A general model for effects of temperature on ectotherm ontogenetic growth and development

The temperature size rule (TSR) is the tendency for ectotherms to develop faster but mature at smaller body sizes at higher temperatures. It can be explained by a simple model in which the rate of growth or biomass accumulation and the rate of development have different temperature dependence. The model accounts for both TSR and the less frequently observed reverse-TSR, predicts the fraction of energy allocated to maintenance and synthesis over the course of development, and also predicts that less total energy is expended when developing at warmer temperatures for TSR and vice versa for reverse-TSR. It has important implications for effects of climate change on ectothermic animals.     

Influence of pH, temperature, and urea molar flowrate on Arthrospira platensis fed-batch cultivation: a kinetic and thermodynamic approach

Arthrospira platensis was cultivated photoautotrophically at 6.0 klux light intensity in 5.0-L open tanks, using a mineral medium containing urea as nitrogen source. Fed-batch experiments were performed at constant flowrate. A central composite factorial design combined to response surface methodology (RSM) was utilized to determine the relationship between the selected response variables (cell concentration after 10 days, X(m), cell productivity, P(X), and nitrogen-to-cell conversion factor, Y(X/N)) and codified values of the independent variables (pH, temperature, T, and urea flowrate, K). By applying the quadratic regression analysis, the equations describing the behaviors of these responses as simultaneous functions of the selected independent variables were determined, and the conditions for X(m) and P(X) optimization were estimated (pH 9.5, T = 29 degrees C, and K = 0.551 mM/day). The experimental data obtained under these conditions (X(m) = 749 mg/L; P(X) = 69.9 mg/L.day) were very close to the estimated ones (X(m) = 721 mg/L; P(X) = 67.1 mg/L.day). Additional cultivations were carried out under the above best conditions of pH control and urea flowrate at variable temperature. Consistently with the results of RSM, the best growth temperature was 29 degrees C. The maximum specific growth rates at different temperatures were used to estimate the thermodynamic parameters of growth (DeltaH* = 59.3 kJ/mol; DeltaS* = -0.147 kJ/mol.K; DeltaG* = 103 kJ/mol) and its thermal inactivation (DeltaH(D) (o) = 72.0 kJ/mol; DeltaS(D) (o) = 0.144 kJ/mol.K; DeltaG(D) (o) = 29.1 kJ/mol).     

Influence of temperature and photoperiod on embryonic development in the dragonfly Sympetrum striolatum (Odonata: Libellulidae)

Temperature and photoperiod play major roles in insect ecology. Many insect species have fixed degree‐days for embryogenesis, with minimum and maximum temperature thresholds for egg and larval development and hatching. Often, photoperiodic changes trigger the transfer into the next life‐cycle stadium. However, it is not known whether this distinct pattern also exist in a species with a high level of phenotypic plasticity in life‐history traits. In the present study, eggs of the dragonfly Sympetrum striolatum Charpentier (Odonata: Libellulidae) are reared under different constant and fluctuating temperatures and photoperiodic conditions in several laboratory and field experiments. In general, and as expected, higher temperatures cause faster egg development. However, no general temperature or light‐days for eyespot development and hatching are found. The minimum temperature thresholds are distinguished for survival (2 °C), embryogenesis (6 °C) and larval hatching (above 6 °C). Low winter temperatures synchronize hatching. Above 36 °C, no eyespots are visible and no larvae hatch. In laboratory experiments, light is neither necessary for eyespot development, nor for hatching. By contrast to the laboratory experiments, the field experiment show that naturally changing temperature and photoperiod play a significant role in the seasonal regulation of embryonic development. The post‐eyespot development is more variable and influenced by temperature and photoperiod than the pre‐eyespot development. This developmental plasticity at the end of the embryogenesis might be a general pattern in the Libellulidae, helping them to cope with variation in environmental conditions.     

温度对产虫茶昆虫紫斑谷螟生长发育的影响

为探明温度对贵州主要产虫茶昆虫紫斑谷螟Pyralis farinalis (Linnaeus)生长发育的影响, 本研究以白茶Litsea coreana为寄主植物, 分别设置5个恒温（19, 22, 25, 28和31℃）条件, 研究温度对紫斑谷螟卵、 幼虫、 蛹和未成熟期平均发育历期、 发育速率和存活率的影响, 计算各虫态发育起点温度和有效积温。 结果表明： 温度对紫斑谷螟各虫态发育历期、 发育速率和存活率影响显著。 在19 ~ 31℃范围内, 各虫态的平均发育历期均随温度的升高而缩短, 卵期、 幼虫期、 蛹期及未成熟期均在31℃达到最小值, 分别为4.56±0.24, 43.33±1.50, 7.89±0.20和55.78±1.69 d。 紫斑谷螟各虫态发育速率与温度呈二次回归关系, 且极显著相关。 此外, 温度显著影响各虫态存活率, 卵的存活率在28℃时最高, 为93%; 幼虫和蛹的存活率则在25℃最高, 分别为88%和93%; 温度过高或过低均不利于其生长发育。 由直接最优法计算得到紫斑谷螟卵期、 幼虫期、 蛹期及未成熟期的发育起点温度分别为13.30, 15.48, 13.19和14.82℃, 有效积温依次为88.36, 679.51, 159.73和952.04日·度。 这些结果为紫斑谷螟的繁殖提供了基础参考数据, 对指导虫茶生产有实用参考价值。     

短时高温对桃小食心虫生长发育与繁殖的影响

【目的】桃小食心虫Carposina sasakii是我国北方落叶果树的重要害虫。本研究旨在探索短时高温对桃小食心虫生长发育和繁殖的影响。【方法】在室内23±1℃、 相对湿度80%±7%和15L∶9D条件下, 测定了桃小食心虫卵、 幼虫、 蛹、 成虫在经历35, 38和41℃高温处理1～4 h后各阶段的发育历期、 存活率和产卵量。【结果】 短时高温对卵的孵化率无明显影响; 经41℃处理后, 初蛀果幼虫(1日龄)的发育历期明显延长, 且存活率显著降低, 3日龄以上的幼虫受到的影响不明显; 11日龄蛹的羽化率在38℃和41℃处理中明显降低, 畸形率也显著升高; 经38℃和41℃处理的成虫存活率降低, 寿命缩短, 产卵量也减少。【结论】短时高温处理对桃小食心虫卵的影响较小, 而对成虫的影响较大。这些结果有助于深入了解该虫在高温季节种群数量变动机制。