The Bug Geek

Insects. Doing Science. Other awesome, geeky stuff.

Category Archives: Hymenoptera (Bees, Wasps, Ants)

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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Photo Friday: Wolf spider parasite

I’m busy preparing my talk for the Entomological Society of Canada conference*, which is coming up in just a few short weeks! I plan to give a presentation about the cool/gross beetle parasites I found in some of my Arctic study sites.

Since I’m once again (still?) parasite-obsessed but don’t want to bore you with more photos of worms coming out of beetle’s butts, here’s another cool parasite (well, parasitoid, technically) from the Yukon territory, photographed while driving up the Dempster Highway this summer.

Parasitic wasp emerging from the egg sac of a wolf spider

Wolf spiders are incredibly abundant predators on the tundra – you can see them scatter underfoot with every step. Females are even easier to spot, since they are often toting their pale-coloured egg sacs at the end of their abdomens.

Many of the spiders’ eggs will never hatch, however: somewhere along the line, a teeny-tiny parasitic wasp laid HER eggs beneath the carefully spun silk.  The baby wasps hatch and then feed on the spider’s offspring, and the end result is what you see up there: little wasps emerging from the poor mama spider’s egg sac.
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* Speaking of the ESC meeting, if you are attending and haven’t yet submitted your images to the Photo Contest, GET ON IT! It promises to be a great competition, with extra-cool judges like John Acorn !! Go submit now!

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)

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** 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!

Field season in the Yukon – part 2 (the fine art of collaboration)

Now that the “oooh, aaaah” part of my field work is out of the way, let’s talk a bit about doing research, shall we?

My PhD work is a component of a research program called the Northern Biodiversity Program. It involves several professors from several universities, about a dozen grad students, a postdoctoral researcher, and a multitude of private and public partners. The word that must best describe a project of this scope is: “collaborative”.

col·lab·o·rate intr.v. col·lab·o·rat·ed, col·lab·o·rat·ing, col·lab·o·rates

1.To work together, especially in a joint intellectual effort.

Although we all share the same overarching objective, our personal research goals and areas of specialization are quite different. On this trip to the Yukon, I traveled with: an arachnologist studying spider population genetics; a hymenopterist doing biodiversity inventories of wasps using molecular techniques; another arachnologist interested in the distribution and life history of a species of pseudoscorpion; and another hymenopterist working on parasitic wasps and their leaf-mining caterpillar prey. Me – I study beetles and am interested in functional ecology and food webs.

Our research questions essentially had zero overlap, with the exception of the locality: it’s what brought us together for this particular field trip. In a nutshell, it meant five different types of critters being targeted for collection using five completely different methods in five different habitat/terrain types.

Hm.

This is the kind of situation that has serious potential to turn a group of nice, sane, rational adults into cranky, snarly, whiny ass-pains. It’s true. I’ve seen it happen. It’s very easy to get all “ME ME ME” in the field, wanting nothing more than to spend all your time basking in the glow of your own beloved study subjects, and getting royally snarky over any time “wasted” on other people’s work.

Happily, this is not what happened on my trip. I have proof:

Happy campers, L-R: Barb (wasps), Katie (spiders), me (beetles), Laura (wasps and prey), Chris (pseudoscorpions). Photo by Chris Buddle.

The smiling faces you see there belong to a group of people who understand how to collaborate. We took turns, helped each other out when our own work was finished or on hold, made concessions, compromised. We chatted about research ideas, approaches, and troubleshot. It was awesome.

My beetle collection techniques are primarily “passive”: I stick traps in the ground them come back later to collect the contents. Since I had a lot of waiting time between setting and collection (which everybody helped me do), I thoroughly enjoyed myself working with the others.

Yellow pan trap, with contents after a few days

We helped Katie catch wolf spiders by marching over the tundra and scooping them into a cupped hand or net as they scurried out from underfoot.

Laura and Chris help Katie search for wolf spiders

We picked caterpillars out of the “umbrella of science” after Laura whacked the bejeezus out of willow tree branches, catching critters as they fell into the umbrella held below.

Katie, Laura and Chris pick caterpillars out of Laura’s “umbrella of science”

We turned over hundred of rocks along creeks and found lovely little pseudoscorpions, helped Barb set up and take down her wasp traps, and I took photos of some of my teammate’s fascinating finds (always handy for papers or talks!).

A jumping spider – species yet to be determined!

One of Laura’s leaf-mining caterpillars (left), killed by a parasitic wasp larva (right). Two eggs laid (can you spot them?) indicate hyperparasitism.

Our willingness to collaborate made the trip enjoyable, the work smooth, and the inevitable challenges of field work less challenging. Although academic research seems to be an inherently competitive business most of the time, the benefits of working with others effectively and collegially make the extra effort, patience and open-mindedness very worthwhile.

Hey Geek, what’s this? An ant that’s not…

This mystery was passed on to me from a friend in Texas, who fields the “what’s this bug?”-type inquiries that are sent to his place of employment.  The email subject line was: “Challenging ID“, and this message and lovely photograph from Kimberley were attached:

I was hoping you could help me identify what type of ant this is. I have seen a few on the black eyed peas in my garden, they are always alone. I would estimate they are about 1/2 inch long, maybe a little bigger

Photo by Kimberly Hill

Now, my friend already knew the answer. “Here is a tough one,” he said. I considered this to be a fun little test from my respected colleague, so I was all,

The first thing I found myself doing was counting “stuff” at the head end of this critter. I was reminded of the time we took our three-legged dog to a friend’s bbq, and caught another guest staring at our pooch from across the yard with a perplexed look on her face, saying aloud, “Oooone….twooooo…three.  One…two…three?”

Similarly, I count three dangly bits hanging off this insect’s face – two antennae and … a proboscis. Last time I checked, ants did not have sucking mouthparts,

Impostor!

This is not an ant at all; the mouthparts are a dead giveaway for something in the Hemiptera. Since it doesn’t have fully developed wings, it must be a juvenile, or nymph.

Putting all the pieces together:

  • ant mimic
  • pretty distinctive colouration and shape
  • true bug
  • nymph
  • found on a legume plant
  • a Texas locality

I’ve been able to come up with what I think is a pretty good guess of this critter’s identity:

the Texas Bow-legged Bug (Hyalymenus tarsatus).

This insect looks remarkably different as a juvenile than as an adult (see some images here) and the juveniles show a wonderful range of coloration. The only species in the genus found in Texas, these insects are known to feed on legumes and other plants with seed pods, like milkweeds.

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