located further distally and a transparent-whitish condensed substance appeared at the end of the everted endophallus. In mating signs, white mucus was found near the bursa copulatrix of the queens and a transparent-whitish condensed substance in the distal part of the sign. Microscopic examinations showed that the transparent-whitish substance consisted of fragments of epithelial membranes sloughed from mucus glands. Thus, not two substances, but three, viz. semen, mucus and epithelial membranes, are ejected during endophallus eversion and natural mating with queen bees.
Red clover is a key floral ressource for bumblebees (Bombus spp.). We here investigate variation within and among red clover fields in species richness and abundance of Bombus spp. in addition to Apis mellifera. Bumblebee individuals were grouped into the following functional groups, based on castes and tongue length: (1) all queens, (2) all workers, (3) short-tongued workers and (4) long-tongued workers. In 14 study fields, no spatial or diurnal within-field differences were found in abundances of bee groups. However, seasonal differences were detected. On average 6.3±0.6 Bombus spp. were observed in each field. In general, maximum observed bee abundances of a field were not associated with field size, weediness, or presence of commercial honeybee hives. However, long-tongued bumblebee abundance was significantly lower in fields with beehives. Seed yield was marginally higher in less weedy fields, but not significantly augmented by presence of bee hives.
It is assumed that oil bees in the tribe Centridini and oil flowers in the family Malpighiaceae have a conservative evolutionary
association, and it is postulated that they also have a tight ecological relationship. Here, we test the hypothesis that variations
in the availability of Malpighiaceae flowers affect the abundance and richness of centridine bees. We measured oil availability
and sampled bees on oil flowers of Byrsonima sericea DC. (Malpighiaceae) in 12 localities (habitats), along the Northeastern Brazilian Atlantic coast. The availability of floral
oil was strongly correlated with richness and abundance of centridine bees. In contrast, no significant correlation was observed
between abundance and richness of centridine bees after excluding the effect of oil abundance. We proposed that the asymmetry
of density dependence is determining the observed pattern of regional diversity for centridine bees.
Keywordsbee diversity–Centridini–floral oil–habitat quality–Malpighiaceae
Tropilaelaps mite samples were collected from 72 locations in 25 provinces throughout China. The mitochondrial DNA cox1 and ribosomal ITS1-5.8S-ITS2 fragments of Tropilaelaps mites were surveyed for sequence variation or the presence or absence of specific restriction sites that differentiate four
species of Tropilaelaps mite (Tropilaelaps clareae, Tropilaelaps mercedesae, Tropilaelaps koenigerum, and Tropilaelaps thaii). Based on these identified diagnostic characters, all samples in this study corresponded to T. mercedesae, which has been mistaken for T. clareae until now. None of the other Tropilaelaps species were found infesting Apis mellifera in China. A total of 73 cox1 haplotypes and 104 ITS1-5.8S-ITS2 haplotypes were discovered in this study. Haplotype analysis revealed that there is no
association between geographic distance and genetic distance among populations. The results of the present study clarified
the taxonomic status and biogeography of Tropilaelaps mites in China, and should have implications for the control and bee quarantine efforts in China.
Solitary bees of the genus Tetrapedia have a specific association with mites of the genus Roubikia (Chaetodactylidae). These mites are frequently found attached to active Tetrapedia bees. We quantified the number of mites on individuals of Tetrapedia diversipes Klug and examined the interaction between these species. Nests of T. diversipes were obtained from trap-nests placed in four localities in São Paulo, Brazil. The study lasted from March 2007 to February
2009. Out of a total of 650 nests with emergences, 118 were infested with mites (Roubikia sp.). From these nests, 176 individuals of T. diversipes emerged with mites on their bodies. Additionally, six individuals of Coelioxoides waltheriae, the specific kleptoparasitic bee to T. diversipes, emerged. Mites were attached mainly to the mesosoma. All nests infected with mites did not presented mortality of the immature.
The mortality rate of nests was inversely related to the level of mite infestation, suggesting a mutualistic interaction in
which mites may remove fungi from the nests, while the bees would provide the mites with transport, dispersal, and shelter.
