Neem Azal-T/S, Neudosan and Spruzit flu¨ssig at different concentrations were evaluated against the second and fourth instar larvae of E. chrysomelina under laboratory conditions. In case of acute effects, the highest mortality was recorded when larvae were offered squash leaves treated with the highest concentration (2%) of Neem Azal-T/S, and the lowest mortality was, however recorded after treating them with the lowest concentration (0.25%). On the other hand, the second instar larvae were more susceptible to any compound at any concentration than the fourth instar one. One per cent Neudosan formulation showed the highest toxicity to both the 2nd and 4th instar larvae. As the concentration of this compound decreased the mortality percentage of treated larvae decreased to reach the minimum at the lowest concentration (0.25%). The same trend could be applied for Spruzit flu¨ssig compound. When Neem Azal-T/S was compared with Neudosan, the later at any concentration was more toxic than the former. Generally, Neudosan and Spruzit flu¨ssig seemed to be active against E. chrysomelina during the first three days after treatment, then, deterioration occurred among this compound. In case of latent effects, the duration of the treated fourth instar larvae of E. chrysomelina with any tested compound, was prolonged. An increase in the concentration caused prolongation of this period to reach the longest at the highest concentration. This prolongation, was more pronounced after Neem Azal-T/S treatment followed by Neudosan and Spruzit flu¨ssig. The same trend could be applied for the duration of the pupal stage as being affected by the different concentrations of the tested compounds which were applied to the fourth instar larvae. However, adults of E. Chrysomelina treated as fourth instar larvae with high concentrations of Neem Azal-T/S showed some adult malformations. The sex ratios of adults produced from fourth instar larvae treated with different concentrations of the tested natural compounds were about 1 : 1, except for two cases; 1% Neudosan where the number of females were double the number of males and 0.5% Spruzit flu¨ssig where the number of males were double the number of females. An increase in the concentration of any tested compound caused an obvious decrease in the percentage of emerged adults. The least emergence percentage was recorded in the case of Spruzit flu¨ssig, followed by Neudosan and Neem Azal-T/S. Treating the fourth instar larvae with the different concentrations of the tested natural compounds significantly shortened the longevity of produced adults and decreased the fecundity.
Flies of Genus Platypalpus in cereal crops as predatory insects little noticed hitherto Sweep net and blue‐trap catches carried out in cereal crops of the Halle district in 1985 proved the presence of predatory flies of the genus Platypalpus (Empididae) in great number. The identification of altogether 6506 insects caught in winter wheat, winter and summer barley revealed 12 different species. Most frequently were found Platypalpus articulatoides Frey, P. pallidicornis Coll., P. articulatus Macq. and P. pictitarsis Beck. High population densities were also recorded for P. infectus Coll., P. pallidiventris Meig. and P. minutus Meig. Of faunistic interest might be the identification of totally 18 insects of the species P. excisus Beck. The composition of the insect species settling on the studied crops was very uniform, whereas the dominance structure varied significantly. Proof could be furnished for the presence of Platypalpus in cereal crops nearly throughout the whole growth period. Investigations and tests on the feeding behaviour of the predators demonstrated, that various Platypalpus species feed preferably on Oscinella frit (L.), wheat midges (Contarinia tritici [Kirby] and Sitodiplosis mosellana [Géhin]). The importance of the predatory flies of this genus as regulators of insect populations in grain crops is discussed and available literature is analysed. Zusammenfassung Die räuberisch lebenden Fliegen der Gattung Platypalpus (Empididae) waren in Kescher‐ und Blauschalenfängen in Getreidefeldern des Bezirkes Halte im Jahre 1985 zahlreich vertreten. Die Determination der insgesamt 6506 in Winterweizen‐, Wintergerste‐ und Sommergerstebeständen erbeuteten Individuen erbrachte 12 verschiedene Spezies. Zu den häufigsten Vertretern zählten Platypalpus articulatoides Frey, P. pallidicornis Coll., P. articulatus Macq. und P. pictitarsis Beck. Hohe Individuendichten erreichten weiterhin P. infectas Coll., P. pallidiventris Meig. und P. minutus Meig. Faunistisch bedeutsam ist der Nachweis von insgesamt 18 Individuen der Art P. excisus Beck. Die Artenstruktur in den untersuchten Beständen war sehr einheitlich, während die Dominanzstruktur größere Abweichungen zeigte. Es wurde der Nachweis erbracht, daß Platypalpus‐Arten nahezu während der gesamten Vegetationsperiode in den Getreidebeständen präsent sind. Beobachtungen und Experimente zum Fraßverhaften wiesen Oscinella frit (L.) sowie Weizengallmücken (Contarinia tritici [Kirby] und Sitodiplosis mosellana [Géhin]) als häufig gefangene Beute verschiedener Platypalpus‐Arten aus. Die Bedeutung der Fliegen dieser Gattung als Regulatoren von Insektenpopulationen in Getreidefeldern wird diskutiert und das vorhandene Schrifttum ausgewertet.
