Queen Genotypes Research Articles

Meta-analysis of genetic diversity and intercolony relatedness among reproductives in commercial honey bee populations.

Honey bee colonies are large kin groups, each with a single mother queen and thousands of female workers. Queen bees are highly polyandrous, each mating with an average of approximately 12 drones from other colonies. We used a meta-analysis approach to compare the pedigree relationships of honey bee reproductives (queens and their mates) across five different studies and to quantify the overall genetic diversity of breeding populations. We compared the inferred genotypes of queens and their mates from microsatellite analyses of worker offspring from a feral Africanized honey bee population (which served as a negative control for inbreeding), an experimentally derived population of sister queens (which served as a positive control for inbreeding), and three separate commercially managed populations. We then compared the relatedness of all drones mated to each queen (mate-mate), all queens within each population (queen-queen), each queen with each of her mates (queen-mate), and all drones within each population (drone-drone). We found, as expected, the lowest levels of genetic similarity in the outcrossed population and highest levels of genetic similarity in the inbred population. Levels of genetic similarity among the managed honey bee populations were intermediate but closer to that of the inbred population. Genetic structuring of the entire breeding population resulted in two major subpopulations, likely deriving from breeders on the east and west coast. The effects that these findings have on the overall population genetic diversity of managed honey bees is discussed.

Identification of runs of homozygosity in Western honey bees (Apis mellifera) using whole-genome sequencing data.

Runs of homozygosity (ROH) are continuous homozygous segments that arise through the transmission of haplotypes that are identical by descent. The length and distribution of ROH segments provide insights into the genetic diversity of populations and can be associated with selection signatures. Here, we analyzed reconstructed whole-genome queen genotypes, from a pool-seq data experiment including 265 Western honeybee colonies from Apis mellifera mellifera and Apis mellifera carnica. Integrating individual ROH patterns and admixture levels in a dynamic population network visualization allowed us to ascertain major differences between the two subspecies. Within A. m. mellifera, we identified well-defined substructures according to the genetic origin of the queens. Despite the current applied conservation efforts, we pinpointed 79 admixed queens. Genomic inbreeding (F ROH) strongly varied within and between the identified subpopulations. Conserved A. m. mellifera from Switzerland had the highest mean F ROH (3.39%), while queens originating from a conservation area in France, which were also highly admixed, showed significantly lower F ROH (0.45%). The majority of A. m. carnica queens were also highly admixed, except 12 purebred queens with a mean F ROH of 2.33%. Within the breed-specific ROH islands, we identified 14 coding genes for A. m. mellifera and five for A. m. carnica, respectively. Local adaption of A. m. mellifera could be suggested by the identification of genes involved in the response to ultraviolet light (Crh-BP, Uvop) and body size (Hex70a, Hex70b), while the A. m. carnica specific genes Cpr3 and Cpr4 are most likely associated with the lighter striping pattern, a morphological phenotype expected in this subspecies. We demonstrated that queen genotypes derived from pooled workers are useful tool to unravel the population dynamics in A. mellifera and provide fundamental information to conserve native honey bees.

Reconstructing queen genotypes by pool sequencing colonies in eusocial insects: Statistical Methods and their application to honeybee.

Eusocial insects are crucial to many ecosystems, and particularly the honeybee (Apis mellifera). One approach to facilitate their study in molecular genetics, is to consider whole-colony genotyping by combining DNA of multiple individuals in a single pool sequencing experiment. Cheap and fast, this technique comes with the drawback of producing data requiring dedicated methods to be fully exploited. Despite this limitation, pool sequencing data have been shown to be informative and cost-effective when working on random mating populations. Here, we present new statistical methods for exploiting pool sequencing of eusocial colonies in order to reconstruct the genotypes of the queen of such colony. This leverages the possibility to monitor genetic diversity, perform genomic-based studies or implement selective breeding. Using simulations and honeybee real data, we show that the new methods allow for a fast and accurate estimation of the queen's genetic ancestry, with correlations of about 0.9 to that obtained from individual genotyping. Also, it allows for an accurate reconstruction of the queen genotypes, with about 2% genotyping error. We further validate these inferences using experimental data on colonies with both pool sequencing and individual genotyping of drones. In brief, in this study we present statistical models to accurately estimate the genetic ancestry and reconstruct the genotypes of the queen from pool sequencing data from workers of an eusocial colony. Such information allows to exploit pool sequencing for traditional population genetics analyses, association studies and for selective breeding. While validated in Apis mellifera, these methods are applicable to other eusocial hymenopterans.

