Quantitative analysis of feeding behavior in Drosophila

Drosophila has become a powerful model organism in neuroscience research not only due to its molecular genetics toolkit, but also due to the successful development of methods and protocols to monitor and annotate behavior. Feeding and foraging are central elements in a majority of behavioral assays, but their quantification and analysis is a major challenge in the fly. We have developed flyPAD – fly Proboscis and Activity Detector, a method to automatically monitor feeding behavior quantitatively in individual flies. Our method is based on capacitive measurement of a fly’s interaction with the food. The precision of the measurements allows for high fidelity, high temporal resolution, and unbiased measurements of feeding behavior. We demonstrate that flies ingest food by rhythmically extending their proboscis with a frequency that is not modulated by the internal state of the animal. Instead, hunger and satiety homeostatically modulate the microstructure of feeding. These results highlight similarities of food intake regulation between insects, rodents, and humans, pointing to a common strategy in how the nervous systems of different animals control food intake. This method complements our continuing experimental and quantitative modeling approaches to understand how the internal state affects foraging and feeding strategies to achieve nutrient homeostasis.