Entomology fieldtrip turns into a once in a lifetime opportunity
Dr Ben Warren (right) with entomologists from the University of Iowa
A University researcher has witnessed a once in a lifetime experience on a trip to the United States.
Entomologist, Dr Ben Warren, from the School of Psychology and Vision Sciences spent two weeks in Iowa where he saw the emergence of 17 year and 13-year periodical cicadas at the same time.
Periodical cicadas spend the majority of their life underground feeding on the sap from tree roots, emerging every 13 or 17 years in the spring. But this year both sets of periodical cicadas appeared at the same time – a 221-year phenomenon.
Dr Warren’s fieldwork trip formed part of a research study aimed at better understanding the evolution of insect hearing. He teamed up with Dr Mei-Ling Joiner and Professor Daniel Eberl from the University of Iowa to go into the field to find newly emerged cicadas, take them back to the lab and study their hearing organs or “ears”.
In contrast to mammals, insects have evolved ears at least 24 times independently. By studying cicadas Dr Warren’s lab will understand better how insect ears evolved.
Dr Warren said: "The ears of cicadas are amazing. They are jammed-packed with the auditory receptor cells – approximately 1000 per auditory organ. But even more perplexing is that these auditory receptors cells are all back-to-front and pointing in the opposite way compared to all other insect ears."
Cicada
Male cicadas are renowned for their loud mating call which can reach over 100 decibels. Both male and female cicadas have a pair of membranes in their abdomen called the tympanum, which functions as their ear drums and are connected to their auditory organ by a short tendon. Another organ, the tymbal, makes the distinctive trilling high-pitched sound. This sound is how females identify the right species to mate with.
Adult periodical cicadas only live for a brief period above ground – around three to four weeks and must mate before they die – hence the loudness of the mating call which can be as loud as a rock concert when calling en masse.
He added: “Treasure-hunting newly emerged cicadas in the field and watching them fly overhead in the morning sun was truly magical. With dodging tornados, jeep rides through the forest, light aircraft flying and a TV interview I felt like a true adventurer.”