Planthoppers are bugs that first appeared in the fossil record several hundred million years ago. Scientists at the University of Oxford have now identified a unique organ in planthoppers that can create a snapping motion with a combination of elastic recoil and muscle contraction. The findings show how tiny animals are able to communicate over long distances with sounds that we can't hear. The scientists have reported their unexpected discovery of this organ in PLOS Biology. The work may benefit agricultural research; planthoppers are a major carrier of a serious rice virus.
“I was studying 3D images of planthoppers that I had collected using X-ray imaging in a particle accelerator, trying to understand the evolutionary relationships between different groups,” said the lead author of the work, Leonidas-Romanos Davranoglou of the Department of Zoology. “But as I dissected the bugs in virtual reality on my computer, I immediately realized that I was looking at something entirely new, so decided to investigate further.”
The planthoppers have very tiny muscles, which aren’t able to generate the force that would be required to produce powerful vibrations. They utilize stored elastic energy that is suddenly released, like a catapult. In this case, however, the energy that is released comes out in cycles and repetitively moves the planthopper's abdomen up and down. The so-called snapping organ is a complex biological structure that can rapidly open and close.
For this work, the scientists gathered hundreds of live planthopper specimens from hills surrounding Athens. After returning to the laboratory with the bugs, they used laser vibrometry, microtomography, high-speed video, and confocal microscopy to investigate the mechanism of the snapping organ. The researchers turned to the Department of Engineering at the University of Oxford to develop a mathematical model for their observations.
Many different planthopper families were found to carry this vibratory organ.
“These insects include several economically important pest species, including the brown planthopper, which is one of the most serious pests on rice in the developing world. Understanding how these insects signal to each other may help in disrupting their communication channels or detecting their calls,” said the senior author of the study Dr. Beth Mortimer of the Department of Zoology.
“Silent to the ear, the planthoppers have come up with their own novel way to communicate with potential mates. You could say it’s their form of snap chat,” she added.
We may have just discovered the snapping organ, but this method of communication is ancient; it's thought to be at least 250 million years old.