I grew up in pretty remote areas and spent a lot of my youth out in nature watching animals (especially insects). That being said, I know embarrassingly little about what Drosophila really do in the wild. Truth be told, I feel guilty admitting this since my PhD thesis in Marla Sokolowksi’s lab was on natural variation of feeding and foraging behaviors.
The truth is that most of what we know about Drosophila melanogaster behavior comes from laboratory experiments. Traditionally scientists that design these experiments don’t even think about what the flies’ natural environment would be like - the goal is always to get the fly to perform the behavior you want to see in as little time as possible. So a lot of the time we squeeze them into itty-bitty chambers so they interact with each other (a la courtship chambers), long, skinny tunnels so they move a lot (a la Drosophila activity monitors) and feed them food they would never really encounter in nature (a la almost every fly media ever used for Drosophila research since Ed Lewis published this: Lewis EB. 1960. A new standard food medium. Drosophila Information Service 34: 117–118).
In 2015 Teri Markow wrote a fantastic review called ‘The secret lives of Drosophila flies” as part of “The Natural History of Model Organisms” series in eLife. I love this review. Drosophila melanogaster are ecological generalists (ie they eat a variety of decaying vegetables and other plant matter) and it turns out they don’t live alone. They share their food substrates (which if you are a larva is also your home) with all kinds of microbes and other arthropods (i.e. bugs). So, they are quite social and spend a lot of time on rotting fruit where they aren’t necessarily feeding, but also interacting with other species of flies.
Raul Godoy-Herrerra from the Universidad de Chile has some great papers about what flies do in the wild too. A couple of my favorites of his are called “The behavior of adult Drosophila in the wild” and “Interaction and integration among behaviors of adult Drosophila in nature”. They look at what Drosophila melanogaster (and other Drosophilids) actually do in grape, apple, pear, and prickly pear orchards. Apparently, flies spend lots of time looking for food and oviposition sites, courting happens on fruit that is decaying, and larvae hide from ants. Flies also spend lots of time staying still in one place.
So, if we are laboratory scientists, why should we care? My thoughts are that if we design not-so-natural behavior chambers, that will tell us a lot about what flies are capable of, but maybe not much about what they actually do in a typical day. If we are dissecting out circuits and genes for behavior, we should probably give that some consideration since evolution is a pretty strong driving force for organization and function of such things.
My recommendation is this summer or autumn, you should plan to make a trip to a local apple orchard. Have some fun picking apples, but also take time to check out what is happening on those rotten apples that have fallen to the ground. You never know what you’ll discover!
Have more paper suggestions or first hand observations of Drosophila behavior in the wild? Please post in the comments below.