Feeding Test: Assessment of Feeding Preferences in Drosophila melanogaster

- For this test, add food coloring to fly food to increase its visibility in the see-through abdomen of fruit flies. Then prepare vials containing the dyed food, the solvent, and the solutions of the chemicals of interest.

Make two control vials-- one with just the dyed food, and the other with dyed food and the solvent used for the chemicals. This is done to verify that neither the dye nor the solvent is not a deterrent to feeding.

Next, add young flies to each vial and allow them to feed under appropriate conditions. After feeding, anesthetize the flies and gently knock them out of the vial onto a piece of white paper. Keep each vial group separated.

Using a stereomicroscope, inspect the abdomen of each fly. Compare flies from each group with those from the control vial. Flies with a red abdomen have eaten the food, while those with a colorless abdomen have not.

In this experiment, we will assess the feeding preference of Drosophila melanogaster for selected endocrine-disrupting chemicals in ethanol.

- To assay the taste of the selected EDC, after anesthetization, transfer 15 young flies from the fly bed to four parallel vials containing cornmeal medium mixed with a food coloring. The control vial contains the solvent alone, and the three other vials are supplemented with different doses of the selected EDC's.

Keep the vials in a humidified incubator for one day with a natural 12-hour light.

After anesthetizing the flies again, transfer the immobilized flies to a white paper and place it under a stereo- microscope to observe. Compare the abdominal coloring of each treatment group with respect to the control group.