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Prasantha B.D.R.,University of Peradeniya | Reichmuth C.,Institute for Ecological Chemistry | Adler C.,Institute for Ecological Chemistry | Felgentreu D.,Institute for Ecological Chemistry
Journal of Stored Products Research | Year: 2015

Newly emerged females of the cowpea weevil Callosobruchus maculatus (F.) and bean weevil Acanthoscelides obtectus (Say) were exposed to diatomaceous earth (DE). The cuticular water loss rate (μg cm-2 h-1) of the DE treated and untreated weevils was determined gravimetrically based on the total body mass changed at 25 ± 1 °C and 75 ± 5% r.h. within a 48 h period. Fatty acid profiles comprising acids with a carbon chain length between 9 and 20 carbon atoms (C9-C20) of C. maculatus (F.) and A. obtectus (Say) were studied comparatively by using extracted DE particles from DE treated weevils, pure DE, water extraction and hexane extraction of the weevils. Peak area percentages of the GC chromatograms were used to compare the cuticular lipid compositions. The cuticular water loss rate (CWLR) of DE treated weevils was significantly higher than that untreated weevils. Despite of the DE treated weevils strive to control their CWLR within the first 10-12 h, CWLR drop significantly until their physical death. DE and hexane extracts contained only fatty acid chain lengths between C16 and C18. The major fatty acid identified in the DE extracts was oleic acid in the C18:1cis9 group which averaged to about 55.7 ± 3.04% and 63.8 ± 3.52% in C. maculatus and A. obtectus, respectively. Hexane extracts showed that cuticular hydrocarbons of the C. maculatus were dominated by C18:2cis9,12 and C16:0 equivalents to the fatty acids of linoleic and palmitic acids, respectively. The loss of these fatty acids due to adsorption of DE may result in a greater water permeability of the insect cuticle and thus lead to desiccation and mortality. © 2015 Elsevier Ltd.


Ulrich D.,Institute for Ecological Chemistry | Nothnagel T.,Julius Kuhn Institute | Dunemann F.,Julius Kuhn Institute
Acta Horticulturae | Year: 2012

The totality of the sensory characteristics (appearance, smell, aroma, taste and mouthfeeling) of food influences the decision to buy fruit and vegetables to a greater or lesser extent. There is a good deal of evidence that the sensory characteristics "taste" and "aroma" have a very specific effect on the consumers' food choice. Therefore high sensory quality is not only a question of enjoyment value but also an important aspect of healthy nutrition. In the present paper an example of a reliable non-targeted approach for aroma assessment is demonstrated. The developed method is a combination of an effective sample preparation and a non-targeted data processing. It consists of automated headspace solid phase microextraction (HS-SPME), gas chromatography (with FID or MS detector) and data processing by pattern recognition. The analysis approach is used in plant genetics, practical breeding programs as well as tool for quality assessment. The aroma patterns of carrots and apples were determined effectively by this kind of rapid, non-targeted analyses, and used for subsequent genetic and molecular investigations.


Ulrich D.,Institute for Ecological Chemistry | Nothnagel T.,Julius Kuhn Institute | Schulz H.,Institute for Ecological Chemistry
Journal of Agricultural and Food Chemistry | Year: 2015

The focus of the present work centers on the diversity of volatile patterns of carrots. In total 15 main volatiles were semiquantified in leaves and roots using isolation by headspace solid phase microextraction followed by gas chromatography with FID and MS detection. Significant differences in the main number of compounds were detected between the cultivars as well as the years. Genotype-environment interactions (G x E) are discussed. The most abundant metabolites, β-myrcene (leaves) and terpinolene (roots), differ in the sum of all interactions (cultivar x harvest year) by a factor of 22 and 62, respectively. A statistical test indicates significant metabolic differences between cultivars for nine volatiles in leaves and 10 in roots. In contrast to others the volatiles α-pinene, γ-terpinene, limonene, and myristicine in leaves as well as β-pinene, humulene, and bornyl acetate in roots are relatively stable over years. A correlation analysis shows no strict clustering regarding root color. While the biosynthesis in leaves and roots is independent between these two organs for nine of the 15 volatiles, a significant correlation of the myristicine content between leaves and roots was determined, which suggests the use of this compound as a bitter marker in carrot breeding. © 2015 American Chemical Society.


