The Bug Geek

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Category Archives: Research Blogging

Poop, not parasites

So a very cool bug photo has been circulating on the web: I’ve seen it on Tumblr, Facebook, Pinterest and Twitter. It’s a pretty darn great photo:

Photo of a Cereal Leaf Beetle Larva, by Giles San Martin, used under a Creative Commons License.

Photo of a Cereal Leaf Beetle Larva, by Giles San Martin, used under a Creative Commons License.

Let’s zoom in on that a little, shall we?

Closeup

Well, my goodness. That’s really something, isn’t it? Here’s the accompanying story circulating on the web:

This is a juvenile form of the Cereal leaf beetle (Oulema melanopus) after being parasitized by Tetrastichus julis, a parasitoid wasp which lays its eggs inside the larva of the beetle. They eggs hatch within the larvae and begin to feed while it is still alive, before they burst out and kill it.These parasites are often used as a biological control, as the Cereal leaf beetle is considered a pest and regularly feeds on crops.

Well, now, that is REALLY something isn’t it? Parasites are so freaking cool.

The problem is, the pairing of this particular image with this particular caption has lead to some confusion. 

While the species identities are correct, and the stated relationship between the two is correct, the caption seems to imply that the skin of the poor beetle larva is stretched shiny-tight and close to bursting from a insanely huge parasite load (indeed, this is how the interwebz has been interpreting it).

This interpretation is only a little bit correct.

The beetle IS parasitized – by one parasite. Just one. 

The rest of that squirmy-looking mass on the back of the beetle is a perfectly normal thing (well, if you’re a leaf beetle anyways): it’s a fecal shield. Yes, fecal shield. As in, “poop”.

Many, many Chrysomelids (leaf beetles) create fecal shields, depositing their feces on their backs. It’s so prevalent, in fact, that the study of fecal shields warrants its own term, apparently. From the section in Caroline Chaboo’s book chapter on Chrysomelid defences entitled, “Fececology” (ha!):

The [Chrysomelid] subfamily Cassidinae has ~3,000 species whose larvae carry a mobile shield made of dried feces, attached to paired processes at their hind end, and held over the body like an umbrella. This shield may be held flat on the dorsum or elevated to hit an attacker. In two other leaf beetle subgroups, the subfamily Criocerinae (~1,400 species) and in some members of the subfamily Galerucinae (~14,000 species) the fecal material is simply piled directly onto the back of the animals, with some falling off as the animal moves around but regularly replenished to maintain coverage of the exposed dorsal surface (Fig. 2b, c). In Chrysomelinae leaf beetles (~4,000 species), the mothers take time to build a fecal case entirely around every single egg.

Compare the photo above with this one showing the fecal shield of a Criocerine Chrysomelid, Lilioceris lilii:

Photo by Luis Sanchez, used under a Creative Commons License.

Photo by Luis Sanchez, used under a Creative Commons License.

Also goey, revolting, and arguably very unsanitary – but normal.

Here’s a different spin on the same theme, this time in a tortoise beetle larva (Cassidinae):

_MG_9225

Photo by Kurt Komoda, on Flickr: http://www.flickr.com/photos/komoda/ Used under a Creative Commons License.

Less slimy, and mobile – but normal. (And still poop).

Fecal shields provide camouflage, prevent desiccation (drying out), and, ironically, can deter predators and parasitoids. Some parasitoids, however, can exploit the fecal sheild and may actually be attracted to the plant volatiles (smelly plant chemicals) in the feces. This could be what happens in the relationship shown in the photo, since the T. julis is a well-established predator of the cereal leaf beetle and, obviously, that goey shield is not much of a deterrent.

So, just to clarify what you’re seeing in the original ZOMGPARASITES photo: in addition to piles of poop, the one visible parasitoid larva is the pale, segmented critter in the front near the beetle larva’s head. Now, its placement is a little odd, because T. julis is normally an endoparasitoid, meaning that the mother wasp lays her egg(s) directly inside the body of the host (the beetle larva). In this case, though, it looks like the parasitoid larva is floating in the fecal shield, so I’m not sure what that’s all about. Lousy aim, perhaps? Even if it was a motherly misfire, I have it on good authority (hat tip to Richard Comont) that the photographer reared out the parasitoid and it did indeed grow up to be T. julis.