Linked supergenes underlie split sex ratio and social organization in an ant

Sexually reproducing organisms usually invest equally in male and female offspring. Deviations from this pattern have led researchers to new discoveries in the study of parent-offspring conflict, genomic conflict, and cooperative breeding. Some social insect species exhibit the unusual population-level pattern of split sex ratio, wherein some colonies specialize in the production of future queens and others specialize in the production of males. Theoretical work predicted that worker control of sex ratio and variation in relatedness asymmetry among colonies would cause each colony to specialize in the production of one sex. While some empirical tests supported theoretical predictions, others deviated from them, leaving many questions about how split sex ratio emerges. One factor yet to be investigated is whether colony sex ratio may be influenced by the genotypes of queens or workers. Here, we sequence the genomes of 138 Formica glacialis workers from 34 male-producing and 34 gyne-producing colonies to determine whether split sex ratio is under genetic control. We identify a supergene spanning 5.5 Mbp that is closely associated with sex allocation in this system. Strikingly, this supergene is adjacent to another supergene spanning 5 Mbp that is associated with variation in colony queen number. We identify a similar pattern in a second related species, Formica podzolica. The discovery that split sex ratio is determined, at least in part, by a supergene in two species opens future research on the evolutionary drivers of split sex ratio.

Nuclear and mitochondrial markers: molecular characterization of Africanized Apis mellifera queens as royal jelly producers

Apis mellifera scutellata was introduced in Brazil in 1956. This subspecies originated from Africanized polyhybrid honey bees (A. mellifera), and quickly spread due to its high adaptability, reproductive behavior, foraging ability, and defensiveness. Good management practices have been developed that allow for good beekeeping performance of this introduced subspecies in Brazil. The selection of queens that produce royal jelly has made it possible to identify molecular markers to select the best matrices for the development of bee breeding programs to increase royal jelly production. We evaluated the ability of different major royal jelly protein-3 (mrjp3) microsatellite markers to verify the polymorphism of selected royal jelly-producing queens, as well as the mitochondrial DNA haplotypes of these queens to identify their African or European origin. We verified the maternal origins of the honey bee workers in eight colony matrices of Africanized A. mellifera belonging to a breeding program of FEI, UEM aimed at producing royal jelly. Analyses were performed for the identification of microsatellite mrjp3 markers in the nuclear DNA, and restriction fragment length polymorphism polymerase chain reaction (RFLP-PCR) was used to search for markers in the mtDNA (mitochondrial DNA). Six alleles were found for the mrjp3 locus, and it was possible to use these to infer the genotypes of queens from seven colonies. Throughout the selection period, the main alleles (C, D, and E) remained present in the genomes of queens producing royal jelly. Queens selected for royal jelly production contained a predominance of African mtDNA. Microsatellite markers and mtDNA can be used in bee breeding programs to ensure the genetic origin of the queens used and verify the efficiency of Africanized A. mellifera bee breeding programs.

Using trapped drones to assess the density of honey bee colonies: a simulation and empirical study to evaluate the accuracy of the method

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.

Tool for genomic selection and breeding to evolutionary adaptation: Development of a 100K single nucleotide polymorphism array for the honey bee.

High‐throughput high‐density genotyping arrays continue to be a fast, accurate, and cost‐effective method for genotyping thousands of polymorphisms in high numbers of individuals. Here, we have developed a new high‐density SNP genotyping array (103,270 SNPs) for honey bees, one of the most ecologically and economically important pollinators worldwide. SNPs were detected by conducting whole‐genome resequencing of 61 honey bee drones (haploid males) from throughout Europe. Selection of SNPs for the chip was done in multiple steps using several criteria. The majority of SNPs were selected based on their location within known candidate regions or genes underlying a range of honey bee traits, including hygienic behavior against pathogens, foraging, and subspecies. Additionally, markers from a GWAS of hygienic behavior against the major honey bee parasite Varroa destructor were brought over. The chip also includes SNPs associated with each of three major breeding objectives—honey yield, gentleness, and Varroa resistance. We validated the chip and make recommendations for its use by determining error rates in repeat genotypings, examining the genotyping performance of different tissues, and by testing how well different sample types represent the queen's genotype. The latter is a key test because it is highly beneficial to be able to determine the queen's genotype by nonlethal means. The array is now publicly available and we suggest it will be a useful tool in genomic selection and honey bee breeding, as well as for GWAS of different traits, and for population genomic, adaptation, and conservation questions.