Keywordssolitary bee–phoresy–trap-nest–Atlantic Forest–symbiosis
A total of 382 bumblebee specimens were examined: Bombus atratus (n = 310), Bombus morio (n = 42), Bombus bellicosus (n = 16), Bombus opifex (n = 8), and Bombus tucumanus (n = 6). Prevalence, abundance, and intensity of mite infestation for each Bombus species and for each caste were recorded. The different mite species infesting bumblebee specimens were: Kuzinia laevis (Dujardin), Kuzinia americana (Delfinado and Baker), Scutacarus acarorum (Goeze), Pneumolaelaps longanalis (Hunter and Husband), Pneumolaelaps longipilus (Hunter), Tyrophagus putrescentiae (Schrank), and Parasitellus fucorum (De Geer). Numbers of mites varied enormously and ranged from one individual to over 200 per bumblebee. Kuzinia mites were represented by the phoretic forms (hypopi). Only nymphs of P. fucorum were recorded. Only female mites were recorded for the other mite species. Tyrophagus putrescientiae, P. longipilus, S. acarorum, and P. fucorum were less abundant, while K. laevis, K. americana, and P. longanalis were the most abundant. These records of T. putrescientiae, P. fucorum, K. laevis, K. americana, P. longipilus, and S. acarorum are the first for Argentine bumblebees.
Certain phenolic acids and flavonoids are described in the literature as marker substances for several unifloral honeys. As not all authors utilised the same methods for extraction and determination, there are remarkable discrepancies in the published data concerning these substances. Ethyl acetate extracts which, aside from phenolic acids, also contain flavonoids were analysed by Ultra Performance Liquid Chromatography-Quadrupole/Time of flight-mass spectrometry (UPLC-Q/TOF-MS). First, the mass spectra of 37 phenolic acids and flavonoids described in the literature were recorded. Consequently, sunflower honeys, lime honeys, clover honeys, rape honeys, and honeydew honeys were analysed in regard to these substances. By employing the ChromaLynx™ software, 34 of the 37 substances were identified quickly and clearly. By combining the retention time and the accurate molecular mass, it was even possible to identify several compounds which cannot be detected by diode array detection.
To explore alternative strategies to synthetic insecticides for control of Aethina tumida, the small hive beetle (SHB), treatments already established against two other honeybee pests, Varroa destructor and Galleria mellonella, were investigated. In the laboratory, eggs, larvae, and adults of SHB were treated with thymol (10, 20, and 50mg) or with
organic acids: 85% formic acid (0.125, 0.25, 0.5, 0.75, 1.0, and 2.0mL), 15% lactic acid (0.5, 1.0, 1.5, and 2.0mL), oxalic
acid (dihydrate crystals 35g/L; 0.25, 0.5, 0.75, 1.0, and 2.0mL), and 65% acetic acid (0.5, 1.0, 1.5, and 2.0mL). Some
of the chosen concentrations of formic and oxalic acid resulted in high mortalities of all SHB life stages. Therefore, they
were further evaluated in the field utilising standard methods for control of V. destructor in Europe. After exposure to evaporating formic acid (85%, Nassenheider®) and oxalic acid (2g dehydrate crystals, Varrox®),
mortality in all SHB tested stages did not increase significantly. The same was true for trials with 85% (adults) or 60% (eggs
and larvae) formic acid, evaporating from sponge tissues in diagnostic trays. In fact, some SHBs used the diagnostic trays
to hide or oviposit. Despite treating extracted honey combs with 65% acetic acid, SHBs still reproduced on the combs’ pollen
cells. In conclusion, none of the tested methods can be recommended to control SHBs.
–formic acid–lactic acid–oxalic acid–pest management–small hive beetle
Pollen is the natural source of protein for bees and it is commonly assumed that a high protein content in pollen is beneficial. Investigation of the optimal nutrient ratio for honeybees was prompted by our earlier study showing surprisingly high mortality in caged honeybees fed with the protein-rich pollen of Aloe greatheadii var davyana, although field bees experience optimal growth when feeding on this pollen. We tested the effect of different protein sources and different protein: carbohydrate (P:C) ratios on the survival and ovarian activation of caged bees. Bees fed casein showed consistently higher survival than those fed royal jelly or aloe pollen, regardless of P:C ratios. They survived longer on lower P:C ratios and longest on a pure carbohydrate diet. The greatest ovarian activation was recorded for bees fed royal jelly in a 1:3 P:C ratio, showing the superior quality of royal jelly for supporting development.
