The Experts below are selected from a list of 168 Experts worldwide ranked by ideXlab platform
Benjamin P Oldroyd - One of the best experts on this subject based on the ideXlab platform.
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Genetic Diversity in the Progeny of Commercial Australian Queen Honey Bees (Hymenoptera: Apidae) Produced in Autumn and Early Spring
Journal of economic entomology, 2018Co-Authors: Nadine C. Chapman, Julianne Lim, Rani Dos Santos Cocenza, Benjamin Blanchard, Lucy M. Nguyen, Gabriele Buchmann, Benjamin P OldroydAbstract:Honey bee [Apis mellifera L. (Hymenoptera: Apidae)] Queens are polyandrous, mating with an average 12 males (drones). Polyandry has been shown to confer benefits to Queens and the colonies they head, including avoidance of inviable brood that can arise via sex locus homozygosity, increased resilience to pests and pathogens, and increased survival and productivity, leading to improved colony-level fitness. Queens with an effective mating frequency (ke) greater than 7 are considered adequately mated, whereas Queens that fall below this threshold head colonies that have increased likelihood of failure and may be less productive for beekeepers. We determined ke in Queens produced in early Spring and Autumn by five Australian commercial Queen producers to determine whether the Queens they produced were suitably mated. Drone populations are low at these times of year, and therefore, there is an increased risk that Queens would fall below the ke > 7 threshold. We found that 33.8% of Autumn-produced Queens did not meet the threshold, whereas 93.8% of Spring Queens were adequately mated. The number of colonies contributing drones to the mating pool was similarly high in both seasons, suggesting that although many colonies have drones, their numbers may be decreased in Autumn and management strategies may be required to boost drone numbers at this time. Finally, Queens had similar levels of homozygosity to workers, and inbreeding coefficients were very low, suggesting that inbreeding is not a problem.
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Honey bee (Apis mellifera) sperm competition in vitro - two are no less viable than one
Apidologie, 2017Co-Authors: Sharoni Shafir, Liz Kabanoff, Michael Duncan, Benjamin P OldroydAbstract:Sperm competition is the competition between sperm of different males for the fertilization of an ovum. Queen Honey Bees mate with many males over a short period, establishing ideal conditions in which sperm competition might occur. One hypothesized mechanism by which sperm competition may occur is via sperm incapacitation (SI), which involves the killing and/or inhibition of function of sperm from one male by sperm (or seminal fluid) of another male. However, there is very little empirical support for SI in any animal. We tested whether reported increases in mortality of Honey bee spermatozoa when semen from several drones is mixed can be attributed to SI. We found that when the collection method involves minimal manipulation, sperm viability is not reduced in samples of mixed semen from two drones relative to those of a single drone. Our results do not support the existence of SI by killing of sperm (during early encounter in vitro) between semen from unrelated drones, and suggest that reported reductions in sperm viability in mixed samples arise from mechanical damage during semen collection.
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Effects of natural mating and CO2 narcosis on biogenic amine receptor gene expression in the ovaries and brain of Queen Honey Bees, Apis mellifera.
Insect Molecular Biology, 2012Co-Authors: Vanina Vergoz, Michael Duncan, Julianne Lim, Guénaël Cabanes, Benjamin P OldroydAbstract:A Queen Honey bee mates at ~6 days of age, storing the sperm in her spermatheca for life. Mating is associated with profound changes in the behaviour and physiology of the Queen but the mechanisms underlying these changes are poorly understood. What is known is that the presence of semen in the oviducts and spermatheca is insufficient to initiate laying, and that copulation or CO2 narcosis is necessary for ovary activation. In this study we use real-time quantitative PCR to investigate the expression of biogenic amine receptor genes in the brain and ovarian tissue of Queens in relation to their reproductive status. We show that dopamine, octopamine and serotonin receptor genes are expressed in the ovaries of Queens, and that natural mating, CO2 narcosis, and the presence of semen in the spermatheca differentially affect their expression. We suggest that these changes may be central to the hormonal cascades that are necessary to initiate oogenesis.
