Effects of ambient temperature,humidity, and age on wing-beat frequency of Periplaneta species

Wing-beat frequency of 2-week-old male Periplaneta americana cockroaches was measured during tethered flight at ambient temperatures from 19 to 35°C and 50 and 95% r.h. Between 19 and 27°C the frequency increased at a nearly constant rate (0·6 Hz/deg at 50% r.h.; 0·7 Hz/deg at 95% r.h.), but the rate of increase decreased markedly between 27 and 35°C. This decline differed from results of past investigations of wing-beat frequency for this species. Wing-beat frequencies at 95% r.h. were significantly higher than those at 50% r.h. for ambient temperatures between 27 and 35°C. reductions in wing-beat frequency at high temperatures and differences in wing-beat frequency between 50 and 95% r.h. may reflect decreases in internal thoracic temperature resulting from cuticular water loss.     

Time-correlated flights of juvenile and mature locusts: A comparison between free and tethered animals

The flights of free and tethered Locusta migratoria were followed from initiation with a high-speed film camera. A longer sequence of wing-beat cycles can thus be correlated unequivocally with the animals's movement in time and space. In both flight situations the locusts start with approximately the same instantaneous wing-beat frequency. During the early flight phase free-flying animals increase their wing-beat frequency, whereas for tethered locusts this parameter remains constant or even decreases. The general flight pattern is similar in juvenile and mature locusts; the juveniles however, fly with alower wing-beat frequency and flight speed. The differences in the wing-beat frequencies for both flight performances are discussed with respect to differences in the sensory inputs to the flight motor centre.     

Mitochondria in the flight muscles of insects. III. Mitochondrial cytochrome c in relation to the aging and wing beat frequency of flies

1. In the present study a correlation has been sought between aging, flight muscle mitochrondria (sarcosomes), cytochrome c, and flight ability in the blowfly, Phormia regina. 2. During the 1st week of adult life, individual sarcosomes increase in mass from 2.7 x 10^–7 µg. dry weight at the time of emergence, to 8.5 x 10^–7 µg. by the 7th day. During this period of growth, the number of sarcosomes per fly (6.7 x 10⁸) remains constant. When mature, the sarcosomes account for 32.6 per cent of the total muscle dry weight, or close to 40 per cent on a wet weight basis. 3. It appears probable that the high content of flight muscle cytochromes is entirely localized in the sarcosomes. The cytochromes continue to be synthesized and increase in titer within the sarcosomes for 7 days after adult emergence. 4. As determined spectroscopically, the various cytochrome components at all times maintain a constant ratio both to one another and to the sarcosomal dry weight. This suggests the possibility that the cytochrome system may be synthesized as a single entity. 5. The wing-beat frequency of Drosophila funebris and Phormia varies with the age of these flies, being lowest at the time of emergence and maximum after the 6th day. 6. The relations between wing-beat frequency, respiration during flight, and sarcosomal cytochrome c content are discussed. On the basis of some likely assumptions it is calculated that the cytrochrome c turnover number is over 5,000, and that the cytochrome c turns over once for every two wing-beat cycles.     

Locust flight oscillator: Changes in motor output by certain pharmacological agents

The cholinesterase inhibitor eserine (physostigmine) causes a marked slowing of the wing-beat frequency of Locusta during the period from 4 to 16 hr after injection. The normal wing-beat frequency is attained again within 20 to 24 hr. The phase relationship of the antagonistic muscles involved in flight is changed during eserine-slowing of flight. d-Tubocurarine and acetylcholine also have slowing effects on flight. Their onset of action is rapid and their effects are reversed within 2 hr. Eserine in particular should be a useful tool for temporarily altering certain parameters of the flight motor pattern.     

Estimating the relative fitness of local adaptive peaks: the aerodynamic costs of flight in mimetic passion-vine butterflies Heliconius

In a related paper, we demonstrated that mimetic Heliconius butterflies have converged in wing-beat frequency and degree of asymmetry in the wing motion, whereas sister species are dissimilar in these same traits. Warning signals of sympatric, distasteful species converge in evolutionary models in order to educate their predators more efficiently that the signal is associated with unprofitable prey. Barring other constraints, the behaviours of the different co-mimetic pairs should ultimately converge on that behaviour which minimizes the energetic cost of flight. We estimated the energetic cost of each mimic''s flight behaviour in order to predict the difference in height of each fitness peak and the direction of convergent selection qualitatively. Following adjustments for body mass, mimetic Heliconius melpomene and Heliconius erato required more aerodynamic power than Heliconius cydno and Heliconius sapho. This difference was attributed to the slower flight speeds and higher wing-beat frequencies of H. melpomene and H. erato. Consequently, H. melpomene and H. erato expended more energy per unit distance per unit body mass than H. cydno and H. sapho. However, differences in body mass may equalize energy budgets and stabilize the sympatric coexistence of the two pairs of co-mimics.     

Effects of temperature on properties of flight neurons in the locust

High ambient temperatures increase the wing-beat frequency in flying locusts, Locusta migratoria. We investigated parameters of circuit and cellular properties of flight motoneurons at temperatures permissive for flight (20–40 °C). As the thoracic temperature increased motoneuronal conduction velocity increased from an average of 4.40 m/s at 25 °C to 6.73 m/s at 35 °C, and the membrane time constant decreased from 11.45 ms to 7.52 ms. These property changes may increase locust wing-beat frequency by affecting the temporal summation of inputs to flight neurons in the central circuitry. Increases in thoracic temperature from 25–35 °C also resulted in a hyperpolarization of the resting membrane potentials of flight motoneurons from an average of-41.1 mV to -47.5 mV, and a decrease of input resistances from an average of 3.45 M to 2.00 M. Temperature affected the measured input resistance both by affecting membrane properties, and by altering synaptic input. We suggest that the increase in conduction velocity Q₁₀=1.53) and the decrease of membrane time constant (Q₁₀=0.62) would more than account for the wing-beat frequency increase (Q₁₀=1.15). Hyperpolarization of the resting membrane potential (Q₁₀=1.18) and reduction in input resistance (Q₁₀=0.54) may be involved in automatic compensation of temperature effects.Abbreviations ANOVA analysis of variance - CPG central pattern generator - DL dorsal longitudinal muscles - EMG electromyographic - MN motoneuron - PSP post synaptic potential - Q₁₀ temperature coefficient - RMP resting membrane potential - S.D. standard deviation - SR stretch receptor     

Temperature dependence of auditory thresholds in two Central European anurans, Bombina variegata variegata (L.) and Rana ridibunda ridibunda Pall. (Amphibia), and its relation to calling

We recorded multi-unit activity from the torus semicircularis in two European anurans, to test for temperature dependence of the auditory thresholds. In Rana r. ridibunda the entire threshold-vs.-frequency curve shifts downward for a temperature increase from 5° to 15° C; the average increase in sensitivity is 14 dB. In Bombina v. variegata the increase in sensitivity averages 8 dB for a rise in temperature from 12° to 20° C; in addition, the best frequency is shifted by about 150 Hz by this increase in temperature, from 350—400 Hz to 550 Hz. The audiogram of Rana r. ridibunda differs from that of Bombina v. variegata in that it is markedly trimodal; the sensitivity maxima for Rana fall at 300—500 Hz, 750–1000 Hz and 1250–1700 Hz.     

Wing-beat frequencies,wing-areas and masses of flying insects and hummingbirds

A simple equation that relates the observed wing-beat frequencies f, the wing areas A, and the masses m of flying (especially hovering) insects and hummingbirds is found to be remarkably accurate over a mass ratio of 10⁴. There is some evidence that it is approximately correct for other birds over another two orders of magnitude of the mass. The equation also predicts a relation between f, A and m for flying animals that have evolved at higher altitudes.     

An ultrastructural study of tettigoniid muscle in relation to function

The modian dorsal longitudinal indirect flight muscles from the mesothorax and metathorax of Homorocoryphus nitidulus vicinus have been studied to determine whether structural differences might offer an explanation for reports that the mesothoracic musculature effects a wing-beat rate of 140 beats/sec during stridulation, whereas during flight, it, like that of the metathorax, effects wing-beat frequencies of 14 to 20 beats/sec. No differences were observed and it is concluded that the high wing-beat rate, reported during stridulation, is not reflected in any specific modification of mesothoracic muscle fine structure.     

Spiders of the genus Cupiennius Simon 1891 (Araneae,Ctenidae)

Summary Cupiennius salei (Ctenidae) is a tropical wandering spider which lives in close association with a particular type of plant (see companion paper). These plants are the channels through which the spiders receive and emit various types of vibrations. We measured the vibrations the spiders are typically exposed to when they sit on their dwelling plants (banana plant, bromeliad) in their natural biotope in Central America. In addition a laboratory analysis was carried out to get an approximate idea of the complex vibration-propagating properties of the dwelling plants, taking a banana plant as an example. (1) Types of vibrations (Figs. 1–4). Despite variability in detail there are characteristic differences in spectral composition between the vibrations of various abiotic and biotic origins: (a) Vibrations due to wind are very low frequency phenomena. Their frequency spectra are conspicuously narrow with prominent peaks close to or, more often, below 10 Hz. Vibrations due to raindrops show maximal acceleration values at ca. 1000 Hz. Their frequency band at-20 dB extends up to ca. 250 Hz where-as that of the vibrations due to wind extends to only ca. 50 Hz. (b) The frequency spectra of prey vibrations such as those generated by a running cockroach are typically broad-banded and contain high frequencies; they have largest peaks mostly between ca. 400 and 900 Hz. Their-20 dB frequency bands usually extend from a few Hz to ca. 900 Hz. Some potential prey animals such as grass-hoppers seem to be vibrocryptic; they walk by the spider as if unnoticed. Their cautious gait leads to only weak vibrations at very low frequencies resembling the background noise due to wind. Courtship signals are composed maily of low frequencies, intermediate between background noise and prey vibrations (male: prominent peaks at ca. 75 Hz and ca. 115 Hz; female: dominant frequencies between ca. 20 Hz and ca. 50 Hz). The male signal is composed of syllables and differs from all other vibrations studied here by being temporally highly ordered. A comparison with previous electrophysiological studies suggests that the high pass characteristics of the vibration receptors enhance the signal-to-(abiotic)-noise ratio and that the vibration-sensitive interneurons so far examined and found to have band pass characteristics are tuned to the frequencies found in the vibrations of biotic origin. (2) Signal propagation (Fig. 5). In terms of frequency-dependent attenuation of vibrations the banana plant is well suited for transmitting the above signals. Average attenuation values are ca. 0.35 dB/cm. Together with known data on vibration receptor sensitivity this explains the range of courtship signals of more than 1 m observed in behavioral studies. Attenuation in the plant is neither a monotonic function of frequency nor of distance from the signal source.     

Effect of Calcium, Temperature, and Polarizing Currents upon Alternating Current Excitation of Space-Clamped Squid Axons

Alternating current threshold excitation of space-clamped squid giant axons was measured as a function of frequency, external calcium concentration, temperature (from 10° to 35°C), and hyper- and depolarizing steps. In normal axons there is usually an optimum frequency at about 120 Hz, at which the threshold is a minimum. The threshold rises at both lower and higher frequencies to give a resonance curve. Low calcium causes an increase in optimum frequency, a decrease in current threshold, and an increase in sharpness of tuning in both real axons and axons computed according to the Hodgkin-Huxley formulation; high calcium causes opposite effects. An increase in temperature causes an increase of optimum frequency, an increase in sharpness of tuning, and an increase in threshold current in both real and computed axons. The Q₁₀ for the effect of temperature upon optimum frequency is 1.8 in real and computed axons at moderate temperatures. Hyperpolarization causes (a) a decrease in optimum frequency, (b) a decrease in sharpness of tuning, and (c) an increase in threshold. Depolarization causes opposite effects.     

Post-larval development of two rhythmical behavioural patterns: flight and song in the grasshopper,Omocestus viridulusS*

The ontogeny of two rhythmical outputs, wing-beat in flight and leg stroke in stridulation, was followed during post-larval development of the grasshopper 0.viridulus, The wing-beat frequency increases by a factor of c. 2; the repetition rate of the leg strokes remains constant. These results are discussed with respect to a hypothesis of neuronal economy within the CNS, and their biological significance.     

The effect of temperature on the swimming of a teleost (Clupea harengus) and an ascidian larva (Dendrodoa grossularia)

• 1.1. Using a high-speed video system operating at 400 frames/sec, the effects of temperature on tail beat frequency, swimming speed and stride length were examined in newly hatched larvae of herring (Clupea harengus L.) and in tadpole larvae of the ascidian Dendrodoa grossularia van Beneden.
• 2.2. The effect of temperature was linear; the tail beat frequency of 8 mm-long herring larvae increased from 19 Hz at 5.6°C to 37 Hz at 14.9°C (Q₁₀ = 2.04); that of 2 mm-long Dendrodoa larvae increased from 10 Hz at 9.6°C to 23 Hz at 18.1°C (Q₁₀ = 2.52).
• 3.3. Burst swimming speeds of herring larvae increased from 80 mm/sec at 5°C to 150 mm/sec at 15°C, stride length remaining constant at about 0.5 of the body length for each tail beat.
• 4.4. More continuous swimming of Dendrodoa increased from 4.0 mm/sec at 10°C to 11.5 mm/sec at 18°C, the stride length increasing from about 0.15 to 0.25.

