Queenless Honey Bee Colonies Research Articles

Quantity and Quality of Commercially Reared Queens as Affected by Number and Distribution of Artificially Grafted Queen Cells Within Queen-Less Honey Bee Colonies in the Middle Delta Region, Egypt

Quantity and Quality of Commercially Reared Queens as Affected by Number and Distribution of Artificially Grafted Queen Cells Within Queen-Less Honey Bee Colonies in the Middle Delta Region, Egypt

Effects of age and Reproductive Status on Tergal Gland Secretions in Queenless Honey bee Workers, Apis mellifera scutellata and A. m. capensis

Secretions from tergal glands are part of a queen's pheromonal control of worker reproduction in honey bees. However, in queenless honey bee colonies, workers compete to gain pheromonal, and hence reproductive dominance, over nestmates with ontogenetic changes in their glandular secretions that affect the behavioral or physiological responses of other individuals. Using gas chromatography/mass spectrometry, we investigated for the first time the age-dependent changes in tergal gland secretions of queenless workers of the clonal lineage of Apis mellifera capensis and workers of A. m. scutellata. The reproductive status of honey bee workers was determined by recording the presence of spermathecae and the level of ovarian activation. The tergal gland chemicals identified in both A. m. scutellata workers and A. m. capensis clone workers were oleic acid, n-tricosene, n-pentacosene, and n-heptacosene, with three additional compounds, palmitic acid, n-heneicosene, and n-nonacosene, in A. m. capensis clones. We report ethyl esters as new compounds from honey bee worker tergal gland profiles; these compounds increased in amount with age. All A. m. capensis clone workers dissected had spermathecae and showed ovarian activation from day 4, while ovarian activation only started on day 7 for A. m. scutellata workers that had no spermathecae. Tergal gland secretions were present in higher quantities in bees with activated, rather than inactive ovaries. This suggests that tergal gland secretions from reproductive workers could act as releaser and primer pheromones in synergy with other glandular compounds to achieve pheromonal and reproductive dominance.

Consumption of tyrosine in royal jelly increases brain levels of dopamine and tyramine and promotes transition from normal to reproductive workers in queenless honey bee colonies

Dopamine (DA) and tyramine (TA) have neurohormonal roles in the production of reproductive workers in queenless colonies of honey bees, but the regulation of these biogenic amines in the brain are still largely unclear. Nutrition is an important factor in promoting reproduction and might be involved in the regulation of these biogenic amines in the brain. To test this hypothesis, we examined the effect of oral treatments of tyrosine (Tyr; a common precursor of DA, TA and octopamine, and a component of royal jelly) in queenless workers and quantified the resulting production of biogenic amines. Tyrosine treatments enhanced the levels of DA, TA and their metabolites in the brain. Workers fed royal jelly had significantly larger brain levels of Tyr, DA, TA and the metabolites in the brains compared with those bees fed honey or sucrose (control). Treatment with Tyr also inhibited the behavior of workers outside of the hive and promoted ovarian development. These results suggest that there is a link between nutrition and the regulation of DA and TA in the brain to promote the production of reproductive workers in queenless honey bee colonies.

Genotypic diversity in queenless honey bee colonies reduces fitness

SummaryHoney bee queens mate with many males. The resulting genotypic diversity appears to enhance fitness of queenright colonies (those colonies with a reproductive queen present) which is difficult to measure, because measures of long-term fitness include successful matings of produced male sexuals (drones) and number of surviving swarms. The fitness of queenless colonies is, however, limited to worker-produced adult drones until natural colony death. Here we test the impact of genotypic diversity on fitness of queenless honey bee colonies, which were headed by queens inseminated with one, 10 and 20 drones or naturally mated. The data show that genetically diverse queenless colonies (20 subfamilies per colony) produced fewer adult drones, had a delayed onset of worker-derived drone flight activity, and a lower efficacy in drone production/per day colony life span compared to all other groups. Our data suggest that genotypic diversity may reduce fitness of queenless honey bee colonies, probably due to reproductive conflicts among subfamilies after queenloss.

Genome-wide analysis of alternative reproductive phenotypes in honeybee workers

A defining feature of social insects is the reproductive division of labour, in which workers usually forego all reproduction to help their mother queen to reproduce. However, little is known about the molecular basis of this spectacular form of altruism. Here, we compared gene expression patterns between nonreproductive, altruistic workers and reproductive, non-altruistic workers in queenless honeybee colonies using a whole-genome microarray analysis. Our results demonstrate massive differences in gene expression patterns between these two sets of workers, with a total of 1292 genes being differentially expressed. In nonreproductive workers, genes associated with energy metabolism and respiration, flight and foraging behaviour, detection of visible light, flight and heart muscle contraction and synaptic transmission were overexpressed relative to reproductive workers. This implies they probably had a higher whole-body energy metabolism and activity rate and were most likely actively foraging, whereas same-aged reproductive workers were not. This pattern is predicted from evolutionary theory, given that reproductive workers should be less willing to compromise their reproductive futures by carrying out high-risk tasks such as foraging or other energetically expensive tasks. By contrast, reproductive workers mainly overexpressed oogenesis-related genes compared to nonreproductive ones. With respect to key switches for ovary activation, several genes involved in steroid biosynthesis were upregulated in reproductive workers, as well as genes known to respond to queen and brood pheromones, genes involved in TOR and insulin signalling pathways and genes located within quantitative trait loci associated with reproductive capacity in honeybees. Overall, our results provide unique insight into the molecular mechanisms underlying alternative reproductive phenotypes in honeybee workers.

