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  • 1
    Electronic Resource
    Electronic Resource
    Experimental inundative releases of different strains of the egg parasite Trichogramma in Brussels sprouts (1989)
    Springer
    European journal of plant pathology 95 (1989), S. 129-142 
    Details
    ISSN: 1573-8469
    Keywords: biological control ; egg parasites ; Brussels sprouts ; Mamestra brassicae ; Pieris brassicae ; Pieris rapae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Samenvatting In spruitkool kan schade veroorzaakt worden door rupsen van vijf soorten Lepidoptera. Inundatieve biologische bestrijding met de eiparasietTrichogramma (Hymenoptera, Trichogrammatidae) zou een alternatief kunnen zijn voor intensieve chemische gestrijding. In veldexperimenten (1982–1985) is de effectiviteit van vierTrichogramma spp. stammen vergeleken om de uitkomsten van laboratoriumonderzoek naar criteria voor de selectie van geschikte natuurlijke vijanden te evalueren. Selectiecriteria zijn gebaseerd op eigenschappen van het zoek- en parasiteringsgedrag van de parasieten, o.a. parasiteringsactiviteit bij lage temperatuur en gastheer-preferentie. Mamestra brassicae (Noctuidae) was de talrijkste gastheersooort, met een gemiddelde dichtheid van 0,2–2,0 eieren/plant gedurende een groot deel van het seizoen (juni–september). Een extreem hoge piekdichtheid (12 eieren/plant) deed zich voor in 1982. In andere jaren was de piekdichtheid ongeveer 2,5 eieren/plant. Eieren vanM. brassicae werden het meest geparasiteerd door stam 57 (T. evanescens), maar zelfs het hoogste gemiddelde seizoenspercentage parasitisme (52%) was niet voldoende voor een effectieve bestrijding. EenT. maidis stam (11) gaf de beste resultaten tegenPieris brassicae enP. rapae (Pieridae), maar parasitisme was laag (〈30%) en vrijwel beperkt tot piekdichtheden hoger dan 0,5 eieren/plant, die voorkwamen in 1982 en 1985.Plutella xylostella (Plutellidae) was soms talrijk, maar eiparasitisme leek niet voor te komen. De dichtheid vanEvergestis forficalis (Pyralidae) was gering in alle jaren. Relatief lage gastheerdichtheden kunnen een beperkende factor geweest zijn voor het optreden van een effectieve percentages eiparasitisme. De resultaten tonen aan dat er een overeenstemming is tussen selectiecriteria die in het laboratorium zijn onderzocht en de effectiviteit van geselecteerde stammen in het veld.
    Notes: Abstract The effectiveness of inundative releases of four strains of the egg parasiteTrichogramma (Hymenoptera, Trichogrammatidae) to control five lepidopterous species infesting Brussels sprouts crops in the Netherlands was examined in small-scale field experiments in 1982–1985. Strains were selected on the basis of behavioural characteristics investigated in laboratory experiments, i.e. parasitization activity at low temperature and host-species preference.Mamestra brassicae (Noctuidae) was the most abundant host species. Its density usually averaged between 0.5 and 2.0 eggs/plant throughout most of the season (June–September). A very high peak density of 12 eggs/plant occurred in 1982. In other years the peak was below 2.5 eggs/plant. Correspondence between the observed patterns of parasitism and behavioural characteristics of the strains was in general present. A strain ofT. evanescens (no. 57), with a high activity at 12°C, performed best againstM. brassicae. However, even its highest rate of parasitism (52%) was not sufficiently effective. A strain ofT. maidis (no. 11) performed best againstPieris brassicae andP. rapae (Pieridae), but parasitism remained low (〈30%) and was generally limited to peak densities (〈0.5 eggs plant) occurring in 1982 and 1985.Plutella xylostella (Yponomeutidae) was an abundant species in some years, but parasitism of its eggs was never observed. Egg densities ofEvergestis forficalis (Pyralidae) remained low in all years. The relationship between parasitims and host density and the influence of the parasite-release rate are discussed. Low host densities may have been a limiting factor for effective parasitism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01999968
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  • 2
    Electronic Resource
    Electronic Resource
    Genetic variability in the reactive distance inTrichogramma brassicae after automatic tracking of the walking path (1994)
    Springer
    Entomologia experimentalis et applicata 72 (1994), S. 297-303 
    Details
    ISSN: 1570-7458
    Keywords: reactive distance ; walking path analysis ; Trichogramma ; genetic variability ; Ephestia kuehniella ; Mamestra brassicae ; glass beads ; simulation model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Efficiency of hymenopterous parasitoids to control pests in a biological control release program probably increases with increasing searching ability of the females, which, in return, likely depends on the distance from which females perceive their hosts (i.e., reactive distance). In this study, we first analyse this hypothesis with the help of a stochastic model simulating the walking path of isolatedTrichogramma females during their searching behaviour. Then, this reactive distance is estimated using automatic recording and analysis of the walking path of female wasps. Finally, the genetic variability for this trait is analysed in aTrichogramma brassicae Bezdenko (Hym.; Trichogrammatidae) population. Three types of hosts were used: Eggs ofEphestia kuehniella Zeller (Lep.; Pyralidae), eggs ofMamestra brassicae L. (Lep.; Noctuidae) and 0.45 mm glass beads.M. brassicae eggs are perceived from 4.01±0.15 mm, which is a significantly longer perceptive distance than forE. kuehniella eggs (3.69±0.10 mm) and glass beads (3.67±0.10 mm). Moreover, whatever the host tested, a significant genetic variation is observed in this trait in the population studied. The ecological and evolutionary implications and the agronomical importance of these results are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02383818
