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  • 1
    ISSN: 1432-1939
    Keywords: Iridomyrmex humilis ; Predation ; Host range ; Prey acceptability ; Lepidoptera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Experiments are described which test the hypothesis that more host-specific species of caterpillars should be less aceptable to a generalist predator than polyphagous species. Caterpillars of all species were tested in paired choice tests with the Argentine ant, Iridomyrmex humilis. Experiments were replicated ten times, videotaped and later analyzed. Brightly colored specialist species (normally considered to be aposematic) were clearly the least palatable, while more cryptic specialists were also significantly less acceptable than generalists overall. Leaf-tying species were considered separately; all were highly palatable independent of host range. The results indicate that among caterpillars that do not construct leaf shelters, those with a wide post range are more acceptable than those with a narrow host range. This is consistent with the notion that generalist predators provide selection pressure favoring narrow host range in their herbivorous prey.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 78 (1996), S. 1-8 
    ISSN: 1570-7458
    Keywords: induction ; imprinting ; learning ; caterpillar ; Lepidoptera ; experience ; diet breadth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This review discusses the ambiguity of results obtained from dual-choice feeding tests, especially in relation to the study of effects of experience. Induced preference experiments done this way can be caused by up to nine potential changes in caterpillar behavior. In addition different physiological mechanisms that could lead to the process of induced preference are discussed. These include habituation to deterrents, the increased ability to process xenobiotics, the acquisition of specific positive responses, sensitization, and associative learning. These different processes might relate to function in different ways so that distinguishing them is important to progress in understanding the phenomenon. Suggestions for experimental designs that provide details on processes involved are indicated.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 64 (1992), S. 289-292 
    ISSN: 1570-7458
    Keywords: Deterrence ; oral dosing ; toxicity ; diet breadth ; Hypera brunneipennis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A variety of plant secondary compounds, several of which are quite widespread in nature were tested for their deterrence to the specialist coleopteran Hypera brunneipennis (Boheman) in short-term behavioral assays. The compounds were nicotine, quinine, sparteine, hordenine, linamarin, amygdalin, sinigrin, morin, juglone, chlorogenic acid, digitonin, mimosine, diosgenin, rutin and ursolic acid. Nine of these were then tested for their post-ingestional effects over one to two weeks of adult life, using fecundity as a measure of the effects. In only one case was there any indication of a detrimental effect or any trend suggesting one. The evolutionary implications of these findings are discussed.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1572-8889
    Keywords: Iridomyrmex humilis ; predation ; chemical defense ; nicotine ; Lepidoptera ; plant/insect interactions ; herbivore
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Experiments were performed to test the acceptability of two palatable, cryptic caterpillars, the tobacco hornworm,Manduca sexta, and the cabbage looper,Trichoplusia ni, reared on different diets, to the Argentine ant,Iridomyrmex humilis. Ants preferred larvae reared on artificial diet, groundcherry, or cowpea to tobacco-reared larvae. Ants also preferred larvae reared on artificial diet without nicotine to larvae reared on diet containing nicotine (5% dry wt). Experiments were also performed to test the response of ants to larval extracts and chemicals applied to the surface of palatable prey. Ants did not respond differently to larvae of the potato tuber moth,Phthorimaea operculella, treated with larval extracts or regurgitate from tobacco-reared larvae compared to artificialdiet-reared larvae, but ants were deterred byP. operculella larvae treated with nicotine compared to untreated larvae. The results of this study indicate that caterpillars can derive at least some degree of chemical protection from their food plant without sequestering and storing plant compounds and without the development of elaborate aposematic characteristics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 46 (1988), S. 241-247 
    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
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 52 (1989), S. 119-133 
    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
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 54 (1990), S. 125-130 
    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
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  • 8
