An ant-mimic spider escapes ant attention by being nearly odorless

Meet Peckhamia, a charmingly ant-like jumping spider:

Peckhamia is a common ant-mimicking jumping spider in North America (photographed in Urbana, Illinois).

Peckhamia avoids being eaten by predators by appearing like an ant rather than a spider. This defense is two-fold. Ants aren’t as palatable as spiders to most general predators, and spider-specialized predators might not recognize Peckhamia as food.

For mimicry to work optimally, though, spiders must inhabit places with plenty of ants. Not the easiest task, since ants eat spiders. And because most ants have poor vision, the spider’s physical resemblance to ants isn’t much help.

So how does this ant mimic spider escape being attacking by ants?

A new paper by Divya Uma et al in PLoS One provides a partial answer: Peckhamia doesn’t smell like a jumping spider. It doesn’t smell like an ant, either, so it’s not a chemical ant mimic. In fact, Peckhamia doesn’t smell like much at all. Look at the results of Uma et al’s cuticular hydrocarbon assay:

Figure 5 from Uma et al 2013, showing that Peckhamia have lower amounts of cuticular hydrocarbons than both the ants they mimic, and non-mimic species of jumping spiders.

Cuticular hydrocarbons are chemicals that impart odor, and Peckhamia has rather low amounts of these. It’s a stealth spider!

The researchers also measured predation rates by spider-eating wasps on Peckhamia (lower than on related species), and rates of attack by ants (lower against mimic spiders than against non-nestmate ants). I’d have liked to see the next step of actually painting hydrocarbons on the mimics to gauge the ants’ reaction, but even without that experiment the odorlessness of Peckhamia is an intriguing observation.

[for more ant mimics, see my ant mimic photo gallery]

source: Uma D, Durkee C, Herzner G, Weiss M (2013) Double Deception: Ant-Mimicking Spiders Elude Both Visually- and Chemically-Oriented Predators. PLoS ONE 8(11): e79660. doi:10.1371/journal.pone.0079660

A mural on moth wings

Evo-devo biologist extraordinaire Antónia Monteiro is visiting campus this week, and she shared with us this photograph of a simply unbelievable Malaysian moth:

Macrocilix maia, Malaysia

Do you see the mural?

Mimicry is common in insects. Some adopt the cryptic appearance of sticks or leaves, some ape the stripes of stinging wasps, and some sport the colors of poisonous butterflies. There are caterpillars that look like bird droppings, and beetles that look like caterpillar frass. I’ve even seen a blister beetle that mimics a harvester ant running backward dragging a seed.

But Macrocilix maia is a first. It’s the only mimic insect I know that paints an entire scene. It looks like a watercolor. Two red-eyed muscomorph flies feed from fresh bird droppings, complete with light glinting off their wings. I’ve never seen anything like it!

The scant published research on the mural moth is systematic in nature, with nary a mention of the incredible mimicry. In fact, the photo-sharing site Flickr has outpaced any academic work: photographer Allan Lee reports in 2009 that the moth reinforces the imagery with a pungent odor. That’s the extent of our knowledge. Macrocilix maia is a Ph.D. project waiting to happen.

Friday Beetle Blogging: Scared of a Beetle’s Bottom?

By the end of the week we bug bloggers are so discombobulated we can’t keep straight what insects we’re supposed to be writing about.

As you know, I sometimes stray from ants and post the occasional Friday beetle. Now fly guy Morgan Jackson has taken up Friday Ant Blogging, and coleopterist Ted MacRae is taking advantage of Morgan’s wanderings to claim flies for the Beetles in the Bush blog. It’s a little blog triangle. Which you probably should just stay as far away from as possible, as all of us are outside our areas of expertise and might just be making stuff up.

So. Beetles.

Here’s one that deceives with its rear:

Trichiotinus sp. flower scarab

Trichiotinus is a scarab beetle with fake eyes colored into the exposed tip of its abdomen. It sits in flowers with its hind legs held in the same position as wasp forelegs, looking like it just might leap out and sting. Presumably the false face confers protection from predators who don’t check their prey carefully.

On finding this beetle at Allerton Park last weekend I recognized it immediately. Insect legend Tom Eisner included a photo of Trichiotinus in For Love of Insects, a volume I regard as perhaps the most engaging insect book ever written.

From above, would you ever guess this beetle has a butt-face?

Photo details:
Canon MP-E 65mm 1-5x macro lens on a Canon EOS 50D
ISO 100, f/13, 1/250 sec, diffuse twin flash

Not the ant I thought it was…

High on my to-do list in Ecuador was Pachycondyla villosa. This is a large, wasp-like predatory ant coated with fine golden hairs. After some looking, one morning I finally spotted a worker foraging in the understory at Jatun Sacha. I came in for a closer look:

Sphecotypus niger

Approaching within ten inches I realized something wasn’t right. Even though the animal moved just like P. villosa, and even though the sun glinted off its elongate body at just the right hue, the antennae were slightly…weird. (more…)

The Ant that Wasn’t (Aphantochilus rogersi)

Aphantochilus rogersi (left) with prey

The most astounding arthropod I found in Ecuador last month wasn’t an ant, believe it or not, although it looks just like one from a few feet away.

Aphantochilus is a crab spider slightly over a centimeter long.  The species isn’t exactly uncommon in the Neotropics- in fact, Aphantochilus has appeared previously on Myrmecos. Rather, it is spectacular for its color, size, shape, texture, and movement. Aphantochilus is a convincing stand-in for Cephalotes atratus, the giant turtle ant, and every time I see one lurking about the margins of a turtle ant trail I do a double take and gleefully pass the next half hour watching it work.

Last month’s encounter was the first time I had a camera handy. Thus, some photographs to share with you folks.

A quiet moment

Although it may seem that the spider uses its impressive camouflage to fool its prey, I am not convinced.

The vision of most ants is rather rudimentary, enough that I think it unlikely such remarkable visual mimicry would yield enough of a payoff to be worthwhile. Ants perceive their environment predominately in a chemical medium. Instead, I suspect the spider intends to fool other visual predators- birds, maybe- that would normally pass up acidic chitinous ants but would happily take a spider. For more detailed explorations of the topic, see here and here.

Which is the spider, and which is the ant?

photo details
Canon EF 100mm f/2.8 macro lens & 12mm extension tube on a Canon EOS 7D
ISO 200, f/16, 1/250 sec. Indirect strobe bounced off white paper