Drosophila Suzukii

Edit: This is in need of a rewrite and an update. It's on my list.
So I've kept kinda quiet about this up to now(at least on this blog if nowhere else), but I figure I might as well recount what's happened in the week or so leading up to this post. It's a long and convoluted story, so you might want to get comfortable.
This all starts with a rather simple lab in Sophomore year biology: paper cutouts of different colors were thrown on different patterned/colored backgrounds, the students had about half a minute to grab cutouts, then the cutouts were tallied, and replaced with more cutouts of equally proportioned colors, and the cycle was repeated. Pretty standard demonstration just to show how unconscious (and hence somewhat natural) selection can have huge effects on allele frequency. Simple enough. However, after reading Richard Dawkin's book, The Greatest Show On Earth, and learning Dr. Lenski's brilliant E. coli experiment (as wells as several others mentioned in the book), I wanted to try to take this a step further.
My initial idea was to attempt this with rotifers and vary the salinity of their solution, but several problems with this quickly showed up. I wasn't sure where to find a food (algae presumably) that could endure both salt and fresh water, and didn't want to have to worry about varying algae populations. I wasn't certain how to quantify changes that could occur in the rotifers, and I wasn't sure how I was going to get a culture of water with only rotifers in it, to minimize predation. None of these things are unresolvable, but it was certainly enough for me to start shopping around for other options.
At this point (Early October), I began to correspond with my AP Bio teacher. He suggested using fruit flies(D. melanogaster) as the species of interest, given their short generation time, and the large number of mutations that have been breed out over time (not to mention the fact that AP Bio already has a fly lab, and thus I would have samples to work with). I agreed. I was, however, slightly worried that all the domestication would lead to a lack of variation: that all the flies (with the exception of the afore mentioned mutations) would effectively be genetically identical. I proposed catching wild flies, and then breeding them with the mutated flies to get a nice mix of both extreme mutation, and more subtle variation. So far so good.
Noticing a lot of fruit flies around our compost bin, I set out to capture some. My initial attempts at suctioning capture devices were no good. I inhaled three flies by accident, before realizing that even those flies I didn't ingest were dying of shock. I finally developed a more successful method, namely trapping the fruit flies under a test tube, then knocking it against a funnel until the flies fell into a larger jar. This worked pretty well, and over the course of a weekend, I had four colonies set up. This whole time, I wasn't paying a whole lot of attention to what I was catching (I actually later found a single mosquito in one of the colonies. Presumably I mistook it for a fly at the time). In any case, I didn't notice anything strange until the following Wednesday, when I first saw my flies next to the D. melanogaster from the lab. The first thing that stood out was the size. The wild flies (henceforth just my flies) were a lot bigger than the domesticated ones, as much as twice the size. There was also a significant variation in size among my flies, and several other strange features: the wings were a lot longer in proportion to the body, and some of the flies had spots on their wings. I admit, my first though was "That's just the local subspecies. It's good the flies are this strange, it'll help to introduce a lot of variation". In retrospect, this was exactly the wrong thing to think. My AP Bio teacher, however was spot on, suggesting that I might even have several Drosophila species in my cultures.
We went back and forth in email for a while, me (wrongly) arguing that there was only one species, my teacher arguing for multiple species. I'm pretty stubborn, and despite the fact that he had some extremely compelling arguments for why the flies couldn't be D. melanogaster, and why further more, they couldn't be the same species, I continued to assert that they were. If I learn anything from this experience, I hope it's that I should have given in as soon as he presented his evidence. It probably would have saved my some time.
In any case, I began (semi-secretly) searching for other species of Drosophila that I might have captured. I found one. Remember those wing spots? On an impulse,I googled "Wing Spot Fruit Fly". The fifth result? "Potential Fruit Fly Invasion Serious Threat For Oregon". I clicked it. The more I read, the more matched up. My flies were Spotted Wing Drosophila(Drosophila Suzukii), an invasive fly. I emailed my biology teacher, and after some deliberation, he agreed with me. We sent a sample home with a classmate of mine whose father works at the local extension agency. I also sent a sample up to the Department of Agriculture in Salem. And guess what? Apparently, not only was I right, but my flies are the first to be confirmed in my county! I got on the front page of the Locals section in two papers! Cool!
So what next? Well, I plan to do my selection lab with either them or the D. immigrans flies I caught at the same time, and I'll now be studying SWD overwintering patterns in the wild. I also MAY have discovered something quite neat, and also quite important, about SWD breeding in the lab, but I'll have to confirm it with experimentation before I post it here and make myself look like a fool.
Till Next Time,

P.S. anyone on the west coast interested in tracking SWD populations near them should go here, where Mark Bolda has an excellent set of posts describing how to make and bait traps for them.


  1. ok, i've just added a new procrastination website to my list. your blog is really cool and full of neat stuff! perfect inspiration for these days when i'm finding it so tedious to work. :)
    and your early posts are definitely not just you "ranting about feelings" :)

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