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.     

AGGREGATION IN APHIS FABAE SCOP. I. AGGREGATION ON PLANTS

A study of free infestations of Aphis fabae Scop. on the leaves of its host plants, spindle and sugar beet, showed that the clustered distribution of the aphids within the boundaries of each leaf was not a matter of chance but involved active aggregation. Experiments in small leaf cages showed that aggregation could take place independently of any differences between portions of a leaf, being brought about by truly gregarious reactions between the aphids. Experiments in which walking aphids were made to encounter other live or dummy aphids fixed to leaves, showed that the gregarious reactions were of at least two kinds. The aphids both probed more often, and remained inserted for longer, near other aphids than apart from them.
It appears that the unequal distribution of aphids among the leaves of a plant is due primarily to intrinsic differences between leaves, but is aided by gregariousness, while the aggregations observed on leaves are due primarily to gregariousness, and only secondarily to differences between portions of a leaf. It is suggested that the primary function of gregariousness is to concentrate the aphids on to the best feeding sites, both among the parts of a plant, and among whole plants; that is, it acts as an aid in host selection, even with aphids which do not aggregate so compactly as A. fabae. The functions of compact aggregation and other specialized forms of gregarious behaviour remain to be discovered.     

INFESTATION OF A BEAN FIELD BY APHIS FABAE SCOP. IN RELATION TO WIND DIRECTION

The wind direction during the primary migration of Aphis fabae Scop, gave a plausible explanation of the infestation pattern round the edge of a bean field; but it is emphasized that other factors are involved whose effects have not been adequately-assessed in this preliminary survey.     

HOST FINDING BY APHIDS IN THE FIELD: APHIS FABAE SCOP. (GYNOPARAE) AND BREVICORYNE BRASSICAE L.; WITH A RE-APPRAISAL OF THE ROLE OF HOST-FINDING BEHAVIOUR IN VIRUS SPREAD

Aphis fabae gynoparae occurred in the same large proportion in simultaneous collections of all aphids alighting and probing on, and taking off from, a host plant (spindle) and a non-host (peach), and behaved similarly when approaching and leaving them in the same conditions. Most alighters took off again from leaves of both kinds within a few minutes, staying longer and probing more times on the host. In atmospheric conditions favouring local 'hovering' instead of dispersal, flying and alighting aphids became concentrated around host plants, not through any specific attraction to them, but apparently because more aphids had accumulated upon them and were now taking off.
Brevicoryne brassicae occurred in the same large proportion in simultaneous collections of aphids alighting on a host plant (cabbage) and a non-host (sugar beet). No satisfactory evidence was found of preferential alightment on cabbage and there were indications of preferential alightment on the non-host. A very small minority of the A. fabae and B. brassicae that alighted on their hosts stayed there long enough to larviposit. This minority was rather larger among alighters late in the day, but in the absolute sense, more colonization occurred during earlier periods when more aphids arrived.
The intensely dispersive type of host-finding behaviour in Myzus persicae, A. fabae and B. brassicae may be common among Aphididae. It seems ideal for the dissemination of non-persistent plant viruses, more particularly among the less-favoured host plants of each aphid. The tendency to commensal association between virus and vector provides an ecological framework which may govern the incidence of virus-vector specificity and symbiosis.     

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.     

INFLUENCE OF DAYLENGTH ON THE PRODUCTION OF PARTHENOGENETIC AND SEXUAL FEMALES OF APHIS FABAE AT 17.5°

When apterous virginoparae of Aphis fabae and their progenies were raised at 17.5^o on leaf discs of Vicia faba under photoperiods of 12 h or less per day, more alatae occurred among the progenies than under longer photoperiods. The alatae developed exclusively into gynoparae at 4, 10 and 12 h light per day and almost all did so at 2 h. At 13 h 45 min, 14 h, 16 h, and 24 h all the alatae developed into virginoparae. At transitional photoperiods ranging from 13 h 6 min to 13 h 28 min, both alate morphs occurred. They could both be deposited by a single apterous virginopara and produce intermorphs containing eggs and embryos. Under most light regimes, a proportion of the gynoparae (generally < 10%) produced some apterous virginoparae, gynoparae, and males after producing a number of oviparae. Alate virginoparae produced almost three times as many larvae as did the gynoparae.By transferring alatiform larvae produced by apterae raised at short day (SD: 10 h light) to long day (LD: 16 h light) or vice versa, a strong prenatal influence of SD on gynopara production was demonstrated. SD also had a postnatal influence on presumptive virginoparous alatiforms, if they were transferred to SD already in the 1 st instar. Alatiform larvae could be influenced by SD or LD as late as in the 3d instar if they and their mothers had been maintained under a weak short (13 h 6 min) or a weak long day (13 h 45 min).The results are discussed in relation to possible hormonal mechanisms of morph determination.

