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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

Introduced species are a significant global concern because they can disrupt native ecosystems and cause economic damage to agricultural systems and infrastructure. The mitochondrial DNA (mtDNA) diversity of invasive populations can help to identify the source and number of incursions and reveal whether these populations have maintained standing genetic variation that might allow mitochondrial genomes to adapt to new environments. We investigated mitochondrial diversity in native and invasive populations of the Asian honey bee (Apis cerana). We generated 144 sequences of mitochondrial cytochrome c oxidase subunit I (COI) from samples spanning three invasive populations (Australia, New Guinea and Solomon Islands) and three native‐range Indonesian populations (Java, Sulawesi and Flores). We then analysed these sequences together with published COI sequences to evaluate changes in mtDNA diversity associated with the recent spread of A. cerana across the Austral‐Pacific region. Mitochondrial COI diversity was consistent with invasive A. cerana populations having endured severe founder event bottlenecks during colonisation of New Guinea from Java, and then again during colonisation of Australia and the Solomon Islands from New Guinea. Mitochondrial diversity of native‐range Indonesian populations was high (26 COI haplotypes detected), particularly on Java (20 haplotypes), while all samples from invasive populations carried the same COI haplotype. Indeed, the single COI haplotype of invasive A. cerana populations is consistent with invasive populations being founded by just one, or very few, queens, as previously suggested from nuclear markers. Further investigation is needed to understand the fitness effects, if any, of mitochondrial diversity loss in invasive A. cerana populations of the Austral‐Pacific. [ABSTRACT FROM AUTHOR]

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]

Functional worker sterility is the defining feature of insect societies. Yet, workers are sometimes found reproducing in their own or foreign colonies. The proximate mechanisms underlying these alternative reproductive phenotypes are keys to understanding how reproductive altruism and selfishness are balanced in eusocial insects. In this study, we show that in honeybee ( Apis mellifera) colonies, the social environment of a worker, that is, the presence and relatedness of the queens in a worker's natal colony and in surrounding colonies, significantly influences her fertility and drifting behaviour. Furthermore, subfamilies vary in the frequency of worker ovarian activation, propensity to drift and the kind of host colony that is targeted for reproductive parasitism. Our results show that there is an interplay between a worker's subfamily, reproductive state and social environment that substantially affects her reproductive phenotype. Our study further indicates that honeybee populations show substantial genetic variance for worker reproductive strategies, suggesting that no one strategy is optimal under all the circumstances that a typical worker may encounter. [ABSTRACT FROM AUTHOR]

All too often, studies of sexual selection focus exclusively on the responses in one sex, on single traits, typically those that are exaggerated and strongly sexually dimorphic. They ignore a range of less obvious traits and behavior, in both sexes, involved in the interactions leading to mate choice. To remedy this imbalance, we analyze a textbook example of sexual selection in the stalk-eyed fly ( Diasemopsis meigenii). We studied several traits in a novel, insightful, and efficient experimental design, examining 2,400 male-female pairs in a 'round-robin' array, where each female was tested against multiple males and vice versa. In D. meigenii, females exhibit strong mate preference for males with highly exaggerated eyespan, and so we deliberately constrained variation in male eyespan to reveal the importance of other traits. Males performing more precopulatory behavior were more likely to attempt to mate with females and be accepted by them. However, behavior was not a necessary part of courtship, as it was absent from over almost half the interactions. Males with larger reproductive organs (testes and accessory glands) did not make more mating attempts, but there was a strong tendency for females to accept mating attempts from such males. How females detect differences in male reproductive organ size remains unclear. In addition, females with larger eyespan, an indicator of size and fecundity, attracted more mating attempts from males, but this trait did not alter female acceptance. Genetic variation among males had a strong influence on male mating attempts and female acceptance, both via the traits we studied and other unmeasured attributes. These findings demonstrate the importance of assaying multiple traits in males and females, rather than focusing solely on prominent and exaggerated sexually dimorphic traits. The approach allows a more complete understanding of the complex mating decisions made by both males and females. [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]

The honeybee, Apis mellifera, is the world's most important pollinator and is ubiquitous in most agricultural ecosystems. Four major evolutionary lineages and at least 24 subspecies are recognized. Commercial populations are mainly derived from subspecies originating in Europe (75-95%). The Africanized honeybee is a New World hybrid of A. m. scutellata from Africa and European subspecies, with the African component making up 50-90% of the genome. Africanized honeybees are considered undesirable for bee-keeping in most countries, due to their extreme defensiveness and poor honey production. The international trade in honeybees is restricted, due in part to bans on the importation of queens (and semen) from countries where Africanized honeybees are extant. Some desirable strains from the United States of America that have been bred for traits such as resistance to the mite Varroa destructor are unfortunately excluded from export to countries such as Australia due to the presence of Africanized honeybees in the USA. This study shows that a panel of 95 single nucleotide polymorphisms, chosen to differentiate between the African, Eastern European and Western European lineages, can detect Africanized honeybees with a high degree of confidence via ancestry assignment. Our panel therefore offers a valuable tool to mitigate the risks of spreading Africanized honeybees across the globe and may enable the resumption of queen and bee semen imports from the Americas. [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 [...]

Due to the introduction of exotic honey bee (Apis mellifera L.) diseases in the eastern states, the borders of the state of Western Australia were closed to the import of bees for breeding and other purposes >25 yr ago. To provide genetically improved stock for the industry, a closed population breeding program was established that now provides stock for the majority of Western Australian beekeepers. Given concerns that inbreeding may have resulted from the closed population breeding structure, we assessed the genetic diversity within and between the breeding lines by using microsatellite and mitochondrial markers. We found that the breeding population still maintains considerable genetic diversity, despite 25 yr of selective breeding. We also investigated the genetic distance of the closed population breeding program to that of beekeepers outside of the program, and the feral Western Australian honey bee population. The feral population is genetically distinct from the closed population, but not from the genetic stock maintained by beekeepers outside of the program. The honey bees of Western Australia show three mitotypes, originating from two subspecies: Apis mellifera ligustica (mitotypes C1 and M7b) and Apis mellifera iberica (mitotype M6). Only mitotypes C1 and M6 are present in the commercial populations. The feral population contains all three mitotypes. [ABSTRACT FROM AUTHOR]