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  • 3
    Electronic Resource
    Electronic Resource
    Behavioural variations among strains of Trichogramma spp.: Host-age selection (1986)
    Springer
    Entomologia experimentalis et applicata 40 (1986), S. 247-258 
    Details
    ISSN: 1570-7458
    Keywords: Trichogramma ; egg parasites ; biological control ; host ages ; host selection ; host discrimination ; parasitization behaviour ; optimal foraging ; Mamestra brassicae ; Pieris brassicae ; Pieris rapae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Afin de sélectionner une souche candidate de Trichogramma sp. pour des lâchés inondatifs contre les Lépidoptères, pestes du chou aux Pays-Bas, la sélection hôte-âge de plusieurs souches de Trichogramma spp., issues d'un éventail de 60 souches, a été examinée en laboratoire par des tests de choix. Le comportement de femelles individuelles, mises en présence de combinaisons d'oeufs-hôtes d'âges différents (zero ou 2 jours et 1 ou 3 jours) des espèces-hôtes Mamestra brassicae, Pieris brassicae et P. rapae, a été observé directement. En général, l'âge de l'hôte ne semble pas affecter le contact et l'acceptation des oeufs quelque soit l'espèce-hôte. La ponte diminue généralement dans les oeufs les plus âgés de M. brassicae, mais pas chez les autres espèces. La durée du comportement de ponte est parfois influencée par l'âge de l'hôte. Toutes les souches ont montré la capacité de discriminer entre les hôtes parasités et nonparasités, a l'examen externe ou interne et ceci, indépendamment de l'âge de l'hôte. Le manque de variation parmi les souces suggère que le mode de sélection hôte-âge est surtout caractéristique de l'espèce-hôte. Les resultats sont discutés en relation avec la théorie de fourrage optimal.
    Notes: Abstract Host-age selection by several Trichogramma spp. strains was examined in laboratory choice-tests, in order to use this as a criterion to select a candidate strain for inundative releases against lepidopterous pests of cabbage in the Netherlands. The behaviour of individual females toward combinations of host eggs of two different ages (zero vs 2 and 1 vs 3-day-old) of the host species Mamestra brassicae, Pieris brassicae and P. rapae was observed directly. Host age generally did not appear to affect contact or acceptance of eggs of either host species, except that oviposition was generally lower in the oldest M. brassicae eggs. The duration of the oviposition behaviour was sometimes influenced by host-age. All strains were able to discriminate between parasitized and unparasitized hosts by external or internal examation. The lack of variation among the strains suggests that the host-age selection pattern of a given host-Trichogramma combination is predominantly dependent on the host species. The results are discussed in relation to optimal foraging theory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00293707
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  • 4
    Electronic Resource
    Electronic Resource
    Behavioural variation among strains ofTrichogramma spp.: host-species selection (1990)
    Springer
    Entomologia experimentalis et applicata 56 (1990), S. 91-102 
    Details
    ISSN: 1570-7458
    Keywords: Trichogramma ; egg parasites ; biological control ; host selection ; preference ; parasitization behaviour ; host discrimination ; Mamestra brassicae ; Pieris brassicae ; Pieris rapae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Le comportement de sélection de l'hôte par neuf souches deTrichogrammes, vis-à-vis d'œufs deMamestra brassicae, Pieris brassicae etP. rapae a été étudié au laboratoire afin de sélectioner des souches candidates pour des lâchers inondatifs contre ses espèces. Des expériences ont été menées par observations en continu du comportement de femelles auxquelles était offert un nombre égal d'œufs de deux espèces d'hôtes, disposés selon un grille.M. brassicae est un espèce-hôte fortement acceptée par toutes les souches. Au contraire, l'acceptabilité des deux espèces dePieris, semblable pour chaque souche, varie entre les souches. En tenant compte de la variation d'acceptance des œufs dePieris les souches (1) ne montrent aucune préférence entreMamestra etPieris, (2) montrent une préférence pourMamestra, ou(3) une aversion pourPieris. Des femelles des souches du second groupe acceptent fortement les œufs dePieris si les œufs deMamestra, préférés, sont absents. Comparativement, elles rentrent en contact avec moins d'œufs dePieris en présence d'œufs deMamestra. Ceci indique une sélection des hôtes à distance. Les souches du premier groupe sont probablement les meilleures candidates pour des lâchers inondatifs.
