Effect of temperature upon auditory thresholds in two anuran species,Bombina v. variegata andAlytes o. obstetricans (Amphibia,Discoglossidae)

Summary Because it seemed likely that temperature affects not only the calling mechanism of anurans, but their auditory systems as well, we have measured the thresholds ofBombina variegata variegata andAlytes obstetricans obstetricans at 5°, 12°, 20° and 28°C by recording multiple-unit activity from the torus semicircularis. An increase in temperature from 5° to 28°C shortened the latencies considerably. InBombina v. variegata latencies fell from an average of 32 ms to 13 ms (600 Hz), and inAlytes o. obstetricans from an average of 22 ms to 11 ms (500 Hz). At frequencies below 500 Hz the decrease was still greater. Latency was also dependent on frequency, being shorter with high-frequency tones. At 5°C the auditory neurons ofBombina are rather insensitive and respond irregularly. At 12°C and at 20°C sensitivity is markedly increased. The minimum threshold in males was at 400–500 Hz (49 dB SPL), and that of females was at 450 Hz (47 dB SPL). There was no further increase in sensitivity at 28°C. InAlytes the auditory neurons were fully functional even at 5°C. At this temperature the audiogram had sensitivity maxima at 300, 1,100–1,300 and 1,800 Hz. In both males and females an increase in temperature to 20°C caused an extraordinary increase in sensitivity, primarily in the low-frequency range; the minimum threshold, at 400 Hz, was 44 dB SPL in males and 41 dB SPL in famales. In the intermediate frequency range there was also a marked increase in sensitivity, but not in the high-frequency range, where the best frequency was 1,800 Hz. At 28°C the threshold to low-frequency tones was increased.     

Temperature dependence of oocyte cleavage in three thermophilically different frogs of the genus Rana

The duration of the mitotic cycle (τ₀) at different temperatures at the time of synchronous cleavage division of oocytes of frogs Rana temporaria L., Rana arvalis Nilss. (= Rana terrestris Andr.) and Rana ridibunda Pall. has been studied. The first species is the least, and the last the most, thermophilic. In the semilogarithmic scale, the dependence of τ₀ on temperature is linear in the middle of the temperature scale, and is limited on both sides by inflexion points. This zone comprises the temperatures at which the larvae develop normally. For R. temporaria these temperatures are between 11–23°C. for R. arvalis 13–24°C and for R. ridibunda 16–27°C. At the midpoints of each zone (17.5, 18.5 and 21.5°C respectively) there is no difference in τ₀ between the species. At the same temperature, however, the mitotic cycle is the shortest for R. temporaria, is somewhat longer for R. arvalis and is the longest for R. ridibunda. The difference in the optimal temperature zones agree with different thermal stabilities of the cells and proteins of these species.     

Temperature dependence of visual fusion frequency in Rana lessonae cam., Bufo bufo L. and Bombina bombina (L.) (Amphibia)

The electroretinogram (ERG) was used to measure the flicker-fusion frequencies of Rana lessonae, Bufo bufo and Bombina bombina over the temperature range 5–25°C. In all three species the fusion frequency increased with increasing temperature. In the intermediate range of temperatures, the fusion frequencies of Rana lessonae and Bombina bombina doubled when the temperature was raised by 10°C.     

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.     

Laich-Fressen durch Kaulquappen als mögliche Ursache spezifischer Biotoppräferenzen und kurzer Laichzeiten bei europäischen Froschlurchen (Amphibia,Anura)

Zusammenfassung In einem Kunstweiher aufgezogene Kaulquappen von Rana temporaria fressen in der Versuchsanordnung von Abb. I den Laich folgender sympatrischer Anuren-Arten: Rana temporaria (Kannibalismus), Rana esculenta, Rana ridibunda, Bufo bufo, Bufo calamita, Bombina variegata und Hyla arborea (Laichräubern). — Daß die Kaulquappen der früh im Jahr laichenden Rana temporaria später gelegten arteigenen und artfremden Laich fressen, wirkt als Selektionsdruck in folgende Richtungen: Rana temporaria züchtet sich selbst eine kurze Laichzeit. Spät in seichtem Wasser laichende Arten werden im Biotop von Rana temporaria unterdrückt (Bombina variegata, Bufo calamita, Hyla arborea). Rana esculenta, Rana ridibunda und Bufo bufo sind dem Laichräubern durch Kaulquappen wenig ausgesetzt, weil sie in größeren Wassertiefen laichen. Zudem ist Bufo bufo ebenfalls ein Frühlaicher. Alytes obstetricans steht außer Konkurrenz, weil er die Eier nicht ins Wasser setzt. — Untersuchungen über die Biotoppräferenzen und Laichzeiten der betroffenen Arten bestätigen diese Interpretation.