Multi-year genetic sampling indicates maternal gene flow via colony emigrations in the army ant Eciton burchellii parvispinum

Sex-biased dispersal occurs when one sex disperses more frequently or farther than the opposite sex. In ants, dispersal is often male biased and males typically contribute more strongly to gene flow within and among ant populations. However, army ants may offer an exceptional case of female-biased dispersal, because army ant colonies (particularly species in the Neotropical genus Eciton) routinely emigrate among nest sites. We hypothesized that maternal mobility via successive colony emigrations would reduce the relative male bias in dispersal, and that emigrations would contribute to gene flow within an Eciton population. We genotyped workers (highly variable DNA microsatellite loci) from Eciton burchellii parvispinum colonies collected over a 10 × 10 km area in Monteverde, Costa Rica. Samples were spaced approximately 3 years apart (in 2006 and 2009), the typical time between colony reproductive bouts. We used worker genotypes to reconstruct the genotypes of their mother queens and of a subset of the males that sired the workers. We then analyzed the population genetic structure of the queen and male genotypes by comparing individual-based relatedness estimates for each sex across geographic distance and over time. There was no significant difference in spatial genetic structure between the sexes, either within or between the 2006 and 2009 samples. There was some evidence against genetic philopatry: 2009 queens were significantly unrelated to 2006 queens collected nearby (within 0.5 km). The patterns suggest maternal dispersal via emigrations contributes to gene flow, reducing or eliminating male biases in dispersal. From two populations, we estimated average queen dispersal distance to be 0.63–1.04 km, a greater distance than many winged ant queens disperse. Because emigrations over the lifetime of army ant queens may contribute to gene flow across the landscape, habitat connectivity should be maintained to permit colony emigrations and support genetic diversity in populations of this keystone species.

İlkbahar ve Yaz Mevsiminde Yetiştirilen, Çiftleştirme Kutularında ve Banka Kolonilerinde Depolanan Ana Arıların Maiyet Feromonlarının Belirlenmesi

Bu çalışmada, çiftleştirme kutularında ve banka kolonilerinde depolanan Kafkas ve Anadolu arısı Ege ekotipi ana arıların maiyet feromonları (9-ODA, 9 HDA, HOB, HVA, metil oeat, koniferil alkol, setil alkol ve linolenik asit) belirlenmiştir. Ana arılardan ilk grubu yumurtlamaya başladıktan 102 gün sonra ependorf tüplerine tek tek toplanmış ve -20°C‘de analize kadar depolanmıştır (A grubu). Çiftleştirme kutusundan aynı gün toplanan ikinci grup ana arılar (10 Ege ve 10 Kafkas) banka kolonisinde 25 gün depolanmıştır (B grubu). Son grubu (C grubu) oluşturan ana arılar (10 Ege ve 10 Kafkas) ise, yumurtlamaya başladıktan 352 gün sonra çiftleştirme kutularından toplanmıştır. Bu sürelerin sonunda B ve C grubu ana arıları tek tek ependorf tüplerine alınarak -20°C‘de analize kadar depolanmıştır. Depolanan ana arının baş, göğüs ve karın kısmında gaz kromotografi ile maiyet feromonları belirlenmiştir. Bulgulara göre, ana arı yetiştirme mevsimi, uygulama grupları (A, B ve C) ve genotipler bakımından 9 ODA ve 9 HDA değerleri arasındaki farklar önemsiz, vücut kısımları arasındaki farklılıklar ise önemli bulunmuştur. Ana arı yetiştirme mevsimi, uygulama grupları, genotip ve vücut kısımları bakımından HOB ve HVA değerleri arasındaki farklar da önemsiz olarak bulunmuştur. Araştırmada linolenik asit miktarı üzerinde uygulama grubunun, genotipin ve vücut kısımlarının etkilerinin önemli olduğu belirlenmiştir. Linolenik asitin ana arının karın kısmında, baş ve göğüs kısmına göre daha fazla salgılandığı ve farkların önemli olduğu belirlenmiştir. Genel olarak 9 ODA ve 9 HDA miktarları en yüksek ana arının baş kısmından, HOB ve HVA ise vücudun üç bölümünde eşit miktarlarda, linolenik asit ise en fazla karın kısmından salgılanmıştır. Çiftleştirme kutularında 352 gün yumurtlamasına izin verilen ana arılar, 102 gün yumurtlamasına izin verilen ve bankalanan ana arılara göre daha çok 9 ODA, 9 HDA, HOB, HVA salgılamışlardır.

