Feeding Test: Assessment of Feeding Preferences in Drosophila melanogaster

Abstract

Source: Bovier, T. F., et al. Methods to Test Endocrine Disruption in Drosophila melanogaster. J. Vis. Exp. (2019).

This video describes a feeding assay for fruit flies in which colored food is used to monitor feeding and the effect added compounds may have on feeding activity. The example protocol tests the effects of several endocrine disrupting chemicals (EDC).

Protocol

This protocol is an excerpt from Bovier et al., Methods to Test Endocrine Disruption in Drosophila melanogaster, J. Vis. Exp. (2019).

1. Feeding Assay

NOTE: This assay is recommended to test if the presence of the selected EDC in the medium could affect feeding of flies.

1. Put 15 young flies in vials containing Cornmeal medium (CM) supplemented with different concentrations of the selected EDC and a coloring food. Allow flies to feed on the media for 1 day.
   NOTE: For example, use red dye no. 40 (1 mg/mL).
2. Put 15 young flies in vials containing CM supplemented with the solvent alone and a coloring food for control. Allow flies to feed on the media for 1 day.
3. Anesthetize individually each group of flies with ether.
   1. Transfer flies of each group to a cylindrical glass container (etherizer) with a funnel inserted into the open end, inverting the vial over the funnel and gently tapping the two containers together to make the flies fall into the etherizer.
      NOTE: The funnel will prevent them from getting out of the etherizer.
   2. Knock flies down by gently tapping the etherizer on a soft surface, such as a mouse-pad, and quickly replace the funnel with an ether-soaked cotton and gauze plug.
   3. Wait about 1 min until the flies fall to the bottom and stop moving.
      NOTE: Do not exceed the time or the flies will die.
4. Put immobilized flies under a stereo-microscope and compare the abdominal coloring of each treatment group with respect to the control group.

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
17α-Ethinylestradiol	Sigma	E4876-1G
Agar for Drosophila medium	BIOSIGMA	789148
Bisphenol A	Sigma	239658-50G
Bisphenol AF	Sigma	90477-100MG
Cornmeal	CA' BIANCA
Diethyl ether	Sigma
Drosophila Vials	BIOSIGMA	789008	25 mm x 95 mm
Drosophila Vials	BIOSIGMA	789009	29 mm x 95 mm
Drosophila Vials	Kaltek	187	22 mm x 63 mm
Ethanol	FLUKA	2860
Etherizer	Crafts		cylindrical glass container with a cotton plug
Hand blender Pimmy	Ariete		food processor
Instant Success yeast	ESKA		Powdered yeast
Red dye no. 40	SIGMA	16035
Stereomicroscope with LED lights	Leica		S4E