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The role of edges in the selection of a jump target in Mantis religiosa.

Before jumping to a landing object, praying mantids determine the distance, using information obtained from retinal image motion resulting from horizontal peering movements. The present study investigates the peering-jump behaviour of Mantis religiosa larvae with regard to jump targets differing in shape and size. The experimental animals were presented with square, triangular and round target objects with visual extensions of 20 degrees and 40 degrees. The cardboard objects, presented against a uniform white background, were solid black or shaded with a gradation from white to black. It was found that larger objects were preferred to smaller ones as jump targets, and that the square and triangle were preferred to the round disk. When two objects were presented, no preference was exhibited between square and triangular objects. However, when three objects were presented, the square was preferred. For targets with a visual angle of 40 degrees, the amplitude and velocity of the horizontal peering movements were greater for the round disk than for the square or triangle. This amplification of the peering movements suggests that weaker motion signals are generated in the case of curved edges. This may help to account for the preference for the square and triangle as jump targets.

Animals↗

Investigating saccade programming in the praying mantis Tenodera aridifolia using distracter interference paradigms.

To investigate the saccadic system in the mantis, I applied distracter interference paradigms. These involved presenting the mantis with a fixation target and one or several distracters supposed to affect saccades towards the target. When a single target was presented, a medium-sized target located in its lower visual field elicited higher rates of saccade response. This preference for target size and position was also observed when a target and a distracter were presented simultaneously. That is, the mantis chose and fixated the target rather than a distracter that was much smaller or larger than the target, or was located above the target. Furthermore, the mantis' preference was not affected by increasing the number of distracters. However, the presence of the distracter decreased the occurrence rate of saccade and increased the response time to saccade. I conclude that distracter interference paradigms are an effective way of investigating the visual processing underlying saccade generation in the mantis. Possible mechanisms of saccade generation in the mantis are discussed.

Animals↗

Serotonin-immunoreactive neurones in the visual system of the praying mantis: an immunohistochemical, confocal laser scanning and electron microscopic study.

The distribution, number, and morphology of serotonin-immunoreactive (5-HTi) neurones in the optic lobe of the praying mantis Tenodera sinensis were studied using conventional microscopy and confocal laser scanning microscopy. Five or six 5-HTi neurones connect the lobula complex with the medulla, and at least 50 5-HTi neurones appear to be confined to the medulla. In addition, a few large 5-HTi processes from the protocerebrum supply the lobula complex, and two large 5-HTi processes from the protocerebrum ramify in the medulla and lamina, where they show wide field arborisations. In order to provide a basis for understanding the action of serotonin in the lamina, the ultrastructure of its 5-HTi terminals was examined by conventional and immunohistochemical electron microscopy. The 5-HTi profiles were filled with dense core vesicles and made synapses. Output synapses from 5-HTi profiles outnumbered inputs by about 3 to 1. The terminals of the 5-HTi neurones were in close contact with cells of various types, including large monopolar cells, but close apposition to photoreceptor terminals was rare, and no synapses were found between 5-HTi terminals and photoreceptor terminals.

Anatomy, Artistic↗

Purification and characterization of a serine protease with fibrinolytic activity from Tenodera sinensis (praying mantis).

Mantis egg fibrolase (MEF) was purified from the egg cases of Tenodera sinensis using ammonium sulfate fractionation, gel filtration on Bio-Gel P-60 and affinity chromatography on DEAE Affi-Gel blue gel. The protease was assessed homogeneous by SDS-polyacrylamide gel electrophoresis and has a molecular mass of 31500 Da. An isoelectric point of 6.1 was determined by isoelectric focusing. Amino acid sequencing of the N-terminal region established a primary structure composed of Ala-Asp-Val-Val-Gln-Gly-Asp-Ala-Pro-Ser. MEF readily digested the Aalpha- and Bbeta-chains of fibrinogen and more slowly the gamma-chain. The nonspecific action of the enzyme results in extensive hydrolysis of fibrinogen and fibrin releasing a variety of fibrinopeptide. The enzyme is inactivated by Cu2+ and Zn2+ and inhibited by PMSF and chymostatin, yet elastinal, aprotinin, TLCK, TPCK, EDTA, EGTA, cysteine, beta-mercaptoethanol, iodoacetate, E64, benzamidine and soybean trypsin inhibitor do not affect activity. Antiplasmin was not sensitive to MEF but antithrombin III inhibited the enzymatic activity of MEF. Among chromogenic protease substrates, the most sensitive to MEF hydrolysis was benzoyl-Phe-Val-Arg-p-nitroanilide with maximal activity at pH 7.0 and 30 degrees C. MEF preferentially cleaved the oxidized B-chain of insulin between Leu15 and Tyr16. D-Dimer concentrations increased on incubation of cross-linked fibrin with MEF, indicating the enzyme has a strong fibrinolytic activity.

