Rediscovery of Apis vechti Maa, 1953: The Saban Honey Bee

The species Apis Vechti (MAA, 1953) the Sabah honey bee is organized as a valid species. Additional to the description of MAA (1953) species-specific characters associated with the endophallus, hind leg tibial hair of the drone and worker bee fore-wing venation are described

Evidence for convergent nucleotide evolution and high allelic turnover rates at the complementary sex determiner (csd) gene of western and Asian honey bees

Our understanding of the impact of recombination, mutation, genetic drift and selection on the evolution of a single gene is still limited. Here we investigate the impact of all of these evolutionary forces at the complementary sex determiner (csd) gene which evolves under a balancing mode of selection. Females are heterozygous at the csd gene and males are hemizygous; diploid males are lethal and occur when csd is homozygous. Rare alleles thus have a selective advantage, are seldom lost by the effect of genetic drift and are maintained over extended periods of time when compared to neutral polymorphisms. Here, we report on the analysis of 17, 19 and 15 csd alleles of Apis cerana, Apis dorsata and Apis mellifera honey bees respectively. We observed great heterogeneity of synonymous (pi S) and nonsynonymous (pi N) polymorphisms across the gene, with a consistent peak in exon 6 and 7. We propose that exons 6 and 7 encode the potential specifying domain (csd-PSD) which has accumulated elevated nucleotide polymorphisms over time by balancing selection. We observed no direct evidence that balancing selection favors the accumulation of nonsynonymous changes at csd-PSD (pi N/pi S ratios are all < 1, ranging from 0.6 to 0.95). We observed an excess of shared nonsynonymous changes, which suggests that strong evolutionary constraints are operating at csd-PSD resulting in the independent accumulation of the same nonsynonymous changes in different alleles across species (convergent evolution). Analysis of a csd-PSD genealogy revealed relatively short average coalescence times (~6 million years), low average synonymous nucleotide diversity (pi S < 0.09) and a lack of trans-specific alleles which substantially contrasts with previously analyzed loci under strong balancing selection. We excluded the possibility of a burst of diversification after population bottlenecking and intragenic recombination as explanatory factors, leaving high turn-over rates as the explanation for this observation. By comparing observed allele richness and average coalescence times with a simplified model of csd-coalescence, we found that small long term population sizes (i.e. Ne <104), but not high mutation rates, can explain short maintenance times, implicating a strong impact of genetic drift on the molecular evolution of highly social honey bees

A simple and distinctive microbiota exclusively associated with honey bees and bumble bees

Abstract: Specialized relationships with bacteria often allow animals to exploit a new diet by providing a novel set of metabolic capabilities. Bees are a monophyletic group of Hymenoptera that transitioned to a completely herbivorous diet from the carnivorous diet of their wasp ancestors. Recent culture-independent studies suggest that a set of distinctive bacterial species inhabits the gut of the honey bee, Apis mellifera. Here we survey the gut microbiotae of diverse bee and wasp species to test whether acquisition of these bacteria was associated with the transition to herbivory in bees generally. We found that most bee species lack phylotypes that are the same or similar to those typical of A. mellifera, rejecting the hypothesis that this dietary transition was symbiont-dependent. The most common bacteria in solitary bee species are a widespread phylotype of Burkholderia and the pervasive insect associate, Wolbachia. In contrast, several social representatives of corbiculate bees do possess distinctive bacterial phylotypes. Samples of A. mellifera harboured the same microbiota as in previous surveys, and closely related bacterial phylotypes were identified in two Asian honey bees (Apis andreniformis and Apis dorsata) and several bumble bee (Bombus) species. Potentially, the sociality of Apis and Bombus species facilitates symbiont transmission and thus is key to the maintenance of a more consistent gut microbiota. Phylogenetic analyses provide a more refined taxonomic placement of the A. mellifera symbionts. apis mellifera | bacterial microbiota | insect symbiosis | microbiology | molecula