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Honey bee ( Apis mellifera ) sperm competition in vitro — two are no less viable than one
Apidologie, 2009Co-Authors: Sharoni Shafir, Liz Kabanoff, Michael Duncan, Benjamin P OldroydAbstract:Sperm competition is the competition between sperm of different males for the fertilization of an ovum. Queen Honey Bees mate with many males over a short period, establishing ideal conditions in which sperm competition might occur. One hypothesized mechanism by which sperm competition may occur is via sperm incapacitation (SI), which involves the killing and/or inhibition of function of sperm from one male by sperm (or seminal fluid) of another male. However, there is very little empirical support for SI in any animal. We tested whether reported increases in mortality of Honey bee spermatozoa when semen from several drones is mixed can be attributed to SI. We found that when the collection method involves minimal manipulation, sperm viability is not reduced in samples of mixed semen from two drones relative to those of a single drone. Our results do not support the existence of SI by killing of sperm (during early encounter in vitro) between semen from unrelated drones, and suggest that reported reductions in sperm viability in mixed samples arise from mechanical damage during semen collection.
Michael Duncan - One of the best experts on this subject based on the ideXlab platform.
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Honey bee (Apis mellifera) sperm competition in vitro - two are no less viable than one
Apidologie, 2017Co-Authors: Sharoni Shafir, Liz Kabanoff, Michael Duncan, Benjamin P OldroydAbstract:Sperm competition is the competition between sperm of different males for the fertilization of an ovum. Queen Honey Bees mate with many males over a short period, establishing ideal conditions in which sperm competition might occur. One hypothesized mechanism by which sperm competition may occur is via sperm incapacitation (SI), which involves the killing and/or inhibition of function of sperm from one male by sperm (or seminal fluid) of another male. However, there is very little empirical support for SI in any animal. We tested whether reported increases in mortality of Honey bee spermatozoa when semen from several drones is mixed can be attributed to SI. We found that when the collection method involves minimal manipulation, sperm viability is not reduced in samples of mixed semen from two drones relative to those of a single drone. Our results do not support the existence of SI by killing of sperm (during early encounter in vitro) between semen from unrelated drones, and suggest that reported reductions in sperm viability in mixed samples arise from mechanical damage during semen collection.
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Effects of natural mating and CO2 narcosis on biogenic amine receptor gene expression in the ovaries and brain of Queen Honey Bees, Apis mellifera.
Insect Molecular Biology, 2012Co-Authors: Vanina Vergoz, Michael Duncan, Julianne Lim, Guénaël Cabanes, Benjamin P OldroydAbstract:A Queen Honey bee mates at ~6 days of age, storing the sperm in her spermatheca for life. Mating is associated with profound changes in the behaviour and physiology of the Queen but the mechanisms underlying these changes are poorly understood. What is known is that the presence of semen in the oviducts and spermatheca is insufficient to initiate laying, and that copulation or CO2 narcosis is necessary for ovary activation. In this study we use real-time quantitative PCR to investigate the expression of biogenic amine receptor genes in the brain and ovarian tissue of Queens in relation to their reproductive status. We show that dopamine, octopamine and serotonin receptor genes are expressed in the ovaries of Queens, and that natural mating, CO2 narcosis, and the presence of semen in the spermatheca differentially affect their expression. We suggest that these changes may be central to the hormonal cascades that are necessary to initiate oogenesis.
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Honey bee ( Apis mellifera ) sperm competition in vitro — two are no less viable than one
Apidologie, 2009Co-Authors: Sharoni Shafir, Liz Kabanoff, Michael Duncan, Benjamin P OldroydAbstract:Sperm competition is the competition between sperm of different males for the fertilization of an ovum. Queen Honey Bees mate with many males over a short period, establishing ideal conditions in which sperm competition might occur. One hypothesized mechanism by which sperm competition may occur is via sperm incapacitation (SI), which involves the killing and/or inhibition of function of sperm from one male by sperm (or seminal fluid) of another male. However, there is very little empirical support for SI in any animal. We tested whether reported increases in mortality of Honey bee spermatozoa when semen from several drones is mixed can be attributed to SI. We found that when the collection method involves minimal manipulation, sperm viability is not reduced in samples of mixed semen from two drones relative to those of a single drone. Our results do not support the existence of SI by killing of sperm (during early encounter in vitro) between semen from unrelated drones, and suggest that reported reductions in sperm viability in mixed samples arise from mechanical damage during semen collection.