    ISSN: 1573-1561
    Keywords: Tannins ; digestibility-reducing substances ; surfactants ; detergency ; herbivory ; chemical defense ; allelochemics ; Manduca sexta ; Lepidoptera ; Sphingidae ; Schistocerca gregaria ; Orthoptera ; Acrididae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The rate of hydrolysis of the abundant foliar protein, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPC), in enzymatically active gut fluid ofManduca sexta larvae is very rapid and is unaffected by the presence of tannic acid, even when tannic acid is present in the incubation mixture in amounts in excess of the amount of RuBPC. When this protein is dissolved in the denatured gut fluids ofM. sexta larvae orSchistocerca gregaria nymphs, large amounts of tannic acid must be added to bring about the precipitation of significant quantities of protein. The ability of insect gut fluid to prevent the formation of insoluble tannin-protein complexes is due to the presence of surfactants. On the basis of our results and a review of the findings of other investigators, we argue that there is no evidence that tannins reduce the nutritional value of an insect's food by inhibiting digestive enzymes or by reducing the digestibility of ingested proteins and, further, that the failure of tannins to interfere with digestion is readily explained on the basis of well-documented characteristics of the digestive systems of herbivorous insects. In challenging the currently popular notion that tannins are digestibility-reducing substances, we do not challenge the general utility of either the apparency theory or resource availability theory of plant defense. In debating the merits of these two analyses of plant-herbivore interactions, however, the demise of tannins as all-purpose, dose-dependent, digestibility-reducing defensive substances must be taken into account.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-1561
    Keywords: Lepidoptera ; Hymenoptera ; predation ; sequestration ; chemical ; defense ; cuticle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Larvae ofUresiphita reversalis (Guenée) (Lepidoptera: Pyralidae) sequester quinolizidine alkaloids from their leguminous hosts and store them primarily in the cuticle. Stored alkaloids are lost with the last larval molt. Extracts of late-instar larvae and of pupae were applied to larvae of the potato tuber moth,Phthorimaea operculella (Zeller) (Gelichiidae), which are normally palatable to two hymenopteran predators, the Argentine ant,Iridomyrmex humilis (Mayr) (Formicidae), and the paper wasp,Mischocyttarus flavitarsus (Sauss.) (Vespidae). Larvae ofP. operculella treated with alkaloid extracts ofU. reversalis larval exuviae, or with surface extracts of whole larvae, were deterrent to both predators, compared to untreated prey. Extracts of pupal exuviae added toP. operculella, however, were not deterrent.P. operculella larvae treated with the authentic alkaloids sparteine and cytisine were also deterrent to these hymenopteran predators. Storage of small but concentrated amounts of plant secondary compounds in the cuticle appears to be an efficacious means of defense against at least two common predators of lepidopteran larvae.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1573-1561
    Keywords: Uresiphita reversalis ; Lepidoptera ; Pyralidae ; Genista ; French broom ; quinolizidine alkaloids ; sequestration ; aposematism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Larvae ofUresiphita reversalis feed almost exclusively on legumes in the tribe Genisteae, which characteristically contain a variety of quinolizidine alkaloids. The larvae are aposematic, and onGenista monspessulana, a major host in California, they feed on the youngest leaves, at the periphery of the plant. These leaves, which were preferred over older foliage in choice tests, contained four to five times the level of alkaloid found in older leaves. The major alkaloids detected in these plants were dehydroaphylline andN-methylcytisine, together accounting for 74% of the total. Preliminary analyses showed the alkaloid profile of exuviae from larvae feeding on these plants was very similar to that of the plants. Two alkaloids, sparteine and cytisine, which are known components of some hosts ofU. reversalis, were phagostimulants for fifth-instar larvae when added to sucrose-impregnated glass-fiber disks. In addition, when sparteine was added to foliage ofG. monspessulana, effectively doubling the percent dry weight of alkaloid, the growth rate of late-instar larvae was positively affected. Cytisine added to plants had no discernible effect on growth of larvae. Alkaloid levels in larvae and in their frass were proportional to levels in the plants on which they fed. Although the majority of alkaloid was excreted, that which was sequestered by the insect was found entirely in the integument, possibly confering some protection from predators.
    Type of Medium: Electronic Resource
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