The role of epistatic interactions underpinning resistance to parasitic Varroa mites in haploid honey bee (Apis mellifera) drones.

The Red Queen hypothesis predicts that host-parasite coevolutionary dynamics can select for host resistance through increased genetic diversity, recombination and evolutionary rates. However, in haplodiploid organisms such as the honeybee (Apis mellifera), models suggest the selective pressure is weaker than in diploids. Haplodiploid sex determination, found in A.mellifera, can allow deleterious recessive alleles to persist in the population through the diploid sex with negative effects predominantly expressed in the haploid sex. To overcome these negative effects in haploid genomes, epistatic interactions have been hypothesized to play an important role. Here, we use the interaction between A.mellifera and the parasitic mite Varroa destructor to test epistasis in the expression of resistance, through the inhibition of parasite reproduction, in haploid drones. We find novel loci on three chromosomes which explain over 45% of the resistance phenotype. Two of these loci interact only additively, suggesting their expression is independent of each other, but both loci interact epistatically with the third locus. With drone offspring inheriting only one copy of the queen's chromosomes, the drones will only possess one of two queen alleles throughout the years-long lifetime of the honeybee colony. Varroa, in comparison, completes its highly inbred reproductive cycle in a matter of weeks, allowing it to rapidly evolve resistance. Faced with the rapidly evolving Varroa, a diversity of pathways and epistatic interactions for the inhibition of Varroa reproduction could therefore provide a selective advantage to the high levels of recombination seen in A.mellifera. This allows for the remixing of phenotypes despite a fixed queen genotype.

Evidence of Selective Mating and Triploidy Among Two Social Forms ofSolenopsis invicta(Hymenoptera: Formicidae)

Summary A number of important behavioral and physiological traits distinguish both social forms of Solenopsis invicta Buren (Hymenoptera: Formicidae) and correlate with the Gp-9 locus within a supergene complex. These traits include fat body content, number of colony queens, dispersal, ability to initiate new colonies, size of workers, selective mortality, etc. Previous studies suggested gene flow between both social forms is unidirectional, with monogyne males mating almost exclusively with polygyne females. This study examined the genotypes of queens and their stored sperm during a mating flight in Florida where polygyne colonies predominate, and provides evidence of non-random mating; 84.6% of inseminated polygyne queens were mated to males of their own social form, and 92.4% of inseminated monogyne queens were mated by haploid males from monogyne colonies. Fertile, diploid males with unreduced sperm may be a cause for the high frequency of triploid BB alates (26.7%) and triploid polygyne alates (33.3%...

Extensive population admixture on drone congregation areas of the giant honeybee, Apis dorsata (Fabricius, 1793).

The giant honeybee Apis dorsata often forms dense colony aggregations which can include up to 200 often closely related nests in the same location, setting the stage for inbred matings. Yet, like in all other Apis species, A. dorsata queens mate in mid-air on lek like drone congregation areas (DCAs) where large numbers of males gather in flight. We here report how the drone composition of A. dorsata DCAs facilitates outbreeding, taking into the account both spatial (three DCAs) and temporal (subsequent sampling days) dynamics. We compared the drones’ genotypes at ten microsatellite DNA markers with those of the queen genotypes of six drone-producing colonies located close to the DCAs (Tenom, Sabah, Malaysia). None of 430 sampled drones originated from any of these nearby colonies. Moreover, we estimated that 141 unidentified colonies were contributing to the three DCAs. Most of these colonies were participating multiple times in the different locations and/or during the consecutive days of sampling. The drones sampled in the DCAs could be attributed to six subpopulations. These were all admixed in all DCA samples, increasing the effective population size an order of magnitude and preventing matings between potentially related queens and drones.

Fine-scale spatial genetic structure of common and declining bumble bees across an agricultural landscape.

