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Exploring piophilid flies: taxonomic tools for forensic entomology

By Sabrina Rochefort, MSc student, McGill University.

Early in my undergraduate program at McGill University, I was looking for an opportunity to volunteer in a lab, where I could feed my need to learn and make new discoveries. That led me to Terry Wheeler’s lab; he was the teacher for my evolution class at that time.

I had a strong interest in evolution and paleontology, and was hoping to pursue that field. But Terry informed me that volunteering in his lab did not involve studying fossils, but instead studying tiny insects. Curious and willing to learn about insects, I decided to give it a try! At the Lyman Museum, I quickly discovered that entomology is a field of study with great opportunities and with an infinite number of projects. Besides studying for my degree, and working on weekends at Tim Hortons, I was volunteering up to 12 hours a week, between and after classes, pinning flies and identifying them. I couldn’t lie to myself anymore, I had developed a strong passion for entomology!

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Identifying flies at the Lyman Museum. Photo by E. Vajda

 

Volunteering gradually transformed into a student job. It’s then that Terry introduced me to the fly family Piophilidae, commonly known as the Skipper Flies. I spent numerous hours familiarising myself with piophilids, reading literature, learning to identify them, their ecology, etc. All that knowledge that I acquired in entomology during my undergraduate studies gave me a great opportunity: the chance to pursue graduate studies. I am presently undertaking a Master’s project on the taxonomy and phylogeny of Piophilidae.

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Collecting piophilids on decaying mushrooms in the Yukon. Photo by E. Vajda

 

Now, let’s put a little less attention on my background and a little more on this wonderful family of flies and my project!

Piophilids are small to medium flies (3 to 9mm), which are abundant and diverse, especially in the northern hemisphere. To date, there are 82 described species worldwide. They mainly feed and reproduce on decaying organic matter. This family is of interest in several scientific domains such as forensic entomology (for their presence on carrion), in behavior (for their unique sexual selection strategies) and in biodiversity (for their interesting geographic distribution in the arctic). Several species are also pests in the food industry. The study of their taxonomy and phylogeny is essential for several reasons: to be able to identify specimens found in studies; to document the geographic distribution of species; to establish their phylogenetic relationships; and to learn more about their biology and ecology. The main objectives of my thesis are a taxonomic revision of the Nearctic Piophilidae and phylogenetic analysis of the genera worldwide.

Liopiophila varipes, a piophilid species commonly found on carrion. Photo by S. Rochefort

Liopiophila varipes, a piophilid species commonly found on carrion. Photo by S. Rochefort

A statement that is often repeated in our lab is that it is important for taxonomists and ecologists to collaborate, and that the outcomes of our taxonomic projects should be useful not only for taxonomists but also to other entomologists in other fields of expertise. And that is right! For taxonomy to make sense, it is essential that other researchers be able to understand it and use our work. This can be done by providing them with “working tools” such as identification keys which are simple and adapted to a specific need. It is for that reason that, as a side project to my thesis, I decided to collaborate with Marjolaine Giroux, from the Montreal Insectarium, Jade Savage from Bishop’s University and my supervisor Terry Wheeler on a publication and key to the Piophilidae species that may be found in forensic entomology studies in North America. That paper has just been published in the Canadian Journal of Arthropod identification. We reviewed some of the problems associated with identification of piophilids, and the need to develop a user-friendly key to the species. We wanted to create a key with lots of photographs, that was user-friendly and simple for non-specialists, and that would be published on-line and open access. Because of this, CJAI was the ideal journal for our paper.

Seeing this publication completed early in my graduate studies is a great accomplishment for me. It gave me the opportunity to share my knowledge and make taxonomy more accessible to students, amateur entomologists and researchers in the academic and scientific community. Undertaking a project in a less familiar field which is linked to your expertise is a very gratifying experience which I strongly encourage other students to try. From this experience, I acquired new skills and knowledge, I made connections with researchers in other fields of study and I was able to make more connections between my Master’s thesis and other subjects in entomology.

Reference

Rochefort, S., Giroux, M., Savage, J., Wheeler, T.A. 2015. Key to Forensically Important Piophilidae (Diptera) in the Nearctic Region. Canadian Journal of Arthropod Identification No. 27: January 22, 2015. Available online

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Ants of Alberta – Technical Editor’s Pick CJAI 22

Earlier this summer, a new key and review of the Ants of Alberta was published in the Canadian Journal of Arthropod Identification. James Glasier, the lead author, was kind enough to answer a few questions about the work, and share some of the species he thought were particularly interesting.

Couplet 3 from Glasier et al. 2013

1. What inspired you to produce this key?

The key was inspired by the difficulty of finding coherent, up to date, and all-encompassing keys for the ant fauna of Alberta. It started as a side project, to help me better understand the differences among ant species I was finding during my thesis research.  As it developed, we realized that a key formatted for the Canadian Journal of Arthropod Identification would greatly benefit anyone who wanted to study ants in the province. So with the help, guidance, and contributions of my co-authors, we developed to identify all known ants from Alberta.

