Australian Field Cricket Research Articles

Multisegmental analyses of acoustic startle in the flying cricket (Teleogryllus oceanicus): kinematics and electromyography.

Tethered, flying Australian field crickets (Teleogryllus oceanicus) stimulated with ultrasound respond with a rapid, short-latency turn from the sound source. We analyzed the kinematics of two behavioral components of this acoustic startle response and recorded electromyograms from the muscles involved in producing them. The two behavior patterns studied were the swing of the metathoracic leg, which has been shown to elicit a short-latency turn, and a lateral swing of the antennae, for which a direct role in steering has not been demonstrated. The kinematic data showed that when a pulse of ultrasound was presented to one side of the animal (1) the contralateral metathoracic leg abducted and elevated, while the ipsilateral leg remained in place, (2) both antennae swung laterally, but the contralateral antenna moved farther than the ipsilateral antenna, (3) increases in stimulus intensity elicited larger movements of the leg and contralateral antenna, while the ipsilateral antenna showed little sensitivity to stimulus intensity, and (4) for the leg, the latency to the onset of the swing decreased and the duration of the movement increased with increasing stimulus intensity. Electromyograms were recorded from the leg abductor M126 and two antennal muscles: the medial scapo-pedicellar muscle M6 and the lateral scapo-pedicellar muscle M7. M7 moves the antenna laterally, M6 moves it medially. Upon stimulation with ultrasound (1) both M126 and M7 showed increasing spike activity with increasing intensity of the ultrasound stimulus, (2) M126 showed a decrease in latency to the first spike and an increase in the duration of spike activity with increasing stimulus intensity, (3) latencies for M6 and M7 were not correlated with stimulus intensity, but M7 had significantly shorter latencies than M6 and the contralateral M7 had significantly shorter latencies than the ipsilateral M7, and (4) the ipsilateral M126 spiked in response to ultrasound in 6 of the 10 animals tested. In these cases, however, latency to the first spike was substantially longer, and the spike frequency was lower than for the muscle's response to contralateral stimuli. We attempt to correlate these electromyogram data with the kinematic data and relate them to the relevance of the two behavior patterns to the execution of an escape response.

Habituation of the ultrasound-induced acoustic startle response in flying crickets

The ultrasound-induced negative phonotactic response of tethered, flying Australian field crickets habituates to repeated stimuli. Using the magnitude of the metathoracic leg's swing during a series of ultrasonic stimuli as a measure of habituation, we show that: (1) the response declines exponentially; (2) the response recovers spontaneously; (3) repeated trials produce more rapid and stronger habituation; (4) successive stimuli presented more rapidly produce more rapid and stronger habituation; (5) a weaker stimulus intensity produces more rapid and stronger habituation; (6) the habituation shows stimulus generalization (i.e. the response is similar for different ultrasonic frequencies); (7) a novel stimulus produces dishabituation; and (8) the effect of the dishabituating stimulus habituates after repeated trials. These findings place habituation of cricket negative phonotaxis in the context described for habituation in mammals.

Leg-Induced Steering in Flying Crickets

ABSTRACT Over the past 50 years, researchers have speculated that flying insects use their legs as part of the steering mechanism. This hypothesis developed from observing that insects making a right turn, for example, swing their right metathoracic and sometimes mesothoracic leg in the direction of the turn. Several insects exhibit this behaviour, including crickets (Moiseff et al. 1978), locusts (Gettrup and Wilson, 1964; Dugard, 1967; Baker, 1979; Cotter, 1979; Taylor, 1981), flies (Hollick, 1940; Götz et al. 1979; Nachtigall and Roth, 1983) and bugs (Govind and Burton, 1970; Govind, 1972). In locusts, Camhi (1970) noted that the inside metathoracic leg (i.e. on the same side as the turn) moves out from the body and into the path of the hindwing during yaw steering; however, the aerodynamic effect was untested. Here we demonstrate that in the Australian field cricket (Teleogryllus oceanicus) the metathoracic leg produces a significant aerodynamic effect on yaw steering by impeding the downstroke of the hindwing on the inside of the turn.

