Compensation of escape direction in unilaterally cercus-ablated crickets, Gryllus bimaculatus, is associated with the distance walked during recovery period

In response to an air puff stimulus, intact crickets, Gryllus bimaculatus, make an escape almost 180 degrees opposite to the stimulus source. In order to verify our previous hypothesis that a self-stimulation of the wind-sensory system is necessary for a compensational recovery of the escape direction (behavioral compensation) in unilaterally cercus-ablated crickets, we investigated the relationship between the conditions of rearing after a unilateral cercal ablation and the degree of behavioral compensation. A unilaterally cercus-ablated cricket reared in a large cage to permit free locomotion showed a significantly higher degree of recovery of escape direction compared with those reared under restrained conditions in a small glass vial. However, the degree of behavioral compensation in a cricket reared alone in a large cage was smaller than that of crickets reared in a cage of the same size with 5-6 other cercus-ablated crickets. Mutual stimulation possibly increased the extent of locomotion of crickets reared in a group and improved the degree of compensational recovery of the escape direction. To ascertain this, the distance a cricket moved during the recovery period was associated with the degree of compensational change of the escape direction. The result suggests that the degree of compensation of the escape direction clearly depended on the distance walked by the crickets. The compensation seemed not to be caused by other factors such as chemical ones in the case of group rearing because forced locomotion induced by touch stimulation on the body surface was solely effective in improving the escape direction.     

Rearing under different conditions results in different functional recoveries of giant interneurons in unilaterally cercus-ablated crickets, Gryllus bimaculatus

The effects of rearing conditions on the functional recovery of wind-sensitive giant interneurons (GIs) after unilateral cercal ablation were investigated in the cricket, Gryllus bimaculatus. Crickets were reared in a glass vials to prohibit free walking for 14 days after unilateral cercal ablation ("14-day vial" crickets). Other crickets were reared in an apparatus called a "walking inducer" (WI) to increase the walking distance during the same 14-day period ("14-day WI" crickets). In these crickets, the response properties of GIs 8-1, 9-1, 9-2, and 9-3 to air currents from various directions were investigated. From the intensity-response curves obtained, directionality curves expressed in terms of threshold velocity and response magnitude were made independently. To understand changes in the functional recovery of GIs more thoroughly, the directional characteristics of GIs in crickets 1 day after unilateral cercal ablation ("1-day free" crickets) were also compared. Between the 1-day free and 14-day vial crickets, all the GIs showed differences in both threshold velocity and response magnitude for some stimulus directions. Between the 14-day vial and 14-day WI crickets, differences in the threshold velocities of GIs 9-1, 9-2, and 9-3, and in the response magnitudes of GIs 8-1, 9-1, and 9-3 were detected. Because the rearing condition after unilateral cercal ablation largely affects the compensatory recovery in some parameters of wind-evoked escape behavior, such as relative occurrence and escape direction, we discuss the functional differences in GIs revealed here in relation to the roles of GIs in the neural system that controls escape behavior.     

Effects of self-generated wind on compensational recovery of escape direction in unilaterally cercus-ablated crickets, Gryllus bimaculatus

The effects of self-generated wind on the compensational recovery of escape direction were investigated in unilaterally cercus-ablated crickets, Gryllus bimaculatus. To separate walking and self-generated wind during walking, unilaterally cercus-ablated crickets were placed on a styrofoam ball that was easily rotated by leg motion during walking. The stationary walking on the ball did not produce self-generated wind, because no body motion occurred. Crickets that were trained on the ball but given no artificial air puff for 14 days after cercal ablation did not show any compensational recovery of escape direction. Therefore, spontaneous walking itself was not sufficient to compensate the wind-evoked escape direction in the crickets. Artificial air puffs from the anterior direction synchronized with the stationary walking were effective for the compensational recovery of escape direction, but those from the posterior direction were not. As most of the spontaneous walking was directed to the forward direction, only an artificial air puff from the anterior direction coincided well with actual self-generated wind occurring during the onset of normal walking. Therefore, self-generated wind during walking seems essential for the compensational recovery of escape direction in unilaterally cercus-ablated crickets. When artificial air puffs were unsynchronized with walking, no compensational recovery was observed. This result suggests that artificial air puffs should be given just after the onset of spontaneous walking. Otherwise, the artificial air puffs may not be recognized as self-generated wind.     

