Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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    Ozone affects growth and development of Pieris brassicae on the wild host plant Brassica nigra
    Khaling, E. ; Papazian, S. ; Poelman, E.H. ; Holopainen, J.K. ; Albrectsen, B.R. ; Blande, J.D. - \ 2015
    Environmental Pollution 199 (2015). - ISSN 0269-7491 - p. 119 - 129.
    elevated atmospheric co2 - beetle epilachna-varivestis - betula-pendula roth - glucosinolate concentrations - secondary metabolites - feeding preference - oviposition preference - specialist herbivores - plutella-xylostella - leaf beetle
    When plants are exposed to ozone they exhibit changes in both primary and secondary metabolism, which may affect their interactions with herbivorous insects. Here we investigated the performance and preferences of the specialist herbivore Pieris brassicae on the wild plant Brassica nigra under elevated ozone conditions. The direct and indirect effects of ozone on the plant-herbivore system were studied. In both cases ozone exposure had a negative effect on P. brassicae development. However, in dual-choice tests larvae preferentially consumed plant material previously fumigated with the highest concentration tested, showing a lack of correlation between larval preference and performance on ozone exposed plants. Metabolomic analysis of leaf material subjected to combinations of ozone and herbivore-feeding, and focussing on known defence metabolites, indicated that P. brassicae behaviour and performance were associated with ozone-induced alterations to glucosinolate and phenolic pools.
    Artificial light at night causes diapause inhibition and sex-specific life history changes in a moth
    Geffen, K.G. van; Grunsven, R.H.A. van; Ruijven, J. van; Berendse, F. ; Veenendaal, E.M. - \ 2014
    Ecology and Evolution 4 (2014)11. - ISSN 2045-7758 - p. 2082 - 2089.
    epirrita-autumnata lepidoptera - body-size - plutella-xylostella - utetheisa-ornatrix - diamondback moth - lobesia-botrana - flight ability - geometridae - biodiversity - plasticity
    Rapidly increasing levels of light pollution subject nocturnal organisms to major alterations of their habitat, the ecological consequences of which are largely unknown. Moths are well-known to be attracted to light at night, but effects of light on other aspects of moth ecology, such as larval development and life-history, remain unknown. Such effects may have important consequences for fitness and thus for moth population sizes. To study the effects of artificial night lighting on development and life-history of moths, we experimentally subjected Mamestra brassicae (Noctuidae) caterpillars to low intensity green, white, red or no artificial light at night and determined their growth rate, maximum caterpillar mass, age at pupation, pupal mass and pupation duration. We found sex-specific effects of artificial light on caterpillar life-history, with male caterpillars subjected to green and white light reaching a lower maximum mass, pupating earlier and obtaining a lower pupal mass than male caterpillars under red light or in darkness. These effects can have major implications for fitness, but were absent in female caterpillars. Moreover, by the time that the first adult moth from the dark control treatment emerged from its pupa (after 110 days), about 85% of the moths that were under green light and 83% of the moths that were under white light had already emerged. These differences in pupation duration occurred in both sexes and were highly significant, and likely result from diapause inhibition by artificial night lighting. We conclude that low levels of nocturnal illumination can disrupt life-histories in moths and inhibit the initiation of pupal diapause. This may result in reduced fitness and increased mortality. The application of red light, instead of white or green light, might be an appropriate measure to mitigate negative artificial light effects on moth life history.
    Dealing with double trouble: consequences of single and double herbivory in Brassica juncea
    Mathur, V. ; Tytgat, T.O.G. ; Graaf, R.M. de; Kalia, V. ; Reddy, A.S. ; Vet, L.E.M. ; Dam, N.M. van - \ 2013
    Chemoecology 23 (2013)2. - ISSN 0937-7409 - p. 71 - 82.
