Search

Certain populations of feral or wild European Honey Bees (EHB), Apis mellifera, have developed a tolerance of or persistence against the parasitic mite Varroa destructor in the USA. Although the grooming or mite-biting behavior is a trait bees use to defend against parasitic Varroa mites, little information is available concerning the grooming or mite-biting behavior of feral EHBs. Accordingly, we observed damaged mites of feral bees in Ohio (Apis mellifera ligustica) and commercial bees in four field seasons, 2020 to 2023, as well as feral bees in Kentucky (A. mellifera mellifera) in 2023, for a total of 7494 mites. When the mite-biting behavior was compared among these three populations, feral bees of Ohio (A. m. ligustica) and Kentucky (A. m. mellifera) displayed a significantly higher percentage (22% and 27% more) than the commercial bees. To investigate the mechanism of the mite-biting behavior, we examined bee mandibles. Mandibles are the primary mouthparts and tools used to remove or amputate the Varroa mites. Gentle Africanized honey bees (gAHB, A. mellifera scutellata-hybrid) in Puerto Rican exhibit mite resistance through microevolution on the island. Asian honey bees (A. cerana) are the original natural host of V. destructor. However, little has been reported on the morphometric analysis of mandibles between the two species A. cerana and A. mellifera and between the subspecies A. m. scutellata-hybrid and A. m. ligustica. Utilizing X-ray micro-computed tomography (microCT), we then examined the three-dimensional morphology of mandibles in (1) A. cerana, (2) gAHB A. m. scutellata-hybrid, (3) Ohio feral A. m. ligustica, and (4) package or commercial colonies A. m. ligustica. Our findings revealed distinctive three-dimensional shapes of mandibles, indicating substantial variations among these populations. These variations suggest that mandible morphology has an integral role in the bee’s defensive mechanisms against parasitic mites. We also developed the first smartphone application to quantify the mite damage by applying artificial intelligence to image analysis. This research contributes valuable insights into the prospective selection and breeding of honey bees with enhanced mite resistance, thus promoting the sustainability of apiculture. [ABSTRACT FROM AUTHOR]

The East African lowland honey bee (Apis mellifera scutellata) is reported as an aggressive subspecies of the Western honey bee, but few studies have investigated the impact of its aggressiveness on other insect pollinators. Observations of flower visitors to Vachellia (Acacia) etbaica and interactions between honey bees and other insects were conducted in 2022 in Mpala, Kenya. A total of 873 individual flower visitors were recorded, the most frequent being Hymenoptera, followed by Diptera and Lepidoptera. Honey bees dominated floral resources in the morning and late afternoon. When honey bees encountered other types of insects, they displaced the latter from flowers 100% of the time. This has never been observed in other Western honey bee subspecies, and we recommend further research on these taxa. [ABSTRACT FROM AUTHOR]

ABSTRACT A case of a donkey attacked by Africanized honeybee is reported here with clinical signs of agitation, dehydration, congestion of the ocular mucous membranes, tongue edema, tachycardia and inspiratory dyspnea, and progression to death. At necropsy, diffuse, severe subcutaneous edema at face and cervical regions and severe diffuse pulmonary hyperemia with abundant edema without parenchymal collapse were observed. Microscopically, marked, diffuse deep dermis and panniculus carnosus edema and marked diffuse alveolar edema, with moderate population of eosinophils predominantly around larger caliber vessels were noted. The final diagnosis of anaphylactic shock was supported by history, clinical signs, and anatomic pathology findings. This is the first report of a honeybee attack with pulmonary eosinophilic infiltration in a mammal.

Honey bees play a critical role in ecosystem health, biodiversity maintenance, and crop yield. Antimicrobials, such as tetracyclines, are used widely in agriculture, medicine, and in bee keeping, and bees can be directly or indirectly exposed to tetracycline residues in the environment. In European honey bees, tetracycline exposure has been linked with shifts in the gut microbiota that negatively impact bee health. However, the effects of antimicrobials on Africanized honey bee gut microbiota have not been examined. The aim of this study was to investigate the effects of tetracycline exposure on the gut microbial community of Africanized honey bees (Apis mellifera scutellata x spp.), which are important pollinators in South, Central, and North America. Bees (n = 1,000) were collected from hives in Areia-PB, Northeastern Brazil, placed into plastic chambers and kept under controlled temperature and humidity conditions. The control group (CON) was fed daily with syrup (10 g) consisting of a 1:1 solution of demerara sugar and water, plus a solid protein diet (10 g) composed of 60% soy extract and 40% sugar syrup. The tetracycline group (TET) was fed identically but with the addition of tetracycline hydrochloride (450 μg/g) to the sugar syrup. Bees were sampled from each group before (day 0), and after tetracycline exposure (days 3, 6, and 9). Abdominal contents dissected out of each bee underwent DNA extraction and 16S rRNA sequencing (V3-V4) on an Illumina MiSeq. Sequences were filtered and processed through QIIME2 and DADA2. Microbial community composition and diversity and differentially abundant taxa were evaluated by treatment and time. Bee gut microbial composition (Jaccard) and diversity (Shannon) differed significantly and increasingly over time and between CON and TET groups. Tetracycline exposure was associated with decreased relative abundances of Bombella and Fructobacillus, along with decreases in key core microbiota such as Snodgrassella, Gilliamella, Rhizobiaceae, and Apibacter. These microbes are critical for nutrient metabolism and pathogen defense, and it is possible that decreased abundances of these microbes could negatively affect bee health. Considering the global ecological and economic importance of honey bees as pollinators, it is critical to understand the effects of agrochemicals including antimicrobials on honey bees.