Ulrich D.,Institute for Ecological Chemistry | Bruchmuller T.,Julius Kuhn Institute | Kruger H.,Institute for Ecological Chemistry | Marthe F.,Julius Kuhn Institute
Journal of Agricultural and Food Chemistry | Year: 2011

Sixteen different genotypes of parsley, including two cultivars, six populations, and eight inbred lines, were investigated regarding their sensory characteristics in relation to the volatile patterns and resistance to Septoria petroselini. The sensory quality was determined by a combination of profile analysis and preference test, whereas the volatile patterns were analyzed by headspace-SPME-GC of leaf homogenates with subsequent nontargeted data processing to prevent a possible overlooking of volatile compounds. The more resistant genotypes are characterized by several negative sensory characteristics such as bitter, grassy, herbaceous, pungent, chemical, and harsh. In contrast, the contents of some volatile compounds correlate highly and significantly either with resistance (e.g., hexanal and α-copaene) or with susceptibility (e.g., p-menthenol). Some of these compounds with very strong correlation to resistance are still unidentified and are presumed to act as resistance markers. © 2011 American Chemical Society.


Nothnagel T.,Julius Kuhn Institute | Kramer R.,Julius Kuhn Institute | Budahn H.,Julius Kuhn Institute | Schrader O.,Julius Kuhn Institute | And 2 more authors.
Acta Horticulturae | Year: 2012

An interspecific crossing program was carried out to improve the genetic basis of garden asparagus (Asparagus officinalis L.) for resistance to biotic and abiotic stress as well as quality associated compounds. Currently, interspecific hybrids between Asparagus officinalis and A. amarus, A. maritimus, A. verticillatus as well as A. trichophyllus were generated by hand pollination and embryo rescue. In vivo established hybrid plants were analyzed using molecular and cytological techniques. The morphological characterization and chemical investigation of volatile compounds of the hybrids suggests an intermediate stage between the cross parents. Partially, the hybrids expressed a number of novel volatile compounds. Potential breeding value of the obtained interspecific hybrids and the further work is discussed.


Nothnagel T.,Institute for Breeding Research on Horticultural and Fruit Crops | Kramer R.,Institute for Breeding Research on Horticultural and Fruit Crops | Budahn H.,Institute for Breeding Research on Horticultural and Fruit Crops | Schrader O.,Institute for Breeding Research on Horticultural and Fruit Crops | And 3 more authors.
Acta Horticulturae | Year: 2012

The paper reports preliminary results of a research project aiming to improve the genetic basis of garden asparagus (Asparagus officinalis L.) for resistance to biotic and abiotic stress as well as quality associated compounds via interspecific and intersubspecific crosses. In the present study, interspecific hybrids between A. albus × A. officinalis, A. maritimus × A. officinalis, A. officinalis × A. verticillatus and A. amarus × A. verticillatus were generated by hand pollination and embryo rescue. The F1 hybrids were analyzed by using molecular and cytological techniques. Whereas the A. albus × A. officinalis hybrid was triploid, the three other hybrids were tetraploid. The morphological characterisation as well as chemical investigation of volatile compounds of the hybrids suggests an intermediate stage between the cross parents. Additionally, the hybrids expressed a number of novel volatile compounds. Potential value of the obtained interspecific hybrids and the further work is discussed.


