Electric fields may mess with fruit fly wings

"Static electric fields are all around us but for a small insect like a fruit fly it appears these fields' electrical charges are significant enough to have an effect on their wing movement and this means they will avoid them if possible," says Philip Newland. (Credit: iStockphoto)

Static electric fields can disturb the wings and alter the behavior of fruit flies, new research shows.

The findings suggest that because laboratory fruit flies live in plastic housing, which holds its own static electric charge, this could agitate the flies and change their behavior and neurochemical profile. This, in turn, has the potential to impact or confound studies for which scientists use the flies.

“Fruit flies are often used as model organisms to understand fundamental problems in biology,” says Philip Newland, professor of neuroscience at the University of Southampton and lead author of the study. “Seventy-five percent of the genes that cause disease in humans are shared by fruit flies, so by studying them we can learn a lot about basic mechanisms.

“Plastic can retain a charge for a long period and, given the use of plastic in the rearing of these insects and other small insects such as mosquitos, long-term exposure to these fields is inevitable.”

Flies in the Y maze

The researchers put fruit flies in a Y-shaped maze, with one arm of the maze exposed to an electric charge and the other receiving none. They found the flies avoided the charged chamber and gathered in the non-charged arm.

Interestingly, flies with no wings didn’t display this behavior, and flies with smaller wings only avoided higher charges. This suggests that the wings of the fly are involved in detection and are affected by the fields.

This was borne out when subjecting stationary flies to electric fields. Fields about as strong those that produced the avoidance behavior could manipulate the wings of the flies, report the researchers.

“When a fly was placed underneath a negatively charged electrode, the static field forces caused elevation of the wings toward the electrode, as opposite charges were attracted,” says Newland.

“Static electric fields are all around us but for a small insect like a fruit fly it appears these fields’ electrical charges are significant enough to have an effect on their wing movement and this means they will avoid them if possible.”

Brain chemistry

The effect on the wings being moved seems to agitate the flies, as revealed by changes in their brain chemistry. Flies exposed to an electric field showed increased levels of octopamine (similar to noradrenaline in humans), which indicates stress and aggression. The flies also showed decreased levels of dopamine, meaning they would be more responsive to external stimuli.

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As well as having consequences for flies used in laboratories, the results also have implications for flies in their natural environment.

“We are particularly interested in how electric fields could be used in pest control,” says coauthor Christopher Jackson. “Meshes that can generate static electric fields could be put across windows of houses or green houses to prevent insects like fruit flies or even mosquitos entering, yet allow air movement.

“It also raises questions of how pollinating species like bees could be affected by power lines, which have stronger electric fields.”

The work appears in Proceeding of the Royal Society B.

Source: University of Southampton