Group 4 2012

Introduction

Crickets can achieve synchronization by either lengthening or their chirp interval, however, this does not result in a perfect synchronization [1]. There will be an overlap of any two signals, where one signal ‘leads’ and the other one ‘follows’ [2]. It is believed that male crickets vary their chirp interval, in an attempt to take the lead, because female crickets have preference in the lead cricket [3]. Following crickets can use several strategies to compete with a lead cricket, such as calling louder, increasing distance from the lead, or calling when the lead is silent [4]. Acoustic coupling is not global, though short range correlation can result in long range synchronization. In addition, ambient noise is a potential disturbance to the synchronization [5].

A Hybrid Methodology

A majority of studies concerning the synchronization behavior of crickets involve either the study of live crickets or running computer simulations [6]. In an attempt to better study this behavior, a hybrid approach is being implemented. Using mobile electronic devices to physically represent crickets, we will be able to achieve a level of control similar to a computer simulation, while more accurately representing individual crickets competing.

Each mobile device will be equipped with a microphone and speaker, allowing it to receive signals from other crickets and respond with a signal of its own. The signal will be an electronically synthesized chirp, output to the speaker. This is a good way to model an actual field study because we will be imitating real chirps.

A program will be written and executed on each device, which listens for the signal from other crickets, and upon reaching a certain threshold will respond with a signal of its own. This program will allow for each device to send its own unique signal (as crickets have unique chirps), as well as process signals as they are received and adjust the signal rate to be competitive. The mathematical model laid out by Strogatz and Mirollo will be implemented for adjusting the signal rate, adding to a crickets phase as it responds to the lead [7]. Upon responding, each device will record it’s internal system time (synced between devices), allowing for easy compilation and analysis.

Conclusion

The primary goal of this study is to achieve a better understanding of how insects synchronize, as well as observe the effects that varying conditions have on synchronization. Using multiple, electronic ‘crickets’ we will be able to accurately simulate and observe the interactions between live crickets, under controlled conditions, which result in their synchronization.

References

[1] Walker, T. J. (1969). Acoustic synchrony: two mechanisms in the snowy tree cricket. Science, (166), 891-894.

[2] Hartbauer, M., Krautzer, S., Steiner, K., & Römer, H. (2005). Mechanisms for synchrony and alternation in song interactions of the bushcricket mecopoda elongate (tettigoniidae: Orthoptera). J Comp Physiol A, (191), 175-188.

[3] Greenfield, M. D., & Roizen, I. (1993). Katydid synchronous chorusing is an evolutionarily stable outcome of female choice. Nature, (364), 618-620.

[4] Nityananda, V., & Balakrishnan, R. (2008). Leaders and followers in katydid choruses in the field: call intensity, spacing and consistency. Animal Behaviour, 76(3), 723-735.

[5] Hartbauer, M., Siegert, M. E., Fertschai, I., & Römer, H. (2012). Acoustic signal perception in a noisy habitat: lessons from synchronising insects. J Comp Physiol A, (198), 397-409.

[6] Nityananda, V., & Balakrishnan, R. (2007). Synchrony during acoustic interactions in the bushcricket mecopoda ‘chirper’ (tettigoniidae:orthoptera) is generated by a combination of chirp-by-chirp resetting and change in intrinsic chirp rate. J Comp Physiol A, (193), 51-65.

[7] Mirollo, R. E., & Strogatz, S. H. (1990). Synchronization of pulse-coupled biological oscillators. 50(6), 1645-1662.