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At least 127 records · Page 7Linked to original sources
PubMed2003

What determines the tuning of hearing organs and the frequency of calls? A comparative study in the katydid genus Neoconocephalus (Orthoptera, Tettigoniidae).

The calls of five syntopic species of Neoconocephalus varied significantly in their spectral composition. The center-frequency of the narrow-band low-frequency component varied from 7 kHz to 15 kHz among the five species. Hearing thresholds, as determined from whole nerve recordings, did not vary accordingly among the five species but were lowest in the range from 16 kHz to 18 kHz in all five species. Iso-intensity response functions were flat for stimulus intensities up to 27 dB above threshold, indicating an even distribution of the best frequencies of individual receptor cells. At higher stimulus intensities, the intensity/response functions were steeper at frequencies above 35 kHz than at lower frequencies. This suggests the presence of a second receptor cell population for such high frequencies, with 25-30 dB higher thresholds. This receptor cell population is interpreted as an adaptation for bat avoidance. The transmission properties of the Neoconocephalus habitat (grassland) had low-pass characteristics for pure tones. Frequencies below 10 kHz passed almost unaffected, while attenuation in excess of spherical attenuation increased at higher frequencies. Considering these transmission properties and the tuning of female hearing sensitivity, call frequencies of approximately 9-10 kHz should be most effective as communication signals in this group of insects. It is discussed that the frequency of male calls is strongly influenced by bat predation and by the transmission properties of the habitat but is not strongly influenced by the tuning of the female hearing system.

Adaptation, Physiological↗
PubMed2005

The mechanics of sound production in Panacanthus pallicornis (Orthoptera: Tettigoniidae: Conocephalinae): the stridulatory motor patterns.

To examine whether sound production in katydids relies on an escapement mechanism similar to that of crickets we investigated the functional anatomy and mechanical properties of the stridulatory apparatus in the katydid Panacanthus pallicornis. Males of this species produce sustained pulses with a sharp low frequency peak of approximately approximately 5 kHz and a broad band spectrum between 15 and 25 kHz. Simultaneous recordings of movement and sound indicate that the entire stridulatory file is used for sound production and there is nearly a 1:1 correspondence between the number of cycles in a song and the number of teeth on the file. There is an overall tendency for both the spacing of teeth to increase along the file and the velocity of wing closure to increase as the scraper traverses the file. There is considerable variation, however, in the evenness of tooth spacing and in the instantaneous velocity of wing closure during sound production. The production of sustained pulses appears to depend on resonance in the right tegmen, with the left tegmen acting primarily as a damping element. This resonance is not strongly coupled to the scraper and, unlike crickets, the timing of file-scraper interactions, and therefore the phasing of energy input to wing oscillations, is variable. Similarly, the quality of the sound spectrum varies over the course of a single stridulatory wing-stroke. Based on measurements of tooth spacing on the stridulatory file and cycle-by-cycle frequency of sound output, we predicted the velocity of wing movement that would provide consistent phasing of file-scraper interactions with respect to sound-radiating wing oscillations and compared this with measurements of wing velocity. Acceleration of wing velocity during stridulation results in a closer match to the velocity required for optimal phasing during a portion of the call, and this corresponds with higher amplitudes of radiated sound and the excitation of higher order modes of vibration (evident as distinct harmonic peaks in spectrograms). Our results suggest that in katydid stridulation, the movement of the scraper along the file is not regulated by an escapement mechanism as it is in crickets. Instead, katydids that produce pure-tone songs sweep their wings over a range of velocities, within which some portion matches file tooth spacing to give optimal phasing of energy input to excite a resonance in the right tegmen.

Acoustics↗
PubMed1999

An interneurone of unusual morphology is tuned to the female song frequency in the bushcricket Ancistrura nigrovittata (Orthoptera, Phaneropteridae).