Behavioral analyses of wind-evoked escape of the cricket, Gryllodes sigillatus

The wind-evoked escape behavior of the cricket Gryllodes sigillatus was investigated using an air puff stimulus. A high velocity air puff elicited the escape behavior in many crickets. The crickets tended to escape away from the stimulus source, but the direction was not accurately oriented 180 degrees from the stimulus. After bilateral cercal ablation, only a few crickets showed wind-evoked escape behavior, and their response rates did not increase even 19 days after ablation. Therefore, information on air motion detected by cercal filiform hairs is essential for triggering wind-evoked behavior. After unilateral cercal ablation, the 81.3% response rate of intact crickets decreased to 16.5%, that is, it decreased to almost 20% that of intact crickets. One week after unilateral cercal ablation, the response rate recovered to more than 60% that of intact crickets. However, the accuracy rate of the escape direction of G. sigillatus showed no change even immediately after the unilateral cercal ablation. Therefore, both cerci are not necessarily required to determine the escape direction. The behavioral characteristics of wind-evoked escape of G. sigillatus are compared with those of another species of cricket, Gryllus bimaculatus. The two species of cricket employ different strategies for wind-evoked escape.     

Functional changes of cricket giant interneurons caused by chronic unilateral cercal ablation during postembryonic development

One of a pair of cerci was ablated in the first-, fourth- and last-instar nymphs of the cricket, Gryllus bimaculatus. The insects were then reared until the final molt, after which the intensity-response (I-R) relationships for four giant interneurons (GIs) 8-1, 9-1, 9-2 and 9-3 with regard to a controlled air current stimulus were measured. In order to examine the functional changes during postembryonic development and the differences in the physiological plasticity of GIs between nymphs and adults, the obtained I-R curves for each GI were compared with those measured in intact and unilaterally cercus-ablated adult crickets. Each GI showed a distinctive change in response magnitudes after the long-term unilateral cercal ablation. In most cases, the I-R curves for each GI in the crickets ablated from nymphal periods were different from those in the adult crickets mentioned above. Moreover, the pattern of change in response magnitude was different from GI to GI. In contrast to these observations, it was reported that some important characteristics of the wind-evoked escape behavior such as relative occurrence and escape direction in unilaterally cercus-ablated crickets investigated after a long-term rearing were almost identical with those in intact crickets. Therefore, the results obtained in the present study suggest that functional changes occur not only in GIs but also in many other neural elements in the escape-eliciting system in order to maintain the features of wind-evoked escape behavior.     

Sensitive period in which walking affects recovery of direction of wind-evoked escape in the cricket Gryllus bimaculatus

Unilaterally cercus-ablated crickets, Gryllus bimaculatus, were reared in an apparatus that induced walking artificially. In the crickets that experienced different distances of enforced walking per day, the directionality of escape was investigated before and 1, 4, 7, 10, 13, and 16 days after the ablation of the cercus. The crickets that walked a longer distance per day showed a quicker and a higher degree of compensational recovery of the escape direction than the crickets that walked a shorter distance per day, even after walking the same distance. Thus, the time course and amount of compensational recovery from cercal ablation depend on when crickets experience walking during the recovery period. During the recovery period, unilaterally cercus-ablated crickets were subjected to walking at different times to determine the most effective period in which walking affects the compensational recovery of escape direction. The compensational recovery of the escape direction occurred only in crickets experiencing walking in early periods after the ablation. In particular, walking experienced 2-6 days after the ablation was most effective for the compensational recovery. On the other hand, no compensational recovery occurred in crickets experiencing walking in later periods after the ablation. These results suggest that there is a sensitive or critical period in which walking affects the compensational recovery of escape direction.     

