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Pheromonal control by the honey bee queen is achieved through the use of secretions from diverse glandular sources, but the use of pheromones from a variety of glandular sources by reproductively dominant workers, has not previously been explored. Using the social parasite, Apis mellifera capensis clonal worker we studied the diversity of glandular sources used for pheromonal control of reproductively subordinate A. m. scutellata workers. To determine whether pheromones from different glandular sources are used by reproductively active workers to achieve dominance and evaluate the degree of pheromonal competition between workers of the two sub-species, we housed groups of workers of the two sub-species together in cages and analysed mandibular and tergal gland secretions as well as, ovarian activation status of each worker after 21 days. The results showed that A. m. capensis invasive clones used both mandibular and tergal gland secretions to achieve reproductive dominance and suppress ovarian activation in their A. m. scutellata host workers. The reproductively dominant workers (false queens) produced more queen-like pheromones and inhibited ovarian activation in subordinate A. m. scutellata workers. These results show that tergal gland pheromones working in synergy with pheromones from other glands allow individual workers (false queens) to establish reproductive dominance within these social groups and to act in a manner similar to that of queens. Thus suggesting that, the evolution of reproductively dominant individuals (queens or false queens) and subordinate individuals (workers) in social insects like the honey bee is the result of a complex interplay of pheromonal signals from different exocrine glands. [ABSTRACT FROM AUTHOR]

In honey bee colonies, workers, in particular of 'anarchistic' lineages, can activate their ovaries and lay eggs, even in the presence of the queen. We identified three queenright colonies showing typical signs of worker reproduction. To characterize this new lineage, we extracted the mandibular gland and analyzed it using gas chromatography. The total amounts of the five main components of the mandibular gland, namely methyl p-hydroxyben-zoate (HOB), 9-oxo-2(E)-decenoic acid (9-ODA), (S)-9-hydroxy-(E)-2-decenoic acid (9-HDA), 10-HDA, and 10-hydroxyde-canoic acid (10-HDAA) were significantly higher in the mandibular gland profiles of workers with activated ovaries (AWs, 8.88 ± 1.71 μg) compared to workers with inactivated ovaries (IAWs, 4.00 ± 2.09 μg). Furthermore, the chemical profiles of IAWs were dominated by the 'worker substances' 10-HDA (34.64 ± 8.19 %) and its precursor 10-HDAA (22.88 ± 4.95 %), while the chemical profiles in AWs were dominated by the precursor of the queen substance 9-HDA (40.04 ± 7.55 %). The ratios of two precursor substances 10-HDAA/9-HDA of IAWs were more worker like (>1.0) whereas AWs were more queen like (≤1.0). These results suggest that the mandibular pheromones of anarchistic workers resemble a more queen-like reproductive active profile and that these workers may represent a reversion to a more basal reproductive phenotype. [ABSTRACT FROM AUTHOR]

In many species of social Hymenoptera, unmated workers can lay eggs that will produce males by parthenogenesis. Nevertheless, in queenright honey bee colonies (Apis mellifera), worker reproduction is low. One possible mechanism for this difference is worker policing, the removal of worker-laid eggs by other workers. This behavior can evolve in species in which queens are multiply mated, where workers are more closely related to the sons of their mother than those of their sisters. Another possible mechanism of the low level of worker reproduction is worker-laid eggs being less viable than queen-laid eggs. We show that this difference in quality is the case for honey bees. [ABSTRACT FROM AUTHOR]

The honeybee queen’s mandibular gland pheromones (QMP) are essential for the suppression of worker reproduction. Worker ovary activation is regulated by alternative splicing of a CP2-transcription factor named gemini. Since workers with activated ovaries also produce QMP in their mandibular glands, we tested whether alternative splicing of gemini also controls mandibular gland pheromone biosynthesis in workers using RNA interference. Altering the splice pattern of gemini resulted in enhanced levels of the queen-specific components of the mandibular gland pheromone in queenless honeybee workers, suggesting that gemini functions as a pleiotropic regulatory switch influencing both ovary activation and resulting in QMP synthesis in workers. Because the QMP produced by these workers suppresses ovary activation in other workers, gemini seems to be a key regulatory gene affecting reproductive hierarchies among workers in queenless colonies. [ABSTRACT FROM AUTHOR]

