How much can you tell about a wasp’s life when all you have are dead specimens that are over 30 years old and smaller than a grain of rice?

If you have a morphologist and a good microscope, you can actually tell a lot.

When we took a look at four tiny wasps collected in Costa Rica in 1985, we knew immediately that we were dealing with a new species. It was clear that the species belonged to the genus Dendrocerus based on the dark patch on its wing, called a pterostigma, and the numerous long branches of the male antennae.

However, we didn’t know of any Dendrocerus, or any wasp in the superfamily Ceraphronoidea, that had a row of mesoscutellar spines, shown with an arrow in the picture below.

What could these mesoscutellar spines be used for?

Like many wasps, ceraphronoids are parasitoids, meaning that their larvae feed on a live host insect. Some are endoparasitoids, which lay their eggs inside a live insect so that the larvae can eat it from the inside out. After they’re done feeding, endoparasitoid larvae may stay inside their hosts body to complete their development. Once they are mature, the adult wasps will then push or chew their way out.

Dendrocerus scutellaris is the only known ceraphronoid with a series of mesoscutellar spines, but this is not the only feature that sets it apart: whereas other ceraphronoids have pointed mandibles, D. scutellaris has blunt, flattened mandibles. With its blunted mandibles, D. scutellaris cannot chew its way out of a host.

This may be why the wasps have these spines; while emerging from their host, the wasps may rub the spines against the host’s body to help break or saw their way out. Similar structures have been found in other insects, including Hymenoptera and Lepidoptera.

For more about these wasps, check out our new publication:

Trietsch C, Mikó I, Notton D, Deans A (2018) Unique extrication structure in a new megaspilid, Dendrocerus scutellaris Trietsch & Mikó (Hymenoptera: Megaspilidae). Biodiversity Data Journal 6: e22676. https://doi.org/10.3897/BDJ.6.e22676

This material is based upon work supported by the U. S. National Science Foundation, under Grant Numbers DBI-1356381 and DEB-1353252. Any opinions, findings and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.

This post is the fourth in a short blog series featuring important figures in the history of natural history.

René Descartes (1596-1650) was a scientist, mathematician and philosopher. He is regarded as the father of modern western philosophy, and is the man behind the statement Cogito ergo sum, translated as “I think, therefore I am”. So why should scientists know and care about him today? Because Descartes changed science by changing the way humans think about the natural world.

Before Descartes, doctors and scientists were trained to study the world through the lens of Aristotle’s works. They followed Aristotle’s philosophies on the cosmos and the soul, and believed that all matter was comprised of the four elements (earth, water, air and fire), which corresponded with the four humours of the human body (black bile, phlegm, blood and yellow bile). An imbalance in the humours was thought to cause illness, so doctors would try to treat sick patients by balancing the humours, leading to practices such as bloodletting.

These scientists and doctors sought to understand nature by studying the cosmos and the soul, but Descartes argued that we can never know what the soul is. Instead, Descartes thought to study life by studying the mechanisms behind it. His Discourse on Method (1637) encouraged scientists to question and test hypotheses through the use of experimentation and deductive reasoning.

Descartes was responsible for a paradigm shift in how humans think. It was Descartes who instructed scientists to focus on fact, not on the abstract, paving the way for modern science.

Insects don’t have hearts like the rest of us. Instead of a multi-chambered heart, they have a dorsal vessel with multiple chambers separated by valves called ostia. A substance called hemolymph, which functions similarly to blood, gathers in these chambers, which are contracted by wing-shaped alary muscles to pump the hemolymph from the abdomen towards the head.

While humans have a closed circulatory system where all of our blood is contained in arteries and veins, insects have an open circulatory system where hemolymph flows freely through a cavity called the hemocoel. The hemolymph then gathers in the chambers of the dorsal vessel and is pumped back up towards the head, so that the brain and other major organs can be bathed in the nutrient-rich hemolymph. The hemolymph continues to flow down through the rest of the body, until it gathers back in the chambers, repeating the process.

Is hemolymph the same as blood? Not exactly. While our blood carries oxygen to our cells, insects don’t need this: they have a separate system of tubes called trachea that allow oxygen to reach their cells and carbon dioxide to be released. Instead of transporting oxygen, hemolymph transports nutrients around the insect’s body. Hemolymph also carries immune cells called hemocytes,  playing an important role in an insect’s immune system.

You can see the dorsal vessel in action in the tobacco hornworm below:

Special thanks to Anne Jones and the Tumlinson Lab for allowing me to poke, photograph and video their Manduca sexta.

The Deans lab just got back from Denver, Colorado, where we attended the yearly annual meeting of the Entomological Society of America. This meeting is the largest meeting of entomologists in North America, with over 3,500 attendees this year! There are many other societies that also meet at the same time, including the Entomological Collections Network (ECN) and the International Society of Hymenopterists (ISH), making this a great opportunity to make new collaborations and keep up to date on what’s happening. If you are an entomologist, ESA is the place to be!

The theme of this year’s ESA meeting was scientific outreach and communication. This is particularly important for entomologists because insects are a part of everyone’s life, whether as study organisms, as pests, or as that interesting creature you happened to see on your morning walk. Insects are everywhere, so it’s easy to do outreach and spread the word about how important and interesting insects are.

The Deans lab gave some strong talks this year. Emily spoke of her odonate research in a talk titled “Burrowed in natural history: Analysis of life stage collection in Gomphidae”, while I gave an update on my Ceraphronoidea work in “Mysteries of Megaspilidae: Conostigmus spp. (Hymenoptera: Megaspilidae) of the Nearctic.” Istvan also gave a talk  on using Big Data in natural history research, titled “Querying semantic phenotypes with transcribed specimen data.” The Deans lab also produced a flurry of posters for both ESA and ECN, including “Pests in the Collection: What is normal?”, “The Insect Collectors’ Code”, and “Aphanogmus male genitalia and confocal laser scanning microscopy.”

The conference was also a great opportunity to catch up with old friends. We ran into one of our former Frost interns, Isa Benacourt, who is the now the Communications officer for ECN and gave her first conference presentation ever on the use of interactive live broadcasting for entomology outreach using the platform Periscope. Congratulations, Isa!

Overall, it was a great opportunity to meet up with old friends and make new collaborations. We’re looking forward to next year’s meeting in Vancouver!

Check out Andy’s post, and keeping checking back for more posts from the other Frost members about their ESA experiences.