     

Dynamic Rheooptical Behavior of Isolated Bovine Cornea

The dynamic Young's modulus E′ and loss modulus E″ were obtained for isolated bovine cornea using a direct-reading dynamic viscoelastometer. Within the temperature range (0-60°C) and frequency range (3.5-110 Hz) studied, both moduli were temperature and frequency independent. The dynamic birefringence of the cornea was measured in a special apparatus designed for this purpose in conjunction with the dynamic viscoelastometer. The stress-optical and strain-optical coefficients as well as the corresponding phase angles were evaluated as a function of temperature and frequency. The strain- and stress-optical coefficients were both temperature and frequency dependent.     

Temperature and auditory thresholds: Bioacoustic studies of the frogsRana r. ridibunda,Hyla a. arborea andHyla a. savignyi (Anura,amphibia)

Summary The auditory thresholds of three frogs-two subspecies of the genusHyla (H. a. arborea, H. a. savignyi) and one of the genusRana (R. r. ridibunda)—were measured at 5°, 12°, 20° and 28°C, by recording multi-unit activity from the torus semicircularis. In the tree frogs, the upper limit of the audible range is 7,000 Hz. At 5°C the best frequency is 3,000 Hz; the threshold (expressed in dB SPL in all cases) at this frequency is 49 dB (males) and 43 dB (females) forH. a. arborea and 42 dB (males) and 48 dB (females) forH. a. savignyi. At 12°C the thresholds are lower, and they are lower still at 20°, reaching a minimum, at 3,000 Hz, of 42 dB (males) and 38 dB (females) forH. a. arborea and 41 dB (males) and 40 dB (females) forH. a. savignyi. At frequencies of 1,000 Hz and lower, thresholds are high at 5°C; in part of this range they are considerably lowered at 20°C, whereas at 28°C there is a reduction in sensitivity to most frequencies inH. a. arborea, amounting to more than 10 dB in the males.H. a. savignyi differs in this regard; at 28° sensitivity is no less than at lower temperatures, and in fact is greater in the range 1,000–1,400 Hz. The audible range ofR. r. ridibunda is more restricted than that of the tree frogs, but it is more sensitive within this range. The highest frequency is 4,500 Hz. At 5°C the thresholds of the males are lowest at 500–600 Hz (42 dB) and 1,400–1,900 Hz (ca. 39 dB). The best frequencies of the females are 700 Hz (38 dB) and 1,400 Hz (36 dB). At 12°C the thresholds at 300 Hz and 1,000 Hz are markedly lowered, by 10–18 dB. The thresholds of the females at 20°C are still lower over almost the entire audible range, whereas in the males only part of the range is affected. This difference persists at 28°C, the threshold curve of the males being slightly raised, while that of the females is unchanged. Latencies are dependent upon temperature and sound pressure. With a rise in temperature from 5° to 20°C the latency falls by ca. 8 ms. An increase in sound pressure from 5 dB to 30 dB SPL shortens the latency by ca. 10 ms. These changes were found in all the frogs studied.     

Population-specific behavioral electrosensitivity of the European blind cave salamander,Proteus anguinus

In nine salamanders from different Slovenian populations of the urodele Proteus anguinus, including three specimens of its ‘black’ variety, P anguinus parkelj, thresholds of an overt avoidance response to electrical field stimuli were estimated as a function of frequency (continuous sine-waves in water). Thresholds down to 0.3 mV/cm (ca 100 nA/cm²) and up to 2 mV/cm (670 nA/cm²), at ‘best frequencies’ of around 30 Hz were found. Sensitivity covered a total frequency range of below 1 Hz, excluding DC, up to 1–2 kHz with up to 40 dB higher thresholds. Thresholds and tuning curves are compared with those of a Proteus population raised in captivity for more than 35 years. The biological significance and the apparently still ongoing evolution of the electrical sense in urodeles, ie in the genus Proteus, are interpreted in terms of comparative sensory physiology and ethological ecology as a result of more recent evolutionary diversification during and since glaciation in the Pleistocene.     

