Effects Of Constant Temperatures Research Articles

Effects of constant temperature and daily fluctuating temperature on the transovarial transmission and life cycle of Aedes albopictus infected with Zika virus.

Numerous studies on the mosquito life cycle and transmission efficacy were performed under constant temperatures. Mosquito in wild, however, is not exposed to constant temperature but is faced with temperature variation on a daily basis. In the present study, the mosquito life cycle and Zika virus transmission efficiency were conducted at daily fluctuating temperatures and constant temperatures. Aedes albopictus was infected with the Zika virus orally. The oviposition and survival of the infected mosquitoes and hatching rate, the growth cycle of larvae at each stage, and the infection rate (IR) of the progeny mosquitoes were performed at two constant temperatures (23°C and 31°C) and a daily temperature range (DTR, 23-31°C). It showed that the biological parameters of mosquitoes under DTR conditions were significantly different from that under constant temperatures. Mosquitoes in DTR survived longer, laid more eggs (mean number: 36.5 vs. 24.2), and had a higher hatching rate (72.3% vs. 46.5%) but a lower pupation rate (37.9% vs. 81.1%) and emergence rate (72.7% vs. 91.7%) than that in the high-temperature group (constant 31°C). When compared to the low-temperature group (constant 23°C), larvae mosquitoes in DTR developed faster (median days: 9 vs. 23.5) and adult mosquitoes carried higher Zika viral RNA load (median log10 RNA copies/μl: 5.28 vs. 3.86). However, the temperature or temperature pattern has no effect on transovarial transmission. Those results indicated that there are significant differences between mosquito development and reproductive cycles under fluctuating and constant temperature conditions, and fluctuating temperature is more favorable for mosquitos' survival and reproduction. The data would support mapping and predicting the distribution of Aedes mosquitoes in the future and establishing an early warning system for Zika virus epidemics.

Effect of Phosphate Anodizing on Adhesive Property of AZ91D Magnesium Alloy under Constant Temperature and Humidity

Effects of constant temperature and humidity testing on the adhesive properties of phosphate-anodized AZ91D magnesium alloy were evaluated to produce multiple materials for lightening the fabrication of these materials. Phosphate-anodized AZ91D magnesium alloy, after immersion in dilute nitric acid solution, maintained strong adhesive strength even after constant temperature and humidity testing. These findings suggest that the anodization film is bonded chemically to the adhesive by the dilute nitric acid solution treatment.

A roadmap for ladybird conservation and recovery.

Ladybirds (Coleoptera: Coccinellidae) provide services that are critical to food production, and they fulfill an ecological role as a food source for predators. The richness, abundance, and distribution of ladybirds, however, are compromised by many anthropogenic threats. Meanwhile, a lack of knowledge of the conservation status of most species and the factors driving their population dynamics hinders the development and implementation of conservation strategies for ladybirds. We conducted a review of the literature on the ecology, diversity, and conservation of ladybirds to identify their key ecological threats. Ladybird populations are most affected by climate factors, landscape composition, and biological invasions. We suggest mitigating actions for ladybird conservation and recovery. Short-term actions include citizen science programs and education, protective measures for habitat recovery and threatened species, prevention of the introduction of non-native species, and the maintenance and restoration of natural areas and landscape heterogeneity. Mid-term actions involve the analysis of data from monitoring programs and insect collections to disentangle the effect of different threats to ladybird populations, understand habitat use by taxa on which there is limited knowledge, and quantify temporal trends of abundance, diversity, and biomass along a management-intensity gradient. Long-term actions include the development of a worldwide monitoring program based on standardized sampling to fill data gaps, increase explanatory power, streamline analyses, and facilitate global collaborations.