Bees are insects of the order Hymenoptera and are involved in human accidents. In Brazil, bees that cause accidents are crosses derived from Europeans with African bees and are known for their aggressive behavior. Despite being considered an important public health concern, epidemiological studies at the national level are scarce. The objective of this study was to verify the epidemiological profile of bee accidents in humans in Brazil, using data from 2009 to 2019 of the Brazilian Ministry of Health. It was found that bee accidents increased by 207.61% from the first to the last year of the present study. The incidence varied according to the geographical region; the southern region had more bee accidents, but the Northern region had more deaths caused by bee accidents. Besides, climatic conditions were associated with susceptibility to bee stings; the incidence was higher during spring and summer. Age was also associated with fatality rate, with the elderly being the group with the highest fatality rate. Our results demonstrate that accidents caused by bees involve factors related to patients, the environment, and the behavior of bees. It is important to know the epidemiological aspects to help prevent apidic accidents. • Bee stings in Brazil increased 207,61% in the last ten years, but fatality rate has decreased 35%. • Centers of Toxicologic Information distributed in all country, may have contributed to decreased fatality rate. • The increase in bee stings observed during spring and summer may be associated with the reproductive period of bees. • Elderly patients require more attention since there is a higher fatality rate among them. [ABSTRACT FROM AUTHOR]

A real-time qPCR assay was designed to detect African-derived subspecies of western honey bees (Apis mellifera L.). The probes targeted the same region of the mitochondrial cytochrome b gene used in previous restriction enzyme assays. Using samples from 16 A. mellifera subspecies representing four lineages, we evaluated the efficacy of this assay to identify African- (or A-lineage) and non-A-lineage honey bees. The qPCR assay successfully differentiated A-lineage honey bees, including A. m. scutellata and A. m. capensis, from M-, C-, and O-lineage A. mellifera subspecies. In conclusion, the assay we developed is useful for rapid detection of A-lineage honey bees in areas where they are introduced, although it cannot be used to identify the specific A. mellifera subspecies within the A-lineage. [ABSTRACT FROM AUTHOR]

Propolis is a hive product composed of biologically active plant resins, and has been shown to enhance individual honey bee (Apis mellifera L.) health. Propolis has also been demonstrated to mitigate, in part, the negative effects caused by the ecto-parasitic mite Varroa destructor and its associated viruses on the health of managed European honey bee colonies. However, its effect on the health status of African honey bees remains largely unknown. Here, we found that the African savannah honey bees, A. m. scutellata in Kenya, deposited approximately two and half-fold more propolis in their colonies during periods of increased than reduced worker brood rearing. This finding suggested that A. m. scutellata may use high quantities of propolis prophylactically to protect their young brood; yet, we observed no significant correlation between the quantity of propolis and the amount of worker brood or mite-infestation level on adult workers. Furthermore, whereas propolis volatiles or propolis placed in direct contact with the mites had no effect on mite survival under laboratory conditions, the ethanolic extract of propolis significantly reduced mite survival when compared with untreated control. These results suggest the presence of mite deterrent compounds in the ethanolic extract of the African honey bee propolis. [ABSTRACT FROM AUTHOR]

Abstract Backgrounds Apis mellifera scutellata and A.m. capensis (the Cape honey bee) are western honey bee subspecies indigenous to the Republic of South Africa (RSA). Both bees are important for biological and economic reasons. First, A.m. scutellata is the invasive “African honey bee” of the Americas and exhibits a number of traits that beekeepers consider undesirable. They swarm excessively, are prone to absconding (vacating the nest entirely), usurp other honey bee colonies, and exhibit heightened defensiveness. Second, Cape honey bees are socially parasitic bees; the workers can reproduce thelytokously. Both bees are indistinguishable visually. Therefore, we employed Genotyping-by-Sequencing (GBS), wing geometry and standard morphometric approaches to assess the genetic diversity and population structure of these bees to search for diagnostic markers that can be employed to distinguish between the two subspecies. Results Apis mellifera scutellata possessed the highest mean number of polymorphic SNPs (among 2449 informative SNPs) with minor allele frequencies > 0.05 (Np = 88%). The RSA honey bees generated a high level of expected heterozygosity (H exp = 0.24). The mean genetic differentiation (F ST; 6.5%) among the RSA honey bees revealed that approximately 93% of the genetic variation was accounted for within individuals of these subspecies. Two genetically distinct clusters (K = 2) corresponding to both subspecies were detected by Model-based Bayesian clustering and supported by Principal Coordinates Analysis (PCoA) inferences. Selected highly divergent loci (n = 83) further reinforced a distinctive clustering of two subspecies across geographical origins, accounting for approximately 83% of the total variation in the PCoA plot. The significant correlation of allele frequencies at divergent loci with environmental variables suggested that these populations are adapted to local conditions. Only 17 of 48 wing geometry and standard morphometric parameters were useful for clustering A.m. capensis, A.m. scutellata, and hybrid individuals. Conclusions We produced a minimal set of 83 SNP loci and 17 wing geometry and standard morphometric parameters useful for identifying the two RSA honey bee subspecies by genotype and phenotype. We found that genes involved in neurology/behavior and development/growth are the most prominent heritable traits evolved in the functional evolution of honey bee populations in RSA. These findings provide a starting point for understanding the functional basis of morphological differentiations and ecological adaptations of the two honey bee subspecies in RSA.

