Why do flies buzz around when the air is still? And why does it matter?
In an article published online by the scientific journal on July 26, 2024 Current biology, University of Nevada, Reno assistant professor Floris van Breugel and postdoctoral researcher S. David Stupski respond to this as yet unanswered question. And that answer could be a key to public safety, especially how robotic systems can be better trained to detect chemical leaks.
“We currently do not have any robotic systems to detect odor or chemical plumes,” Van Breugel said. ‘We don’t know how to efficiently find the source of a wind-borne chemical. But insects are remarkably good at tracking chemical plumes, and if we really understood how they do it, we might be able to train cheap drones to use a similar process. to find the source of chemicals and chemical leaks.”
A fundamental challenge in understanding how insects track chemical plumes – how does the fly find the banana in your kitchen? — is that wind and odors cannot be manipulated independently.
To tackle this challenge, Van Breugel and Stupski used a new approach that makes it possible to remotely control neurons – specifically the ‘smell’ neurons – on the antennae of flying fruit flies by genetically introducing light-sensitive proteins, an approach which is called optogenetics. . These experiments, part of a $450,000 project funded by the Air Force Office of Scientific Research, made it possible to give flies identical virtual odor experiences in different wind conditions.
What Van Breugel and Stupski wanted to know: how do flies find a scent if there is no wind to carry it? After all, this is probably the wind experience of a fly looking for a banana in your kitchen. The answer is in the Current Biology article: “Wind Gates Olfaction Driven Search States in Free Flight.” The print version will appear in the September 9 issue.
Flies use signals from the environment to detect and respond to air currents and wind direction to find their food sources, Van Breugel said. In the presence of wind, these signals trigger an automatic ‘cast and surge’ behavior, in which the fly darts into the wind after encountering a chemical plume (signaling food) and then casts – moving back and forth – when it loses power. odor. Cast-and-surge behavior has long been understood by scientists, but Van Breugel said it was fundamentally unknown how insects searched for an odor in still air.
Through their work, Van Breugel and Stupski discovered another automatic behavior, sink and circle, which involves lowering altitude and making repeated, rapid turns in a consistent direction. Flies perform this innate movement consistently and repeatedly, even more so than cast-and-surge behavior.
According to Van Breugel, the most exciting aspect of this discovery is that it shows that flying flies are clearly able to assess the conditions of the wind (its presence and direction) before deploying a strategy that works well under these conditions. The fact that they can do this is actually quite surprising: can you tell if there is a gentle breeze when you stick your head out the window of a moving car? Flies not only respond to an odor every time with the same pre-programmed response as a simple robot, they respond in a context-oriented manner. This knowledge could potentially be applied to train more advanced algorithms for odor-detecting drones to find the source of chemical leaks.
So, the next time you try to swat a fly in your home, keep in mind that flies may be a little more aware of their natural environment than you are. And maybe just open a window to let it out.
