New data on bioacoustics and courtship behaviour in grasshoppers (Orthoptera, Acrididae, Gomphocerinae) from Russia and adjacent countries.

The songs of seven grasshopper species of subfamily Gomphocerinae from Russia, Ukraine, Georgia, and Kazakhstan were studied. We analysed not only the sound, but also the stridulatory movements of the hind legs to more entirely describe the songs. In Mesasippuskozhevnikovi, Chorthippusmacrocerus, and C.hammarstroemi, the legs are moved in a relatively simple pattern; four other species, Myrmeleotettixpalpalis, Stenobothrusnewskii, C.pullus, and Megaulacobothrusaethalinus demonstrate more complex leg movements. In six of the seven species studied, the courtship songs contain more sound elements than the calling songs. The highest number of courtship sound elements was found in M.palpalis and M.aethalinus. The different parts of a remarkably long stridulatory file in M.aethalinus are thought to participate in the production of different sound elements. The songs in S.newskii are shown for the first time. This species produces sound not only by common stridulation but also by wing beats. A relationship of S.newskii to some other species of the genus Stenobothrus, which are able to crepitate, is discussed. We also analyse the frequency spectra of the songs. A maximum energy of the song power spectra in six species studied lies in ultrasound range (higher than 20 kHz). In only M.aethalinus, the main peaks in the song power spectra lie lower than 20 kHz. The courtship behaviour in M.palpalis, C.macrocerus, and C.hammarstroemi was shown to include conspicuous visual display (movements of antennae, palps and the whole body).

Songs and morphology in three species of the Chorthippusbiguttulus group (Orthoptera, Acrididae, Gomphocerinae) in Russia and adjacent countries.

Songs and morphology are compared between Chorthippusmiramae (Vorontsovsky, 1928) that was previously named as C.porphyropterus and two other closely related species, C.brunneus (Thunberg, 1815) and C.maritimus Mistshenko, 1951. We compare them because the calling song of C.miramae was previously shown to have song elements similar to those of other two species. One morphological character, the length of stridulatory file, appeared to be the best character to distinguish between all three species. For C.maritimus and C.miramae, we present the morphological descriptions since they are absent in the literature. We also establish the synonymy C.maritimus = C.bornhalmi Harz, 1971, syn. n. = C.biguttuluseximius Mistshenko, 1951, syn. n. In the song analysis, we analyse not only the sound but also the leg-movement pattern, which is very helpful to find a homology between various song elements. We show that the calling song of C.miramae usually contains two elements, one element being similar to the C.brunneus calling song, and another - to the C.maritimus calling song. Despite some similarities, the calling song elements in C.miramae have some peculiarities. The courtship song of C.miramae is similar to the C.brunneus song, whereas the rivalry songs of C.miramae comprise both the maritimus-like elements and the unique ones. C.miramae generally demonstrates a richer song repertoire than the other two species.

Songs and morphology in grasshoppers of the Stenobothrus eurasius group (Orthoptera: Acrdidae: Gomphocerinae) from Russia and adjacent countries: clarifying of taxonomic status.

On the basis of the song and morphological analyses, we revised the status of the subspecies Stenobothrus eurasius eurasius Zubowsky, 1898, and S. eurasius hyalosuperficies Vorontsovskii, 1927. The status of the subspecies S. eurasius hyalosuperficies Vor. has been changed to the species level. The most striking difference between S. eurasius and S. hyalosuperficies lies in the song parameters. The calling songs differ not only in temporal parameters but are also produced by different mechanisms. S. eurasius generates calling songs by common leg stridulation, whereas S. hyalosuperficies produces sound by wing clapping. The courtship songs of both species are complex (contain several elements) and very different in temporal structure. The morphological differences between the two species are not as striking as the differences in bioacoustics: we found the only differences in the hind wing venation. At the same time, we suggest these differences to be important since they might be due to different mechanisms of sound production. We revised the ranges of the two species on the territory of Ukraine, Russia and Kazakhstan. We also reviewed the type localities of S. eurasius Zub. and designated lectotype and paralectotype of this species.

Contributions to the study of the grasshopper (Orthoptera: Acrididae: Gomphocerinae) courtship songs from Kazakhstan and adjacent territories.

