THE INFLUENCE OF TEMPERATURE AND DAYLENGTH ON SPOTTED WILT VIRUS DISEASE OF TOMATO

The responses of young tomato plants to infection with tomato spotted wilt virus were studied at constant temperatures. The plants were grown in nutrient solutions and given three daylength treatments.
The length of the incubation period was positively correlated with temperature and a regression equation for this relationship is given. The calculated temperature at which this period becomes infinite is 6.7°C. The temperature coefficient ( Q ₁₀) varied from 1.7 to 2.9.
Dry-weight determinations were made of stems, leaves and roots. In healthy plants the leaf/stem ratio generally fell with rise of temperature and the shoot/root ratio rose. Infection changed these ratios, which is interpreted as indicating that it interfered with supplies of carbohydrate to the growing regions.
Systemic symptoms are described for plants raised at 11.4°, 18.3°, 23.9°, and 29.4°C.
Changes in daylength did not affect the systemic symptoms or incubation period. With a 9 hr. day at 29.4°C., the virus content of sap was significantly lower than with 12 or 15 hr., and with a 12 hr. day was significantly higher than with a 15 hr. day.     

THE CHANGING NUMBERS OF APHIS FABAE SCOP., FLYING AT CROP LEVEL, IN RELATION TO CURRENT WEATHER AND TO THE POPULATION ON THE CROP

Aphis fabae Scop, flying over bean crops in the summer usually show a double peak of aerial density during the day; scarcely any flight occurs at night. The first peak is thought to be composed mainly of alatae moulted since the previous evening and the decline of the peak to their depletion as they fly away from the crop. The second peak is probably composed mainly of alatae moulted during the same day. Lack of flight at night is due partly to low temperature, partly to lack of alatae old enough to fly and probably also to low light intensity.
Contrary to expectation changes in aerial density from hour to hour are only very weakly correlated with weather factors, especially wind-speed. The total numbers in each of the two peaks do show a low but significant correlation with both wind-speed and temperature in one case, but even then only a relatively small amount of the variation in aerial numbers is associated with weather changes. Other factors, particularly rapid changes in the numbers of alatae on the crop caused by moulting, accumulation before flight and depletion by flight evidently obscure changes due simply to varying flight behaviour. Thus because of large populations on the crop, it is possible to have quite large numbers in the air even when the weather is relatively unfavourable for flight.
In addition to these observations, the relation between total numbers caught at different wind-speeds shows that most of the migration occurred in winds when the aphids could have had no control over the general direction of flight. The current view that most migration takes place only in calm weather can therefore no longer be held.     

WIND DIRECTION AND THE INFESTATION OF BEAN FIELDS BY APHIS FABAE SCOP.

Bean fields are often attacked by Aphis fabae very heavily along the edges: and on a field at Rothamsted in 1948 the sides facing the wind during the primary migration had more colonies than those in the lee of the crop (Johnson, 1950). Additional observations on the distribution of colonies were made on six bean fields at Sutton Bonington in 1950–2.
At Rothamsted in 1948 it was assumed that the more numerous colonies on the windward sides of the field followed a heavier deposition of primary migrants there, though the migrants themselves were not observed on the crop. In 1950–2 the locations of primary migrants, as well as of colonies, were recorded in three out of the six fields observed.     

THE ANALYSIS AND RECONSTRUCTION OF DIURNAL FLIGHT CURVES IN ALIENICOLAE OF APHIS FABAE SCOP.

Experiments, in which alate aphids were marked immediately after eclosion from the last nymphal instar and observed until they took flight, gave information which, together with the measured rate of moulting and a continuous record of temperature, has been used to construct theoretical daily curves for numbers flying from a bean crop. These curves have been matched against the observed curves for the same days.
The differences between curves so constructed for a period of 17 days and the observed curves for the same period are of the same order and kind as the differences between two measured curves in different sites at the same time.
The different types of daily flight curve can thus be accounted for in terms of the rate of production of alatae by moulting, the effect of temperature on the teneral ('drying out') period and the effect of low light intensity and temperature on take-off behaviour.     