Effect of Variation in Form on the Cost of Terrestrial Locomotion

The mass-specific minimum cost of terrestrial locomotion (Cmin) decreases with an increase in body mass. This generalization spans nearly eight orders of magnitude in body mass and includes two phyla. The general relationship between metabolic cost and mass is striking. However, a significant amount of unexplained interspecific variation in Cmin exists at any given body mass. To determine how variation in morphology and physiology affects metabolic energy cost, we measured the oxygen consumption of three comparably sized insects running on a miniature treadmill; the American cockroach Periplaneta americana, the caterpillar hunting beetle Calosoma affine and the Australian field cricket Teleogryllus commodus. Steady-state oxygen consumption (VO2ss) increased linearly with speed. Cmin was similar for crickets and cockroaches (8.0 and 8.5 ml O2 g-1km-1, respectively), but was substantially lower for beetles (4.6 ml O2 g-1km-1). The predicted value of Cmin for all three insects was within the 95% confidence intervals of the Cmin versus body mass function. However, the 95% confidence intervals extend approximately 2.5-fold above and 40% below the regression line, making the variation at any given body mass nearly sixfold. Normalizing for the rate of muscle force production by determining the metabolic cost per stride failed to account for the interspecific variation in the cost of locomotion observed in the three insects. Ground contact costs (i.e. VO2ss multiplied by leg contact time during a stride) in insects were similar to those measured in mammals (1.5-3.1 J kg-1) and were independent of speed, but did not explain the interspecific variation in the cost of locomotion. Muscles of the caterpillar hunting beetle may have a greater mechanical advantage than muscles of the Australian field cricket and American cockroach. Variation in musculo-skeletal arrangement, apart from variation in body mass, could translate into significant differences in the minimum cost of terrestrial locomotion.

Ultrasound-induced yaw movements in the flying Australian field cricket (Teleogryllus oceanicus)

An ultrasonic stimulus induced negative phonotactic steering in the yaw axis of tethered, flying Australian field crickets. The forewings, hindwings and twisting of the thorax generated the forces which induced the yaw turn. However, abdominal ruddering did not contribute to yaw turns. Each aspect of the yaw steering response depended upon the stimulus intensity. At higher ultrasonic intensities, the magnitude and average angular velocity increased while the latency of the yaw turn decreased. Each of these factors varied in a graded manner, revealing that this behavior is more complex than a simple reflex.

The role of ocelli in circadian singing rhythms of crickets

ABSTRACT. . There is a direct quantitative relationship between the free‐running period (r) of the circadian stridulation rhythm of male Australian field crickets, Teleogryllus commodus (Walker), and the intensity of the constant light conditions. Both T. commodus and the house cricket, Acheta domesticus (L.), show free‐running periods of the singing rhythm of c. 24 h when the light intensity is 0.00025 lux. In both species the severance of the three ocellar nerves significantly slows the circadian period which is indicative of a reduced perception of the available light intensity. To test whether this period reduction is a peripheral or a central effect, electro‐retinograms (ERGs) were recorded from compound eyes of male T. commodus with the ocelli fully functional, then occluded, and then uncovered. The size of the compound eye ERG is reduced by 20% with ocellar occlusion and can subsequently be fully restored to the intact level, which indicates that the ocellar effect is a peripheral one. Intensified CoCl2 fills reveal one neurone in A. domesticus and two in T. commodus which travel from the lateral ocellar nerve out into the ipsilateral optic lobe of the compound eye. These neurones all terminate in or distal to the lobular neuropile. The data are interpreted to indicate a role for ocelli in modulating the light intensity perception of the compound eye. The final effect of the ocellar afferents is at a peripheral level prior to the input of the visual information to the optic lobe circadian pacemaker. Hence ocelli play an indirect role in circadian rhythmicity, augmenting the sensitivity of the primary photoreceptors to better perceive photic entrainment signals.

Circadian timing of cricket calling song: a clock persisting from nymphs to adults

ABSTRACT. Male Australian field crickets (Teleogryllus commodus, Walker) reared in LD 12:12 h were transferred to LL at different developmental stages and the timing of their circadian calling song rhythm was analysed in regard to the previous zeitgeber. The phase settings for the onset and end of activity were similar in crickets experiencing the LD/LL transition: (i) 3–52 days after the final moult, (ii) within 24 h before the final moult, or (iii) 1–10 days before the final moult. For all groups the results reveal entrainment of the circadian mechanism at the last LD, thus excluding age‐related differences. The rhythms of crickets, transferred from LD to LL as larval instars and also exposed to a reduced temperature (5–8oC) during their last night, were delayed by about 11 h, an effect similar to that in adult crickets after a comparable cold exposure (Loher & Wiedenmann, 1981).The results are interpreted showing that the circadian control of (the adult's) calling song already functions in the previous (non‐singing) larval stages. Since the rhythmicity continued through moults and sexual maturation, it is concluded that the control centres regulating those physiological processes (e.g. pars intercerebralis, corpora allata) are not essential to the basic circadian mechanism.

Commissural ring nerve: A female-specific neurosecretory tract supplied by bifurcating median neurons in the cockroach Periplaneta americana (L.) and the cricket Teleogryllus commodus (Walker)

In the American cockroach, Periplaneta americana, and the Australian field cricket, Teleogryllus commodus, the two nerves supplying the bases of the cerci are joined by a branch that crosses behind the last abdominal ganglion. This commissural ring nerve is restricted to females, and it contains many axons filled with granular and agranular vesicles. The axons stem from somata located within the ganglion. There are one (Periplaneta) or two (Teleogryllus) groups of median neurons with bilaterally symmetrical bifurcations, and a group of postero-ventral neurons on each side. In T. commodus, these neurons are distinct from others associated with the cerci. In the two species, the ring nerve neurons contribute to a neuropile near the root of each cereal nerve. The bifurcating median neurons arborize on both sides before entering the ring nerve, while the postero-ventral ones branch more extensively ipsilateral to their somata. The possibilities are discussed that the bifurcating neurons may be homologous to dorsal unpaired median neurons, and that the ring nerve may be a neurohemal area.

Kinematic and aerodynamic aspects of ultrasound-induced negative phonotaxis inflying Australian field crickets (Teleogryllus oceanicus).

Negative phonotaxis is elicited in flying Australian field crickets, Teleogryllus oceanicus, by ultrasonic stimuli. Using upright tethered flying crickets, we quantitatively examined several kinematic and aerodynamic factors which accompany ultrasound-induced negative phonotactic behavior. These factors included three kinematic effects (hindwing wingbeat frequency, hindwing elevation and depression, and forewing tilt) and two aerodynamic effects (pitch and roll). 1. Within two cycles following a 20 dB suprathreshold ultrasonic stimulus, the hindwing wingbeat frequency increases by 3-4 Hz and outlasts the duration of the stimulus. Moreover, the relationship between the maximum increase in wingbeat frequency and stimulus intensity is a two-stage response. At lower suprathreshold intensities the maximum wingbeat frequency increases by approximately 1 Hz; but, at higher intensities, the maximum increase is 3-4 Hz. 2. The maximum hindwing elevation angle increases on the side ipsilateral to the stimulus, while there was no change in upstroke elevation on the side contralateral to the stimulus. 3. An ultrasonic stimulus affects forewing tilt such that the forewings bank into the turn. The forewing ipsilateral to the stimulus tilts upward while the contralateral forewing tilts downward. Both the ipsilateral and contralateral forewing tilt change linearly with stimulus intensity. 4. Flying crickets pitch downward when presented with a laterally located ultrasonic stimulus. Amputation experiments indicate that both the fore and hindwings contribute to changes in pitch but the pitch response in an intact cricket exceeds the simple addition of fore and hindwing contributions. With the speaker placed above or below the flying cricket, the change is downward or upward, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Egg‐laying in response to prostaglandin injections in the Australian field cricket, Teleogryllus commodus

ABSTRACT. We report the effects of prostaglandin (PG) injection on egg‐laying by sexually mature virgin crickets, Teleogryllus commodus Walker. High egg‐laying activity is associated with PGE1 PGE2, 6‐keto‐PGE1 and 15‐keto‐PGE2, compounds that share the basic prostanoid backbone (C20 substituted fatty acid, 5 membered ring, a 7‐ and an 8‐carbon aliphatic chain), and 9‐keto, 11‐hydroxyl ring substitutions. PGs without these ring features and other compounds that lack the prostanoid backbone have no or only intermediate egg‐laying effects. Adding oxygen functionalities or an aliphatic double bond tends to increase egg‐laying activity. Hence, 15‐keto‐PGF2 and TxB2, both of which have an additional backbone oxygen compared with their less active analogues, are highly active compounds. Two of the most active PGs, 15‐keto‐PGE2 and 15‐keto‐PGE2α, are the products of inactivating metabolism in mammalian systems, describing a fundamental difference in PG biochemistry with respect to mammals and insects.

Circadian locomotory rhythm and the influence of moulting in Australian field cricket nymphs

ABSTRACT. Evidence is presented for a circadian control of locomotory activity in the larval stadia of the cricket, Teleogryllus commodus Walker. Under light—dark cycles (LD), maximal activity occurs around the L/D transition and/or in the hours preceding it. Free‐running rhythm patterns longer than 24 h are observed in constant light. Re‐entrainment to phase advances in the LD cycle is also accompanied by several transient cycles. However, free‐running rhythms under constant darkness or transients when exposed to LD cycle delays were not found. LD cycles during the eighth stadium set the phase of a free‐running rhythm in the adult, even if the nymph does not show a rhythm. Nymphal activity is often erratic and is disrupted periodically by the moulting cycle, but moulting does not interrupt the operation of the circadian system. The daily timing of the moult itself is not under circadian control.

De novo biosynthesis of prostaglandins by the australian field cricket, Teleogryllus commodus

1. The accumulation and metabolism of certain polyunsaturated fatty acids by testes from the Australian field cricket, Teleogryllus commodus, are described. Testes accumulated a substantial proportion (about 16%) of label from radioactive C20:3n6 that was injected into the haemocoel. Fifty percent of the label accumulated by testes was associated with the phospholipid fraction, whereas in the remainder of the body 30% was incorporated into the phospholipid fraction. 2. Prostaglandins (PG) E 1, E 2 and F 2α were quantified in extracts of the testes of adult insects by radioimmunoassay. 3. Label from injected radioactive C18:2n6, C20:3n6 and C20:4n6 was recovered as prostaglandins PGE and PGF. The radioactivity from C18:2n6 that was recovered as PGE 1 and PGF 1α indicated elongation/desaturation to C20:3n6 followed by conversion to PG. 4. Since C18:2n6 is readily formed from acetate in T. commodus, these findings indicate the de novo biosynthesis of C20 polyunsaturated fatty acids and prostaglandins by this species.

Biosynthesis of polyunsaturated fatty acids by the australian field cricket, Teleogryllus commodus

Aspects of testicular fatty acid biochemistry from the Australian field cricket, Teleogryllus commodus, are reported. Over 10% of the phospholipid fatty acids were C20 polyunsaturated fatty acids (PUFAs), with nearly 6% arachidonic acid (20:4). The testes and ovaries accumulated a large proportion of label from radioactive arachidonic acid that was injected into the hemocoel (about 30%). Specificity in the uptake was shown by comparison to a similar study with labelled stearic acid, in which only 1.5% of the radioactivity was taken up by testes. Sixty percent of the radioactivity taken up by testes from [ 3H]20:4 was incorporated into phospholipids and 30% into triacylglycerols. Fat body of males and females incorporated 27% of the [ 3H]20:4 into phospholipids and 68% (males) or 55% (females) into triacylglcyerols. Radioactivity from [1- 14C]acetate was incorporated into testicular linoleic acid and eicosatrienoic acid, but not eicosatetraenoic acid, suggesting the de novo biosynthesis of both 18:2 and a C20 PUFA by this species. Label from injected [U- 14C]linoleic acid was recovered mostly as linoleic acid, with a small portion of the recovered radioactivity in eicosatrienoic acid, but not eicosatetraenoic acid. Very little label from injected linoleic acid occurred as monounsaturated or saturated fatty acids, indicating only slight, if any, β-oxidation of 18:2 to acetate and subsequent lipid synthesis.

