Queen Mandibular Gland Pheromone Research Articles

Genomic analysis of the interactions between social environment and social communication systems in honey bees (Apis mellifera)

Social context is often a primary regulator of social behavior, but genes that affect or are affected by social context have rarely been investigated. In social insects, caste specific pheromones are key modulators of social behavior, e.g., in honey bees the queen mandibular gland (MG) pheromone mediates reproductive dominance, its absence prompting ovary activation and queen pheromone production in workers. Here, we investigate the effect of social environment on genome-wide expression patterns in the MG, to determine how social context modulates expression of genes that, in turn alter social environment. We used microarrays to examine the MGs of virgin and mated queens, and queenright (QR) and queenless (QL) workers with or without activated ovaries. Approximately 2554 transcripts were significantly differentially expressed among these groups, with caste and social context being the main regulators of gene expression patterns, while physiological state (ovary activation) only minimally affecting gene expression. Thus, social context strongly regulates expression of genes, which, in turn, shape social environment. Among these, 25 genes that are putatively involved in caste selective production of the fatty-acid derived MG pheromone were differentially expressed in queens and workers. These genes whose functions correspond with enzymatic or transport processes emphasize the occurrence of disparate pheromone biosynthetic pathways for queens and workers, adding another dimension regarding the regulation of these important pheromones. Gene ontology analysis also revealed genes of different functional categories whose expression was impacted by caste or by the social environment, suggesting that the MG has broader functions than pheromone biosynthesis.

Anarchistic queen honey bees have normal queen mandibular pheromones

Anarchistic honey bees are a line developed by recurrent selection in which workers frequently lay eggs. In unselected colonies, workers refrain from reproduction in response to pheromonal signals that indicate the presence of brood and a queen. We show that queen type (anarchistic or wild type) has no effect on rates of ovary activation of anarchistic or wild type workers. In addition, we show that an important component of the queen’s signalling system, the queen mandibular gland pheromone, is similar in wild type and anarchistic queens. Anarchistic larvae do not inhibit worker ovary development to the same degree as wild type larvae, however all colonies in this experiment contained only wild type larvae. Anarchistic workers had greater rates of ovary activation than wild type workers in colonies headed by either queen type. We therefore conclude that there must be differences in the transmission or reception of queen pheromones, or worker sensitivity to these compounds. These results clearly demonstrate that anarchy is a complex syndrome, not simply the result of reduced pheromone production by anarchist queens and larvae.

Selection on worker honeybee responses to queen pheromone (Apis mellifera L.).

Disruptive selection for responsiveness to queen mandibular gland pheromone (QMP) in the retinue bioassay resulted in the production of high and low QMP responding strains of honeybees (Apis mellifera L.). Strains differed significantly in their retinue response to QMP after one generation of selection. By the third generation the high strain was on average at least nine times more responsive than the low strain. The strains showed seasonal phenotypic plasticity such that both strains were more responsive to the pheromone in the spring than in the fall. Directional selection for low seasonal variation indicated that phenotypic plasticity was an additional genetic component to retinue response to QMP. Selection for high and low retinue responsiveness to QMP was not an artifact of the synthetic blend because both strains were equally responsive or non-responsive to whole mandibular gland extracts compared with QMP. The use of these strains clearly pointed to an extra-mandibular source of retinue pheromones (Pankiw et al. 1995; Slessor et al. 1998; Keeling et al. 1999).

The Releaser Effects of the Tergal Gland Secretion of Queen Honeybees ( Apis mellifera )

Queen honeybees are attractive to their workers, due partially to the pheromonal bouquet they secrete. Queen mandibular gland pheromone is a powerful attractant to worker honeybees but it is not solely responsible for eliciting retinue behavior. The attractiveness of virgin queen tergal gland secretions and queen mandibular pheromone to worker honeybees was tested using a retinue bioassay. The number of workers attending the treated pseudoqueen lures was videorecorded in order to allow for the quantification of attractiveness. Queen mandibular gland secretions were more attractive than tergal gland secretions (P ≤ 0.008), and both queen tergal gland secretions (P ≤ 0.0002) and mandibular gland secretions (P ≤ 0.0001) were significantly more attractive than the control treatment. This laboratory bioassay indicates that queen tergal gland secretions have a releaser effect that evokes retinue behavior from worker honeybees.