METHODS FOR MASS REARING AND INVESTIGATING THE HOST RELATIONS OF APHIS FABAE SCOP.

A method is described for producing some hundreds of apterous and thousands of alate virginoparous Aphis fabae every day continuously throughout the year. Broad beans are used as the host plants, in a 'production-line' arrangement of eleven ventilated breeding cages, with additional cages for starting subcultures and rearing alatae, all contained in a portion of a small greenhouse with supplementary lighting in winter. When running smoothly, the culture requires about half an hour's work by one man per day.
An 'aphid gun', being a modified type of aspirator catcher, is described, with which large numbers of aphids could be handled and counted rapidly without damaging them.
Amodified technique for host-transference experiments is described, which permits individual leaves to be compared one with another as host-units for the aphids. Two types of small metal cages are used, both easily attached to leaves in their natural positions on growing plants. One type confines the aphids to a part of a single leaf and is used mainly for determining relative reproduction rates on different leaves. The other type encloses equal areas of two different leaves between which the aphids can move freely, and is used for determining their behavioural preferences. The principles underlying the use of such cages, the experimental procedures and the interpretation of the results obtained are discussed.     

THE PRODUCTION OF PARTHENOGENETIC MAMMALIAN EMBRYOS AND THEIR USE IN BIOLOGICAL RESEARCH

1. The eggs of many mammalian species show signs of early parthenogenetic development as they age after ovulation and oocytes may form transplantable terato-carcinomas. These cases of apparently spontaneous parthenogenetic development suggest that the cells of the female germ line have an inherent tendency to divide and differentiate. 2. The ovulated eggs of virgin female mammals may be stimulated to start parthenogenetic development by a wide variety of treatments. Most of these damage the egg so that it does not develop beyond the 4 cell stage. However if the eggs are exposed to electrical activation, hyaluronidase treatment, or temperature shock then in many cases they will develop into blastocysts. 3. These blastocysts may be either haploid or diploid. Haploid blastocysts may be formed either by the egg extruding the nucleus of the second polar body or by the egg dividing in half, so that the female pronucleus is in one cell and the nucleus of the second polar body is in another cell. Diploid blastocysts are formed by the retention of the nucleus of the second polar body within the egg. The way in which the egg develops may be controlled by altering the osmolarity of the culture medium, the age of the egg at the time of activation, or the strain of animal used. 4. The action of the sperm on the egg can be defined by comparing the events of normal fertilization and parthenogenetic activation. Both these stimuli cause the egg to expose binding sites for Concanavalin A to synthesize DNA and to divide. However, the release of cortical granules, which occurs after fertilization, does not appear to be induced by parthenogenetic activation, and it is significant that parthenogenones lack the sperm nucleus and mitochondria. 5. The majority of parthenogenones die soon after implantation. Death at this time occurs with parthenogenones obtained from the activated eggs of both inbred and outbred stocks. Death might be caused by recessive lethal mutations or by extra-genetic effects of the maternal chromosomes. 6. Parthenogenones contain endogenous A-type particles which shows that these bodies are inherited through the female germ line. 7. Parthenogenones may in the future provide both a method for chromosome mapping and a source of haploid cells. At present the use of mammalian parthenogenones in biological research is restricted by the heavy embryonic losses which occur around the time of implantation. This means that the role of the sperm, gene activity and virus expression must be studied during a very limited period. Part of the mortality before implantation is the consequence of the damage which the egg suffers during activation and it should be possible to reduce this loss by improving the techniques for activation. It may also be possible to increase the quantity of cells derived from haploid and diploid mammalian embryos by deriving teratocarcinomas from them.     

