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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DIE WIRKUNG KOMBINIERTER ANWENDUNG INSEKTIZIDER PHOSPHORSÄUREESTER UND CARBAMATE AUF DROSOPHILA MELANOGASTER1

Zusammenfassung Die Kontaktwirkung von Phosphorestern, Carbamaten und Kombinationen beider Wirkstoffgruppen auf Drosophila melanogaster wurde untersucht.Auf Grund bestimmter Merkmale der Zeit-Wirkungskurven lassen sich drei verschiedene Typen von Phosphorestern unterscheiden.In Kombination mit subletalen Dosen des reversibel wirkenden Carbamats Isolan werden die Wirkungen der Phosphorester in unterschiedlicher Weise verändert.Die möglichen Ursachen für diese Wirkungsunterschiede und Wirkungsveräderungen werden diskutiert.

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Summary Sixteen organic phosphorus insecticides and three insecticidal carbamates were tested per se and in combinations against Drosophila melanogaster.Sublethal doses of the carbamate at first accelerated the effect of parathion, paraoxon, chlorthion, malathion, DDVP, trichlorphon, phosphamidon, and mevinphos (type 1). However, later on the time-response curves indicated retardation of mortality and even recovery of the poisoned flies. Similar results were obtained in combinations with guthion, endothion, G 24747, G 24746, diazinon, and diazoxon (type 2), a group of phosphorus esters the timeresponse curves of which under our conditions are not sigmoidal like type 1, but broken and partly showing a tendency to recovery of the flies.The recovery phenomenon in combinations occurred only when the phosphorus ester uptake by the flies was stopped after a fixed time; thus supplies were cut off, degrading systems could inactivate free phosphorus ester and acetylcholinesterase regenerated from carbamate-blockage was not inhibited anew.The typical sigmoidal time-response curves of EPN and thiometon (type 3) were not altered by combination with carbamates; that may indicate absence of effective enzymes for degrading these compounds.

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Kurzfassung der gleichnamigen Dissertation der landwirtschaftlichen Fakultät.     

PHYSIOLOGISCHE WECHSELBEZIEHUNGEN ZWISCHEN PIERIS BRASSICAE UND DEM ENDOPARASITEN APANTELES GLOMERATUS. DER EINFLUß DER PARASITIERUNG AUF WACHSTUM UND KÖRPERGEWICHT DES WIRTES1

Zusammenfassung Der Parasitismus von Apanteles glomeratus (L.) bewirkt bei den Larven seines Wirtes, Pieris brassicae. L., eine Blockierung des Gewebewachstums und der Reservestoffspeicherung, sobald sich die Parasitenlarven zum 2. Stadium gehäutet haben. Das Ausmaß der durch diese Blockierung bedingten Wachstumshemmung der Wirtsraupe ist von der Anzahl der in ihr vorhandenen Parasitenlarven unabhängig; es scheint jedoch vom Häutungstermin derselben bestimmt zu werden. Gemessen am durchschnittlichen Trockengewicht erwachsener Pieris-Raupen beträgt der Hemmungseffekt zwischen 60% und 80%. Die Stoffwechselkapazität der Wirtsraupen wird trotz der Blockierung nicht eingeschränkt, sondern steht den Entwicklungsbedürfnissen der Parasitenlarven zur Verfügung, wobei der Grad ihrer Inanspruchnahme von der Individuenzahl der Parasitenlarven abhängt.