Drone competition at drone congregation areas in four Apis species

In Apis mellifera the estimated average number of drones visiting a drone congregation area (DCA) was 11 750 + 2 145. Drones of the species Apis cerana, A. koschevnikovi, A. dorsata and A. mellifera, which pursued a queen dummy moving in circular course, flew in a comet shaped formation. Median numbers of drones in a comet ranged from 9 drones (A. koschevnikovi) to 31 drones (A. mellifera). In none of the species we observed aggression between drones. Drone density behind the queen and distance to the queen seemed to be adjusted to avoid collisions between drones. The median flight speed ranged from 2.6 m/s (A. koschevnikovi) to 4.1 m/s (A. dorsata). The median duration of a drone’s presence in the mating comet did not exceed 2 seconds. Drones of all species had the ability of high acceleration (10 to 20 m/s2). Either by overtaking or leaving/entering the comet drones seem to compete for more promising positions. Only drones flying in a limited space of not more than 2000 cm3 behind the queen were successful in grasping the dummy

Variance in spermatozoa number among Apis dorsata drones and among Apis mellifera drones

Published estimates of the mean spermatozoa numbers for Apis dorsata drones vary from 1.2 × 106 and 2.4 × 106; the number of spermatozoa per individual drone vary from 0.22 × 106 to 2.65 × 106. Counts presented here revealed 1.19 × 106 + 0.25 × 106 spermatozoa in drones sampled near a colony and 1.59 × 106 + 0.18 × 106 in drones sampled at a drone congregation area (DCA) in Sabah, Borneo. The difference between the two sites is significant. Further, the degree of variation in sperm numbers among drones near the colonies was higher than at the DCA. Possible reasons are discussed for spermatozoa number variation between drone samples in A. dorsata and in A. mellifera (published estimates). Furthermore, it is discussed if differences in spermatozoa numbers among fathering males may contribute to differences in patriline proportions within colonies

Mating flights and sperm transfer in the dwarf honeybee Apis andreniformis (Smith, 1858)

Mating flights of 3 virgin queens of Apis andreniformis were observed at their natural nesting site. They initiated mating flights between 12.33 and 12.50 h. The flight duration was between 19 and 23 minutes. The sting chamber of the returning queens contained the orange-colored secretion from the cornual gland of the drone's endophallus. Immediately after the mating flights, the queens were dissected. No sperm was detected in the oviducts, but spermatozoa were found in the spermathecae. In 2 queens, the spermathecae contained 0.09 million spermatozoa, which corresponds to about 75 The third queen had 0.31 million spermatozoa. The spermatozoa in the spermatheca were observed to be moving, and formed an undulating thread. These results suggest that sperm is transferred not into the oviducts but directly into the spermatheca (via the spermaduct). Seven egg-laying queens of unknown age had between 0.33 and 1.26 million spermatozoa in their spermathecae. The mode of sperm transfer is discussed in relation to the number and sequence of the spermatozoa received from each drone in the spermatheca.Vols de fécondation et transfert de sperme chez l'abeille naine, Apis andreniformis (Smith, 1858). L'abeille naine Apis andreniformis n'a été redécouverte comme espèce propre qu'en 1987 [CITE]. Depuis les études de biologie comparée avec les autres espèces d'Apis ont été nombreuses. Nous décrivons ici les vols de fécondation des reines et le mode de transfert du sperme. Six colonies ont été trouvées dans les plantations de cacaoyers de la Station Expérimentale d'Agriculture de Tenom, Sabah, en Malaisie. Une colonie possédait sept cellules royales ; elles ont été prélevées et placées en étuve. Toutes les reines ont éclos. Les colonies avec les jeunes reines ont été observées de 9.30 à 16.00 h. Lorsque la reine rentrait d'un vol de fécondation, elle était immédiatement capturée et disséquée. Dans les dix minutes qui suivaient, l'une des reines écloses en étuve était introduite dans la colonie. Nous avons pu observer les vols de fécondation de trois reines. Les reines se sont envolées pendant la principale période de vol des mâles, entre 12.33 et 12.50 h. Le vol durait entre 19 et 24 min (Tab. I). Toutes les reines avaient dans la chambre de l'aiguillon la secrétion de couleur orange des cornules de l'endophallus du mâle (Fig. 1), qui peut donc être considérée comme un signe de fécondation. Les reines ont été disséquées entre cinq et dix minutes après leur retour dans la colonie. Aucun sperme n'a été trouvé dans les oviductes, mais les spermathèques renfermaient entre 0,09 et 0,31 millions de spermatozoïdes (Tab. II). Ils bougeaient et formaient un ruban ondulant en forme d'anneau. Dans la spermathèque qui renfermait 0,31 million de spermatozoïdes, il y avait deux anneaux (Fig. 2). D'après ces résultats le transfert de sperme a eu lieu, comme chez A. florea, directement dans le canal de la spermathèque et non pas dans les oviductes, comme c'est le cas chez les espèces d'Apis qui nidifient dans des cavités. Les spermathèques de sept reines pondeuses d'âge inconnu renfermaient entre 0,33 et 1,26 million de spermatozoïdes qui étaient toujours répartis régulièrement. Le faible nombre de spermatozoïdes chez les reines qui ne s'étaient accouplées qu'une fois pourrait s'expliquer par le fait qu'habituellement elles effectuent plusieurs vols de fécondation. Il est aussi possible que le nombre de mâles présents ait été trop faible. Deux des reines fraichement fécondées possédaient 0,09 million de spermatozoïdes, ce qui ne représente que 70 % des spermatozoïdes produits dans les vésicules séminales d'un mâle. La spermathèque de la troisième reine renfermait 0,31 million de spermatozoïdes, soit 79 % des spermatozoïdes produits par trois mâles. Si l'on prend pour base le nombre moyen des accouplements [CITE], le nombre moyen de spermatozoïdes dans les vésicules séminales [CITE] et celui dans les spermathèques des reines pondeuses (Tab. III), 40 % environ des spermatozoïdes d'un mâle atteignent la spermathèque de la reine chez A. andreniformis. Si l'on considère les accouplement effectifs, c'est 66 % . D'après les résultats de notre étude nous estimons que 70 à 80 % des spermatozoïdes des trois premiers mâles qui s'accouplent avec une reine atteignent sa spermathèque. Lors des accouplements chez les espèces d'Apis qui nidifient dans des cavités, les spermatozoïdes parviennent d'abord dans les oviductes. Puis, durant plus de 24 h, a lieu le transfert dans la spermathèque, au cours duquel seuls 3 à 10 % des spermatozoïdes reçus atteignent la spermathèque. Dans le cas du transfert du sperme dans le canal de la spermathèque (A. florea, A. andreniformis), le remplissage de la spermathèque est achevé dès que la reine rentre de son vol de fécondation. La reine dispose alors moins d'une demi-heure pour influencer le remplissage de sa spermathèque. Le mode de transfert du sperme pourrait avoir une influence sur le nombre de spermatozoïdes et sur l'ordre dans lequel les spermatozoïdes des divers mâles atteignent la spermathèque

