Today PLOS came out with a special issue highlighting papers that describe the many effects of climate change on living things. There is a lot of interesting work in there, and I’m happy we had the opportunity to rep. scale insects alongside the birds and the coral reefs.
It’s been a while since I’ve felt like writing anything, mostly because I’ve spent my time wrapped up in thoughts about who eats whom, who stings whom and lays an egg inside whom and when. I wake up in the morning and brush my teeth to these thoughts, and sometimes I even wake up in the middle of the night to some weird dream my brain has put together about the stinging, the egg laying, and the when. Mostly I think about the parts of my project that haven’t quite gotten figured out yet. This, I’ve decided, is a lot of fun. I make graphs, I tinker with ideas, most of which don’t work out the way I hope. But whatever is actually going on is almost always cooler than what I hope. Then I go outside and have ice cream with my friends, and while they’re talking, I make an effort to stop thinking about the stinging, the egg laying, and the when, though sometimes I realize I’ve failed when I re-enter conversations in the middle of their sentences. Thank goodness this phase only lasts so long.
Andrew Ernst, a taxonomist in our lab that can tell the difference between very small insects, takes photos like these that I look at every now and then to remind myself that the graphs I’m making, the thoughts I’m thinking, and the dreams I’m dreaming are about real creatures that are so lovely, yet so tiny (a few millimeters at the most) that we never see them. The parasitoids are everywhere, and without photos like these they are nowhere to us huge animals.
Parasitoids are wasps. They sting their hosts (insects, spiders, etc) and lay eggs inside them. The eggs develop into larvae that eat the host from the inside out. It’s a zombie situation. All of the parasitoids here attack pesty scale insects. They’re the good guys.
And now I’ll go back to thinking about them–as if I ever stopped.
Hurray for fun tropical adventures on our day off in Panama! A few days ago, we traveled to the Smithsonian Canopy Crane.
The crane your run-of-the-mill construction crane with a gondola attached. We all thought we were going to be afraid, but being in the canopy is a lot like being on the ground except that there are animals that hang out in the tree tops, like these!
Azteca ants in their carton nest
We also saw a three-toed sloth, white-shouldered tanagers, and wasps and bees.
Researchers use this crane to learn what’s happening in the rainforest canopy. They can even talk to the crane operator and choose where to go. Most of the research in the canopy now is a mapping race: Who lives there? How much CO2 do different types of canopies absorb and give off? How do different types of trees defend themselves from plant-eating insects and mammals? Then, of course, there are the gliding ants: http://www.canopyants.com/video1.html
I’m leaving Panama in one day. I’ve learned a ton here, and the tropical behavioral ecology course (http://www.stri.si.edu/english/about_stri/headline_news/news/article.php?id=1664) has been by far one of my favorite experiences as a graduate student. Thanks to everyone who made it awesome, especially Rachelle Adams and Jon Shik.
When I was thinking about what to study in Panama, one of the course instructors suggested Azteca ants. I read about them, and their life history is so crazy it was hard to believe until I saw it.
Azteca live their entire lives inside these trees.
Azteca’s house trees called Cecropia have evolved to provide them with everything they need, including food. The Cecropia trees have soft tissue at the base of their stems that produces tiny round, white egg-like food capsules. The ants think they’re delicious.
Here are the Azteca and Cecropia in action: http://andy.dorkfort.com/andy/2012/12/ant-plants/
The trees have trained the Azteca: they give them a home, treats, and a favorable microclimate. In return, the Azteca guard their trees like an army. When I touch a leaf they come charging out of the tree in swarms. Lucky for me, they don’t hurt so bad, because they’ve bitten me everywhere imaginable.
The other day I dissected my first tree. I went outside, found a short tree, cut it into pieces, stuck it in the freezer, then took it to the microscope to see what was inside. The Cecropia trees are separated into internodes, and each internode is separated by spongy skin inside the plant. I found that in each internode, the ants do something different. In one internode, they raise their young, in others they store their garbage, tend their queen, and, my favorite, tend their mealy bugs!
