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  • 21
    Electronic Resource
    Electronic Resource
    The differential effects of ingested tannic acid on different species of Acridoidea (1980)
    Springer
    Entomologia experimentalis et applicata 28 (1980), S. 158-166 
    Details
    ISSN: 1570-7458
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Wachstum und Entwicklung von 15 Acridoidea-Arten wurde studiert und zwar mit und ohne Zugabe von Tanninsäure zur Nahrung in Konzentrationen bis zu 20% Trockensubstanz. In keinem Fall wurde die Verdauung beeinträchtigt; nur in den hohen Konzentrationen wurde die Futteraufnahme gesichert vermindert. Polyphage Arten zeigten keine ungünstige Effekte, und bei zwei Arten wirkte Tannin günstig. Dagegen wurde bei grasfressenden Heuschrecken das Wachstum reduziert, und die Überlebensrate war gering. Der Unterschied liegt im wesentlichen darin, dass bei grassfressenden Arten Tanninsäure in die peritrophische Membran eindringt und das Mitteldarmephithel beschädigt, wobei es zu Läsionen kommt und wobei Tannin in die Körperhöhle gelangt.
    Notes: Abstract The growth and development of fifteen species of Acridoidea were studied, with and without the addition of tannic acid in concentrations of up to 20% dry weight. In no case was digestion disturbed, and only at the high levels was there a significant reduction in consumption. Polyphagous species showed no deleterious effects, and in two species tannin was beneficial, while graminivorous acridids showed reduced growth rates and poor survival. The difference lies mainly in the fact that tannic acid penetrates the peritrophic membrane in the graminivorous species, and causes damage to the midgut epithelium with the eventual development of lesions and the occurrence of tannin in the haemocoel.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00287124
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  • 22
    Electronic Resource
    Electronic Resource
    Comparisons of deterrency and toxicity of selected secondary plant compounds to an oligophagous and a polyphagous acridid (1988)
    Springer
    Entomologia experimentalis et applicata 46 (1988), S. 241-247 
    Details
    ISSN: 1570-7458
    Keywords: Schistocerca ; Locusta ; deterrence ; toxicity ; plant secondary compounds ; grasshopper feeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé La comparaison a porté sur les relations entre répulsion et toxicité de huit substances secondaires chez deux acridiens: Locusta migratoria, spécialiste de graminées, et Schistocerca gregaria, polyphage. L. migratoria est repoussé par toutes les substances proposées, aux concentrations naturelles, pour lesquelles S. gregaria a présenté des comportements trés divers. Mais surtout, L. migratoria a été significativement plus sensible que S. gregaria aux effets toxiques de ces substances quand elles sont injectées dans son haemolymphe; S. gregaria a réagi à ces substances plus par des modifications de son comportement. Il y a une corrélation significative pour les deux espèces, entre la répulsion et la toxicité des substances injectées.
    Notes: Abstract A comparison was made of the relationship between deterrence and toxicity of eight secondary compounds to two acridids. The grass specialist Locusta migratoria was compared with the polyphagous Schistocerca gregaria. L. migratoria was deterred by all compounds presented at natural concentrations to which S. gregaria showed a variety of behavioral responses. Overall, L. migratoria was significantly more susceptible to toxic effects of the chemicals when injected into the hemolymph than was S. gregaria and was more sensitive behaviourally to them. There was a significant correlation in both species between deterrency and toxicity of injected compounds, but little evidence of a relationship between deterrency and oral toxicity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00364195
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  • 23
    Electronic Resource
    Electronic Resource
    Host specificity in phytophagous insects: selection pressure from generalist predators (1988)
    Springer
    Entomologia experimentalis et applicata 49 (1988), S. 131-140 
    Details
    ISSN: 1570-7458
    Keywords: evolution ; monophagy ; polyphagy ; host range ; Vespidae ; caterpillars ; predation ; Mischocyttarus flavitarsus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The narrow host range of insect herbivores is noted, and some of the reasons why specificity has evolved are reviewed. Works indicating the need for new approaches are pointed out including the possibility that generalist predators provide a suitable pressure. Experiments to test the hypothesis that generalists are more vulnerable than specialists to predators are described. They involved a vespid wasp and over thirty species pairs of caterpillars, matched for size and density. Overall, generalists were taken more readily than specialists: some but not all reasons could be detected. The results are discussed in ecological and evolutionary terms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00188246
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  • 24
    Electronic Resource
    Electronic Resource
    Plant secondary compounds deterrent but not toxic to the grass specialist acridid Locusta migratoria: Implications for the evolution of graminivory (1990)
    Springer
    Entomologia experimentalis et applicata 54 (1990), S. 53-56 
    Details
    ISSN: 1570-7458
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé 6 composés secondaires végétaux: sinigrine, acide caféique, acide vanilique, linamarine, amygdaline et gramine, très répandus dans la nature, se montrent phagodissuasifs pour le spécialiste de graminées, Locusta migratoria. C'est pourquoi leurs effects après ingestion sont examinés sur tous les stades larvaires. Pour mettre en évidence une influence éventuelle, les expériences sont réalisées avec une ration alimentaire correspondant à la moitié de celle qu'absorbent des criquets consommant à volonté. Dans un cas, l'addition d'un composé secondaire dans le régime alimentaire (amygdaline) produit une augmentation significative du taux de croissance. La discussion porte sur les conséquences évolutives de ces résultats.
    Notes: Abstract Six plant secondary compounds that are quite widespread in nature were shown to be deterrent to the grass specialist, Locusta migratoria. These were then tested for their post-ingestional effects over the whole of the last larval instar. To enhance the possibility of an effect, experiments were conducted where the food ration was less than half of that normally taken by insects feeding ad libitum. In no case was there any indication of a detrimental effect or any trend suggesting one. In one case (amygdalin) there was a significant increase in growth rate with the addition of the secondary compound to the diet. The evolutionary implication of these findings are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00353986
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  • 25
    Electronic Resource
    Electronic Resource
    Oral dosing of insects with feeding deterrent compounds (1989)
    Springer
    Entomologia experimentalis et applicata 52 (1989), S. 119-133 
    Details
    ISSN: 1570-7458
    Keywords: Deterrence ; habituation ; oral dosing ; toxicity ; deterrent-masking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Resumé Des essais préliminaires ont porté sur les différentes techniques de dosage de produits qui normalement inhibent la prise de nourriture. L'isolement des composés hydrosolubles dans des liposomes a donné des résultats prometteurs pour les dissuadants puissants, bien qu'au cours d'absorptions expérimentales de liquide beaucoup de dissuadants aient perdu de leur efficacité. La microencapsulation, en les enfouissant dans une matrice de polymère pour former des sphères sans véritable paroi, peut avoir masqué le pouvoir dissuadant des produits lipophiles, mais n'a pas masqué suffisamment le goût des produits hydrosolubles. La microencapsulation dans des capsules de gélatine a été efficace avec les colorants liposolubles, la paroi de la capsule semblant détruite très rapidement après ingestion. Le revêtement de fines particules par de la cire n'a pas masqué efficacement l'effet dissuasif de la quinine, mais a été valable avec les produits insolubles dans les lipides. L'encapsulation moléculaire de l'acide grindellique dans de la cyclodextrine a masqué son effect dissuasif pour [?]Schistocerca gregaria. Les larves ont mangé le tout pendant les second et troisième stades et ont présenté un ralentissement du développement pendant le troisième stade sans diminuation de la consommation. L'étude comportementale de l'administration de produits dissuasifs comprend l'action de boire et l'accoutumance. Certains produits qui réduisent la consommation de feuilles ont été absorbés en quantités suffisantes avec l'eau de boisson pour donner des doses significatives avec une ou deux prises de liquide par jour. Des larves de Pseudaletia unipuncta alimentées avec du blé traité à la nicotine pendant les cinquième et sixième stades, ont consommé moins que les témoins, mais seulement pendant les 24 premières heures de l'expérience. La prolongation d'un jour, de la durée de développement, a été attribuée au temps nécessaire à l'accoutumance.
    Notes: Abstract A preliminary assessment was made of a variety of approaches to dosing insects with compounds that normally deter feeding. Enclosing water-soluble compounds in liposomes has promise for strong deterrents, although in drinking assays many deterrents lose their potency anyway. Microencapsulating compounds by embedding them in a polymer matrix to form spheres without a true barrier wall may have masked deterrency of a lipophilic compound, but did not adequately mask the taste of water-soluble compounds. Microencapsulation with gelatin was shown to work with lipid-soluble dye and the capsule walls appear to be broken down very rapidly after ingestion. Coating fine particles with beeswax did not successfully mask the deterrence of quinine, but has value with compounds insoluble in lipids. Starch coating can be effective for insects lacking salivary amylase. Molecular encapsulation of grindelic acid in cyclodextrin masked its deterrency to Schistocerca americana. Nymphs fed this material through the second and third instars showed an increase in development time during the third instar without any corresponding reduction in consumption rate. Behavioral approaches to administering deterrent compounds include drinking and habituation. Some compounds that reduce consumption of leaf material were taken in drinking water in amounts sufficient to give relevant doses in one or two drinks daily. Pseudaletia unipuncta larvae fed nicotine-treated wheat through the fifth and sixth instars ate less than control larvae during the first 24 h of the experiment but showed no reduction in consumption after that period. A one-day increase in development time was attributed to the one-day habituation period. More work is needed on the release of taste-masked compounds in the gut.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00163246
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  • 26
    Electronic Resource
    Electronic Resource
    The relative insensitivity of Manduca sexta larvae to non-host plant secondary compounds (1990)
    Springer
    Entomologia experimentalis et applicata 54 (1990), S. 117-124 
    Details
    ISSN: 1570-7458
    Keywords: Antifeedant ; Manduca sexta ; host plant choice ; preference feeding behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Nous avons examiné au moyen des expériences de choix, les effects dissuasifs des composés secondaires de plantes non-hôtes des chenilles de M. sexta Johan. Des disques de fibres de verre ou des rondelles de feuilles de tabac ont été traités chimiquement, aux concentrations à peu près naturelles. Sur les 30 substances examinées sur les disques de fibres de verre, 6 ont été répulsives pour des chenilles élvées sur aliment artificiel. Quand l'examen est effectué avec des rondelles de feuilles de tabac, seul un produit est encore répulsif. Aucun effet répulsif n'est observé quand des chenilles élevées sur tabac sont mises en présence de substances associées à des rondelles de feuille de tabac. Ces résultats suggèrent que le maintien d'un spectre d'hôtes limité chez les chenilles de M. sexta ne repose pas sur l'évitement des plantes non-hôtes par suite de leurs substantes dissuasives, mais sur l'attraction et la stimulation provoquées par les hôtes.
    Notes: Abstract We tested the deterrent effects of non-host plant secondary compounds on Manduca sexta Johan. larvae, in choice tests. Treatment chemicals were applied, at approximately natural concentrations to either glass fiber or tobacco leaf disks. Of 30 compounds tested on glass fiber disks, with artificial diet reared larvae, 6 were deterrent. When the 6 deterrent chemicals were tested on tobacco leaf disks only one was still deterrent. No deterrent effects were observed when tobacco reared larvae were tested with chemicals applied to tobacco leaf disks. The results suggest that maintenance of restricted host range in M. sexta larvae relies not on avoidance of non-hosts due to deterrence but on attraction and stimulation to feed on hosts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00343520
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  • 27
    Electronic Resource
    Electronic Resource
    Effects of ingestion of some non-host plant secondary compounds on larvae of Manduca sexta (1990)
    Springer
    Entomologia experimentalis et applicata 54 (1990), S. 125-130 
    Details
    ISSN: 1570-7458
    Keywords: Manduca sexta ; deterrence ; toxicity ; oligophagy ; plant secondary compound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Les effets qui suivent l'ingestion de 7 produits secondaires de plantes non-hôtes ont été examinés sur des chenilles de M. sexta. Ces substances avaient été choisies pour la diversité de leurs effets sur le comportement alimentaire lors d'expériences de courte durée: 4 avaient montré des effets dissuasifs variés, 3 n'en avaient pas présenté. On a enduit des feuilles fraiches de leur plante-hôte (Nicotania tabacum) des différentes substances à raison d'à peu près 1% du poids sec. Seule une substance a réduit les performances des chenilles. Ces résultats ont été discutés en fonction de l'absence de relation entre dissuation et toxicité dans l'évolution des défenses chez les plantes.
    Notes: Abstract Seven non-host plant secondary compounds were tested for their post-ingestional effects on larvae of Manduca cesta Johan. The compounds were selected for their range of effects on feeding behavior in short-term tests: four showed different levels of deterrence while three were not deterrent. Insects were dosed by coating fresh leaves of their food plant (tobacco) with particular compounds at concentrations of 1% dry weight. Only one compound had detrimental effects on larval performance. The results are discussed in the context of the lack of correlation between deterrence and toxicity and the evolution of plant defenses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00343521
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  • 28
    Electronic Resource
    Electronic Resource
    Rutin: a phagostimulant for the polyphagous acridid Schistocerca americana (1991)
    Springer
    Entomologia experimentalis et applicata 60 (1991), S. 19-28 
    Details
    ISSN: 1570-7458
    Keywords: Schistocerca americana ; rutin ; grasshopper ; phagostimulant ; phenolic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rutin was demonstrated to be a phagostimulant for the grasshopper Schistocerca americana across a very wide concentration range. The effect was not maintained over a period of days if the insects had already ingested a large amount, but when individuals were given different concentrations on disks as supplements to their lettuce diet, they tended to self select a moderate quantity on a daily basis. In long term experiments on food utilization and growth rates using artificial diet, no beneficial effects of rutin could be demonstrated. Ingested rutin was absorbed and some of it deposited in the cuticle. Most was excreted as the aglycone quercetin. The possible functional significance of the phagostimulatory effect is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00164955
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  • 29
    Electronic Resource
    Electronic Resource
    Meal size in nymphs of Locusta migratoria (1972)
    Springer
    Entomologia experimentalis et applicata 15 (1972), S. 399-410 
    Details
    ISSN: 1570-7458
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Die Nahrungsmenge, die von einer Larve der Wanderheuschrecke, Locusta migratoria L., im fünften Entwicklungsstadium bei einer einzigen Mahlzeit verzehrt wird, wurde ermittelt, indem ihr Darm und Darminhalt sofort nach dem Fressen gewogen wurden. In der Mitte des Entwicklungsstadiums wurden größere Mengen verzehrt, Weibchen fraßen mehr als Männchen, jedoch sind die weiblichen Larven ja auch größer. Die Menge der aufgenommenen Nahrung vergrößerte sich mit der Dauer künstlichen Futterentzuges. Sie erreichte ihren Höhepunkt nach sechs Stunden, nach welcher Zeit der Vorderdarm absolut leer war. Die verzehrten Mengen waren je nach der Art der Nahrung unterschiedlich. Auch stellten die Insekten sich so ein, daß sie von einer bestimmten Nahrung mehr zu sich nahmen, wenn sie daran aufgezogen worden waren. Nach längeren Zeitspannen der Isolierung hatten sie die Tendenz, weniger zu fressen. Temperatur und Feuchtigkeit hatten keinen Einfluß auf die Mengen, die verzehrt wurden, außer bei 40°, bei welcher Temperatur sich das gesamte Verhalten zum Fressen ändert.
    Notes: Abstract Meal size in fifth-instar nymphs of Locusta migratoria L. has been investigated by weighing the gut and its contents immediately after feeding. Larger meals are taken in mid-instar, while females eat more in one meal than males under the same conditions. Bigger meals are also eaten after longer periods of food deprivation, but after deprivation for two hours or less, corresponding with the normal interfeed length, meals are smaller than would be expected from the potential maximum foregut volume. The maximum volume attained varies with the type of food available to the insects and is influenced by previous conditioning. Temperature and humidity do not affect meal size except at 40°, at which temperature the usual pattern of feeding is completely altered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00293604
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  • 30
    Electronic Resource
    Electronic Resource
    The effect of combinations of deterrents on the feeding behaviour of Locusta migratoria (1978)
    Springer
    Entomologia experimentalis et applicata 23 (1978), S. 101-109 
    Details
    ISSN: 1570-7458
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Dix substances provoquant l'inappétence, appartenant à sept classes chimiques différentes, ont été examinées isolément et en diverses combinaisons quant à leur effet sur Locusta migratoria. L'inappétence obtenue avec différentes combinaisons a indiqué que les effects des substances chimiques individuelles s'additionnaient. Un groupe de quatorze composés phénoliques dérivés des feuilles de sorgho a été éprouvé à des concentrations existant dans la nature. Bien que ces composés n'aient pas causé individuellement une inappétence mesurable, le mélange de tous les composés, aux mêmes concentrations, a réduit considérablement l'ingestion d'aliments.
    Notes: Abstract Combinations of feeding deterrents are additive in their effects on the feeding behaviour of Locusta migratoria. The effect has been shown within and across different chemical classes. A mixture of fourteen different phenolic compounds from Sorghum bicolor tested in naturally occurring concentrations is deterrent although the individual levels of deterrence are not measurable. The significance of the findings in relation to plant resistance is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00290624
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