When a honeybee colony loses its queen, workers activate their ovaries and begin to lay eggs. This is accompanied by a shift in their pheromonal bouquet, which becomes more queen like. Workers of the Asian hive bee Apis cerana show unusually high levels of ovary activation and this can be interpreted as evidence for a recent evolutionary arms race between queens and workers over worker reproduction in this species. To further explore this, we compared the rate of pheromonal bouquet change between two honeybee sister species of Apis cerana and Apis mellifera under queenright and queenless conditions . We show that in both species, the pheromonal components HOB, 9-ODA, HVA, 9-HDA, 10-HDAA and 10-HDA have significantly higher amounts in laying workers than in non-laying workers. In the queenright colonies of A. mellifera and A. cerana, the ratios (9-ODA)/(9-ODA + 9-HDA + 10-HDAA + 10-HDA) are not significantly different between the two species, but in queenless A. cerana colonies the ratio is significant higher than in A. mellifera, suggesting that in A. cerana, the workers' pheromonal bouquet is dominated by the queen compound, 9-ODA . The amount of 9-ODA in laying A. cerana workers increased by over 585% compared with the non-laying workers, that is 6.75 times higher than in A. mellifera where laying workers only had 86% more 9-ODA compared with non-laying workers. [ABSTRACT FROM AUTHOR]

In honeybees, worker reproduction is mainly regulated by pheromones produced by the brood and the queen. The source of one of the queen pheromones influencing worker reproduction has been located in the mandibular glands. In nonlaying workers, this gland’s profile is dominated by fatty acids that are incorporated into the food given to the brood and to nest mates. After queen loss and onset of reproductive activity, workers are able to synthesize different fatty acids, which are normally only produced by queens and that contribute to their reproductive success. Apis mellifera capensis workers have the ability to rapidly produce queen-like mandibular profiles that could represent an important factor in their ability to behave as facultative intraspecific social parasites. Indeed, A. m. capensis workers can take over reproduction from the host queens in colonies of other subspecies. Here, we show that in the presence of their own queen, the mandibular gland profile of A. m. capensis workers is dominated by the precursor of the major compound of the queen pheromone. This is a unique trait among honeybee workers and suggests that A. m. capensis workers are primed for reproduction and that this phenomenon represents a pheromonal predisposition to social parasitism. We identified geographical variation in the ratio of queen- to worker-specific compounds in the mandibular gland profile of A. m. capensis workers, which corresponds with the introgression with the neighboring subspecies A. m. scutellata. [ABSTRACT FROM PUBLISHER]

To explore reasons for the unusually high rates of worker ovary activation in Apis cerana, we investigated the reproductive physiology of workers in conspecific and mixed-species colonies of A. cerana and its sibling species Apis mellifera under queenright and queenless conditions. In both queenless and queenright conspecific colonies, the proportion of A. cerana workers with activated ovaries was significantly greater than the proportion of A. mellifera workers with activated ovaries. Apis cerana workers showed significantly greater ovary activation in queenright mixed-species colonies than in conspecific queenright colonies. Moreover, there was significantly greater ovary activation in A. cerana workers in mixed-species colonies headed by A. mellifera queens than A. mellifera workers in mixed-species colonies headed by A. cerana queens. Apis mellifera workers in conspecific queenless colonies showed significantly greater ovary activation than those in mixed-species queenless colonies. Quantification of the chemical components of mandibular gland pheromones of queens of the 2 species showed that they are similar. Combined, our results show that queen signals have been preserved between the 2 species and that workers respond to the heterospecific signals from queens. However, despite the similarity in the queen mandibular gland fatty acid secretions between the 2 species, workers respond differentially toward hetero- and conspecific queens. [ABSTRACT FROM PUBLISHER]