The Department of Entomology is made up of dedicated staff members from the Smithsonian Institution, USDA Systematic Entomology Lab, and Walter Reed Biosystematics Unit. In an effort to introduce these enthusiastic scientists and promote the important work they do, we present our inaugural "Meet The Scientist" post, featuring Smithsonian dipterist Dr. Torsten Dikow. We asked Dr. Dikow some questions about how he became an entomologist at the National Museum of Natural History, and the flies that he works on.
Q: Why did you decide to become an entomologist?
A: When I was finishing up my high school equivalent in Germany, where I am originally from, I met up with local naturalists as I had always been interested in biology and was planning to study biology at university. The majority of these amateur scientists were entomologists and I quickly became interested in insects, mostly because of the large number of different species to be found in forests locally. What I liked was that one could easily observe and identify the common species even in the field.
Q: What made you interested in flies, and robber flies in particular?
A: After the second semester at university, I signed up for a field course in systematic botany and zoology where each student had to prepare a collection of plants, aquatic arthropods, or insects. I decided to use this opportunity to enlarge my insect collection, but to not focus on beetles, which I had done so far, and rather collect other insects to broaden my knowledge of the local fauna. By chance, I collected a few robber flies and after identifying them to family and talking to my professor about them I got immediately hooked and decided that I would focus on assassin flies from now on. Luckily, a web-site with a wealth of information on these flies (http://robberflies.info) had just been posted by a German entomologist who helped me to get started with literature and with whom I am collaborating to this day.
Q: What are robber flies and where do they live?
A: Robber flies, or assassin flies and scientifically Asilidae, are predatory flies that catch other insects on the wing as food. The flies are very good flyers and can even catch prey insects much larger than themselves. They have very large eyes as visual predators and range in body size from 5–60 mm (0.2–2.4 inch). Today we know of more than 7,500 different species found throughout the world in temperate regions like DC, in deserts such as those found in Arizona and southern California, and in tropical rainforests. Interestingly, assassin flies are absent from Hawai’i, where other insects are known from many species, but they live on other Pacific islands such as Fiji or French Polynesia. Every entomologist knows what an assassin fly is because they are usually easily seen in the field (at least the bigger species) and everybody likes to catch them because it’s a challenge to get these fast flying flies in your net.
Q: How did you come to work at the National Museum of Natural History?
A: During my university years in Germany I decided I wanted to study abroad to improve my English and to do this somewhere where there was going to be a much larger diversity of insects and life in general. So I enrolled at a university in South Africa and took every entomology course I could. While there I learned about the then called Research Training Program (now Natural History Research Experiences http://www.mnh.si.edu/NHRE/) here at the museum and applied for the 10-week summer internship. Luckily, I was selected and was able to work with Dr. Wayne Mathis in the Diptera collection on a small taxonomic revision of a shore-fly genus, which we published a few years later (see http://www.biodiversitylibrary.org/pdf2/001809600054767.pdf). During my internship I obviously met many other fly researchers and among them Dr. David Grimaldi from the American Museum of Natural History in New York City who later became my advisor of my Ph.D. After finishing my Ph.D. and spending 4 years at the Field Museum of Natural History in Chicago, IL as a postdoctoral fellow, I applied for my current position as Research Entomologist of Diptera that in a way was filling the vacant spot that Dr. Mathis had left after he retired. I am extremely happy and honored to have this position here at the NMNH and this is my dream job.
Q: What does your research focus on and what kinds of methods/techniques do you use?
A: My research focuses on deciphering the diversity and evolutionary history of asiloid flies. This includes assassin flies, but also their most closely related families called flower-loving flies and mydas flies, which are not predators, but feed on pollen and nectar (http://asiloidflies.si.edu). I use both morphological and molecular data to decipher the evolutionary relationships. I also describe new species of flies and have so far named 67 new ones.
Q: What is the backstory of the amber specimens featured in your recent paper?
A: Insects in Burmese amber, a 100 Million year old amber from northern Myanmar (formerly known as Burma) in south-east Asia, have been known for a long time. My co-author Dr. Grimaldi has described many insects from this amber over the past two decades, but he had never seen any assassin flies, which are always rare in amber. This is most probably so because these flies are very strong and don’t get entrapped in tree resin, in contrast to midges, for example, which can’t escape once stuck. A colleague from the Australian Museum in Sydney contacted me a few years ago about a robber fly in this amber shown to him by a private collector in Australia. I immediately contacted Dr. Grimaldi and asked whether he could purchase the specimen for the extensive amber collection at his museum in New York so that we could study it. He did, and a few months later I started to work on this piece in which a single male specimen was entrapped. I had difficulty finding good features to find out to which other robber-fly species this specimen was related to. Then, Dr. Grimaldi found a second piece with a robber fly in Burmese amber from a collection he had just obtained and this time it was a female. This was great, as we now had both sexes and the particular structures with which the female laid its eggs provided evidence to us to formulate a hypothesis of the most closely related robber flies.
Q: Why is this discovery significant?
A: The finding of a robber fly in Burmese amber is by itself already outstanding. This fly with a very unique set of features not found in any existing assassin fly also gives us a window into the past of the family Asilidae that we wouldn’t be able to obtain otherwise. For example, there is an older assassin fly, Araripogon axelrodi, known from the so called Crato Formation of north-eastern Brazil (112 Million years old), but this species is preserved in limestone and a very limited number of features can be observed and none of them in three dimensions. (I should mention though that I am working on examining this fossil with micro-CT scanning techniques so that we can get a three dimensional model of it.) Furthermore, Burmapogon bruckschi will provide a time slice along with other amber fossils I am currently studying with which we can study the diversification of assassin flies with molecular data, which is really exciting.
Q: Last question: if you could be any insect, living or extinct, what would you be, and why?
A: Ugh, insects are so diverse and I really enjoy observing them in the field when I am conducting field work. My favorite places to go for field work are deserts so it has to be an insect that lives there. Flower-loving flies, Apioceridae, fit the bill: they are cute looking, resembling assassin flies somewhat, they are only found in the dry environments of western North America, Australia, Chile, and South Africa, and therefore I would want to be one of them.
To learn more about Dr. Dikow's research, please visit his page on our department website.
Torsten Dikow, Jessica Bird, & Erin Kolski, Department of Entomology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.