Fruit flies are already famous in science. They’ve helped researchers make discoveries in genetics, aging, and brain function.
Now, scientists at UC Santa Barbara have found that fruit fly larvae have a surprising sixth sense—they can detect electric fields.
This ability, called electroreception, is common in animals like sharks and bees, but had never been seen in fruit flies until now.
Led by Professor Matthieu Louis, the team discovered that fruit fly larvae move toward the negative pole of an electric field.
This behavior was uncovered by Julia Riedl, a student in Louis’ lab at the time. Instead of testing molecules, she used a common lab tool called gel electrophoresis to test the larvae.
When placed in an electric field, the larvae quickly turned and crawled toward the negative end—showing a clear response to the invisible force.
The team wanted to find out how the larvae could sense the field. They used genetic tools to turn off different nerve cells in the larvae, one group at a time, until they found the specific neurons responsible.
These cells were located on either side of the larva’s head, near the area involved in smell and taste.
Using special proteins that glow when neurons are active, the scientists watched the cells light up under a microscope when exposed to electric fields.
Surprisingly, only one neuron in this cluster responded. It became less active when the positive pole was in front of the larva and more active when it was behind, causing the larva to turn around.
This tiny cell acted like a compass needle, guiding the larva through its environment.
The study took over 15 years to complete. That’s partly because electric fields are hard to study. They’re invisible and tricky to separate from other things like heat, acid levels, or electric current.
With help from experts in electrochemistry and engineering, the team created advanced models to understand what was really happening in the experiments.
They confirmed that the larvae were responding specifically to the electric field—not the electric current or other factors.
As for why fruit fly larvae evolved this sense, the scientists have a few ideas. It could help them find the best spots in rotting fruit to grow—areas with more sugar and less alcohol, which naturally create electric differences. It might also help them avoid predators like wasps, which carry a positive charge when flying.
The discovery has big implications. Unlike most animals that sense electricity, fruit flies are easy to study in the lab. This means researchers can now explore the genes and brain functions behind electroreception.
The findings could also inspire new technologies. Just as light-sensing genes led to optogenetics (controlling cells with light), this discovery could lead to methods for using electricity to influence cells—perhaps in ways that are less invasive than current tools.
Understanding how a tiny fruit fly larva senses the world could help scientists unlock secrets in fields from biology to bioengineering.
