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May R Berenbaum - One of the best experts on this subject based on the ideXlab platform.
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Patterns of Genetic Diversity in the Globally Invasive Species Wild Parsnip (Pastinaca sativa)
2015Co-Authors: Tania Jogesh, Rhiannon Peery, Stephen R. Downie, May R BerenbaumAbstract:Wild Parsnip is an invasive species with a global distribution in temperate climates. Parsnips are native to Eurasia and have been cultivated for more than five centuries. It is unclear whether the global invasion of this species is a consequence of escape from cultivation or the accidental introduction of a Eurasian wild subspecies. In this study, we used nuclear ribosomal DNA internal transcribed spacer (ITS) and chloroplast DNA (cpDNA) markers to evaluate the genetic structure of wild Parsnip in its native range (Europe) and in three distinct geographic regions where it is considered invasive: eastern North America, western North America, and New Zealand. We also compared wild and cultivated Parsnips to determine whether they are genetically distinct. From 112 individuals, we recovered 14 ITS and 27 cpDNA haplotypes. One ITS haplotype was widespread; few haplotypes were rare singletons. In contrast, at least two lineages of cpDNA haplotypes were recovered, with several novel haplotypes restricted to Eu...
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implications of enemy escape on chemically mediated interactions with mutualists wild Parsnip pollination in two hemispheres
2014Co-Authors: Tania Jogesh, Arthur R. Zangerl, Margaret C Stanley, May R BerenbaumAbstract:When plant species invade new areas, they can escape from specialist enemies and thereby reduce investment in chemical defense. Enemy release may have other impacts on plant chemistry; in the absence of specialists, plants may be able to increase production of volatiles that enhance attractiveness to pollinators. In the United States (US), the introduced Eurasian wild Parsnip, Pastinaca sativa , has long been subject to attack by an introduced coevolved florivore, Depressaria pastinacella, the Parsnip webworm. In 2004, webworms were found for the first time attacking Parsnips in New Zealand (NZ). Relative to US P. sativa , NZ P. sativa produces lower levels of defenses but higher levels of certain floral volatiles, suggesting that escape from its specialist florivore may have resulted in changes in volatile profiles to increase pollinator attraction. In this study, we examined the influence of wild Parsnip floral volatiles on pollinator attraction and seed production in NZ and the US. While many insect groups were observed on Parsnip umbels, the percentage of flowers that set seed could significantly be predicted by the occurrence of large calyptrate flies and small syrphids in both localities. In the US, β-pinene, γ-terpinene, hexyl butyrate, octyl butyrate, germacrene D and an unknown monoterpene were all positively correlated with visitation by large calyptrates and small syrphids. In NZ, trans- ocimene, carene and octyl butyrate were positively correlated with visitation. Remarkably, most compounds positively associated with visitation are produced in significantly higher proportions in NZ flowers, suggesting that NZ flowers, in the absence of specialized florivores, may be chemically better constituted to attract pollinators.
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Parsnip webworms and host plants at home and abroad: trophic complexity in a geographic mosaic.