Furstenau B.,Free University of Berlin | Adler C.,Institute for Ecological Chemistry | Schulz H.,Institute for Ecological Chemistry | Hilker M.,Free University of Berlin
Chemical Senses | Year: 2016

Host foraging of parasitic wasps attacking insects living in stored food may be guided by volatile cues emanating from these postharvest products. However, little knowledge is available as to how habitat odor released from noninfested stored food affects the parasitoid's response to host-specific chemicals. In this study, we investigated the impact of wheat grist odor on the olfactory host search by the ectoparasitoid Holepyris sylvanidis. This parasitoid attacks larvae of the confused flour beetle Tribolium confusum, a common pest of grain products. Olfactometer bioassays showed that female H. sylvanidis were attracted by volatiles released from host larval feces, whereas odor of noninfested wheat grist was neither attractive nor did it mask the host-indicating cues. We analyzed the odor of host larval feces and wheat grist by coupled gaschromatography-mass spectrometry and recorded the parasitoid's electroantennographic (EAG) responses to the detected volatiles. Two specifically host-associated components of the fecal odor, (E)-2-nonenal and 1-pentadecene, elicited strong EAG responses. Both components were attractive when tested individually, but less than larval feces. Attraction of parasitoids to these host-specific key compounds was enhanced by addition of (i) noninfested habitat substrate odor or (ii) a blend of 3 EAG-active (but not behaviorally active) volatiles that had been identified in odor of noninfested grist (benzaldehyde, 1-tetradecene, 1-hexadecene), but were also detected in the host fecal odor. The impact of these volatiles ubiquitously released in a food store by noninfested habitat substrate on the parasitoid's orientation to host-specific volatile cues is discussed. © The Author 2016. Published by Oxford University Press. All rights reserved.


PubMed | Institute for Ecological Chemistry
Type: Journal Article | Journal: Journal of agricultural and food chemistry | Year: 2011

Sixteen different genotypes of parsley, including two cultivars, six populations, and eight inbred lines, were investigated regarding their sensory characteristics in relation to the volatile patterns and resistance to Septoria petroselini . The sensory quality was determined by a combination of profile analysis and preference test, whereas the volatile patterns were analyzed by headspace-SPME-GC of leaf homogenates with subsequent nontargeted data processing to prevent a possible overlooking of volatile compounds. The more resistant genotypes are characterized by several negative sensory characteristics such as bitter, grassy, herbaceous, pungent, chemical, and harsh. In contrast, the contents of some volatile compounds correlate highly and significantly either with resistance (e.g., hexanal and -copaene) or with susceptibility (e.g., p-menthenol). Some of these compounds with very strong correlation to resistance are still unidentified and are presumed to act as resistance markers.


PubMed | Free University of Berlin and Institute for Ecological Chemistry
Type: Journal Article | Journal: Chemical senses | Year: 2016

Host foraging of parasitic wasps attacking insects living in stored food may be guided by volatile cues emanating from these postharvest products. However, little knowledge is available as to how habitat odor released from noninfested stored food affects the parasitoids response to host-specific chemicals. In this study, we investigated the impact of wheat grist odor on the olfactory host search by the ectoparasitoid Holepyris sylvanidis This parasitoid attacks larvae of the confused flour beetle Tribolium confusum, a common pest of grain products. Olfactometer bioassays showed that female H. sylvanidis were attracted by volatiles released from host larval feces, whereas odor of noninfested wheat grist was neither attractive nor did it mask the host-indicating cues. We analyzed the odor of host larval feces and wheat grist by coupled gaschromatography-mass spectrometry and recorded the parasitoids electroantennographic (EAG) responses to the detected volatiles. Two specifically host-associated components of the fecal odor, (E)-2-nonenal and 1-pentadecene, elicited strong EAG responses. Both components were attractive when tested individually, but less than larval feces. Attraction of parasitoids to these host-specific key compounds was enhanced by addition of (i) noninfested habitat substrate odor or (ii) a blend of 3 EAG-active (but not behaviorally active) volatiles that had been identified in odor of noninfested grist (benzaldehyde, 1-tetradecene, 1-hexadecene), but were also detected in the host fecal odor. The impact of these volatiles ubiquitously released in a food store by noninfested habitat substrate on the parasitoids orientation to host-specific volatile cues is discussed.

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