DIE WIRKUNG VON PHYTOHORMONEN AUF KEIMUNG UND ENTWICKLUNG VON FARNPROTHALLIEN IV. DIE WIRKUNG VON UNTERSCHIEDLICHEN GIBBERELLINE UND VON ALLO-GIBBERINSAURE AUF DIE AUSLOSUNG DER ANTHERIDIENBILDUNG BEI ANEMIA PHYLLITIDIS L. UND EINIGEN POLYPODIACEEN

The relative activities of seven gibberellins have been testedin their ability to induce antheridia in prothallia of Anemiaphyllitidis. The spectrum of activities differs from the spectradescribed for other gibberellin reactions. Allogibberic acidproved to be highly active in the Anemia test. Additionallyit causes a change in the polarity of the germinating spore.Under the influence of this compound the primary rhizoid istransformed into an additional chloronema. In high concentrationsof allogibberic acid more than 80% of the prothallia developinto those "twins". Out of the polypodiaceous ferns only fewspecies respond to gibberellin application. The relations between chemical structure and activity of differentgibberellins are discussed. (Received January 17, 1966; )     

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     

DIE WIRKUNG VERSCHIEDENER, ÜBER DIE PFLANZE ZUGEFÜHRTER ANTIBIOTICA AUF ENTWICKLUNG UND FERTILITÄT DER SCHWARZEN BOHNENBLATTLAUS APHIS FABAE

Zusammenfassung Unter dem Einfluss verschiedener Antibiotica wird die Larvalentwicklung von Bohnenblattläusen stark gehemmt. Diese Substanzen bedingen ausserdem geringere Größe und vermindertes Gewicht der Aphiden im Vergleich zu unbehandelten Kontrolltieren. Je nach Art und Konzentration des verwendeten Antibioticums bleiben die Aphiden entweder völlig steril oder ihre Reproduktionsfähigkeit wird unterschiedlich stark herabgesetzt. Bereits eine einbis zweitägige Terramycinaufnahme durch Aphiden während des ersten Larvenstadiums ist ausreichend, um beim adulten Tier völlige Sterilität hervorzurufen.

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Summary A considerable delay in larval development of black bean aphids was observed when they were kept permanently on Vicia faba plants in solutions containing antibiotics. The reduction in the weight and size of the aphids on treated plants were also marked in comparison with those on untreated plants. Furthermore, total sterility was observed in certain cases and reduced reproductive rate in others. This effect was related to the chemical constitution, and the concentration of the antibiotics tested. The most effective substances were: terramycin, aureomycin, tetracyclin, chloramphenicol, and reverin. All other antibiotics had none or only a slight impact on reproduction. Even when young larvae fed for a short period (one or two days) on terramycin treated plants, total sterility resulted. The relation between the larval development and reproductive rate of aphids, and the destruction of their symbiotes by antibiotics is discussed.

     

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.