There are two endemic subspecies of western honey bees (Apis mellifera L.) in the Republic of South Africa (RSA), A.m. capensis and A.m. scutellata. They have traditionally been identified using morphometric characteristics, but geometric morphometric data from honey bee wings are easier to collect, possibly making them a useful alternative for identifying these subspecies. We compared the accuracy of both morphometric and geometric morphometric methods using linear discriminant and classification and regression tree analyses. We found that using geometric wing shape data from both forewings and hindwings resulted in a lower classification accuracy (73.7%) than did using models derived from the full set of standard morphometric data (97% accurate) in cross-validation. Tergite color and average ovariole number were the most important features for discriminating between the two subspecies. Finally, we used Kreiger interpolation to construct maps illustrating probable distributions of A.m. capensis and A.m. scutellata in the RSA. [ABSTRACT FROM AUTHOR]

Backgrounds: Apis mellifera scutellata and A.m. capensis (the Cape honey bee) are western honey bee subspecies indigenous to the Republic of South Africa (RSA). Both bees are important for biological and economic reasons. First, A.m. scutellata is the invasive “African honey bee” of the Americas and exhibits a number of traits that beekeepers consider undesirable. They swarm excessively, are prone to absconding (vacating the nest entirely), usurp other honey bee colonies, and exhibit heightened defensiveness. Second, Cape honey bees are socially parasitic bees; the workers can reproduce thelytokously. Both bees are indistinguishable visually. Therefore, we employed Genotyping-by-Sequencing (GBS), wing geometry and standard morphometric approaches to assess the genetic diversity and population structure of these bees to search for diagnostic markers that can be employed to distinguish between the two subspecies. Results: Apis mellifera scutellata possessed the highest mean number of polymorphic SNPs (among 2449 informative SNPs) with minor allele frequencies > 0.05 (Np = 88%). The RSA honey bees generated a high level of expected heterozygosity (Hexp = 0.24). The mean genetic differentiation (FST; 6.5%) among the RSA honey bees revealed that approximately 93% of the genetic variation was accounted for within individuals of these subspecies. Two genetically distinct clusters (K = 2) corresponding to both subspecies were detected by Model-based Bayesian clustering and supported by Principal Coordinates Analysis (PCoA) inferences. Selected highly divergent loci (n = 83) further reinforced a distinctive clustering of two subspecies across geographical origins, accounting for approximately 83% of the total variation in the PCoA plot. The significant correlation of allele frequencies at divergent loci with environmental variables suggested that these populations are adapted to local conditions. Only 17 of 48 wing geometry and standard morphometric parameters were useful for clustering A.m. capensis, A.m. scutellata, and hybrid individuals. Conclusions: We produced a minimal set of 83 SNP loci and 17 wing geometry and standard morphometric parameters useful for identifying the two RSA honey bee subspecies by genotype and phenotype. We found that genes involved in neurology/behavior and development/growth are the most prominent heritable traits evolved in the functional evolution of honey bee populations in RSA. These findings provide a starting point for understanding the functional basis of morphological differentiations and ecological adaptations of the two honey bee subspecies in RSA. [ABSTRACT FROM AUTHOR]

Varroa-specific hygienic behavior is a hereditary trait of honey bee (Apis mellifera), which supports resistance to Varroa destructor. This study investigated the response of Apis mellifera scutellata to Varroa-infested worker brood cells in Kenya, East Africa. Uncapping, removal of the brood, and disappearance of the introduced mite were recorded in a total of 690 cells into which live mites were introduced. We recorded a high proportion of untouched cells in controls (median, 80%) compared to manipulated cells in which mites had been introduced (median, 12.5%) with a significant difference (GLMM, p < 0.001). Mites were removed and cells were recapped in about 26% of the artificially infested brood cells. When ten, eight, and five mites were singly introduced in closely neighboring brood cells, hygienic bees were more responsive in the high mite density regime of eight and ten mites, an indication of a possibility that chemicals play a role in identification of Varroa-infested brood cells. [ABSTRACT FROM AUTHOR]

For two decades, neonicotinoid insecticides have been extensively used worldwide. Targeting neuronal receptors, they have deleterious effects on the behaviour and physiology of many insects. Bees are exposed to these insecticides in pollen and nectar while providing pollination services to agricultural crops, and neonicotinoids have been shown to impair navigation and decrease their foraging activity. We have previously reported the effect of dietary thiamethoxam on sucrose responsiveness of young worker bees. Here, we exposed caged foragers to sublethal acute doses of clothianidin, imidacloprid, and thiamethoxam, then tested them individually for sucrose responsiveness using standard methods. In addition, we tested the response to a range of sucrose solutions laced with neonicotinoids on bees previously unexposed to neonicotinoids. This paradigm mimics the situation where foragers would first encounter poisoned nectars varying in sugar concentration. Bees were exposed to the insecticides in the feeding solution for 24 h before testing, or in the test solutions, or both. The three compounds had a detrimental effect on responses to mid-to-high sucrose concentrations under all experimental conditions, and unexposed bees tested with laced sucrose displayed unexpected low responses to the higher sucrose concentrations tested. This attenuation of sucrose response is further evidence that neonicotinoids are multisensory disruptors, with potent actions against pollinators and other beneficial insects at first contact. [ABSTRACT FROM AUTHOR]

Honey bees ( Apis mellifera ) are generalist pollinators that forage for nectar and pollen of a very large variety of plant species, exposing them to a diverse range of secondary metabolites produced as chemical defences against herbivory. Honey bees can tolerate high levels of many of these toxic compounds, including the alkaloid nicotine, in their diet without incurring apparent fitness costs. Very little is known about the underlying detoxification processes mediating this tolerance. We examined the metabolic fate of nicotine in newly emerged worker bees using radiolabeled nicotine and LC-MS/MS analysis to determine the kinetic distribution profile of nicotine as well as the absence or presence and identity of any nicotine-derived metabolites. Nicotine metabolism was extensive; virtually no unmetabolised nicotine were recovered from the rectum. The major metabolite found was 4-hydroxy-4-(3-pyridyl) butanoic acid, the end product of 2′C-oxidation of nicotine. It is the first time that 4-hydroxy-4-(3-pyridyl) butanoic acid has been identified in an insect as a catabolite of nicotine. Lower levels of cotinine, cotinine N-oxide, 3′hydroxy-cotinine, nicotine N-oxide and norcotinine were also detected. Our results demonstrated that formation of 4-hydroxy-4-(3-pyridyl) butanoic acid is quantitatively the most significant pathway of nicotine metabolism in honey bees and that the rapid excretion of unmetabolised nicotine does not contribute significantly to nicotine tolerance in honey bees. In nicotine-tolerant insects that do not rely on the rapid excretion of nicotine like the Lepidoptera, it is possible that the 2′C-oxidation of nicotine is the conserved metabolic pathway instead of the generally assumed 5′C-oxidation pathway. [ABSTRACT FROM AUTHOR]