Each internode is a diorama that tells the story of what was happening when I disrupted their colony (sorry, gals!) and brought them back to the lab.
Here they are, raising babies.
In this tree, something went wrong. All the Azteca were dead and covered in fungus, and the mealy bugs—the white, fuzzy bugs on the right—had been attacked by parasitoids.
I want to know everything about them. This mutualism is an evolutionary puzzle, and I suspect that the more we dig, the more we’ll find. So many mysteries are waiting to be figured out. For example:
1. There are piles of nematodes next to the Azteca babies. No one knows who puts them there or what they do.
2. We know almost nothing about third partner in this relationship: the mealy bugs, which provide the ants with sugary poop. In this video, the mealybugs look like pieces of white fuzz. I was delighted to find that the ants pick up their mealy bugs and move them to safety! I’ve noticed that when the ants are disturbed they bite their mealy bugs and drum them with their antennae. Mealy bugs have these long straw-like mouthparts that anchor them to their plants, and I think the ants drum and bite them to say, “Hey, time to pull your mouthparts out! Let’s go!”
3. The ants cover the bottom of the nodes that they occupy with an orangey brown mat. I don’t think anyone knows what it is or what it does.
4. And maybe the craziest thing I’m thinking about: The plant seems to digest the ants with the help of a fungus. Cecropia trees are known to absorb most of their nitrogen from the Azteca—which I THINK IS CRAZY. The plant is digesting the ants. Every time I see a dead ant, it is covered in a fungal mat, and I wonder if that fungus helps Cecropia digest dead Azteca ants. Azteca live in big colonies, and there’s a lot to digest, and maybe the fungus makes the digestion more efficient.
In my short time here, I decided to study how microclimate (shadiness, temperature) affect a Cecropia-Azteca symbiosis. I think the Azteca keep their young and their mealy bugs toward the top of the Cecropia tree where it’s warmer. I also think trees in full sun have bigger ant colonies and healthier leaves. I think the mealy bugs are more abundant in warmer places with more sun. But I could be completely wrong. Either way, I’m only asking one question, and I bet I’ll be back one day to ask more.
I came to Panama to learn about tropical ecology and to do a small project. I’ve been here for four days, most of which I’ve spent in the rainforest, and this place is really unlike anywhere I’ve ever been. The forest is one big pulsing center of life. The tree leaves and trunks are covered in multi-colored mosses. Spiders hang under leaves and wait for herbivorous insects to show up. The ant group with the smallest colony of any known in the world builds its nest in a single rotting stick in the leaf litter. It’s mandibles are shaped like sickles for ripping apart millipede spines. Trap jaw ants snap their mouths shut so hard, you can hear it. Leaf cutter ants make trails of moving leaves beside our field house door.
There are critters making a living everywhere. One can stare at a leaf and see animals compete, cooperate, and eat one another. The number of species and the space they occupy here makes one wonder why there is so much empty space in temperate forests. Scientists have been wondering that forever, and now I join the party.
Here are a few animals from the forest:
Tiny tarantula! (Saricopelma panamense?)
A caterpillar that looks like crazy go-go boots. (Limacodidae?)
How absolutely adorable. I’m guessing this is a lacewing larva, also called a ‘trash bug’.
‘Tis the season. Cankerworms, better known as inchworms, are once again unwelcome ornaments in our hair. I know almost nothing about them except it is really fun to people watch when they arrive, and they rain on me whenever I go to clip a branch from a tree.
The other day when I was sampling a cankerworm-infested tree, I noticed a swarm of noseeums at my feet. Then the noseeums started poking the caterpillars with their back ends.
So I delight in sharing this video of some very persistent parasitoids (braconids) sticking it to a cankerworm. Take it away, ladies.
As I write this my front yard is abuzz with small bees. Many are flying around just above the ground while others fly back and forth to redbuds and camellias gathering pollen.
Although these bees do not generally sting I watch as mothers nervously cross the street with strollers. Neighbors pass by and comment “Watch out for all those fire ants” referring to the small mounds that dot my sparsely vegetated lawn.