Temporal Processing of Vibratory Communication Signals at the Level of Ascending Interneurons in Nezara viridula (Hemiptera: Pentatomidae)

Abstract

During mating, males and females of N. viridula (Heteroptera: Pentatomidae) produce sex- and species-specific calling and courtship substrate-borne vibratory signals, grouped into songs. Recognition and localization of these signals are fundamental for successful mating. The recognition is mainly based on the temporal pattern, i.e. the amplitude modulation, while the frequency spectrum of the signals usually only plays a minor role. We examined the temporal selectivity for vibratory signals in four types of ascending vibratory interneurons in N. viridula. Using intracellular recording and labelling technique, we analyzed the neurons' responses to 30 pulse duration/interval duration (PD/ID) combinations. Two response arrays were created for each neuron type, showing the intensity of the responses either as time-averaged spike counts or as peak instantaneous spike rates. The mean spike rate response arrays showed preference of the neurons for short PDs (below 600 ms) and no selectivity towards interval duration; while the peak spike rate response arrays exhibited either short PD/long ID selectivity or no selectivity at all. The long PD/short ID combinations elicited the weakest responses in all neurons tested. No response arrays showed the receiver preference for either constant period or duty cycle. The vibratory song pattern selectivity matched the PD of N. viridula male vibratory signals, thus pointing to temporal filtering for the conspecific vibratory signals already at level of the ascending interneurons. In some neurons the responses elicited by the vibratory stimuli were followed by distinct, regular oscillations of the membrane potential. The distance between the oscillation peaks matched the temporal structure of the male calling song, indicating a possible resonance based mechanism for signal recognition.

Duration Tuning across Vertebrates

“…Invertebrate duration selectivity for vibratory signals has also been found in ascending interneurons of insects (Zorović, 2011). Our results support the hypothesis that neural mechanisms of duration selectivity may be shared across vertebrates.…”

Stink Bug Communication with Multimodal Signals Transmitted through Air and Substrate

“…Interneurons of one group are tuned to frequencies below 100 Hz, and those of the other to a broader frequency range, characteristic of the receptor neuron, responding best around 200 Hz. Zorović [109] confirmed that filtering of temporal characteristics of N. viridula vibratory communication signals occurs at the periphery of the species' central nervous system at the level of four different types of the ascending ventral cord neurons.…”

Rivalry between Stink Bug Females in a Vibrational Communication Network

“…The repertory of stinkbug female rivalry interactions observed as synchronized signalling, exchange of different types of calling song signals and emission of the female rival song is more complex than the one reported for male/male stink bug interactions. In the latter interactions, males express rivalry only by exchanging of rival song pulses in a-b-a-b sequence (Čokl et al 2000, 2011Blassioli-Moraes et al 2005;Bagwell et al 2008).…”

“…Songs have been determined according to the mating behavioral context as calling, courtship, copulatory, repelling and rival songs. The latter were identified and described only for males competing to copulate with the same female (Čokl et al 2000, 2011Blassioli-Moraes et al 2005;Bagwell et al 2008).…”