IISc Tteam Studying how Insects Talk

Fascinating details are emerging from analyses of sounds recorded in rain forests and elsewhere

Published: 14th March 2015 06:03 AM  |   Last Updated: 14th March 2015 06:03 AM   |  A+A-

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MALLESWARAM: The way animals talk to each is the focus of Dr Rohini Balakrishnan, a professor and an ecologist at the Centre for Ecological Studies at the Indian Institute of Science.

Experiments in lower animals have shown that their voice boxes are absent or not well developed. Then how do these animals communicate with each other?

For the past 10 years, Rohini Balakrishnan’s team has worked on different aspects of acoustic signaling and communication in crickets and katydids. The chorus of insect sounds we hear as dusk falls, when near vegetation, is usually from these creatures.

A combination of environmental factors seems to contribute to the method of communication. This team is actively exploring the dynamics of communication of species in a rainforest where the ambient acoustics may drown out the call of the individual, says a press note.

The team uses this information to produce acoustic simulation models that can create 3-D soundscapes: the forest viewed through its sounds and the ears of its inhabitants. In the rainforest where they have worked, their study has shown that the loud cacophony we hear often dissolves into silence when perceived through the ears of crickets!

A bird called the racket-tailed drongo mimics the calls of other animals and has a voice box as does the Asian elephant. The researchers are trying to understand why vocal variations are exhibited by these animals and to describe their vocal repertoires.

Research has revealed that during the breeding season, male crickets and katydids rub a small plectrum-like (a thin, flat piece of slightly flexible material) structure on one of their wings against a row of teeth on the other wing to produce a sound named “the calling song.”

The IISc team has recorded these calling songs of crickets, and digitised and analysed them using computer programs that measure the frequency and timing patterns.

One of the team’s aims is to use these digitised calls to identify species and individual insects. Using these acoustic signals to identify species could be less invasive than pitfall trapping or baiting, as the insects stay undisturbed after the researcher is done with sampling, unlike the other methods which involve researchers handling these fragile creatures.

Rohini Balakrishnan’s team aims to develop and validate databases of acoustic signals of various species. Such databases could use these signals to identify different animals within specific groups of organisms, without actual physical contact. Periodic biodiversity monitoring with an automated recorder installed in an environment could help perform such biodiversity monitoring exercises.

“A detailed understanding of senders, signals, signal distortion and receivers would provide insights both into the functioning of complex natural communication networks and the evolutionary forces that do or do not drive them,” she says.

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