2006Co-Authors: May R Berenbaum, Arthur R. ZangerlAbstract:Due to differences in the structure of communities in which interactions are embedded, the intensity of interactions between species may vary with location; thus, what results from differences in outcomes and in degree of specialization is a geographic mosaic, which provides the raw material for divergent coevolutionary trajectories. Where selection intensity is great, reciprocal responses are likely in so-called "hotspots"; in contrast, where selection pressures are relaxed, reciprocal responses in "coldspots" are far less likely to occur. There are few if any studies examining how a gradient of increasing trophic complexity might influence the probability of phenotype matching and, correspondingly, the "temperature" of the coevolutionary interaction. This study was conducted to compare outcomes of the interaction between wild Parsnip (Pastinaca sativa) and Parsnip webworm (Depressaria pastinacella) in its indigenous area, Europe, to its area of introduction, the midwestern United States. Specifically, we tested the hypothesis that increasing trophic complexity, represented by alternate host plants or the presence of natural enemies, reduces the selective impact of Parsnip webworms and hence diminishes linkage between host plant chemistry and webworms that would be expected in coevolutionary hotspots. This comparison of a two-species interaction in its area of introduction and its area of indigeneity revealed common patterns that are more reflective of interaction temperature than of continental origin. Where webworms are rare, Parsnips produce lower levels of xanthotoxin and bergapten in both the midwestern United States and Netherlands populations. However, the most striking result from this intercontinental comparison is that what is a ubiquitous two-species interaction in North America is in fact exceptional in Europe; webworms could more reliably be found infesting H. sphondylium even where P. sativa was available as well. This preference for H. sphondylium exists despite the comparatively high probability of parasitism associated with this host plant and may reflect the overall lower furanocoumarin content of H. sphondylium. The interaction of Parsnip webworms and wild Parsnips at home and away demonstrates clearly the potential for rapid contemporary evolution of chemical traits upon re-association with a coevolved enemy, a potential evolutionary outcome that should be considered in the design and implementation of future weed biological control programs.
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PHENOTYPE MATCHING IN WILD Parsnip AND Parsnip WEBWORMS: CAUSES AND CONSEQUENCES
2003Co-Authors: Arthur R. Zangerl, May R BerenbaumAbstract:According to the geographic mosaic theory of coevolution, selection intensity in interactions varies across a landscape, forming a selection mosaic; interaction traits match at coevolutionary hotspots where selection is reciprocal and mismatch at coldspots where reciprocity is not a factor. Chemical traits play an important role in the interaction between wild Parsnip (Pastinaca sativa) and the Parsnip webworm (Depressaria pastinacella). Furanocoumarins, produced as plant defenses, are detoxified by the webworms by cytochrome P450 monooxygenases; significant additive genetic variation exists for both furanocoumarin production in the plant and detoxification in the insect, making these traits available for selection. To test the hypothesis that differences in selection intensity affect the distribution of coevolutionary hotspots and coldspots in this interaction, we examined 20 populations of webworms and wild Parsnips in Illinois and Wisconsin that varied in size, extent of infestation, proximity to woods (and potential vertebrate predators), and proximity to a chemically distinct alternate host plant, Heracleum lanatum (cow Parsnip). Twelve of 20 populations displayed phenotype matching between plant defense and insect detoxification profiles. Of the eight mismatched populations, a logistic regression model related matching probability to two predictors: the presence of the alternate host and average content of xanthotoxin (one of the five furanocoumarins produced by P. sativa). The odds of mismatching were significantly increased by the presence of the alternate host (odds ratio = 15.4) and by increased xanthotoxin content (odds ratio = 6.053). Parsnips growing near cow Parsnip displayed chemical phenotypes that were chemically intermediate between cow Parsnip and Parsnips growing in isolation. Rapid phenotype matching in this system is likely due in part to differential mortality every season; larvae transferred to a plant 30 m or more from the plant on which they developed tended to experience increased mortality over larvae transferred to another umbel on the same plant on which they had developed, and plant populations that mismatched in 2001 displayed a change in chemical phenotype distribution from the previous year. Trait mixing through gene flow is also a likely factor in determining mismatch frequency. Populations from which webworms were eradicated the previous year were all recolonized; in three of seven of these populations, infestation rates exceeded 90%. Our findings, consistent with the geographic mosaic theory, suggest that the presence of a chemically distinct alternate host plant can affect selection intensity in such a way as to reduce the likelihood of reciprocity in the coevolutionary interaction between wild Parsnip and the Parsnip webworm.