Unequal relatedness among workers in polyandrous honey bee colonies provides the potential for reproductive conflict during
emergency queen rearing. Adult workers can increase their inclusive fitness by selectively rearing their full-sisters as queens.
We investigated the paternity of emergency queens in two colonies of Apis florea using five microsatellite loci. In colony 1 there was no significant difference between the proportions of queens and workers
in each patriline (P = 0.48). In contrast, the relative frequency of patrilines in colony 2 differed significantly between queens and workers
(P = 0.03). More than a quarter of the queens reared in this colony were of a single patriline, suggesting that larvae were
selected for rearing as queens non-randomly.
–nepotism–emergency queen rearing–DNA microsatellites
The aim of this study was to evaluate the effect of thymol and resveratrol administered in two different formulation modes (candy and syrup) on the development of Nosema ceranae and on the longevity of honey bees. Emerging bees from a nosema-free apiary were individually infected with 1 μL of sucrose syrup containing 18000 spores of N. ceranae, placed in cages, and kept in an incubator at 33 °C and 65% RH. The experimental groups were fed candy or syrup prepared with thymol (100 ppm) or resveratrol (10 ppm). Infection levels were monitored over a 25 day period by removal and dissection of two live bees per cage. On day 25, post-infection bees fed with thymol syrup had significantly lower levels of infection (60 ± 9 million spores/bee) compared to control bees (138 ± 7 million spores/bee). Bees fed with thymol or resveratrol syrup lived significantly longer (23 and 25 days, respectively) than bees fed with control syrup (20 days). Thymol treated syrup appears to be promising in the control of nosema infection.
The small hive beetle (SHB, Aethina tumida) is a parasite and scavenger of honeybee colonies. Here, we conducted laboratory experiments to investigate the potential of SHB as a vector of honeybee viruses. Using RT-PCR methods, Deformed Wing Virus (DWV) was detected in adult SHBs that: (1) were fed with dead workers with deformed wings, (2) were fed with DWV-positive brood, and (3) were associated with DWV-contaminated wax. SHB became significantly more often infected through feeding on virus infected workers, brood and the virus contaminated wax compared to pollen and the controls, where no infections were found. DWV was also detected in adult SHB after trophallaxis with infected workers. Further, among SHBs identified as DWV-positive, 40% of beetles carried negative stranded RNA of DWV, indicating virus replication. Our results suggest that SHB can be infected with honeybee viruses via food-borne transmission and have the potential of being a biological vector of honeybee viruses.
The small hive beetle (SHB) is a parasite and scavenger of honey bee colonies. It has recently become an invasive species creating the need for an efficient and reliable detection method. We present a method to screen hive debris for the presence of SHB using real-time PCR in conjunction with an automated DNA extraction protocol. The method was able to detect DNA from SHB eggs, larvae and adult specimens collected from Africa, Australia and North America. The method was used to successfully detect SHB DNA extracted from spiked and naturally infested debris. An Apis mellifera 18S rRNA real-time PCR assay was used as an internal positive control (IPC). The IPC showed that the method was reliable for detection as extraction efficiency was consistent between hive debris samples. If the SHB were to establish at new locations, the availability of such a method would be a valuable support tool to enable species identification and rapid screening of hive debris for delimiting surveys.