Using drones for estimating colony number by microsatellite DNA analyses of haploid males in Apis

In social insects the number of colonies rather than the actual number of individuals in the population primarily determines the effective population size. Here we present a method where microsatellite data of haploid males can be used to estimate the number of male producing queens in honeybee populations. A cluster analysis based on the allelic identity by descent (AID) among male genotypes is used to group potential brother males. For each “brother cluster” the corresponding mother queen genotype is determined by Mendelian inference. We show in various simulations that although limited number of screened loci can result in slightly biased estimates, the precision improves considerably with increasing number of loci. Empirical data from microsatellite studies of the Western honeybee Apis mellifera and the giant Asian honeybee Apis dorsata are presented to illustrate the application of the procedure

Mites from debris and sealed brood cells of Apis dorsata colonies in Sabah (Borneo) Malaysia, including a new haplotype of Varroa jacobsoni

In the debris of five Apis dorsata colonies at a single site in Sabah, Borneo we found the mites Tropilaelaps clareae, Tropilaelaps koenigerum, Varroa rindereri, Varroa jacobsoni and Euvarroa wongsirii. Most were T. clareae, but T. koenigerum were also quite common. The V. rindereri specimens belonged to the same haplotype as described previously from A. koschevnikovi from Borneo. However, the V. jacobsoni belonged to a new haplotype, which we named the `Borneo 2 haplotype of V. jacobsoni'. Of the mites detected in the debris, 84% of the T. clareae and 57% of the T. koenigerum were damaged. Inspection of 1673 brood cells of two A. dorsata colonies at the same site resulted in adult T. clareae and T. koenigerum together with their offspring (nymphs). The percentage of infested drone and worker cells did not differ, nor did the number of mites per cell: 6.0 $\pm$ 1.6 in worker brood and 6.1 $\pm$ 1.9 in drone brood (n = 10). We found no Varroa mites in the inspected brood cells, suggesting that the mites do not reproduce in A. dorsata and indicating that interspecific mite transfer occurs between sympatric Apis species in Borneo