Pheromone-mediated reproductive dominance hierarchies among pseudo-clonal honeybee workers (Apis mellifera capensis)

Honey bee colonies are characterised by well-developed reproductive division of labour between the queen and workers. Here, we test whether this reproductive division of labour is evident in both the socially parasitic workers that invade a colony as well as in their offspring generation. We infected six Apis mellifera scutellata host colonies with pseudo-clonal socially parasitic Cape honeybee workers (Apis mellifera capensis). We show that the first generation of socially parasitic workers can monopolize reproduction within host colonies. Of the initially invading parasites, 94.4% became reproductive pseudoqueens with activated ovaries and produced queen-like pheromones. Their offspring, however, had much lower levels of ovary activation (3.1%), yet 89% showed fatty acid synthesis typical of the queen substance (9-oxo-2(E)-decenoic acid) biochemical pathway. However, in these second-generation workers, the last oxidation step from the precursor (9-hydroxy-2(E)-decenoic acid) to the queen substance was interrupted and appears to be required for reproductive dominance in honeybee workers. Our data show that despite the absence of genetic diversity, residual queen mandibular pheromone (QMP) variation is sufficient to establish reproductive dominance hierarchies among parasitic workers. Consequently, QMP produced by a group of workers can maintain reproductive division of labour in queenless honeybee colonies.

Intergenerational reproductive parasitism in a stingless bee

Insect colonies have been traditionally regarded as closed societies comprised of completely sterile workers ruled over by a single once-mated queen. However, over the past 15 years, microsatellite studies of parentage have revealed that this perception is far from the truth (Beekman & Oldroyd 2008). First, we learned that honey bee queens are far more promiscuous than we had previously imagined (Estoup et al. 1994), with one Apis dorsata queen clocked at over 100 mates (Wattanachaiyingcharoen et al. 2003). Then Oldroyd et al. (1994) reported a honey bee colony from Queensland, where virtually all the males were sons of a single patriline of workers - a clear case of a cheater mutant that promoted intra-colonial reproductive parasitism. Then we learned that both bumble bee colonies (Lopez-Vaamonde et al. 2004) and queenless honey bee colonies (Nanork et al. 2005, 2007) are routinely parasitized by workers from other nests that fly in and lay male-producing eggs that are then reared by the victim colony. There is even evidence that in a thelytokous honey bee population, workers lay female-destined eggs directly into queen cells, thus reincarnating themselves as a queen (Jordan et al. 2008). And let us not forget ants, where microsatellite studies have revealed equally bizarre and totally unexpected phenomena (e.g. Cahan & Keller 2003; Pearcy et al. 2004; Fournier et al. 2005). Now, in this issue, Alves et al. (2009) use microsatellites to provide yet another shocking and completely unexpected revelation about the nefarious goings-on in insect colonies: intergenerational reproductive parasitism by stingless bee workers.

Individual versus social pathway to honeybee worker reproduction (Apis mellifera): pollen or jelly as protein source for oogenesis?

Honeybee workers, Apis mellifera, can reproduce in queenless colonies. The production of queen-like pheromones may be associated with their reproductive activity and induce nestmates to respond by feeding them. Such frequent trophallaxis could supply their protein needs for oogenesis, constituting a social pathway to worker reproduction. However, some individuals can develop ovaries without producing queen pheromones. The consumption of protein-rich pollen could be an alternative solitary pathway for them to satisfy this dietary requirement. In order to investigate the way in which workers obtain proteins for oogenesis, we created orphaned worker groups and determined ovarian and pheromonal development in relation to pollen consumption of selected workers. Individuals that did not consume pollen had significantly more developed ovaries and produced significantly more queen mandibular pheromone than workers that fed directly on pollen. Our results suggest that workers producing queen-like secretions are fed trophallactically. However, reproductive workers that lacked queen pheromones had consumed little or no pollen, suggesting that they also obtained trophallaxis. Although pollen consumption might contribute to sustaining oogenesis, it does not appear to be sufficient. Trophallaxis as a means of obtaining proteins seems to be necessary to attain reproductive status in queenless honeybee colonies.

