Stridulatory signals in triatomine communication and defence

Abstract

This chapter covers the existing evidence on stridulation in triatomines, its involvement in vibratory communication and in defence mechanisms. It starts with a brief introduction of the sensory modalities used by animals and insects, in particular triatomines, focusing on the properties of signal detection and their range. Regarding mechanical signals, it explains the characteristics of vibrational signals and how they propagate in the environment, with emphasis on substrate-borne vibrations. Furthermore, the morphology of the stridulatory organ is explained, as well as a detailed analysis of how the stridulation is produced. The organs possibly involved in signal detection are introduced, particularly those described in Hemiptera bugs. The chapter introduces the different behavioural contexts in which insects stridulate, and their occurrence in triatomines, i.e. in sexual and defensive contexts. At this point, triatomine mating is briefly described, including rejection behaviours that females can exhibit in response to the copulatory attempts of males (especially in stridulation). In addition, the chapter deals with different triatomine responses to disturbance, including stridulation and alarm pheromones. Later, comparative results between stridulation involved in sexual communication (male-deterring stridulation) and defence (disturbance stridulation), are presented. Behavioural results, as well as temporal and spectra frequency analysis of the signals, are displayed together with a table summarising the characteristics of stridulatory signals in the different species of triatomines studied so far. The chapter ends with a general discussion, and the questions still open for future research directions.