Summer brings a symphony of sounds as literally tens of thousands of species of insects share their mating repertoires across fields and forests. Crickets and katydids are some of the more audible contributors to the chorus. But there are hundreds of thousands of insect species sending their messages to each other that fall outside of our range of hearing. Dr. Carol Miles of the Department of Biological Sciences, working in collaboration with biologists at the University of Missouri and engineers at Binghamton University, is working to explain the mystery of insects that signal each other not through sounds audible to the human ear but through vibration of the tree branches upon which they rest. The male tree hopper (Umbonia crassicomis), a less than one-half inch long insect found in the neotropics of North America, has evolved a mating call that literally twists and vibrates the branch upon which he rests. He creates a relatively low frequency "wave" that moves along the branch. Once a female detects his call, she responds, and the male moves toward her, locating her by her calls.
This description of the behavior is relatively simple but understanding the mechanism by which the signals are produced and the neuronal processes by which the male and female respond are quite complex. One of Dr Miles' graduate students, Brianna Allison, is studying just how the male produces his signal. By implanting platinum electrodes with diameters smaller than a human hair to record the electrical signals generated by the insects' muscles, she has identified what muscles contract to produce the vibrations. Dr. Miles is also working with Dr. Quang Su, a mechanical engineer at Binghamton who is developing a device to mimic the movements of the branch. On that simulated tree branch Dr. Miles and another of her graduate students, Aaron Payne, will place insects implanted with the tiny electrodes to determine how the nervous system detects the vibrations. This information will help the team understand how these insects can locate each other using only the vibrations of the tree branch. Other members of the team include Drs. Reginald Cocroft and Satish Nair of the University of Missouri. Dr. Cocroft has studies this species for over a decade. Early on in his work, he helped explain the fundamentals of insect body movement in response to signal direction. As part of the team, Dr. Nair will develop a mathematical model to describe the process by which directionality is encoded. Together, this team composed of a neurobiologist, an animal behaviorist, a mechanical engineer and a mathematical modeler will help solve a mystery of nature which is of importance not only to biology but also to the science and industry of vibration detection.Back to Top
Last Updated: 8/26/09