A comparison of feeding rate methods in Drosophila melanogaster indicates that consumption is influenced by body size

Abstract

Dietary restriction, a decrease in nutrient intake without malnutrition, has been shown to increase life span in many species and is highly linked to feeding behavior. Although Drosophila melanogaster is an excellent model organism to study the effects of dietary restriction on life span and associated traits, measuring feeding rate in this organism is particularly challenging. Several methods have been used to estimate feeding rate in Drosophila melanogaster, but it remains unclear which method is most precise. We examined the effectiveness of two popular methods that label media with blue dye or radioactive isotopes to quantify food uptake. We found that the radioactive label assay was more precise than the blue dye assay and likely most useful for comparing the effects of different treatments (genotypes, diets) on feeding rates. We found that the relationship between feeding rate and dietary treatment depends on the size of the fly, so we also suggest incorporating body size as a covariate in data analysis to improve the accuracy of feeding rate estimates.