Absconding in honeybees ( Apis mellifera ) in relation to queen status and mode of worker reproduction

We investigated absconding frequency and latency in queenright and queenless honeybee colonies in thelytokous Apis mellifera capensis, arrhenotokous Apis mellifera scutellata and their natural thelytokous hybrids. There was no significant difference in frequency of absconding among any of the queenright colonies. Absconding was significantly greater in thelytokous queenless colonies than in the queenless arrhenotokous ones. Latency to absconding did not differ among the three groups of queenright colonies nor between the queenright and queenless colonies of A.m. capensis and A.m. scutellata. There were significant differences in latency between queenright and queenless hybrids and significant differences in latency among the three groups of queenless colonies. Among queenless colonies, A.m. capensis absconded twice as readily as did A. m. scutellata and the hybrids were intermediate. Afterabsconding events include the fates of the absconding colony as well as nestmates left behind. One group of orphaned nestmates of A. m. capensis amalgamated with another queenright colony. In the case of A. m. scutellata either drones were produced or the residual queenless colony was joined by a queenless thelytokous group, subsequently reared a queen and then absconded. Differences in the rate and degree of ovarial development indicate that queenless thelytokous workers have the physiological capacity for reproduction, a trait that contributes to colony fitness.

Reproductive competition in queenless honey bee colonies (Apis mellifera L.)

Previously we reported that there are subfamily differences in drone production in queenless honey bee colonies, but these biases are not always explained by subfamily differences in oviposition behavior. Here we determine whether these puzzling results are best explained by either inadequate sampling of the laying worker population or reproductive conflict among workers resulting in differential treatment of eggs and larvae. Using colonies composed of workers from electrophoretically distinct subfamilies, we collected samples of adult bees engaged in the following behavior: “true” egg laying, “false” egg laying, indeterminate egg laying, egg cannibalism, or nursing (contact with larvae). We also collected samples of drone brood at four different ages: 0 to 2.5-h-old eggs, 0 to 24-h-old eggs, 3 to 8-day-old larvae, and 9 to 14-day-old larvae and pupae. Allozyme analyses revealed significant subfamily differences in the likelihood of exhibiting egg laying, egg cannibalism, and nursing behavior, as well as significant subfamily differences in drone production. There were no subfamily differences among the different types of laying workers collected from each colony, suggesting that discrepancies between subfamily biases in egg-laying behavior and drone production are not due to inadequate sampling of the laying worker population. Subfamily biases in drone brood production within a colony changed significantly with brood age. Laying workers had significantly more developed ovaries than either egg cannibals or nurses, establishing a physiological correlate for the observed behavioral genetic differences. These results suggest there is reproductive conflict among subfamilies and individuals within queenless colonies of honey bees. The implications of these results for the evolution of reproductive conflict, in both queenright and queenless contexts, are discussed.

Reproductive competition in queenless honey bee colonies ( Apis mellifera L.)

Reproductive competition in queenless honey bee colonies ( Apis mellifera L.)

Intracolonial behavioral variation in worker oviposition, oophagy, and larval care in queenless honey bee colonies

Two experiments were performed to determine whether worker reproduction in queenless honey bee colonies is influenced by colony genetic structure. In Experiment 1, allozyme analyses of workers and worker-derived drone larvae revealed that in half the colonies, there were genotypic differences in worker egg-laying behavior (presumed to involve actual oviposition), but biases in drone production were not always consistent with biases in egg-laying behavior. In Experiment 2, allozyme analyses again revealed intracolonial differences in egg-laying behavior and in behavior patterns thought to involve oophagy and larval care. Data support the hypothesis of a genetic influence on this intracolonial behavioral variation. Differences in the genotypic distributions of worker-derived drones relative to workers engaged in oviposition behavior in queenless colonies may be a consequence of genetic variability for egg production or for treatment of eggs and larvae (possibly coupled with kin recognition), or both.

Effect of Various Dosages of Queen Mandibular Gland Pheromone on the Inhibition of Queen Rearing in the Honey Bee (Hymenoptera: Apidae)

The effects of various dosages of queen mandibular pheromone on the inhibition of queen rearing in queenless honey bee colonies was investigated. Dosages ranged from 10−3 to 10 queen equivalents (Qeq) per day; one Qeq was the amount of pheromone in an average pair of queen mandibular glands. Both temporal and dose-dependent effects were found. The higher doses were effective at preventing queen rearing early in the experiment (days 0–6), but by day 10, when queen rearing was effectively completed, there were few effects at any dose. Approximately 1 Qeq/d was sufficient to suppress queen rearing for up to 6 d in colonies of 8,000–10,000 workers. Results indicate that the active components of queens' mandibular glands exhibit dose-dependent effects on queen rearing, but there are additional requirements necessary for the suppression of queen rearing for periods longer than 6 d. The amount of pheromone secreted by queens and distributed by workers may be considerably greater than previously considered.

Laying-worker Production of Drones in Mixed Colonies of Africanized and European Honey Bees (Hymenoptera: Apidae)

Queenless honey-bee colonies ( Apis mellifera L.) with mixed populations of Africanized and European workers produced 15-fold more Africanized drones than European drones. Drones developed from eggs laid by previously nonreproductive workers. First eclosion of Africanized drones preceded that of European drones by 2.4 days. Laying workers of both bee types developed more rapidly when colonies had Africanized queens and brood before queenlessness than when colonies had European queens and brood. The percentage of European drones of the total number of drones that eclosed each day changed significantly in a curvilinear manner over 15 days, starting near 0, increasing to a high near 8, and then decreasing to near 0.