Queen mandibular gland pheromone influences worker honey bee ( Apis mellifera L.) foraging ontogeny and juvenile hormone titers

Synthetic queen mandibular gland pheromone (QMP) was applied to honey bee colonies to test two hypotheses: (i) QMP acts like a primer pheromone in the regulation of age-related division of labor, and (ii) this primer effect, if present, varies in three strains of workers that show genetically-based differences in their retinue attraction response to QMP (a pheromone releaser effect). Strains of workers that were high, or low in their response to QMP in a laboratory bioassay, as well as unselected `wild-type' workers, were fostered in queenright colonies with or without supplemental QMP. Effects of QMP on foraging ontogeny and juvenile hormone III (JH) blood titers in worker honey bees were measured. Bees in QMP-supplemented colonies showed significant delays in foraging ontogeny, and foraging activity was reduced. They also had significantly lower JH titers, although the titer curves were somewhat atypical. There were no differences in foraging ontogeny or JH titers among the three strains. We conclude that (i) QMP can delay the ontogeny of foraging by some mechanism that suppresses JH production, (ii) this QMP primer response is independent of the retinue releaser response, and (iii) QMP can play an important role in regulating division of labour.

Balling behaviour in the honey bee in response to exogenous queen mandibular gland pheromone

SUMMARYHoney bee (Apis mellifera) colonies generally respond to the introduction of a foreign queen by aggressively surrounding or ‘balling’ the new queen. We explored the role of queen mandibular gland pheromone (QMP) in initiating balling behaviour. The addition of a synthetic blend of QMP to the abdomen of worker bees initiated balling behaviour of these workers when re-introduced into their own colony. There was a positive, dose-dependent relationship between the number of balls formed, time to ball formation and size of balls formed. When the QMP dose was below that normally found on a queen, 10−3 queen equivalents, it resulted in significantly slower ball formation and smaller ball diameter. The acid components of the five-component QMP elicited balling behaviour while the aromatic components did not, but the full blend elicited the strongest response. Stinging behaviour was the most prevalent and persistent factor preceding the formation of balls. We concur with others who have proposed that a ‘marking’ pheromone is released when an aggressive worker flexes her abdomen, and that the release of this pheromone causes ball formation. There were no obvious changes in resident queen behaviour while balling of QMP-treated workers was occurring. We conclude that queen mandibular gland pheromone is a significant signal in foreign queen recognition and the initiation of balling behaviour.

Queen rearing suppression in the honey bee - evidence for a fecundity signal

Previous studies have shown that a pheromone produced in the honey bee (Apis mellifera L.) queen's mandibular glands suppresses the rearing of new queens. The present studies investigated the existence of an as-yet unidentified, brood-associated signal that acts in conjunction with the queen's mandibular pheromone to suppress queen rearing. When we manipulated the levels of synthetic queen mandibular gland pheromone (QMP) and young brood in queenless colonies, there was a 50 % reduction in the number of queen cells reared compared to colonies receiving QMP alone. In a second experiment, colonies containing eggs and young larvae but no QMP reared on average only one queen cell after 24 h, while colonies containing older larvae reared four queen cells, suggesting that combs with younger brood were the source of the second signal. In a third experiment, we attempted to induce queen rearing in the presence of the queen by removing eggs and young larvae in colonies with healthy queens. Six of nine brood-manipulated colonies initiated queen cells, compared with only one of nine colonies receiving a sham manipulation. The results from this experiment suggest that a decline in the brood signal initiated queen supersedure in honey bee colonies. Results from all three experiments clearly demonstrate the existence of a "fecundity" signal that acts with QMP to suppress queen rearing.

Mandibular gland components of european and africanized honey bee queens (Apis mellifera L.)

The composition of the five-component honey bee queen mandibular gland pheromone (QMP) of mated European honey bee queens was compared to those of virgin and drone-laying (i.e., laying only haploid unfertilized eggs that develop into males), European queens and Africanized mated queens. QMP of mated European queens showed significantly greater quantities of individual components than all queen types compared, except for a significantly greater quantity of 9-hydroxy-(E)-2-decenoic acid (9-HDA) found in Africanized queens. Glands of European drone-laying queens contained quantities intermediate between virgin and mated queens, reflecting their intermediate reproductive state and age. QMP ontogeny shifts from a high proportion of 9-keto-(E)-2-decenoic acid (ODA) in young unmated queens to roughly equal proportions of ODA and 9-HDA in mated queens. A biosynthetic shift occurs after mating that results in a greater proportion of 9-HDA, methylp-hydroxybenzoate (HOB), and 4-hydroxy-3-methoxyphenylethanol (HVA) production, accompanied by a decreased proportion of ODA. Africanized QMP proportions of ODA and 9-HDA were significantly different from European queens. A quantitative definition of a "queen equivalent" of QMP is proposed for the various queen types, and a standard queen equivalent for mated European honeybee queen mandibular gland pheromone is adopted as 200µg ODA, 80µg 9-HDA, 20µg HOB, and 2 µg HVA.

