Use of a novel two-stage cultivation method to determine the effects of environmental factors on the growth and sporulation of several biocontrol fungi

To supply essential information for improving mass production and biocontrol efficacy, two-stage cultivation on agar plates was used to evaluate the environmental conditions affecting mycelial growth and sporulation of seven biocontrol fungi. Maximum growth and sporulation occurred on acid media for Paecilomyces (Pa.) lilacinus IPC-P, Pochonia (Po.) chlamydosporia HSY-12-14, and Lecanicillium lecanii CA-1-G, and on alkaline media for Metarhizium anisopliae isolates. All fungi preferred a certain water potential and temperature for sporulation. Light greatly inhibited the growth of P. lilacinus IPC-P, M. anisopliae SQZ-1-21, and L. lecanii CA-1-G but enhanced the sporulation of P. lilacinus M-14, P. chlamydosporia HSY-12-14, and L. lecanii CA-1-G.     

Response of <Emphasis Type="Italic">Sphagnum</Emphasis> species mixtures to increased temperature and nitrogen availability

To predict the role of ombrotrophic bogs as carbon sinks in the future, it is crucial to understand how Sphagnum vegetation in bogs will respond to global change. We performed a greenhouse experiment to study the effects of two temperature treatments (17.5 and 21.7°C) and two N addition treatments (0 and 4 g N m⁻² year⁻¹) on the growth of four Sphagnum species from three geographically interspersed regions: S. fuscum, S. balticum (northern and central Sweden), S. magellanicum and S. cuspidatum (southern Sweden). We studied the growth and cover change in four combinations of these Sphagnum species during two growing seasons. Sphagnum height increment and production were affected negatively by high temperature and high N addition. However, the northern species were more affected by temperature, while the southern species were more affected by N addition. High temperature depressed the cover of the ‘wet’ species, S. balticum and S. cuspidatum. Nitrogen concentrations increased with high N addition. N:P and N:K ratios indicated P-limited growth in all treatments and co-limitation of P and K in the high N treatments. In the second year of the experiment, several containers suffered from a severe fungal infection, particularly affecting the ‘wet’ species and the high N treatment. Our findings suggest that global change can have negative consequences for the production of Sphagnum species in bogs, with important implications for the carbon sequestration in these ecosystems.     

Effects of temperature on the development and reproduction of sugarcane top borer Scirpophaga excerptalis (Lepidoptera: Pyralidae)

To determine the effects of temperature on the development and reproduction of top borer Scirpophaga excerptalis Walker (Lepidoptera: Pyralidae), the durations of different developmental stages and reproductive capacity of S. excerptalis were measured at 20, 23, 26, 29 and 32℃. The results showed that the average durations of various developmental stages of S. excerptalis shortened with increasing temperatures from 20 to 32℃. The durations to complete one life cycle were 113.17 days at 20℃, and 39.50 days at 32℃. The developmental rate of each stage and generation was positively correlated with the temperature, which was consistent with the Logistic regression model. The temperature thresholds for egg, larval, pupal and preoviposition stages and the total cycle were 13.73, 14.73, 13.91, 13.66 and 14.10℃, respectively. The effective accumulative temperature was 112.62, 370.01, 188.17, 23.82 and 718.07 degree-days (DD), respectively. The adult longevity shortened with increasing temperatures, and the highest number of eggs laid per female was 204.74 eggs at 29℃. The survival rates of eggs, larvae and the whole generation were the highest at 26℃, which were 87.25%, 56.67% and 37.21%, respectively while the highest survival rate of the pupa was 76.69% at 29℃. There was no significant difference for the total cycle at 23-29℃. The results indicated that temperature was the key factor affecting the development and reproduction of S. excerptalis, and the optimum temperature for development and reproduction ranged from 23 to 29℃.     

温度对鲫鱼性腺分化的影响

鱼类的性腺分化受各种环境因素的影响,而温度的影响是重要因素之一.本文通过组织学方法观察了鲫鱼(Carassius auratus)原生殖细胞的迁移、生殖嵴形成和性腺分化,并探讨温度对性腺分化的影响.孵化后12～40 d是鲫鱼性腺分化的敏感期.从第12 d起,仔鱼分成7组,每组分别用下列7种水温中的一种培育28 d:(16±1)℃、(20±1)℃、23～25℃、(27±1)℃、(30±1)℃、(32±1)℃、(34±1)℃.其中23～25℃组是对照组.结果显示,对照组幼鱼的雌雄比例大致是1:1(1:1.07).(20±1)℃组的幼鱼雌雄比例也接近1:1(1.09:1).在(27±1)℃组,雌性率上升,为55.3%(P<0.05).在低温组(16±1)℃,雌雄比例是1:1.45,雌性率达40.8%.然而,在高温组(30±1)℃、(32±1)℃、(34±1)℃中,雌雄比例分别是6.14:1、2.51:1和2.14:1.其中(30±1)℃实验组的雌性率最高,达到86.0%(P<0.01),性腺分化趋向雌性化.研究提示,鲫鱼的性别分化属于温度依赖型.当前全球性气候变暖,以及各种环境因素所产生的温室效应,有可能对鲫鱼的性别平衡产生影响.     

青阳参种子的萌发

青阳参（Cynanchum otophyllum）种子在11月成熟时有休眠习性。收获后将其种子种植在自然温室内,到第二年的春天种子才会萌发,且大多数种子在3月28至4月4日间萌发,这期间的日平均最高和最低温度分别为19．0℃和9．9℃。层积能有效地打破青阳参种子的休眠,休眠种子通过大约1周的层积便能萌发。种子在有光的条件下层积1周后转移到25／15℃的黑暗条件下萌发率可达到75．4％。青阳参种子不论在有光的条件下还是在黑暗环境中层积2～3周后转入30／20和25／15℃进行变温处理,其萌发率最低能达到66．4％,而转入20／10℃变温处理其萌发率最多只能达到20．1％,但若层积6周,即便在20／10℃变温处理的情况下其萌发率也可以达到65．3％以上。     

Quantifying the instability of core temperature in rodents

Radiotelemetry provides researchers with the ability to sample the core temperature of rodents and other species rapidly. Compared to large mammals, the time-course of core temperature of rodents is variable and their data are often averaged into bins of one or more hours for publication. When viewing averaged data, a stable core temperature over a wide range of ambient temperatures is observed; however, if the time-course of core temperature of individual animals is examined closely with a sampling period of 1–10 min, a continuous waxing and waning of temperature is observed. It is proposed that calculating the change in temperature from one time point to the next (i.e., temperature differential) is an informative measure of the performance of the thermoregulatory system. A quantitative measure of the stability of the thermoregulatory system can be determined by calculating the absolute value of the temperature differential. It is shown that the absolute temperature differential (ATD) is dependent on ambient temperature, genetic strain, type of cage bedding, and body size. The ATD is simple to calculate from telemetry data and may be an important parameter for the study of rodent thermal physiology.     

Cometabolic biodegradation of 4-chlorophenol by sequencing batch reactors at different temperatures

The simultaneous removal of 4-chlorophenol (4-CP) and phenol in lab-scale sequencing batch reactors at different temperatures has been studied. Phenol feed concentration was fixed at 525 mg/L and 4-CP concentration was increased from 105 to 2100 mg/L at a constant hydraulic residence time (HRT) of 10.5 d. Complete phenol and 4-CP biodegradation was achieved during the aerobic stage working with 4-CP concentrations up to 1470 mg/L in the feed. Both 4-CP and phenol specific initial removal rates were strongly affected by 4-CP feed concentration and temperature. Only at the highest temperature tested (35 °C) it was possible to increase the maximum assimilative 4-CP concentration by the biological sludge up to 2100 mg/L, and a significant reduction of the ecotoxicity of the effluents was observed. 4-chlorocatechol (4-CC) was identified as the major intermediate in the aerobic cometabolic 4-CP degradation, being the ecotoxicity of that species substantially lower than that of 4-CP.     

Photosynthetic capacity and temperature responses of photosynthesis of rubber trees (Hevea brasiliensis Müll. Arg.) acclimate to changes in ambient temperatures

The aim of this study was to assess the temperature response of photosynthesis in rubber trees (Hevea brasiliensis Müll. Arg.) to provide data for process-based growth modeling, and to test whether photosynthetic capacity and temperature response of photosynthesis acclimates to changes in ambient temperature. Net CO₂ assimilation rate (A) was measured in rubber saplings grown in a nursery or in growth chambers at 18 and 28°C. The temperature response of A was measured from 9 to 45°C and the data were fitted to an empirical model. Photosynthetic capacity (maximal carboxylation rate, V _cmax, and maximal light driven electron flux, J _max) of plants acclimated to 18 and 28°C were estimated by fitting a biochemical photosynthesis model to the CO₂ response curves (A–C _i curves) at six temperatures: 15, 22, 28, 32, 36 and 40°C. The optimal temperature for A (T _opt) was much lower in plants grown at 18°C compared to 28°C and nursery. Net CO₂ assimilation rate at optimal temperature (A _opt), V _cmax and J _max at a reference temperature of 25°C (V _cmax25 and J _max25) as well as activation energy of V _cmax and J _max (E _aV and E _aJ) decreased in individuals acclimated to 18°C. The optimal temperature for V _cmax and J _max could not be clearly defined from our response curves, as they always were above 36°C and not far from 40°C. The ratio J _max25/V _cmax25 was larger in plants acclimated to 18°C. Less nitrogen was present and photosynthetic nitrogen use efficiency (V _cmax25/N _a) was smaller in leaves acclimated to 18°C. These results indicate that rubber saplings acclimated their photosynthetic characteristics in response to growth temperature, and that higher temperatures resulted in an enhanced photosynthetic capacity in the leaves, as well as larger activation energy for photosynthesis.     

Elevated CO2 concentration and temperature effects on the partitioning of chemical components along juvenile Scots pine stems (Pinus sylvestris L.)

The effects of doubled ambient [CO₂] and different temperature levels on young Pinus sylvestris growing in phytotron chambers were studied. Five chambers were supplied with ~380 (‘ambient air’) and five with ~700 μmol mol⁻¹ CO₂ (‘elevated [CO₂]’). Temperature levels in the chambers ranged in increment steps of 2°C from −4°C to +4°C relative to the long-term monthly (day and night) average air temperature levels in Berlin–Dahlem. Substrate was medium fertile; soil moisture and air humidity were kept constant. After three vegetation periods twigs and stems were harvested, weighed, homogenized, and analyzed chemically. There was no significant temperature effect on wood mass accumulation, clearest positive [CO₂] effect occurred in the youngest twigs. In total, wood mass increased by 28.5% at doubled ambient [CO₂]. N-contents (percentage) decreased at elevated [CO₂] in the uppermost stem sections and not in twig wood causing wider C/N ratios in total. In response to elevated temperature, N-contents decreased slightly in twigs (~0.3%). Traces of free glucose, fructose and sucrose, which decreased from the top to the bottom, were found in stem wood, in contrast to traces of starch that increased from the top to the bottom. In response to elevated [CO₂] only a little more (0.05%) was accumulated in the top shoot and in tendency; glucose, fructose, and sucrose contents were lower at the bottom of stems as compared to the control. There was no obvious response of these non-structural carbohydrates to elevated temperature except for starch that decreased to half of the content from the lowest to the highest temperature level. Among the hemicellulose compounds, rhamnose and arabinose declined from the top shoot to the bottom of stem, whereas 4-O-methyl-d-glucuronic-acid, mannose, and xylose increased. Contents (percentage) of galactose remained approximately stable along the stem. The clearest positive effect of elevated [CO₂] along the whole stem was found for mannose with differences of 0.6–0.3%. In contrast to rhamnose and arabinose that showed a negative response to elevated [CO₂], mannose was reduced towards the uppermost stem sections. The 4-O-methyl-d-glucuronic-acid was slightly lowered at the bottom, and galactose and xylose showed no [CO₂] response. The only hemicellulose compound which reacted to temperature elevation was galactose. It increased slightly (~0.1% per 1°C). Cellulose and lignin (Klason) behaved oppositely: cellulose increased and lignin decreased from the top to the bottom. These structural components behaved reversely also in response to elevated [CO₂]. In stem parts above the bottom section, cellulose content was slightly higher at elevated [CO₂], and lignin content was slightly lower at the bottom. Lignin reacted to temperature elevation by a very slight increase on the average (~0.1% per one 1°C). Cellulose, however, decreased by ~0.2% per 1°C temperature elevation. The importance of persistent sinks of carbon in woody plant parts is discussed in respect to the greenhouse effect.     

The ecological impact of an introduced population on a native population in the firefly Luciola cruciata (Coleoptera: Lampyridae)

In Japan, Tatsuno Town has been famous for many Luciola cruciata fireflies emerging every summer at least since the 1920s. However, in the 1960s, L. cruciata fireflies were intentionally introduced from the Lake Biwa area into Matsuo-kyo, the most famous habitat of fireflies in that town. In this study, I examined ambient temperatures and flash rates of L. cruciata at four sites including Matsuo-kyo in the Tatsuno area and two sites in the Lake Biwa area. The linear regression of flash rates on temperatures indicated that the Matsuo-kyo population was distinct from the other three populations native to the Tatsuno area, but similar to the two populations native to the Lake Biwa area in terms of flash rates. These results were also supported by a recent molecular biological study, suggesting that the introduced fireflies had a strong ecological impact on the native ones at Matsuo-kyo. The present study emphasizes that we should not transport and release L. cruciata fireflies without careful consideration.