Plant population size has been shown to affect insect visitation and reproductive success. Small populations are at risk because
individuals are more likely to be affected by stochastic processes and inbreeding depression (Allee effect). Additionally,
several studies have found that plants in small populations also experience lower pollinator visitation rates, which may further
decrease reproduction. In this study, seed set, pollinator visitation and pollen limitation of Thymus capitatus (L.) was assessed in 32 patches in eight populations of various sizes on the island of Lesvos, Greece. All populations except
one were significantly pollen-limited. We found that although free-pollinated flowers produced more seeds in larger populations
this was not due to higher pollinator visitation rates as flowers which received pollen supplements also produced more seeds
in larger populations. We hypothesize that the higher seed set is due to a generally greater genetic variability or better
habitat quality. We show that honeybee visitation alone significantly decreases pollen limitation.
–Lesvos–population size–patch size–pollen limitation
Body size is related to fitness in many insects. In solitary bees offspring body size is largely determined by maternal provisions and microclimate. We studied the effect of quantity and quality of provisions and rearing temperatures (20, 25 and 30 °C) on body size in the Red Mason bee, Osmia bicornis. Cocoon weight increased with provision weight and decreased with increasing temperature. High temperature (30 °C) led to high mortality of larvae and smaller body size, partly due to incomplete consumption of the provisions. Diversity of pollen in the provisions was low, and most provisions primarily consisted of mainly oak and maple pollen. Pollen diversity did not affect cocoon weight and males provided with pure oak or pure maple pollen showed similar adult size. Our results suggest that the quantity of provisions and temperature, but not pollen quality influence the development of O. bicornis progeny and might affect population dynamics of this abundant European pollinator.
Eggs of the honeybee Apis mellifera capensis from South Africa were screened for Wolbachia using degenerate primers designed to amplify a segment of the wsp A gene sequences. This strategy resulted in the identification of two new strains (wCap-B2, and -A1) in addition to the one (wCap-B1) characterized earlier from A. m. capensis and A. m. scutellata. Strain-specific primers were designed and used to assay eggs from both A. m. capensis and A. m. scutellata. The wCap-B1 sequence was amplified consistently from both A. m. capensis and A. m. scutellata, but the wCap-B2 and -A1 sequences were amplified sporadically only from A. m. capensis. This indicates that the wCap-B1 strain could be present at a higher titer or that wCap-B2 and -A1 are present only in some individuals in the wider A. m. capensis population. The detection of these new Wolbachia strains suggests that additional investigations are required to determine the role of Wolbachia in the biology of A. m. capensis workers.
We artificially inseminated queens of Apis mellifera scutellata and A. m. capensis with equal numbers of drones of both subspecies to determine the effects of sperm genotype on rates of sperm utilization.
Contrary to a previous study we did not find a consistent overrepresentation of workers sired by A. m. scutellata males in the first four months after insemination. Interestingly, our study does suggest that there is a significant interaction
between drone and queen genotype in both subspecies, with queens of each subspecies producing more workers sired by drones
of the same subspecies.
Apis mellifera scutellata
Apis mellifera capensis
–sperm competition–Africanization–hybrid zone
Honeybees are native to Africa and Europe but have been spread worldwide as the basis for an apicultural industry. To date, large and diverse wild populations only remain in Africa. On this continent the beekeeping industry is relatively undeveloped and relies on trapping swarms from wild populations to constitute the managed stocks. Bee breeding is seldom practiced. The situation is therefore different from that of Europe or North America where wild or feral honeybees have almost disappeared and this distinction is important when assessing the conservation status of African honeybees. While African honeybees appear to be more resistant to major diseases, the history of honeybee populations worldwide suggests that their conservation is a necessity. After analyzing the threats to which honeybees are exposed in Africa, we argue that preventive conservation measures are required to maintain the present favorable situation and avoid the declines in populations experienced elsewhere.
Nectar foraging by species of two stingless bees was studied in an African tropical rain forest. Both species Hypotrigona gribodoi (2-3 mm) and Meliponula ferruginea (6 mm) collected nectar with a wide range of sugar concentration (H. gribodoi: 14.2-67.4%; M. ferruginea: 9.1-63.4%). H. gribodoi collected nectar of higher sugar concentration than M. ferruginea. Factors that influenced sugar concentration of collected nectar included botanic origin of the nectar, bee species, bee colonies, month of year, time of day and the local environment. Sugar concentration increased gradually from 0700 h to a peak at 1300 h and declined thereafter. H. gribodoi collected nectar from more diverse plant species than M. ferruginea. Sugar concentration for both bee species was higher during the dry season than the rainy season. Although the above factors may explain part of the variation in the sugar concentration of nectar, additional explanations lie in the behavioural differences among the bee species.
