And now, a spider

I do apologize for the lack of blogging this week- I’ve been busy with lab work. Until things free up, here’s a spider:

Neoscona sp. barn spider

She set up shop across our back stairs at the perfect height to snare a human. Ambitious!

I took this photo for the forensics folks in case we go missing.

Monday Night Mystery

Tonight’s challenge: identify this adorable little beetle.

Points will be awarded to the first commentators to name the family (3 pts), genus (3 pts), and species (3 pts). Plus, two more points if you can tell me where I collected it. This species has a rather unusual habitat.

The cumulative points winner for the month of September will win their choice of 1) any 8×10-sized print from my photo galleries, or 2) a guest post here at Myrmecos on a safe-for-work topic of their choosing.

Linepithema on the Tree of Life

One of my projects at the moment is coordinating beetle pages for the Tree of Life site. But I’ve been sneaking some ant work in on the side, with a trimmed-down version of my Ph.D. dissertation published this morning:

Linepithema on the Tree of Life

Participating in the Tree of Life isn’t hard. If you have taxonomic expertise and would like to help out, or just have photos, videos, or other natural history media, I highly recommend contributing.

The Battle for Clinton Lake

Two pavement ant colonies fight for territory along the shores of Clinton Lake, Illinois.

Even the most epic moments of ant warfare can seem inconspicuous from the towering height of our human eyes. The fisherman above, for instance, didn’t even flinch at the hostilities at his feet, even after I pointed out the boiling mass of angry ants. “Someone must’ve spilled something there,” he grunted as he moved on.

But nothing was spilled. This was a territorial boundary between two large colonies of Tetramorium pavement ants. I happened across it while hiking along the shores of Clinton Lake last week, just in time to watch the ants’ numbers escalate along the front. Both colonies were pouring all their fighting-age workers into the fray, hoping to push the borders back and claim a larger swath of prime lakeside real estate.

Granted, from six feet up pavement ants don’t look like much: (more…)

Answer to the Monday Night Mystery

Schizura ipomoeae (Notodontidae)

Last night’s mysterious moth larva played right into the hands of lepidoptera expert Chris Grinter, who swept all 10 points less than 8 minutes after the post went up:

Notodontidae cats tend to have this broken/jagged leaf appearance – they cut little circles out of the leaves and then sit in them to match the leaf edge. Also, the green band and the two large humps on the back make this stand out in the Schizura. It might appear to be S. unicornis, however that species lacks the distinct humps that this species does. Form Wagner “similar to S. unicornis, but with A5 distinctly humped”.

Over on Facebook, parasitoid biologist Josephine Rodriguez wryly noted that the mystery insect was merely “microgastrine food”. True enough. Two additional points to Josephine for thinking outside the box.

Mutualisms are more complex than they appear

The African Ant-Acacia system continues to yield valuable ecological insight. PNAS published another excellent paper yesterday by Todd Palmer’s group that combines modeling with empirical data to show how short-term evaluations of mutualisms miss key dynamics:

[excerpted from the abstract] The tropical tree Acacia drepanolobium associates with four symbiotic ant species whose short-term individual effects range from mutualistic to parasitic. Using a long-term dataset, we show that tree fitness is enhanced by partnering sequentially with sets of different ant symbionts over the ontogeny of a tree. These sets include a “sterilization parasite” that prevents reproduction and another that reduces tree survivorship. Trees associating with partner sets that include these “parasites” enhance lifetime fitness by trading off survivorship and fecundity at different life stages. Our results demonstrate the importance of evaluating mutualism within a community context and suggest that lifespan inequalities among mutualists may help cooperation persist in the face of exploitation.

Plants have different needs as they age, with young ones prioritizing growth while older ones favor reproduction. As their four ant symbionts differ in how they affect plant growth versus reproduction, trees that host all four ant partners as they pass through life are more successful than those that are more static in their partnerships.

The most striking finding is that ant species previously thought parasitic for their tendency to temporarily sterilize the host plants actually benefit the system when the 100+ year lifespan of the tree is considered. These supposed parasites favor early growth so that larger, healthier trees are better able to reproduce once they switch over to a non-sterilizing partner. It’s a striking example of nature’s subtlety, and not the only recent reminder that “cheaters” aren’t always what they seem to be.

More coverage at Not Exactly Rocket Science.

source: Palmer, T. M. et al. 2010. Synergy of multiple partners, including freeloaders, increases host fitness in a multispecies mutualism. PNAS online early 10.1073/pnas.1006872107

Monday Night Mystery: Pretending to be half-dead

Tonight’s challenge is a straight-up identification:

This caterpillar hides from predators by pretending to be a dead leaf, except for the bit that’s faking a living leaf. It was photographed last week on an oak tree here in Central Illinois.

Points will be awarded to the first person to guess the:

1. Family (4 pts)
2. Genus (3 pts)
3. Species (3 pts)

Remember that supporting information about identifying characteristics must be provided to get full credit.

As usual, the cumulative points winner for the month of September will win their choice of 1) any 8×10-sized print from my photo galleries, or 2) a guest post here at Myrmecos on a safe-for-work topic of their choosing.

The death of an ant

I couldn’t resist photographing this morbid scene of an ant’s body suspended in a spider web. The eerie shape in the background is just the out-of-focus bark of a sycamore tree. I didn’t plan it that way, but the shadow certainly adds to the tone.

photo details:
Canon EOS 7d camera
Canon MP-E 65mm 1-5x macro lens
ISO 100, f/13, 1/250 sec
diffused twin flash