The small hive beetle (SHB), Aethina tumida, a parasite of honey bees is endemic to Sub-Saharan Africa and has become a global invasive pest. Adequate surveillance methods based on trapping methods need testing and verification of their efficacy. We tested the efficacy of top frame supplied cardboard traps. The efficacy was extremely low (0.9%) and significantly less effective than bottom board placed traps. [ABSTRACT FROM AUTHOR]

Varroa destructor Anderson & Trueman ( Varroa) is a damaging pest of the Western honey bee, Apis mellifera, in North America, Europe, and Asia. However, Varroa infestations have not produced equivalent colony losses of African subspecies of honey bee throughout Africa and parts of the Americas. We surveyed the Varroa infestation rates (number of Varroa per 100 adult honey bees) in colonies of A. m. scutellata, A. m. capensis, and hybrids of the two subspecies throughout the Republic of South Africa in the fall of 2014. We found that A. m. scutellata colonies had significantly higher Varroa infestations than did A. m. capensis colonies. Furthermore, hybridized colonies of the two subspecies had Varroa infestations intermediate to those of A. m. scutellata and A. m. capensis. This is the first documentation of a clear difference in Varroa infestation rates of A. m. scutellata, A. m. capensis, and hybridized colonies in South Africa. Furthermore, our data confirm that Varroa populations in A. m. scutellata colonies are within the range of populations that are damaging to European honey bees. [ABSTRACT FROM AUTHOR]

Varroa destructor is considered the most damaging parasite affecting honeybees (Apis mellifera L.). However, some honeybee populations such as the savannah honeybee (Apis mellifera scutellata) can survive mite infestation without treatment. It is unclear if survival is due to resistance mechanisms decreasing parasite reproduction or to tolerance mechanisms decreasing the detrimental effects of mites on the host. This study investigates both aspects by quantifying the reproductive output of V. destructor and its physiological costs at the individual host level. Costs measured were not consistently lower when compared with susceptible honeybee populations, indicating a lack of tolerance. In contrast, reproduction of V. destructor mites was distinctly lower than in susceptible populations. There was higher proportion of infertile individuals and the reproductive success of fertile mites was lower than measured to date, even in surviving populations. Our results suggest that survival of savannah honeybees is based on resistance rather than tolerance to this parasite. We identified traits that may be useful for breeding programmes aimed at increasing the survival of susceptible populations. African honeybees may have benefited from a lack of human interference, allowing natural selection to shape a population of honeybees that is more resistant to Varroa mite infestation. [ABSTRACT FROM PUBLISHER]

Flowering plants typically use floral rewards to attract animal pollinators. Unlike nectar, pollen rewards are usually visible and may thus function as a signal that influences landing decisions by pollen-seeking insects. Here we artificially manipulate the presence of both pollen and staminal hairs (a putative false signal of pollen reward availability) in the hermaphroditic lily Bulbine abyssinica ( Xanthorrhoeaceae) to investigate their effects on bee visitation and fecundity, and also test for trade-offs between pollen production and seed production. Honeybees, the primary floral visitors, are probably not able to distinguish between colours of petals, staminal hairs and pollen of B. abyssinica, according to analysis of reflectance spectra in a bee vision model. Flowers with both pollen and hairs removed had the lowest levels of bee visitation, seed set and seed abortions. Flowers containing hairs had an ∼50% increase in visitation rate and seed set compared with emasculated flowers, while intact controls had the highest seed abortion rate. Ovule discounting in intact flowers is probably due to ovarian self-incompatibility (or strong early inbreeding depression) as ovules penetrated by tubes from self-pollen uniformly failed to develop into seeds. These results show that staminal hairs can enhance plant fecundity by increasing attraction of pollen-seeking insects to flowers without increasing the risk of ovule discounting through pollinator-mediated self-pollination. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 177, 481-490. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Field Ornithology is the property of Resilience Alliance and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The devastating effects of Varroa destructor Anderson & Trueman on European honeybee colonies ( Apis mellifera L.) have been well documented. Not only do these mites cause physical damage to parasitised individuals when they feed on them, they also transmit viruses and other pathogens, weaken colonies and can ultimately cause their death. Nevertheless, not all honeybee colonies are doomed once Varroa mites become established. Some populations, such as the savannah honeybee, A. m. scutellata, have become tolerant after the introduction of the parasite and are able to withstand the presence of these mites without the need for acaricides. In this study, we measured daily Varroa mite fall, Varroa infestation rates of adult honeybees and worker brood, and total Varroa population size in acaricide treated and untreated honeybee colonies. In addition, honeybee colony development was compared between these groups in order to measure the cost incurred by Varroa mites to their hosts. Daily Varroa mite fall decreased over the experimental period with different dynamics in treated and untreated colonies. Varroa infestation rates in treated adult honeybees and brood were lower than in untreated colonies, but not significantly so. Thus, indicating a minimal benefit of treatment thereby suggesting that A. m. scutellata have the ability to maintain mite populations at low levels. We obtained baseline data on Varroa population dynamics in a tolerant honeybee over the winter period. Varroa mites appeared to have a low impact on this honeybee population, given that colony development was similar in the treated and untreated colonies. [ABSTRACT FROM AUTHOR]

