No GPS fruit flies or “internal compasses” for food

How can fruit flies find a destination or companion without GPS, visual landmarks, etc.? U.S. researchers have found that fruit flies can find food or mates with the help of an “internal compass” that includes odors, the PhysicistS Network reported March 31. Because fruit flies’ sensory organs and sniffing patterns are similar to those of other animals, the latest research is expected to answer questions about how animals’ search for food affects the wider food ecology and environment. The team is currently studying the animal’s nervous system, muscle-to-body interaction, and how the environment affects its behavior, hoping for answers.

In the latest study, scientists at Drexel University converted nerve cells (olfactory nerve cells) that fruit flies respond to odors into photosensitive cells to map in detail the path seeking food, leaving and trying to return to food. To do this, they use light to stimulate receptor nerve cells that control the fruit fly’s sense of smell.

The entire study area is divided into three parts: the “central region” that activates the fly nerve cells, the “ring area” without any stimulus or direction hint, and the “border” between the two regions. When fruit flies are in the boundary area, the light intensity decreases, prompting the fruit flies to return to food.

Studies have shown that fruit flies use a simple and effective strategy to find food: once they are away from the location they are looking for (the core area), they slow down and turn around quickly. They also make some non-directional changes, such as frequent turning in the core area and longer stayining in the ring area.

In the core area, fruit flies use a path integration mechanism to measure the relationship between location and path to help the fruit fly find its way back. The researchers likened this approach to an “internal compass” where non-directional motion can be an effective mechanism for finding resources without directional cues. For fruit flies and many other animals, smell is an efficient sensory cue.