A Comunicação Entre Insetos Através de VibraçõesRESUMO -A comunicação através de vibrações originárias do substrato tem sido reconhecida há muito tempo, mas tem recebido muito menos atenção que a comunicação através do som propagado pelo ar. Recentemente, entretanto, tem se tornado cada vez mais claro o papel crucial que sinais vibratórios desempenham na comunicação em muitos grupos de insetos, o que motivou essa revisão suscinta. Sinais vibracionais estão relacionados ao comportamento sexual, de alarme e de defesa, e são em geral usados para mediar ações coordenadas em grupo e interações sociais complexas. Para insetos pequenos esses sinais representam um custo energético mínimo, com alcance máximo, e que não são percebidos facilmente por predadores e por parasitóides em potencial. Sinais originários dos substrato são produzidos por diversos métodos e detectados por receptores presentes nas seis pernas. O comportamento de corte do percevejo verde, Nezara viridula (L.) (Hemiptera: Pentatomidae) é analisado como um modelo representativo na ilustração de alguns mecanismos importantes na comunicação vibracional em insetos. Sinais vibratórios são específicos das espécies e de sexos, os quais são produzidos durante a corte e que são adequados para serem transmitidos pelas plantas, contendo informações relevantes sobre a espécie e o sexo do organismo emissor, bem como informações de onde localizar o parceiro. O papel de sinais originados do substrato, os quais são únicos para cada espécie, faz com que os estudos em sinais vibracionais sejam uma importante ferramenta para resolver problemas taxonômicos. PALAVRAS-CHAVE: Comunicação vibracional, vibração do substrato, comportamento, Nezara viridulaABSTRACT -Communication through substrate-borne vibrations has for long been recognized but in comparison with air-borne sound it has received very little attention. However, in recent years it has become increasingly clear that vibrational signals play a crucial role in communication in many insect groups and we provide a short overview. Vibrational signals are related to sexual behavior, alarm and defensive behavior and are often used to mediate coordinated group actions and complex social interactions. For small insects they are probably the least costly and most far-reaching signals for intraspecific communication and also not easily perceived by a potential predator or parasitoid. Substrateborne signals are produced by diversed methods and detected by sensitive receptors in all six legs. The courtship behavior of the southern green stink bug Nezara viridula (L.) (Hemiptera: Pentatomidae) is taken as a representative model in illustrating some principal mechanisms of vibrational communication in insects. Species and sex specific vibrational signals produced during the courtship are well suited for propagation through plants and to transmit the relevant information about the species and sex of the sender as well as provide the directional cue for locating the mate. The role of substrate-borne signals as a part of the specifi...

Mating behaviour of Scaphoideus titanus Ball, the vector of the grapevine disease Flavescence dorée, was investigated in order to determine the role of substrate-borne vibrational signals in intra-specific communication and pair formation. Vibrational signals were recorded from grapevine leaves with a laser vibrometer. Signalling activity of single males changed throughout the day and the peak in activity was associated with twilight and early night when 'call and fly' behaviour was observed. Pair formation began with the spontaneous emission of male signals. The male calling signal consisted of a single series of pulses, partially accompanied with a 'rumble'. The male courtship phrase consisted of four consecutive sections characterized by two sound elements, pulse and 'buzz'. Female vibrational signals were emitted only in response to male signals. The female response was a single pulse that closely resembled male pulses and was inserted between pulses within the male signals. All recorded vibrational signals of S. titanus have a dominant frequency below 900 Hz. A unique feature of vibrational communication in S. titanus is well-developed intrasexual competition; males may use alternative tactics, in the form of disturbance signals, or silently approach duetting females (satellite behaviour). While the male-female duet appears to be essential for successful localization of females and copulation, it is also vulnerable to, and easily disrupted by, alternative tactics like masking.

Vibratory signals of plant-dwelling insects, such as land bugs of the families Cydnidae and Pentatomidae, are produced mainly by stridulation and/or vibration of some body part. Signals emitted by the vibratory mechanisms have low-frequency characteristics with a relatively narrow frequency peak dominant around 100 Hz and differently expressed frequency modulation and higher harmonics. Such spectral characteristics are well tuned to the transmission properties of plants, and the low attenuation enables long-range communication on the same plant under standing wave conditions. Frequencies of stridulatory signals extend up to 10 kHz. In some groups, vibratory and stridulatory mechanisms may be used simultaneously to produce broadband signals. The subgenual organ, joint chordotonal organs, campaniform sensilla and mechanoreceptors, such as the Johnston's organ in antennae, are used to detect these vibratory signals. Species-specific songs facilitate mate location and recognition, and less species-specific signals provide information about enemies or rival mates.

Genetic variation in the southern green stink bug Nezara viridula (Linnaeus) from 11 geographically separated sampling locations (Slovenia, France, Greece, Italy, Madeira, Japan, Guadeloupe, Galapagos, California, Brazil and Botswana) was studied by sequencing 16S and 28S rDNA, cytochrome b and cytochrome c oxidase subunit I gene fragments and random amplified polymorphic DNA (RAPD) analysis. Sequencing revealed 11 distinct haplotypes clustering into lineages A, B and C. Lineage C was characteristic for a single analysed specimen from Botswana. Lineage B was detected in Japan, and it probably arose in Asia. Haplotypes of European and American specimens belonged to lineage A; specimens from France, Slovenia, Madeira and Brazil shared highly similar haplotypes (>99%) from subgroup A1, while all the specimens from Greece, California, Galapagos and Guadeloupe shared a haplotype from subgroup A2. RAPD data were more variable but consistent with mtDNA sequences, revealing the same clustering. They separated the Botswanian specimen from Japanese specimens and from a group of more closely related specimens from Europe and America. Sequence and RAPD results both support the African origin of N. viridula, followed by dispersal to Asia (lineage B) and, more recently, by expansion to Europe and America (lineage A). RAPD analysis revealed two highly supported subgroups in Japan, congruent with mtDNA lineages A2 and B, suggesting multiple colonization of Japan. Invariant sequences at the 28S rDNA combined with other results do not support the hypothesis that cryptic (sibling) species exist within the populations investigated in this study.

Scaphoideus titanus Ball (Hemiptera: Cicadellidae: Deltocephalinae) is the vector of the grapevine disease Flavescence dorée. In S. titanus the male–female duet (MFD), based on species‐specific vibrational signals, is essential for successful copulation. The female reply within a duet is a single pulse that is coupled with the male pulse with constant latency. It has been shown that a rival male can interrupt an existing duet by emitting disruptive noise signals. We tested whether the reproductive behaviour of S. titanus can be disrupted by the playback of intra‐specific and synthesized vibrational signals. Tested males responded to the playback of an MFD with typical rivalry behaviour. Such behaviour includes silent search for a duetting female (satellite behaviour) and/or emission of disruptive signals. These signals were emitted either after exchange of male–female pulses or after two male pulses coupled by latency corresponding to the female response window. The onset of male disruptive signals overlapped with a female pulse. We suggest that the intruder’s disruptive signals can mask the female reply and confuse courting males. Playback of disruptive vibrational signals reduced the level of male calling and interrupted an established MFD that consequently resulted in a significantly reduced number of copulations. These results indicate that the vibrational communication channel is open to interference either from abiotic environmental noise or from signals produced by sexual competitors or heterospecifics. The present study also suggests that a detailed understanding of leafhopper behaviour is essential for trying new approaches in the development of more environmentally friendly control practices.