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behavioral responses of the Parsnip webworm to host plant volatiles
2002Co-Authors: Mark J. Carroll, May R BerenbaumAbstract:Sixth instars of the Parsnip webworm, Depressaria pastinacella, orient by olfaction to bud, male flowers, and female flowers of their primary host plant, Pastinaca sativa. Because octyl acetate and octyl butyrate are characteristic of tissues consumed by the sixth instar, we investigated the influence of these esters on webworm feeding behavior and chemo-orientation. Although octyl acetate and octyl butyrate are feeding deterrents, and octyl butyrate is an olfactory repellent, octyl acetate serves as an olfactory attractant. In olfactometers, webworms do not show a preference when given a choice between octyl acetate and host plant tissues. These findings suggest that octyl acetate is a sufficient cue for olfactory orientation. Such behavior may explain differences in the relative abundance of these esters observed among populations of wild Parsnip under differential selection pressure from these insects.
Arthur R. Zangerl - One of the best experts on this subject based on the ideXlab platform.
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implications of enemy escape on chemically mediated interactions with mutualists wild Parsnip pollination in two hemispheres
2014Co-Authors: Tania Jogesh, Arthur R. Zangerl, Margaret C Stanley, May R BerenbaumAbstract:When plant species invade new areas, they can escape from specialist enemies and thereby reduce investment in chemical defense. Enemy release may have other impacts on plant chemistry; in the absence of specialists, plants may be able to increase production of volatiles that enhance attractiveness to pollinators. In the United States (US), the introduced Eurasian wild Parsnip, Pastinaca sativa , has long been subject to attack by an introduced coevolved florivore, Depressaria pastinacella, the Parsnip webworm. In 2004, webworms were found for the first time attacking Parsnips in New Zealand (NZ). Relative to US P. sativa , NZ P. sativa produces lower levels of defenses but higher levels of certain floral volatiles, suggesting that escape from its specialist florivore may have resulted in changes in volatile profiles to increase pollinator attraction. In this study, we examined the influence of wild Parsnip floral volatiles on pollinator attraction and seed production in NZ and the US. While many insect groups were observed on Parsnip umbels, the percentage of flowers that set seed could significantly be predicted by the occurrence of large calyptrate flies and small syrphids in both localities. In the US, β-pinene, γ-terpinene, hexyl butyrate, octyl butyrate, germacrene D and an unknown monoterpene were all positively correlated with visitation by large calyptrates and small syrphids. In NZ, trans- ocimene, carene and octyl butyrate were positively correlated with visitation. Remarkably, most compounds positively associated with visitation are produced in significantly higher proportions in NZ flowers, suggesting that NZ flowers, in the absence of specialized florivores, may be chemically better constituted to attract pollinators.
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Parsnip webworms and host plants at home and abroad: trophic complexity in a geographic mosaic.
2006Co-Authors: May R Berenbaum, Arthur R. ZangerlAbstract:Due to differences in the structure of communities in which interactions are embedded, the intensity of interactions between species may vary with location; thus, what results from differences in outcomes and in degree of specialization is a geographic mosaic, which provides the raw material for divergent coevolutionary trajectories. Where selection intensity is great, reciprocal responses are likely in so-called "hotspots"; in contrast, where selection pressures are relaxed, reciprocal responses in "coldspots" are far less likely to occur. There are few if any studies examining how a gradient of increasing trophic complexity might influence the probability of phenotype matching and, correspondingly, the "temperature" of the coevolutionary interaction. This study was conducted to compare outcomes of the interaction between wild Parsnip (Pastinaca sativa) and Parsnip webworm (Depressaria pastinacella) in its indigenous area, Europe, to its area of introduction, the midwestern United States. Specifically, we tested the hypothesis that increasing trophic complexity, represented by alternate host plants or the presence of natural enemies, reduces the selective impact of Parsnip webworms and hence diminishes linkage between host plant chemistry and webworms that would be expected in coevolutionary hotspots. This comparison of a two-species interaction in its area of introduction and its area of indigeneity revealed common patterns that are more reflective of interaction temperature than of continental origin. Where webworms are rare, Parsnips produce lower levels of xanthotoxin and bergapten in both the midwestern United States and Netherlands populations. However, the most striking result from this intercontinental comparison is that what is a ubiquitous two-species interaction in North America is in fact exceptional in Europe; webworms could more reliably be found infesting H. sphondylium even where P. sativa was available as well. This preference for H. sphondylium exists despite the comparatively high probability of parasitism associated with this host plant and may reflect the overall lower furanocoumarin content of H. sphondylium. The interaction of Parsnip webworms and wild Parsnips at home and away demonstrates clearly the potential for rapid contemporary evolution of chemical traits upon re-association with a coevolved enemy, a potential evolutionary outcome that should be considered in the design and implementation of future weed biological control programs.
