The Bug Geek

Insects. Doing Science. Other awesome, geeky stuff.

Category Archives: Coleoptera (Beetles)

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.

__________________________

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

Advertisements

Photo Friday – A horned beauty

I’m still not entirely sure how this little fellow caught my eye – he was resting on the rough bark of a maple tree, blending almost perfectly.

Maybe he sneezed, or something.

Either way, he’s probably one of my favorite finds of the summer, partially because it’s a “new-to-me” species, and partially because…well, just LOOK at him:

Bolitotherus cornutus (Forked fungus beetle) 1

Male Forked Fungus Beetle, Bolitotherus cornutus

Is that not one of the most adorable little faces you’ve ever seen? The little upturned “nose”! But the fancy adornments on the thorax of this male forked fungus beetle (Bolitotherus cornutus) are what makes him stand out from the crowd:

Bolitotherus cornutus (Forked fungus beetle) 4

These Darkling beetles (family Tenebrionidae) like to hang out on shelf fungi on maple and poplar trees, and are mostly active at night. Only the males sport these fuzzy-tufted “horns”. I have scoured the literature and can’t find a single conclusive answer for their purpose. I suspect they’re partially for fighting with or expressing superiority over other males, but the hairs suggest some kind of sensory function. I really don’t know, and would love it if anyone could shed some light on these structures.

Bolitotherus cornutus (Forked fungus beetle) 3

__________________________________________

An another note, I just wanted to tell you that I’m on the Entomology conference circuit for the next two weeks! I’ll be attending and speaking at the Entomological Society of Canada and the Entomological Society of America meetings. If any of you are coming, I’d love to know! Send me a tweet at @GeekInQuestion 🙂 (Also, once these talks are finished, I’m going to FINALLY get around to updating you all on my research a bit – it’s been a productive couple of months!)

BugShot 2012 – Top Five Tips from the pros

Early this morning, the sun was peeking over the horizon, casting a soft, rosy glow on the morning mist and illuminating the spanish moss hanging from the trees in the vast oak scrub of this region. I went to bed waaaaaay too late after running around  for hours in the dark, catching and photographing bugs (GIANT ANGRY BITEY LONGHORNS), snakes (BABY CORN SNAKE), spiders (WOLF SPIDER THE SIZE OF MY HEAD) and scorpions (HOLY CRAP THEY GLOW UNDER UV LIGHT). I am running on zero sleep, but it is so awesome here and the day holds so much promise, I can’t be grumpy about it.

Extraordinarily p-o’ed Cerambycid beetle, intent on gnawing my fingers off. Thanks to Lee for angry-beetle-wrangling (this was not a one-person job).

The BugShot participants rolled into the Archbold Biological Station yesterday evening. After getting settled in and enjoying a great dinner, we were treated to the instructors’ “Top Five Tips” for macro photography.  I thought this would be a great way to start off my series of posts from this incredible workshop!
John Abbott:

  1. Tripod, tripod, tripod. Stabilization is a relatively inexpensive way to greatly improve the quality of your photographs.
  2. Try 400 ISO and natural light. With today’s cameras, noise is not such a significant factor.
  3. Use don’t be afraid to use autofocus, rather than manual focus.  Use your settings to focus on the bug’s eye.
  4. Know your equipment – learn the different features available to you and experiment.
  5. Set your custom white balance using a gray card. It will save you post-processing time.

Thomas Shahan:

  1. If you post your images online, tag your images with a location – this will help you get an ID and is also more scientifically useful.
  2. Be persistent. Take tons of pictures, and don’t worry if your keep:toss ratio is really low. Better to keep at it and get one or two really spectacular keepers.
  3. Lighting is important. Aim for soft, well-diffused light for more aesthetically pleasing results. You don’t want light to be a distracting feature in the photograph.
  4. Use the surroundings to enhance your subject. Think about using complimentary colours and  colour temperatures in your subject and background.  temps of the background vs the subject).
  5. Sometimes it’s best to make your own equipment – it is usually inexpensive, can be adapted to your particular needs, and the results are often more desirable. Also, there’s something to be said for struggling to create beautiful art.

Alex Wild:

  1. Know your subject: tell a story with the photo, think about the natural history of your subject. This is where entomologists have an advantage.
  2. Simplify: keep the photo simpler than real life. Too much “stuff” going on in the image (e.g., background distractions) can detract from the image.
  3. Understand lighting. Think about the colour, quality, direction, intensity of light when framing a photo.
  4. Know your equipment and have a comfort zone with certain default settings. Have fun experimenting but have a reliable fall-back you can use if you need to get that ONE photo RIGHT NOW.
  5. Use your equipment for the photographic purpose for which it was designed (don’t use a screwdriver as a pry bar). Different cameras have different strengths – they’ll all take beautiful pictures, but not the same KIND of pictures.

Next up: Maxing out your magnification, with Thomas Shahan.

BugShot 2012!

I am one excited geek right now: in just a few days, I’ll be hopping on a plane and heading down to the Archbald Biological Station in Venus, Florida where I will join about 35 other people who are taking part in the premiere insect macrophotography workshop of the year: BugShot 2012!**

Whitebanded crab spider, Misumenoides formosipes, snacking on a Sphecid wasp

Three days of workshops, hands-on gear demonstrations, and opportunities to practice in the field and in studio-style settings await me! I am super-pumped and plan to suck up every last drop of knowledge I can manage, not only from the incomparable instructors (Alex Wild, Thomas Shahan and John Abbott) but also from the other participants.

Fishfly, Chauliodes sp.I wanted to take this opportunity to thank all the people who either purchased something from my store or sent in a donation so that I could attend. I never would have managed this trip without your incredible generosity: all together, you helped me raise nearly $800 – enough to cover the registration fee and a chunk of the travel expenses!

Female horse fly 1

I am humbled, touched, and honoured that so many of you reached out to me.  I will, as promised, be blogging and tweeting the event, to share some tips and tricks with all of you. Hopefully I’ll also get a stash of some great photos of Floridian fauna to get me through the winter!

Ironweed Curculio (Rhodobaenus tredecimpunctatus)

___________________________________________

** The photos used in this post are some that I took at the inaugural BugShot workshop in 2011 and haven’t been featured on the blog yet 🙂 The two taken in a “white box” represent my first attempts at this technique, and at using a flash – two great things I learned last year. With a year of practice under my belt, I know I’m going to take away so much more this time around!

Photo Friday: Beetles. With worms.

Yes, I was ignoring my blog this week.

I am working on a new project that developed when some really interesting samples came up from one of our sites in the Northwest Territories – beetles parasitized with hairworms. I’ve posted about these before, but this site is special because there are SO FREAKING MANY OF THEM. It’s crazy. I have a new collaborator in the U.S. who is going to ID the worms for me, and I’ve been working my tail off to get all the hosts ID’d.

Since I’m totally obsessed right now, I thought I’d share my obsession:

Anyone who follows my Twitter or facebook accounts is probably sick to death of hearing about beetles with worms.

I’m sorry.

I promise I’ll try to talk about something other than squiggly things creeping out of beetle’s butts next week, ok?

%d bloggers like this: