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Sökning: WFRF:(Hellqvist Karin)

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  • Danielsson, M, et al. (författare)
  • Mini-seedlings of Picea abies are less attacked by Hylobius abietis than conventional ones : Is plant chemistry the explanation?
  • 2008
  • Ingår i: Scandinavian Journal of Forest Research. - 0282-7581. ; 23:4, s. 299-306
  • Tidskriftsartikel (refereegranskat)abstract
    • The pine weevil, Hylobius abietis (L.), is a major pest in conifer reforestation areas in the Palaearctic region. Size and chemistry of the seedlings may explain the damage rates in plantations. The performance of 10-week containerized seedlings (mini-seedlings) was compared with 1-year-old conventional seedlings of Norway spruce, Picea abies (L.), in a field experiment in central Sweden. After 2 years the weevil damage was lower for the mini-seedlings than for the conventional seedlings (3.5 vs 55%). After 3 years, the overall survival was 82 and 75%, respectively. Weevil damage was the main cause of mortality for conventional seedlings, whereas mini-seedlings mainly died from drought. Volatiles of the two seedling types were compared by solid-phase microextraction-gas chromatography -mass spectrometry (SPME-GC-MS). Unwounded mini-seedlings and conventional seedlings differed in their compositions of monoterpenes and sesquiterpenes. Miniseedlings mainly emitted limonene, known to be repellent to the pine weevil. When wounded, green leaf volatiles were released by mini-seedlings while the pine weevil attractant alpha-pinene was released by conventional seedlings. Volatiles may partly explain the mini-seedlings' resistance against weevil attack. Further studies are needed to clarify how long this miniseedling effect remains.
  • Sunnerheim, Kerstin, et al. (författare)
  • Quantitative structure-activity relationships of pine weevil antifeedants, a multivariate approach
  • 2007
  • Ingår i: Journal of Agricultural and Food Chemistry. - 0021-8561. ; 55:23, s. 9365-9372
  • Tidskriftsartikel (refereegranskat)abstract
    • Antifeedant activity of mainly phenylpropanoic, cinnamic, and benzoic acids esters was tested on the pine weevil, Hylobius abietis (L.). Of 105 compounds screened for activity, 9 phenylpropanoates, 3 cinnamates, and 4 benzoates were found to be highly active antifeedants. To understand the structure–activity relationships of these compounds, a multivariate analysis study was performed. A number of molecular and substituent descriptors were calculated and correlated to results from two-choice feeding tests with H. abietis. Three local models were developed that had good internal predictive ability. External test sets showed moderate predictivity. In general, low polarity, small size, and high lipophilicity were characteristics for compounds having good antifeedant activity.
  • Unelius, R., et al. (författare)
  • Structure-activity relationships of benzoic acid derivatives as antifeedants for the pine weevil, Hylobius abietis
  • 2006
  • Ingår i: Journal of Chemical Ecology. - 0098-0331. ; 32:10, s. 2191-2203
  • Tidskriftsartikel (refereegranskat)abstract
    • Aromatic organic compounds found in the feces of the pine weevil, Hylobius abietis (L.) (Coleoptera: Curculionidae), have been shown to deter feeding behavior in this species, which is a serious pest of planted conifer seedlings in Europe. We evaluated 55 benzoic acid derivatives and a few homologs as antifeedants for H. abietis. Structure-activity relationships were identified by bioassaying related compounds obtained by rational syntheses of functional group analogs and structural isomers. We identified five main criteria of efficiency as antifeedants among the benzoic acid derivatives. By predicting optimal structures for H. abietis antifeedants, we attempted to find a commercial antifeedant to protect conifer seedlings against damage by H. abietis in regenerating forests. New, highly effective antifeedants are methyl 2,4-dimethoxybenzoate, isopropyl 2,4-dimethoxybenzoate, methyl 2-hydroxy-3-methoxybenzoate, methyl (3,5-dimethoxyphenyl)acetate, and methyl (2,5-dimethoxyphenyl)acetate. Of these, methyl 2,4-dimethoxybenzoate and isopropyl 2,4-dimethoxybenzoate have the highest antifeedant indices of all substances tested and are the best candidates for practical applications in order to protect planted seedlings in the field.
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