Two different vibratory signals in Rhodnius prolixus (Hemiptera : Reduviidae)

In this study the substrate-borne stridulatory vibrations produced by Rhodn ius prolixus females were recorded and analysed in two different behavioura l contexts. In the context of sexual communication females spontaneously st ridulated to reject copulatory attempts performed by males. These male-dete rring stridulations were fully effective: out of 61 attempts, no copulation occurred. These stridulations consisted of short series of repetitive syll ables, each one composed by a single chirp. In the context of defensive beh aviour, bugs stridulated if they were clasped or restrained. These disturba nce stridulations consisted of long series of repetitive syllables, each on e composed by a series of short chirps and a long one. Male-deterring and d isturbance stridulations differed in their temporal pattern and frequency s pectra, having a main carrier frequency of about 1500 and 2200 Hz, respecti vely. As no differences in the inter-ridge distances along the whole stridu latory organ were found, the differences in the frequency between both sign als could be explained on the basis of a different velocity of rubbing of t he proboscis against the prosternal stridulatory organ. It was found that R . prolixus and the related species Triatoma infestans rubbed only the centr al region of the stridulatory groove (around 1/3 of the total length) to pr oduce disturbance stridulations. The results are discussed in relation to p revious work on vibrational sensitivity in R. prolixus and are also compare d with results reported for T. infestans. (C) 2000 Elsevier Science B.V. Al l rights reserved.