We Have Cytoplasmic Incompatibility! Wasp Research Results!!

It. Has. Happened.

On Wednesday, Dr. Hunter, Suzanne, and I took a close look at our data sheet that contained all of the information from those four hardcore weeks of experiments, and determined--once and for all--that the bacterial symbiont, Wolbachia, causes cytoplasmic incompatibility (CI) in Eretmocerus emiratus wasps. CI is the term that describes the process where sperm from an infected male can't fertilize an uninfected female's egg because the cytoplasm from the male's cells is incompatible with the cytoplasm from the female's cells. An uninfected male can still successfully reproduce with an infected female, and wasps with the same infection status can, of course, reproduce with each other. In crosses between infected males and uninfected females, male wasps can still be produced, since they develop from unfertilized eggs.

We determined that CI was indeed occurring between W+ males and W- females by comparing the amount of wasp eggs that developed on whitefly host as compared to the amount of eggs laid. In matings between W- males and females, most of the eggs that were laid (approximately 64%), developed successfully into adult wasps, whereas in matings between W+ males and W- females, less than half of all eggs laid (approximately 39%) developed into adult wasps. The fun part about all of this is that even though there was a pattern when the data was examined overall, both testcrosses contained interesting variations. For example, although most of the results from the individual W+/W- dishes did suggest CI, there were a few dishes in which 70% or more of the wasps developed, with significant amounts of females in them. Similarly, there were W-/W- dishes in which less than 20% of wasps made it to adulthood. How odd!

Oh, but I should mention that since we're all good scientists over at the Hunter Lab, we do have to confirm our results through DNA extraction and PCR/gel electrophoresis, so that's what we're doing now. Today, we started on this by doing two DNA extractions sets of our wasps (which we had kept frozen in a -80 degree Celsius freezer) to determine their infection statuses. Hopefully we didn't screw up too badly in the experiment, since these are significant results. I guess I should mention that my experiment was not the first of its kind. A few years back, a foreign exchange student from Israel named Elad Chiel, tried to determine whether Wolbachia caused CI in E. emiratus, but he got contradictory results from multiple experiments. Our experiment was more thorough than his, and involved a few more reliable techniques (such as mating observations in leaf dishes rather than in vials, so that wasps could mate in a more natural environment).