Amino Acid Sequence↗

Purification and characterization of a plasmin-like protease from Tenodera sinensis (Chinese mantis).

A novel type of protease (mantis egg fibrinolytic enzyme, MEF-2) was isolated from the egg cases of Tenodera sinensis. The protease was homogeneous by SDS-PAGE and its apparent molecular mass was 32,900 Da. The amino acids in the N-terminal region were Ile-Val-Gly-Gly-Glu-Glu-Ala-Val-Ala-Gly-Asp-Phe-Pro-Ile-Val-Ser-Leu-Gln-Glu. The enzyme was inhibited by PMSF, TLCK, aprotinin, benzamidine, soybean trypsin inhibitor and also slightly by elastatinal, EDTA, EGTA, cysteine and beta-mercaptoethanol, but TPCK, iodoacetate and E-64 did not affect the activity. MEF-2 was not sensitive to alpha(1)-antitrypsin but antithrombin III and alpha(2)-antiplasmin inhibited the enzyme. MEF-2 preferentially cleaved the oxidized B-chain of insulin between Arg(22) and Gly(23). Among chromogenic protease substrates, the most susceptible to MEF-2 hydrolysis was benzoyl-Phe-Val-Arg-p-nitroanilide with maximal activity at 30 degrees C and pH 5.0. These results indicate that MEF-2 belongs to the trypsin family. Upon incubation of crosslinked fibrin with MEF-2, a steady increase of D-dimer suggests that the enzyme has a strong fibrinolytic activity. In conclusion, MEF-2 is a new type of proteolytic enzyme and has some potential for practical application in fibrinolysis.

Amino Acid Sequence↗

Gold toning preserves integrity of silver enhanced immunogold particles during osmium tetroxide treatment for demonstration of a biogenic amine.

We describe a protocol that enhances immunolabelling of nervous tissue for ultrastructural study. Insect tissue is fixed, sectioned, and labelled with a polyclonal antiserum against serotonin and a secondary antibody conjugated with 1 nm colloidal gold. The gold particles are silver-enhanced to ease detection and then protected by gold toning. Finally, the tissue is post fixed in glutaraldehyde fixative followed by osmium tetroxide and further processed for electron microscopy. We demonstrated on insect nervous tissue that gold toning protects marker particles from the influence of osmium tetroxide. Use of buffered solutions throughout the protocol led to well preserved ultrastructural details, and marker particle size was not reduced with a short gold toning time. We also suggest use of this protocol for vertebrate or other invertebrate tissue.

Animals↗

Complicity or conflict over sexual cannibalism? Male risk taking in the praying mantis Tenodera aridifolia sinensis.

Male complicity versus conflict over sexual cannibalism in mantids remains extremely controversial, yet few studies have attempted to establish a causal relationship between risk of cannibalism and male reproductive behavior. We studied male risk-taking behavior in the praying mantid Tenodera aridifolia sinensis by altering the risk imposed by females and measuring changes in male behavior. We show that males were less likely to approach hungrier, more rapacious females, and when they did approach, they moved more slowly, courted with greater intensity, and mounted from a greater distance. Similarly, when forced to approach females head-on, within better view and better reach of females, males also approached more slowly and courted with greater intensity. Thus, males behaved in a manner clearly indicative of risk avoidance, and we support the hypothesis of sexual conflict over sexual cannibalism.

Animals↗

Responses of movement-sensitive visual interneurons to prey-like stimuli in the praying mantis Sphodromantis lineola (Burmeister).

