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”.
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
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
http://esc-sec.ca/wp/wp-content/uploads/2017/01/ESC_logo-300x352.png00kbuggirlmarshallhttp://esc-sec.ca/wp/wp-content/uploads/2017/01/ESC_logo-300x352.pngkbuggirlmarshall2012-07-27 06:00:412019-11-14 20:21:51Physiology Fridays: From boozy breath to colony control: ethyl oleate production in honeybees
By Adam Jewiss-Gaines, a research assistant at Brock University.
When people ask me what the heck a calliphorid is (often after I have mentioned the family name and am being gawked at as if I’m crazy), I usually remark “You know those shiny flies you often see flying around in the spring and summer?” This isn’t technically 100% accurate since the genus Pollenia, one of the most commonly encountered genera of the family, is in fact non-reflective and grey. Upon closer inspection, a keen eye can also observe varying amounts of wrinkled, yellow hairs on the thorax. These two qualities distinguish Pollenia from other blow flies throughout North America. Despite being a little dull when compared to their more eye-catching iridescent relatives, Pollenia are ecologically important insects as they aid in plant pollination and the processing of various biomaterials.
Pollenia often become particularly active during the spring and summer months once the temperature warms up, although they can occasionally be spotted indoors in the wintertime on a warmer day. With a sudden onslaught of large, grey insects flying around when the snow begins to melt, it comes as no surprise that people tend to get irritated with them and consider them pests. Oftentimes they are mistaken as houseflies (Family Muscidae) causing Pollenia species to be labeled as potential food contaminators, but this is not the case. These insects are also particularly well-known for their clustering behaviour on walls, earning them their common name: cluster flies.
Even though Pollenia are extremely common, their general biology is largely unknown with a few exceptional details. It is known that larval Pollenia are parasites on various other organisms, such as maggots and worms. For example, Rognes (1991) noted that Pollenia pediculata, one of the most common species found throughout the continent, is a parasite of the earthworm species Eisenia rosea. Aside from this little tidbit however, specific information regarding the life cycles of Pollenia species is relatively scarce and further studies in this particular field would greatly improve our knowledge of the genus.
Until very recently it has been thought that all Pollenia found in North America were the same species (Polleniarudis), but after examining various collections throughout the world, Knut Rognes found that six members of the genus occur throughout the region. Terry Whitworth adapted much of Rognes’ work shortly thereafter into a nice, clean, simple identification key for North America. With accurate images and photography, however, characters could be even easier to distinguish and observe when one is able to compare a photograph to the creature they have under their microscope.
Therefore, to further expand on Terry’s key and clarify important visual characters, I collaborated with him and Dr. Steve Marshall to create a fully-illustrated digital key for distinguishing the six North American Pollenia species from one another. Now published in the Canadian Journal of Arthropod Identification, Cluster Flies of North America couples high-resolution images of important traits with a clean and simple interface to create a handy tool to be used by entomologists and non-entomologists alike. If you are relying on this key for identification, it is recommended to use physical specimens of Pollenia rather than images or photos, since even the best of hand-photographs have difficulty capturing key features. In addition, distribution maps are provided for each species, constructed from locality data of specimens from the University of Guelph Insect Collection and Terry Whitworth’s personal collection of Pollenia.
Creating this key has been a great opportunity, and I hope the entomological community is able to make good use of it. My sincere thanks go out to Steve Marshall, Terry Whitworth, the editors, and my labmates and friends for all of their support.
Jewiss-Gaines, A., Marshall, S.A. & Whitworth, T.L. (2012). Cluster flies (Calliphoridae: Polleniinae: Pollenia) of North America, Canadian Journal of Arthropod Identification, 19 DOI: 10.3752/cjai.2012.19
Rognes, K. 1991. Blowflies (Diptera, Calliphoridae) of Fennoscandia and Denmark. Fauna Entomologica Scandinavica Vol. 24.
https://esc-sec.ca/wp-content/uploads/2012/07/griseotomentosa-lateral-habitus-cropped.jpg500500Morgan Jacksonhttp://esc-sec.ca/wp/wp-content/uploads/2017/01/ESC_logo-300x352.pngMorgan Jackson2012-07-25 06:00:202019-11-14 20:21:44CJAI #19 – Cluster flies of North America
We had a great response to last week’s photo, so thank you to everyone who played along. We’ve got an all new photo for you to caption today, but first we need you to vote for your favourite Photo 1 caption.
ESC Caption Contest C1 P1
We’ll post the results and award some points next week.
Copyright for the photo remains with the photographer, use must be granted for ESO promotional material. Winning photos will be displayed on the ESO website, and all entries will be displayed at the 149th Annual General Meeting of the ESO.
Interested in meeting other entomologists and learning more about Ontario insects? Join ESO! It’s free for students and amateurs, and only $30 for others. Get more information at http://www.entsocont.ca.
