The effect of temperature on time spent in the dark by <i>Drosophila melanogaster</i>
The purpose of this study was to determine whether a long-term (48 hour) exposure to suboptimal temperatures would affect the time spent in the dark by Drosophila melanogaster. Many studies found that exposure to warmer temperatures led to a higher light intensity preference by D. melanogaster. Our prediction was that an exposure to cooler temperature would lead to less time spent in the dark and warmer temperatures would lead to more time spent in the dark. The fruit-flies were incubated at temperatures of 20°C, 24°C and 30°C for 48 hours before testing. The incubated flies were temporarily immobilized by anaesthetizing them with CO2 and then individually introduced to a T-maze apparatus, with one side having a light intensity of 2700 lux and the other having 0 lux. We found the amount of time spent in the dark during the three-minute test increased slightly, but not significantly (p-value = 0.8629) for the 20˚C and 30˚C treatments as compared with the 24˚C treatment. Therefore, we conclude that the time D. melanogaster spent in the dark is not affected by 48-hour temperature changes.