Mathematical Modelling of Infra-Red Evaporation Characteristics of Wheat Straw Black Liquor

Infrared (IR) evaporation characteristics of Weak Soda Black Liquor (WSBL) were determined at five different temperatures of 80, 90, 100, 110 and 120oC. The effect of constant temperature on evaporation rate and moisture content (on a dry basis) of 1.5 gm approx. WSBL tests were contemplated and required a careful time frame of IR dissipation to vanish the dampness content at a different consistent temperature. The dissipation rate expanded with expanding infrared temperature. Therefore, different numerical models, such as Page and Logarithmic, Henderson, Pabis and Lewis, were utilised to fit the experimental data properly. A Gaussian model equation was developed for evaporation rate and moisture fraction of black liquor. The probable empirical parameters, along with the relating of reduced chi-square (X2), Residual Sum of Square (RSS), and coefficients of determination (adjusted R2) from non-linear regression analysis of all the numerical model equations, were examined. In addition, the effect of evaporation temperature on the water removal rate, the effective diffusion coefficient and activation energy were also estimated. The effective diffusion coefficient ranges from 2.67 × 10–10 m2/s to 10.4 × 10–10 m2/s, and the activation energy was 39.19 kJ/mol. The statistical indicators (chi-square and determination coefficient) showed that the Decay model equation and Gaussian equation are the most suitable models for describing the evaporation process of WSBL.

Effect of Constant Temperatures on Biological Parameters of Tuta absoluta (Meyrick, 1917) on Tomato Plants in Case of Asexual Reproduction (Parthenogenesis

Tomato leafminer Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae) is a key devastating pest worldwide, it has the capacity to develop on a wide range of Solanaceous plants but tomato (Solanum lycopersicum L.) is considered to be its preferred host. This study was carried out at the Agricultural Scientific Research Centre in Latakia in 2019 to estimate biological parameters of T. absoluta and evaluate the effect of temperature in its development, longevity, reproduction in parthenogenesis. The experiments were carried out at constant temperatures (10, 20, 30˚ C), 60-65% RH, and photoperiod (16L: 8D). Biological parameters were analyzed according to the theory of age-stage two-sex life table by using the computer program TWO-SEX MSchart. The highest value of intrinsic rate of increase (r), the final increase rate (λ), and net reproductive rate (Ro) were 0.0439±0.0028 females/female/day, 1.0449±0.0029, and 7.01±0.8705 females/female/generation, respectively, at 20˚C. The lowest value of net reproductive rate (Ro) was 0.92±0.1250 females/female/generation at 30˚C. Generation time (T) was the longest (44.3±0.203 days) at 20˚C and decreased to 26.38±1.156 days at 30˚C. T. absoluta completed its development at all these temperatures. The results obtained showed that the effect of temperature on the insect development from egg to adult decreased with increased temperature. The shortest development period on egg, larva and pupa development was 3.95±0.149, 11.975±0.075 and 4.95±0.086 days, respectively, at 30˚C. This means that the development time from egg to adult was shorter (20.8±1.151 days) at 30˚C as compared to 34.51±0.127 days at 20˚C, and longest at 10˚C (125.4±1.211 days). The female longevity was longer (61.35±0.25 days) at 20˚C. The highest rate of fecundity was 12.98±1.072 eggs/unmated female, and the lowest was 2.19±0.152 eggs/unmated female at 30˚C. Moreover, the unmated females kept at 10˚C did not lay eggs, and unfertilized eggs (asexually produced eggs) laid by unmated females at 20 or 30˚C did not hatch. The adult pre-oviposition period (APOP) of unmated females was 2.57±0.1368 days at 20˚C and 4.31±0.2629 days at 30˚C, whereas the total APOP of females was 36.86±0.1844 days at 20˚C and 24.21±0.3039 days at 30˚C. Keywords: Tomato leaf miner, Life tables, asexual reproduction, Parthenogenesis, Syria

Exploration on key factors for overall migration into olive oil of food-contact silicone

To ensure the accuracy of the overall migration into olive oil of high risk food-contact silicone products, the key factors of the test method on the base of EN1186-1 &2 were analyzed and discussed. Two sample conditioning methods for the silicone products were compared, and the extraction times for olive oil in the samples were investigated, as well as the change trend of the actual temperature of olive oil at the set temperature. Using calcium chloride dryer conditioning method can achieve the same effect of constant temperature and humidity method, and can significantly reduce the conditioning time. For silicone products that are easily absorbed oil, the olive oil in the sample should be extracted at least twice. The temperature of the oven should be increased appropriately to meet the requirements of the temperature of olive oil. The water conditioning of samples, the extraction times of olive oil and the preheating temperature of olive oil are the key factors for olive oil overall migration of food-contact silicone, which can provide a reference for testing workers of food-contact materials.

Effects of thermal stress on the antioxidant defenses in Paracoccus marginatus Williams and Granara de Willink parasitized by Acerophagus papayae Noyes & Schauff

Acerophagus papayae (Encyrtidae: Hymenoptera) is a potential parasitoid successfully used to control papaya mealybug, Paracoccus marginatus (Homoptera: Pseudococcidae) on different horticultural crops such as papaya, mulberry, cotton, cassava, citrus, sweet potato, peas, beans, okra, eggplant, guava, Hibiscus Jatropha, Allamanda. However, the parasitic efficiency is mostly affected by prevailing weather parameter in the crop canopy. Understanding the effect of thermal stress on the parasitizing efficiency of natural enemy and the role of antioxidant mechanisms for temperature stress is important for improving efficiency under stressed condition. In this study, we investigated the effect of constant temperatures 25, 28, 30, 32 and 34oC on percent parasitism, developmental periods and adult emergence of A. papayae under laboratory condition. Increase in temperature negatively affected the performance of A. papayae in terms of developmental duration, parasitism efficiency and adult emergence. Exposure of A. papayae to different temperature led to overall increase in activities of superoxide dismutase, catalase, peroxidases and glutathione-S-transferases. Our results indicated that thermal tolerance in A. papayae could be mainly associated with changes in activity of antioxidant enzymes in scavenging of reactive oxygen species (ROS) under stress.

Effects of temperature on the development and fecundity of Microplitis similis (Hymenoptera: Braconidae), a parasitoid of Spodoptera litura (Lepidoptera: Noctuidae)

AbstractMicroplitis similis (Hymenoptera: Braconidae) is a solitary endoparasitoid of Spodoptera litura larvae (Lepidoptera: Noctuidae). Here, the effects of constant temperature (18, 21, 24, 27, 30, 33 and 36 °C) on the development and fecundity of M. similis developing in S. litura were studied in the laboratory to clarify the range of its potential distribution and better understand its potential as a biological control agent. The developmental duration of M. similis varied from 10.6 (33 °C) to 27.9 days (18 °C). The developmental threshold temperature and effective accumulative temperature of M. similis were 9.96 °C and 231.14 Degree‐days, respectively. The average adult longevity of M. similis ranged from 5.1 (33 °C) to 26.8 days (18 °C). The maximum fecundity of the parasitoid was observed at 27 and 30 °C, which were 43.07 and 39.73 eggs, respectively. The minimum fecundity of the parasitoid was observed at 18 °C, which was 8.27 eggs. The intrinsic rate of increase (rm) and finite rate of increase (λ) of M. similis were the highest at 30 °C. The net reproduction rate (R0) was the highest at 27 °C and 30 °C, which were 44.34 and 40.39, respectively. We concluded that temperatures in the range 27–30 °C are the most suitable for development and reproduction of M. similis. Our study provides detailed basic information for development and reproduction of M. similis under different temperature conditions.

The effect of temperature on the development of immature stages of <i>Aedes</i> spp. against breeding containers

Temperature is the main environmental factor affecting the growth of the mosquito population. It is important to study the effect of temperature on the life parameters of Aedes albopictus and Aedes aegypti in the local environment. This will subsequently provide an in-depth understanding on the biology of Aedes mosquitoes which will eventually affect the transmission of dengue viruses directly to human. This study examined the effect of constant temperatures on the developmental period of both local Aedes species strains using environmental chambers. Artificial and natural containers were used to examine the association of the types of containers to the development of both Aedes species. It was found that the increase in temperature may reduce the developmental period of the mosquito. In terms of the types of breeding containers, shortest development was recorded in the coconut shells, followed by tires, glass jars and plastic cups for both Aedes species. These findings provided valuable baseline information on the potential effects of climate change on the bionomics of Aedes mosquitoes and its density towards an improve vector control.

BIOLOGICAL ASPECTS OF THE TRUE SPIDER KOCHIURA AULICA (ARANEIDA: THERIDIIDAE) REARED ON THE FIRST LARVAL STAGE OF SPODOPTERA LITTORALIS IN EGYPT

Specimens of Kochiura aulica spider were collected from cotton crops in Qalyubia governorate during season 2017. Spiders were associated with the leaf cotton worm, Spodoptera littoralis(Boisduval, 1833) larvae. The spider Kochiura aulica (C.L. Koch, 1838) had 5 spiderlings for female and male. Individuals of the spider K. aulica were reared on the first larval stage of S. littoralis under laboratory conditions at three constant temperatures (20, 25 and 30°C and 60-70% R.H). The first spiderling recorded the longest duration compared to other spiderlings of female and male when fed on 1st larval stage of S. littoralis at three constant temperatures. Results indicate that individuals of K. aulica which were reared at 30 °C developed faster than those reared at 20 and 25 °C. The life cycle of K. aulica was the shortest when the spider reared at 30°C averaged 79.3 and 76.2 days followed by 25°C averaged 103 and 98.3 days and the longest values was 123.7 and 118.2 days at 20°C for female and male, respectively with significant differences among the three constant temperatures. Prey consumption was calculated for different stages. Effect of constant temperatures on longevity, life span and fecundity of the spider were studied. The number of consumed preys was the highest at 30 °C and the lowest at 20 °C. Also, the number of egg sacs per female was the highest at 30 °C and the lowest at 20 °C.

Effect of thermal boundary condition on forced convection from circular cylinders

Researchers commonly assume that the effect of constant temperature and constant heat flux thermal boundary condition on forced convection from a circular cylinder is negligible. Such claim was assessed using Computational Fluid Dynamics for Reynolds number, Re, ≤ 3,000. The flow was directly solved without modeling for Re ≤ 300, and Large Eddy Simulation was used for Re = 1,000 and Re = 3,000. Constant property simulations were done for Prandtl number of 0.7. Fluid dynamics parameters: drag coefficient, Strouhal number, separation angle and recirculation length, were used to assess the accuracy of the simulations. The main parameter of interest, the Nusselt number, is higher locally for constant heat flux than constant temperature for 60 ≤ Re ≤ 3,000. In addition, the ratio of overall Nusselt number for constant heat flux to that for constant temperature increases for Re < 30 and is ∼1.15 between 30 ≤ Re ≤ 3,000, showing that thermal boundary condition has significant effect on heat transfer from circular cylinder. Finally, the study developed empirical correlations relating overall Nusselt number to studied Reynolds number range.

Temperature stress interferes with male reproductive system development in clementine (Citrus clementina Hort. ex. Tan.)

AbstractMale gametophyte development is a critical phase of the plant life cycle due to its high sensitivity to environmental stresses. The rise in the average global temperature, often accompanied by extreme fluctuations, has an important impact on biological processes. Among those, male gametophytes are particularly sensitive to temperature stress during flower bud development and anthesis. Male gametophyte development was extensively studied in several plant species, but little information is available about the effects of temperature stress on male gametophyte development in the genus Citrus. We evaluated the effects of cold and hot temperatures during microsporogenesis and microgametogenesis on one of the most economically valuable citrus species, the “Comune” clementine (Citrus clementina Hort. ex. Tan.). The effect of constant temperature on the androecium was evaluated by a time course histological analysis performed on the anthers and by monitoring in vitro pollen germination. The results revealed how suboptimal hot and cold temperatures induce drastic alterations on the morphology of the tapetal cells, microspores and mature pollen grains. Shifting from the optimal temperature affected the timing of starch depletion in the anther walls, such as epidermis, endothecium and middle layer, influencing the pollen germination rate and pollen tube growth. To the best of our knowledge this is the first study attempting to assess how temperature stress affects male reproductive development in citrus. A better understanding of the mechanisms underlining male sterility will provide novel insights to elucidate the physiology of this agronomical important quality trait.

Effects of constant and stage-specific-alternating temperature on the survival, development and reproduction of the oriental armyworm, Mythimna separata (Walker) (Lepidoptera: Noctuidae)

Migratory insects make diverse adaptive strategies in response to changes in external environment. Temperature has an impact on the survival, development, reproduction, and migration initiation of insects. Previous research has primarily been focused on the effects of constant temperature on populations, but changing temperature has received less attention. Three constant temperature treatments (20, 25 and 30°C) and three pupal-alternating temperature treatments (20–25, 25–20 and 25–30°C) were set up to study the relationship between temperature and population development by age-stage, two-sex life table analysis in the oriental armyworm, Mythimna separata Walker, a notorious migratory pest in grain crops. The 25°C treatment was considered optimal with 20 and 30°C as low suitable temperature and high temperatures, respectively. The survival rate was relatively low before third instar larvae at 20°C (63.0%) and 20–25°C (70.1%), and extreme low after pupal stage at 30°C (20.6%). Developmental duration of each stage was negatively correlated with temperature. The adult pre-oviposition period, when most migratory insects initiate migration, was the shortest at 25°C (2.69 d) but was lengthened at both low suitable (7.48 d for 20°C, 6.91 d for 25–20°C and 4.57 d for 20–25°C) and high temperatures (3.74 d for 25–30°C and 5.00 d for 30°C). Both low suitable and high temperature decreased lifetime fecundity, net reproductive rate and the intrinsic rate of increase, with variability observed across developmental duration and stage during non-optimal temperature. The results expand knowledge of the relationship between changing temperature and armyworm population development, and adaptive strategies in complex ambient environment.

Germination temperatures and treatments to overcome dormancy in Belamcanda chinensis seeds1

ABSTRACT Belamcanda chinensis is an ornamental plant cultivated as a medicinal herb in its countries of origin: China and Japan. It is propagated by rhizomes and seeds, but little is known on the optimal conditions for its germination. This study aimed to assess germination temperatures and treatments to overcome its seed dormancy. Two experiments were conducted: the first evaluated the effects of constant temperatures of 20 ºC, 25 ºC and 30 ºC (in the dark) and 20-30 ºC with light (8-h photoperiod), while the second one involved the removal of combinations from the seed tegument structure (with and without tegument), with pre-hydration at 7 ºC, 30 ºC or no pre-hydration, in addition to an extra treatment without tegument or pre-hydration. Alternating the temperature results in better effects on the variables evaluated, while, at constant temperatures, there is little or no germination. The removal of the outer tegument structure and from seeds pre-hydrated at 30 ºC accelerates the germination process.

Impact of constant versus fluctuating temperatures on the development and life history parameters of Tetranychus urticae (Acari: Tetranychidae).

The impact of daily temperature fluctuations on arthropod life history parameters is inadequately studied compared with the ample amount of research that has been conducted on the effects of constant temperatures. Fluctuating temperatures are likely to be more realistic, as they are ecologically more similar to what these arthropods experience in nature. Here, we compared the impact of 11 constant temperatures that ranged from 10 to 35°C with fluctuating temperatures with the same corresponding mean temperature and an amplitude of 10°C between high (12h) and low (12h) temperatures on the development and life history parameters of Tetranychus urticae under continuous light conditions. No eggs hatched at constant 10°C, whereas 81.5% of eggs successfully completed development at fluctuating 10°C (15/5°C). Egg-to-female adult development was faster under fluctuating temperatures from 12.5 to 27.5°C than under constant temperatures, whereas the opposite trend was observed at >30°C. The lower thermal thresholds (T) were 11.63 and 8.63°C, and thermal constants (K) were 127.81 and 150.69 degree-days for egg-to-female adults at constant and fluctuating temperatures, respectively. The numbers of oviposition days were significantly higher at fluctuating 15°C than at the corresponding constant temperature, whereas the opposite trend was observed from 20 to 30°C. The intrinsic rate of increase (r) was higher at fluctuating than at constant 15°C. The net reproductive rate (R 0) was also higher at fluctuating than at constant 15 and 35°C, but showed an opposite trend at 20 and 25°C. We conclude that fluctuating temperatures should be considered to accurately predict spider mite population dynamics in nature.

Effects of temperature on the development, reproduction and population growth of Anaphothrips obscurus (Thysanoptera: Thripidae)

Anaphothrips obscurus is a cosmopolitan pest feeding on cereals and other grasses. The effects of constant temperatures on the biology of A. obscurus are not well known. Laboratory studies were conducted to assess the effects of temperature on the development, survival, longevity, fecundity and population parameter of A. obscurus at six constant temperatures (15, 20, 25, 30, 32, 35°C). The hatchability was the lowest at 15°C, the highest at 25°C and no eggs hatched at 35°C. Developmental rates increased linearly as the temperature increased. The lower developmental threshold temperature was 10.6°C and 200 degree-days were required to complete development from egg to adult. Adult longevity decreased with increasing temperature, and ranged from 68.87 d at 15°C to 16.41 d at 32°C. The highest total fecundity occurred at 20°C with 162 eggs per female. The temperature-dependent total fecundity, age-specific oviposition rate, and age-specific survival rate models were described. The intrinsic rate of increase (rm) was significantly higher at 30 and 32°C (0.239 and 0.250) than at other temperatures. This study suggests that optimal developmental and reproductive temperatures for A. obscurus ranges between 25 and 30°C and this may help this species adapt to warmer areas and widen its distribution and potential for damage in response to global warming. These findings will also be useful in developing monitoring programs, population dynamic models, and timing of control measures for A. obscurus.

Effect of different constant and alternative temperatures and light situations on germination behavior of two Purslane (Protulaca oleracea L.) populations

This study was carried out to investigate the germination behavior of two purslane populations (Karaj and Ahvaz), the effect of constant temperatures under two light regimes (12 hrs light/dark and continuous dark), alternative temperatures (day/night) and the lighting/darkness periods on purslane germination. The study was conducted in a randomized complete blocks design with four replications. The results showed that the highest percentage and germination rate in constant temperatures under two light regimes in Karaj mass (continuous darkness) and Ahvaz (12/12 hrs light/darkness), respectively at 25 and 30 °C (Optimum temperature) was observed. Purslane percentage and germination rate changes in alternating temperature (day/night) showed, the maximum values of both masses achieved at 30/20°C alternative temperature. According to result, by getting away from the optimum temperature, the germination percentage and its rate tends to have a descending process in both thermal experiments (alternative and constant temperature tests). Also the effect of different darkness/light periods on purslane percentage and germination rate showed, at (0/24) constant darkness treatment these traits got to the lowest point. The highest percentage and germination rates in Karaj and Ahvaz populations, respectively observed at 0/24, 12/12, 10/14 and 8/16 treatments; which had no statistical difference. Radicle length, shoot length and fresh weight of seedlings in both populations at constant temperatures under both light regimes at 20 to 30 °C and alternative temperatures (light/dark) at 30/20 °C had the highest values.International Journal of Natural Sciences (2014), 4(2) 13-21

Diurnal temperature variations affect development of a herbivorous arthropod pest and its predators.

The impact of daily temperature variations on arthropod life history remains woefully understudied compared to the large body of research that has been carried out on the effects of constant temperatures. However, diurnal varying temperature regimes more commonly represent the environment in which most organisms thrive. Such varying temperature regimes have been demonstrated to substantially affect development and reproduction of ectothermic organisms, generally in accordance with Jensen’s inequality. In the present study we evaluated the impact of temperature alternations at 4 amplitudes (DTR0, +5, +10 and +15°C) on the developmental rate of the predatory mites Phytoseiulus persimilis Athias-Henriot and Neoseiulus californicus McGregor (Acari: Phytoseiidae) and their natural prey, the two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae). We have modelled their developmental rates as a function of temperature using both linear and nonlinear models. Diurnally alternating temperatures resulted in a faster development in the lower temperature range as compared to their corresponding mean constant temperatures, whereas the opposite was observed in the higher temperature range. Our results indicate that Jensen’s inequality does not suffice to fully explain the differences in developmental rates at constant and alternating temperatures, suggesting additional physiological responses play a role. It is concluded that diurnal temperature range should not be ignored and should be incorporated in predictive models on the phenology of arthropod pests and their natural enemies and their performance in biological control programmes.

Temperature-dependent development of Lista haraldusalis (Walker) (Lepidoptera: Pyralidae) on Platycarya strobilacea

The effect of constant temperatures on development and survival of Lista haraldusalis (Walker) (Lepidoptera: Pyralidae), a newly reported insect species used to produce insect tea in Guizhou province (China), was studied in laboratory conditions at seven temperatures (19°C, 22°C, 25°C, 28°C, 31°C, 34°C, and 37°C) on Platycarya strobilacea. Increasing the temperature from 19°C to 31°C led to a significant decrease in the developmental time from egg to adult emergence, and then the total developmental time increased at 34°C. Egg incubation was the stage where L. haraldusalis experienced the highest mortality at all temperatures. The survival of L. haraldusalis was significantly higher at 25°C and 28°C, whereas none of the eggs hatched at 37°C. Common and Ikemoto linear models were used to describe the relationship between the temperature and the developmental rate for each immature stage of L. haraldusalis. The estimated values of the lower temperature threshold and thermal constant of the total immature stages using Common and Ikemoto linear models were 11.34°C and 11.20°C, and 939.85 and 950.41 degree-days, respectively. Seven nonlinear models were used to fit the experimental data to estimate the developmental rate of L. haraldusalis. Based on the biological significance for model evaluation, Ikemoto linear, Logan-6, and SSI were the best models that fitted each immature stage of L. haraldusalis and they were used to estimate the temperature thresholds. These thermal requirements and temperature thresholds are crucial for facilitating the development of factory-based mass rearing of L. haraldusalis.

Daily temperature fluctuations unpredictably influence developmental rate and morphology at a critical early larval stage in a frog

BackgroundEnvironmental temperature has profound consequences for early amphibian development and many field and laboratory studies have examined this. Most laboratory studies that have characterized the influence of temperature on development in amphibians have failed to incorporate the realities of diel temperature fluctuations (DTF), which can be considerable for pond-breeding amphibians.ResultsWe evaluated the effects of different ecologically relevant ranges of DTF compared with effects of constant temperatures on development of embryos and larvae of the Korean fire-bellied toad (Bombina orientalis). We constructed thermal reaction norms for developmental stage, snout- vent length, and tail length by fitting a Gompertz-Gaussian function to measurements taken from embryos after 66 hours of development in 12 different constant temperature environments between 14°C and 36°C. We used these reaction norms as null models to test the hypothesis that developmental effects of DTF are more than the sum of average constant temperature effects over the distribution of temperatures experienced. We predicted from these models that growth and differentiation would be positively correlated with average temperature at low levels of DTF but not at higher levels of DTF. We tested our prediction in the laboratory by rearing B. orientalis embryos at three average temperatures (20°C, 24°C, and 28°C) and four levels of thermal variation (0°C, 6°C, 13°C, and 20°C). Several of the observed responses to DTF were significantly different from both predictions of the model and from responses in constant temperature treatments at the same average temperatures. At an average temperature of 24°C, only the highest level of DTF affected differentiation and growth rates, but at both cooler and warmer average temperatures, moderate DTF was enough to slow developmental and tail growth rates.ConclusionsThese results demonstrate that both the magnitude of DTF range and thermal averages need to be considered simultaneously when parsing the effects of changing thermal environments on complex developmental responses, particularly when they have potential functional and adaptive significance.