Over-consuming amino acids is associated with reduced survival in many species, including honeybees. The mechanisms responsible for this are unclear but one possibility is that excessive intake of amino acids increases oxidative damage. If this is the case, antioxidant supplementation may help reduce the survival costs of high amino acid intake. We tested this hypothesis in African honeybees ( Apis mellifera scutellata ) using the major antioxidant in green tea, epigallocatechin-3-gallate (EGCG). We first determined the dose-range of EGCG that improved survival of caged honeybees fed sucrose solution. We then provided bees with eight diets that differed in their ratio of essential amino acids (EAA) to carbohydrate (C) (0:1, 1:250, 1:100, 1:75, 1:50, 1:25, 1:10, 1:5 EAA:C) and also in their EGCG dose (0.0 or 0.4 mM). We found that bees fed sucrose only solution survived better than bees fed EAA diets. Despite this, bees preferred a diet that contained intermediate ratios of EAA:C (ca. 1:25), which may represent the high demands for nitrogen of developing nurse bees. EGCG supplementation improved honeybee survival but only at an intermediate dose (0.3–0.5 mM) and in bees fed low EAA diets (1:250, 1:100 EAA:C). That EGCG counteracted the lifespan reducing effects of eating low EAA diets suggests that oxidative damage may be involved in the association between EAAs and lifespan in honeybees. However, that EGCG had no effect on survival in bees fed high EAA diets suggests that there are other physiological costs of over-consuming EAAs in honeybees. [ABSTRACT FROM AUTHOR]

The effects of pesticides on honeybee larvae are less understood than for adult bees, even though larvae are chronically exposed to pesticide residues that accumulate in comb and food stores in the hive. We investigated how exposure to a plant alkaloid, nicotine, affects survival, growth and body composition of honeybee larvae. Larvae of Apis mellifera scutellata were reared in vitro and fed throughout development on standard diets with nicotine included at concentrations from 0 to 1000 μg/100 g diet. Overall mortality across all nicotine treatments was low, averaging 9.8% at the prepupal stage and 18.1% at the white-eyed pupal stage, but survival was significantly reduced by nicotine. The mass of prepupae and white-eyed pupae was not affected by nicotine. In terms of body composition, nicotine affected water content but did not influence either protein or lipid stores of white-eyed pupae. We attribute the absence of consistent negative effects of dietary nicotine to detoxification mechanisms in developing honeybees, which enable them to resist both natural and synthetic xenobiotics. [ABSTRACT FROM AUTHOR]

Highlights: [•] Apis mellifera scutellata apiaries were screened for pathogens and parasites. [•] In total, ten pathogens and parasites were detected in 13 apiaries over 14months. [•] BQCV was the most prevalent virus in honeybees. [•] First report of VDV-1 and IAPV in South Africa. [•] Varroa destructor was the most common parasite in A. m. scutellata apiaries. [ABSTRACT FROM AUTHOR]

Factors underlying the Allee effect are still heavily debated in ecology. For plants that rely on pollinators for seed production, decreases in conspecific aggregation may reduce attractiveness to floral visitors and lead to an Allee effect. However, floral visitors often differ in their pollination effectiveness; hence, the likelihood of an Allee effect in plant fecundity may depend on how various flower visitors respond to plant aggregation., We tested for Allee effects on fecundity of individuals across two years in the self-incompatible perennial, Kniphofia linearifolia Baker ( Xanthorrhoeaceae), which has two distinct types of pollinator, birds and native bees., For this, we used three measures of aggregation; population size, density and isolation. We made replicated pollinator observations in populations of various aggregations and quantified fecundity in these populations. To determine the differences in pollinator effectiveness and assess their contribution to fecundity, we selectively excluded bird visitors from K. linearifolia in these populations., We found that population size, but not density or isolation distance, was associated with increased bird abundance and seed set in one of the two years of the study. Bird visitation rate increased with increased plant aggregation within populations. Fruit set and seed set per flower were positively related to bird visitation rate. The difference in seed set per flower between bird-excluded and unmanipulated plants increased with increasing population size. Although birds were much less frequent visitors than bees (on average 2.1 visits plant−1 h−1 compared to 57.5 visits plant-1 h−1), selective exclusion experiments indicated that birds are consistently the more effective pollinators of this species, and therefore most likely to influence fecundity., Synthesis. In this system, characterised by an Allee effect on plant fecundity, birds were the most effective pollinators, responded positively to plant aggregation and were associated with increased fecundity. Therefore, the responses of effective pollinators to plant aggregation may be a factor that underlies Allee effects on plant fecundity. [ABSTRACT FROM AUTHOR]

* Premise of the study: Hermaphroditism in plants can lead to gender conflicts, such as pollen discounting--the loss of siring opportunities following self-pollination, and ovule discounting--the loss of seed production opportunities when self-pollen tubes disable ovules through early inbreeding depression or late-acting self-incompatibility. If ovules are discounted by self-pollination, it can be predicted that emasculation (removal of self-pollen) should increase seed production, as long as pollinators are not deterred by emasculation. * Methods: Using the hermaphroditic Kniphofia linearifolia, which belongs to a lineage known to possess late-acting self-incompatibility, we performed hand-pollinations with either self- or cross-pollen and recorded pollen tube growth and seed production. We paired experimentally emasculated plants with non-emasculated controls and quantified pollinator visitation rates, fruit, and seed set in both groups. * Key Results: Ovules penetrated by tubes from self-pollen uniformly failed to develop into seeds, as expected from ovarian self-incompatibility (or strong early inbreeding depression). Experimental emasculation had no effect on the rate of visitation by birds, the primary pollinators of this species, but led to increased rejection by bees, which are secondary pollinators. Despite reducing visitation by some pollinators, emasculation led to increased seed production and reduced rates of seed abortion. * Conclusions: These results show that female performance in hermaphroditic flowers can be enhanced when flowers are emasculated, even if the overall number of pollinator visits is decreased. The most likely explanation for this effect of emasculation is that it reduces ovule discounting arising from pollinator-mediated self-pollination. [ABSTRACT FROM AUTHOR]