2. Who do you think is most likely to use your key to the Ants of Alberta?

The coauthors and I hope that anyone who is interested in ants uses the key.  We think that in Canada, ants are too often ignored in biological studies and with this key we hope more people will include them in their research.

3. Rather than provide individual accounts for each species, you’ve linked out to the species profiles in AntWeb. Why did you decide to do it this way, and what advantages does AntWeb have over traditional publishing?

We decided to link the key to AntWeb, because AntWeb has fantastic photos of ant specimens and they are always updating their photo catalog.  It is hoped that these photos work in concert with the key we have developed and better aid identification of ant specimens.  Additionally, AntWeb has an online specimen catalog and natural history sections, which is easily accessed and continually updated to provide current information about each ant species.

4. Were there any ants that you were surprised to find in Alberta?

The most surprising was species was the neotropical ant Brachymyrmex obscurior; found in the Olds University Atrium by Dr. Ken Fry.  For better or worse, the colony seems to have died out. Another surprising ant species was found by John Acorn, Dolichoderus taschenbergi. This ant is a rather obvious ant when you are out in the field; workers are black and very shiny, and in the morning will all congregate on their nest to sun themselves.  The effect of hundreds of workers covering a ~30cm2 area is an obvious sparkling mass of black.  Yet, with over 30 years of work by multiple researchers in the Opal Sand Hills, including John, no one recognized that this species was present until our ant project began.

Dolichoderus taschenbergi – Photo by April Nobile, courtesy of AntWeb.org (CC BY 3.0)

Glasier, J.R.N., Acorn, J.H., Nielsen, S., Proctor, H. 2013. Ants (Hymenoptera: Formicidae) of Alberta: A key to species based primarily on the worker caste. Canadian Journal of Arthropod Identification No. 22, 4 July, 2013. Available online at http://www.biology.ualberta.ca/bsc/ejournal/ganp_22/ganp_22.htmlhttp://dx.doi.org/10.3752/cjai.2013.22

Dufourea bee on flower
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CJAI #20 – Dufourea (Apoidea: Halictidae) of Canada

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By Sheila Dumesh, entomology research assistant at York University.

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My interest in bees was ignited in 2007, when I took a biodiversity course in my last year as an undergraduate student at York University in Toronto.  The course instructor was the well-known melittologist, Laurence Packer, and, although I had not met him before, I had heard many good things.  Laurence’s affection for bees was inspiring, not only to me, but to others in the past and many more to come.  He was so fascinated by these cute and fuzzy insects (at the time, I did not see myself describing them as such).  Even though he had been studying bees for decades, the look of excitement on his face never faded when collected and examined them.  Back then, my knowledge of bees was very limited.  I was unaware of their diversity, importance, and great beauty!

I began with an Honours thesis under Laurence’s supervision in the “bee lab” at York University.  I was keen on taxonomy and began a systematic study on a Central American bee genus, Mexalictus.  For my Master’s thesis, I chose to continue that work and complete a revision of Mexalictus, which included descriptions for 20 new species, an illustrated key, and a phylogenetic analysis.  I conducted my field work in Costa Rica, Guatemala, and Mexico, where I sampled in high elevation cloud forests (the known habitat of Mexalictus).  As these species are quite rare, I did not always have the pleasure of finding them; although this was somewhat upsetting, I was amazed by the bee (and general insect) diversity in that part of the world.  I was aware of it, but being out in the field in those countries was a truly amazing experience.  Just the change in habitat and species make-up along a small sector of the elevation gradient was incredible to witness!

Dufourea bee on flower

Dufourea sp. – Photo by Sheila Dumesh

Throughout my time as a Master’s student, I studied other groups of bees and collaborated with others in our lab.  One such project is the revision of the Canadian species in the genus Dufourea (Apoidea: Halictidae), which I undertook with Cory Sheffield and recently published in the Canadian Journal of Arthropod Identification.  There are eight species in Canada, but some were described from only one sex, the descriptions were written by several authors in different publications, and a key to identify these species was previously unavailable!  These bees are also floral specialists, meaning they visit specific flowers (usually a genus or family).  Cory and I set out to revise this group and provide all of this information in one paper.  The identification key is user-friendly and illustrates the characters mentioned in the key couplets to aid the user.  We also constructed species pages, which include full descriptions, important features, distribution maps, and images of each species.

We are striving towards creating many more illustrated (and web-based) keys to facilitate bee identification.  I am very excited to have this work freely available and hope that it is found useful by others in the community!

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Dumesh, S. & Sheffield, C.S. (2012). Bees of the Genus Dufourea Lepeletier (Hymenoptera: Halictidae: Rophitinae) of Canada, Canadian Journal of Arthropod Identification, 20 DOI: 10.3752/cjai.2012.20

Pollenia griseotomentosa Calliphoridae Cluster fly
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CJAI #19 – Cluster flies of North America

Pollenia rudis Face

Pollenia rudis

By Adam Jewiss-Gaines,  a research assistant at Brock University.

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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.

Pollenia griseotomentosa Calliphoridae Cluster fly

Pollenia griseotomentosa

Until very recently it has been thought that all Pollenia found in North America were the same species (Pollenia rudis), 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.

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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.