The fight and flight responses of crickets depleted of biogenic amines

Aggressive and escape behaviors were analysed in crickets (Orthoptera) treated with either reserpine, a nonspecific depleter of biogenic amines, or the synthesis inhibitors alpha-methyltryptophan (AMTP) and alpha-methyl-p-tyrosine (AMT) to specifically deplete serotonin, respectively dopamine and octopamine. Standard immunocytochemical techniques were used to verify depletion from central nervous tissue, and determine the effective dosages. Reserpinized crickets became exceedingly lethargic and had severely depressed escape responses. However, they were still able to express all the major elements of the escalating sequences of stereotype motor performances that typifies normal aggressive behavior in the cricket. AMT and AMTP treatment had opposing influences on escape behavior, being enhanced by serotonin depletion, but depressed by dopamine/octopamine depletion. AMTP-induced serotonin depletion had no influence on aggressive or submissive behaviors. AMT-treated crickets could normally only be brought to fight by coaxing. Though capable of expressing aggressive behavior per se, agonistic encounters between AMT-treated crickets were shorter, and rarely involved actual physical interactions. Hence, although amines seem to have similar actions on escape behavior in insects and crustaceans, the aminergic control of aggression seems to be fundamentally different in these arthropods groups. We conclude that amines are not in principle required for the initiation and operation of the motor circuits underlying aggression in the cricket. However, octopamine and/or dopamine seem necessary for establishing a level of excitability sufficient for aggressive behavior to become overt in response to appropriate natural releasing stimuli.     

Understanding the regulation and function of adult neurogenesis: contribution from an insect model, the house cricket

Since the discovery of adult neurogenesis, a major issue is the role of newborn neurons and the function-dependent regulation of adult neurogenesis. We decided to use an animal model with a relatively simple brain to address these questions. In the adult cricket brain as in mammals, new neurons are produced throughout life. This neurogenesis occurs in the main integrative centers of the insect brain, the mushroom bodies (MBs), where the neuroblasts responsible for their formation persist after the imaginal molt. The rate of production of new neurons is controlled not only by internal cues such as morphogenetic hormones but also by external environmental cues. Adult crickets reared in an enriched sensory environment experienced an increase in neuroblast proliferation as compared with crickets reared in an impoverished environment. In addition, unilateral sensory deprivation led to reduced neurogenesis in the MB ipsilateral to the lesion. In search of a functional role for the new cells, we specifically ablated MB neuroblasts in young adults using brain-focused gamma ray irradiation. We developed a learning paradigm adapted to the cricket, which we call the "escape paradigm." Using this operant associative learning test, we showed that crickets lacking neurogenesis exhibited delayed learning and reduced memory retention of the task when olfactory cues were used. Our results suggest that environmental cues are able to influence adult neurogenesis and that, in turn, newly generated neurons participate in olfactory integration, optimizing learning abilities of the animal, and thus its adaptation to its environment. Nevertheless, odor learning in adult insects cannot always be attributed to newly born neurons because neurogenesis is completed earlier in development in many insect species. In addition, many of the irradiated crickets performed significantly better than chance on the operant learning task.     

Limited flexibility in female Pacific field cricket (Teleogryllus oceanicus) exploratory behaviors in response to perceived social environment

How populations adapt, or not, to rapid evolution of sexual signals has important implications for population viability, but is difficult to assess due to the paucity of examples of sexual signals evolving in real time. In Hawaiian populations of the Pacific field cricket (Teleogryllus oceanicus), selection from a deadly parasitoid fly has driven the rapid loss of a male acoustic signal, calling song, that females use to locate and evaluate potential mates. In this newly quiet environment where many males are obligately silent, how do phonotactic females find mates? Previous work has shown that the acoustic rearing environment (presence or absence of male calling song) during late juvenile stages and early adulthood exposes adaptive flexibility in locomotor behaviors of males, as well as mating behaviors in both sexes that helps facilitate the spread of silent (flatwing) males. Here, we tested whether females also show acoustically induced plasticity in walking behaviors using laboratory‐reared populations of T. oceanicus from Kauai (HI; >90% flatwings), Oahu (HI; ~50% flatwings), and Mangaia (Cook Islands; no flatwings or parasitoid fly). Though we predicted that females reared without song exposure would increase walking behaviors to facilitate mate localization when song is rare, we discovered that, unlike males, female T. oceanicus showed relatively little plasticity in exploratory behaviors in response to an acoustic rearing environment. Across all three populations, exposure to male calling song during development did not affect latency to begin walking, distance walked, or general activity of female crickets. However, females reared in the absence of song walked slower and showed a marginally non‐significant tendency to walk for longer durations of time in a novel environment than those reared in the presence of song. Overall, plasticity in female walking behaviors appears unlikely to have facilitated sexual signal loss in this species.     

Species-Recognition in the Field Cricket, Teleogryllus oceanicus: Behavioral and Neural Mechanisms

SYNOPSIS. Field crickets depend on acoustic organs to detectthe presence of potential predators as well as conspecific crickets.Predators are recognized largely on the basis of spectral frequenciesthat are contained in their acoustic signals. Puffs of air andvery low frequencies activate a cricket's cereal receptors andultrasonic frequencies activate their tympanal organs. Bothof these acoustic stimuli release "escape behavior," in theform of evasive movements. An identified neuron sensitive toultrasound is described. Crickets recognize singing conspecificsby both frequency and temporal properties of cricket songs;however species recognition requires specific temporal informationin calling songs. While previous studies have emphasized therole of songs on female behavior, males also recognize conspecificsongs; sexual differences in recognition behavior occur.     

Reproductive Compensation: A Review of the <Emphasis Type="Italic">Gryllus</Emphasis> spp.—<Emphasis Type="Italic">Ormia ochracea</Emphasis> Host-Parasitoid System

Calling male field crickets (Gryllus spp.) are acoustically located and subsequently parasitized by the parasitoid fly, Ormia ochracea (Diptera: Tachinidae). Parasitism by O. ochracea results in cricket death. The reproductive compensation hypothesis posits that when a host’s residual reproductive value decreases, it would be adaptive for that host to shift its resources into current reproduction. Reproductive compensation has not been observed in the cricket-fly system. Here we review the studies to date that have investigated reproductive compensation in the cricket-fly interaction, in an attempt to understand why crickets do not compensate for their future reproductive losses. We conclude that the cricket-fly interaction may not be an ideal system in which to investigate reproductive compensation and furthermore, that reproductive compensation has been poorly investigated in this system.     

Prothoracic DUM neurons of the cricket Gryllus bimaculatus — responses to natural stimuli and activity in walking behavior

Summary Responses to sensory stimuli and spike activity uring walking were investigated in bilaterally symmetrical dorsal unpaired median (DUM) neurons of the cricket. Intracellular recordings within the prothoracic ganglion were made either in restrained animals or in stationary walking specimens whilst parameters of their intended locomotion were measured. Three types of DUM cells were distinguished morphologically and physiologically. DUMa neurons send axons through segmental nerves. They often generated spontaneously large action potentials with low frequencies. Most DUMa neurons showed multimodal sensitivity, preferentially to cereal wind puffs and 15 kHz sound. Mean latencies ranged from 25 to 349 ms. Their large intraindividual variability could be correlated with behavioral modes during walking. Generally, the spike frequency increased with increased forward speed, while it was not related to turning. DUMb neurons projected either through the anterior or posterior connectives, but seemed physiologically similar to DUMa neurons. DUMc neurons were H-shaped with axons in both pairs of connectives. No external stimulus led to discrete spikes, but the regular spontaneous activity was modulated following cereal wind puffs to a restrained animal. During wind evoked escape the spike activity of another DUMc cell was modulated in phase with the rhythmic running behavior. The possibly different functions of DUMa and DUMc neurons during walking are discussed.     

The precision of auditory lateralization in the cricket, Gryllus bimaculatus

ABSTRACT. The precision of auditory lateralization was determined behaviourally for the cricket, Gryllus bimaculatus L. A forced-choice Y-maze test was devised in which the cricket, on entering the test arena, could not — in contrast to free phonotactic approaches — change its walking direction until after it had passed through a narrow wire-mesh tunnel. For a sound frequency of 4.7 kHz, matching the species' calling frequency, the minimum audible angle for correct side discrimination was 15°. For stimulus angles smaller than 15° from the longitudinal body axis, the crickets walked randomly to either side; stimulus angles greater than 25° resulted in all crickets turning correctly. These data reveal a sharply tuned lateral sensitivity for the auditory pathway of crickets, with an optimum at the species' calling frequency of 4.7 kHz (when compared with 3.5 and 6.0 kHz). The results for the forced-choice test are compared with the walking pattern during free phonotactic approaches, in order to determine the possible strategy underlying the acoustic orientation behaviour of the cricket.     

The aerodynamic signature of running spiders

Many predators display two foraging modes, an ambush strategy and a cruising mode. These foraging strategies have been classically studied in energetic, biomechanical and ecological terms, without considering the role of signals produced by predators and perceived by prey. Wolf spiders are a typical example; they hunt in leaf litter either using an ambush strategy or by moving at high speed, taking over unwary prey. Air flow upstream of running spiders is a source of information for escaping prey, such as crickets and cockroaches. However, air displacement by running arthropods has not been previously examined. Here we show, using digital particle image velocimetry, that running spiders are highly conspicuous aerodynamically, due to substantial air displacement detectable up to several centimetres in front of them. This study explains the bimodal distribution of spider's foraging modes in terms of sensory ecology and is consistent with the escape distances and speeds of cricket prey. These findings may be relevant to the large and diverse array of arthropod prey-predator interactions in leaf litter.     