Livestock farming in the Eastern Cape, South Africa is a common land use practice that has affected the biodiversity of plants and animals in the region negatively. Indigenous populations of wild honey bee ( Apis mellifera) colonies also may suffer. Recently, farmers in the Eastern Cape have been converting their farms to game reserves as ecotourism attractions and nature conservation lands. Consequently, the goal of this research was to determine if land use habits (livestock farming and conversion to game reserves) in the Eastern Cape affect honey bee colony population density and colony strength parameters. A series of indices were developed to compare the relative population densities of colonies in two or more areas by counting the number of foraging bees and number of bee lines established at feeding stations. Wild colonies on farms and reserves were located and sampled to determine land use effects on colony strength parameters including total area of comb in the colony, the area of comb containing stored honey, pollen, and brood, adult bee population, weight per bee, and the colony nest cavity volume ratio. When viewed collectively, the data indicated that land use practices have affected honey bee nesting dynamics in the Eastern Cape. Trends in the data suggested that colonies nesting on the reserves may occur in greater densities than those nesting on livestock farms, though they do not appear to be healthier. Hopefully, this work will be continued since honey bee conservation in areas where they are native is crucial to the health of agriculture and whole ecosystems globally. [ABSTRACT FROM AUTHOR]

Abstract: Recent large-scale mortality of honeybee colonies is believed to be caused by multiple interactions between diseases, parasites, pesticide exposure, and other stress factors. To test whether a dual challenge has an additive effect in reducing survival, we experimentally stimulated the immune system of caged Apis mellifera scutellata workers from six colonies by injecting saline or Escherichia coli lipopolysaccharides (LPS), and additionally fed them the alkaloid nicotine (0μM, 3μM and 300μM in 0.63M sucrose). Workers did not increase their sucrose intake to compensate for the immune system activation, and those injected with E. coli LPS decreased their intake on the highest nicotine concentration. In the single challenges, injection and high nicotine doses negatively affected survival. All injected worker groups showed reduced survival. Without nicotine, survival of the saline and E. coli LPS worker groups was similar, but survival of E. coli LPS-challenged workers dropped below that of the saline groups when additionally challenged by nicotine, with bees dying earlier at higher nicotine concentrations. In the dual challenge of saline injection and dietary nicotine, a reduced effect on survival was observed, with lower mortality than expected from the summed mortalities due to the single challenges. However, additive and synergistic effects on survival were observed in workers simultaneously challenged by E. coli LPS and nicotine, indicating that interactive effects of simultaneous pathogen exposure and dietary toxin are detrimental to honeybee fitness. [Copyright &y& Elsevier]

To test the hypothesis that the honeybee hybrid zone in South Africa is a tension zone due to increased reproductive conflict in colonies that contain both Apis mellifera capensis and Apis mellifera scutellata worker genotypes, we constructed mixed subspecies and hybrid colonies via a combination of artificial and natural matings. We measured emergence weight, ovary activation, and the presence/absence of a spermatheca on workers of different genotypes. We show that the measured characteristics were all affected by genotype with some traits also affected by the social environment in which the worker was reared. Workers with both an A. m. capensis mother and father had the highest emergence weight. When workers had an A. m. capensis mother, paternity affected emergence weight with A. m. capensis fathers producing heavier workers. When the queen was A. m. scutellata, paternity had less effect on weight. Presence of spermatheca was highest in mixed colonies irrespective of maternity and colonies containing pure A. m. capensis workers only. Paternity had a significant effect on the presence of a spermatheca within mixed colonies, with workers that had an A. m. capensis father being more likely to possess a spermatheca. Rates of ovary activation were highest in colonies with an A. m. scutellata queen mated to drones of both genotypes, suggesting that mixed subspecies colonies likely suffer increased reproductive strife among workers. Our results provide support for the hypothesis that the South African honeybee hybrid zone is a tension zone arising from reduced fitness of genetically mixed colonies. [ABSTRACT FROM AUTHOR]

Abstract: Secondary metabolites produced by plants for herbivore defence are often found in floral nectar, but their effect on the foraging behaviour and physiological performance of pollinators is largely unknown. Nicotine is highly toxic to most herbivores, and nicotine-based insecticides may contribute to current pollinator declines. We examined the effects of nectar nicotine on honeybee foraging choices and worker longevity. Free-flying honeybee (Apis mellifera scutellata) workers from six colonies were given a choice between multiple nicotine concentrations (0–1000μM) in artificial nectar (0.15–0.63M sucrose). The dose-dependent deterrent effect of nicotine was stronger in lower sugar concentrations, but even the highest nicotine concentrations did not completely repel honeybees, i.e. bees did not stop feeding on these diets. Nicotine in nectar acts as a partial repellent, which may keep pollinators moving between plants and enhance cross-pollination. In the second part of the study, newly emerged workers from 12 colonies were caged and fed one of four nicotine concentrations (0–300μM) in 0.63M sucrose for 21days. Moderate (⩽30μM) nicotine concentrations had no significant detrimental effect, but high nicotine concentrations reduced the survival of caged workers and their nectar storage in the honey comb. In contrast, worker groups that survived poorly on sugar-only diets demonstrated increased survival on all nicotine diets. In the absence of alternative nectar sources, honeybees tolerate naturally occurring nectar nicotine concentrations; and low concentrations can even be beneficial to honeybees. However, high nicotine concentrations may have a detrimental effect on colony fitness. [Copyright &y& Elsevier]