Land-use changes have threatened populations of many insect pollinators, including bumble bees. Patterns of dispersal and gene flow are key determinants of species' ability to respond to land-use change, but have been little investigated at a fine scale (<10 km) in bumble bees. Using microsatellite markers, we determined the fine-scale spatial genetic structure of populations of four common Bombus species (B. terrestris, B. lapidarius, B. pascuorum and B. hortorum) and one declining species (B. ruderatus) in an agricultural landscape in Southern England, UK. The study landscape contained sown flower patches representing agri-environment options for pollinators. We found that, as expected, the B. ruderatus population was characterized by relatively low heterozygosity, number of alleles and colony density. Across all species, inbreeding was absent or present but weak (FIS = 0.01–0.02). Using queen genotypes reconstructed from worker sibships and colony locations estimated from the positions of workers within these sibships, we found that significant isolation by distance was absent in B. lapidarius, B. hortorum and B. ruderatus. In B. terrestris and B. pascuorum, it was present but weak; for example, in these two species, expected relatedness of queens founding colonies 1 m apart was 0.02. These results show that bumble bee populations exhibit low levels of spatial genetic structure at fine spatial scales, most likely because of ongoing gene flow via widespread queen dispersal. In addition, the results demonstrate the potential for agri-environment scheme conservation measures to facilitate fine-scale gene flow by creating a more even distribution of suitable habitats across landscapes.

Genetic evidence for landscape effects on dispersal in the army ant Eciton burchellii

Inhibited dispersal, leading to reduced gene flow, threatens populations with inbreeding depression and local extinction. Fragmentation may be especially detrimental to social insects because inhibited gene flow has important consequences for cooperation and competition within and among colonies. Army ants have winged males and permanently wingless queens; these traits imply male-biased dispersal. However, army ant colonies are obligately nomadic and have the potential to traverse landscapes. Eciton burchellii, the most regularly nomadic army ant, is a forest interior species: colony raiding activities are limited in the absence of forest cover. To examine whether nomadism and landscape (forest clearing and elevation) affect population genetic structure in a montane E.burchellii population, we reconstructed queen and male genotypes from 25 colonies at seven polymorphic microsatellite loci. Pairwise genetic distances among individuals were compared to pairwise geographical and resistance distances using regressions with permutations, partial Mantel tests and random forests analyses. Although there was no significant spatial genetic structure in queens or males in montane forest, dispersal may be male-biased. We found significant isolation by landscape resistance for queens based on land cover (forest clearing), but not on elevation. Summed colony emigrations over the lifetime of the queen may contribute to gene flow in this species and forest clearing impedes these movements and subsequent gene dispersal. Further forest cover removal may increasingly inhibit Eciton burchellii colony dispersal. We recommend maintaining habitat connectivity in tropical forests to promote population persistence for this keystone species.

Polygyny in the nest-site limited acacia-ant Crematogaster mimosae

Polygyny is common in social insects despite inevitable decreases in nestmate relatedness and reductions to the inclusive fitness returns for cooperating non-reproductive individuals. We studied the prevalence and mode of polygyny in the African acacia-ant Crematogaster mimosae. These ants compete intensively with neighboring colonies of conspecifics and with three sympatric ant species for resources associated with the whistling-thorn acacias in which they all obligately nest. We used the genotypes of alate males at ten microsatellite loci to reconstruct queen genotypes and found that C. mimosae colonies are frequently secondarily polygynous, in that they include multiple closely related (and sometimes full-sib) queens, and (more rarely) unrelated queens. We also found that individual queens in both monogynous and polygynous colonies had mated with multiple males, making C. mimosae an interesting example of simultaneous polygyny and polyandry. The presence of polygyny in C. mimosae and the intense competition for nest-sites between C. mimosae and its conspecifics support the association between nest-site limitation and polygyny. Polygyny may allow for increased worker populations and a competitive advantage, as inter-colony conflicts are typically won by the colony with the larger number of workers.

Potential increase in mating frequency of queens in feral colonies of Bombus terrestris introduced into Japan

With the exception of several species, bumblebees are monandrous. We examined mating frequency in feral colonies of the introduced bumblebee Bombus terrestris in Japan. Using microsatellite markers, genotyping of sperm DNA stored in the spermatheca of nine queens detected multiple insemination paternities in one queen; the others were singly mated. The average effective paternity frequency estimated from the genotypes of queens and workers was 1.23; that estimated from the workers' genotype alone was 2.12. These values were greater than those of laboratory-reared colonies in the native ranges of B. terrestris. The genotypes of one or two workers did not match those of their queens or showed paternities different from those of their nestmates; this may have arisen from either queen takeover or drifting of workers. These alien workers were responsible for the heterogeneous genotype distribution within each B. terrestris colony, resulting in higher estimates of paternity frequency than of insemination frequency. The high mating frequency of introduced B. terrestris may have occurred by artificial selection through mass breeding for commercialization. Moreover, polyandrous queens may be selectively advantageous, because reproduction by such queens is less likely to be disturbed by interspecific mating than that by monandrous queens.

