High-resolution Measurement of Odor-Driven Behavior in Drosophila Larvae

Summary

In this video article, we describe a new method allowing the construction of odorant gradients with stable and controllable geometries. We briefly illustrate how these gradients can be used to screen for olfactory defects (full and partial anosmia) and to study more subtle features of chemotaxis behavior.

Abstract

Olfactory responses in Drosophila larvae have been traditionally studied in Petri dishes comprising a single peripheral odor source. In this behavioral paradigm, the experimenter usually assumes that the rapid diffusion of odorant molecules from the source leads to the creation of a stable gradient in the dish. To establish a quantitative correlation between sensory inputs and behavioral responses, it is necessary to achieve a more thorough characterization of the odorant stimulus conditions. In this video article, we describe a new method allowing the construction of odorant gradients with stable and controllable geometries. We briefly illustrate how these gradients can be used to screen for olfactory defects (full and partial anosmia) and to study more subtle features of chemotaxis behavior.

Protocol

1. Equipment and Reagents

Odor dilutions:

• Paraffin oil (Sigma, CAS number: 8012-95-1)
• Odors of the highest purity available which elicits attraction in Drosophila larvae¹. In this video article, animals were tested with isoamyl acetate(Sigma, CAS number: 123-92-2).
• 1.5ml glass vials with Teflon cap (Agilent Technologies)
• Digital measuring scale for precise dilution by weight

Assay arena set-up:

• Agarose (Promega)
• Lids of 96-well Microplate (BD Falcon, catalogue number: 353071). Our behavioral arena consists of three stacked lids.