Motor and mechanical bases of the courtship call of the male treehopper Umbonia crassicornis

Functional Diversity of Vibrational Signaling Systems in Insects

Communication by substrate-borne mechanical waves is widespread in insects. The specifics of vibrational communication are related to heterogeneous natural substrates that strongly influence signal transmission. Insects generate vibrational signals primarily by tremulation, drumming, stridulation, and tymbalation, most commonly during sexual behavior but also in agonistic, social, and mutualistic as well as defense interactions and as part of foraging strategies. Vibrational signals are often part of multimodal communication. Sensilla and organs detecting substrate vibration show great diversity and primarily occur in insect legs to optimize sensitivity and directionality. In the natural environment, signals from heterospecifics, as well as social and enemy interactions within vibrational communication networks, influence signaling and behavioral strategies. The exploitation of substrate-borne vibrational signaling offers a promising application for behavioral manipulation in pest control.

On the morphology and evolution of cicadomorphan tymbal organs

Cicadas and many of their relatives (Hemiptera: Cicadomorpha) generate vibroacoustic signals using tymbal organs located on their first two abdominal segments. Although tymbals are well-studied in Cicadidae, their systematic distribution in other Cicadomorpha and their possible homologies to the vibroacoustic mechanisms of other Hemiptera have been debated for more than a century. In the present study, we re-examine the morphology of the musculoskeletal system of cicadomorphan vibroacoustic organs, and we document their systematic distribution in 78 species drawn from across the phylogeny of Cicadomorpha. We also compare their morphology to the recently-described snapping organ of planthoppers (Fulgoromorpha). Based on the structure and innervation of the metathoracic and abdominal musculoskeletal system, we find that several key elements of cicadomorphan vibroacoustic organs that have previously been assigned to the first abdominal segment in fact belong to the second. We find that tymbal organs are nearly ubiquitous in Cicadomorpha, and conclude based on their phylogenetic distribution, that they are likely to be synapomorphic. The unusual tymbal-like organs of the Deltocephalinae and Typhlocybinae, represent derived modifications. Finally, we propose a standardised terminology for sternal components of the cicadomorphan vibrational organs, which can be used in future taxonomic descriptions.

The flightin gene is necessary for the emission of vibrational signals in the rice brown planthopper (Nilaparvata lugens Stǻl)

In duet-based courtship, species- and sex-specific vibrational signals enable animals to identify the species and sex of the singer and also provide the necessary information with which to locate a partner. Substrate-borne communication has been described in a wide variety of insects. Here, we focus on the gene necessary for the emission of male vibrational signals and whether the male song fulfills such a functional role in the mating system of the brown planthopper (BPH, Nilaparvata lugens). We generated mute BPH adult males via RNA interference (RNAi) of the flightin gene, which encodes a myosin-binding protein expressed exclusively in the dorsal longitudinal muscle (DLM) in the basal two abdominal segments used for driving the vibration of the male-specific tymbal structure in short-winged (brachypterous) BPH adults. Transmission electron microscopy (TEM) observation showed that flightin knockdown disrupted the normal sarcomere structure of the abdominal DLM. No courtship song could be detected in the brachypterous males after RNAi treatment. Behavior and competition trials showed that the lack of male courtship songs prolonged copulation latency and even caused female rejection. Unexpectedly, the mute males exhibited greater competitiveness when competing against normal males.

On the spot: utilization of directional cues in vibrational communication of a stink bug

Although vibrational signalling is among the most ancient and common forms of communication, many fundamental aspects of this communication channel are still poorly understood. Here, we studied mechanisms underlying orientation towards the source of vibrational signals in the stink bug Nezara viridula (Hemiptera, Pentatomidae), where female vibrational song enables male to locate her on the bean plant. At the junction between the main stem and the leaf stalks, male placed his legs on different sides of the branching and orientation at the branching point was not random. Analyses of signal transmission revealed that only a time delay between the arrival of vibrational wave to receptors located in the legs stretched across the branching was a reliable directional cue underlying orientation, since, unexpectedly, the signal amplitude at the branching point was often higher on the stalk away from the female. The plant and the position of the vibrational source on the plant were the most important factors influencing the unpredictability of the amplitude cue. Determined time delays as short as 0.5 ms resulted in marked changes in interneuron activity and the decision model suggests that the behavioural threshold is in the range between 0.3 and 0.5 ms.