Time frequency analysis of the coconut rhinoceros beetle chirps

Abstract

The Coconut Rhinoceros Beetle attacks the coconut palm trees in the Pacific Region and its foraging has led to the devastion of the palm trees in Guam. The beetle is an invasive species on the island of Oahu, Hawaii, since its latent arrival in 2013. Stridulation sounds produced by the beetles have been reported with respect to mating and aggressive male behavior. Previous studies have proposed the mechanism for the stridulation and reported on some preliminary acoustic recording of the chirp for groups of beetles. However, the chrip characteristics wth respect to different behavior have not been examined extensively and also the time frequency analysis of the chirp sounds specifically or male and female beetles has been limited. In laboratory setting, the chirp characteristics are investigated with respect individual beetles in terms of pulse length and chrip duration. Time frequency analysis is used quantifiy the frequency modulation. An Empirical Mode Decompositon (EMD) provides a means of determing the instantaneous frequency and phase. Sounds of wing beats during the beetle's take off and flight are also investigated.