    induced plant-responses - milkweed asclepias-syriaca - plutella-xylostella - specialist herbivores - induced resistance - diamondback moth - wild radish - nicotiana-attenuata - insect resistance - black mustard
    In their natural environment, plants are often attacked simultaneously by many insect species. The specificity of induced plant responses that is reported after single herbivore attacks may be compromised under double herbivory and this may influence later arriving herbivores. The present study focuses on the dynamics of induced plant responses induced by single and double herbivory, and their effects on successive herbivores. Morphological (leaf length, area and trichome density) and chemical changes (leaf alkenyl and indole glucosinolates) in Brassica juncea were evaluated 4, 10, 14 and 20 days after damage by the specialist Plutella xylostella alone, or together with the generalist Spodoptera litura. To assess the biological effect of the plant's responses, the preference and performance of both herbivores on previously induced plants were measured. We found that alkenyl glucosinolates were induced 20 days after damage by P. xylostella alone, whereas their levels were elevated as early as 4 days after double herbivory. Trichome density was increased in both treatments, but was higher after double herbivory. Interestingly, there was an overall decrease in indole glucosinolates and an increase in leaf size due to damage by P. xylostella, which was not observed during double damage. S. litura preferred and performed better on undamaged plants, whereas P. xylostella preferred damaged plants and performed better on plants damaged 14 and 10 days after single and double herbivory, respectively. Our results suggest that temporal studies involving single versus multiple attacker situations are necessary to comprehend the role of induced plant responses in plant-herbivore interactions.
    Changes in frequencies of genes that enable Phyllotreta nemorum to utilize its host plant, Barbarea vulgaris, vary in magnitude and direction, as much within as between seasons
    Vermeer, K.M.C.A. ; Verbaarschot, P. ; Jong, P.W. de - \ 2012
    Entomologia Experimentalis et Applicata 144 (2012)1. - ISSN 0013-8703 - p. 37 - 44.
    flea beetle - conferring resistance - plutella-xylostella - diamondback moth - ssp arcuata - defenses - identification - coevolution - dynamics - genetics
    The interaction between the flea beetle, Phyllotreta nemorum L. (Coleoptera: Chrysomelidae), and its host plants is well suited to study the dynamics of a geographic mosaic of (co)evolution. The flea beetle can either be resistant or susceptible to the defense of one of its host plants, Barbarea vulgaris R.Br. G-type (Brassicaceae). Previous findings suggested that the frequency of resistant beetles on host plants other than the G-type of B. vulgaris had decreased over time within the period of 1999–2003. In 2008 and 2009 new sampling was performed to investigate whether or not this decrease in frequency of resistance of the flea beetles formed a continuing trend and whether or not the frequency of resistant beetles also varies within the year. The frequency of resistant beetles on different host plants was determined during the reproductive season of the flea beetles in both years. Overall, the frequencies of resistant beetles on B. vulgaris (G-type) remained close to 100%, as found before, but those on other host plants did not consistently decrease across the years, in contrast to what had been suggested. Furthermore, the repeated sampling revealed that the frequency of resistant beetles differed significantly within a season. The present data show that relative frequencies of different resistance phenotypes of P. nemorum on other host plants than B. vulgaris (G-type) are highly dynamic, both within and across years. Therefore, monitoring the changes in these resistance frequencies should involve season-wide sampling efforts. Although the monitoring in this study does not provide an explanation for the observed dynamics, we propose a testable scenario.
    Plant-mediated effects in the Brassicaceae on the performance and behaviour of parasitoids
    Gols, R. ; Harvey, J.A. - \ 2009
    Phytochemistry Reviews 8 (2009)1. - ISSN 1568-7767 - p. 187 - 206.
    diadegma-semiclausum hellen - natural enemy association - host-searching behavior - herbivore pieris-rapae - sawfly athalia-rosae - 3rd trophic level - mustard oil bomb - arabidopsis-thaliana - cotesia-glomerata - plutella-xylostella
    Direct and indirect plant defences are well studied, particularly in the Brassicaceae. Glucosinolates (GS) are secondary plant compounds characteristic in this plant family. They play an important role in defence against herbivores and pathogens. Insect herbivores that are specialists on brassicaceous plant species have evolved adaptations to excrete or detoxify GS. Other insect herbivores may even sequester GS and employ them as defence against their own antagonists, such as predators. Moreover, high levels of GS in the food plants of non-sequestering herbivores can negatively affect the growth and survival of their parasitoids. In addition to allelochemicals, plants produce volatile chemicals when damaged by herbivores. These herbivore induced plant volatiles (HIPV) have been demonstrated to play an important role in foraging behaviour of insect parasitoids. In addition, biosynthetic pathways involved in the production of HIPV are being unraveled using the model plant Arabidopsis thialiana. However, the majority of studies investigating the attractiveness of HIPV to parasitoids are based on experiments mainly using crop plant species in which defence traits may have changed through artificial selection. Field studies with both cultivated and wild crucifers, the latter in which defence traits are intact, are necessary to reveal the relative importance of direct and indirect plant defence strategies on parasitoid and plant fitness. Future research should also consider the potential conflict between direct and indirect plant defences when studying the evolution of plant defences against insect herbivory.