1. Photos must be of insects or closely-related arthropods (e.g. mites, spiders).
2. Submissions must be as digital files
3. Photographic enhancement is allowed as long as it is something that could be achieved in a real darkroom (i.e. adjustment of contrast, color enhancement, cropping, etc.). However very obvious enhancements will be negatively scored.
4. You may submit up to 3 unique images per category.
5. Submit photos as 7.5 x 10 inches in size at 300 dpi (2250 x 3000 pixels), in .jpg format, with filename as title_lastname_firstinitial.jpg (e.g. dragonfly_smith_j.jpg).
6. Photos may be landscape or portrait in orientation.
7. Print photos must be scanned and submitted as digital files.
Please include a short description of your photo:
1. Where they were taken
2. Why you like them
3. What insect is pictured
4. What category is being entered
5. Your complete address
1. Image composition
2. Visual impact
3. Subject interest
4. Sharpness of subject
5. Difficulty of image acquisition
6. Depth of field within image
Dear Buggy is the the alter-ego of Dr. Chris MacQuarrie, a research entomologist with the Canadian Forest Service. You can ask Buggy questions of your own on Twitter @CMacQuar.
Dear Buggy has lept out of the pages of the ESC Bulletin and landed in the new and exciting wilderness of the ESC blog. My loyal readers shouldn’t worry, I’ll still be writing my column, but between editions of the Bulletin I’ll be posting here.
I’m very excited to be contributing to the ESC blog, but I’ll admit I am a tad nervous. When Crystal and Morgan invited me to contribute I was worried that it would be hard to come up with interesting topics. Thankfully the ideas began to flow after a glass of good scotch and I think I’ve come up with a few ideas that should keep me busy. After that? Well I’m always open to suggestions.
While thinking about this first blog post for ‘Dear Buggy’ I recalled how I felt when I first signed on to write Dear Buggy for the Bulletin. Where was I going to get these ideas!? Fortunately, a lot of the suggestions for my early columns come from the then-editor, Kevin Floate. Kevin had the original idea for Dear Buggy and shared with me his collection of questions and ideas. Later on, the ideas began to flow and inspiration came from others around me. Although, when I’m stuck for an topic I still go back to the original list that Kevin gave me. Good ideas can be hard to come by when you’ve got writer’s block and a deadline is fast approaching
As I planned this blog post I began to muse over the source of all my ideas, in particular “Where do I get my research ideas?”.
For example, when I was a new MSc student many of my research questions were influenced by the ideas of my supervisors. This isn’t all that unusual. I suspect that when most of us started in research we were given, or at the least influenced, by ideas of others. As we mature scientifically we eventually start to come up with our own ideas. In fact, a good part of becoming a successful, independent researcher is tied to coming up with good ideas (which we might also call hypotheses). So where do these ideas come from? And perhaps more importantly, what do we do with these ideas once we have them?
I find inspiration hits at the oddest times and in the oddest places . I think Jorge Cham at PhD comics captured it best in thisseriesof comics. Like most, I’ve been inspired in the ‘usual’ places: reading papers, attending seminars, talking with colleagues, etc… But inspiration can happen in other places as well. My mind tends to wander on my bike-ride home, when I’m pushing my daughter in her stroller, and quite often when I’m sharing a glass of scotch with my wife (who, lucky for me, is also an entomologist). As it turns out, this ‘mind wandering’ actually helps you have those ‘eureka’ moments, especially if you have been banging your head against the wall for awhile. I wrote recently about figuring out when you are best at writing. I think that advice can be extended to figuring out when and where you are inspired and to make sure you go there often.
But what about capturing ideas? My mind is like the proverbial sieve, but with one annoying quirk. I often can remember that I had an idea, I just can’t remember what it was.
To combat this selective memory I try to capture my ideas in my work journal as soon as possible. I’m a bit old fashioned so my journal is still kept in a notebook. Since my journal is also where I keep track my current projects, I make sure I highlight any new ideas so they are easy to find later on. There are many, many web-tools out there that can do the same job. The trick, though is to find something that works for you and to use it. My wife, for example, is also an artist and long-ago got in the habit of carrying a sketchbook with her. That sketchbook now contains just as many ideas for research projects as it does ideas for art projects.
Finally, I must make a confession. Most of my ideas are bad. Some are half baked, others were thought of by someone else and rejected 30 years ago, a lot are impractical, infeasible, or near-impossible to execute or fit into the research that I’m doing. These over time get filtered out. Those that survive this process of natural selection, I keep. I then draw from this storehouse when the right moment comes along. Not all of these ideas will pan out of course, but by hanging on to the good ones I always have the right idea at hand when opportunity presents itself.
I’d be curious to hear about where you find your inspiration and how you track your ideas. Leave them in the comments section and I’ll summarize the best ones in a later post.
http://esc-sec.ca/wp/wp-content/uploads/2017/01/ESC_logo-300x352.png00Morgan Jacksonhttp://esc-sec.ca/wp/wp-content/uploads/2017/01/ESC_logo-300x352.pngMorgan Jackson2012-07-18 06:00:322019-11-14 20:21:31Dear Buggy: Where Do Research Ideas Come From?