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Summary Tadpoles of Rana temporaria which have been raised in an artificial pond prey in the experimental situation shown in Fig. 1 upon the spawn of the following sympatric European Anura species: Rana temporaria (cannibalism), Rana esculenta, Rana ridibunda, Bufo bufo, Bufo calamita, Bombina variegata and Hyla arborea (predation). — Rana temporaria is an early breeder. Thus selection pressure acts in the following ways: Rana temporaria establishes for itself an explosive breeding pattern. Species which breed later in the year in shallow water are suppressed in the biotope of Rana temporaria and develop other biotope preferences (Bombina variegata, Bufo calamita, Hyla arborea). Rana esculenta, Rana ridibunda and Bufo bufo spawn in deeper water. Therefore they are scarcely exposed to the tadpoles of Rana temporaria. Moreover Bufo bufo, too, is an early breeder. Alytes obstetricans laying no spawn in the water is not endangered. — An analysis of biotope preferences and breeding times of the species involved confirms these interpretations.

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Mit Unterstützung des Schweizerischen Nationalfonds zur Förderung der wissenschaftlichen Forschung.     

The Vascularization of the Kidneys in Bufo bufo (L.), Bombina variegata (L.), Rana ridibunda (L.) and Xenopus laevis (D.) (Amphibia,Anura) as Revealed by Scanning Electron Microscopy of Vascular Corrosion Casts

Abstract The vascular patterns of the ventral side of the kidneys in Bufo bufo and Rana ridibunda is similar. Strong venulae renales revehentes dominate. In Bombina variegata and Xenopus laevis, however, also many superficially located glomeruli are found at the ventral side. In Xenopus further branching of the renal arteries into afferent arterioles attracts attention. Bundles of delicate afferent arterioles originate within circumscribed areas of the renal artery. The glomerular layer of the kidney is tightest in Bombina, and has its maximal extension in Rana. It covers up to 2/3 of the thickness of the kidney while in the other species studied the glomeruli are restricted to the ventral third of the kidney. Glomeruli with double afferent or efferent arterioles were rarely found in Xenopus. The vascularization of the dorsal side of the kidneys is characterized by the presence of large (Bufo, Rana, Xenopus) or small (Bombina) venulae renales advehentes.     

Temperature tolerances in the Namib Desert dune ant, Camponotus detritus

The mean preferred temperature of workers and brood of Camponotus detritus was 35°C at 100% r.h. and 31–33°C at 30% r.h. The critical maximal temperature of workers was 53°C at both 100% r.h. and 30% r.h. while the critical minimal temperature was 4.57°C at 100% r.h. Workers tolerated ?1°C and 95% r.h.; 45°C and 95% r.h. and 45°C and 45% r.h. for 24 h.     

Temperature and salinity tolerances of larval Californian grunion, Leuresthes tenuis (Ayres): A comparison with gulf grunion, L. Sardina (Jenkins & Evermann)

Temperature and salinity tolerances were determined for larval California grunion, Leuresthes tenuis (Ayres), and compared with previous data for Gulf of California grunion, L. sardina (Jenkins & Evermann). Larvae of similar age and acclimation history showed little interspecific difference in thermal tolerance, as measured by half-hour LT₅₀ values for 20–30 day old late postlarvae acclimated at various temperatures, and by upper and lower incipient lethal temperatures for 18°C-acclimated prolarvae. The upper incipient lethal temperature differed by 1 deg.-C (32°C for L. tenuis, 31°C for L. sardina), while the lower incipient lethal temperature for the 18°C acclimated prolarvae of both species was 7.5°C. L. tenuis larvae were much less euryhaline than L. sardina, with incipient lethal salinities of 4.2–41 %. for prolarvae and 8.6–38 %. for 20-day-old postlarvae; comparable values for L. sardina are 4–67.5 %. and 5–57.5 %. Both species show a decrease in temperature and salinity tolerance with age. The larvae of these disjunct congeners show a significant physiological divergence in euryhalinity but not in overall temperature tolerance. These tolerances are discussed in relation to the respective geographic ranges and behavioral responses of the two species.     

Observations on the morphology and infectivity for cattle of Babesia bovis parasites in unfed Boophilus microplus larvae after incubation at various temperatures

Dalgliesh R. J. and Stewart N. P. 1979. Observations on the morphology and infectivity for cattle of Babesia bovis parasites in unfed Boophilus microplus larvae after incubation at various temperatures. International Journal for Parasitology9: 115–120. The temperature of incubation of unfed Boophilus microplus larvae infected with Babesia bovis influenced the morphology and infectivity of the Babesia within the tick. Incubation at 37°C for 1–3 days stimulated the development of parasites morphologically similar to those usually observed in fed larvae harvested from cattle; similar forms appeared more slowly in larvae incubated at 31°C or 25°C. Extracts prepared from larvae after incubation at 37°C for 3–5 days or 30°C for 8 days were consistently infective for cattle. Prior storage of larvae at 14°C for up to 28 days enhanced the development of infectivity at 37°C; infectivity could still be produced after 65 days storage at 14°C but not after 76 days. Larvae released on a host transmitted B. bovis sooner if they had been incubated at 37°C for 4 days. It was concluded that the development of B. bovis to an infective stage in B. microplus is temperature dependent and does not require the stimulus of feeding by the host.     

DNS-Gehalt und Chromosomenstruktur bei Amphibien

Comparative karyotype analysis and cytophotometric DNA measurements on further amphibian species (Hyla arborea, Bombina variegata, B. bombina, Triturus vulgaris, T. alpestris, and Salamandra salamandra) were carried out. The relative DNA values of the genomes determined for these species and other amphibians investigated earlier (Ullerich, 1966, 1967), already do nearly exclude the hypothesis that the interspecific differences in DNA content in frogs, toads, and salamanders are caused by differential polynemy of their chromosomes. Electron microscopic investigations on the DNA axes of lampbrush chromosomes of Bufo calamita, B. viridis, B. bufo, Rana esculenta, Bombina variegata, and Triturus alpestris treated with trypsin and ribonuclease confirm that the chromosomes of these species are not polynemic; in all species analysed the lampbrush chromosomes consist of the same number of DNA strands. The double-strandedness observed regularly in several segments of the chromatid axes in the loops as well as in the interchromomeric regions of all species suggest that the chromatids possibly are divided into half-chromatids. The minimum diameter of these two deoxyribonuclease-sensitive fibrills is 20–35 Å, whereas the chromatid axes in those segments which do not show double-strandedness mostly measure 40–65 Å. The high DNA amounts and interspecific differences in DNA content in the amphibian species analysed, probably in all amphibians, therefore must be caused during evolutionary processes by local increase (perhaps in a smaller extent also by-local decrease) in DNA in the chromosomes.     

Mating calls of water frogs (Ranidae) from Lake Skutari,Yugoslavia, and the relationship to water frogs of other regions1

According to the results of a bioacoustic analysis of the mating calls recorded at the northern end of Lake Skutari, Yugoslavia, this region is inhabited by three water frog phenotypes: Rana ridibunda, R. lessonae and hybrids of these two species. The mating call of R. ridibunda consists of an average of 3.55 pulse groups at all water temperatures. Other parameters of the call, however, are greatly influenced by temperature. The conclusion that the second phenotype is the species R. lessonae was based on the characteristics of the mating call. At a water temperature of 20°C, a call consists of 29 pulse groups repeated at a rate of 24 Hz. Analysis revealed almost complete agreement between this mating call and those of Central and Eastern European R. lessonae. The systematic implications of this finding are discussed. The mating calls of the hybrids of R. ridibunda and R. lessonae are intermediate between those of the parents.     

Some effects of time,temperature and feeding on infection rates with Babesia bovis and Babesia bigemina in Boophilus microplus larvae

Dalgliesh R. J. and Stewart N. P. 1982. Some effects of time, temperature and feeding on infection rates with Babesia bovis and Babesia bigemina in Boophilus microplus larvae. International Journal for Parasitology12: 323–326. Percentages of larval ticks in which Babesia bovis and B. bigemina parasites could be detected (infection rates) were determined after the larvae had been exposed to temperatures between 9°C and 27°C for periods of 1–35 days and then either fed on calves or heated at 37°C to stimulate babesial development. Infection rates with both species increased during 2–4 weeks after the larvae hatched, regardless of the temperature of exposure. Infection rates with B. bovis were higher after exposure of larvae to 14°C than to 27°C. This effect was less pronounced with B. bigemina. Infection rates were higher in fed larvae than in unfed, ‘heat stimulated’ larvae. The findings indicate that infected larval ticks become more efficient vectors of Babesia during the first 2–4 weeks after hatching and that repeated sampling of a tick population is necessary to determine valid infection rates.     

Heat resistance of the skeletal muscle in Western Palearctic green frogs (<Emphasis Type="Italic">Rana esculenta</Emphasis> complex)

Heat resistance of the gastrocnemius muscle was studied in five species of the Rana esculenta complex. It was similar in R. bedriagae, R. lessonae, and in the European form of R. ridibunda; while North African R. saharica demonstrated a lower heat resistance. No heterosis was expressed in R. esculenta, a clonal hybrid of R. lessonae and R. ridibunda, for the heat resistance of the muscle. Moreover, this species demonstrated low heat resistance at the highest test temperature (42°C). Comparison of diploid and triploid R. esculenta syntopically occurring in the same water bodies demonstrated no differences between them, thus, suggesting that polyploidy has no effect on this parameter at least in this case.     

Effects of varying temperature on the reproduction and damage potential of Heterodera schachtii to Chinese cabbage (Brassica rapa pekinensis)

Heterodera schachtii is a well-known, destructive pathogen of Chinese cabbage (Brassica rapa pekinensis) in Korea, and several studies have attempted to find a potential control measure against it. This study is the first to investigate the effects of varying temperature on the reproduction and damage potential of H. schachtii to Chinese cabbage. Chinese cabbage plants were inoculated with H. schachtii at different densities (1, 2, or 4 juveniles per gram of soil) and grown under three temperature regimes: constant (15, 20, or 25 °C), increasing (10, 14, and 18 °C), and fluctuating (positive, 16.7–22.0 °C; negative, 21.5–11.5 °C). At a constant temperature after 30 days of inoculation, both Chinese cabbage and H. schachtii performed best at 20 °C. However, after 60 days of inoculation, H. schachtii had a significantly higher population at 20 °C, whereas cabbage growth was best at 25 °C. With increasing temperature, the numbers of cysts and females did not change significantly, and reached maxima at an initial temperature of 14 °C. However, the number of leaves and weights of the Chinese cabbage plants significantly differed at 14 °C. Under fluctuating temperatures, temperature decreases reduced the H. schachtii population.     

Pathogenesis and midgut histopathology of Bacillus thuringiensis in Simulium vittatum (Diptera: Simuliidae)

The pathogenesis and midgut histopathology which resulted when larvae of the blackfly, Simulium vittatum, were exposed to Bacillus thuringiensis at various temperatures and periods of exposure were investigated. The onset of mortality was studied at 10°, 15°, 19°, and 24°C. For each 4–5°C increase in temperature above 15°C, the onset of mortality was shortened by 24 hr. Exposures as brief as 15 min to 10 ppm of a whole spore preparation resulted in an average mortality of 29% in late-instar larvae. Mortality increased sharply for exposures up to 3 hr, approaching a maximum of 80%.The gross signs of disease included cessation of feeding and tetany with brachytosis. The tissue most affected was the midgut epithelium in the regions of the gastric caeca and posterior stomach. The formation of cytoplasmic vacuoles followed by cell lysis and/or sloughing were very apparent in moribund larvae. Death resulted without bacteremia.     

Effect of temperature and ionic environment on the specific binding of 3H(—)sulpiride to membranes from different rat brain regions

Sulpiride is an antipsychotic drug endowed with the properties of a dopamine antagonist. The failure of sulpiride to inhibit neostriatal dopamine stimulated adenylate cyclase activity indicated that this drug is a selective D₂ receptor antagonist. In this study we used a novel synthesized ²H(—)sulpiride with very high specific activity (72 Ci/mol) and characterized the temperature sensitivity of the binding sites labeled by this compound. Kinetic analysis of ³H(—)sulpiride binding in rat striatum showed unstable behavior when incubation was performed at 37 or 30°C. However when experiments were carried out at 15 or 10°C, binding reached a stable steady-state within 10 min. Scatchard analysis of binding isotherms obtained at 10°C showed a 5-fold increase in the maximum number of binding sites and a decrease in K_d values to one-third those obtained at 37°C. Pharmacological characterization of the binding sites labeled by ³H(—)sulpiride at 10°C showed a greater affinity for antagonists but not for agonists than 37°C. Under both experimental condition, ³H(—)sulpiride binding sites were Na⁺ and GTP-sensitive. The temperature sensitive binding phenomenon appeared to be area specific. ³H(—)sulpiride binding sites in tissues other than from striatum were influenced less or not at all by changes in incubation temperature.     

The mating call of hybrids of the fire-bellied toad and yellow-bellied toad (Bombina bombina (L.), Bombina v. variegata (L.), discoglossidae,anura)

Summary Male hybrids obtained by crossing Bombina bombina with Bombina v. variegata displayed calling behavior when treated with hormones at the age of about 12 months. The mating calls of the hybrids are intermediate with respect to rate, duration, inter-call interval, and fundamental frequency between the calls of the two purebred species.     

Mass production,infectivity, and field application studies with the entomogenous fungus Paecilomyces farinosus

Hyphal bodies (HB) of the entomogenous fungus Paecilomyces farinosus mass produced in shaken liquid cultures are infective per os and topically to Spodoptera exigua larvae. Pathogenicity of HB was greatest at pH 5.5. It was reduced by exposure for more than one-half hour to temperatures above 30°C. P. farinosus infected, killed, and produced mycelia on the surface of first-instar S. exigua larvae at a temperature—relative humidity combination as low at 15°C and 70% RH. Using two types of microdroplet applicators (droplet in the size range 1–30 and 30–90 μm, respectively) under field conditions, HB were delivered to distances of 76 m from the site of spraying. The number of HB deposited on the leaf surfaces of treated crops caused mortality of 70 to 90% in bioassayed larvae.