The interneurone AN5-AG7 of the duetting bushcricket Ancistrura nigrovittata has its soma in the seventh (penultimate) abdominal ganglion. Its major postsynaptic arborizations with dense thin branches of smooth appearance are found in the prothoracic ganglion. The branches terminate in the auditory neuropile, predominantly at the same location as those auditory receptors that respond best to the female song frequency. Correspondingly, AN5-AG7 responds preferentially to frequencies between 24 and 28 kHz, thereby matching the carrier frequency of the female response song quite well. At frequencies below 24 kHz, AN5-AG7 receives inhibition, which is sometimes seen as clear inhibitory postsynaptic potentials. At these frequencies, thresholds of excitatory postsynaptic potentials are considerably lower than spike thresholds. In contrast, above 20 kHz, the two thresholds match and they correspond to the behavioural threshold. The AN5-AG7 interneurone is more sensitive to soma-contralateral stimuli and it receives predominantly inhibition, but also some excitation, from the soma-ipsilateral ear. Response strength is not greatly affected by stimulus duration but shows prominent habituation. This habituation depends only weakly on intensity and frequency. Some AN5-AG7 interneurones show very small graded potentials and no spiking responses to any acoustic stimuli.

Animals↗
PubMed2001

The femur-tibia control system in a proscopiid (Caelifera, Orthoptera): a test for assumptions on the functional basis and evolution of twig mimesis in stick insects.

The extremely slow return movements observed in stick insects (phasmids) after imposed changes in posture are termed catalepsy. In the literature, catalepsy is treated as a behavioural component of the twig mimesis observed in walking stick insects. It is produced by the high gain of the velocity-sensitive component of the relevant joint control systems and by the non-linear dependency of its time constant on movement velocity. The high gain, in turn, causes the system to work close to instability, and this may have driven the evolution of gain control mechanisms. Although these statements represent plausible assumptions, based on correlated occurrence, they remain largely hypothetical like many ideas concerning evolutionary tendencies. To test these hypotheses, we studied catalepsy and the relevant properties of the femur-tibia control system in the middle and hind legs of Prosarthria teretrirostris.cf. Prosarthria teretrirostris is a proscopiid closely related to grasshoppers and locusts. With its slender, green-to-brown body and legs, it shows clear morphological twig mimesis, which has evolved independently of the well-known twig mimesis in stick insects. The animals show clear catalepsy. The main properties of femur-tibia joint control are remarkably similar between proscopiids and stick insects (e.g. the marked sensitivity to movement velocity rather than to joint position and the non-linear dependency of the time constants of response decay on movement velocity), but there are also important differences (habituation and activity-related mechanisms of gain control are absent). Together, these results validate the main concepts that have been developed concerning the neural basis and evolution of catalepsy in stick insects and its relationship to twig mimesis, while demonstrating that ideas on the role of habituation and gain control should be refined.

Animals↗
PubMed2001

Ultrasound avoidance behaviour in the bushcricket Tettigonia viridissima (Orthoptera: Tettigoniidae).

The responses of female Tettigonia viridissima to simulated bat echolocation calls were examined during tethered flight. The insects responded with three distinct behaviours, which occurred at graded stimulus intensities. At low intensities (threshold 54 dB SPL), T. viridissima responded by steering away from the sound source (negative phonotaxis). At intensities approximately 10 dB higher, beating of the hindwing was interrupted, although the insect remained in the flight posture. A diving response (cessation of the wingbeat, closure of the forewings and alignment of the legs against the body) occurred with a threshold of 76 dB SPL. Considering these thresholds, we estimate that the diving response occurs at approximately the sound amplitude at which many aerial-hawking bats first receive echoes from the insect. The other behaviours probably occur before the bat detects the insect and should therefore be interpreted as early avoidance behaviours. The repertoire of startle responses in T. viridissima, with directional and non-directional components, is similar to those of crickets and moths, but quite different from those described for another bushcricket (Neoconocephalus ensiger), which shows only a non-directional response. This supports the conclusion that bat-evasive behaviours are not conserved within the Tettigoniidae, but instead are shaped by the ecological constraints of the insects.

Animals↗
PubMed2003

Development of a toxic bait for control of eastern lubber grasshopper (Orthoptera: Acrididae).