Social Hybridogenesis in the Clonal Ant Cataglyphis hispanica

With a few rare exceptions, the vast majority of animals reproduce sexually. Some species have, however, evolved alternative modes of reproduction by shifting from classical bisexuality to unorthodox reproductive systems, like parthenogenesis, gynogenesis, or hybridogenesis. Under hybridogenesis, both the maternal and paternal genomes are expressed in somatic tissues, whereas the germline is purely maternal. Recently, a form of hybridogenesis at the level of the society has been reported in some ants, where purebred females develop into reproductive queens and interlineage hybrids into sterile workers. Here, we report a unique case of social hybridogenesis in the desert ant Cataglyphis hispanica. Workers are produced exclusively from interbreeding between two distinct genetic lineages, whereas male and female sexuals are produced by asexual reproduction through parthenogenesis. As a consequence, all workers are pure hybridogens, and only maternal genes are perpetuated from one generation to the next. Thus, queens of C. hispanica use sexual reproduction for colony growth, whereas they reproduce asexually through parthenogenesis for germline production.

Venom Alkaloid and Cuticular Hydrocarbon Profiles Are Associated with Social Organization, Queen Fertility Status, and Queen Genotype in the Fire Ant Solenopsis invicta

Queens in social insect colonies advertise their presence in the colony to: a) attract workers' attention and care; b) gain acceptance by workers as replacement or supplemental reproductives; c) prevent reproductive development in nestmates. We analyzed the chemical content of whole body surface extracts of adult queens of different developmental and reproductive stages, and of adult workers from monogyne (single colony queen) and polygyne (multiple colony queens) forms of the fire ant Solenopsis invicta. We found that the composition of the most abundant components, venom alkaloids, differed between queens and workers, as well as between reproductive and non-reproductive queens. Additionally, workers of the two forms could be distinguished by alkaloid composition. Finally, sexually mature, non-reproductive queens from polygyne colonies differed in their proportions of cis-piperidine alkaloids, depending on their Gp-9 genotype, although the difference disappeared once they became functional reproductives. Among the unsaturated cuticular hydrocarbons characteristic of queens, there were differences in amounts of alkenes/alkadienes between non-reproductive polygyne queens of different Gp-9 genotypes, between non-reproductive and reproductive queens, and between polygyne and monogyne reproductive queens, with the amounts increasing at a relatively higher rate through reproductive ontogeny in queens bearing the Gp-9 b allele. Given that the genotype-specific piperidine differences reflect differences in rates of reproductive maturation between queens, we speculate that these abundant and unique compounds have been co-opted to serve in fertility signaling, while the cuticular hydrocarbons now play a complementary role in regulation of social organization by signaling queen Gp-9 genotype.

Current distribution and population dynamics of the little fire ant supercolony in Cameroon

The little fire ant, Wasmannia auropunctata, is native to Central America, but has been introduced into many parts of the world. We examined the current distribution of W. auropunctata in Cameroon, tested for aggression between workers from different parts of the country, and examined the genotypes of workers, queens, and males to evaluate the mating system. We found W. auropunctata at 36 sites in three provinces (Centre, East, and South). We found W. auropunctata only in human-disturbed habitats. Its spread appears to be primarily human mediated. Aggressive behaviour was almost non-existent between workers from different sites, indicating that there is only one supercolony in Cameroon. Our genetic analysis found that only one male/female pair of clones was introduced into Cameroon, probably from Gabon. No new male clonal lineage was identified, whereas new sexually derived female clonal lineages were noted. Apart from the genotype of the founding queen, which was well distributed but generally not dominant, a new clonal queen genotype emerged and was both omnipresent and dominant at most sites. These results may be useful in the development of management strategies.

Mating frequency and genetic colony structure of the neotropical bumblebee Bombus wilmattae (Hymenoptera: Apidae)

So far, nearly all studies concerning the mating frequency of bumblebees have been conducted with temperate species, showing that single mating seems to be the predominant pattern in bumblebees. Studies involving tropical species, however, are still scarce. Here, we determined the mating frequency of queens of the tropical bumblebee species, Bombus wilmattae by using microsatellite genotyping based on a sample of nine colonies from Chiapas, Southern Mexico. A total of 204 workers were genotyped with microsatellite markers to infer the queen genotype and the number of males with which each queen had mated. Two of the nine queens were doubly mated and seven singly mated. In the colonies with the double-mated queens, the distribution of the patrilines was not even, resulting in effective mating frequencies of 1.34 and 1.70, respectively, and an average relatedness of g = 0.58 ± 0.06.