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Zusammenfassung Wenn ungeflügelte, virginopare Aphis fabae und ihre Nachkommen gehalten wurden bei 17,5^o auf Blattscheiben von Vicia faba bei Fotoperioden von 12 oder weniger Stunden je Tag, so entstanden mehr Geflügelte unter den Nachkommen als unter längeren Fotoperioden. Die Geflügelten entwickelten sich ausschliesslich zu Gynoparen bei 4, 10 und 12 h Licht je Tag und fast alle bei 2 h. Bei 13 h 45 min, 14, 16 und 24 h entwickelten sich alle Geflügelten zu Virginoparen. Bei Übergangsfotoperioden zwischen 13 h 6 min und 13 h 28 min kamen beide geflügelte Morphen vor. Diese konnten beide von einer einzigen ungeflügelten Virginopara abgesetzt werden und Zwischenformen mit Eiern und Embryonen erzeugen. Bei den meisten Fotoperioden erzeugte ein Teil der Gynoparen (meist < 10%) einige ungeflügelte Virginopare, Gynopare und Männchen, nachdem sie eine Anzahl von Oviparen erzeugt hatten. Geflügelte Virginopare erzeugten fast dreimal so viele Larven als wie Gynopare es tun.Wenn man alatiforme Larven, deren ungeflügelte Mütter bei Kurztag (KT: 10 h Licht) gehalten waren, in Langtag (LT: 16 h Licht) übertrug oder umgekehrt, so zeigte sich ein starker pränataler Einfluss des KT auf die Gynoparenerzeugung. KT hatte auch einen postnatalen Einfluss auf präsumptive virginopare geflügelte Formen, wenn diese schon im 1. Larvenstadium übertragen wurden. Alatiforme Larven konnten selbst noch im 3. Stadium durch KT oder LT beeinflusst werden, wenn sie und ihre Mütter bei schwachem Kurz- (13 h 6 min) oder schwachem Lang- (13 h 45 min) Tag gehalten waren.Die Ergebnisse werden in Hinsicht auf mögliche hormonale Mechanismen der Morphenbestimmung diskutiert.

     

THE SPREAD OF BEET YELLOWS AND BEET MOSAIC VIRUSES IN THE SUGAR-BEET ROOT CROP I. FIELD OBSERVATIONS ON THE VIRUS DISEASES OF SUGAR BEET AND THEIR VECTORS MYZUS PERSICAE SULZ. AND APHIS FABAE KOCH

A survey of aphids and virus diseases of sugar-beet root crops in eastern England was made between 1940 and 1948. Prior to 1943 the observations were made on fertilizer experiments; from 1943 onwards they were made on commercial fields selected for position in relation to beet and mangold seed crops. The incidence of beet yellows increased with increasing numbers of Myzus persicae , but not of Aphis fabae. The relation with M. persicae was sufficiently close to suggest that it is the most important, possibly the only important, vector of beet yellows virus. Beet mosaic virus also increased with increasing numbers of M. persicae , but the relation was not close enough to exclude the possibility of other vectors.
Numbers of A. fabae on sugar beet were slightly, but consistently, depressed by the use of salt as a fertilizer. Other fertilizers had variable effects. Neither aphids nor virus are likely to be greatly affected by fertilizers.
Beet yellows is most prevalent in areas where seed crops are grown, but within these areas nearness to individual seed crops did not appear to increase its incidence. M. persicae were more numerous on sugar beet in seed-crop areas than elsewhere, and this alone might account for the prevalence of yellows. Beet mosaic virus is more closely associated with seed crops than is beet yellows. It is most prevalent near to seed crops within the seed-crop areas.     