Male courtship songs of 9 grasshopper species of Gomphocerinae from Kazakhstan and Orenburg region and Altai Republic of Russia were studied. We analyzed not only the sound, but also the stridulatory movements of the hind legs to more entirely describe the songs. We also analyze the frequency spectra of the songs and the whole visual display during courtship. The courtship songs of three species, Stenobothrus miramae, Chorthippus dubius and Ch. angulatus, were studied for the first time. In four species, Omocestus haemorrhoidalis, O. petraeus, Myrmeleotettix pallidus, Ch.karelini, we found certain differences in temporal pattern of the courtship songs in comparison with the previous data on the respective species from other regions. In five species, O. viridulus, S. miramae, M. pallidus, Ch. dubius and Ch. karelini, various parts of elaborate courtship songs differed in the carrier frequency. In four species, O. haemorrhoidalis, O. petraeus, M. pallidus and Ch. dubius, the dominant frequencies of the courtship song were shown to lie in the range higher than 20 kHz. The conspicuous movements of antennae and legs during courtship were studied in M. pallidus, S. miramae and Gomphocerus sibiricus.

Variation in complex mating signals in an "island" hybrid zone between Stenobothrus grasshopper species.

Two grasshopper species Stenobothrus rubicundus and S. clavatus were previously shown to meet in a narrow hybrid zone on Mount Tomaros in northern Greece. The species are remarkable for their complex courtship songs accompanied by conspicuous movements of antennae and wings. We analyzed variations in forewing morphology, antenna shape, and courtship song across the hybrid zone using a geographic information system, and we documented three contact zones on Mount Tomaros. All male traits and female wings show abrupt transitions across the contact zones, suggesting that these traits are driven by selection rather than by drift. Male clines in antennae are displaced toward S. clavatus, whereas all clines in wings are displaced toward S. rubicundus. We explain cline discordance as depending on sexual selection via female choice. The high covariance between wings and antennae found in the centers of all contact zones results from high levels of linkage disequilibria among the underlying loci, which in turn more likely results from assortative mating than from selection against hybrids. The covariance is found to be higher in clavatus-like than rubicundus-like populations, which implies asymmetric assortative mating in parental-like sites of the hybrid zone and a movement of the hybrid zone in favor of S. clavatus.

Recognition of variable courtship song in the field cricket Gryllus assimilis.

We analyzed the courtship song of the field cricket Gryllus assimilis. The song comprises two elements: groups of ca. 10 pulses (chirps) with low fundamental frequency (3.5-3.7 kHz) alternating with high-frequency (15-17 kHz) pulses (ticks) that usually occur as doublets. Some elements of courtship song are quite variable (high coefficient of variation) both within and between males, whereas others are more stereotypical. In experiments with playback of synthesized courtship songs, we studied the importance of several song parameters for mating success, which we evaluated as the probability with which females mounted muted, courting males. Altering some features that show little variability, such as chirp-pulse rate or carrier frequency of ticks, resulted in significant decreases in mounting frequency, consistent with the notion that trait values showing little variability are constrained by stabilizing selection exerted by females. However, alteration of one invariant trait, the occurrence of both song components, by omitting either component from test songs only slightly affected female responsiveness. Alteration of a variable song trait, the number of ticks per song phrase, had no effect on female response rate, thus failing to provide support for the idea that variable traits provide a substrate for sexual selection. An unusual characteristic feature of the song of G. assimilis is that chirp pulses often contain substantial high-frequency power, and indeed may entirely lack power at the fundamental frequency. Playback experiments showed that such songs are, nevertheless, behaviorally effective. To understand the neural basis for this, we recorded the responses of the two principal ascending auditory interneurons of crickets, AN1 and AN2. Our results suggest that the frequency selectivity of the neurons is sufficiently broad to tolerate the spectral variability of courtship chirps.

Allatostatin-like immunoreactivity in the abdomen of the locust Schistocerca gregaria.

A polyclonal antibody against allatostatin 1 (AST-1) of cockroach Diploptera punctata was used to investigate the distribution of AST-like immunoreactivity within the abdomen of the locust, Schistocerca gregaria. In the abdominal ganglia, AST-like immunoreactivity was found in both cell bodies and neuropile. In ganglia 6 and 7, staining was found in serial homologous cell bodies in anterior dorsolateral and dorsomedial, and posterior ventrolateral and ventromedial locations. In the terminal ganglion, the numerous immunoreactive somata were smaller in size than those in the unfused ganglia. The combination of backfill experiments with immunocytochemistry showed that, in abdominal ganglion 7, one neuron of the ventromedian cell body cluster and two of the ventrolateral cluster innervated the oviduct, which itself was covered with a dense mesh of AST-immunoreactive varicosities. Combining electron microscopy with immunohistochemistry revealed AST-like immunoreactivity in dense-core vesicles located in neurohaemal-like terminals lacking structures normally found in synapses. A mesh of AST-immunoreactive varicosities was also found on the muscles of the spermatheca and the spermathecal duct. In addition, a mesh of strongly stained varicosities was present in the distal perisympathetic organs (neurohaemal organs in the abdomen) and on the lateral heart nerves (a putative neurohaemal release zone). These data indicate that AST is an important neuroactive substance that is probably involved in multiple tasks in the control of the locust abdomen.