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The Royal Canadian Mint’s “Animal Architects” Coin Series Celebrates Insects and the ESC!

By Rebecca Hallett, ESC First Vice-President

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A year ago, an exciting new collaboration was initiated between the ESC and the Royal Canadian Mint. This collaboration grew from a letter sent by then President, Michel Cusson, and myself as chair of the Scientific Policy and Education committee, to the Mint commending them for the inclusion of insects on Canadian coins and offering the services of the ESC as a resource for the development of future insect coins. The response from the Mint was very warm and they immediately invited the ESC to be involved in the Animal Architects coin series.

Bee-coin

The Animal Architects coin series celebrates the “exceptional architects of Canada’s animal world and their unique constructions”. I was thrilled to see that the first coin in this new series has recently been released, depicting an iconic insect architect, the honeybee, with its hive.

View the sale sheet here for the 2012 $3 FINE SILVER COIN – ANIMAL ARCHITECTS: BEE & HIVE

The Mint also decided to recognize the involvement of the ESC in this series and, in 2013, to commemorate the Sesquicentennial of the ESC on the certificates of authenticity that accompany the coins.

The Bee & Hive coin has proven to be extremely popular and is selling rapidly.  The depiction of insects on coins helps to increase appreciation for nature in general, and insects in particular, among the Canadian and coin-collecting public. I hope you will consider supporting this endeavour by treating yourself or a loved one to one or all of the coins in this series.

Coins can be ordered from the Royal Mint website:

http://www.mint.ca/store/coin/14-oz-fine-silver-coin-animal-architects-bee–hive-2013-prod1670011

Or obtained through one of the Mint’s dealers:

http://www.mint.ca/store/mint/customer-service/dealer-locator-1400026

I’ve got my Bee & Hive coin reserved and am rushing off to Toronto tomorrow to collect it!

Keep your eyes open in the fall for the next Animal Architects coin to emerge…

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Physiology Fridays: From boozy breath to colony control: ethyl oleate production in honeybees

Honey bee flying with pollen - Photo by Alex Wild

Honey bee flying with pollen – Photo by Alex Wild, used with permission

Honeybee colonies are famous for their orderly divisions of labour.  As worker bees grow up, they transition from housekeepers (cleaning the colony) to nurse bees (feeding young bees), to finally switching to foragers who go out and collect nectar and pollen for the rest of the colony.   To maintain a healthy colony, bees need to decide how many foragers and how many nurse bees are needed, and control of these numbers is accomplished by pheromone levels within the colony.

In honeybee colonies, there are pheromones like the alarm pheromone that cause immediate behavioural responses (called releaser pheromones) and others that trigger physiological changes like hormones do (called primer pheromone).  From previous work, it seemed that ethyl oleate functions as a primer pheromone, produced by foragers, that delays the maturation of nurse bees into foragers.

“Ethyl oleate does not elicit any noticeable behavourial responses in recipient workers,” says Dr. Erika Plettner, who supervised a recent study on the synthesis of ethyl oleate at Simon Fraser University in British Columbia.  “Yet it has a profound physiological effect”.

To understand how this chemical is produced in the individual bee and then distributed in the colony, Carlos Castillo and colleagues from Simon Fraser University in British Columbia and the Laboratoire Biologie et protection de L’Abeillie in France looked at several ways to identify the source and synthesis of ethyl oleate.  This chemical can be produced by a reaction between oleic acid (a common fatty acid in insects) and ethanol.  While you might not think of honeybees as heavy drinkers, it turns out that yeasts in flower nectar ferment the sugars present into ethanol, and so the forager bees have much higher exposure to ethanol than nurse bees.

To figure out if ethanol and oleic acid can be made into ethyl oleate by honeybees, the researchers incubated different honeybee body parts from forager and nurse bees with these precursors.  They found highest production of ethyl oleate in the head tissues, and that both nurses and foragers could produce ethyl oleate when given ethanol.  In addition, in whole bees, they found that the ethyl oleate migrated from the gut to the exoskeleton of the bees where it would exude into the colony.

Taken together, these results suggest that making ethyl oleate, while it is useful for colony control, might also be a way to deal with the occupational hazard of consuming toxic ethanol.  “Foragers have much higher occupational exposure to ethanol than nurses do,” says Dr. Plettner.  “This is why they make ethyl oleate in nature”.

Ethyl oleate molecule

Ethyl oleate

To track down where exactly the ethyl oleate was synthesized, they coupled oleic acid to a chemical that would produce fluorescence when the oleic acid was combined with ethanol to produce ethyl oleate.  Under the microscope, areas that fluoresced showed where ethyl oleate was being made.  They found that ethyl oleate was made in the esophagus, honey crop and stomach.

The authors were also able to identify the genes responsible for the synthesis of ethyl oleate in the honeybee and the resulting enzymes that catalyze the reaction between oleic acid and ethanol.  These enzymes are then secreted into the gut fluid, where they produce ethyl oleate, which is then transported to the cuticle.

The biosynthesis of ethyl oleate then can be thought of a way of providing updates to the colony about the availability of flower nectar in nature.  “EO might be some kind of ‘resource meter’ that tells the nurses in the colony how many nectar and pollen resources are coming in,” says Dr. Plettner.  “If lots of food is coming in, then it makes sense to inhibit nurse to forager transition, as the nurses would be more needed in the brood chamber than as foragers.  Conversely, if few resources and/or foragers are coming in, then it makes sense to speed up development of nurses so that they can forage and fill the need.”

Castillo, C., Chen, H., Graves, C., Maisonnasse, A., Le Conte, Y. & Plettner, E. (2012). Biosynthesis of ethyl oleate, a primer pheromone, in the honey bee (Apis mellifera L.), Insect Biochemistry and Molecular Biology, 42 (6) 416. DOI: 10.1016/j.ibmb.2012.02.002

Corresponding author: Erika Plettner (plettner@sfu.ca)

Further reading:

Castillo, C., Maisonnasse, A., Conte, Y.L. & Plettner, E. (2012). Seasonal variation in the titers and biosynthesis of the primer pheromone ethyl oleate in honey bees, Journal of Insect Physiology, 58 (8) 1121. DOI: 10.1016/j.jinsphys.2012.05.010