Slow Monday, Quick Wasps

Well, here we are again, a new week of wasp experimentation. I didn't post on Friday because I had a headache from all of the microscope work. Fortunately, I'm not too debilitated today, thanks in part to my Red Bull at lunch, but enough about that, since I've got to get into the good stuff.

Alright, so the main thing that I did on Friday was wasp harvesting, and I'm pretty sure that I detailed that in another post. For those of you who don't remember, harvesting involves removing leaves from a cowpea plant that has been infested with both whiteflies and wasps, and examining the underside of the middle-level leaves for wasp pupae housed in the cuticle of the dead whitefly larva host. Typically this is no special task, but on Friday, I got to harvest the pupae of the wasp, Encarsia hispida (not the one that I will be using for my experiment, by the way). An E. hispida pupa will have the following three characteristics: (1) dark pigmentation, which isn't seen in any Eretmocerus wasp species (Eretmocerus is the genus that I am working with), (2) two noticeable myconia (sp?), which are the final waste deposits of the E. hispida larva before pupation (also not seen in Eretmocerus), and (3) wiggling. That's right, E. hispida pupae actually spend their time wiggling (no other wasp, not even another Encarsia, do this)! This is a behavior that has not yet been explained, but the research director at the lab, Suzanne Kelly, believes that it is a defense mechanism against parasitism, because E. hispida pupae can be parasitized by male E. hispida larvae if the pupae are found by other E. hispida females.

Okay, onto today's stuff. Today, as you could tell from the title, was not an especially busy day. This morning, we infested some fresh cowpea plants with whiteflies, which is done by taking a clean plant from one cage, and placing it in a cage full of whitefly-infested plants. Not especially difficult, but very important. Next, some people from the lab and I went and visited the greenhouse on top of the sixth street parking garage, and I got myself some whitefly-infested plants from there. It is important to note that these are from a different culture of whiteflies than the one I previously mentioned--these are Rickettsia-positive whiteflies, and the ones I will be working with are Rickettsia-negative. This may not seem like a big deal, but cross-contamination must be avoided at all costs. Oh, Rickettsia is just another bacterial symbiont, but this one is found in whiteflies, and transmitted to Eretmocerus hosts when the wasps parasitize the flies. I don't really know much else about that symbiont, except that it won't be important for my project. So, I did actually use one of the ten plants I brought from the greenhouse to practice a whitefly larva flipping technique. Because the Eretmocerus wasps lay their eggs underneath the whitefly larva host, instead of actually injecting it into the host, it is necessary to flip the larvae over and count out how many eggs were laid by the wasps. It's fairly easy to flip the whitefly larvae when they are in their first instar, and are fat, but as they molt, they become wider and thinner, and harder to budge without destroying (the whiteflies do die during the flipping process, but destroying the host puts the egg underneath at risk for destruction; the egg dies as well, but it needs to be intact for us to see it). The wasp eggs are tiny and clear, so it takes practice spotting them, but they get easier to see fairly quickly.

I wrapped up the day by planting more cowpeas that I will use in maybe three to four days. Like I said, easy day.