A COMPARISON OF HIGH AND LOW VOLUME SPRAYS FOR CONTROL OF THE BEAN APHID, APHIS FABAE SCOP. ON FIELD BEANS

Insecticides were sprayed in different amounts of water to control Aphis fabae Scop. attacking spring-sown field beans. The single application of each insecticide was timed to coincide with the end of aphid migration from the winter host to the crop. A tractor-mounted row-crop hydraulic sprayer was used.
In one experiment seven different insecticide sprays were compared at high volume (in 140 gal. of water per acre); the most effective were nicotine at 22.4 oz. of active constituent per acre, demeton at 5.6 oz. and demeton-methyl at 11.2 oz.
A further comparison was made of five insecticides for each of which a selected dose of active ingredient was applied in 60 gal. (medium volume) and in 10 gal. of water per acre (low volume). The amount of insecticide retained on the plant following the low-volume application was not less than that from the medium-volume spray; the efficiency of A. fabae control was not affected by the volume sprayed except with malathion which did better at the medium volume. The systemic insecticides demeton-methyl at 6 oz. of active constituents per acre, the related compound 4741 at 3 oz. and fluoroacetamide at 3 oz. stopped the aphid numbers from rising above a peak of eight per plant compared with 230 per plant for malathion (low volume) at 12 oz. 2400 per plant for lindane at 6 oz. and 3550 per plant for check treatments sprayed with wetter only. Grain yields ranged from around 4 cwt. per acre on check treatments to around 27 cwt. per acre on plots sprayed once with the systemic insecticides. There was a curvilinear relationship between grain yield and log number of A. fabae per plant.     

甜菜蚜(半翅目,蚜科)的种下分化——基于形态与分子数据

甜菜蚜Aphis,fabae scopoli是世界广布性害虫,主要为害甜菜、蚕豆、荞麦、玉米等农作物以及欧洲卫矛、金莲花等园林植物,该种包含6个亚种,即指名亚种A.fabae fabae Scopoli、刺菜亚种A.fabae cirsiiacanthoidis Scopoli、卫茅亚种A.fabae evonymi Fabricius、牛蒡亚种A.fabae mordvilkoi B(o)rner & Janich、茄亚种A.fabae solanella Theobald和蓟亚种A.fabae eryngii E.E.Blanchtard.由于各亚种形态特征十分相似,分类学上通常依据次生寄主植物来鉴定.至于这些亚种是否成立,不同的学者观点不同.为此,本研究选取了甜菜蚜4个亚种(卫矛哑种和蓟亚种除外),基于比较形态特征和分子遗传差异来确定这些亚种的分类地位.光学显微镜下观察并测量了10个常用的鉴别形态特征,判别分析结果表明牛蒡亚种和指名亚种具有较高的交叉重叠范围,而刺菜亚种和茄亚种部分个体互相重叠,部分个体相对独立,形态特征结果分析说明这些特征并不能对4个亚种进行有效区分.基于线粒体基因Cyt 6、用于DNA条形编码的COⅠ基因序列片段和它的5'端,对4个亚种34个个体的分子数据进行了分析,结果表明4个亚种的所有个体之间基于COⅠ和Cyt b序列的遗传距离范围均为0.0%～1.3%;基于遗传距离所构建的邻接树(NJ)明显聚为两支(支持率100%),两分支之间的遗传距离范围为1.1%～1.3%,各亚种内部的遗传距离范围为0.00～0.03%;结果表明甜菜蚜可能是一个止在分化的物种,基于DNA序列的分析并不支持4个亚种的划分.     

