A Simple Device for Producing Harmonic Temperature Fluctuations

1962 ◽  
Vol 94 (9) ◽  
pp. 1002-1005
Author(s):  
Gary B. Pitman ◽  
Roger B. Ryan
Keyword(s):  
Constant Temperature ◽  
Temperature Fluctuations ◽  
Simple Device ◽  
Insect Development ◽  
Laboratory Studies ◽  
Natural Conditions ◽  
Temperature Conditions ◽  
Control Devices ◽  
Periodic Constant ◽  
Fluctuating Temperatures

Most laboratory studies of insect development have been conducted under constant temperature conditions. Since constant temperatures are rarely encountered under natural conditions, results of such studies are limited in their application. It is desirable to compare the effects of fluctuating temperatures and constant temperatures on insect development. For this purpose, control devices which produce regular alternations of periodic constant temperatures or continuously varying temperatures of a predictable nature are needed.

Effects of constant and fluctuating temperatures on egg production in the threespine stickleback (Gasterosteus aculeatus)

1989 ◽  
Vol 67 (6) ◽  
pp. 1599-1602 ◽  
Author(s):  
Vital Boulé ◽  
Gerard J. Fitzgerald
Keyword(s):  
Reproductive Performance ◽  
Egg Production ◽  
Egg Size ◽  
Laboratory Experiments ◽  
Gasterosteus Aculeatus ◽  
Reproduction Number ◽  
Temperature Fluctuations ◽  
Spawning Grounds ◽  
Threespine Sticklebacks ◽  
Fluctuating Temperatures

Female threespine sticklebacks (Gasterosteus aculeatus) spend only 9–15 days on the spawning grounds, an intertidal salt marsh at Isle Verte, Quebec, during a 2-month breeding season. Individuals average only one spawning. However, in the laboratory they lay clutches of several hundred eggs every 3–5 days for several months. We designed laboratory experiments to determine (i) whether daily temperature fluctuations similar to those encountered in the marsh affect reproduction (number of clutches, number of eggs per clutch, and size of eggs) and (ii) whether the amplitude of the fluctuations encountered by the fish affects reproduction. We compared the reproduction of females held in fluctuating temperatures with that of females kept at 20 °C. Fish kept under fluctuating conditions produced more eggs per clutch but had longer interspawning intervals than those at 20 °C. Total seasonal egg production and egg size did not differ between the two groups. Fish in fluctuating temperatures survived longer and were in better condition than those at 20 °C. We conclude that the amplitude of the fluctuations is less important than mean temperature in determining reproductive performance. Fluctuating temperatures on the spawning grounds are not responsible for the short residency there.

scholarly journals The differential transmissibility of myxoma virus strains of differing virulence grades by the rabbit flea Spilopsyllus cuniculi (Dale)

1975 ◽  
Vol 75 (2) ◽  
pp. 237-247 ◽  
Author(s):  
A. R. Mead-Briggs ◽  
J. A. Vaughan
Keyword(s):  
Host Resistance ◽  
Oryctolagus Cuniculus ◽  
Selective Advantage ◽  
Myxoma Virus ◽  
Laboratory Studies ◽  
Natural Conditions ◽  
Male And Female ◽  
The Mean ◽  
Virus Strains ◽  
Sampling Times

SUMMARYLaboratory studies showed that few rabbit fleas (Spilopsyllus cuniculi (Dale)) transmitted myxomatosis after removal from wild rabbits (Oryctolagus cuniculus (L)) that had been infected for fewer than 10–12 days, irrespective of the virulence of the myxoma virus strain involved. Rabbits infected with fully virulent (Grade I) strains died within 10–15 days and few fleas from these hosts became infective; averaging all the samples taken, 12% of the fleas were infective. Also, few fleas acquired infectivity on individual rabbits which recovered from infection with attenuated strains; the mean was 8% infective. Rabbits which died between 17 and 44 days after infection had higher proportions of infective fleas at all sampling times; the mean was 42% infective. Male and female fleas transmitted virus with equal efficiency.For rabbits infected with any of the attenuated virus strains the mean percentage of infective fleas was inversely related to the survival time of the host. Rabbits infected with moderately attenuated strains (Grades IIIA and IIIB) had, on average, the highest proportion of infective fleas; hence such strains have a selective advantage and have become predominant under natural conditions in Britain. The changes that might occur if there is an increase in host resistance to myxomatosis are discussed.

