Researching Pelecinids – Part 2

One of the most useful resources the Triplehorn Insect Collection has to offer is its extensive HOL database, an online taxonomic initiative that documents collected specimens of various insect groups. This database already contains records for over 845 thousand Hymenoptera specimens, and it continues to grow every week through the hard work of countless contributors.

One way to contribute to HOL is to photograph and upload images of collected specimens, further enriching the available data on specific taxa. Prior to the start of my research on pelecinids, there were zero images of the genus Pelecinus available in the database. To remedy this, I had the opportunity to work with Jordan Reynolds, an undergraduate student in Art & Technology who is currently working on specimen photography for the collection. Over the last several weeks, Jordan taught me about the technologies and techniques required for taking high-quality images for the database.



My goal in photographing a selection of the collection’s Pelecinus polyturator specimens is three-fold. First, I will obtain a more in-depth understanding of the external anatomy of these intriguing insects. Second, I can compare the morphologies of males and females of different sizes and localities. Third, I will contribute previously unavailable data to the HOL database.

Photographing collection specimens is not as simple as taking a picture with a camera. Because the specimens are relatively small, and because we require intricate detail in the images, we instead use a method known as focus stacking. With this method, the camera gradually moves along a track and takes multiple images at different distances. The focused areas of each image are then “stacked” together by a computer program so that the entirety of the final image is clear. Because the P. polyturator specimens required a large depth of field, we sometimes had to photograph and stack up to 100 images to create a sufficiently focused final image.

In addition to taking individual specimen images, we also took several comparison images. These provide a quick side-by-side comparison between two different specimens. Some of the images we took compare males and females of similar localities. Other images showcase females of similar localities and their dramatic variance in size.

comparison image of P. polyturator females

Comparison image illustrating the size variation in P. polyturator females

Of course, no system is perfect, and we faced many challenges along the way. Most of the parasitic wasps that get photographed by the collection are very small in size (no more than a few millimeters long). Therefore, the collection’s microscopic camera that is traditionally used for parasitoid photography is designed to take highly detailed images of very small specimens. P. polyturator females are unusual in that they are very large parasitoids that can exceed 40 mm in length. Because of this, many of the specimens we wanted to photograph could not fit under the microscopic camera. We instead opted to use a DSLR camera, which is used for macrophotography of larger specimens such as beetles and butterflies. Using this nontraditional method of parasitoid photography, we were able to produce high-quality images of the larger specimens by exploiting various imaging techniques.

Another challenge we faced was the handling of the specimens. All mounted insects in a collection must be handled with great care because they are dry and brittle. Pelecinids must be handled with extra caution because their long, string-like antennae and fragile abdomens will break with even the slightest bump.

We ended up with many beautiful images of these wasp specimens. The complete collection of images has been uploaded to HOL and is available on the page dedicated to P. polyturator. I would like to thank Jordan for all of his help with this photography endeavor. Without the countless hours he spent performing behind-the-scenes image processing, the final images could never have turned out so well.


About the Author: Hannah McKenzie is an undergraduate entomology major at the Ohio State University. She currently works at the Triplehorn Insect Collection and is participating in undergraduate research on Pelecinus wasps.

Love (and re-curate) thy beetles

Specimen of six-spotted tiger beetle (Cicindela sexguttata F.), one of the species of ground beetles recently re-curated.

Specimen of six-spotted tiger beetle (Cicindela sexguttata F.), one of the species of ground beetles recently re-curated.

The Triplehorn Insect Collection is one of the largest university collections in the USA, holding about 4 million dry, mounted insect specimens, with many thousands more being added each year. The collection grew from the research collections of Ohio State faculty, curators, and students, dating back to the late 1890’s, when the university’s first entomologist, Herbert Osborn, was hired. Our specimens are used for research purposes by scientists from the USA and abroad.

Because of the age and the history of the collection, we have a very significant curatorial issue: an abundance of 70+ year old storage units, including the drawers and the trays that still hold most of our specimens today. These drawers and unit trays were the standard way back when, but are now considered, for various reasons, to be unsuitable for the long-term preservation of our specimens. The drawers, too shallow and with loose-fitting lids, and the unit trays, in various odd sizes, made of paper and lined with cork or wood, need to be replaced with standardized, museum quality materials.

Old unit trays.

Changes in costs and materials available over the years resulted in the use of a wide variety of now substandard materials. Notice the uneven size and shape of unit trays. Specimens are tightly packed due to earlier space restrictions.

Cork lined unit tray

Cork bottom unit trays such as this make it very difficult for staff and visiting scientists to handle specimens. Hard bottom does not fit properly, leaving large gaps around the edges of the unit tray.

Over the years, many of the insect pins have corroded and become solidly “trapped” in the cork pinning bottom. To add insult to injury, due to the chronic lack of storage space that affected the collection for most of our history, the old unit trays are ultra overpacked with specimens. That storage situation makes the handling the specimens for study and curation a very time-consuming, damage-prone operation.

In 2009 we secured a $415K collection improvement grant from the National Science Foundation to install a compactor storage system in the collection, develop a primary type database, and to make progress on rehousing specimens in new drawers and unit trays.