    Notes: Abstract The host-selection behaviour of nine strains ofTrichogramma spp., towards eggs ofMamestra brassicae, Pieris brassicae andP. rapae, was investigated in laboratory experiments in order to select candidate strains for inundative releases against these species. Experiments were carried out by continuously observing the behaviour of individual females, which were offered equal numbers of eggs of two host species arranged in a grid.M. brassicae was a highly acceptable host species for all strains, whereas the acceptability of the twoPieris species was similar within strains, but varied between strains. Considering the variation in acceptance ofPieris eggs, strains either showed: (1) no preference betweenMamestra andPieris (High PierisAcceptance = HPA strains), (2) a preference forMamestra (Variable PierisAcceptance = VPA strains), or (3) an aversion forPieris (Low PierisAcceptance = LPA strains). Females of VPA strains showed a high acceptance ofPieris eggs if the preferredMamestra eggs were absent. They contacted comparatively fewerPieris eggs in presence ofMamestra eggs, which indicates selection of hosts at a distance. HPA strains probably are the best candidates for inundative releases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00579618
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  • 5
    Electronic Resource
    Electronic Resource
    Changes in host acceptance and host suitability as an effect of rearing Trichogramma maidis on a factitious host (1989)
    Springer
    Entomologia experimentalis et applicata 52 (1989), S. 229-238 
    Details
    ISSN: 1570-7458
    Keywords: Trichogramma maidis ; host acceptance ; host suitability ; parasitoid quality ; mass rearing ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Wirtsakzeptanz und Wirtseignung von Ostrinia nubilalis Hbn. für den Eiparasitoiden, Trichogramma maidis Pint. et. Voeg., wurden untersucht nach der Zucht auf dem natürlichen Wirt, O. nubilalis, oder auf dem Ersatzwirt, der Mehlmotte, Ephestia kühniella Zell.. Versuche mit Käfigen, in denen je zwei Maispflanzen mit insgesamt 30 Eigelegen von O. nubilalis und 40 Weibchen von T. maidis eingesperrt waren, zeigten, dass Weibchen, die seit über 150 Generationen auf O. nubilalis bzw. E. kühniella gezüchtet worden waren, die Eigelege gleich gut fanden. Während die auf O. nubilalis gezüchteten Parasitoide die Eigelege zu 80% parasitierten, war die Parasitierungsrate der auf E. kühniella gezüchteten Parasitoide gleich Null. Die Ursachen dieses Phänomens wurden in weiteren Versuchen durch direkte Beobachtungen über Wirtsakzeptanz und Wirtseignung untersucht. Einzelne Weibchen von Stämmen, die nur auf O. nubilalis oder während einer zunehmenden Generationenzahl auf E. kühniella gezüchtet worden waren, untersuchte man während 15 Minuten unter der Stereoskoplupe in einer kleinen Arena, die ein Eigelege des Maiszünslers oder Eier der Mehlmotte enthielt. Dabei zeigte sich, dass Wespen, die ausschliesslich auf Maiszünslereiern oder nur 1–3 Generationen auf Mehlmotteneiern gezüchtet worden waren, die Eigelege von O. nubilalis besser akzeptierten als solche, die seit vielen Generationen auf E. kühniella vermehrt worden waren. Die Wirtsakzeptanz verschlechterte sich mit zunehmender Generationenzahl auf E. kühniella. Wenn T. maidis nach 23 Generationen auf E. kühniella wieder während 5 Generationen auf O. nubilalis gezüchtet wurde, verbesserte sich die Akzeptanz der Eigelege von O. nubilalis nicht. Die Wirtseignung der Eigelege von O. nubilalis, stimmt überein mit der Wirtsakzeptanz der verschiedenen Stämme. Dies ergaben Versuche mit 15 Minuten Direktbeobachtung und bei 24 Stunden Expositionszeit. Im Gegensatz zu den Beobachtungen auf Eigelegen von O. nubilalis wurde die Akzeptanz und Eignung der Eier von E. kühniella durch die Zucht auf verschiedenen Wirten nicht beeinflusst. Das Ergebnis dieser Untersuchung zeigt, dass Akzeptanz und Eignung des natürlichen Wirtes wichtige Qualitätsfaktoren für T. maidis in der Massenzucht auf Ersatzwirten sind.
