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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2009.08.007 Byline: Nadine C. Chapman, James Makinson, Madeleine Beekman, Benjamin P. Oldroyd Abstract: To protect their colonies from robbing by conspecifics, honeybees have evolved nest-guarding behaviour. Guards adjust their acceptance threshold so that, as the likelihood of robbing increases, fewer non-nestmates are admitted. In addition to the possibility of robbing, queenless colonies may be infiltrated by reproductively parasitic non-nestmates. We tested the hypothesis that queenless colonies would be more discriminatory of non-nestmates than queenright colonies. As predicted, queenless colonies accepted significantly fewer non-nestmates (from queenright colonies) than they did nestmates, whereas queenright colonies did not differentiate significantly between the two sources. This trend continued once laying workers became active in queenless colonies. Thus there is evidence that queenless colonies are more discerning against potential reproductive parasites than queenright colonies. We also tested the hypothesis that as the likelihood of an intruder being a reproductive parasite increased, guards would become less permissive of allowing it entrance to the colony. Queenright colonies accepted significantly more non-nestmates from queenright colonies (no active ovaries) than they did non-nestmates from queenless colonies (many with active ovaries). However, queenless colonies did not make this distinction. We suggest that to queenless colonies all non-nestmates are potential parasites. Author Affiliation: Behaviour and Genetics of Social Insects Laboratory, School of Biological Sciences A12, University of Sydney, Australia Article History: Received 5 May 2009; Revised 12 June 2009; Accepted 10 August 2009 Article Note: (miscellaneous) MS. number: 09-00287R

It is often necessary to assess the density of honey bee colonies in an environment. In theory, a random sample of males obtained at a mating lek (Drone Congregation Area) can be used to infer the number of queens that contributed sons to the sample, and thereby estimate colony density based on the area from which drones are drawn to a DCA. Because of its utility and efficiency, the technique is being increasingly used. However, the accuracy of the method has never been evaluated, and there are no recommendations for sample size.Here, we infer the genotypes of 322 mother queens from the genotypes of 2329 drones caught at a single DCA using the program COLONY. We then use this realistic pool of queen genotypes to generate multiple simulated data sets of drone genotypes, varying the number of queens and sons that each queen contributed to the sample.We find that the technique provides an accurate estimate (<10% error) of the total number of families present in a drone sample, provided that queens contribute at least six drones to the sample on average. This threshold can be reduced when colony density is low. Non‐sampling error only becomes significant when queens contribute fewer than three sons on average across simulated samples.We conclude that the technique is robust and can be used with confidence provided that the sample size is adequate. [ABSTRACT FROM AUTHOR]

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 (k e) 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 k e 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 k e > 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. [ABSTRACT FROM AUTHOR]

Inbreeding (the mating between closely related individuals) often has detrimental effects that are associated with loss of heterozygosity at overdominant loci, and the expression of deleterious recessive alleles. However, determining which loci are detrimental when homozygous, and the extent of their phenotypic effects, remains poorly understood. Here, we utilize a unique inbred population of clonal (thelytokous) honey bees, Apis mellifera capensis, to determine which loci reduce individual fitness when homozygous. This asexual population arose from a single worker ancestor approximately 20 years ago and has persisted for at least 100 generations. Thelytokous parthenogenesis results in a 1/3 of loss of heterozygosity with each generation. Yet, this population retains heterozygosity throughout its genome due to selection against homozygotes. Deep sequencing of one bee from each of the three known sub‐lineages of the population revealed that 3,766 of 10,884 genes (34%) have retained heterozygosity across all sub‐lineages, suggesting that these genes have heterozygote advantage. The maintenance of heterozygosity in the same genes and genomic regions in all three sub‐lineages suggests that nearly every chromosome carries genes that show sufficient heterozygote advantage to be selectively detrimental when homozygous. [ABSTRACT FROM AUTHOR]

Across the world, the keeping of stingless bees is increasingly popular, providing commercial pollination, high-value honey and a rewarding pass time. The popularity of stingless beekeeping has resulted in large-scale anthropogenic movements of nests, sometimes from outside their native range. Colony movement has the potential to impact local populations via transfer of parasites and pathogens and gene flow across unnaturally large geographic scales. Tetragonula carbonaria is the most widespread and commonly kept stingless bee species in Australia. Concerns have been raised that large-scale artificial propagation of T. carbonaria colonies by Sydney beekeepers, from a small number of colonies that originated in south-east Queensland, may have two consequences. First, the managed population may be becoming increasingly inbred. Second, the wild population may be experiencing significant introgression of south-east Queensland genotypes, potentially diluting local adaptations to the Sydney environment and resulting in the loss of local alleles. Here we show, based on microsatellite and mitochondrial markers, that both the managed and wild Sydney populations are significantly different from the south-east Queensland population. Nonetheless there is evidence that introgression of south-east Queensland alleles is impacting the genetic structure of both wild and managed Sydney populations. The two Sydney populations are indistinguishable, suggesting two-way gene flow in Sydney consistent with expectations of gene flow via male dispersal. All populations have low inbreeding coefficients, suggesting that they are genetically healthy. [ABSTRACT FROM AUTHOR]

Epigenetic modifications, mediated by DNA methylation, are involved in caste differentiation between queen and worker honey bees, Apis mellifera. This study uses methylation sensitive amplified fragment length polymorphism (MS-AFLP) to investigate whether genome-wide DNA methylation is implicated in the regulation of honey bee worker sterility and whether CO2 narcosis, which suppresses ovary activation in queenless workers, influences DNA methylation. Queenless workers were divided into control and experimental (CO2 narcosis) cages. We compared MS-AFLP patterns in CO2-treated and non-treated workers with and without activated ovaries at 4 h, 2 and 7 days after treatment. While there was evidence of DNA methylation in all samples, there was no detectable difference in genome-wide methylation patterns between any treatment comparisons. This suggests that mechanisms that regulate worker sterility in the adult honey bee worker are not related to genome-wide methylation, and that CO2 narcosis does not significantly affect DNA methylation patterns in the worker ovary. However, because DNA methylation is sparse in the honey bee, and because MS-AFLP detects only a proportion of methylated sites, it remains possible that a subset of genes that are responsible for the regulation of worker sterility are differentially methylated, but that we failed to pick these up in our genome-wide scan. [ABSTRACT FROM AUTHOR]

Author(s): Piyamas Nanork [1, 2, 3]; Jürgen Paar [2]; Nadine C. Chapman [2]; Siriwat Wongsiri [1]; Benjamin P. Oldroyd (corresponding author) [2] The queen of a honeybee colony has a [...]