Stochastic resonance effect on the vibratory signals of stink bugs

In this work we investigate the role of the environmental noise in the sexual communication between individuals of the Sicilian green stink bug Nezara Viridula. Our goal is to analyze the spectral features of several types of songs emitted by these insects and to find the amplitude threshold value. Below this value the signal is so weak that no neuronal activation occurs in Nezara Viridula. The presence of activation is revealed by performing directionality tests and observing the behavioral response of the insect in localizing the source of vibratory signals. Afterwards experiments are performed by using a sub-threshold signal added to a white Gaussian noise. The response of the test insect is examined for different level of noise intensity. A behavior corresponding to neuronal activation is observed when a suitable level of white noise is added to the sub-threshold signal. Our experimental measurements show the constructive interplay between the calling songs and the external-added noise. For sub-threshold signals of the calling sequence the response is subject to a non dynamical stochastic resonance phenomenon.