Africanized honey bees (Apis mellifera; AHB) are predominant in tropical Mexico. A selection program using local AHBs colonies is a good alternative to provide beekeepers with good quality queens. We evaluated the application of field and laboratory tests to predict the production of honey in AHBs from Yucatan, Mexico. Five variables were measured in worker bees in the laboratory: longevity, amount of syrup removed, hoarding, weight of pupae and corbicular area. Three additional variables were measured in the field: rate of foraging activity, volume of honey sac contents and colony weight gain per week. Our results showed that weekly colony weight gain had the highest correlation with honey production in AHBs. Only the corbicular area and worker longevity were not correlated with honey production (r = 0.256 and r = 0.074, respectively P > 0.05). Thus, short term colony weight gain can be recommended as a good estimate of honey production in AHBs and lab tests can be included as selection aids.
As with most solitary bees, larvae of the alfalfa leaf-cutting bee, Megachile rotundata Fab., eat a diet blended from pollen and nectar of unknown proportions. In this study, we developed protocols to isolate
and quantify sugars from larval provision masses. The method removed free amino acids that leach from pollen and confound
chromatography, but without autohydrolyzing sucrose. Pollen sugars were a negligible fraction of provision mass sugars. Glucose
and fructose constituted about half of the provision fresh weight. Sucrose in alfalfa pollen and nectar is absent from the
provision, presumably enzymatically hydrolyzed to glucose and fructose in the provision. Provision masses are composed of
two to three times more floral equivalents in pollen than nectar. Female M. rotundata, and other solitary bees with pasty provisions, gather proportionally more pollen than nectar compared with the resource
needs of colonies of social honeybees and bumblebees.
Although the alien Impatiens glandulifera successfully invades riparian habitats and is visited by native insects, knowledge of its impact on native bees is limited. We assessed pollinator abundance in field sites where I. glandulifera was absent, present or had been experimentally removed. We measured insect visitation to flowers of potted native plants and to I. glandulifera. Bombus spp. comprised the highest proportion of visitors in invaded sites, whereas solitary bees made up the highest proportion in sites where I. glandulifera was removed. More bees, especially medium- and long-tongued Bombus spp. (B. pascuorum and B. hortorum), foraged on I. glandulifera than the native plant species (possibly because the alien was more abundant). We detected no impact of invasion on standardised pollinator abundance, B. pascuorum abundance, nor functional insect diversity, which may be due to variable climatic conditions. We suggest that future studies focus on impacts on rare or specialised pollinator taxa.
Beeswax is composed of fatty acids, odd numbered n-alkanes and wax esters. Focusing on the most stable components of beeswax, namely the n-alkanes, we have found by gas chromatography and gas chromatography-mass spectrometry analyses of combs from twelve colonies from Israel and Jordan that as beeswax ages and darkens its n-alkane composition changes. The amount of even numbered n-alkanes (C22– C32) is significantly higher in darker colored beeswax as compared to light colored beeswax. We attribute this in part to the accumulation of cuticular residues found in the darker colored comb cells. Cuticular residues are known to contain C23–C32 odd and even numbered n-alkanes.
Multifemale nests of Euglossa carolina were studied to investigate task allocation during nest reactivations according to both the females’ size and order of emergence.
The study was carried out at the campus of the University of São Paulo, Ribeirão Preto, Brazil, from January, 1990 to March,
1992. The activities of the females were recorded during the reactivation processes in eight nests maintained in observation
boxes. The size of each female was determined by measuring the forewing length and the maximum width of the head. Nest reactivations
were performed by one or more females in the presence or absence of a female that had participated in a previous reactivation
process. Usually, the first emerging females remained in the nests and established associations in which the oldest became
dominant. All nestmates had mated, and developed ovaries and did not differ in size. Task allocation was recognized by behavioral
characteristics, namely, agonism and oophagy in cells oviposited by other females.
