Eddy van der Meijden - Academia.edu (original) (raw)

Papers by Eddy van der Meijden

Insect Populations In theory and in practice, 1998

The relationship between the cinnabar moth, Tyria jacobaeae, a specialist herbivore, and its food... more The relationship between the cinnabar moth, Tyria jacobaeae, a specialist herbivore, and its food plant ragwort, Senecio jacobaea, involves periodic total defoliation (and defloration) of the plant, followed by population crashes of the insect. The insect is not only dependent on ragwort for food, but also for the plant’ secondary chemicals - pyrrolizidine alkaloids - that are sequestered by the larvae and probably function as a protection against natural enemies.

Theoretical Population Biology, 1999

Phytochemistry, 1991

... Pergamon Press pieCONTROL AND BIOLOGICAL IMPLICATIONS OF ALKALOID SYNTHESISIN CINCHONA SEEDLI... more ... Pergamon Press pieCONTROL AND BIOLOGICAL IMPLICATIONS OF ALKALOID SYNTHESISIN CINCHONA SEEDLINGSROB J. AERTS,* WIM SNOEIJER, OLGA AERTS-TEERLINK ... see Experimental).10-t-7.5-cim 5-"0P2.5-__.mi 0:3 3 ioalkaloid concentration (raM)-10E-7.501 ...

Journal of Chemical Ecology, 2006

The metabolic alterations of Brassica rapa (L.) leaves attacked by larvae of the specialist Plute... more The metabolic alterations of Brassica rapa (L.) leaves attacked by larvae of the specialist Plutella xylostella L. (Lepidoptera: Yponomeutidae) and the generalist Spodoptera exigua Hubner (Lepidoptera: Noctuidae) were investigated with nuclear magnetic resonance (NMR) spectroscopy, followed by a multivariate data analysis. The principal component analysis (PCA) of (1)H NMR spectra showed that metabolic changes in B. rapa leaves induced by the 2nd and the 4th instars were different from each other. However, the congestion of the one-dimensional (1)H NMR spectrum made it difficult to identify discriminating metabolites. To overcome the spectral complexity, several two-dimensional NMR techniques were applied. Of those evaluated, J-resolved spectroscopy, which affords an additional coupling constant, provided a wide range of structure information on differentiating the metabolites. Based on the J-resolved spectra combined with PCA, the major signals contributing to the discrimination were alanine, threonine, glucose, sucrose, feruloyl malate, sinapoyl malate, and gluconapin.

Journal of Chemical Ecology, 1996

Tbe involvement of the glucoalkatoid strictosidine in antimicrobial and antifeedant activity in C... more Tbe involvement of the glucoalkatoid strictosidine in antimicrobial and antifeedant activity in Catharonthus roseus leaves was investigated. Strictosidine and its degiucosylalion pn~uct, specifically formed by the enzyme strictosidine glucosidase, were shown to be active against several microorganisms. In contrast, neither the intact glucoside, nor the aglycone product(s) was found to exhibit antifeedant activity against Spodoptera exigua larvae, as was found for intact C. roseus leaves and leaf extracts. Besides alkaloids further downstream in the biosynthesis pathway, a more apolar, yet unidentified compound may be involved in this activity.

Journal of Chemical Ecology, 2010

We examined the effects of water and nutrient availability on the expression of the defense pyrro... more We examined the effects of water and nutrient availability on the expression of the defense pyrrolizidine alkaloids (PAs) in Senecio jacobaea and S. aquaticus. Senecio jacobaea, and S. aquaticus are adapted to different natural habitats, characterized by differing abiotic conditions and different selection pressures from natural enemies. We tested if PA concentration and diversity are plastic over a range of water and nutrient treatments, and also whether such plasticity is dependent on plant species. We also tested the hypothesis that hybridization may contribute to PA diversity within plants, by comparing PA expression in parental species to that in artificially generated F 1 hybrids, and also in later generation natural hybrids between S. jacobaea and S. aquaticus. We showed that total PA concentration in roots and shoots is not dependent on species, but that species determines the pattern of PA diversification. Pyrrolizidine alkaloid diversity and concentration are both dependent on environmental factors. Hybrids produce a putatively novel PA, and this PA is conserved in natural hybrids, that are backcrossed to S. jacobaea. Natural hybrids that are backcrossed several times to S. jacobaea are with regard to PA diversity significantly different from S. jacobaea but not from S. aquaticus, while F 1 hybrids are in all cases more similar to S. jacobaea. These results collectively suggest that PA diversity is under the influence of natural selection.

