This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A pregnant female Ormia ochracea fly has a challenging problem to solve. She must listen for the song of a male cricket, locate him in the dark and use him as a host for her developing offspring.
But first, she has to decide whether that song is worth chasing. New research published in the Journal of Experimental Biology reveals that the answer is more complicated than scientists previously understood. Olaf College found that female Ormia ochracea—small, yellow, crepuscular flies that implant their larvae in crickets—do not recognize attractive cricket songs based solely on their beat, or pulse rate.
Instead, the flies evaluate multiple aspects of the songs' timing. Two songs with the same pulse rate can produce dramatically different responses. "Two songs can have exactly the same pulse rate but mean very different things to the fly," said lead author Lauren Bitner, a postbaccalaureate research associate in the Lee Lab of Neural Systems and Behavior at St.
"What matters isn't just how quickly the sound pulses repeat, but how the fly pays attention to the way the rhythm is constructed." Cricket songs may sound simple, but their rhythms can be composed in many ways. Each song consists of sound pulses separated by periods of silence. A particular pulse rate can therefore be produced by short pulses and longer silences, or longer pulses and shorter silences.
The researchers took advantage of this distinction by creating artificial cricket songs in which they could independently vary the duration of sound pulses and the silence between pulses. They then presented the songs to pregnant female Ormia ochracea and measured how strongly the flies responded. The experiments revealed a striking pattern.
Pulse rate predicted some of the flies' behavior, but it could not fully explain which songs they preferred. Songs with the same pulse rate sometimes elicited very different responses depending on the specific combination of sound and silence. Instead of listening for a single "magic number" of pulses per second, the flies appear to recognize relevant cricket songs based on combinations of timing features.
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