Vibrational communication in insects: entangled and invisible networks on plants

The communication by means of substrate-borne vibrations is the most spread channel of communication in arthropods, although at the same time the least studied and understood. In mating communication, vibrational signals allow the expression of many behavioural traits that also can constitute solid elements of individual fitness. A species can produce a more or less wide repertoire of signals, which are characterized by certain features (spectral and temporal) that eventually drive the mate choice and, consequently,the reproductive success. Signals are also decisive in intra-sexual competition (e.g. malemale rivalry), in inter-species or antagonistic interactions (e.g. predators or parasitoids that eavesdrop mating signals) and are affected by substrate characteristics (e.g. hostplant features). All these vibrational signals create a complicated network that travels along the substrate even for several meters. Any individual has its own Active Space Network (ASN), thanks to which it can interact with the surrounding world. The ASN can be defined as the cladogram-like substrate network covered by an active signal that spreads from a vibrational source. To describe and understand the many ASN occurring on the plants is a hard task and a researcher must respond to many questions. In first instance, he/she has to “learn” a signal, to distinguish between species-specific and individual-specific features, to insert it into the appropriate context, both behavioural and environmental. Only from the knowledge of the behaviour and the related communication system of a species it will be possible to set a reliable strategy of crop protection.