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Summary Apanteles glomeratus and Pieris brassicae served as models to investigate the parasitic effect on growth and body weight of the host. Three kinds of host larvae were used in the experiments: Aunparasitized larvae, B-larvae being parasitized on the first day after hatching from the egg, and C-larvae parasitized on the sixth day after hatching. Parasitism by A. glomeratus blocks the growth of the host body independently of the number of parasite larvae living in a host, when the dry weight of the host tissues has reached about 20% (in B-larvae) or 40% (in C-larvae) of the final dry weight of the unparasitized host larva. This blocking occurs on the first and about the third day of the host's fifth instar, respectively. Further growth of the host-parasite-system comes from the development of the parasite larvae only, and depends on the number of them present in the host body. In this way slightly parasitized Pieris-larvae remain abnormally small, whereas heavily parasitized ones grow up to a final body weight higher than unparasitized larvae. This effect is apparent in the maximum and the final live weight as well as in the final dry weight of the total system.The blocking effect seems to be induced by the parasite's second-instar larvae, because growth of the host tissues ceases immediately after the moulting of the parasites. At this moment the host larva seems to loose most of its metabolic autonomy and becomes governed by the parasite larvae. The blocking effect, the physiological mechanism of which is not yet understood, is absolute. It preserves about 80% of the host's spatial and nutritional capacity for the development of the parasite larvae. This reserve of space and metabolic potency is completely exhausted only when the number of parasites exceeds 60 or 80 per host larva in B- and C-larvae, respectively; smaller parasite numbers use only a part of this reserve.It is concluded that the Apanteles larvae, being unable to feed on or to destroy solid host tissues, prevent their synthesis by a blocking effect, thereby eliminating the competition of the host body for nutrients absorbed by the host's gut. Because of the varying number of parasite larvae in the range of 1 to 160 the expected nutritional requirement of the parasite larvae present is uncertain in their early stages of development. Preserving about 80% of the host's physiological capacity independently of the number of the moulting parasite larvae, A. glomeratus guarantees conditions sufficient for the development of even an extraordinarily numerous progeny.

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Gefördert durch die Deutsche Forschungsgemeinschaft     

AUSWIRKUNGEN VON INSEKTIZIDBEHANDLUNGEN AUF DIE EPIGÄISCHEN RAUBARTHROPODEN IN GETREIDEFELDERN,INSBESONDERE DIE LAUFKÄFER (COLEOPTERA,CARABIDAE)

Zusammenfassung Die Ergebnisse wurden mit Bodenfallen in Getreidefeldern erarbeitet. Fenitrothion beeinflußte bei Flugzeugausbringung in normaler Dosierung (600 g/ha in 40 1 Wasser) nur die Populationsdichte von Pterostichus vulgaris und P. niger vorübergehend. Eine Spritzung mit erhöhter Dosierung (900 g/ha in 350 1 Wasser) wirkte sehr stark auf die fünf häufigsten Carabidenarten ein. Parathion-äthyl beeinflußte in normaler Dosierung (125 g/ha in 300 1 Wasser) bei einer Behandlung Anfang Juni besonders einschneidend die Frühlingstiere, Ende Juni stark die Frühlings- und die Herbsttiere. In doppelter Dosierung reduzierte es alle wichtigen Prädatorengruppen sehr deutlich. Parathion-methyl (Staub) wirkte bei Ausbringung auf feuchte Pflanzen (200 g/ha) nicht stark auf die epigäischen Räuber. Nur kletternde Arten (Staphyliniden und Agonum dorsale) wurden geschädigt. Methoxychlor wirkte als Spritzmittel (600 g/ha in 300 1 Wasser) stark auf die großen Carabiden, während die kleinen Laufkäferarten, die Staphyliniden und Spinnen nicht beeinflußt wurden. Methoxychlor-Staub, auf die feuchten Pflanzen ausgebracht (1000 g/ha), beeinflußte die epigäischen Räuber nicht. Eine Randbehandlung eines Winterrapsfeldes mit Methoxychlor-Staub störte die Besiedlung des Feldes durch Carabiden und Staphyliniden nicht.