So. Long story short:

This is a normal fecal shield, people. Not an imminent explosion.

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ResearchBlogging.org

Chaboo, Caroline (2011). Defensive Behaviors in Leaf Beetles: From the Unusual to the Weird in Chemical Biology of the Tropics, J.M. Vivanco and T. Weir (eds.), 59-69 DOI: 10.1007/978-3-642-19080-3_4

Evans, E., Karren, J., & Israelsen, C. (2006). Interactions Over Time Between Cereal Leaf Beetle (Coleoptera: Chrysomelidae) and Larval Parasitoid Tetrastichus julis (Hymenoptera: Eulophidae) in Utah Journal of Economic Entomology, 99 (6), 1967-1973 DOI: 10.1603/0022-0493-99.6.1967

Schaffner, U., & Müller, C. (2001). Exploitation of the Fecal Shield of the Lily Leaf Beetle, Lilioceris lilii (Coleoptera: Chrysomelidae), by the Specialist Parasitoid Lemophagus pulcher (Hymenoptera: Ichneumonidae) Journal of Insect Behavior, 14 (6), 739-757 DOI: 10.1023/A:1013085316606

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A fungus ate this moth’s head

It’s been far too long since we’ve had a good gross-out parasite post, so let’s rectify the situation, shall we?

I captured this gruesome scene at the end of June, in the park where I was camping.

This poor unidentifiable moth met a horrifying end in the grips of an entomophathogenic fungus, which, though technically not a parasite, is nevertheless growing gangbusters out of the moth’s head.

While non-pathogenic fungi use less gory approaches to dispersal and propogation, relying on things like wind and water, entomopathogenic (EP) (entomo=insect; pathogenic=disease-causing) fungi use insects and other arthropods as their food source and means of spore transmission.

EP fungi produce spores that attach to, sprout on, and penetrate the outer shell (or cuticle) of their host.  Once they’ve breached the outer barrier, they feed on the nutrients available inside the host, ultimately killing them. What you see in the photo above is the final stage – the host has been killed, and the fungus has produced mature fruiting bodies from which more spores will be produced.

One of the most fascinating aspects of these fungi is their ability to alter their hosts’ behaviours – sometimes in ways that maximize the likelihood of spore dispersal, and sometimes in ways that actually harm the fungus and help the host fight off the infection – there seems to be a finely tuned evolutionary tradeoff at play in these systems that permits both the fungus and the host to persist and thrive despite the unpleasantness of the interaction between them.

For example, a fungal infection may lead a host to seek out sunlight or other sources of heat; by raising their body temperature (a so-called “behavioural fever”), the host can sometimes make its body inhospitably warm for the invader. Other EP fungal infections, such as those seen in pea aphids, can cause an infected aphid to move to unusual, more exposed parts of the plant to feed. This could be the fungus’ way of ensuring better spore dispersal, or might be the aphid’s way of preventing the fungus from spreading to the rest of its colony. Some fungi seem to make female hosts more attractive to males (presumably to aid in spore transmission), while others cause hosts to seek out elevated sites before their deaths (as was most likely what happened to this moth).

This is all terribly reminiscent of the mind-controlling hairworm I posted about last year, and behavioural changes have also been shown to be induced by insect parasitoids; it’s clear that behaviour modification is a useful strategy for many organisms that rely on a host to complete their life cycle!
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ResearchBlogging.org

Roy HE, Steinkraus DC, Eilenberg J, Hajek AE, & Pell JK (2006). Bizarre interactions and endgames: entomopathogenic fungi and their arthropod hosts. Annual review of entomology, 51, 331-57 PMID: 16332215

Grosman AH, Janssen A, de Brito EF, Cordeiro EG, Colares F, Fonseca JO, Lima ER, Pallini A, & Sabelis MW (2008). Parasitoid increases survival of its pupae by inducing hosts to fight predators. PloS one, 3 (6) PMID: 18523578

Why I spend so much time on the internet (#ScienceShare)

Internet Forever! (Image from: Allie Brosh at www.hyperboleandahalf.blogspot.com) )

Internet Forever! (Image from: A. Brosh http://www.hyperboleandahalf.blogspot.com)

During the course of an average day, when I’m working on any number of academic pursuits from my home office, I visit a bunch of web sites: library data bases, insect identification aids, online scientific journals, statistical software help pages, how-to lab/procedural pages, etc.

