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  • 1
    ISSN: 1432-1939
    Keywords: Heliothis zea ; Cytochrome P-450 ; Induced tolerance ; Allelochemicals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Incubation of Heliothis zea (Boddie) eggs on foliage of Lycopersicon hirsutum f. glabratum C.H. Mull (accession PI 134417) results in neonates with elevated levels of tolerance to the toxic effects of PI 134417 foliage attributable to 2-tridecanone found in the glandular trichomes which abound on that foliage. The neonates from such eggs are also shown to have elevated levels of tolerance to the carbamate insecticide carbaryl. Incubation of eggs in an atmosphere containing 2-tridecanone similarly produced elevated levels of tolerance to 2-tridecanone among resulting neonates, indicating that 2-tridecanone is the likely inducing agent and that exposure to 2-tridecanone vapor, which is known to emanate from PI 134417 foliage, is sufficient for induction. Analysis of the cytochrome P-450 content in gut microsomes of fifth instar larvae indicated that exposure of larvae to 2-tridecanone in artificial diet or to PI 134417 foliage resulted in significantly elevated levels of cytochrome P-450 relative to larvae fed diet without 2-tridecanone or foliage of L. esculentum which contains no 2-tridecanone. In addition, removal of the glandular trichomes from PI 134417 foliage eliminated the ability of that foliage to induce elevated levels of cytochrome P-450. These results provide circumstantial evidence that cytochrome P-450 may be involved in the induced tolerance to xenobiotics among neonates from eggs exposed to 2-tridecanone or PI 134417 foliage.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 60 (1991), S. 289-300 
    ISSN: 1570-7458
    Keywords: Host-plant resistance ; host-plant suitability ; fertilizer ; M. sexta ; H. zea ; L. decemlineata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of fertilizer regime on trichome- and lamellar-based resistance in the wild tomato species, Lycopersicon hirsutum f. glabratum C.H. Mull accession PI 134417, to three insect pests of tomato, the tobacco hornworm, Manduca sexta (L.), the colorado potato beetle, Leptinotarsa decemlineata (Say), and the tomato fruitworm, Heliocoverpa zea (Boddie), was examined. Increasing the rate at which NPK fertilizer was applied, from 1.8 to 19.6 g/plant/week, reduced the trichome-based resistance of PI 134417 to M. sexta and L. decemlineata by lowering both the density of type VI (sensu Luckwill, 1943) glandular trichomes and the amount of 2-tridecanone contained in the tips of these trichomes. 2-Tridecanone is a toxic methyl-ketone responsible for glandular trichome-mediated resistance in PI 134417 to M. sexta and L. decemlineata. A similar increase in the application rate of NPK fertilizer reduced the lamellarbased resistance of PI 134417 to L. decemlineata and H. zea. The meachanisms for this reduction of resistance are unknown, but may be related to improved nutritional quality of hosts at higher fertilizer regimes.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 58 (1991), S. 1-14 
    ISSN: 1570-7458
    Keywords: Host-plant resistance ; predators ; parasites ; herbivore adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Des modèles conceptuels et mathématiques ont servi à examiner l'influence du potentiel d'ennemis naturels sur le taux d'adaptation d'herbivores à des facteurs de résistance des plantes. Les résultats montrent que les ennemis naturels peuvent augmenter ou réduire le taux d'adaptation des herbivores. Les effets spécifiques (comportementaux et physiologiques) d'un facteur de résistance sur l'herbivore, aussi bien que le comportement de l'ennemi naturel et la dynamique de population du système ennemi naturel/herbivore permettent de déterminer le niveau de l'effet des ennemis naturels sur le taux d'adaptation de l'herbivore au facteur de résistance. Une adaptation de l'herbivore à une résistance partielle à une plante est généralement envisagée comme plus lente qu'une adaptation à des hauts niveaux de résistance, même en présence d'ennemis naturels, mais il peut y avoir des exceptions.