Dendritic sprouting and compensatory synaptogenesis in an identified interneuron follow auditory deprivation in a cricket.

We examined the effect of chronic afferent deprivation on an identified interneuron (Int-1) in the auditory system of the Australian field cricket Teleogryllus oceanicus. In normal intact crickets, the auditory afferents from each ear terminate ipsilaterally onto a single Int-1. Each bilaterally paired Int-1 is excited by ultrasound stimulation of its ipsilateral ear but not by the contralateral ear. Unilateral removal of an ear early in postembryonic development deprives the developing Int-1 of ipsilateral auditory innervation. Consequently, the ipsilateral dendrites of the deprived interneuron sprout, grow aberrantly across the ganglionic midline, and terminate specifically in the intact auditory neuropile of the contralateral (unlesioned) side, where they form functional synapses with the contralateral afferents. This unusual compensatory dendritic sprouting restores auditory function to the neuron. Thus, it is demonstrated that the dendritic shape of an identified Int, as well as its synaptic connectivity, is altered as a consequence of chronic sensory deprivation.

The disappearance of injected prostaglandins from the circulation of adult female australian field crickets, Teleogryllus commodus

AbstractDuring the first 2 h following injection of 0.02 μCi of [14C]‐prostaglandin E2 into the abdomen of adult virgin female crickets, T. commodus, the concentration of radioactivity in the circulating hemolymph decreases. The reduction is associated with the increase in radioactivity in the Malpighian tubule/hindgut complex, ovaries, fat body, and, to a much smaller extent, ventral nerve cord and flight muscles. The finding that most, but not all, of the radioactivity in the hindgut is located in the contents of the lumen suggests that a high proportion of prostaglandins circulating in the hemolymph of T. commodus is eliminated by the usual excretory pathway. We suggest that the differential uptake of label from the circulating hemolymph by various tissues may be related to possible physiological functions that remain to be discovered.

Circadian control of singing in crickets: Two different pacemakers for early-evening and before-dawn activity

(1) Under LD 12:12 and constant temperature, calling song patterns of the Australian Field Cricket Teleogryllus commodus were frequently divided into two more or less distinct activity components. The first began 1–3 h before the L D -transition and ended with the sudden lights-off, whereas the second was restricted mainly to the second half of the night. In subsequent continuous light (LL) the circadian activity pattern was usually a unimodal band. Its onset slope was always a continuation of the first onsets in the preceding LD-cycle. In those cases where shortly after the LD LL transition the rhythm split into two components, both corresponded to those in LD. (2) In “atypical” LD-aatterns only the second component appeared during the late night. In such cases, the onset slope of the subsequent free-running rhythm did not start at the preceding LD-entrained onsets, but was advanced by several hours. (3) In free-running rhythms the mean value of the onset slopes ( τ o = 25.1 ± 0.07 h ) did not differ significantly from that of the end slopes ( τ e = 25.0 ± 0.07 h ). However, in individual activity patterns, simultaneous differences in onset and end slopes of up to 0.7 h were found. τ o- and τ e-values recorded directly after the LD LL -transition did not correlate with the preceding phase angle difference between the entrained activity and the zeitgeber. (4) Under constant conditions after-effects such as spontaneous period changes and phase shifts in the slopes of activity onset and/or end occurred mainly between five and 20 days after the LD LL -transition . (5) Period changes and phase delays in the onset and end slopes were also found when crickets were exposed to low temperature pulses (2 ± 2°C, 2h duration). Following the cold treatment both period changes and phase shifts in the onset slope frequently differed from those in the end slope. (6) The results are consistent with a concept of two activity components controlled by weakly coupled circadian pacemakers. This is clearly evident in split rhythms but is also true for unimodal patterns. Normally the two components partly overlap and their existence is concealed in the undivided activity band. They are only revealed in unimodal patterns if individual oscillatory properties such as different period lengths or phase shifts appear in the onset or the end slope.