    Role of glucosinolates in insect-plant relationships and multitrophic interactions
    Hopkins, R.J. ; Dam, N.M. van; Loon, J.J.A. van - \ 2009
    Annual Review of Entomology 54 (2009). - ISSN 0066-4170 - p. 57 - 83.
    cabbage root fly - beetle psylliodes-chrysocephala - parasitoid diaeretiella-rapae - sawfly athalia-rosae - mustard oil bomb - oilseed rape - brassica-napus - arabidopsis-thaliana - plutella-xylostella - pieris-rapae
    Glucosinolates present classical examples of plant compounds affecting insect-plant interactions. They are found mainly in the family Brassicaceae, which includes several important crops. More than 120 different glucosinolates are known. The enzyme myrosinase, which is stored in specialized plant cells, converts glucosinolates to the toxic isothiocyanates. Insect herbivores may reduce the toxicity of glucosinolates and their products by excretion, detoxification, or behavioral adaptations. Glucosinolates also affect higher trophic levels, via reduced host or prey quality or because specialist herbivores may sequester glucosinolates for their own defense. There is substantial quantitative and qualitative variation between plant genotypes, tissues, and ontogenetic stages, which poses specific challenges to insect herbivores. Even though glucosinolates are constitutive defenses, their levels are influenced by abiotic and biotic factors including insect damage. Plant breeders may use knowledge on glucosinolates to increase insect resistance in Brassica crops. State-of-the-art techniques, such as mutant analysis and metabolomics, are necessary to identify the exact role of glucosinolates. Acronyms and Definitions Constitutive defense: defense characteristics that are always expressed in the plant Induced defense: induced responses that reduce the negative fitness consequences of an attack by a pest or pathogen Induced response: change in chemical compound levels after damage by herbivores Multitrophic interactions: interactions that involve more than two trophic levels in a food web Sequestration: the active accumulation of material as a means of protection against organisms from a higher trophic level Synomone: an allelochemical that elicits a response from which both the originator and receiver benefit Token (or sign) stimulus: a stimulus by which an animal distinguishes an important object
    Performance of specialist and generalist herbivores feeding on cabbage cultivars is not explained by glucosinolate profiles
    Poelman, E.H. ; Galiart, R.J.F.H. ; Raaijmakers, C.E. ; Loon, J.J.A. van; Dam, N.M. van - \ 2008
    Entomologia Experimentalis et Applicata 127 (2008)3. - ISSN 0013-8703 - p. 218 - 228.
    rape brassica-napus - oilseed rape - phytophagous insects - plutella-xylostella - wild populations - diamondback moth - pieris-rapae - resistance - mustard - responses
    Plants display a wide range of chemical defences that may differ in effectiveness against generalist and specialist insect herbivores. Host plant-specific secondary chemicals such as glucosinolates (GS) in Brassicaceae typically reduce the performance of generalist herbivores, whereas specialists have adaptations to detoxify these compounds. The concentration of glucosinolates may also alter upon herbivory, allowing the plant to tailor its response to specifically affect the performance of the attacking herbivore. We studied the performance of three Lepidoptera species, two specialists [Pieris rapae L. (Pieridae), Plutella xylostella L. (Yponomeutidae)] and one generalist [Mamestra brassicae L. (Noctuidae)], when feeding on eight cultivars of Brassica oleracea L. and a native congener (Brassica nigra L.) and related this to the GS content. We tested the hypotheses (i) that a generalist herbivore is more affected by high GS concentrations, and (ii) that generalist feeding has a stronger effect on GS levels. Although performance of the three herbivores was different on the B. oleracea cultivars, M. brassicae and P. xylostella had a similar ranking order of performance on the eight cultivars. In most of the cultivars, the concentration of indole GS was significantly higher after feeding by P. rapae or M. brassicae than after P. xylostella feeding. As a consequence, the total concentration of GS in the cultivars showed a different ranking order for each herbivore species. The generalist M. brassicae performed equally well as the specialist P. xylostella on cultivars with high concentrations of GS. Our findings suggest that secondary metabolites other than GSs or differences in nutrient levels affect performance of the species studied.
    Early season herbivore differentially affects plant defence responses to subsequently colonizing herbivores and their abundance in the field
    Poelman, E.H. ; Broekgaarden, C. ; Loon, J.J.A. van; Dicke, M. - \ 2008
    Molecular Ecology 17 (2008)14. - ISSN 0962-1083 - p. 3352 - 3365.
    tritrophic interaction webs - phytophagous insects - nicotiana-attenuata - induced resistance - diamondback moth - host-plant - interspecific interactions - plutella-xylostella - generalist herbivores - proteinase-inhibitors
    Induction of plant defences by early season herbivores can mediate interspecific herbivore competition. We have investigated plant-mediated competition between three herbivorous insects through studies at different levels of biological integration. We have addressed (i) gene expression; (ii) insect behaviour and performance under laboratory conditions; and (iii) population dynamics under field conditions. We studied the expression of genes encoding a trypsin inhibitor and genes that are involved in glucosinolate biosynthesis in response to early season herbivory by Pieris rapae caterpillars in Brassica oleracea plants. Furthermore, we studied the interaction of these transcriptional responses with responses to secondary herbivory by the two specialist herbivores, P. rapae and Plutella xylostella, and the generalist Mamestra brassicae. P. rapae-induced responses strongly interacted with plant responses to secondary herbivory. Sequential feeding by specialist herbivores resulted in enhanced or similar expression levels of defence-related genes compared to primary herbivory by specialists. Secondary herbivory by the generalist M. brassicae resulted in lower gene expression levels than in response to primary herbivory by this generalist. Larval performance of both specialist and generalist herbivores was negatively affected by P. rapae-induced plant responses. However, in the field the specialist P. xylostella was more abundant on P. rapae-induced plants and preferred these plants over undamaged plants in oviposition experiments. In contrast, the generalist M. brassicae was more abundant on control plants and preferred undamaged plants for oviposition. P. rapae did not discriminate between plants damaged by conspecifics or undamaged plants. Our study shows that early season herbivory differentially affects transcriptional responses involved in plant defence to secondary herbivores and their population development dependent upon their degree of host plant specialization.
    Barbarea vulgaris glucosinolate phenotypes differentially affect performance and preference of two different species of Lepidopteran herbivores
    Leur, H. van; Vet, L.E.M. ; Putten, W.H. van der; Dam, N.M. van - \ 2008
    Journal of Chemical Ecology 34 (2008)2. - ISSN 0098-0331 - p. 121 - 131.
    host-plant selection - p-napi-oleracea - plutella-xylostella - diamondback moth - 2-phenylethyl glucosinolate - oviposition behavior - pieris-rapae - brassicae lepidoptera - arabidopsis-thaliana - feeding deterrent
    The composition of secondary metabolites and the nutritional value of a plant both determine herbivore preference and performance. The genetically determined glucosinolate pattern of Barbarea vulgaris can be dominated by either glucobarbarin (BAR-type) or by gluconasturtiin (NAS-type). Because of the structural differences, these glucosinolates may have different effects on herbivores. We compared the two Barbarea chemotypes with regards to the preference and performance of two lepidopteran herbivores, using Mamestra brassicae as a generalist and Pieris rapae as a specialist. The generalist and specialist herbivores did not prefer either chemotype for oviposition. However, larvae of the generalist M. brassicae preferred to feed and performed best on NAS-type plants. On NAS-type plants, 100% of the M. brassicae larvae survived while growing exponentially, whereas on BAR-type plants, M. brassicae larvae showed little growth and a mortality of 37.5%. In contrast to M. brassicae, the larval preference and performance of the specialist P. rapae was unaffected by plant chemotype. Total levels of glucosinolates, water soluble sugars, and amino acids of B. vulgaris could not explain the poor preference and performance of M. brassicae on BAR-type plants. Our results suggest that difference in glucosinolate chemical structure is responsible for the differential effects of the B. vulgaris chemotypes on the generalist herbivore.