–reproductive skew–oophagy–social structure–task allocation
Honeybees (Apis mellifera) and their resource-rich nests are hosts to a wide range of saprophytic fungi, including species that produce mycotoxins.
The toxicity of aflatoxin B1 (AB1) and ochratoxin A (OTA), products of Aspergillus species often found in honeybee hives, was evaluated and LC50 values for both toxins were calculated. Workers can tolerate a wide range of concentrations of both OTA and AB1. At low concentrations,
AB1 (1 μg/g and 2.5 μg/g diet) and OTA (1 μg/g) did not have any apparent toxic effects on bees. Enhancement of the toxicity
of AB1 by piperonyl butoxide (PBO), a known inhibitor of cytochrome P450 monooxygenases, indicates a role for P450s in AB1
detoxification in honeybees. Extracts of propolis, a complex mixture of plant-derived chemicals, including many flavonoids
and other phenolic compounds, similarly ameliorated aflatoxin toxicity and delayed the onset of mortality. Collectively, these
results suggest that tolerance of AB1 by honeybees may be due to P450-mediated metabolic detoxification. Propolis may serve
a hitherto unrecognized role in honey bee health by enhancing the activity of P450 enzymes involved in mycotoxin detoxification.
Keywordshoneybee–aflatoxin B1–ochratoxin A–cytochrome P450 monooxygenases–piperonyl butoxide–propolis
Historic data in the form of pinned specimens in entomological collections offer the potential to determine trends in genetic diversity of bumble bees (Bombus). We screened eight microsatellite loci in pinned bumble bee specimens from the U. S. National Pollinating Insects Collection. We tested three species (Bombus appositus, Bombus huntii and Bombus occidentalis) representing three subgenera of bumble bees (Subterraneobombus, Pyrobombus and Bombus sensu stricto) respectively. Bombus occidentalis is a species of particular concern for conservation biologists. Single mid-legs of ninety-six individuals from each species were assayed to determine microsatellite amplification success rates of historic material in a museum collection. Microsatellite alleles amplified in specimens up to 101 years old, but the rate of amplification success was significantly lower in material over 60 years of age. Loci with shorter allele sizes amplified more frequently than relatively longer alleles in samples from all age classes.We correlate the age of specimens to the age at which loci fail to amplify and discuss potential impacts of using certain markers for population genetic studies of museum specimens.
We investigate of two aspects of pollen diet of Andrena bees: the evolution of diet breadth within nearctic representatives of the genus, which includes both polylectic and oligolectic species; and host choice within an oligolectic clade of Andrena. We also evaluate phenology. Traits were mapped onto a molecular phylogeny to identify the ancestral character states. Overall, oligolecty appears to be the basal state within Andrena, and broader diets have evolved a number of times, suggesting that specialization is not a "dead end". Within the oligolectic clade studied, host shifts occur predominantly between members of the same plant tribe, indicating a phylogenetic constraint to host-usage; however, shifts to other tribes are not uncommon, and may lead to adaptive radiation. Additionally, some lineages retain the ability to use pollen from an ancestral host-plant tribe. Finally, we find a correlation between using host plants in the family Asteraceae and fall emergence.
The geographical distributions of the dwarf honeybees, Apis andreniformis and Apis florea, are defined and mapped. The analysis is based primarily on data in the literature for both species and that on the relevant
Quaternary palaeoclimatic data. The dwarf honeybee, A. andreniformis, extends from the eastern foothills of the Himalayas eastward to Indochina, Sundaland and the Philippines. A. florea extends from eastern Oman into southern Iran, eastwards along the foothills of the Himalayas and abruptly stops in southern
Thailand. Because they are only partially sympatric, the palaeoclimatic circumstances under which they may have speciated
allopatrically are considered. A common and widespread pre-florea/andreniformis split could have occurred in the early Pleistocene followed by the Pre-Pastonian glacial (800–1,300ka) which could well
have provided a substantial barrier to gene flow for the then evolving proto-populations of A. andreniformis and A. florea.
