Friday, February 17, 2017
Exhibit Hall (Hynes Convention Center)
Amanda Macke, Central City High School, Central City, NE
Jasmine Wilson, Central City High School, Central City, NE
This project was designed to examine the potential desensitization of insects to DEET, the most commonly used insect repellent, and to determine whether essential oils may be comparatively effective in repelling insects. The hypotheses predicted that if Drosophila melanogaster were exposed to DEET repeatedly, there would be an effect on their sensitivity to DEET and as concentration increases, there would be an effect on the number of flies exhibiting normal geotaxis. The hypotheses also predicted that essential oils would repel insects at a similar rate to DEET. To test the effect on geotaxis, flies were placed in vials with filter paper treated with different concentrations of each substance at the top. Data was recorded on the number of flies that moved to the top of the vial. For each concentration, 5 trials of 10 flies were conducted. To test the desensitization to DEET, F1 flies were placed in T-tubes and given the choice between water, DEET, and essential oils. The location of each solution was intentionally randomized on the T-tube. After data was taken, flies were placed in vials labeled with their choice and allowed to reproduce. The process was then repeated with the F2 through F4 generations. There was a downward trend in the first three DEET generations, but in the fourth generation, the repellency rate returned to that of the first generation. There was also an increased sensitivity to essential oils. Recommendations include more concentrations with smaller intervals between, varied amounts of time tested with concentrations, more generations, and higher significant figures.