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Summary The influence of some insecticides often used in agriculture upon the terrestrial predaceous arthropods was investigated by pitfall trapping on cereal fields of about 10 hectares each, half the area of which was treated.Fenitrothion, sprayed by aeroplane at the normal dosage (600 g/ha in 40 1 water) influenced the abundance of Pterostichus vulgaris and P. niger only, for a short period. Spraying fenitrothion at a higher dosage (900 g/ha in 350 1 water) killed a high percentage of the five most common carabid species.Parathion-ethyl at the normal dosage (125 g/ha in 300 1 water), sprayed at the beginning of June reduced numbers of spring breeders especially (e.g. Pterostichus cupreus). Sprayed at the end of June, it influenced both spring and autumn breeders (e.g. P. vulgaris). Rain, falling one day after the insecticide treatment, did not alter its effect upon the terrestrial predators. At a higher dosage (250 g/ha) parathion-ethyl reduced numbers of all predators to a large extent, but not very much more than at the normal dosage.Parathion-methyl dust, applied to moist plants (200 g a.i./ha), did not influence all terrestrial predators, but only those species which also climb up the plants (some staphylinids and Agonum dorsale).Methoxychlor emulsion, sprayed at a dosage of 600 g/ha in 300 1 water, killed the bigger ground beetles only (Carabus spp. and P. vulgaris), but not the smaller ones (Agonum dorsale and Bembidion lampros), the staphylinids and the spiders. Methoxychlor, dust, applied to moist plants (1000 g a.i./ha) did not influence the terrestrial predators. Treating the edge only (ca. 20 m) of a winter-rape field with methoxychlor dust did not prevent the colonization of the field by carabids and staphylinids. It is recommended, therefore, to treat the field edges only, which should control most cereal pests.

     

PARASITÄRE VERÄNDERUNGEN DER WIRTSKUTIKULA BEI PIERIS BRASSICAE UND CYDIA POMONELLA DURCH ENTOMOPHAGE ENDOPARASITEN

Zusammenfassung An den Wirt-Parasit-Systemen Pieris brassicae-Apanteles glomeratus sowie Cydia pomonella-Ascogaster quadridentatus wurde der parasitäre Einfluß auf die Kutikula der Wirtsraupen im 5. Stadium histologisch und chemisch untersucht. Die Dickenentwicklung der Exo-und insbesondere der Endokutikula unterliegt einer starken parasitären Hemmung, die bei beiden Wirt-Parasit-Systemen schließlich in einer Reduktion der Dicke und des Trockengewichts um etwa 50% bis 58% resultiert. Der Parasitismus von Apanteles wirkt sich schon in der frühen Aufbauphase der Kutikula auf deren Wachstum und Eigenschaften aus und verändert auch im weiteren Verlauf die Kutikulaentwicklung. Qualitative Veränderungen betreffen die Dichte und chemische Zusammensetzung. Besondere Gewichtsdefizite beim Stickstoff sowie bei der alkalilöslichen Fraktion zeigen an, daß insbesondere der Einbau von Proteinen, aber auch die chemische Stabilisierung des Chitin-Protein-Komplexes gehemmt sind.

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Summary Parasitism by Apanteles glomeratus and Ascogaster quadridentatus affects the development of cuticle of the host larvae, Pieris brassicae and Cydia pomonella, respectively. Inhibitory parasitic effects on cuticular growth of the host during its last larval instar are evident in differences in surface area, thickness and dry weight of the integument. They amount to 32% reduction in surface area, 56% of thickness and 54% of dry weight in Pieris and to 37%, 50% and 58% in Cydia. Thickness of endocuticle is reduced much more than that of exocuticle. This may be due to the continuous influence of the parasite larvae on the deposition of endocuticular material during the intermoult period.Extraction of cuticles with hot water and hot 5% aqueous potassium hydroxide revealed changing differences between the relative amounts of the three fractions, obtained by this treatment. Relative gain of dry weight is less in the alkali-soluble fraction of parasitized Pieris and Cydia. Deficiency of nitrogen (29% to 62% in water extract and 56% to 75% in alkali extract) is generally greater than reduction of total cuticle dry weight. This is more pronounced in the alkali-soluble fraction than in the water extract.These data suggest that the presence of parasites has greatest effect on incorporation of nitrogenous compounds. Moreover, chemical stabilization of the chitin-protein complex seems to stop earlier and to be less perfect in parasitized caterpillars. Since specific gravity of dry cuticle is also subject to effects of parasites, it is assumed that in the investigated hostparasite associations the cuticle of parasitized hosts differs from unparasitized ones in quantity, physical quality and chemical composition.