The nutritional needs of bees are supplied by nectar carbohydrates and by protein and other nutrients in pollen but little is known of how bees achieve nutritional balance. Using newly emerged caged worker honeybees (Apis mellifera scutellata), we investigated whether bees maintain their intake target when confined to pairs of imbalanced complementary diets varying in protein to carbohydrate (P:C) ratio. Diets were formulated using three protein sources [casein, royal jelly or Feed-Bee® (a natural pollen substitute)] and sucrose. Within each protein type, honeybees switched between complementary diets and converged on the same P:C intake target. However, this target differed between protein types: P:C ratios were 1:12, 1:14 and 1:11 on casein, royal jelly and Feed-Bee® diets, respectively. Except for an early peak in protein consumption on royal jelly diets, these strongly convergent ratios remained constant over the 14 day experiment. This is probably due to the absence of brood, reflected in relatively stable values measured for haemolymph protein concentration and hypopharyngeal gland activation in bees on Feed- Bee® diets. Performance of caged workers was also assessed in terms of survival and ovarian activation. Survival was highest on casein diets and lowest on Feed~Bee® diets but ovarian activation was highest on royal jelly diets and lowest on casein diets. This may be due to additional components in Feed~Bee® and royal jelly (e.g. fatty acids), which are needed to activate the ovaries but also reduce survival. Nutrient intake of broodless workers is directly related to their own physiological requirements, and the strong carbohydrate bias may reflect the high metabolic rate of honeybees even under resting conditions. [ABSTRACT FROM AUTHOR]

Pollen is unique among floral rewards in functioning as both a carrier of gametes and an attractant and nutritious resource for floral visitors. Animals that collect pollen without pollinating (pollen thieves) could reduce siring success of thieved plants and cause pollen limitation of seed set at the population level; however, such impacts on plant reproduction have not been demonstrated experimentally. To test these effects we added hives of native honey bees (Apis mellifera scutellata) to populations of a primarily bird-pollinated plant, Aloe maculata, in eastern South Africa. In field and aviary trials, bee addition increased pollen removal from anthers but decreased pollen deposition on stigmas, and so reduced both male and female pollination components. Further, total seed production decreased with hive addition in the aviary experiment and in three of four field populations, indicating that population-level pollen theft can also compromise reproductive success. In the field, naturally occurring allodapine bees also seemed to act as pollen thieves, outweighing the effect of honey bee hive addition at one of the four aloe populations. Our results highlight the importance of social bees as pollen thieves, even of plants that have evolved in their presence, and the role of dichogamy in promoting pollen theft. Given the commonness of both social bees and dichogamy, pollen theft is likely a much more common influence on floral ecology and evolution than suggested by the sparse literature. [ABSTRACT FROM AUTHOR]

Abstract: Terrestrial organisms need to limit evaporation from their bodies in order to maintain a homeostatic water balance. Owing to a large surface to volume ratio, arthropods are particularly susceptible to desiccation and have evolved behavioural and physiological mechanisms to conserve water. In social insects, water balance is also affected by the interactions between nestmates and by the architecture of the nest. For honeybees, humidity is particularly important for the brood because it affects the hatching success of eggs and because, unlike ants, honeybees cannot relocate their brood to parts of the nest with more favourable humidity. To advance the understanding of the water economy in honeybee nests, we investigated whether workers exhibit a hygropreference when exposed to a gradient of 24–90% relative humidity (RH) and whether the expression of this preference and their behaviour is affected by the presence of brood. The results show that young honeybee workers in the absence of brood exhibit a weak hygropreference for approximately 75% RH. When brood is present the expression of this preference is further weakened, suggesting that workers tend to the brood by distributing evenly in the gradient. In addition, fanning behaviour is shown to be triggered by an increase in humidity above the preferred level but not by a decrease. Our results suggest that humidity in honeybee colonies is actively controlled by workers. [Copyright &y& Elsevier]

Estimating the population size of social bee colonies in the wild is often difficult because nests are highly cryptic. Because of the honeybee ( Apis mellifera) mating behaviour, which is characterized by multiple mating of queens at drone congregation areas (DCA), it is possible to use genotypes of drones caught at these areas to infer the number of colonies in a given region. However, DCAs are difficult to locate and we assess the effectiveness of an alternative sampling technique to determine colony density based on inferring male genotypes from queen offspring. We compare these methods in the same population of wild honeybees, Apis mellifera scutellata. A set of linked microsatellite loci is used to decrease the frequency of recombination among marker loci and therefore increase the precision of the estimates. Estimates of population size obtained through sampling of queen offspring is significantly larger than that obtained by sampling drones at DCAs. This difference may be due to the more extensive flying range of queens compared with drones on mating flights. We estimate that the population size sampled through queen offspring is about double that sampled through drones. [ABSTRACT FROM AUTHOR]

Abstract: Protein-rich diets are known to promote ovarian and egg development in workers of the honeybee, Apis mellifera, even in the presence of a queen. Since the main source of protein for honeybees is pollen, its quality and digestibility might be important dietary factors determining reproductive capacity. We have compared the effect of two types of pollen—sunflower, Helianthus annuus, and aloe, Aloe greatheadii var davyana—on ovarian development in A. mellifera scutellata workers. Under queenright conditions in the field, worker bees exhibited greater ovarian development when feeding on aloe pollen than on sunflower pollen. In their midgut, we observed higher extraction efficiency for aloe (80%) than for sunflower (69%) pollen. This may be attributed to the morphology and size of the two kinds of pollen grains and explains, together with the high protein content of aloe pollen (32% dry mass in bee-collected pollen) compared to sunflower pollen (15%), why aloe pollen promoted higher ovarian development. However, in the laboratory workers sustained on aloe pollen had significantly less-developed ovaries and higher mortality than those fed sunflower pollen. These detrimental effects may be due to an unbalanced protein:carbohydrate ratio. We discuss the effects of unbalanced diets on the physiology and ecology of honeybee reproduction. [Copyright &y& Elsevier]