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PHENOTYPE MATCHING IN WILD Parsnip AND Parsnip WEBWORMS: CAUSES AND CONSEQUENCES
2003Co-Authors: Arthur R. Zangerl, May R BerenbaumAbstract:According to the geographic mosaic theory of coevolution, selection intensity in interactions varies across a landscape, forming a selection mosaic; interaction traits match at coevolutionary hotspots where selection is reciprocal and mismatch at coldspots where reciprocity is not a factor. Chemical traits play an important role in the interaction between wild Parsnip (Pastinaca sativa) and the Parsnip webworm (Depressaria pastinacella). Furanocoumarins, produced as plant defenses, are detoxified by the webworms by cytochrome P450 monooxygenases; significant additive genetic variation exists for both furanocoumarin production in the plant and detoxification in the insect, making these traits available for selection. To test the hypothesis that differences in selection intensity affect the distribution of coevolutionary hotspots and coldspots in this interaction, we examined 20 populations of webworms and wild Parsnips in Illinois and Wisconsin that varied in size, extent of infestation, proximity to woods (and potential vertebrate predators), and proximity to a chemically distinct alternate host plant, Heracleum lanatum (cow Parsnip). Twelve of 20 populations displayed phenotype matching between plant defense and insect detoxification profiles. Of the eight mismatched populations, a logistic regression model related matching probability to two predictors: the presence of the alternate host and average content of xanthotoxin (one of the five furanocoumarins produced by P. sativa). The odds of mismatching were significantly increased by the presence of the alternate host (odds ratio = 15.4) and by increased xanthotoxin content (odds ratio = 6.053). Parsnips growing near cow Parsnip displayed chemical phenotypes that were chemically intermediate between cow Parsnip and Parsnips growing in isolation. Rapid phenotype matching in this system is likely due in part to differential mortality every season; larvae transferred to a plant 30 m or more from the plant on which they developed tended to experience increased mortality over larvae transferred to another umbel on the same plant on which they had developed, and plant populations that mismatched in 2001 displayed a change in chemical phenotype distribution from the previous year. Trait mixing through gene flow is also a likely factor in determining mismatch frequency. Populations from which webworms were eradicated the previous year were all recolonized; in three of seven of these populations, infestation rates exceeded 90%. Our findings, consistent with the geographic mosaic theory, suggest that the presence of a chemically distinct alternate host plant can affect selection intensity in such a way as to reduce the likelihood of reciprocity in the coevolutionary interaction between wild Parsnip and the Parsnip webworm.