    Performance of generalist and specialist herbivores and their endoparasitoids differs on cultivated and wild Brassica populations
    Gols, G.J.Z. ; Bukovinszky, T. ; Dam, N.M. van; Dicke, M. ; Bullock, J.M. ; Harvey, J.A. - \ 2008
    Journal of Chemical Ecology 34 (2008)2. - ISSN 0098-0331 - p. 132 - 143.
    oilseed rape - plutella-xylostella - host-plant - glucosinolate content - cotesia-congregata - induced responses - natural enemies - trophic levels - pieris-rapae - oleracea
    Through artificial selection, domesticated plants often contain modified levels of primary and secondary metabolites compared to their wild progenitors. It is hypothesized that the changed chemistry of cultivated plants will affect the performance of insects associated with these plants. In this paper, the development of several specialist and generalist herbivores and their endoparasitoids were compared when reared on a wild and cultivated population of cabbage, Brassica oleracea, and a recently established feral Brassica species. Irrespective of insect species or the degree of dietary specialization, herbivores and parasitoids developed most poorly on the wild population. For the specialists, plant population influenced only development time and adult body mass, whereas for the generalists, plant populations also affected egg-to-adult survival. Two parasitoid species, a generalist (Diadegma fenestrale) and a specialist (D. semiclausum), were reared from the same host (Plutella xylostella). Performance of D. semiclausum was closely linked to that of its host, whereas the correlation between survival of D. fenestrale and host performance was less clear. Plants in the Brassicaceae characteristically produce defense-related glucosinolates (GS). Levels of GS in leaves of undamaged plants were significantly higher in plants from the wild population than from the domesticated populations. Moreover, total GS concentrations increased significantly in wild plants after herbivory, but not in domesticated or feral plants. The results of this study reveal that a cabbage cultivar and plants from a wild cabbage population exhibit significant differences in quality in terms of their effects on the growth and development of insect herbivores and their natural enemies. Although cultivated plants have proved to be model systems in agroecology, we argue that some caution should be applied to evolutionary explanations derived from studies on domesticated plants, unless some knowledge exists on the history of the system under investigation.
    Flower vs. leaf feeding by Pieris brassicae: Glucosinolate-rich flower tissues are preferred and sustain higher growth rate
    Smallegange, R.C. ; Loon, J.J.A. van; Blatt, S.E. ; Harvey, J.A. ; Agerbirk, N. ; Dicke, M. - \ 2007
    Journal of Chemical Ecology 33 (2007)10. - ISSN 0098-0331 - p. 1831 - 1844.
    host-plant - plutella-xylostella - seasonal-variation - chemical defense - foliar herbivory - cinnabar moth - wild radish - myrosinase - fitness - rapae
    Interactions between butterflies and caterpillars in the genus Pieris and plants in the family Brassicaceae are among the best explored in the field of insect-plant biology. However, we report here for the first time that Pieris brassicae, commonly assumed to be a typical folivore, actually prefers to feed on flowers of three Brassica nigra genotypes rather than on their leaves. First- and second-instar caterpillars were observed to feed primarily on leaves, whereas late second and early third instars migrated via the small leaves of the flower branches to the flower buds and flowers. Once flower feeding began, no further leaf feeding was observed. We investigated growth rates of caterpillars having access exclusively to either leaves of flowering plants or flowers. In addition, we analyzed glucosinolate concentrations in leaves and flowers. Late-second- and early-third-instar P. brassicae caterpillars moved upward into the inflorescences of B. nigra and fed on buds and flowers until the end of the final (fifth) instar, after which they entered into the wandering stage, leaving the plant in search of a pupation site. Flower feeding sustained a significantly higher growth rate than leaf feeding. Flowers contained levels of glucosinolates up to five times higher than those of leaves. Five glucosinolates were identified: the aliphatic sinigrin, the aromatic phenyethylglucosinolate, and three indole glucosinolates: glucobrassicin, 4-methoxyglucobrassicin, and 4-hydroxyglucobrassicin. Tissue type and genotype were the most important factors affecting levels of identified glucosinolates. Sinigrin was by far the most abundant compound in all three genotypes. Sinigrin, 4-hydroxyglucobrassicin, and phenylethylglucosinolate were present at significantly higher levels in flowers than in leaves. In response to caterpillar feeding, sinigrin levels in both leaves and flowers were significantly higher than in undamaged plants, whereas 4-hydroxyglucobrassicin leaf levels were lower. Our results show that feeding on flower tissues, containing higher concentrations of glucosinolates, provides P. brassicae with a nutritional benefit in terms of higher growth rate. This preference appears to be in contrast to published negative effects of volatile glucosinolate breakdown products on the closely related Pieris rapae.
