Queen Bee Chemistry

It is so easy to jump to conclusions when observing and studying honeybees. To the uninitiated, the female workers seem to be the key to the hive. After all, they do so much. They start off early in their lives cleaning the nest. A few days later they are feeding larvae, then secreting wax to build the honeycomb. At about the age of 20 days, they act as guards to the entrance of the nest, and when their glands degenerate, they’re off collecting pollen and nectar for the rest of their lives. After a successful trip, they perform elaborate symbolic dances, revealing both the angular and scalar components of their displacement from flowers to hive. In contrast, the males and the queen bee don’t do any of the above.

But the female workers, as industrious as they may be, do not reproduce and do not exert the strongest influence in the hive. The failure of a single and other type of individual is consistently listed as a cause of honeybee colony mortality.  That individual is the queen bee. She is born in a cell built larger than the others to accommodate her bigger size. But what makes her develop into a queen? After observing that the queen bee larva and adult queen is only fed a so-called royal jelly, a white mixture of protein and sugar secreted from the heads of worker bees, it was long assumed that the mixture held the secret. But a few years ago it was revealed that the key was not necessarily contained in the royal jelly but in what the queen bee was not fed: pollen and nectar. The latter food- source for other larvae contains flavonoids, some of which include inhibitors. Investigators reared larvae in the lab on a royal jelly diet adulterated with para coumaric acid, and by the time they developed into adults, ovary development had been stunted.

queencourt
A queen bee courted by other females. Notice her  larger size and the yellow marker added by a biologist. http://articles.extension.org/pages/73133/honey-bee-queens:-evaluating-the-most-important-colony-member

When not exposed to such gene-silencers, a queen bee will normally emerge from her larval stage five days sooner than other bees. After killing competing virgin queens, she diversifies genetic input by mating with 7 to 17 drones, who die soon afterwards. With the ability to store about seven million sperm, the queen will then be fed and groomed by workers while she lays eggs for the rest of her life. In what surely is a matriarch’s fantasy, the older a queen bee gets, the more prolific she becomes in laying eggs, becoming even more attractive to her servants. But how does this happen?

JBFree_source-Pheromones
The various effects on bee behavior controlled by a complex of a chemical signals from the queen bee. Source: JB Free

It has been known for decades that a pheromone (chemical messenger) is released from the queen bee’s mandibular gland in her lower mouth.  In subsequent experiments, however, the compound that had been identified as E-9-oxodec-2-enoic acid, could not on its own exert any retinue behaviour on worker bees. Retinue behaviour is what’s used to described the way workers groom and feed the queen. It’s only part of the influence that the queen bee’s chemical messengers can have on bee behaviour, as revealed in the adjacent illustration. There are a series of effects with immediate impacts (releaser) and those with long term consequences(primer) on the endocrine and reproductive systems of workers.

beehormones
Three of at least 9 compounds released to make sure the queen bee gets groomed and fed by other females.

Eventually, in the late 1980s Canadian researchers from Simon Fraser University revealed that the original compound was really a mixture of two mirror-image molecules known as enantiomers. They also identified three other compounds from the mandibular gland. When a tube containing the 5-compound mixture was placed in a beehive, the workers left the cells that they were building for new queens and started to press their antennae against the glass while licking the synthetic queen. But the mystery wasn’t entirely solved. As the authors of the same study stated in a review paper 16 years later, the 5-compound mixture is ineffective in some strains of honeybees. The response is influenced by variable genetic factors and by at least 4 other compounds, specifically coniferyl alcohol, another alcohol, methyl oleate and linolenic acid. As the queen ages she releases higher concentrations of the compounds to ensure a positive correlation between the attention she receives and the amount of eggs she lays.

When looking beyond the queen and to the general health of bees, including solitary ones, it was assumed that the concentration of pesticides found in bees was too low to harm them. If inspected individually, each pesticide’s level is indeed below the bee’s threshold. But collectively, along with bee diseases and diminishing flower diversity, pesticides have a detrimental impact on a highly beneficial insect. Whether or not bees produce honey and wax for us, they are the sole and essential pollinators of plants such as squash, zucchini, pumpkins, kiwi, watermelon, cantaloupes and Brazil and macadamian nuts. Besides, their mysteries have justifiably inspired more research than any other insect.

Sources:

  • Honey Bee Queens: Evaluating the Most Important Colony Member
    Bee Health October 07, 2015  Philip A. Moore, Michael E. Wilson, John A. Skinner
    Department of Entomology and Plant Pathology, The University of Tennessee, Knoxville
  •  A dietary phytochemical alters caste-associated gene expression in honey bees. Wenfu Mao, Mary A. Schuler, and May R. Berenbaum. 2015. Science Advances 1(7).

  • Pheromone Communication in the Honeybee (Apis mellifera L.) KEITH N. SLESSOR,1 MARK L. WINSTON,2 and YVES LE CONTE3 Journal of Chemical Ecology, Vol. 31, No. 11, November 2005 (#2005) DOI: 10.1007/s10886-005-7623-9
  • New components of the honey bee (Apis mellifera L.)
    queen retinue pheromone. Christopher I. Keeling*†, Keith N. Slessor*, Heather A. Higo‡, and Mark L. Winston‡ Proc Natl Acad Sci U S A. 2003 Apr 15;100(8):4486-91. Epub 2003 Apr 3.
Advertisements

One thought on “Queen Bee Chemistry

Add yours

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

WordPress.com.

Up ↑

%d bloggers like this: