冀西北农牧交错区草地螟寄生蜂及其控害作用

【目的】寄生蜂是草地螟Loxostege sticticalis L.卵期和幼虫期的重要天敌,但冀西北地区的发生种类、控害作用尚不明确。【方法】通过1997年以来历年田间调查,结合多年室内饲养。【结果】明确了当地草地螟寄生蜂共14种,其中卵期1种,幼虫期13种,1~5龄幼虫各龄期均有不同种寄生蜂寄生,寄生蜂种类多,种群数量大,寄生率高,控害和压低草地螟种群作用显著。【结论】该调查研究为开展草地螟预测预报,保护利用天敌资源和综合治理提供了科学依据。     

山东省亚洲玉米螟越冬特性及越冬代成虫发生期预测

【目的】亚洲玉米螟Ostrinia furnacalis(Guenée)是我国玉米生产上的重要害虫。亚洲玉米螟越冬特性及预测预报的研究,对于提高防治效果具有重要意义。【方法】本文通过对山东省东昌府、曲阜、商河、滨城区、即墨和栖霞地区玉米秸秆和穗轴进行剖查,统计越冬幼虫虫量和位置分布。并将幼虫带回济南放于室外待其化蛹,统计化蛹时间及存活率。【结果】山东省6个地区2007年春季玉米秸秆和穗轴中亚洲玉米螟平均越冬虫量分别为41.80头/百秆和19.91头/百穗,其中在玉米秸秆中越冬虫量占总量的67.30%。越冬幼虫在玉米秸秆上、中和下部比例分别为21.18%、38.80%和40.02%。越冬代亚洲玉米螟化蛹始盛期、高峰期、盛末期分别为5月27日、6月5日和6月21日,预测越冬代羽化始盛期、高峰期和盛末期分别为6月8日、6月17日和7月1日。【结论】应重视对亚洲玉米螟越冬虫源的控制,及时处理玉米秸秆和穗轴,第一代幼虫应该在6月中下旬防治,第二代应该在7月中旬防治。     

冷藏对美洲斑潜蝇蛹期发育和生存的影响

【目的】美洲斑潜蝇Liriomyza sativae Blanchard自20世纪90年代入侵我国后已经成为蔬菜和观赏植物的重要害虫。然而,近些年该昆虫已经逐渐成为研究植物和昆虫、昆虫抗寒性和寄主适应性等热点课题的模式种类。因此,为了实验室条件下更好保藏该虫的种群,本文研究了冷藏(世代发育起点温度8℃)对该斑潜蝇蛹发育和生存的影响。【方法】以化蛹后第3天的蛹为实验对象,8℃低温冷藏,并以冷藏时间(0、7、14、21、28和35 d)为参试因子研究了冷藏时间对美洲斑潜蝇蛹羽化率的影响;化蛹后每24 h解剖观察一次蛹并对蛹期发育阶段进行划分;根据划分的蛹期阶段,对处理中未羽化的蛹进行解剖比对,得到对低温最敏感的蛹期。【结果】随着冷藏时间的增长,美洲斑潜蝇的蛹羽化率逐渐降低。超过14 d后,羽化率明显下降。冷藏至35 d时羽化率为零。解剖正常发育的美洲斑潜蝇的蛹,将蛹期分为预蛹期、隐头蛹期、显头蛹初期、半透明眼期、浅黄色到琥珀色眼期、红褐色眼期、鬃毛蛹期。不同冷藏时间条件下,未羽化的蛹死亡时间主要为鬃毛蛹期,且鬃毛蛹期死亡的蛹的数量与贮藏时间呈正比例关系。【结论】在室内冷藏美洲斑潜蝇时,3日龄蛹8℃贮藏少于14 d为宜;鬃毛蛹期(10~11日龄蛹)对低温比较敏感,冷藏过程中,应避免鬃毛蛹期的蛹。     

THE INFLUENCE OF A 21 kDa KUNITZ‐TYPE TRYPSIN INHIBITOR FROM NONHOST MADRAS THORN,Pithecellobium dulce,SEEDS ON H. armigera (HÜBNER) (LEPIDOPTERA: NOCTUIDAE)

A trypsin inhibitor purified from the seeds of the Manila tamarind, Pithecellobium dulce (PDTI), was studied for its effects on growth parameters and developmental stages of  Helicoverpa armigera. PDTI exhibited inhibitory activity against bovine trypsin (～86%; ～1.33 ug/ml IC₅₀). The inhibitory activity of PDTI was unaltered over a wide range of temperature, pH, and in the presence of dithiothreitol. Larval midgut proteases were unable to digest PDTI for up to 12 h of incubation. Dixon and Lineweaver–Burk double reciprocal plots analysis revealed a competitive inhibition mechanism and a K_i of ～3.9 × 10^?8 M. Lethal dose (0.50% w/w) and dosage for weight reduction by 50% (0.25% w/w) were determined. PDTI showed a dose‐dependent effect on mean larval weight and a series of nutritional disturbances. In artificial diet at 0.25% w/w PDTI, the efficiency of conversion of ingested food, of digested food, relative growth rate, and growth index declined, whereas approximate digestibility, relative consumption rate, metabolic cost, consumption index, and total developmental period were increased in larvae. This is the first report of antifeedant and antimetabolic activities of PDTI on midgut proteases of  H. armigera.     

High cycling cadence reduces carbohydrate oxidation at given low intensity metabolic rate

Cycling cadence (RPM)-related differences in blood lactate concentration (BLC) increase with increasing exercise intensity, whilst corresponding divergences in oxygen uptake (V.O₂) and carbon dioxide production (V.CO₂) decrease. Aim of the present study was to test whether a higher RPM reduces the fraction (%) of the V.O₂ used for carbohydrate oxidation (relCHO) at a given BLC. Eight males (23.9 ± 1.6 yrs; 177 ± 3 cm; 70.3 ± 3.4 kg) performed incremental load tests at 50 and 100 RPM. BLC, V.O₂ and V.CO₂ were measured. At respiratory exchange ratios (RER) < 1, relCHO were calculated and the constant determining 50 % relCHO (k_CHO) was approximated as a function of the BLC. At submaximal workload V.O₂, V.CO₂, and relCHO were lower (all p < 0.002; η² > 0.209) at 50 than at 100 RPM. No differences were observed in V.O₂peak (3.96 ± 0.22 vs. 4.00 ± 0.25 l · min⁻¹) and RER_peak (1.18 ± 0.02 vs. 1.15 ± 0.02). BLC was lower (p < 0.001; η² = 0.680) at 50 than at 100 RPM irrespective of cycling intensity. At 50 RPM, kCHO (4.2 ± 1.4 (mmol · l⁻¹)³) was lower (p = 0.043; η² = 0.466) than at 100 RPM (5.9 ± 1.9 (mmol · l⁻¹)³). This difference in k_CHO reflects a reduced CHO oxidation at a given BLC at 100 than at 50 RPM. At a low exercise intensity, a higher cycling cadence can substantially reduce the reliance on CHO at a given metabolic rate and/or BLC.     

Quantitative delineation of how breathing motions open ligand migration channels in myoglobin and its mutants

Ligand migration and binding are central to the biological functions of many proteins such as myoglobin (Mb) and it is widely thought that protein breathing motions open up ligand channels dynamically. However, how a protein exerts its control over the opening and closing of these channels through its intrinsic dynamics is not fully understood. Specifically, a quantitative delineation of the breathing motions that are needed to open ligand channels is lacking. In this work, we present and apply a novel normal mode‐based method to quantitatively delineate what and how breathing motions open ligand migration channels in Mb and its mutants. The motivation behind this work springs from the observation that normal mode motions are closely linked to the breathing motions that are thought to open ligand migration channels. In addition, the method provides a direct and detailed depiction of the motions of each and every residue that lines a channel and can identify key residues that play a dominating role in regulating the channel. The all‐atom model and the full force‐field employed in the method provide a realistic energetics on the work cost required to open a channel, and as a result, the method can be used to efficiently study the effects of mutations on ligand migration channels and on ligand entry rates. Our results on Mb and its mutants are in excellent agreement with MD simulation results and experimentally determined ligand entry rates. Proteins 2015; 83:757–770. © 2015 Wiley Periodicals, Inc.     

Long-term effects of graduated compression stockings on cardiorespiratory performance

The use of graduated compression stockings (GCS) in sport has been increasing in the last years due to their potential positive effects for athletes. However, there is little evidence to support whether these types of garments actually improve cardiorespiratory performance. The aim of this study was to examine the cardiorespiratory responses of GCS during running after three weeks of regular use. Twenty recreational runners performed three tests on different days: test 1) – a 5-min maximal effort run in order to determine the participants’ maximal aerobic speed; and tests 2) and 3) – a fatigue running test of 30 minutes at 80% of their maximal aerobic speed with either GCS or PLACEBO stockings at random. Cardiorespiratory parameters (minute ventilation, heart rate, relative oxygen consumption, relative carbon dioxide production, ventilatory equivalents for oxygen and carbon dioxide, and oxygen pulse) were measured. Before each test in the laboratory, the participants trained with the randomly assigned stockings (GCS or PLACEBO) for three weeks. No significant differences between GCS and PLACEBO were found in any of the cardiorespiratory parameters. In conclusion, the present study provides evidence that running with GCS for three weeks does not influence cardiorespiratory parameters in recreational runners.     

Protein–protein association rates captured in a single geometric parameter

Understanding factors that drive protein–protein association is of fundamental importance. We show that a single geometric parameter in crystal structures of protein–protein complexes, the angle between the electric dipole of one subunit and the partner‐generated electric field at the same subunit, linearly correlates with experimentally determined protein–protein association rates. Imprint of a dynamic kinetic process in a single static geometric parameter, associated with mutual electrostatic orientation of subunits in protein–protein complexes, is elegant and demonstrates the universality of electrostatic steering in attenuating protein–protein association rates. That the essence of a complex phenomenon could be captured by properties of the final crystal structure of the complex implies that the electrostatic orientations of protein subunits in crystal structures and the associated transition states are nearly identical. Further, the cosine of the angle, alone, is shown to be sufficient in predicting association rate constants, with accuracies comparable to currently available predictors that use more intricate methodologies. Our results offer mechanistic insights and could be useful in development of coarse‐grained models. Proteins 2015; 83:1557–1562. © 2015 Wiley Periodicals, Inc.     

Predation rate and numerical response of Aphidoletes aphidimyza feeding on different densities of Aphis craccivora

Predation rate and numerical response are basic to any investigation of predator–prey relationships and key components in the selection of predators for biological control. The density-dependent predation rate and numerical response of Aphidoletes aphidimyza (Rondani) (Diptera: Cecidomyiidae) to varying densities (5, 10, 20, 40, 60 and 80) of third-instar Aphis craccivora (Koch) (Hemiptera: Aphididae), were studied in laboratory conditions [23±1°C, 70 ± 5% relative humidity (RH), and a photoperiod of 16:8 h L:D. Predation rate data were analysed using the age-stage, two-sex consumption rate software. Net consumption rate (C₀) increased by increasing prey density. The lowest and highest net consumption rates were 20.75 and 190.8 prey nymphs at densities of 5 and 80 A. craccivora. The transformation rate from prey population to predator offspring (Q_p) increased by increasing prey density. The reproductive numerical response, in terms of eggs laid, increased curvilinearly with increasing prey density. Females laid 121.375 ± 4.301 eggs when exposed to the highest prey density (80) and 52.5 ± 1.544 eggs at lowest prey density (5). It can be concluded that different densities of A. craccivora influenced the reproductive performance of A. aphidimyza in terms of predation rate and numerical response.     

Model misspecification confounds the estimation of rates and exaggerates their time dependency

While welcoming the comment of Ho et al. ( 2015 ), we find little that undermines the strength of our criticism, and it would appear they have misunderstood our central argument. Here we respond with the purpose of reiterating that we are (i) generally critical of much of the evidence presented in support of the time‐dependent molecular rate (TDMR) hypothesis and (ii) specifically critical of estimates of μ derived from tip‐dated sequences that exaggerate the importance of purifying selection as an explanation for TDMR over extended timescales. In response to assertions put forward by Ho et al. ( 2015 ), we use panmictic coalescent simulations of temporal data to explore a fundamental assumption for tip‐dated tree shape and associated mutation rate estimates, and the appropriateness and utility of the date randomization test. The results reveal problems for the joint estimation of tree topology, effective population size and μ with tip‐dated sequences using beast . Given the simulations, beast consistently obtains incorrect topological tree structures that are consistent with the substantial overestimation of μ and underestimation of effective population size. Data generated from lower effective population sizes were less likely to fail the date randomization test yet still resulted in substantially upwardly biased estimates of rates, bringing previous estimates of μ from temporally sampled DNA sequences into question. We find that our general criticisms of both the hypothesis of time‐dependent molecular evolution and Bayesian methods to estimate μ from temporally sampled DNA sequences are further reinforced.