Hair canopy of cricket sensory system tuned to predator signals

Filiform hairs located on the cerci of crickets are among the most sensitive sensors in the animal world and enable crickets to sense the faintest air movements generated by approaching predators. While the neurophysiological and biomechanical aspects of this sensory system have been studied independently for several decades, their integration into a coherent framework was wanting. In order to evaluate the hair canopy tuning to predator signals, we built a model of cercal population coding of oscillating air flows by the hundreds of hairs on the cerci of the sand cricket Gryllus bimaculatus (Insecta: Orthoptera). A complete survey of all hairs covering the cerci was done on intact cerci using scanning electronic microscopy. An additive population coding of sinusoid signals of varying frequencies and velocities taking into account hair directionality delivered the cercal canopy tuning curve. We show that the range of frequencies and velocities at which the cricket sensory system is best tuned corresponds to the values of signals produced by approaching predators. The relative frequencies of short (< 0.5 x 10(-3) m) and long hairs and their differing responses to oscillating air flows therefore enable crickets to detect predators in a time-frequency-intensity space both as far as possible and at close range.     

Danger detection and escape behaviour in wood crickets

The wind-sensitive cercal system of Orthopteroid insects that mediates the detection of the approach of a predator is a very sensitive sensory system. It has been intensively analysed from a behavioural and neurobiological point of view, and constitutes a classical model system in neuroethology. The escape behaviour is triggered in orthopteroids by the detection of air-currents produced by approaching objects, allowing these insects to keep away from potential dangers. Nevertheless, escape behaviour has not been studied in terms of success. Moreover, an attacking predator is more than “air movement”, it is also a visible moving entity. The sensory basis of predator detection is thus probably more complex than the perception of air movement by the cerci. We have used a piston mimicking an attacking running predator for a quantitative evaluation of the escape behaviour of wood crickets Nemobius sylvestris. The movement of the piston not only generates air movement, but it can be seen by the insect and can touch it as a natural predator. This procedure allowed us to study the escape behaviour in terms of detection and also in terms of success. Our results showed that 5-52% of crickets that detected the piston thrust were indeed touched. Crickets escaped to stimulation from behind better than to a stimulation from the front, even though they detected the approaching object similarly in both cases. After cerci ablation, 48% crickets were still able to detect a piston approaching from behind (compared with 79% of detection in intact insects) and 24% crickets escaped successfully (compared with 62% in the case of intact insects). So, cerci play a major role in the detection of an approaching object but other mechanoreceptors or sensory modalities are implicated in this detection. It is not possible to assure that other sensory modalities participate (in the case of intact animals) in the behaviour; rather, than in the absence of cerci other sensory modalities can partially mediate the behaviour. Nevertheless, neither antennae nor eyes seem to be used for detecting approaching objects, as their inactivation did not reduce their detection and escape abilities in the presence of cerci.     

Basic elements of behavior of the cricket <Emphasis Type="Italic">Phaeophilacris bredoides</Emphasis> Kaltenbach (Orthoptera,Gryllidae)

The intraspecific behavior of the non-singing cricket Phaeophilacris bredoides Kaltenbach, 1986, which has no tympanal system, stridulatory apparatus, and classical acoustic communication, was studied. Even though this cricket has no song, its intraspecific behavior can be differentiated into reproductive and agonistic (defensive and aggressive), as this was done before for singing crickets. The main elements and the sequence of the phases were described for reproductive behavior. The active role during copulation belongs to the male. Wingflicks and rocking movements of the male can function as a “song.” Wing-flicks apparently generate air movements that function as short-range signals during reproductive and aggressive behavior. Substrate-borne vibrations produced by rocking also seem to be associated with aggressive behavior. Antennal contacts form an important part of interaction between crickets of both sexes. Thus, intraspecific signaling is at least partly mediated by mechanosensory channels. The assumption about the possible direction of evolution in the singing and non-singing groups of crickets was made.     

