Watch a caterpillar pump blood—er, hemolymph

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.

A figure illustrating the dorsal vessel and the ostia in a tobacco hornworm, Manduca sexta. The dorsal vessel contracts to pump hemolymph from the base of the abdomen to the head. Photo by Carolyn Trietsch (CC BY 2.0). Click for source.

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.

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Deans lab in Denver! ECN and ESA 2017

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 Big Blue Bear at the Colorado Convention Center. Photo by Carolyn Trietsch (CC BY 2.0) Click for source.

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 Insect Collector’s Oath, a poster presented at ESA. Photo by Carolyn Trietsch (CC BY 2.0). Click for source.

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.

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ECN, ESA, and other thoughts

I’ve been back for just over a week now, from an awesome trip to Denver for the Entomological Collections Network (PDF) and Entomological Society of America annual meetings. My lab group presented several talks and posters, which you can read about soon in Carolyn’s post (and congrats to her for being runner up for the 2017 President’s Prize!), and overall it was a fun and exciting event. There were many highlights, of course, too many to discuss in one post, and ECN and ESA seem more vibrant and diverse than ever. We also got important feedback regarding our presentations and the research issues we’ve been exploring here at Penn State. A couple thoughts, while they’re fresh in my mind:

(1) Non-human visitors in the museum. What’s normal?

We’ve established a rigorous pest monitoring and IPM strategy here at the Frost (SOP 2 of our policies and procedures), and we presented some of our results and questions (DOI: 10.6084/m9.figshare.5566732.v3), including results of a short IPM survey we sent to ECNers. We’re still analyzing the responses and feedback, but a couple things are clear:

  1. The community wants more science-based collection IPM recommendations. It may be difficult to do this robustly, given the heterogeneity of collection environments, but I definitely see opportunities for fun undergrad experiments.
  2. Our collection room has more outside “visitors” than most museums. Another mission of this survey was to gather the data we need to argue for better space. Given how “leaky” Headhouse III is, I think we have a reasonable argument for more secure space. More on this later.

(2) Entomologists are excited about ethics

In another poster we provided a new version of the Insect Collectors’ Code (calling it an “oath” made it less approachable, according to one ECNer) and solicited feedback from the ESA attendees. People seemed to be quite enthusiastic about this project! We provided copies of the Code as small booklets (PocketMods; DOI: 10.6084/m9.figshare.5613052.v1), and they went like hotcakes. Yay! We have a manuscript in the queue to be published at American Entomologist and are contemplating a second one that goes into more depth on each issue. Stay tuned.

(3) November is a bad time of year for my health

Seriously! For the second ESA trip in a row I was ill. In 2015 is was some epic cough/throat ailment, and this year it was the worst eye infection I’ve ever had. This is pretty much how I looked at the meeting, with massively bloodshot eyes:

Fish, staring at the camera and having an eye phenotype that mirrors the post author's. The eyes of the fish are normal for that species, but in a human they would seem itchy and quite irritated!

Discus with red eyes and blotchy red pattern on body. Photo (CC BY-NC 2.0) by Wee Sen Goh. See original at https://flic.kr/p/7EeacC

There was no end of accusations that I was under the influence of a certain narcotic plant that is readily available in Denver. Sigh.

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Important Figures in the History of Natural History: Linnaeus

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

Carl Linnaeus was interested in botany from a young age. Both of his parents encouraged this passion, and would even give him flowers to cheer him up if he was upset. His father was both a gardener and a botanist and taught him the names of different plants, but Linnaeus often had a difficult time remembering the lengthy Latin names.

“Linnaeus in his Lapland Dress”. Image from Biodiversity Heritage Library (CC BY 2.0). Click for source.