This study assessed baits for eastern lubber grasshopper, Romalea guttata (Houttuyn). When offered a choice among several grain-based baits (rolled oats, wheat bran, oat bran, yeast, corn meal, cornflakes) and vegetable oils (canola, corn, peanut, soybean), eastern lubber grasshopper adults preferred bait consisting of wheat bran carrier with corn oil as an added phagostimulant. Other carriers were accepted but consumed less frequently. Discrimination by eastern lubber grasshoppers among oils was poor. Similarly, addition of flavorings (peppermint, anise, lemon, banana) resulted in few significant effects. The carbaryl, wheat bran, and oil bait developed in this study was effective at causing eastern lubber grasshopper mortality in field-cage studies. Significant mortality occurred even though grasshoppers had to locate dishes of bait in a large cage, and could feed on daylilies, or grass growing through the bottom of the cage, rather than on the bran flakes. Consumption of as little as a single carbaryl-treated bran flake could induce mortality, although individuals varied greatly in their susceptibility. The bait matrix developed in this study was readily consumed when in the presence of some plant species. We expect that wheat bran and corn oil bait would be most effective as protection for less preferred plants (tomato, pepper, eggplant, leek, parsley, fennel, daylily, lily of the Nile, and canna lily) because baits were readily consumed in the presence of these plants. Plants that are readily consumed in the presence of bait (preferred plants) included butter crunch lettuce, carrot, yellow squash, cauliflower, collards, green onion, chive, cucumber, cabbage, cantalope, endive, red leaf lettuce, society garlic, caladium, and amaryllis. Baits are likely to be less effective in the presence of such plants. On average, vegetables in Solanaceae (i.e., tomato, pepper, and eggplant) and Apiaceae (i.e., fennel and parsley) elicited high levels of bait-feeding activity, indicating that these vegetables were not highly preferred. The plants tested from Liliaceae, Cucurbitaceae, Asteraceae, and Brassicaceae elicited an intermediate-to-low level of bait feeding.

Animals↗
PubMed2005

Design and evaluation of traps for Idiarthron subquadratum (Orthoptera: Tettigoniidae) with farmer participation in coffee plantations in Chiapas, Mexico.

Three new types of traps designed and made by farmers were evaluated for capture of Idiarthron subquadratum Saussure & Pictet. Bag, sack, and fabric traps were compared with previously used bamboo internode traps. A participatory methodology was used involving farmer interviews and workshops to design and make the traps. Farmer participation was useful for obtaining information on perceptions, knowledge, and control activities of I. subquadratum. The bag trap captured a greater number of individuals than the bamboo and fabric traps, but its captures were similar to those of sack trap; captures were similar in bamboo, sack, and fabric traps. When captured individuals were analyzed by stage of development, no significant differences between types of traps were detected for captured adults. The number of individuals captured in the traps showed a similar trend to that counted in nocturnal sampling. A significant positive relationship was detected between numbers of adults captured and the damage of leaves and fruits. Taylor's Power Law indicates that I. subquadratum individuals were more abundant in some traps than in others. With densities greater than five individuals per trap, a smaller number of bag traps was required to estimate the same population compared with the other types of traps. Sampling procedure that used the bag traps had the lowest cost. This study shows that resource-poor coffee, Coffea arabica L., farmers had accumulated knowledge of I. subquadratum based on unpublished data and experience and that they were capable of applying this knowledge to develop an economical and more suitable technology for their conditions.

Agriculture↗
PubMed1999

Pharmacological properties of the repellent secretion of Zonocerus variegatus (Orthoptera: Prygomorphidae).

The odours of the whole body and the secretion of Zonocerus variegatus were easily recognised and perceived by human volunteers. However, the secretion odour is not related to the odour of the food plant consumed by the grasshopper. The repellency of Z. variegatus becomes more pronounced in the 6th. and adult instars whose gland lumens contain an appreciable volume of secretion. The secretion odour is so strong that even dilution does not affect its repulsiveness to humans. The secretion had pharmacological properties: it induced contraction in rat (Rattus rattus) stomach smooth muscle preparations and guinea pig (Cavia porcellus) ileum, and induced oedema formation in the rat hind paw. The secretion was not lethal to the animals used in this study, effects were temporary and recovery occurs after a short time.

Animals↗
PubMed2000

Some aspects of karyotype of Liarina (Orthoptera: Tettigoniidae, Agraeciini) from Vietnam.

Karyotypes (chromosome number and shape) of four species of the subtribe Liarina were studied. The chromosome numbers and NF (Fundamental Number) in this group of species range from 2n Male = 33 (34) to 27(30): Liaromorpha buonluoiensis 2n Male = 33 (34), Sialaiana transiens 2n Male = 29 (34), Liara tramlapensis 2n Male = 29 (32), and Anelytra (Perianelytra) propria 2n Male = 27 (30). Cyto-taxonomy analysis indicates an intensive karyotype evolution among species belonging to three different groups of the genera. Differences of karyotypes are connected with Robertsonian fusion and tandem fusion in autosomes. Additionally, C-banding distribution and location of the NORs were studied.