I also spend time on Facebook, Google+, Twitter, Flickr and a big ol’ pile of blogs.

I’ve been thinking about the title of a talk I’d like to give. It would sound something like, “Why I spend so much time on the internet.” Lately, I’ve had a number of very interesting discussions with other grad students, faculty members, and online sciencey-folks about the roles and effects of social media on the way we think about science, do science, and communicate about science.

Let me be frank: I’m really, really excited by the buzz about the topic (Morgan Jackson provides a great round-up of blog posts at his blog Biodiversity in Focus ), not only in different social media venues, but also in more traditional, academic forums.

A recent paper in the journal of Innovative Higher Education by D. Powell, C. Jacob and B. Chapman provides strong arguments for the benefits to academics of blogging and other social media, with implications for research, teaching and learning, and outreach. I get the sense that academics can more intuitively appreciate how social media can be used in outreach activities, and even in teaching, but many are still very resistant to the notion of incorporating social media in their research activities.

Here are some reasons why scientists should embrace social media:

  • Social media can be used to identify research opportunities and find collaborators.
  • You can get real-time feedback from other researchers, helping you refine your research questions, methods, and interpretation of experimental results, well before the formal publication stage.
  • You can easily get this feedback from a larger, more geographically and disciplinarily diverse base of expertise than you would likely reach via traditional means.
  • From a more altruistic perspective, other researchers can benefit from online transparency and accessibility, often in ways that cannot happen in traditional media. For example, lab methods or data collection instruments can be demonstrated in photographs or video (saving other researchers the trouble of trying to decipher complex methods sections if they’re interested in replicating specific protocols in their own work).
  • Blogging can help you become a better communicator, by improving writing skills and language proficiency.
  • Sometimes journalists get it wrong. You can tell the public about your research in your own words.
  • Blogs, by their very nature, permit the rapid distribution of information to a very wide public audience. Your new paper will get more attention and readership if it gets cross-posted on multiple blogs and Twitter than if it only gets delivered to paying subscribers of a particular journal.
  • You can access alternative modes of funding for your research.
  • It is fun; also personally and intellectually rewarding.
  • Soon, everybody will be doing it: get with the program.

I’m being a little tongue-in-cheek, but I mean it in all seriousness. I will even go so far as to say that scientists must embrace these new tools. I think that social media are going to be the catalysts for a major paradigm shift in the scientific community, in terms of who we perceive as being the audience/receptors of science and who we perceive as being our collaborators.

P.Z. Meyers at Pharyngula cautions researchers not to be dismissive about the role of blogging/blogs in scientific discourse, and highlights the need to develop the pertinent skills:

I can imagine a day when this kind of presentation [blogging about a new study] becomes de rigueur for everything you publish, just as it’s now understood that you could give a talk on a paper. It’s a different skill set, too, and it’s going to require a different kind of talent to be able to address fellow scientists, the lay public, and science journalists. Those are important skills to have, and this kind of thing could end up making them better appreciated in the science community.

Boraz Zivkovic at Scientific American’s A Blog Around the Clock discusses the evolution and future of this paradigm shift in his post, “The scientific paper: the past, present and probable future” more eloquently than I ever could; please take some time to read the entire post.

This evolution will not happen overnight. There is still considerable resistance to the notion that blogs and other new media might have a role in “real” science.

Take, for example, this comment left on the Tree of Life blog (Jonathan Eisen, UC Davis evolutionary biologist), by the author of a paper that was critiqued by both the blog author and commenters:

I would like to provide my response to several comments that have been mentioned here that will not arise in a peer-review setting and that make blogs a dangerous venue for information delivery as it reduces the credibility of findings regardless of scientific support [emphasis mine].

