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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 17 (1991), S. 1107-1121 
    ISSN: 1573-1561
    Keywords: Tobacco budworm ; Heliothis virescens ; Lepidoptera ; Noctuidae ; cotton ; Gossypium hirsutum ; plant resistance ; plant-insect interaction ; terpenoids ; gossypol ; allelochemicals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Female moths of the tobacco budworm,Heliothis virescens (F.), oviposit in the terminals of the cotton plant,Gossypium hirsutum (L.). The hatched larvae migrate to the terminal area and then to small squares (buds), on which they feed, finally burrowing into the anthers where they grow and develop. They attempt to avoid gossypol glands as they feed. Chemically related evidence explains, in part, these observations. The calyx crown of resistant lines (which is avoided) is high in the terpenoid aldehydes (TAs) including gossypol. HPLC data showed that the gossypol content of both susceptible and resistant glanded lines is equal, while the hemigossypolone and heliocides H1 and H2 are greatly increased in resistant lines and presumably are more closely associated with resistance. Analysis for total amino acids in cotton square tissues showed that there was a gradation from the calyx and calyx crown, which were lowest, to the anthers, the site of final insect development, which were highest. Synthetic diets mimicking amino acid distribution in anthers were found to be successful for larval growth and development.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-1561
    Keywords: Cotton ; Gossypium arboreum ; tobacco budworm ; Heliothis virescens ; Lepidoptera ; Noctuidae ; resistance ; allelochemicals ; flavonoids ; gossypetin 8-0-rhamnoside ; gossypetin 8-0-glucoside
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Asiatic cottons [Gossypium arboreum (L.)] have been investigated as a source of resistance to the tobacco budworm [Heliothis virescens (Fab.)] because their diversely colored petals have been presumed to contain various allelochemicals. However, we found that larvae fedG. arboreum squares (buds) grew about equally compared with those fed squares from commercialG. hirsutum lines. The best source of resistance was found in severalG. hirsutum double-haploid (DH) lines. In our investigation of allelochemicals, G.arboreum lines were found to contain much less gossypol in leaves, squares (buds), and petals thanG. hirsutum L. lines. Flavonoids were significantly higher inG. arboreum lines only in petals. Of 22G. arboreum lines from which squares were gathered and fed to tobacco budworm (TBW) larvae in the laboratory, larval growth was not significantly decreased on any, but larval survival was decreased on six. When the square flavonoids were isolated and incorporated in laboratory diets for the TBW, moderate toxicity was observed. However, the estimated toxicities were not greater than those of the same flavonoid isolates fromG. hirsutum lines. The most prevalent flavonoids, all previously found in G.arboreum plant tissues, were gossypetin 8-0-glucoside and gossypetin 8-0-rhamnoside, neither of which were present inG. hirsutum tissue. Quercetin 3-0-glucoside, quercetin-3′-0-glucoside, and quercetin 7-0-glucoside were also present in significant amounts in both species. Gossypetin 8-0-rhamnoside and gossypetin 8-0-glucoside were the most toxic flavonoids tested (the ED50% was estimated to be 0.007 and 0.024) and therefore may prove to be contributing factors of resistance to TBW feeding.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-1561
    Keywords: Corn ; Zea mays (L.) ; fall armyworm ; Spodoptera frugiperda (J. E. Smith) ; Lepidoptera ; feeding resistance ; hemicellulose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The fall armyworm,Spodoptera frugiperda (J. E. Smith), (FAW) is a major pest of corn,Zea mays L., in the southeastern United States. The damage to pretassel corn is caused by larvae feeding primarily on immature inner whorls. In this study, resistant lines were found to contain more crude fiber in whorls, mostly hemicellulose and cellulose. While hemicellulose, chiefly an arabinoxylan, was higher in resistant (R) lines than in susceptible (S) lines, the distribution of constituent neutral sugars was very similar in the lines. Both lines also containedp-coumaric and ferulic acids. These phenolic acids are known to occur both in the free state and in the cell wall as complexes bound by ester linkages to the arabinose moiety of the arabinoxylan.13C NMR data showed that the intensity of the carbonyl carbon (184 ppm) in resistant hemicellulose was stronger, indicating a greater degree of cross-linking. Thus, resistant hemicellulose is both structurally different from susceptible hemicellulose and present in greater quantities. In two of three laboratory dietary tests, FAW larval weight gains were significantly higher on diets with (S) hemicellulose incorporated at the same level as (R) hemicellulose. Therefore, resistance to the FAW appears to be correlated with both a greater amount and a higher degree of cross-linking of the hemicellulose of (R) lines.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 10 (1984), S. 311-320 
    ISSN: 1573-1561
    Keywords: Gypsy moth ; Lymantria dispar ; Lepidoptera ; Lymantriidae ; Blepharipa pratensis ; Diptera ; Tachinidae ; host selection ; contact chemical ; parasite behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The host selection process ofBlepharipa pratensis (Meigen), a tachinid parasite of the gypsy moth,Lymantria dispar L., was investigated. Once in the host's habitat, and following contact with a recently damaged leaf edge (cut, torn, eaten), the fly orients perpendicular to the edge and moves back and forth with the front tarsi grasping the damaged edge. Oviposturing (oviposition intention) may occur. Leaf exudates appear to arrest the fly on the leaf and increase tarsal examination (searching). If an edge of a gypsy moth-eaten leaf is contacted, oviposition usually occurs. Significantly more eggs are laid when host-browsed foliage is encountered, compared to mechanically cut or damaged foliage, indicating response to a cue left by the host during feeding. The number of host-damaged leaf clusters in an area significantly enhances oviposition there; in field-cage tests, significantly more eggs (7911) were laid in simulated-crown areas with all clusters browsed, compared to the adjacent areas containing 1/2 browsed (4200 eggs) and undamaged clusters (2209 eggs). A host selection sequence is suggested and discussed.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-1561
    Keywords: Corn ; Zea mays (L.) ; southwestern bora borer ; Diatraea grandiosella ; Dyar ; Lepidoptera ; Pyralidae ; feeding resistance ; 2-hydroxy-4,7-dimethoxy-1,4-benzoxazin-3-one ; N-O-Me-DIMBOA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The southwestern corn borer (SWCB),Diatraea grandiosella Dyar, is a major pest of corn,Zea mays L., in the southern United States. The damage to corn is caused primarily by larval feeding on leaf, ear, and stem tissues. In this study, 2-hydroxy-4,7-dimethoxy-1,4-benzoxazin-3-one (N-O-Me-DIMBOA) was identified by MS and NMR as present in corn whorl surface waxes. This compound has evidently not been isolated previously, but its glucoside has been reported in corn, wheat, andCoix lachryma. It is present in the waxes in a higher concentration than DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one) and 6-MBOA (6-methoxybenzoxazolinone). It was toxic to the SWCB in a stress diet, but it was less toxic to this insect than 6-MBOA when incorporated in the standard rearing diet. Nevertheless, it may have some role in the resistance of corn to the SWCB because the total surface wax content is higher in resistant lines than in susceptible lines.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-1561
    Keywords: Fall armyworm ; Spodoptera frugiperda ; Lepidoptera ; Noctuidae ; corn ; Zea mays ; plant-insect interaction ; amino acids ; herbivory ; feeding resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The free amino acids have been shown by isolational work and choice bioassays to be more important than all other factors evaluated in defining leaf-feeding resistance of corn (Zea mays L.) to fall armyworm (FAW) [(Spodoptera frugiperda J.E. Smith)] larvae. 6-MBOA (6-methoxybenzoxazolinone) and maysin, toxins present in corn, were shown not to be significant factors for leaf-feeding resistance to first-instar FAW larvae because of their low concentrations in the whorl. Amino acid analysis showed that while the ratios of the essential amino acids in susceptible (S) and resistant (R) lines were similar, there were differences in the nonessential amino acids, particularly aspartic acid, which was higher in R lines. Also, the ratio of essential amino acids to nonessential amino acids was important, being too low in expressed whorl leaf juice (obtained from V8–V10 growth stage plants) to support larval growth, although juice was stimulatory in choice tests. The total protein content of whorls in S lines was about 15% higher than in R lines, but the significance of this difference is uncertain, because nutritional tests showed that larval growth increased with total protein only up to 12% protein. Sugars were only slightly stimulatory. Thus, the amino acids along with higher hemicellulose content of R lines, established by us earlier, appear to explain much of the basis of resistance in corn to larval leaf-feeding of the FAW.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-1561
    Keywords: Southwestern corn borer ; Diatraea grandiosella Dyar ; Lepidoptera ; Pyralidae ; corn ; Zea mays L. ; plant-insect interaction ; amino acids ; sugars ; herbivory ; feeding resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The leaf-feeding resistance of corn or maizeZea mays L. to the southwestern corn borer, SWCB,Diatraea grandiosella Dyar has been attributed at least in part to decreased protein, increased crude fiber, and increased hemicellulose in the whorls of resistant genotypes. In this study, individual amino acids and sugars were evaluated as arrestants, with the objective of identifying those that gave weak or negative responses. Several structure-activity relationships were identified. Larvae responded to three-carbonn alkyl alpha amino acids more than to two-, four-, five-, and six-carbon compounds. Amino acids with terminal isopropyl functions gave decreased responses relative to theirn-alkyl counterparts. Dicarboxylic acids and their amides gave the lowest responses of all classes of amino acids. The normally occurring basic amino acids were all good arrestants. The guanido [HN:C(NH2)NH-] function was somewhat important to an arrestant response, as was the number of methylenes between the alpha and omega amino functions of diaminon-alkyl amino acids. Hydroxy amino acids were generally good arrestants unless the hydroxyl was located on a ring system. The two sugars present in expressed corn whorl juice, glucose and fructose, gave poor responses. However, two other sugars, mannose and arabinose, whose C-2 hydroxyls are conformationally in the axial position, were strongly arrestant. Formulated amino acid mixtures based on their content in whorl juice were as strong arrestants as whorl juice. However, the relative contributions of amino acids and sugars that are weak arrestants to the resistance of corn to SWCB larvae is uncertain because amino acid analyses did not reveal significantly higher contents of these amino acids in the whorl juices of resistant lines.
    Type of Medium: Electronic Resource
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