New compactor system

View of the compactor system installed at the Triplehorn Insect Collection in 2009.

Since then a lot of curatorial work has been happening here. The re-curation process (i.e., moving the specimens & upgrading the curatorial status) involves four major steps, each deserving of a separate post, but here they are in a nutshell: 1) updating the taxonomic names associated with the specimens; 2) transferring specimens to new unit trays; 3) reorganizing and storing specimen unit trays in new, tightly closed, naphthalene-free drawers; and finally 4) databasing the specimen information.

We started the re-curation by diving head-first into the beetles (order Coleoptera), the most extensive, well-studied, and heavily used group of insects in our collection. The beetles, all 65 cabinets, 1600+ drawers of them (almost 20% of our collection!), are a massive curatorial challenge for our small and young staff. But what we don’t have in numbers and experience, we make up in care, enthusiasm & dedication.

Replacing the old unit trays is by far the most difficult part of the process. It involves gently, but firmly extracting each of the specimens from the old unit trays and transferring them to new, foam-lined trays. The process requires skill, patience, but most of all, discipline to resist the (sometimes almost overwhelming) urge to simply yank the specimens out of the old unit. Brute force, though tempting at times, is a big no-no in curation, and can only bring (curatorial) grief & (specimen) destruction: picture insect body parts, pins, and even bits of cork, flying across the laboratory – a complete curator’s nightmare.  So, rule #1, no brute force. In the cases when the specimens are completely stuck, we use insect pliers (much like dentist’s pliers) to break the grip of the cork on the pin.

Insect pliers

Insect pliers are used to gently pry specimens off the hard bottom unit trays without causing damage.

Once freed, the specimens are placed in new, acid-free, foam lined unit trays. The foam works much like a bug “pin cushion“, allowing for easy handling of the specimens in and out of the unit tray. The unit trays with the specimens are subsequently stored in new, tightly-sealed insect drawers.

Unit trays and drawers are carefully labeled according to the most updated taxonomic information for maximum accuracy and organization. To fulfill our commitment of making specimen level information freely available online, we transcribe and add the specimen information to our database. (More on databasing on a subsequent post).

New unit trays, with foam liner and header labels color-coded according to biogeographic region.

New unit trays, with foam liner and header labels color-coded according to biogeographic region.

So far 39,388 beetle specimens in 1,696 taxa, including all the ground beetles (family Carabidae), have been transferred to new storage units and drawers. Of those, 21,476 specimens (a whopping 55% of the total) have already been barcoded, databased, and are available online for your perusal. The others are still being worked on.

The bulk of this unnervingly tedious, extremely delicate, outrageously detailed, AND dramatically important piece of curatorial history at the Triplehorn Insect Collection is being executed by a team of carefully trained, skilled undergraduate curatorial assistants working under the supervision of the collection’s permanent staff.

Many interesting problems and issues have arisen during the re-curation process, some known to us, and some completely unexpected. We’ll be talking more about curatorial issues in subsequent posts.

In order to evaluate the efficiency and to quantify the costs of the re-curation process, we have been keeping detailed records of all our activities. We presented a preliminary report of our work at the 2012 Annual Meetings of the Entomological Society of America in the form of a poster. (PDF copy here)

References:

L. Musetti, S.E. Hemly and N.F. Johnson. “Quantification of the costs of insect collection curation.” Poster Presentation. Annual Meeting of the Entomological Society of America. 13 November, 2012. Knoxville, TN.

 

About the Author: Dr. Luciana Musetti is an Entomologist and Curator of the Triplehorn Insect Collection.

First words

Hello, and welcome to the Pinning Block!  Here we’ll share stories about the Triplehorn Insect Collection:  the people who built (and build!) it, the researchers who use (and sometimes abuse) it, the visitors who delight in it, the long-term friends of the collection who support us, and, of course, the exciting work we do.  Since we are an insect collection, a lot of what we will blog about is related to the care of the collection, which we broadly call curation.

For those who are not familiar with it, a pinning block is used to position an insect specimen, as well as the labels associated with it, at uniform heights on an insect pin.  It is a beautifully simple and indispensable tool in an insect collection.

Pinning blocks are used to position specimen labels at uniform heights on the insect pin.

Pinning blocks are used to position specimen labels at uniform heights on the insect pin.

Not only is the appearance of the collection vastly improved when all the specimens and labels are mounted at a uniform height on the pins, but the preservation of the specimens and the accessibility of the collection is greatly enhanced as well. And this is what insect collection curators strive most to do: to keep their specimens safe and make their collections more accessible to the people who need to study them.

Over the last few years, warm, wooden blocks have been replaced by cool and apparently indestructible pieces of steel, cut with precision tools. But independent of the material it’s made from, the pinning block is a metaphor for the attitude we have towards our work: simple, clean, and to the best of our capacity, efficient.

This blog will hopefully be a collaborative effort of the faculty, staff and students associated with the collection. Our goal is to share the joys and tears, the excitement and drudgery of the work we do, but ultimately to share how biological collections in general, and the Triplehorn Insect Collection in particular contribute to the university’s missions of teaching, research and service.

About the Author: Luciana Musetti is an Entomologist and Curator of the Triplehorn Insect Collection.