To which I say: “Really? Reeeaaallly?” Blaming the medium for the message (which could have easily been shared between professors in a lunch room, by grad students participating in a journal club discussion, or by a dissenting colleague in a conference talk) is, frankly, asinine.

Blogs encourage discussion, the sharing of ideas, and open debate. We may not always agree with or appreciate what is said (especially if someone is criticizing our own work), but that’s life. Sometimes statements may be made that are not based on factual information, but you can bet your bippy that if misinformation is published (either in the form of a comment or a post) readers will be quick to point it out. Edits or retractions can happen immediately, and we don’t have to wait for the next issue of X journal to come out to hear other opinions or see corrections made.

What is unique, and arguably better, about blogs compared to more traditional discussion venues is that blogs allow real-time discussion in a public forum. To quote Powell et al.:

Conversations about scholarly work that in the past have been restricted to faculty hallways, conferences…publications and response in subscription-based journals are now also occurring in openly accessible online spaces, opening up the dialogues to a broader audience…

Said another way, social media is just another kind of “hallway talk…in a really, really, long hallway”. (Thank you Bug Girl  for that most excellent insight.)

I think nay-sayers need to understand that no one is suggesting that we do away with traditional means of publication (journals, books, conference proceedings, etc.). Rather, social media should be embraced as a compliment to these traditional communication tools.

There are, of course, some kinks to iron out. There are issues of copyright, intellectual ownership, co-authorship, and the risk of being “scooped” by other researchers (although, regarding that last point, read this: “On getting scooped in ecology“). Although Powell et al. mention some of these concerns, no suggestions for addressing them are offered.  While these factors certainly present challenges, surely they are not insurmountable; it simply speaks to the need for additional discourse and the establishment of standards for these new media forms.

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ResearchBlogging.org

Douglas A. Powell, Casey J. Jacob, & Benjamin J. Chapman (2011). Using blogs and new media in academic practice: potential roles in research, teaching, learning and extension Innovative Higher Education

Mind-controlling beetle parasite

This post was chosen as an Editor's Selection for ResearchBlogging.org

I’m sorting through beetle specimens collected from Iqaluit, Nunavut today.

There’s not a ton of diversity in the samples so far, and I was starting to get a little bored, until I saw this:

beetleworm3_sm

Say it with me now: “EWWWWWWWWWW“.

Now say, “COOL!”

Very good.

This poor ground beetle (family Carabidae) has been parasitized by a nematode-like worm called a hairworm, or “Gordian worm”, (Gordiaceae: Nematomorpha).  Adult hairworms are free-swimming, water-dwelling animals (either in fresh or salt water). They mate and produce young (larvae) in the water.  The larvae require two hosts. First they infest various small arthropods (called paratenic hosts), like mosquito larvae. Next, those small paratenic hosts are consumed by other, larger arthropods – ground beetles fit the bill since they are heavy-bodied, voracious predators.  Worldwide, at least 70 species of ground beetles are known to be hosts for hairworms.

When the worm is mature, it has to leave its host and return to the water to reproduce. If it has infested an aquatic insect, it has no trouble making its way back to the water. However, if it has chosen a terrestrial insect as a host, things get a little more complicated.

Like so many parasites, the hairworm can use a type of mind-control to affect the behaviour of its host. In this case, it compels the terrestrial beetle to seek out water, then drown itself. Yikes! For this beetle, which I caught in a yellow pan trap, I can envision one of two scenarios: 1) the worm was mature, and convinced the beetle to take a dip in the preservative fluid in the trap, or 2) the beetle just happened to wander into the trap, and the worm decided to abandon ship. Whatever happened, it was not a happy “ending” for either animal!

beetleworm4_sm

Not a happy ending.

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ResearchBlogging.org
Poinar G Jr, Rykken J, & LaBonte J (2004). Parachordodes tegonotus n. sp. (Gordioidea: Nematomorpha), a hairworm parasite of ground beetles (Carabidae: Coleoptera), with a summary of gordiid parasites of carabids. Systematic parasitology, 58 (2), 139-48 PMID: 15449829

I selected this post to be featured on my blog’s page at Nature Blogs.
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