Gene E. Robinson - One of the best experts on this subject based on the ideXlab platform.
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Senescence in the Worker Honey Bee Apis mellifera
Journal of insect physiology, 2007Co-Authors: Silvia C Remolina, Gene E. Robinson, Daniel M. Hafez, Kimberly A HughesAbstract:Honey Bees are social insects that exhibit striking caste-specific differences in longevity. Queen Honey Bees live on average 1-2 years, whereas workers live 2-6 weeks in the summer and about 20 weeks in the winter. It is not clear whether Queen-worker differences in longevity are due to intrinsic physiological differences in the rate of senescence, to differential exposure to extrinsic factors such as predation and adverse environmental conditions, or both. To determine if the relatively short lifespan of worker Bees involves senescence, we measured age-specific resistance to three different physiological stressors (starvation, thermal, and oxidative stress) while eliminating age-related differences in foraging activity and minimizing age-related differences in energy expenditure. Despite these manipulations, older worker Bees were still significantly less resistant to all three stressors than were younger Bees. These results indicate that the regulation of worker bee lifespan involves senescence, in addition to extrinsic factors.
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Central projections of sensory systems involved in Honey bee dance language communication.
Brain behavior and evolution, 2007Co-Authors: Axel Brockmann, Gene E. RobinsonAbstract:Honey bee dance language is a unique and complex form of animal communication used to inform nest mates in the colony about the specific location of food sources or new nest sites. Five different sensory systems have been implicated in acquiring and communicating the information necessary for dance language communication. We present results from neuronal tracer studies identifying the central projections from four of the five. Sensory neurons of the dorsal rim area of the compound eyes, involved in acquiring sun-compass based information, project to the dorsal-most part of the medulla. Sensory neurons of the neck hair plates, required to transpose sun-compass based information to gravity-based information in the dark hive, project to the dorsal labial neuromere of the subesophageal ganglion. Sensory neurons from the antennal joint hair sensilla and the Johnston's organ, which perceive information on dance direction and distance from mechanostimuli generated by abdomen waggling and wing vibration, project to the deutocerebral dorsal lobe and the subesophageal ganglion, and the posterior protocerebrum, respectively. We found no 'dance-specific' projections relative to those previously described for drone and Queen Honey Bees and other insect species that do not exhibit dance communication. We suggest that the evolution of dance language communication was likely based on the modification of central neural pathways associated with path integration, the capability to calculate distance, and directional information during flight.
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Vitellogenin, juvenile hormone, insulin signaling, and Queen Honey bee longevity
Proceedings of the National Academy of Sciences of the United States of America, 2007Co-Authors: Miguel Corona, Silvia C Remolina, Kimberly A Hughes, Rodrigo A. Velarde, Adrienne Moran-lauter, Ying Wang, Gene E. RobinsonAbstract:In most animals, longevity is achieved at the expense of fertility, but Queen Honey Bees do not show this tradeoff. Queens are both long-lived and fertile, whereas workers, derived from the same genome, are both relatively short-lived and normally sterile. It has been suggested, on the basis of results from workers, that vitellogenin (Vg), best known as a yolk protein synthesized in the abdominal fat body, acts as an antioxidant to promote longevity in Queen Bees. We explored this hypothesis, as well as related roles of insulin-IGF-1 signaling and juvenile hormone. Vg was expressed in thorax and head fat body cells in an age-dependent manner, with old Queens showing much higher expression than workers. In contrast, Vg expression in worker head was much lower. Queens also were more resistant to oxidative stress than workers. These results support the hypothesis that caste-specific differences in Vg expression are involved in Queen longevity. Consistent with predictions from Drosophila, old Queens had lower head expression of insulin-like peptide and its putative receptors than did old workers. Juvenile hormone affected the expression of Vg and insulin-IGF-1 signaling genes in opposite directions. These results suggest that conserved and species-specific mechanisms interact to regulate Queen bee longevity without sacrificing fecundity.