Temperature-based phenology model for predicting the present and future establishment and distribution of recently invasive Spodoptera frugiperda (J. E. Smith) in India

2021 ◽  
pp. 1-15
Author(s):  
T. V. Prasad ◽  
M. Srinivasa Rao ◽  
K. V. Rao ◽  
S. K. Bal ◽  
Y. Muttapa ◽  
...  
Keyword(s):  
Life Table ◽  
Constant Temperature ◽  
Spodoptera Frugiperda ◽  
Life Table Parameters ◽  
Invasive Insect ◽  
Temperature Conditions ◽  
Risk Indices ◽  
Survival And Reproduction ◽  
Temperature Ranges ◽  
Phenology Model

Abstract Fall armyworm, Spodoptera frugiperda (J. E. Smith) is a polyphagous and highly destructive invasive insect pest of many crops. It was recently introduced into India and widely reported in almost all parts of India. Development of a temperature-based phenology model for predicting its rate of development and distribution will help in understanding the establishment and further spread of introduced invasive insect pests. Development, survival and reproduction parameters of S. frugiperda at six constant temperature conditions (15, 20, 25, 27, 30 and 35°C) were investigated and further validated with data generated under fluctuating temperature conditions. The estimated lower developmental threshold temperatures were 12.1°C for eggs, 11°C for larvae, 12.2°C for pupae, 15.13°C for males and 12.66°C for females. Degree-day (DD) requirements for the development of the different stages of S. frugiperda were 50, 250 and 200 DD for egg, larva and pupa, respectively. The best-fitted functions were compiled for each life stage to yield a phenology model, which was stochastically simulated to estimate the life table parameters. The developed phenology model predicted temperature ranges between 27 and 30°C as favourable for S. frugiperda development, survival and reproduction. The results revealed that maximum net reproductive rate (215.66 females/female/generation) and total fecundity (981.08 individuals/female/generation) were attained at 30°C constant temperature. The mean length of generations decreased from 74.29 days at 15°C to 38.74 days at 30°C. The maximum intrinsic rate of increase (0.138 females/female/day) and shortest doubling time (4.9 days) were also observed at 30°C. Results of simulated life table parameters showed high temperature-dependent development of S. frugiperda and complete development within all the tested constant temperature ranges (15–35°C). Simulated life table parameters for predicting risk indices of S. frugiperda in India indicated a significant increase in activity indices and establishment risk indices with a higher number of generations during future (2050 and 2070) climatic change scenarios compared to present conditions. Our results indicate that India will be highly suitable for the establishment and survival of S. frugiperda in future time periods.

Laboratory studies on the larval biology of Simulium venustum Say (Diptera: Simuliidae)

1976 ◽  
Vol 54 (10) ◽  
pp. 1657-1663 ◽  
Author(s):  
Joseph E. Mokry
Keyword(s):  
Growth Rate ◽  
Growth Curves ◽  
Temperature Profiles ◽  
Laboratory Studies ◽  
Natural Conditions ◽  
Larval Biology ◽  
Temperature Growth ◽  
Complete Development ◽  
Blackfly Larvae ◽  
Pass Through

Larvae reared from field-collected eggs of Simulium venustum were found to pass through six larval instars. Temperature strongly affected both the growth rate of larvae and their survival. At 5, 10, and 12 °C all S. venustum larvae died before reaching the sixth instar. At 15 °C, larvae were found to be able to complete development to the sixth instar, although only 10.5% survived to this stage. Increases in temperature led to increases in survival and rate of growth, with the best survival (20.4%) at 22 °C; most larvae required 22 days to reach this stage. Above 22 °C, survival decreased (5.7%), although the growth rate continued to increase. A growth model for blackfly larvae simulating natural conditions was constructed using temperature–growth curves obtained in laboratory trials and comparing these data with stream temperature profiles.

A novel piezoelectric dynamometer based on double-sensor for thermal compensation

2016 ◽  
Vol 231 (23) ◽  
pp. 4479-4491 ◽  
Author(s):  
Yu Tian ◽  
Jun Zhang ◽  
Zong-jin Ren ◽  
Wei Liu ◽  
Zhenyuan Jia ◽  
...  
Keyword(s):  
Constant Temperature ◽  
Rocket Engine ◽  
Temperature Fluctuations ◽  
Measurement Precision ◽  
Thermal Compensation ◽  
Static Calibration ◽  
Maximal Output ◽  
Heat Conduction Differential Equation ◽  
Force Compensation ◽  
Over Time

A piezoelectric dynamometer can produce thermal forces because of temperature fluctuations, thus affecting measurement precision. To investigate the influence of the thermal force on the dynamometer, this article proposes a hypothesis of decreasing the conduction power and establishes the function of a thermal force over time in an ordinary dynamometer based on the heat conduction differential equation. A novel double-sensor thermal compensation dynamometer is designed, with static calibration in constant temperature and force/heat coupling experiments, to solve the problem of the thermal force. The experimental results indicate that the nonlinearity and repeatability of the double-sensor thermal compensation dynamometer are less than 1% full scale (FS) of the static calibration at a constant temperature; in the force/heat coupling experiments, at a heating rate of 0.4 ℃/s to 110 ℃ with a loading force of 500 N, the maximal output deviation is less than 1.06% (FS), realizing the unidirectional thermal force compensation of the structure. The double-sensor thermal compensation dynamometer can be utilized in sharp temperature fluctuations environment, like rocket engine forces measurement.

Effect of Constant Temperature Treatments Followed by Fluctuating Temperatures on the Softening of Hard Seeds of Trifolium subterraneum L

1981 ◽  
Vol 8 (6) ◽  
pp. 547 ◽  
Author(s):  
GB Taylor
Keyword(s):  
Constant Temperature ◽  
Early Period ◽  
Trifolium Subterraneum ◽  
Degradation Process ◽  
Temperature Treatment ◽  
Temperature Dependent ◽  
Thermal Degradation Process ◽  
Softening Process ◽  
Distinct Temperature ◽  
Fluctuating Temperatures

Three experiments are described in which the effects of constant temperatures ranging from 15 to 80°C, followed by diurnally fluctuating temperatures of 60/15°C were compared on seed softening in three cultivars of T. subterraneum. Constant temperature treatments alone produced relatively few soft seeds, but rapid seed softening ensued within a few days of subsequent fluctuating temperature treatment. The higher and the longer the constant temperature pretreatment, the more soft seeds were obtained. The rate at which this preconditioning of the seed took place was highest in the early stages of exposure to constant temperatures. Differences between cultivars and between temperature treatments were established mainly during this early period of constant temperature treatment. Rates of change of temperature in the 60/15°C fluctuation treatment were important in the final seed softening process: the slower the rate of temperature change the more soft seeds were produced. It is suggested that two distinct temperature dependent processes are involved in seed softening. The first appears to be a thermal degradation process which probably results in weakening of the strophiolar region. Fluctuating temperatures bring about the second stage of softening in which the strophiole is rendered permeable to water.

Persistent, vertical-migration rhythms in benthic microflora.: II. Field and Laboratory Studies On Diatoms From The Banks Of The River Avon

1966 ◽  
Vol 46 (1) ◽  
pp. 191-214 ◽  
Author(s):  
F. E. Round ◽  
J. D. Palmer
Keyword(s):  
High Temperatures ◽  
Vertical Migration ◽  
Laboratory Experiments ◽  
Biological Clock ◽  
Diatom Species ◽  
Laboratory Studies ◽  
Natural Conditions ◽  
Constant Illumination ◽  
Different Temperatures ◽  
Clock Hypothesis

The vertical migration of two Euglena species and several diatom species into and out of the sediment on the banks of the River Avon has been studied under natural conditions. All species have been shown to migrate vertically upwards when exposed during daylight. Tidal flooding of the sediment is generally preceded by re-burrowing of the algae beneath the surface. Methods have been devised to follow these migrations in both the field and laboratory. Laboratory experiments show that these migrations are rhythmic, continuing under constant illumination and temperature and removed from tidal influence. The effect of three different temperatures and three different light intensities has been investigated. Transfer from low to high temperatures has been shown to reset the phase of the rhythm. The results are discussed in relation to other work and to the ‘biological clock’ hypothesis.

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