Abstract: Aloe greatheadii var. davyana is the most important indigenous South African bee plant. Fresh, bee-collected and stored pollen of this aloe was collected and analysed for its nutritional content, including amino acid and fatty acid composition. Highly significant differences were found between the three types of pollen. Collection and storage by the bees resulted in increased water (13–21% wet weight) and carbohydrate content (35–61% dry weight), with a resultant decrease in crude protein (51–28% dry weight) and lipid content (10–8% dry weight). Essential amino acids were present in equal or higher amounts than the required minimum levels for honeybee development, with the exception of tryptophan. Fatty acids comprised a higher proportion of total lipid in fresh pollen than in bee-collected and stored pollen. This study is the first to compare the changes that occur in pollen of a single species after collection by honeybees. [Copyright &y& Elsevier]

Abstract: In 1990 the Africanized honey bee, a descendent of Apis mellifera scutellata, was identified in south Texas [Hunter, L.A., Jackman, J.A., Sugden, E.A., 1992. Detection records of Africanized honey bees in Texas during 1990, 1991 and 1992. Southwestern Entomol. 18, 79–89]. The potential impact of this immigrant on feral and managed colonies was the subject of considerable speculation. The goal of this study was to investigate the diversity of feral honey bee races in pine forest landscapes of east Texas, subsequent to immigration of A. m. scutellata. The specific objectives were (i) to assess the immigration of A. m. scutellata into east Texas pine forest landscapes and (ii) to evaluate the suitability of the pine forest landscape to feral honey bees. This mesoscale landscape study was conducted on the Sam Houston National Forest in east Texas. Swarm traps and aerial pitfall traps were used to monitor feral honey bees. Spatial databases were used to evaluate suitability of the pine forest landscape for honey bees. Scoring mitochondrial DNA type (mitotypes), we found representatives of A. mellifera scutellata, eastern European, western European, and A. mellifera lamarckii races in pine forest landscapes of east Texas. The conclusions that follow from this aspect of the investigation are (i) honey bees are a ubiquitous component of the pine forest landscape in east Texas, (ii) mitotype diversity persists subsequent to the immigration of A. m. scutellata, and (iii) A. m. scutellata is an added element of the mitotype diversity in the landscape. To evaluate quantitatively the suitability of the pine forest to feral honey bees, we used a spatial database for the study area and FRAGSTATS. The landscape structure in 1256ha units surrounding six swarms of honey bees captured in the swarm traps was examined. The metrics used to characterize the kind, number, size, shape, and configuration of elements forming the landscape, defined a heterogeneous environment for honey bees that included sufficient food and habitat resources needed for survival, growth, and reproduction. The conclusions that follow from this aspect of the investigation are (1) although classified as a pine forest, management practices and other human activities have altered the landscape and thereby created food and habitat resources suitable for honey bees, (2) the forestry practices associated specifically with road corridor maintenance, stream side corridor protection, RCW management, and Wilderness Area management introduce structural heterogeneity to the forest landscape which enriches the diversity and abundance of early successional flowering plants and provides cavity sites needed by honey bees, (3) ranching, farming, and urbanization within the study area also create these conditions, and (4) based on inferences from melissopalynology, honey bees provide pollination services for a broad representation of native and introduced flowering plant species of the pineywoods ecoregion. [Copyright &y& Elsevier]

Um levantamento quali-quantitativo dos estágios sucessionais que constituem a vegetação arbórea existente na área localizada na sede campestre da associação dos apicultores na região de União da Vitória (Paraná-Brasil), foi realizado por meio de amostragem aleatória. A caracterização estrutural da floresta foi executada através dos valores de densidade, freqüência, dominância e valor de importância das espécies. A vegetação herbácea foi descrita em termos qualitativos. As plantas de interesse apícola, e que justificaram a realização do trabalho, foram destacadas nos resultados, apresentando-se o valor apícola estimado para cada qual. As árvores que têm valor apícola no estágio médio somaram 179,24 pontos e no estágio avançado 174,45 pontos. O Syagrus romanzoffiana foi a espécie com maior valor apícola.

The African honey bee subspecies Apis mellifera scutellata has colonized much of the Americas in less than 50 years and has largely replaced European bees throughout its range in the New World. The African bee therefore provides an excellent opportunity to examine the factors that influence invasion success. We provide a synthesis of recent research on the African bee, concentrating on its ability to displace European honey bees. Specifically, we consider (a) the genetic composition of the expanding population and the symmetry of gene flow between African and European bees, (b) the mechanisms that favor the preservation of the African genome, and (c) the possible range and impact of the African bee in the United States. [ABSTRACT FROM AUTHOR]

High-fidelity PCR of 16S rRNA sequences was used to identify bacteria associated with worker adults of the honeybee subspecies Apis mellifera capensis and Apis mellifera scutellata. An expected &ap;1.5-kb DNA band, representing almost the entire length of the 16S rRNA gene, was amplified from both subspecies and cloned. Ten unique sequences were obtained: one sequence each clustered with Bifidobacterium (Gram-positive eubacteria), Lactobacillus (Gram-positive eubacteria), and Gluconacetobacter (Gram-negative α-proteobacteria); two sequences each clustered with Simonsiella (β-proteobacteria) and Serratia (γ-proteobacteria); and three sequences each clustered with Bartonella (α-proteobacteria). Although the sequences relating to these six bacterial genera initially were obtained from either A. m. capensis or A. m. scutellata or both, newly designed honeybee-specific 16S rRNA primers subsequently amplified all sequences from all individual workers of both subspecies. Attempts to amplify these sequences from eggs have failed. However, the wsp primers designed to amplify Wolbachia DNA from arthropods, including these bees, consistently produced a 0.6-kb DNA band from individual eggs, indicating that amplifiable bacterial DNA was present. Hence, the 10 bacteria could have been acquired orally from workers or from other substrates. This screening of 16S rRNA sequences from A. m. capensis and A. m. scutellata found sequences related to Lactobacillus and Bifidobacterium which previously had been identified from other honeybee subspecies, as well as sequences related to Bartonella, Gluconacetobacter, Simonsiella/Neisseria, and Serratia, which have not been identified previously from honeybees. [Copyright &y& Elsevier]