Dynamic mechanical properties of the tissue-engineered matrix associated with individual chondrocytes

The success of cell-based tissue engineering approaches in restoring biological function will be facilitated by a comprehensive fundamental knowledge of the temporal evolution of the structure and properties of the newly synthesized matrix. Here, we quantify the dynamic oscillatory mechanical behavior of the engineered matrix associated with individual chondrocytes cultured in vitro for up to 28 days in alginate scaffolds. The magnitude of the complex modulus (|E*|) and phase shift (δ) were measured in culture medium using Atomic Force Microscopy (AFM)-based nanoindentation in response to an imposed oscillatory deformation (amplitude ～5 nm) as a function of frequency (f=1–316 Hz), probe tip geometry (2.5 μm radius sphere and 50 nm radius square pyramid), and in the absence and presence of growth factors (GF, insulin growth factor-1, IGF-1, and osteogenic protein-1, OP-1). |E*| for all conditions increased nonlinearly with frequency dependence approximately f^1/2 and ranged between ～1 and 25 kPa. This result, along with theoretical calculations of the characteristic poroelastic relaxation frequency, f_p, (～50–90 Hz) suggested that this time-dependent behavior was governed primarily by fluid flow-dependent poroelasticity, rather than flow-independent viscoelastic processes associated with the solid matrix. |E*(f)| increased, (f) decreased, and the hydraulic permeability, k, decreased with time in culture and with growth factor treatment. This trend of a more elastic-like response was thought to be associated with increased macromolecular biosynthesis, density, and a more mature matrix structure/organization.     

Propagation direction of natural mechanical oscillations in the biceps brachii muscle during voluntary contraction

The aim of the study was to determine the directionality of the coupling of mechanical vibrations across the biceps brachii muscle at different frequencies of interest during voluntary contraction. The vibrations that are naturally generated by skeletal muscles were recorded by a two-dimensional array of skin mounted accelerometers over the biceps brachii muscle (surface mechanomyogram, S-MMG) during voluntary isometric contractions in ten healthy young men. As a measure of the similarity of vibration between a given pair of accelerometers, the spatial coherence of S-MMG at low (f < 25 Hz) and high (f > 25 Hz) frequency bands were investigated to determine if the coupling of the natural mechanical vibrations were due to the different physiological muscle activity at low and high frequencies. In both frequency bands, spatial coherence values for sensor pairs aligned longitudinally along the proximal to distal ends of the biceps were significantly higher compared with those for the sensor pairs oriented perpendicular to the muscle fibers. This difference was more evident at the higher frequency band. The findings indicated that coherent mechanical oscillations mainly propagated along the longitudinal direction of the biceps brachii muscle fibers at high frequencies (f > 25 Hz).     

Evolutionary and neurobiological implications of selective phonotaxis in the spring peeper (Hyla crucifer)

Males of the spring peeper (Hyla crucifer) in central Missouri produce frequency-modulated, sinusoidal advertisement calls with a duration of 90–250 ms, and a mid-point frequency of 2800–3360 Hz. The frequency of the call is inversely correlated with body size. In playback experiments with synthetic stimuli, females did not prefer a frequency-modulated call to a call of constant frequency. Females preferred a call with a duration of 150 ms to sounds with durations of 40, 75 and 400 ms; a call of 300 ms was just as attractive as the 150-ms call. Females preferred a call of 2875 Hz to alternatives of 4000 Hz and 2600 Hz. The auditory system of H. crucifer is thus only roughly tuned to the temporal and spectral properties of the advertisement call. The female's specificity with respect to duration alone is adequate for species recognition, but intraspecific mate choice based on call frequency is extremely unlikely.     

Anti-predator Fan-blowing in Guard Bees, <Emphasis Type="Italic">Apis mellifera capensis</Emphasis> Esch

Honeybees employ different defensive strategies depending on the nature of potential predators. The Cape honeybee, Apis mellifera capensis, exhibits a unique fan-blowing behaviour to repel ants and similar sized insects at the nest entrance. Guard bees turn in alternating clockwise and anticlockwise circles on a fixed vertical axis and fan their wings when encountering tramp ants (Pheidole megacephala), aphids (Myzus persicae) and termites (Trinervitermes trinovoides) on the landing board of a hive. The blowing force was constant and was driven by fanning with a wing-beat frequency of 274.8 ± 16.3 Hz, which exceeds that of flight. On the contrary, small hive beetles (Aethina tumida) were removed by mauling and expulsion whereas larvae of the greater waxmoth (Galleria mellonella) and the mealworm (Tenebrio molitor) were seized with mandibles and thrown from the nest area.