Ever thought about eavesdropping on a bug?
That’s what Princeton University doctoral student Micah Fletcher does as he explores the maternal behaviors of the treehopper species Publilia reticulata. These insects use vibrations to attract mates, signal distress, hush youngsters and in other communications.
In a field outside The Watershed Institute, Micah uncoils a tiny microphone and clips it to an ironweed plant. Similar to how a record player’s needle reads the grooves on an LP, his device converts a treehopper’s vibrations on a plant into sound.
“One interesting thing they do is communicate to each other using sound. Instead of airborne sounds, it is plant-born vibration. It is similar to cicadas and katydids and crickets – instead of air, it vibrates the plant,” Micah said.
These treehoppers are about the size of a large grain of rice and a modest brown hue, unlike some of their brightly colored cousins in Central and South America. Micah, who delighted in spiders as a young child, became fascinated with treehoppers in college at the University of Missouri.
“These are little charismatic animals that have behaviors that are just as complex as mammals and birds and we know so little about them,” he said. “It is a part of the natural world that is a complete mystery and there is so much for us to uncover.”
Many of the 3,500 treehopper species have distinct sounds, he said, and some species produce an entire repertoire of signals.
For example, there is a Marco Polo type of duet during mating in all treehopper species studied-to-date. Baby treehoppers share information on where a plant’s tasty bits are located as they move around eating. Mother treehoppers, who guard their eggs, cooperate with each other by giving alarm signals about predators.
Micah, 24, and his research assistant, Caroline Beardsley, 21, a recent graduate from Rutgers University, are following the mother treehoppers through their reproductive lives from May through August.
“When I first heard the vibrational communication, it was insane – it wasn’t what I thought it would sound like. They sound like birds,” Caroline said.
For this summer’s research phase, Micah is exploring how long mothers protect their eggs and the timing of when they leave the nymphs to start a new clutch.
Interestingly, these mothers have helpers. The treehoppers suck the sap from plants and excrete “honeydew”, which attracts ants. These ants become nannies, who protect the nymphs and free up the treehopper mother to lay new eggs.
“It is a mutualism, so the ants get sugar water in exchange for protecting the treehoppers from invertebrate predators like spiders, stink bugs, and assassin bugs,” Micah said.
He said the Watershed offered him a cordoned-off area to conduct his research, as well as access to the laboratory. The fact that a seminal study on treehoppers was done at the Watershed in the 1980s factored into his decision to do his research here. He plans on publishing his findings in scholarly journals and in his dissertation.
Along the way, Micah has refined the way he records the treehopper’s sounds. Eventually, he would like to create an affordable listening mechanism so young scientists can eavesdrop on bugs, too.