A recently discovered feature of plant– flower visitor webs is the asymmetric specialization of t... more A recently discovered feature of plant– flower visitor webs is the asymmetric specialization of the interaction partners: specialized plants interact mainly with generalized flower visitors and specialized flower visitors mainly with generalized plants. Little is known about the factors leading to this asymmetry and their consequences for the extinction risk of species. Previous studies have proposed random interactions proportional to species abundance as an explanation. However, the simulation models used in these studies did not include potential biological constraints. In the present study, we tested the potential role of both morphological constraints and species abundance in promoting asymmetric specialization. We compared actual field data of a Mediterranean plant–flower visi-tor web with predictions of Monte Carlo simulations including different combinations of the potential fac-tors structuring the web. Our simulations showed that both nectar-holder depth and abundance were...

flower abundance determine the number of interactions in a plant/flower visitor web.

Oecologia, Apr 1, 2007

A recently discovered feature of plantflower visitor webs is the asymmetric specialization of the... more A recently discovered feature of plantflower visitor webs is the asymmetric specialization of the interaction partners: specialized plants interact mainly with generalized flower visitors and specialized flower visitors mainly with generalized plants. Little is known about the factors leading to this asymmetry and their consequences for the extinction risk of species. Previous studies have proposed random interactions proportional to species abundance as an explanation. However, the simulation models used in these studies did not include potential biological constraints. In the present study, we tested the potential role of both morphological constraints and species abundance in promoting asymmetric specialization. We compared actual field data of a Mediterranean plant-flower visitor web with predictions of Monte Carlo simulations including different combinations of the potential factors structuring the web. Our simulations showed that both nectar-holder depth and abundance were able to produce asymmetry; but that the expected degree of asymmetry was stronger if based on both. Both factors can predict the number of interaction partners, but only nectar-holder depth was able to predict the degree of asymmetry of a certain species. What is more, without the size threshold the influence of abundance would disappear over time. Thus, asymmetric specialization seems to be the result of a size threshold and, only among the allowed interactions above this size threshold, a result of random interactions proportional to abundance. The simulations also showed that asymmetric specialization could not be the reason that the extinction risk of specialists and generalists is equalized, as suggested in the literature. In asymmetric webs specialists clearly had higher short-term extinction risks. In fact, primarily generalist visitors seem to profit from asymmetric specialization. In our web, specialists were less abundant than generalists. Therefore, including abundance in the simulation models increased the difference between specialists and generalists even more.

Journal of insect science (Online), Jan 6, 2005

A so-called R-gene renders the yellow-striped flea beetle Phyllotreta nemorum L. (Coleoptera: Chr... more A so-called R-gene renders the yellow-striped flea beetle Phyllotreta nemorum L. (Coleoptera: Chrysomelidae: Alticinae) resistant to the defenses of the yellow rocket Barbarea vulgaris R.Br. (Brassicacea) and enables it to use it as a host plant in Denmark. In this study, genetic markers for an autosomal R-gene, inherited as a single, dominant locus in flea beetles from the Danish locality "Kvaerkeby" are described, and a genetic linkage map around this particular R-gene is constructed, using the technique of AFLP (Amplified Fragment Length Polymorphism).

New Phytologist, 2005

Hybridization may lead to unique phytochemical expression in plant individuals. Hybrids may expre... more Hybridization may lead to unique phytochemical expression in plant individuals. Hybrids may express novel combinations or extreme concentrations of secondary metabolites or, in some cases, produce metabolites novel to both parental species. Here we test whether there is evidence for extreme metabolite expression or novelty in F1 hybrids between Senecio aquaticus and Senecio jacobaea. Hybridization is thought to occur frequently within Senecio, and hybridization might facilitate secondary metabolite diversification within this genus. Parental species express different quantities of several classes of compounds known to be involved in antiherbivore defence, including pyrrolizidine alkaloids, chlorogenic acid, flavonoids and benzoquinoids. Hybrids demonstrate differential expression of some metabolites, producing lower concentrations of amino acids, and perhaps flavonoids, than either parental species. Despite evidence for quantitative hybrid novelty in this system, NMR profiling did not detect any novel compounds among the plant groups studied. Metabolomic profiling is a useful technique for identifying qualitative changes in major metabolites according to plant species and/or genotype, but is less useful for identifying small differences between plant groups, or differences in compounds expressed in low concentrations.

