Drosophila have one of the best characterized olfactory systems of any animal (for a great overview, read Benton, 2022). Flies use olfaction to navigate in their environment and fly upwind into an odor plume to find a potential food source (Budick & Dickinson, 2006; Gaudry et al, 2012), even over long distances (Dickinson, 2014).
Response to odors are typically measured by looking at the flies’ locomotion, orientation and navigation towards an odor source. In these assays, complex odor blends (like odors found in rotting fruit generally evoke the strongest behavioral responses, but they are also responsive to pheromones and stress odors (Benton, 2022). Growing evidence also suggests that when flies do not visibly respond to an odor, they might still be meaningfully processing the olfactory information. For example, odors can affect taste sensation (Oh et al, 2021; Junca et al, 2021), food ingestion and metabolism (He et al, 2022) and influence stress response and lifespan (Libert et al, 2007).
All of this suggests that Drosophila have a sensitive sense of smell, and their behavior is affected by odors in their environment. So how does this impact your behavior experiments? It essentially means that you need to be aware of the ambient smells in the environment where you are recording the flies’ behavior:
Don’t perform behavior experiments near strong odor sources (like the lab garbage or where you store old stocks)
Be aware of strong smells in the lab and record in your notebook when the smell was present and its potential known odor source (for example, if someone is performing Westerns and the smell of 2-Mercaptoethanol permeates the lab when you are running behavior, make sure to write that down)
Don’t perform behavior experiments where fly food is being made
Try not to perform behavior right next to a CO2 station
Don’t wear perfume or cologne when performing behavior experiments (We have found that perfumes and colognes can affect where the flies like to be in an arena, and how active they are).
Make sure your body odor is not noticeable (ie wear deodorant)
Do you have other tips and tricks? I’d love to hear them!