Entomopathogenic fungi detection and avoidance by mole crickets (Orthoptera: Gryllotalpidae)

A chamber to monitor mole cricket behavior was designed using two different soil-filled containers and photosensors constructed from infrared emitters and detectors. Mole crickets (Scapteriscus spp.) were introduced into a center tube that allowed them to choose whether to enter and tunnel in untreated soil or soil treated with Beauveria bassiana (Balsamo) Vuillemin. Each time the cricket passed through the photosensor located near the entrance of soil-filled containers, the infrared light was blocked and the exact moment that this occurred was logged onto a computer using custom-written software. Data examined included the first photosensor trigger, total number of sensor triggers, presence of tunneling, and final location of the cricket after 18 h. These behaviors were analyzed to discern differences in mole cricket behavior in the presence of different treatments and to elucidate the mechanism that mole crickets use to detect fungal pathogens. The first study examined substrate selection and tunneling behavior of the southern mole cricket, Scapteriscus borellii Giglio-Tos, to the presence of five strains of B. bassiana relative to a control. There were no differences between the first sensor trigger and total number of triggers, indicating the mole crickets are not capable of detecting B. bassiana at a distance of 8 cm. Changes in mole cricket tunneling and residence time in treated soil occurred for some strains of B. bassiana but not others. One of the strains associated with behavioral changes in the southern mole cricket was used in a second experiment testing behavioral responses of the tawny mole cricket, S. vicinus Scudder. In addition to the formulated product of this strain, the two separate components of that product (conidia and carrier) and bifenthrin, an insecticide commonly used to control mole crickets, were tested. There were no differences in mole cricket behavior between treatments in this study. The differences in behavioral responses between the two species could suggest a more sensitive chemosensory recognition system for southern mole crickets.     

Does Rearing Laying Hens in Aviaries Adversely Affect Long-Term Welfare following Transfer to Furnished Cages?

This study tests the hypothesis that hens that are reared in aviaries but produce in furnished cages experience poorer welfare in production than hens reared in caged systems. This hypothesis is based on the suggestion that the spatial restriction associated with the transfer from aviaries to cages results in frustration or stress for the aviary reared birds. To assess the difference in welfare between aviary and cage reared hens in production, non-beak trimmed white leghorn birds from both rearing backgrounds were filmed at a commercial farm that used furnished cage housing. The videos were taken at 19 and 21 weeks of age, following the birds'' transition to the production environment at 16 weeks. Videos were analysed in terms of the performance of aversion-related behaviour in undisturbed birds, comfort behaviour in undisturbed birds, and alert behaviour directed to a novel object in the home cage. A decrease in the performance of the former behaviour and increase in the performance of the latter two behaviours indicates improved welfare. The results showed that aviary reared birds performed more alert behaviour near to the object than did cage reared birds at 19 but not at 21 weeks of age (P = 0.03). Blood glucose concentrations did not differ between the treatments (P>0.10). There was a significant difference in mortality between treatments (P = 0.000), with more death in aviary reared birds (5.52%) compared to cage birds (2.48%). The higher mortality of aviary-reared birds indicates a negative effect of aviary rearing on bird welfare, whereas the higher duration of alert behavior suggests a positive effect of aviary rearing.     

Analysis of behavioral selection after sensory deprivation of legs in the cricket Gryllus bimaculatus

An air puff stimulus evoked the swimming of an intact cricket, Gryllus bimaculatus, placed on a water surface. When only the forelegs were intact, swimming was initiated frequently, but flying was never initiated. On the other hand, flying was initiated when only the middle legs or hindlegs were intact. Therefore, the sensory inputs from the forelegs are important in the initiation of swimming and for the inhibition of flying when on the water surface. After bilateral ablation of the middle legs and hindlegs, the bilateral segments of the remaining forelegs were sequentially ablated from the distal area to the proximal area of the legs. After bilateral ablation of all tarsomeres, the relative occurrence of swimming decreased and that of flying increased. After the following ablation of the bilateral tibiae, most insects responded to an air puff stimulus by flying. Experiments performed after coating the leg surface with enamel resulted in almost the same behavioral change as that observed in the ablation experiments. These results suggest that the sensory receptors responsible for the initiation of swimming and the inhibition of flying are mainly located on the surface of the tibia and the tarsus of the forelegs. The behavioral change between swimming and walking was also studied using methylcellulose solutions of various viscosities. On the methylcellulose solution, the relative occurrence of walking in the crickets increased with an increase in the viscosity of the solution.