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Expansion of the neuropil of the mushroom bodies in male Honey Bees is coincident with initiation of flight
Neuroscience letters, 1997Co-Authors: Susan E. Fahrbach, Tugrul Giray, Sarah M. Farris, Gene E. RobinsonAbstract:The mushroom bodies (MB), the insect brain structures most often associated with learning, have previously been shown to exhibit structural plasticity during the adult behavioral development of female worker and Queen Honey Bees. We now show that comparable morphological changes occur in the brains of male Honey Bees (drones). The volume of the MB in the brains of drones was estimated from tissue sections using the Cavalieri method. Brains were obtained from six groups of drones that differed in age and flight experience. Circulating levels of juvenile hormone (JH) in these drones were determined by radioimmunoassay (RIA). There was an expansion of the neuropil of the MB that was temporally associated with drone behavioral development, as in female Queens and workers. The observed changes in drones were maintained in the presence of low levels of JH, also as in females. These results suggest that expansion of the neuropil of the MB in Honey Bees is associated with learning the location of the nest, because this learning is the most prominent aspect of behavioral development common to all members (workers, drones, Queen) of the Honey bee colony.
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Reproduction in worker Honey Bees is associated with low juvenile hormone titers and rates of biosynthesis
General and comparative endocrinology, 1992Co-Authors: Gene E. Robinson, Colette Strambi, Alain Strambi, Zhi Yong HuangAbstract:Three experiments were performed to determine the role of juvenile hormone (JH) in worker reproduction in Queenless colonies of Honey Bees. In Experiment 1, egg-laying workers had low hemolymph titers of JH, as did Bees engaged in brood care, while foragers had significantly higher titers. Experiment 2 confirmed these findings by demonstrating that laying workers have significantly lower rates of JH biosynthesis than foragers do. In Experiment 3, ovary development was inhibited slightly by application of the JH analog methoprene to 1-day-old Bees, but was not affected by application to older Bees, at least some already displaying egg-laying behavior. These results, which are consistent with earlier findings for Queen Honey Bees, are contrary to a common model of insect reproduction, in which elevated JH titers trigger ovary development, which then leads to oviposition. Previous experiments have demonstrated that JH regulates nonreproductive behavior in workers that is associated with colony division of labor; perhaps this function is incompatible with a traditional role for JH in reproduction.
Jeffery Pettis - One of the best experts on this subject based on the ideXlab platform.
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Sperm viability and gene expression in Honey bee Queens (Apis mellifera) following exposure to the neonicotinoid insecticide imidacloprid and the organophosphate acaricide coumaphos
Journal of Insect Physiology, 2016Co-Authors: Veeranan Chaimanee, Jay D. Evans, Yanping Chen, Caitlin Jackson, Jeffery PettisAbstract:Honey bee population declines are of global concern. Numerous factors appear to cause these declines including parasites, pathogens, malnutrition and pesticides. Residues of the organophosphate acaricide coumaphos and the neonicotinoid insecticide imidacloprid, widely used to combat Varroa mites and for crop protection in agriculture, respectively, have been detected in wax, pollen and comb samples. Here, we assess the effects of these compounds at different doses on the viability of sperm stored in the Honey bee Queens' spermatheca. Our results demonstrate that sub-lethal doses of imidacloprid (0.02ppm) decreased sperm viability by 50%, 7days after treatment. Sperm viability was a downward trend (about 33%) in Queens treated with high doses of coumaphos (100ppm), but there was not significant difference. The expression of genes that are involved in development, immune responses and detoxification in Honey bee Queens and workers exposed to chemicals was measured by qPCR analysis. The data showed that expression levels of specific genes were triggered 1day after treatment. The expression levels of P450 subfamily genes, CYP306A1, CYP4G11 and CYP6AS14 were decreased in Honey bee Queens treated with low doses of coumaphos (5ppm) and imidacloprid (0.02ppm). Moreover, these two compounds suppressed the expression of genes related to antioxidation, immunity and development in Queens at day 1. Up-regulation of antioxidants by these compounds in worker Bees was observed at day 1. Coumaphos also caused a repression of CYP306A1 and CYP4G11 in workers. Antioxidants appear to prevent chemical damage to Honey Bees. We also found that DWV replication increased in workers treated with imidacloprid. This research clearly demonstrates that chemical exposure can affect sperm viability in Queen Honey Bees.
Patrick Maes - One of the best experts on this subject based on the ideXlab platform.