Previous behavioral work using both mechanical and computer-generated visual stimuli has demonstrated that mantids use a computational algorithm to recognize prey similar to that used by some amphibian predators: A stimulus elicits prey capture behavior if it falls within a perceptual envelope defined by five fundamental stimulus parameters: (1) overall size, (2) length of the leading edge, (3) contrast to the background, (4) location in the visual field, and (5) apparent speed. In this study, we recorded simultaneously from both cervical nerve cords of monocular Sphodromantis lineola while they viewed the same visual stimuli successfully used in the behavioral studies. Extracellular recordings showed three consistently proportioned amplitude classes of movement-elicited spikes in each cord and these were repeatedly and reliably identifiable across mantids. Overall, the movement-elicited activity in both cords was dominated by very large spikes suggesting the existence of several large, descending movement-sensitive interneurons projecting both ipsilaterally and contralaterally from the optic lobes. However, only the largest contralateral spikes occurred preferentially to prey-like stimuli, mirrored the behavioral response curves generated by S. lineola to the same visual stimuli, and displayed activity peaks that were correlated with the times at which the mantid emitted predatory strikes.

Animals↗

Timing of praying mantis evasive responses during simulated bat attack sequences.

Praying mantids perform evasive maneuvers that vary with the level of danger posed by their bat predators. The vocalization pattern of attacking bats provides cues that mantids can potentially use to decide how and when to respond. Using pulse trains simulating bat attack echolocation sequences, this study determines when in the attack sequence the mantis power dive (its response to high-level threat) occurs and predicts the parameters within the echolocation sequence that are important for eliciting the response. For sequences with a rapid transition from low to high pulse repetition rates (PRRs), the evasive response occurred close to the point during the simulated sequence when the bat would have contacted the mantis. However, the evasive response occurred earlier if the transition was gradual. Regardless of the transition type, the prediction data show that sequences trigger the response when PRRs reach 20-40 pulses s(-1). These results suggest that a bat gradually increasing its PRR could 'tip off' the mantis, enabling it to escape. Attack sequences contain gradual transitions when bats engage in strobing behavior, an echolocation phenomenon that may help the bat perceive the auditory scene. Conversely, bat attack sequences that contain rapid increases in PRR close to the point of capture could circumvent the mantid's auditory defense. Based on these findings, mantids as well as other insects could benefit from having a back-up defense response to offset any advantage the bat gains by rapidly switching from low to high PRRs.

Acoustic Stimulation↗

Wind generated by an attacking bat: anemometric measurements and detection by the praying mantis cercal system.

The wind-sensitive cercal system, well-known for mediating terrestrial escape responses, may also mediate insect aerial bat-avoidance responses triggered by wind generated by the approaching bat. One crucial question is whether enough time exists between detection and capture for the insect to perform a successful evasive maneuver. A previous study estimated this time to be 16 ms, based on cockroach behavioral latencies and a prediction for the detection time derived from a simulated predator moving toward a simulated prey. However, the detection time may be underestimated since both the simulated predator and prey lacked certain characteristics present in the natural situation. In the present study, actual detection times are measured by recording from wind-sensitive interneurons of a tethered praying mantis that serves as the target for a flying, attacking bat. Furthermore, using hot-wire anemometry, we describe and quantify the wind generated by an attacking bat. Anemometer measurements revealed that the velocity of the bat-generated wind consistently peaks early with a high acceleration component (an important parameter for triggering wind-mediated terrestrial responses). The physiological recordings determined that the mantis cercal system detected an approaching bat 74 ms before contact, which would provide the insect with 36 ms to perform a maneuver before capture. This should be sufficient time for the mantis to respond. Although it probably would not have time for a full response that completely evades the bat, even a partial response might alter the mantid's trajectory enough to cause the bat to mishandle the insect, allowing it to escape.

Air Movements↗

Implanted electrode recordings from a praying mantis auditory interneuron during flying bat attacks.