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Effects of furanocoumarins on feeding behavior of Parsnip webworms Depressaria pastinacella
2002Co-Authors: J. A. Cianfrogna, Arthur R. Zangerl, May R BerenbaumAbstract:The Parsnip webworm, Depressaria pastinacella, exhibits limited physiological resistance to furanocoumarin toxins in its principal host, the wild Parsnip, Pastinaca sativa. These insects are typically found attacking individual plants low in furanocoumarins, relative to others within populations. They also feed preferentially on parthenocarpic fruits, which are lower in furanocoumarin content than are normal fruits. However, in a previous study with artificial diets, they did not appear to discriminate between high and low concentrations of furanocoumarins. In this study, the ability of webworms to distinguish between diets differing in furanocoumarin content was examined with an artificial diet containing wild Parsnip and in green Parsnip fruits with and without supplemental furanocoumarins. Larvae showed no preference for high or low furanocoumarin diets containing equal amounts of freeze-dried Parsnip fruit powder. When given a choice between otherwise similar wild Parsnip fruits, webworms strongly preferred fruits that were not augmented with furanocoumarins in one plant but showed no preference or only a weak preference for nonaugmented fruits in four other plants. In order to identify chemical constituents other than furanocoumarins that might determine feeding preferences, we compared the chemical profile of parthenocarpic fruits (which are preferred) to that of normal fruit. Octyl butyrate, a known deterrent to webworms, is highly correlated with furanocoumarin content, occurs in all plants, and differs significantly among normal and parthenocarpic fruit, suggesting that webworms may be able to avoid furanocoumarins by virtue of their behavioral response to octyl butyrate.
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heritability estimates for octyl acetate and octyl butyrate in the mature fruit of the wild Parsnip
2000Co-Authors: Mark J. Carroll, Arthur R. Zangerl, May R BerenbaumAbstract:The aliphatic esters octyl acetate and octyl butyrate occur as major components of essential oils in the vittae, or oil tubes, of the wild Parsnip (Pastinaca sativa). We determined phenotypic variation and narrow-sense heritabilities of these octyl esters in wild Parsnip fruits from 30 maternal families. The mean octyl acetate content was 1.56 microg/mg dry fruit (0.08-5.51 microg/mg dry fruit) and the mean octyl butyrate content was 4.28 microg/mg dry fruit (1.28-14.22 microg/ mg dry fruit). Narrow-sense heritabilities for each ester's content were calculated by analysis of half-sib families (HS) and parent-offspring regression (OP). Heritabilities were 0.389 (HS) and 0.654 (OP) for octyl acetate and 0.670 (HS) and 0.626 (OP) for octyl butyrate. The amounts of the esters were phenotypically correlated with each other and with the linear furanocoumarins bergapten and xanthotoxin, phototoxic compounds that co-occur in the vittae with the esters. Ester amounts were not genetically correlated, indicating that these compounds could respond independently to selection pressures. These octyl esters may serve as carrier solvents that enhance penetration of these furanocoumarins into herbivore integuments and gut walls.
Alejandra Castro - One of the best experts on this subject based on the ideXlab platform.
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Physicochemical properties of root fiber suspensions. A comparison between Parsnip (Pastinaca sativa) and yacon (Smallanthus sonchifolius)
2013Co-Authors: Alejandra CastroAbstract:Popular Abstract in English The current interest in improving the nutritional benefits of food products and the need to recover undeveloped crops prompted us to study two plant roots: Parsnip (Pastinaca sativa) and yacon (Smallanthus sonchifolius). Parsnip is a root native to Europe and Asia, and is often used for culinary purposes and to feed livestock. Parsnip was a popular vegetable in the Middle Ages but the interest in this root declined with the arrival of the potato in Europe. Yacon roots are originally from Andean countries in South America, cultivated since pre-colonial times, and it is commonly eaten raw as a fruit due to its slightly sweet taste and crunchy texture. The cultivation of yacon in Andean countries declined slowly through most of the past century, limiting access to this root and its commercialization. However, interest has been growing steadily in the past ten years due to studies showing its health benefits. The study and evaluation of the properties of these two roots might help to increase interest in these roots and their further industrial use. Parsnip and yacon roots have a dry matter content of 20% and 10%, respectively. The two roots differ in their storage polysaccharide (i.e. the plant’s energy source). The storage polysaccharide in Parsnip is starch, whereas the storage polysaccharide in yacon is fructans. These fructans also have dietary fiber properties. The dietary fiber in Parsnip mainly comprises the cell wall polysaccharides (cellulose, hemicellulose, and pectin substances), whereas the dietary fiber in yacon is mainly fructans and only a small proportion in the form of cellulose, hemicellulose, and pectin. Parsnip and yacon roots are both a promising source of dietary fiber with relatively high values of about 30% (Parsnip) and 45% (yacon) of the dry matter. Yacon in particular is a significant source of fructans. Another difference between these two roots is the amount of dietary fiber determined as soluble and insoluble. Most of the dietary fiber in Parsnip is obtained as insoluble dietary fiber while, in yacon, most is obtained as soluble dietary fiber. Parsnip and yacon roots in the form of pastes were used to prepare aqueous suspensions by suspending the paste in distilled water. These aqueous suspensions were subjected to processes such as valve pressure homogenization and heating. These two processes are often used in industrial processing of these types of materials. Properties such as the amount of insoluble particles, the particle size distribution, and the volume fraction of the particles were measured in the suspensions, and then related to the rheological properties. Parsnip and yacon suspensions initially comprised cell clusters, but homogenization broke these cell clusters. After homogenization, Parsnip suspensions had smaller cell clusters and some single cells; yacon suspensions after homogenization, besides presenting smaller cell clusters, also presented aggregation of cell fragments. Yacon cells were slightly easier to disrupt by homogenization than Parsnip cells. Parsnip and yacon suspensions displayed ‘solid-like’ rheological behavior (Gʹ>Gʹʹ) because of the amount of insoluble particles in the suspension. Parsnip suspensions started to present a rather strong particle network when the concentration of insoluble particles (i.e. cell fragments) was quite high (around 2.7 g/100 g suspension). In contrast, yacon suspensions already exhibited a strong particle network at a rather low concentration of insoluble particles (around 0.7 g/100 g suspension). We should remember that yacon contains a significant amount of fructans, but these are mainly found in the soluble fraction (i.e. often not considered as particles but as soluble polysaccharides). Results from our investigation suggested that these ‘soluble’ fructans form small particles with sizes in the nano-range. Besides the amount of particles, particle properties such as rigidity are also important in the rheological properties of concentrated Parsnip suspensions (above 2.7 g insoluble particles/100 g suspensions). When Parsnip suspensions were heated at 60°C for 40 min, an enzyme (pectin methyl esterase) was activated. This enzyme facilitated the cross-link of pectin chains in cell walls of the particles and so the rigidity of the particles increased. Parsnip suspensions with these types of particles showed enhanced rheological properties. Conversely, when Parsnip suspensions were heated at 80°C for 2h, chemical reactions occurred that solubilized pectin. The solubilization of pectin from the cell walls reduced the rigidity of the particles. Parsnip suspensions with these types of particles showed lower elastic properties than suspensions with rigid particles. (Less)
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Effect of heat treatment and homogenization on the rheological properties of aqueous Parsnip suspensions
2013Co-Authors: Alejandra Castro, Björn Bergenståhl, Eva TornbergAbstract:Parsnip (Pastinaca sativa) suspensions, at concentrations corresponding to a dilute and concentrated regime, were subjected to pasteurization, and heat treatments that favored beta-elimination reactions and pectin methyl esterase activity. The different heat treatments were combined with homogenization. Physicochemical properties such as content of insoluble/soluble material and insoluble/soluble pectin were measured together with particle and rheological properties. Pectin methyl esterase activity led to a high yield of insoluble material and insoluble pectin, whereas beta-elimination led to a high yield of soluble material and solubilized pectin. Homogenization after heat treatment resulted in increased solubilization of the pectin, especially after beta-elimination reactions. Parsnip suspensions subjected to pectin methyl esterase activity exhibited the highest elastic modulus most likely due to the cross-linked pectin conferring rigidity to the cell walls. The content of insoluble material and the particle properties such as size and rigidity are important factor for the rheological properties of concentrated Parsnip suspensions. (Less)