豆蚜有翅蚜产生的原因

本文研究拥挤、寄土质量、温度和蚜型等因子对大豆蚜(Ahis glyeines)有翅蚜产生的影响。结果表明：1.大豆蚜无翅胎生成好个体间的拥挤是有翅蚜产生的主要原因。在低密度下拥挤反应随密度增大而增强,但过度拥挤会导致反应的降低。无翅若好间的拥挤不能导致其本身发育为有翅胎生蚜。 2.寄主质量能改变无翅胎生成蚜对拥挤的反应。每笼2头经成熟叶片处理的无翅胎生成蚜后代中有姻蚜的比例高于幼嫩叶片和对照(无叶片)处理,且饥饿不能促进有翅蚜的产生。3.温度能影响有翅蚜的产生。较高的温度(30℃和25℃)较21℃对有翅胎生蚌的产生有较强的抑制作用。4.不同母蚜型产生有翊蚜的能力不同。有翅胎生蚜间的拥挤也能使其在后代中产生少量的有翊蚜,但对拥挤的敏感程度低于无翅胎生蚜。     

INFLUENCE OF ANAESTHETICS ON THE BALANCE BETWEEN PRODUCTION AND UTILIZATION OF ENERGY IN THE BRAIN

Abstract— The influence of general anaesthesia upon the metabolic state of the brain was evaluated from the tissue concentrations of ATP, ADP and AMP, and from the concentrations of glycolytic and citric acid cycle intermediates, in immobilized and artificially ventilated rats anaesthetized either with 70% N₂O, 1% halothane or 60 mg/kg of pentobarbitone. The results were compared to the results obtained on awake animals in fentanyl-analgesia. The adenylate energy charge was identical in all groups studied and there were no H⁺-independent changes in the phosphocreatine/creatine ratios. In pentobarbitone anaesthesia there was an accumulation of glucose 6-phosphate and a fall in fructose 1,6-diphosphate, indicating inhibition of phosphofructokinase. No significant changes in these metabolites were observed with halothane or nitrous oxide anaesthesia and the substrate patterns differed from that obtained with pentobarbitone.
The blood glucose concentrations were higher in the unanaesthetized, immobilized rats given fentanyl than in those anaesthetized. There was a direct relationship between the glucose concentrations in blood and in tissue. The glucose concentration ratios intracellular water to blood were higher in the anaesthetized than in the unanaesthetized animals, increasing with increasing depth of anaesthesia. The intracellular lactate concentrations were lowest in the groups given pentobarbitone and fentanyl citrate, and there was thus no direct relationship between lactate concentration and depth of anaesthesia.     

关养密度和成年雄鼠填充物的气味对黄毛鼠(Rattus rattoides)的发育和性成熟的影响(英文)

黄毛鼠（Ｒａｔｔｕｓ ｒａｔｔｉｄｅｓ）在群居（４只／笼）时体重及性器官,如睾丸和附睾的增长都受到了极大的抑制;血清中睾酮含量的迅速上升以及成熟精子在附睾的曲细精管中出现的时间也比单独关养的晚。成年雄鼠的笼填充物的气味能够诱导幼年雄鼠体重,睾丸的总量和长度以及血清中睾酮的含量的增加。     

环境因子对角倍蚜秋迁蚜生殖和雌性蚜发育的影响

研究了环境因子对角倍蚜Schlechtendalia chinensis (Bell) 秋迁蚜生殖和雌性蚜发育的影响。温、湿度单因子试验表明,秋迁蚜在26℃和80%RH条件下有最大生殖量;温、湿度对秋迁蚜生殖量的影响均符合开口向下的二次抛物线变化趋势,极端温、湿度会导致生殖量的下降。采用三元一次正交组合设计,研究了环境温度（X₁）、湿度（X₂）和光照强度（X₃）三因子不同水平组合对雌性蚜发育的影响,表明温度是影响发育历期的主要因子,其次是光照强度,最后是湿度。因此,适当高温、强光照条件可以加快雌性蚜发育;而适当高湿条件可以降低雌性蚜的发育速率而延长其发育历期。在人工培育角倍蚜生产中,创造有利于秋迁蚜生殖的温、湿度条件可以使秋迁蚜产下较多的越冬侨蚜;在适当降低温度、增加湿度的阴暗条件下贮留雌性蚜可以适当延长其发育,以使角倍蚜与盐肤木在物候上达到最佳吻合。