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.     

ÜBER DIE URSACHEN DER UNTERSCHIEDLICHEN RESISTENZ VON VICIA FABA L. GEGENÜBER DER BOHNENBLATTLAUS,APHIS (DORALIS) FABAE SCOP

Zusammenfassung Fruchtbarkeit und Wachstum von vier auf Ackerbohnen (Vicia faba) lebenden Aphiden-Arten (Aphis fabae, A. craccivora, Acyrthosiphon pisum, Megoura viciae) werden von den Sorten Schlanstedter und Rastatter in gegensätzlicher Weise gefördert bzw. gehemmt. Post-infektionelle Resistenzeffekte treten daher einerseits bei Rastatter gegen A. fabae, andererseits aber bei Schlanstedter Ackerbohnen gegen Erbsen- und Wickenläuse auf, während sich A. craccivora auf beiden etwa gleich gut entwickelt.

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Summary Aphis fabae, Aphis craccivora, Acyrthosiphon pisum, and Megoura vicae (abbreviated Af, Ac, Ap and Mv, respectively) were allowed to develop under similar uncaged conditions on Rastatter (R) and Schlanstedter (S) field beans. Large, sometimes contradictory, differences in the fecundities and weights attained by adult apterous virginoparae on these plants were recoreded and ascribed to postinfestation resistance effects.Ap, which feed only on leaves, and Mv, which feed exclusively on internodes, weigh significantly more (17–18%) on R than on S. In contrast, Af, which feed on various plant parts, are 61% heavier on the leaves and 33% heavier on the stems of S than on the corresponding parts of R.However, Ac, which have a distribution on the plants similar to that of Af, are somewhat heavier (12%) on R-leaves and on S-stems than on the corresponding plant parts of the other variety. Such differences are greatly diminished if the aphids are reared on excised leaves and stems immersed in water. In this case growth of the aphids on excised parts of the resistant varieties (on which they previously grew poorly) closely approaches that on the intact satisfactory varieties (on which they grew well). Only small (Af, Ac) or no (Ap, Mv) improvement in growth results when the aphids are reared on excised parts of the satisfactory variety. Thus, the weights of apterous adults of Ap on excised S-leaves were only 17% greater than on intact S-leaves, whereas they were similar on excised and intact R-leaves. For Af, adult weights were 81% greater on excised R-leaves, 51% greater on excised S-leaves, and only 19% or no greater on excised R- and S-stems, respectively, than those on the corresponding intact plant parts.The possibility is discussed that these contradictory effects result from a mobilization and increase of proteinaceous constituents in the excised plant parts. Whereas the nutrition and growth of aphids on the resistant variety may thus become optimal, such an increase above an already optimal nutrient level on the satisfactory variety would not increase growth beyond the limit already achieved by a species. It is further deduced that postinfestational resistance to aphids of field beans depends on the nutrient value of the sap available to the aphids. However, since the nutritional demands of different aphid species may also differ, it is unlikely that a single plant species will be resistant to aphids in general.

     

ÜBER DIE URSACHEN DER UNTERSCHIEDLICHEN RESISTENZ VON VICIA FABA L. GEGENÜBER DER BOHNENBLATTLAUS APHIS (DORALIS) FABAE SCOP.*