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Parsnip (Pastinaca sativa L.): Dietary fibre composition and physicochemical characterization of its homogenized suspensions
2012Co-Authors: Alejandra Castro, Björn Bergenståhl, Eva TornbergAbstract:Abstract The dietary fibre composition in Parsnip has been determined in the soluble and insoluble fraction, together with the physicochemical properties (morphology of particles, particle size distribution (PSD), volume fraction and rheological properties) of the Parsnip suspensions at different paste concentration and degree of homogenization. The content of dietary fibre in Parsnip was 30.4% of the dry matter, composed mainly by neutral sugars (18.4%), pectic substances (10.10%) and Klason lignin (1.92%). Homogenization affected the particle size distribution of Parsnip suspension (p d 32 L ) and the volume percentage of large particles ( vol L %) decreased, whereas the volume percentage of small particles ( vol S %) increased. Concentration affected the rheological properties of Parsnip suspensions (p ϕ ) increased with paste concentration but was reduced with homogenization. By plotting the elastic modulus, G ′, as a function of volume fraction, ϕ , we showed the existence of a diluted and concentrated regime with a transition region at approximately ϕ = 19% for Parsnip suspensions. Above the transition region, concentration of particles played an important role for the rheological properties. Based on the results achieved in this investigation we suggest that the gel network is mainly formed by the large particles, e.g. > 100 μm, and the smaller are preferably in the voids between the larger ones.
Eva Tornberg - One of the best experts on this subject based on the ideXlab platform.
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Effect of heat treatment and homogenization on the rheological properties of aqueous Parsnip suspensions
2013Co-Authors: Alejandra Castro, Björn Bergenståhl, Eva TornbergAbstract:Parsnip (Pastinaca sativa) suspensions, at concentrations corresponding to a dilute and concentrated regime, were subjected to pasteurization, and heat treatments that favored beta-elimination reactions and pectin methyl esterase activity. The different heat treatments were combined with homogenization. Physicochemical properties such as content of insoluble/soluble material and insoluble/soluble pectin were measured together with particle and rheological properties. Pectin methyl esterase activity led to a high yield of insoluble material and insoluble pectin, whereas beta-elimination led to a high yield of soluble material and solubilized pectin. Homogenization after heat treatment resulted in increased solubilization of the pectin, especially after beta-elimination reactions. Parsnip suspensions subjected to pectin methyl esterase activity exhibited the highest elastic modulus most likely due to the cross-linked pectin conferring rigidity to the cell walls. The content of insoluble material and the particle properties such as size and rigidity are important factor for the rheological properties of concentrated Parsnip suspensions. (Less)
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Parsnip (Pastinaca sativa L.): Dietary fibre composition and physicochemical characterization of its homogenized suspensions
2012Co-Authors: Alejandra Castro, Björn Bergenståhl, Eva TornbergAbstract:Abstract The dietary fibre composition in Parsnip has been determined in the soluble and insoluble fraction, together with the physicochemical properties (morphology of particles, particle size distribution (PSD), volume fraction and rheological properties) of the Parsnip suspensions at different paste concentration and degree of homogenization. The content of dietary fibre in Parsnip was 30.4% of the dry matter, composed mainly by neutral sugars (18.4%), pectic substances (10.10%) and Klason lignin (1.92%). Homogenization affected the particle size distribution of Parsnip suspension (p d 32 L ) and the volume percentage of large particles ( vol L %) decreased, whereas the volume percentage of small particles ( vol S %) increased. Concentration affected the rheological properties of Parsnip suspensions (p ϕ ) increased with paste concentration but was reduced with homogenization. By plotting the elastic modulus, G ′, as a function of volume fraction, ϕ , we showed the existence of a diluted and concentrated regime with a transition region at approximately ϕ = 19% for Parsnip suspensions. Above the transition region, concentration of particles played an important role for the rheological properties. Based on the results achieved in this investigation we suggest that the gel network is mainly formed by the large particles, e.g. > 100 μm, and the smaller are preferably in the voids between the larger ones.