    Notes: Abstract The potential of natural enemies to influence the rate of herbivore adaptation to resistance factors in plants is examined using conceptual and mathematical models. Results indicate that natural enemies could increase or decrease the rate of herbivore adaptation. The specific behavioral and physiological effects of a resistance factor on the herbivore, as well as the behavior of the natural enemy, and the population dynamics of the natural enemy/herbivore system are important in assessing the extent to which the natural enemies will affect the rate of herbivore adaptation to a resistance factor. Herbivore adaptation to partial resistance in a host-plant is generally expected to be slower than adaptation to high levels of resistance, even in the presence of natural enemies, if genetic variance is not limiting.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1570-7458
    Keywords: Lycopersicon hirsutum f.glabratum ; Lycopersicon esculentum ; Leptinotarsa decemlineata ; Heliothis zea ; glandular trichomes ; leaf lamellar-based resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé La tomate sauvage,L. hirsutum f.glabratum C.H. Mull, n0 PI134417, présente des lamelles foliaires qui lui confèrent une résistance au doryphore,L. decemlineata Say et àH. zea Bodie. Cette étude a voulu préciser si ces résistances étaient héritées ensemble dans des populations d'hybrides entre PI 134417 et la tomate cultivée,L. esculentum Mill. Des lignées de plantes présentant une gamme de résistance àH. zea ont été sélectionnées à partir d'une population hyrbide. De même, des lignées de plantes ayant une gamme de résistance àL. decemlineata ont été sélectionnées à partir d'un second groupe d'hybrides. Les réactions des 2 insectes aux 2 groupes de plantes ont été estimées. Les résistances àH. zea et àL. decemlineata n'étaient pas corrélées nettement. Certaines lignées sont résistantes aux 2 espèces, mais d'autres ne sont résistantes qu'à une espèce. Ainsi, les résistances à chacune de ces espèces ont probablement des déterminismes génétiques différents. Différentes composantes mécaniques sont vraisemblablement impliquées dans ces résistances, bien qu'il soit possible qu'au moins quelques facteurs aient un rôle important dans le conditionnement de la résistance. La création de cultivars de tomates avec une résistance liée aux lamelles foliaires sera compliquée par le besoin d'une sélection en fonction des réponses aux 2 espèces..
    Notes: Abstract Segregating populations of hybrids of the insect-resistant wild tomato,Lycopersicon hirsutum f.glabratum, C.H. Mull, PI 134417, and the susceptible tomato cultivar ofL. esculentum Mill, ‘Walter’, were screened by bioassays with the Colorado potato beetle,Leptinotarsa decemlineata (Say) and tomato fruitwormHeliothis zea (Boddie). Plant lines with a range of levels of resistance toH. zea were selected from one group of hybrids; plants with a range of resistance levels toL. decemlineata, from another group. The response of both insect species to both groups of plants was evaluated. Resistance to each of these species is under separate genetic control and apparently involves distinct mechanistic components, although it remains possible that at least some factors are important in conditioning resistance to both species.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 17 (1991), S. 989-1005 
    ISSN: 1573-1561
    Keywords: Host-plant resistance ; host-plant selection ; glycoalkaioids ; Leptinotarsa decemlineata ; Coleoptera ; Chrysomelidae ; Lycopersicon ; α-tomatine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The role of the steroidal glycoalkaloid α-tomatine in the hostplant resistance of tomato to the Colorado potato beetle,Leptinotarsa decemlineata (Say) was examined in short- (24 hr; using first- and fourth-instar larvae) and long-term (first-instar larvae reared through the prepupal stage) feeding experiments. Consumption rate, growth rate, efficiency of conversion of ingested food to body mass, and survival were compared forL. decemlineata provided foliage from susceptible (Lycopersicon esculetum Mill. cv. Walter), resistant (L. hirsutum f.Glabratum C.H. Mull accession PI 134417), and F1 hybrid plants. Values obtained for dietetic indices were regressed against corresponding values for α-tomatine content of foliage provided to larvae. Differences in dietetic indices could not be attributed to variation in foliar α-tomatine content despite a long-standing literature showing theex planta α-tomatine inhibits feeding and growth byL. decemlineata.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-1561
    Keywords: Campoletis sonorensis ; Hymenoptera ; Ichneumonidae ; Heliothis zea ; Lepidoptera ; Noctuidae ; 2-tridecanone ; trichomes ; Lycopersicon hirsutum f.glabratum ; tomato ; plant defense ; allelochemical
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Greenhouse-grown plants of five tomato lines varying in their level of 2-tridecanone-mediated resistance toManduca sexta (L.) andLeptinotarsa decemlineata (Say) were found to adversely affect larvae ofCampoletis sonorensis (Cameron), a larval endoparasitoid ofHeliothis zea (Boddie), in a manner directly related to their level of resistance. The parasitoid larvae, which emerge as fifth instars from their host and construct a cocoon on the foliage of their hosts' host plant, suffered extensive mortality during cocoon spinning on highly resistant foliage. Mortality was greatest (82%) on the highly resistant plants ofLycopersicon hirsutum f.glabratum (accession PI 134417) and an F1 backcross [(L. esculentum × PI 134417) × PI 134417] selection. Mortality was intermediate (40 and 28%, respectively) on backcross selections with moderate and low levels of resistance and least (8%) on susceptibleL. esculentum. Removal of the glandular trichomes, which contain 2-tridecanone in their tips, from the foliage eliminated differences in parasitoid mortality among plant lines. Bioassays of 2-tridecanone indicated that it is acutely toxic to fifth instarC. sonorensis larvae at the quantities associated with highly resistant foliage and produces symptoms identical to those observed on resistant foliage. 2-Undecanone, a second methyl ketone present in the glandular trichomes of resistant foliage, was also toxic toC. sonorensis larvae, but significantly less so than 2-tridecanone. The results support the hypothesis that 2-tridecanone is responsible for the observed mortality ofC. sonorensis larvae during cocoon construction on resistant foliage.
    Type of Medium: Electronic Resource
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