Animals↗
PubMed2000

Chromosome evolution in the genus Poecilimon (Orthoptera, Tettigonioidea, Phaneropteridae).

Cytotaxonomic analysis of 20 species and subspecies of the genus Poecilimon using C-banding pattern, chiasma frequency, and morphometric characteristics of the chromosomes were described. Using a cladistic analysis the chromosome data provided a basis to produce a phylogenetic tree which was compared with a tree based on morphological characters and DNA sequence data. There are important differences in the grouping of data sets to species obtained on the basis of morphology/DNA analyses and that based on chromosomes. The explanation of the differences between C-banding patterns and taxonomic proximity is probably that the C-banding pattern changes quickly as the result of the high degree of variation of constitutive heterochromatin.

Animals↗
PubMed2001

The sperm glycocalyx of Pezotettix giornai (Rossi) (Insecta: Orthoptera) after quick-freeze, deep-etching.

Mature spermatozoa of the catantopid orthopteran Pezotettix giornai are characterized by an elaborate external glycocalyx. This coating is removed during storage in spermatheca allowing preparation of sperm to their interaction with female gametes. We have studied this membrane coating in mature sperm by both conventional transmission electron microscopy and quick-freeze, deep-etching. The ultrastructural studies allowed visualization of three different domains in glycocalyx of testicular and deferent duct spermatozoa and only two in sperm cell isolated from seminal vesicles. These observations thus demonstrate that a remodeling of the male germ cell starts already during their storage in the seminal vesicle and is completed in the female genital tract. In this paper a three-dimensional (3D) model of sperm external coating is presented and discussed.

Animals↗
PubMed2001

The attraction of Zonocerus variegatus (Orthoptera: Pyrgomorphidae) to different types of lure.

Zonocerus variegatus is a common grasshopper in parts of west and equtorial Africa. The distribution in Nigeria extends from the lowland rainforest zone to the savannah in the north. The influence of lure on the behaviour of grasshopper inside cages (120 insect per cage) was investigated. Nymphs and adults of Zonocerus variegatus responded positively to intact leaves, crushed leaves and inflorescence of the common compositae weed Chromolaena odorata inside muslin bags, and intact plants. There were significant differences in the attraction recorded for starved nymphs, fed nymphs and starved adults. Attraction was more to intact leaves and is by olfaction. The increase in the attraction of starved nymphs is time dependent. Attraction to plant parts ceased after the plants were dried for 24 and 48 hours at room temperature and when plants were placed in transparent polythene bags. Gut motility and gut activity were higher during the day than at night. Nymphs, adults and egg pods placed separately inside muslin bags were not attractive to adults or nymphs.

Animals↗
PubMed2002

[Electron microscope study of haemolymph cells of Metrioptera roeselii (Orthoptera, Tettigoniidae)].

On the basis of patterns of haemocyte ultrastructure and functions at preimago and imago stages of Metrioptera roeselii, secretory cells of granulocyte type were recognized in the haemolymph. The development of granulocytes was traced starting from their formation up to cell death and destruction. The haemocytes develop as "dark" and "light" cells, differing in their functional activity, although their ultrastructure is similar. In the cytoplasm of granulocytes, granules of both mitochondrial and nuclear origin were detected. Simultaneously two processes occur in the cells--the accumulation and discharge of granules.

Animals↗
PubMed2002

Cytological and morphological differences between two species of the genus Tettigonia (Orthoptera, Tettigoniidae) from Korea.

Tettigonia ussuriana and T. dolichopoda maritima differ in the length of tegmina, details in venation, and in females in details of the subgenital plate. The two species of the genus Tettigonia have the same number and morphology of autosomes but a different morphology of the X chromosome: in T. ussuriana it is metacentric, whereas in T. dolichopoda maritima acrocentric. In both species, euchromatic zones and breaks of one or to chromatids during meiosis and mitosis in the X chromosome were observed. Additionally, B chromosomes were noted in most individuals of both species.

Animals↗