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The Queen’s gut refines with age: longevity phenotypes in a social insect model
Microbiome, 2018Co-Authors: Kirk E. Anderson, Vincent A. Ricigliano, Brendon M. Mott, Duan C. Copeland, Amy S. Floyd, Patrick MaesAbstract:In social insects, identical genotypes can show extreme lifespan variation providing a unique perspective on age-associated microbial succession. In Honey Bees, short- and long-lived host phenotypes are polarized by a suite of age-associated factors including hormones, nutrition, immune senescence, and oxidative stress. Similar to other model organisms, the aging gut microbiota of short-lived (worker) Honey Bees accrue Proteobacteria and are depleted of Lactobacillus and Bifidobacterium, consistent with a suite of host senescence markers. In contrast, long-lived (Queen) Honey Bees maintain youthful cellular function with much lower expression of oxidative stress genes, suggesting a very different host environment for age-associated microbial succession. We sequenced the microbiota of 63 Honey bee Queens exploring two chronological ages and four alimentary tract niches. To control for genetic and environmental variation, we quantified carbonyl accumulation in Queen fat body tissue as a proxy for biological aging. We compared our results to the age-specific microbial succession of worker guts. Accounting for Queen source variation, two or more bacterial species per niche differed significantly by Queen age. Biological aging in Queens was correlated with microbiota composition highlighting the relationship of microbiota with oxidative stress. Queens and workers shared many major gut bacterial species, but differ markedly in community structure and age succession. In stark contrast to aging workers, carbonyl accumulation in Queens was significantly associated with increased Lactobacillus and Bifidobacterium and depletion of various Proteobacteria. We present a model system linking changes in gut microbiota to diet and longevity, two of the most confounding variables in human microbiota research. The pattern of age-associated succession in the Queen microbiota is largely the reverse of that demonstrated for workers. The guts of short-lived worker phenotypes are progressively dominated by three major Proteobacteria, but these same species were sparse or significantly depleted in long-lived Queen phenotypes. More broadly, age-related changes in the Honey bee microbiota reflect the regulatory anatomy of reproductive host metabolism. Our synthesis suggests that the evolution of colony-level reproductive physiology formed the context for host-microbial interactions and age-related succession of Honey bee microbiota.
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The Queen Gut Refines with Age: Longevity Phenotypes in a Social Insect Model
2018Co-Authors: Kirk E. Anderson, Vincent A. Ricigliano, Brendon M. Mott, Duan C. Copeland, Amy S. Floyd, Patrick MaesAbstract:AbstractBackgroundIn social insects, identical genotypes can show extreme lifespan variation providing a unique perspective on age-associated microbial succession. In Honey Bees, short and long-lived host phenotypes are polarized by a suite of age-associated factors including hormones, nutrition, immune senescence and oxidative stress. Similar to other model organisms, the aging gut microbiota of short-lived (worker) Honey Bees accrue Proteobacteria and are depleted of Lactobacillus and Bifidobacterium, consistent with a suite of host senescence markers. In contrast, long-lived (Queen) Honey Bees maintain youthful cellular function without expressing oxidative stress genes, suggesting a very different host environment for age-associated microbial succession.ResultsWe sequenced the microbiota of 63 Honey bee Queens exploring two chronological ages and four alimentary tract niches. To control for individual variation we quantified carbonyl accumulation in Queen fat body tissue as a proxy for biological aging. We compared our results to the age-specific microbial succession of worker guts. Accounting for Queen source variation, two or more bacterial species per niche differed significantly by Queen age. Biological aging in Queens was correlated with microbiota composition highlighting the relationship of microbiota with oxidative stress. Queens and workers shared many major gut bacterial species, but differ markedly in community structure and age succession. In stark contrast to aging workers, carbonyl accumulation in Queens was significantly associated with increased Lactobacillus and Bifidobacterium and depletion of various Proteobacteria.ConclusionsWe present a model system linking changes in gut microbiota to diet and longevity, two of the most confounding variables in human microbiota research. As described for other model systems, metabolic changes associated with diet and host longevity correspond to the changing microbiota. The pattern of age-associated succession in the Queen microbiota is largely the reverse of that demonstrated for workers. The guts of short-lived worker phenotypes are progressively dominated by three major Proteobacteria, but these same species were sparse or significantly depleted in long-lived Queen phenotypes. More broadly, our results suggest that lifespan evolution formed the context for host-microbial interactions and age-related succession of Honey bee microbiota.