    Notes: Abstract Host acceptance and suitability of Ostrinia nubilalis Hbn. for Trichogramma maidis Pint. et Voeg. (Hymenoptera: Trichogrammatidae) were studied, after rearing the parasitoids on O. nubilalis or Ephestia kuehniella Oliv. (Lepidoptera: Pyralidae) for various numbers of generations. In cages, containing two maize plants with in total 30 egg masses of the natural host (O. nubilalis), wasps continuously reared on either E. kuehniella or O. nubilalis found egg masses in equal proportions. The former however, did not parasitize the eggs successfully, due to either low degree of host acceptance or insufficient host suitability or both. Subsequently, host acceptance behaviour of individual females from different strains was studied by means of direct observations after releasing them into a small arena containing eggs of O. nubilalis or E. kuehniella. Wasps continuously reared on O. nubilalis or 1–3 generations on E. kuehniella accepted egg masses of the natural host better than wasps continuously reared on E. kuehniella. Acceptance of O. nubilalis by the wasps gradually decreased with increasing numbers of generations reared on E. kuehniella. By rearing T. maidis, previously cultured on E. kuehniella, for five generations on O. nubilalis, acceptance of egg masses of this host species did not change. Host suitability of O. nubilalis appears to correspond with host acceptance of the strains. Contrary to the observations on O. nubilalis, acceptance and suitability of E. kuehniella were not influenced by the host on which T. maidis was reared. Results of this study show that host acceptance and suitability of the natural host are important quality factors for T. maidis when mass produced on a factitious host.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00414048
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  • 6
    Electronic Resource
    Electronic Resource
    Behavioural variations among strains of Trichogramma spp.: Adaptability to field-temperature conditions (1985)
    Springer
    Entomologia experimentalis et applicata 38 (1985), S. 3-13 
    Details
    ISSN: 1570-7458
    Keywords: Hymenoptera ; Trichogramma ; strains and species ; variations ; biological control ; candidate selection ; activity ; low temperature ; inundative releases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Afin de sélectionner une souche de Trichogramma sp. (Hymenoptera, Trichogrammatidae) candidate pour des lâchés inondatifs contre les Lépidoptères pestes de chou aux Pays-Bas, l'activité de parasitisation d'une collection de 60 souches différentes de Trichogramma spp. a été étudiée à 12°C pendant des durées d'exposition de 2 h et 24 h. L'activité proportionnelle et le degré de parasitisation des femelles varient significativement selon des souches et ne sont par corrélés. Ceci suggère l'action des deux mécanismes distincts, dépendant de la température et contrôlant independamment chacun de ces processus. Les souches indigènes sont caractérisées par une faible activité à 12°C, mettant en doute leur utilisation pour les lâchés inondatifs. Dans 3 souches testées à 12, 17, 20, 25 et 30°C, l'activité augmente linéairement avec la température, jusqu'a ce que quasi toutes les femelles parasitent les oeufs hôtes à 20°C et 25°C. Le taux de parasitisation augmente avec la température atteignant un maximum à 20–25°C puis diminue à 30°C. Le temps de manipulation d'un oeuf hôte diminue asymptotiquement lorsque la température croît. Les résultats de cette étude suggèrent que la capacité d'adaptation aux températures basses varie selon les souches de Trichogramma. Cette caractéristique constitue un critère utile pour l'évaluation de souches candidates potentielles.