A Study of the Behaviour of the Australian Field Cricket Teleogryllus commodus (Walker) (Orthoptera: Gryllidae) in the Field and in Habitat Simulations

Abstract and SummaryThe behaviour of T. commodus (Walker) in the field and in simulated natural habitats is described. Regular predictable sequences of behaviour are represented by an ethogram.Most behaviour was centred around burrows or sheltered sites. Burrows appeared to be a limiting resource and there may be behavioural dimorphism in ♂ ♂ (burrower and non‐burrower strategies).Individuals were found to form gregarious clusters and appeared to be attracted to areas already occupied by crickets. Territorial spacing and other social interactions occurred within these clusters.♂ ♂ and ♀ ♀ were found to be mobile, and moved continually between sites. The movement of ♂ ♂ and ♀ ♀ between burrows (calling sites) was measured. Adult ♂ ♂ never remained at a burrow for longer than two days. In simulated natural habitats ♂ ♂ moved in response to two factors: first, and most common, as a result of eviction by other ♂ ♂ second, as a response to the absence of ♀ ♀. When cricket density was increased in habitat simulations crickets clustered at calling sites.The adaptive significance of T. commodus behaviour is discussed.

Behavioral determination of frequency resolution in the ear of the cricket,Teleogryllus oceanicus

1. We used the flying phonotactic behavior of tethered female Australian field crickets,Teleogryllus oceanicus, to measure frequency filtering (determined from CR-bands, critical bands, and “effective” bandwidths) in the auditory system at frequencies of 4.5, 20, 40 and 70 kHz. Till now such measurements have been made only in vertebrates. 2. In CR-band determinations the spectrum level of the noise at the masked threshold increased monotonically with increasing tone level (Fig. 2). At 20, 40 and 70 kHz the regression lines had slopes very close to 1 indicating that, at least over the intensity range tested (5–20 dB above tone threshold), the masking process is linear. At 4.5 kHz, however, the slope of the regression line was only 0.56 showing a strong non-linearity in the masking process at this frequency. Such a nonlinearity has not been found in vertebrates. 3. At 4.5 kHz the three measures of filter bandwidths, CR-band, critical band and “effective” bandwidth, were not significantly different from each other, whereas at 40 kHz the “effective” bandwidth was significantly smaller than CR-band and critical band. 4. The width of the CR-band filter around 4.5 kHz increases with tone intensity, an effect which has not been observed in vertebrates. 5. Both CR-bands and critical bands indicate that the cricket auditory system is sharply tuned around 4.5 kHz, may show some tuning at 40 kHz, and is completely untuned at 20 and 70 kHz. 6. These results are discussed with respect to frequency tuning at the single unit level in crickets.

Serological Relations Between Twelve Small RNA Viruses of Insects

Serological tests were done to examine the relationships between twelve picorna-like viruses of insects. The results of the tests indicated that the majority of the viruses are unrelated. However, cricket paralysis virus, isolated from Australian wild field crickets, appeared to be identical to Drosophila C virus, independently isolated in France. Cricket paralysis virus was infective for adults of Drosophila melanogaster and its infectivity towards Galleria melonella was neutralised by Drosophila C virus antiserum. It is therefore concluded that cricket paralysis virus and Drosophila C virus are very closely related if not identical.

Frequency encoding in field crickets

We have studied the properties of auditory interneurons in field crickets as they relate to the encoding of frequency information in communication signals. Tungsten microelectrodes were used to record from single units in the neuropil of the prothoracic ganglion of the Australian field cricket, Teleogryllus oceanicus. Based on their maximal frequency sensitivity, four types of tonic, short-latency units were found: (1) 5-kHz units with ipsilateral input; (2) 5-kHz units with contralateral input; (3) broadly tuned 15-kHz units; and (4) 5-kHz units which are inhibited by frequencies below their best excitatory frequency. Thus information encoded in “labelled lines” was available at this level of the auditory system for both gross frequency discrimination between 5 and 15 kHz and fine frequency discrimination near 5kHz. The possibility also exists for latency encoding of frequencies near 5kHz due to the frequency-specific latency of the last type of interneuron listed.