Principles of Plant-Microbe Interactions, 2014

It is estimated that, in spite of plant breeding and pest control efforts, 15 % of crop yield is ... more It is estimated that, in spite of plant breeding and pest control efforts, 15 % of crop yield is worldwide lost to herbivory by insects. Examples demonstrate how insect pests have developed in the past and why they will develop in the future. The evolutionary potential of insects to become new pests is considered for traditionally and genetically modified crop varieties. The immune system of plants is presented step by step. Generalist herbivores can be effectively repelled, but specialist herbivores are much harder to repel. They use plant defenses as cues for host plant recognition. Next to direct defense, indirect defense by attracting natural enemies of (specialist) herbivores is explained. Finally, the interactions of plants and insect herbivores with microbial symbionts—and their consequences—are discussed.

Biology of Plant Metabolomics, 2011

... Nicole M. van Dam1 and Eddy van der Meijden2 ... An important prediction of the theory on opt... more ... Nicole M. van Dam1 and Eddy van der Meijden2 ... An important prediction of the theory on optimal defence in plants (Coley et al., 1985) is that plants that are adapted to poor environments will invest more (energy and/or nutrients) in defence compounds than plants adapted to ...

Annals of Botany, 2009

† Background and Aims Many recent studies show that plant-pollinator interaction webs exhibit con... more † Background and Aims Many recent studies show that plant-pollinator interaction webs exhibit consistent structural features such as long-tailed distributions of the degree of generalization, nestedness of interactions and asymmetric interaction dependencies. Recognition of these shared features has led to a variety of mechanistic attempts at explanation. Here it is hypothesized that beside size thresholds and species abundances, the frequency distribution of sizes (nectar depths and proboscis lengths) will play a key role in determining observed interaction patterns. † Methods To test the influence of size distributions, a new network parameter is introduced: the degree of size matching between nectar depth and proboscis length. The observed degree of size matching in a Spanish plantpollinator web was compared with the expected degree based on joint probability distributions, integrating size thresholds and abundance, and taking the sampling method into account. † Key Results Nectar depths and proboscis lengths both exhibited right-skewed frequency distributions across species and individuals. Species-based size matching was equally close for plants, independent of nectar depth, but differed significantly for pollinators of dissimilar proboscis length. The observed patterns were predicted well by a model considering size distributions across species. Observed size matching was closer when relative abundances of species were included, especially for flowers with openly accessible nectar and pollinators with long proboscises, but was predicted somewhat less successfully by the model that included abundances. † Conclusions The results suggest that in addition to size thresholds and species abundances, size distributions are important for understanding interaction patterns in plant-pollinator webs. It is likely that the understanding will be improved further by characterizing for entire communities how nectar production of flowers and energetic requirements of pollinators covary with size, and how sampling methods influence the observed interaction patterns.

Plant Ecology, 2009

To explore genetic variation in defence against the natural herbivores of Arabidopsis thaliana, w... more To explore genetic variation in defence against the natural herbivores of Arabidopsis thaliana, we transplanted genotypes between a dune habitat and inland habitat in both of which A. thaliana occurred naturally. In previous years we had observed that the specialist weevils Ceutorhynchus atomus and C. contractus (Curculionidae) fed conspicuously on flowers and fruits of A. thaliana in the dunes, while these weevils were always rare in inland habitats. Taking all plants together, total fruit damage was indeed much higher in our experimental plots in the dune habitat (59.7%) relative to the inland garden habitat (18.9%). Within a habitat, additional differences existed between plants of different origins, pointing to genetic differences in ecologically relevant characters; plants of inland origin flowered a week earlier, grew better and produced more fruits than plants of dune origin. However, plants of inland origin experienced more total fruit damage by the specialist weevils (75.4%) than plants of dune origin (44.0%) when the two types grew side by side in the dune habitat. Escape from herbivory gives dune genotypes an advantage in their native habitat, whereas stronger growth and higher survival gives inland genotypes an edge under garden conditions.