For many organisms, choosing an appropriate nest site is a critical component of reproductive fitness. Here we examine nest
site selection in the solitary, resource defense polygynous bee, Anthidium manicatum. Using a wood-framed screen enclosure outfitted with food sources, nesting materials, and bamboo trap nests, we show that
female bees prefer to initiate nests in sites located high above the ground. We also show that nest sites located at higher
levels are less likely to contain spiderwebs, suggesting an adaptive explanation for nest site height preferences. We report
size differences between this study’s source populations in Boston, Massachusetts and Brooklyn, New York; male bees collected
in Boston have smaller mean head widths than males collected in Brooklyn. Finally, we argue that methods for studying captive
populations of A. manicatum hold great promise for research into sexual selection, alternative phenotypes, recognition systems, and the evolution of
KeywordsMegachilidae–introduced species–solitary bee–enclosure methods
Western honey bees (Apis mellifera) are under threat from a number of emerging pathogens, including the microsporidian Nosema ceranae historically of Asian honey bees (Apis cerana). Because of its recent detection, very little is known about the biology, pathology, and control of N. ceranae in western honey bees. Here we investigated effects of the antibiotic Fumagilin-B®, which is commonly used to control the
historical Nosema parasite of western honey bees Nosema apis, on N. ceranae and effects of N. ceranae on colony strength (i.e., number of bees and amount of capped and uncapped brood, honey, and pollen) and colony mortality.
Similar to our previous study, fall Fumagilin-B® treatment lowered, albeit weakly, N. ceranae intensity the following spring. However, N. ceranae was not associated with variation in colony strength measures or with higher colony winter mortality.
The aims of this study were to identify the bacterial genera and species present in semen of Apis mellifera and to evaluate the sensitivity of those bacteria to different antibiotics. Mesophilic aerobic and microaerophilic bacteria
were characterized in semen samples from different hives, and the number of total viable bacteria per milliliter of semen
was determined. Twenty-nine isolates were obtained, and 14 different genera were identified, some of them being monomicrobians
and others polymicrobians. Colony-forming units (CFU) were variable from no bacterial development up to 4 × 105CFU/mL. The most frequent genera were Bacillus and Staphylococcus. All the studied isolates were sensitive to gentamicin and amikacin. Spermatozoa viability in sperm samples diluted in buffer
with antibiotic was similar to that of pure semen.
–semen–bacterial content–antibiotics susceptibility
This study investigated the reproductive biology of the meloid beetle Meloetyphlus fuscatus Waterhouse, a cleptoparasite of Eulaema nigrita nests. New E. nigrita nests had rates of cell parasitism by meloids ranging from 3.7% to 15.8%, while in re-used nests the rate of cell parasitism
ranged from 1.4% to 18.7%. The adult parasites were never observed trying to leave the host nests. Both sexes mated more than
once. Females had a high fecundity (more than 8,000 eggs), and in most cases, deposited their eggs into the empty, old cells
of the host. The triungulins (the first larval instars) hatched from eggs 18–20days after oviposition and dispersed from
the host nest by attaching themselves to males as they emerged. The triungulins most likely transfer to female bees during
mating and are transported to the nests of their hosts. Within an attacked cell, the triungulin consumes the bee egg and completes
its development by consuming the larval food stored in the cell.
Pollen sources used by Centris tarsata bees were identified in an area of “caatinga” vegetation (Canudos Biological Station) in NE Bahia, NE Brazil, by analyzing the pollen residues encountered in the nests. The analysis of the pollen residues was performed by pulverizing the sediments used to construct the cells, followed by the application of the acetolysis method. Thirty-one pollen types were identified belonging to 13 botanical families (in associations of from 4 to 15 distinct pollen types per nest), indicating which plants were used by the bees to feed their offspring. The plant families most represented were Leguminosae and Malpighiaceae, while the pollen types most frequently found were Chamaecrista ramosa (46.5%), Senna rizzinii (19.7%), and Solanum paniculatum (19.6%). The identification of the pollen types and information about the resources offered by the plants indicated that many species were visited as nectar sources rather than as pollen or oil sources by C. tarsata.