Mark J. Carroll - One of the best experts on this subject based on the ideXlab platform.
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behavioral responses of the Parsnip webworm to host plant volatiles
2002Co-Authors: Mark J. Carroll, May R BerenbaumAbstract:Sixth instars of the Parsnip webworm, Depressaria pastinacella, orient by olfaction to bud, male flowers, and female flowers of their primary host plant, Pastinaca sativa. Because octyl acetate and octyl butyrate are characteristic of tissues consumed by the sixth instar, we investigated the influence of these esters on webworm feeding behavior and chemo-orientation. Although octyl acetate and octyl butyrate are feeding deterrents, and octyl butyrate is an olfactory repellent, octyl acetate serves as an olfactory attractant. In olfactometers, webworms do not show a preference when given a choice between octyl acetate and host plant tissues. These findings suggest that octyl acetate is a sufficient cue for olfactory orientation. Such behavior may explain differences in the relative abundance of these esters observed among populations of wild Parsnip under differential selection pressure from these insects.
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heritability estimates for octyl acetate and octyl butyrate in the mature fruit of the wild Parsnip
2000Co-Authors: Mark J. Carroll, Arthur R. Zangerl, May R BerenbaumAbstract:The aliphatic esters octyl acetate and octyl butyrate occur as major components of essential oils in the vittae, or oil tubes, of the wild Parsnip (Pastinaca sativa). We determined phenotypic variation and narrow-sense heritabilities of these octyl esters in wild Parsnip fruits from 30 maternal families. The mean octyl acetate content was 1.56 microg/mg dry fruit (0.08-5.51 microg/mg dry fruit) and the mean octyl butyrate content was 4.28 microg/mg dry fruit (1.28-14.22 microg/ mg dry fruit). Narrow-sense heritabilities for each ester's content were calculated by analysis of half-sib families (HS) and parent-offspring regression (OP). Heritabilities were 0.389 (HS) and 0.654 (OP) for octyl acetate and 0.670 (HS) and 0.626 (OP) for octyl butyrate. The amounts of the esters were phenotypically correlated with each other and with the linear furanocoumarins bergapten and xanthotoxin, phototoxic compounds that co-occur in the vittae with the esters. Ester amounts were not genetically correlated, indicating that these compounds could respond independently to selection pressures. These octyl esters may serve as carrier solvents that enhance penetration of these furanocoumarins into herbivore integuments and gut walls.
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behavioral effects of carotenoid sequestration by the Parsnip webworm depressaria pastinacella
1997Co-Authors: Mark J. Carroll, Arthur R. Zangerl, Amy Hanlon, Tanya Hanlon, May R BerenbaumAbstract:The Parsnip webwormDepressaria pastinacella, acquires a distinct yellow stripe when it consumes the yellow flowers of its principal host plantPastinaca sativa, the wild Parsnip. Caterpillars raised on artificial diet lacking host-plant material lack this yellow coloration. By chemical characterization and comparison of caterpillars raised on Parsnip flowers and on artificial diet, we were able to determine that lutein, along with smaller amounts of other xanthophylls from the host plant, is selectively sequestered in the fat body. In bioassays designed to measure avoidance of ultraviolet light, caterpillars raised on Parsnip flowers or on artificial diet supplemented with lutein were less likely to avoid exposure to ultraviolet light than caterpillars raised on unaugmented artificial diet and thus lacking sequestered carotenoids. The ability to sequester xanthophylls, which are highly effective antioxidants, may confer a selective advantage on these caterpillars, whose apiaceous host plants produce large quantities of furanocoumarins, natural products that are photoactivated by light wavelengths in the ultraviolet region; such sequestered pigments may reduce not only the oxidative stress associated with ultraviolet light and diurnal foraging but also the photooxidative stress associated with ingestion of photoactive furanocoumarins.