Zusammenfassung Unter der Voraussetzung, daß die Größe ungeflügelter virginoparer Bohnenläuse, Aphis fabae Scop., ein besser geeigneter Parameter für antibiotische Wirkungen ihrer Wirtspflanzen sein dürfte als ihre Tochterproduktion oder Lebensdauer, werden die Faktoren untersucht, welche das larvale Wachstum beeinflussen könnten. Die Größe der Imagines sowie Umfang und Sequenz ihrer Nachkommenproduktion stehen in enger Beziehung zu den Ernährungsverhältnissen, unter denen die Mütter während ihrer Larval- und Imaginalphase leben. Die Entwicklungsgeschwindigkeit nimmt von 5° bis 30° — immer langsamer — zu, das Wachstum aber nur bis 14°; höhere Temperaturen ergeben zunehmend wieder kleinere Imagines. Die Imaginalgröße, die von Läusen auf ausgestanzten Blattscheiben erreicht wird, vermindert sich mit sinkendem Durchmesser bzw. bei ansteigender Populationsdichte. Auf wachsenden Blättern (in situ) entstehen um so größere Imagines, je größer der prozentuale Zuwachs der Blattfläche während der Postembryonalentwicklung ist. Abschneiden und Bewurzeln von Primärblättern beeinflussen die Größe der auf ihnen aufgezogenen Bohnenläuse bei der Ackerbohnensorte Schlanstedter fast nicht, während sie auf Rastatter größere bzw. wieder so kleine Adulte ergeben wie an intakten Pflanzen. Als Ursache aller dieser Wachstumsreaktionen der Bohnenläuse wird die Wüchsigkeit, speziell die Höhe des Aminosäurespiegels im Substrat, angesehen. Die ökologischen Folgen für den Wirtswechsel und die Resistenzerscheinungen werden diskutiert.

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Summary Using the adult size (length, weight, frontal projection of surface) of young virginoparous bean aphids as a parameter for antibiotic effects of the host plant, detailed knowledge is wanted of postembryonic growth reactions of the aphids to different environmental factors.On the same food material daughters of small mothers grow bigger, those of big ones smaller than their mothers, but they still differ significantly from each other. Direction and scope of the size modification between two generations depend on the nutritional difference of the substratum on which mothers and daughters develop.On a substratum of high value and with 20°, big mothers produce nearly two-thirds of their total offspring during the first week and another third in the second week, while the small ones begin only with a quarter. But then they recover with 40% in the second and a quarter in the third week and so they finally reach 84% of the total production of big mothers, though with a retardation of one week. Also the quantitative proportions of embryogenesis during pro- and postmetamorphic development and therefore the sequence of births are results of the nutritional situation during the larval and imaginal stages, respectively, of the virginoparae.Whereas with rising temperature the developmental speed increases in the usual manner —with the minimum at 5° and the maximum not much above 30° —, growth is already optimal at 14–15° and decreases promptly with temperatures above the optimum. Obviously with temperatures too high or too low the surplus of high energy material (amino acids) necessary for growth processes is consumed by the maintenance metabolism or blocked under these conditions. Aphis fabae-virginoparae grown on leaf discs floating upside down on tap water develop into smaller adults as diameters (22–16–10.5 mm) decrease or population density (2, 6 or 20 larvae on 200 mm² leaf disc each) increases (differences significant at the 0,1% level). While on leaves in situ such differences do not prove significant, young virginoparae grow the bigger, the more the leaf area increased relatively during their larval development. Therefore the differences in the antibiotic aphid resistance of young Rastatt and Schlanstedt field bean plants of the same age may be reduced to a difference in phase of the growth of their leaves.On leaf discs of different age the biggest adults develop on discs from mature assimilating foliage, which after isolation may evidently mobilize more protein reserves than younger or older ones, probably as the young leaf itself yet depends on an influx of amino acids, and the old leaf already is more or less exhausted of them.Bean aphids developing on normal intact, detached, or detached and re-rooted primary leaves of the susceptible field bean Schlanstedter show nearly no significant differences in adult size, but on corresponding leaves of the resistant Rastatter they react with increased and decreased growth respectively (in comparison with their normal diminished size). The Schlanstedt field beans provide an uniform and equivalent feeding basis for the growth of black bean aphids during nearly all stages of their physiological development. They represent a main host (host of class I in the sense of Mosbacher). The Rastatt field beans on the other hand are secondary hosts (hosts of class II), which guarantee a sufficient promotion of aphid growth (in the sense of Kennedy et al.) only in stages of an increased mobility of soluble protein elements in growing or senescent organs.

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Quedlinburger Beiträge zur Züchtungsforschung Nr. 72.

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寡糖及多糖甲基化方法的发展及现状

本文综述了在寡糖、多糖结构分析中应用的各种甲基化方法及近年来有关的最新进展,并对它们各自的优、缺点进行了比较。