As Linnaeus got older he decided to pursue a medical degree, since this was required to become a botanist at the time. He made many observations of the plants and animals in his homeland, but in describing species, he was still frustrated by the unwieldiness of lengthy species names. Linnaeus was a very practical person, and looked to create a standard method of naming and classifying organisms. His solution was to create the system of binomial nomenclature, which he introduced in a work titled Species Plantarum. This is regarded as his greatest contribution to science; his system of naming species is still used by taxonomists today.

Linnaeus’ most famous work is his Systema Naturae, in which he distinguished between three main groups: plants, animals and minerals. The first edition of Systema Naturae was published in 1735 and was very short, but each successive edition increased dramatically. The tenth edition, published in 1758, includes descriptions for over 6000 animal species and 4000 plant species. It is this edition that is considered as the starting point of zoological nomenclature.

Another important work from Linnaeus is The Economy of Nature. Though the work contains original ideas from Linnaeus, the text itself was likely written up by one of his students as a summary of his lectures. In The Economy of Nature, Linnaeus discusses the origin of species. His belief was that there was a single mountain, and that all species were created at the top of the mountain by God. Then, as the species came down the mountain and inhabited other areas, they began to diversify into varieties. Thus, while Linnaeus was a creationist, he believed that variations were not created directly by God at the first creation event but afterwards. This is an idea that influenced Darwin in the studies which culminated in the Origin of Species.

Special thanks to Emily Sandall for teaching me about the early life of Linnaeus!

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A New Publication in the Deans Lab: “Translucent cuticle and setiferous patches in Megaspilidae (Hymenoptera: Ceraphronoidea)”

All wasps in the superfamily Ceraphronoidea have pairs of translucent patches on the metasoma—two on the top and two on the bottom. The translucent patches on the bottom are also flanked by rows of bristles. But what are these structures for, and why are they important?

The translucent patches (stp) and setiferous patches (smp) in two different species of Conostigmus. A Conostigmus sp. C7A (identifier: CLEV 22741) B Conostigmus sp. C7B (identifier: PSUC_FEM 83781). The species notations given are not issued for purposes of zoological nomenclature, and are not published within the meaning of the International Code of Zoological Nomenclature. These images represent an early version of a figure created for publication. The final version of this figure was published in the Journal of Hymenoptera Research and can be viewed in the paper cited below. Photo by Carolyn Trietsch (CC BY 2.0). Click for source.

Ceraphronoidea are some of the most common parasitoid wasps in the world, but their lack of distinguishing features between species and small size (think sesame seeds and smaller) make them difficult to study. However, we noticed that the sizes and shapes of the translucent patches and the rows of bristles accompanying them were specific to each species, making it possible to distinguish between them.

So why are these patches different in different species? It could be related to their functions, but these were never investigated until now. In our study, titled “Translucent cuticle and setiferous patches in Megaspilidae (Hymenoptera: Ceraphronoidea)”, we used state-of-the-art techniques like serial block-face scanning electron microscopy (SBFSEM) to build three-dimensional models of the patches and corresponding internal structures.

Through this work, we showed that there are glands underneath the patches of bristles—the bristles probably increase the surface area for the evaporation of gland products. The substances secrete by these glands are probably for chemical communication (for example, producing pheromones related to courtship).

We’re still not sure what the function of the translucent cuticle is, but we did find unique cells called lamellar bodies underneath them. These cells are sometimes associated with glands, but they can also be associated with photoreceptors. It’s possible that light could shine through the patches and activate photoreceptors in the body that regulate circadian rhythms.

We looked to see if there were translucent patches of cuticle in other groups of wasps, and  found similar structures in Orussidae and Ichneumonoidea. Since the relationships between different groups of wasps are still unclear, further studies on these patches could help uncover how different groups of wasps evolved.

Citation:

Trietsch C, Mikó I, Ulmer JM, Deans AR (2017) Translucent cuticle and setiferous patches in Megaspilidae (Hymenoptera, Ceraphronoidea). Journal of Hymenoptera Research 60: 135-156. https://doi.org/10.3897/jhr.60.13692

 

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.

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