Communication Through Plants in a Narrow Frequency Window

Abstract

Different vibration-producing mechanisms determine frequency characteristics of insect communication signals transmitted through plants. Plant-dwelling stinkbugs (Heteroptera: Pentatomidae) communicate with the substrate-borne component of the vibratory emissions produced by tremulation of the whole body, tremulation of the abdomen or wings, and percussion. The main characteristics of signals produced by the mechanisms mentioned are their dominant component around 100 Hz, a different number of higher harmonics generally not exceeding 1,000 Hz and different degrees of frequency modulation. Higher-frequency components of the low-amplitude percussion signals are strongly attenuated during transmission through herbaceous plants. Stinkbug non-species-specific, low-frequency and narrow-band signal characteristics are tuned with plants as their main communication media. Herbaceous plants act as low-pass filters that optimally transmit signals of dominant frequency around 100 Hz and attenuate those above 600 Hz. Narrow-band low-frequency stinkbug vibratory signals are transmitted through stems with regularly repeated peaks of velocity minima and maxima caused by resonance. The stinkbug sensory system with underlying neuronal network effectively codes the inner frequency structure of signals produced by different mechanisms. Communication through a narrow-band frequency range on the one hand efficiently increases signal-to-noise ratio but on the other hand does not allow evolution of signals with species-specific frequency character.