Queen attendance behavior of worker honey bees (Apis mellifera L.) that are high and low responding to queen mandibular pheromone

Queen attendance behavior of workers from selected honey bee colonies with high and low worker retinue response to synthetic queen mandibular gland pheromone (QMP) was investigated. Antennating, licking, grooming, and feeding of the queen by workers from high and low responding colonies were examined. High and low QMP responding workers did not attend the queen differently. However, workers originating from different colonies antennated and licked the queen more frequently than others, suggesting there may be a genetic basis for queen attendance behavior not necessarily associated with response to QMP. The median age of queen attendance was independent of strain.

Behavior of Queen and Worker Honey Bees (Hymenoptera: Apidae) in Response to Exogenous Queen Mandibular Gland Pheromone

When a honey bee colony loses its queen the primary queen signal, queen mandibular gland pheromone declines, which initiates immediate and well documented changes in worker behavior. However, little is known regarding behavioral changes that might occur if queen pheromone levels are increased. To investigate possible positive or negative, or both, feedback from exogenous queen mandibular gland pheromone, glass-walled honey bee colonies were treated with various doses of synthetic queen pheromone and worker and queen behaviors monitored over a 3-d period. There were no differences in queen behavior with the addition of queen pheromone. Worker behavior was altered slightly at higher doses, with colonies receiving the highest pheromone dose having significantly more nectar foragers and higher activity levels on day 3. Additionally, some workers that removed pheromone from the glass slides were attacked (balled) by other workers. Balling was positively correlated with increasing dose, and occurred seasonally in the spring and fall but not the summer. Although decreasing levels of queen pheromone cause rapid behavioral changes, surprisingly, we observed only slight changes in worker behavior and no changes in queen behavior with the addition of large doses of queen pheromone. Thus, we found no evidence of queen mandibular gland pheromone feedback to the queen.

Suppression of queen rearing in European and Africanized honey beesApis mellifera L. by synthetic queen mandibular gland pheromone

Queen rearing is suppressed in honey bees (Apis mellifera L.) by pheromones, particularly the queen's mandibular gland pheromone. In this study we compared this pheromonally-based inhibition between temperate and tropically-evolved honey bees. Colonies of European and Africanized bees were exposed to synthetic queen mandibular gland pheromone (QMP) for ten days following removal of resident queens, and their queen rearing responses were examined. Queen rearing was suppressed similarly in both European and Africanized honey bees with the addition of synthetic QMP, indicating that QMP acts on workers of both races in a comparable fashion. QMP completely suppressed queen cell production for two days, but by day six, cells containing queen larvae were present in all treated colonies, indicating that other signals play a role in the suppression of queen rearing. In queenless control colonies not treated with QMP, Africanized bees reared 30% fewer queens than Europeans, possibly due to racial differences in response to feedback from developing queens and/or their cells. Queen development rate was faster in Africanized colonies, or they selected older larvae to initiate cells, as only 1 % of queen cells were unsealed after 10 days compared with 12% unsealed cells in European colonies.

Mechanisms by Which Honey Bee (Hymenoptera: Apidae) Queen Pheromone Sprays Enhance Pollination

Honey bee queen mandibular gland pheromone, when sprayed on blooming crops, can enhance pollination and subsequent crop yields. We investigated two mechanisms by which queen pheromone might enhance pollination. First, we observed foragers on pheromone-sprayed and control plots in highbush blueberry and cranberry to detect possible pheromone-induced modifications of bee behavior. Foragers behaved similarly on individual flowers, but stayed significantly longer and visited more flowers in pheromone-sprayed plots. Second, we examined the recruitment response to paired pheromone- versus control-sprayed artificial feeders in conjunction with behavioral observations of foragers returning to the colony, and explored the relationship between pheromone dose and recruitment. Recruitment to artificial feeders sprayed with a low dose of pheromone was greater than to control feeders. Foragers from those pheromone-sprayed feeders spent significantly less time before and during unloading upon returning to the colony. A higher dose of pheromone was not different from either the control or low dose in eliciting both recruitment and the associated in-hive behaviors. We conclude that a combination of increased recruitment to queen mandibular gland pheromone-sprayed plots and greater time spent by foragers with increased flower visitation contribute to enhanced pollination of blooming crops treated with queen mandibular gland pheromone.

Variation in worker response to honey bee (Apis mellifera L.) queen mandibular pheromone (Hymenoptera: Apidae)

Genetic and environmental influences on the worker honey bee retinue response to queen mandibular gland pheromone (QMP) were investigated. Worker progeny were reared from queens originating from four sources: Australia, New Zealand, and two locations in British Columbia, Canada (Simon Fraser University and Vancouver Island). Progeny from New Zealand queens responded significantly higher (P < 0.05) than progeny from Australia in a QMP retinue bioassay. Retinue response was not related to queen production of pheromone or colony environment, and the strain-dependent differences in retinue bioassay responses were maintained over a wide range of dosages. Selected high- and low-responding colonies were bioassayed over the course of 1 year. High-responding colonies contacted QMP lures more frequently than low-responding colonies (P < 0.05) throughout the year except in late summer. We conclude that there is a strong genetic component to QMP response by worker honey bees, as well as a seasonal effect on response.

