17 Foraging in Flies and Worms

Abstract

Food acquisition is a cornerstone in the struggle for animal survival. The mechanisms by which animals locate, evaluate, and acquire food are often defining features of a species and are manifested in its anatomy, physiology, and behavior. For example, foraging strategies can strongly shape sensory modalities (e.g., hearing in owls; electric organs in fish; echolocation in bats). Foraging success is probably a prime mover in the evolution of more complex behaviors; e.g., group hunting (wolves, orcas) and colonial life in insects (Wilson 1975; Choe and Crespi 1997). Our goal in this chapter is twofold: to provide a brief but not exhaustive overview of foraging in the insect Drosophila melanogaster and the nematode Caenorhabditis elegans, and to identify areas for future research.

What do we mean by foraging? Here we use foraging to encompass food-related behaviors. This includes animal responses to food and food-derived cues, and patterns of food intake. Many of the challenges associated with foraging by Drosophila and Caenorhabditis are general. For example, in both organisms foraging is affected by environmental factors such as food quality, distribution, and abundance; smell; taste; and intra-and inter-species competition. Recognizing this complexity lays the groundwork for thinking about the neurobiology of foraging. By neurobiology of foraging we mean the circuits and molecules regulating foraging and how these features respond to ever-changing environments internal and external to the animal.

FORAGING IN C. ELEGANS
C. elegans (Fig. 1) is a free-living nematode that lives at the air/water interface in decaying organic matter. It feeds on...