Using an implanted electrode, we recorded the responses from the ultrasound-sensitive mantis interneuron 501-T3 during flying bat attacks in a large flight room where the mantis served as the target. 501-T3 responds to each vocalization emitted with multi-spike bursts when pulse repetition rates (PRRs) are below 55 pulses x s(-1). As PRR increases and pulse durations fall below 3 ms, 501-T3 ceases burst activity. On average, spike bursts cease 272 ms before contact (when the bat is 73 cm away from the preparation). The timing of cessation of activity in 501-T3 is similar to the latency for the diving portion of the response of the mantid (242 ms). Experiments using vocalizing stationary bats confirm that 501-T3 responds more reliably to longer pulse durations (> or =3 ms) when intensities are below 90 dB pe SPL. The cessation of 501-T3 activity is probably due both to the increasing PRR and to the decreasing pulse duration that occur in the terminal buzz phase of a bat attack. 501-T3 may be actively shut off at high PRRs and/or intensities to protect the interneuron from habituation while the mantis performs an escape response. The cessation of 501-T3 activity is consistent with the lack of a very late ultrasound-mediated evasive response by the mantis. However, cessation of 501-T3 activity may allow a true 'last-chance' response to be mediated by other neural systems.

Animals↗

Two new species of nematodes (Rhabditida: Diplogasteridae and Rhabditidae) parasites of Gryllodes laplatae (Orthoptera: Gryllidae) in Argentina.

Cephalobium magdalensis n. sp. (Rhabditida: Diplogasteridae) found in Magdalena, Buenos Aires, and Cruznema lincolnensis n. sp. (Rhabditida: Rhabditidae) found in Lincoln, Buenos Aires, parasitizing the cricket Gryllodes laplatae (Orthoptera: Gryllidae) are described and illustrated. C. magdalensis n. sp. is characterized by having the excretory pore between the pseudobulb and the basal bulb and seven pairs of postanal papillae in the male. C. lincolnensis n. sp. can be distiguished by having meanly two pairs of preanal papillae, one pair of adanal papillae and six pairs of postanal papillae in the male.

Animals↗

Response properties of visual interneurons to motion stimuli in the praying mantis, Tenodera aridifolia.

Intracellular responses of motion-sensitive visual interneurons were recorded from the lobula complex of the mantis, Tenodera aridifolia. The interneurons were divided into four classes according to the response polarity, spatial tuning, and directional selectivity. Neurons of the first class had small, medium, or large receptive fields and showed a strong excitation in response to a small-field motion such as a small square moving in any direction (SF neurons). The second class neurons showed non-directionally selective responses: an excitation to a large-field motion of gratings in any direction (ND neurons). Most ND neurons had small or medium-size receptive fields. Neurons of the third class had large receptive fields and exhibited directionally selective responses: an excitation to a large-field motion of gratings in preferred direction and an inhibition to a motion in opposite, null direction (DS neurons). The last class neurons had small receptive fields and showed inhibitory responses to a moving square and gratings (I neurons). The functional roles of these neurons in prey recognition and optomotor response were discussed.

Animals↗

Thoracic and prothoracic leg neuromuscular system of the praying mantid, Sphodromantis lineola (Burmeister).

Historically, praying mantids have attracted attention because of their dramatic prey capture behavior, loosely termed the strike. However, little is known about the neuromuscular organization that underpins the behavior. Although once thought to be quite stereotyped, recent data indicate that the strike is quite plastic and can be aimed accurately within a relatively large three-dimensional space. Hence, successful prey capture requires the integration of (1) visual information, indicating prey has been recognized; and (2) proprioceptive information, indicating head and prothorax (i.e., visual field) position and initial leg positions. This study was undertaken as part of a larger program examining how such sensory information is integrated with the appropriate motor systems. Our goals were (1) to describe the gross thoracic and foreleg neuromuscular system of Sphodromantis lineola and (2) to identify the soma locations of the motor neurons associated with the largest leg nerve, N4, which travels the length of each leg. We found that the thoracic and foreleg neuromusculature of S. lineola are similar but not identical to what is known about just three other species of mantid, and that motor neuron somata associated with N4 are arranged in stereotypical, bilaterally symmetrical groups as they are in other orthopteroids, suggesting that this is a general organizational feature of the insect CNS.

Animals↗