Movement of honey bee (Apis mellifera L.) queen mandibular gland pheromone in populous and unpopulous colonies

The mode of intranest transfer of the honey bee queen mandibular gland pheromone complex (QMP) was investigated in unpopulous and populous, slightly congested colonies, using synthetic QMP containing tritiated 9-keto-2(E)-decenoic acid, one of the QMP components. Radiolabel was rapidly transported from the center to the peripheral regions of the nest, and in a manner consistent with worker to worker transport. Population size and congestion had no effect on the relative rates of movement from the center to the periphery of the nest or on the mean amounts of radiolabel on individual bees. However, a significantly smaller proportion of the workers in the populous colonies received detectable amounts of radiolabel than in the uncongested colonies, and workers carrying especially large amounts of radiolabel were less numerous in the crowded colonies. It is suggested that, at the stage of colony development that the colonies were in, population size has more of an effect on intranest pheromone transmission than does crowding. Interference with pheromone transfer may occur only at higher levels of congestion than were created, and nearer to the reproductive phase of colony development. An alternative hypothesis is that colony crowding does not significantly affect QMP transport and that the onset of reproductive queen rearing may be associated more with changes in worker thresholds of response to QMP.

INTRA-NEST TRANSMISSION OF AROMATIC HONEY BEE QUEEN MANDIBULAR GLAND PHEROMONE COMPONENTS: MOVEMENT AS A UNIT

AbstractThe intra-nest transmission of two aromatic components of honey bee queen mandibular gland pheromone, 4-hydroxy-3-hydroxyphenylethanol (HVA) and methyl p-hydroxybenzoate (HOB), is quantitatively described. After being secreted onto the body surface of the queen, the greatest quantities of HVA and HOB are removed by workers in the queen’s retinue, especially those contacting the queen with their mouthparts. Other workers acquire pheromone components via direct contact with retinue bees or with other workers that have already acquired queen pheromone. HVA and HOB can also reach workers through queen or worker "footprints," although the relatively little material deposited onto the comb wax becomes less available with time, presumably because of diffusion into the wax. Pheromone material is removed from circulation by being internalized into workers, the queen, and the wax. Rates of HVA and HOB transfer between different entities within the nest are described in terms of pseudo first-order rate constants. The intra-nest transfer of these two components, both qualitatively and quantitatively, is similar to that described earlier for the most abundant queen mandibular gland pheromone component, 9-keto-2-(E)-decenoic acid (9-ODA; Naumann et al. 1991). Thus, the queen mandibular gland pheromone complex is transferred through the nest as a unit rather than as individual components moving at different rates.

Grooming behaviors and the translocation of queen mandibular gland pheromone on worker honey bees (Apis mellifera L)

Summary — Self-grooming resulted in the translocation of synthetic queen mandibular gland pheromone from the mouthparts and head to the abdomen of honey bee workers. The several observed grooming behaviors do not appear to function solely for pheromone translocation. Little if any, pheromone moved passively on the cuticle. This study provides evidence for an active mechanism of pheromone movement on individual social insects, and suggests that these behaviors play a significant role in the queen’s communication with her workers.

Effects of Synthetic, Honey Bee (Hymenoptera: Apidae) Queen Mandibular-Gland Pheromone on Workers in Packages

Packages of worker honey bees, Apis mellifera L., were provided with either queens, one of two doses of synthetic queen mandibular-gland pheromone, or a blank lure, and treated as commercially produced packages. There were no significant differences between queenright and pheromone-treated packages in worker agitation, cluster density, sound production, worker mortality, or colony population 3 wk after hiving. Packages in the blank treatments usually showed statistically significant or qualitative differences from the other three treatments. Queen introduction problems were found with all queenless treatments. Synthetic queen mandibular-gland pheromone can be used as a queen substitute for the shipment and temporary storage of packaged bees, provided that proper care is taken when introducing queens following package shipment.

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.

Synthetic pheromones to attract honeybee (Apis mellifera) swarms

SummaryLures containing the synthetic pheromone components (E)- and (Z)-citrals, geraniol and nerolic and geranic acids made new hives, not previously occupied by honeybee colonies, more attractive to caged honeybee swarms than unbaited hives (20 out of 20 tests). The lure also made old hives, previously occupied by colonies, more attractive to caged swarms (19 out of 20 tests) and to swarms in natural conditions (12 occupied compared with none without the lure). Adding (E)-9-oxo-2-decenoic acid (part of the queen's mandibular gland pheromone) to the lure increased its attractiveness to caged swarms (20 out of 20 tests). Practical implications in beekeeping are discussed.