    Notes: Abstract In order to select a candidate strain of Trichogramma sp. for inundative releases against lepidopteran pests in cabbage field-crops in the Netherlands, the parasitization activity of a collection of 60 different Trichogramma spp. strains was studied during 2 h and 24 h exposures at 12°C. Activity and parasitism varied significantly among strains and the two characteristics were not correlated, suggesting the action of two differentially temperature-dependent mechanisms influencing both characteristics. Native strains were characterized by a low activity at 12°C, making their usefulness for inundative releases doubtful. In three strains tested at 12, 17, 20, 25 and 30°C, activity increased linearly with temperature, until nearly all females parasitized at 20 or 25°C. Parasitism increased with increasing temperature to a maximum at 20–25°C and declined at 30°C. Handling time decreased asymptotically with increasing temperature. The results of this study suggest that Trichogramma strains vary in adaptability to low temperature, making this characteristic a useful criterion for evaluation of candidate strains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00163346
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  • 7
    Electronic Resource
    Electronic Resource
    Epidemiology and simulation of population development of Sitobion avenae in winter wheat (1979)
    Springer
    European journal of plant pathology 85 (1979), S. 197-220 
    Details
    ISSN: 1573-8469
    Keywords: Aphidius uzbekistanicus ; A. picipes ; Chrysopa carnea ; Coccinella septempunctata ; Entomophthora ; Metopolophium dirhodum ; Praon volucre ; Rhopalosiphum padi ; Syrphus corrolae ; simulation techniques
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Samenvatting De toenemende betekenis van graanbladluizen (vooralSitobion avenae) gepaard gaande met een sterke toename van het gebruik van insecticiden op granen maakte verbetering van de prognose over het schadelijk optreden wenselijk. Door gedetailleerde tellingen in het veld (Fig. 1–7) werden gegevens verkregen over het verloop van de epidemie en het optreden van natuurlijke vijanden in 1975, 1976 en 1977. Een immigratieperiode tot in de bloei kon worden vastgesteld. Daarna lijkt de aantrekkelijkheid van het gewas voor alate luizen te verminderen. De alate immigranten krijgen aptere nakomelingen. Deze vormen de stuwende kracht van de populatiegroei. De nakomelingen van apteren zijn merendeels alaat. Zij verlaten het gewas. Een model van de populatieontwikkeling gedurende de epidemie werd opgesteld. De relatiediagrammen Fig. 9 en 10 laten groei en ontwikkeling vanS. avenae en een predator (Syrphus corollae) zien. Kwantificering van de betrekkingen werd mogelijk door literatuurgegevens en laboratoriumexperimenten. Met het model kon de populatieontwikkeling vanS. avenae vanaf begin juni tot aan de populatiepiek in 1975, 1976 en 1977 vrij goed worden gesimuleerd (Fig. 12). Ook de populatieopbouw kon worden gesimuleerd (Fig. 14). De teruggang van de populatiedichtheid blijkt moeilijker te voorspellen door het ontbreken van gegevens over natuurlijke vijanden. Het lijkt waarschijnlijk dat in de toekomst met het model een prognose over de piek van de bladluispopulatie circa 3 weken tevoren mogelijk zal zijn.
    Notes: Abstract The epidemiology ofSitobion avenae and its natural enemies in winter wheat was studied in 1975, 1976 and 1977. Immigration was important until the end of flowering. The alate immigrants had apterous offspring. These became the driving force in population growth. Their offspring were mostly alatae which usually left the field. A model of the epidemic was developed. Quantitative relations between the aphids and their environment were obtained from literature or established in laboratory trials. The model simulated population development and population composition from the beginning of June till the population peak at the end of June or early in July. Because quantitative data on relations between aphids and their natural enemies and pathogens are scarce, and since the knowledge on wing formation is still limited, the population collapse could not be predicted. In the future, prognosis over a period of three weeks seems possible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01976821
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  • 8
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    Automated analysis of hot spot X-ray images at the National Ignition Facility (2016)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2016-09-03
    Description: At the National Ignition Facility, the symmetry of the hot spot of imploding capsules is diagnosed by imaging the emitted x-rays using gated cameras and image plates. The symmetry of an implosion is an important factor in the yield generated from the resulting fusion process. The x-ray images are analyzed by decomposing the image intensity contours into Fourier and Legendre modes. This paper focuses on the additional protocols for the time-integrated shape analysis from image plates. For implosions with temperatures above ∼4 keV, the hard x-ray background can be utilized to infer the temperature of the hot spot.
    Print ISSN: 0034-6748
    Electronic ISSN: 1089-7623
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Published by American Institute of Physics (AIP)
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