Evaluation and utilization of a population model for the English grain aphid Macrosiphum (Sitobion) avenae (F.) An important precondition for the application of a model is its validation. So the main results of the evaluation of the simulation model PESTSIM‐MAC concerning the population dynamics of Macrosiphum (Sitobion) avenae (F.) are discussed. Extensive simulation studies in connection with the analysis of key processes were made to improve the model and to give evidence of the validity. To a large extent the success of the modelling process depends on the quality and quantity of data used. Unfortunately at present there is no sufficient method to count the exact number of aphidophagous insects (expecially Coccinellidae) in relation to a defined area. A catalogue of case studies is presented for field‐related decisions on control of aphids at the end of the flowering period of winter wheat (DC 69). Zusammenfassung Die Einschätzung des Simulationsmodells für die Populationsdynamik von Macrosiphum (Sitobion) avenae (F.) (PESTSIM‐MAC) ist eine wichtige Voraussetzung für die Erarbeitung von Anwendungs‐möglichkeiten. Durch umfangreiche Simulationsstudien, verbunden mit der Analyse von Schlüssel‐prozessen und daraus resultierenden Modellveränderungen, konnte die Validität des Modells nachge‐wiesen werden. Der Erfolg des gesamten Modellierungsprozesses hängt in entscheidendem Maße von der Qualität und Quantität der verwendeten Daten ab. Zur genauen Erfassung der Abundanz von Aphidophagen im Feld ist die Erarbeitung einer praktikablen Methode erforderlich. Für die schlagbe‐zogene Bekämpfungsentscheidung zum Ende der Winterweizenblüte (DC 69) wird ein Fallstudienka‐talog vorgeschlagen.
Studies on interrelationship between Rhopalosiphum padi (L.) and wheat plants in consideration of15N‐distribution In spring wheat heavy infestation by Rhopalosiphum padi (L.) caused a displacement of the 15N absorbed from the substrate to the places of sucking (stalkes, leaves) and off the ears. Simultaneously, yield and 15N‐uptake ability of wheat plants were reduced. Zusammenfassung Starker Befall mit Aphiden der Art Rhopalosiphum padi (L.) bewirkte bei Sommerweizen eine Umverteilung des aus dem Substrat aufgenommenen 15N zugunsten der Saugorte (Halme, Blätter) und zu Lasten der Ähren. Gleichzeitig waren Ertrag und 15N‐Aneignungsvermögen der Pflanzen vermindert.
Model experiments on infestation‐damage relations using insect pests of winter wheat For the realisation of the desired measures of plant protection is the knowledge about the processes which lead to insect damage in crops essential At examples of the wheat bulb fly (Leptohylemyia coarctata Fall.), the cereal leaf beetles (Oulema spp.) and the English grain aphid (Macrosiphum avenae [Fabr.]) on one side and the winter wheat on other side should analysed such infestation‐damage‐relations on the basis of model experiments carried out for several years with the help of mathematical‐statistical methods. The numerous single findings were the reasons to formulate some conclusions. The investigations have led to infestation levels for the chemical plant protection measures. These are 60–90 eggs/m2 ground in autumn for the Leptohylemyia coarctata Fall., 1–1,5 eggs and larvae/flag leaf for Oulema spp. at the time of heading and 3–5 aphids/ear during the flowering of wheat for Macrosiphum avenae (Fabr.). Zusammenfassung Zur Realisierung gezielter Maßnahmen des Pflanzenschutzes sind Kenntnissee über die Prozesse der Schadensentstehung und der Schadwirkung von Insekten an Kulturpflanzen unerläßlich. Am Beispiel der Brachfliege (Leptohylemyia coarctata Fall.), der Getreidehähnchen (Oulema spp.) und der Getriedelaus (Macrosiphum avenae [Fabr.]) einerseits und des Winterweizens andereseits werden derartige Befall‐Schadens‐Relationen auf der Grundlage mehrjähriger, modellartiger Versuche mit Hilfe mathematisch‐statischer Prüfverfahren analysiert. Die zahlreichen einzelnen Befunde waren Veranlassung, einige thesenartige Schlußfolgerungen über die Wechselwirkung von Schadinsekt und Kulturpflanze zu formulieren. Die Untersuchungen haben zur Ableitung von Richtwerten für die Durchführung chemischer Pflanzenschutzmaßnahmen geführt. Diese lauten für Leptohylemyia coarctata Fall. 60–90 Eier/m2 Boden in Herbst, für Oulema spp. 1‐1,5 Eier und Larven/Fahnenblatt zur Zeit des Ährenschiebens und für Macrosiphum avenae (Fabr.) 3–5 Aphiden/Ähre während der Blüte des Weizens.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.