    Temporal changes affect plant chemistry and tritrophic interactions
    Gols, R. ; Raaijmakers, C.E. ; Dam, N.M. van; Dicke, M. ; Bukovinszky, T. ; Harvey, J.A. - \ 2007
    Basic and Applied Ecology 8 (2007)5. - ISSN 1439-1791 - p. 421 - 433.
    glucosinolate content - plutella-xylostella - diamondback moth - seasonal-changes - abiotic factors - trophic levels - pieris-rapae - herbivore - host - lepidoptera
    In nature, individuals of short-lived plant species (e.g. annuals, biennials) may grow at different times during the growing season. These plants are therefore exposed to different season-related conditions such as light and temperature, which in turn may have consequences for primary and secondary chemistry of the plant. Despite this, many studies examining plant¿consumer interactions are performed in single replicates, which may thus ignore temporal variation in the expression of phenotypic plant traits that affect multitrophic interactions. In the present study, we demonstrated that even under strictly controlled conditions in a greenhouse, secondary plant chemistry changes dramatically in plants growing at different times in a single year, i.e. July, August and November. Glucosinolate (GS) contents in herbivore-damaged leaves of two different crucifer species, Brassica oleracea and Sinapis alba were higher in the August and November replicates than in the July replicate and GS concentrations were 10¿25 times higher in S. alba than in B. oleracea. The development of a specialist herbivore, Plutella xylostella, also varied significantly over the three replicates. Larvae of P. xylostella that had fed upon either S. alba or B. oleracea, attained the largest biomass and had the fastest development rate in the November replicate. Female P. xylostella moths grew larger on S. alba than on B. oleracea, whereas male biomass was not significantly affected by host-plant species. Plant species, but not season also affected performance of the endoparasitoid, Diadegma semiclausum. Similar to the performance of host females, parasitoid males developed faster and attained the highest biomass when attacking P. xylostella larvae feeding on S. alba. Most importantly, the performance of the herbivore and its parasitoid only appeared to partially conform to levels of GS in damaged leaves, indicating that there is a complex of factors involved in determining the effects of plant quality on higher trophic levels.
    Development of an insect herbivore and its pupal parasitoid reflect differences in direct plant defense
    Harvey, J.A. ; Gols, R. ; Wagenaar, R. ; Bezemer, T.M. - \ 2007
    Journal of Chemical Ecology 33 (2007)8. - ISSN 0098-0331 - p. 1556 - 1569.
    4 trophic levels - host-plant - specialist herbivore - phytophagous insects - plutella-xylostella - brassica-oleracea - wild populations - trichoplusia-ni - manduca-sexta - pieris-rapae
    In nature, plants defend themselves by production of allelochemicals that are toxic to herbivores. There may be considerable genetic variation in the expression of chemical defenses because of various selection pressures. In this study, we examined the development of the small cabbage butterfly, Pieris rapae, and its gregarious pupal ectoparasitoid, Pteromalus puparum, when reared on three wild populations (Kimmeridge, Old Harry, Winspit) of cabbage, Brassica oleracea, and a Brussels sprout cultivar. Wild plant populations were obtained from seeds of plants that grow naturally along the south coast of Dorset, England. Significant differences in concentrations of allelochemicals (glucosinolates) were found in leaves of plants damaged by P. rapae. Total glucosinolate concentrations in Winspit plants, the population with the highest total glucosinolate concentration, were approximately four times higher than in the cultivar, the strain with the lowest total glucosinolate concentration. Pupal mass of P. rapae and adult body mass of Pt. puparum were highest when reared on the cultivar and lowest when developing on Kimmeridge plants, the wild strain with the lowest total glucosinolate concentration. Development of male parasitoids was also more negatively affected than female parasitoids. Our results reveal that plant quality, at least for the development of 'adapted' oligophagous herbivores, such as P. rapae, is not based on total glucosinolate content. The only glucosinolate compound that corresponded with the performance of P. rapae was the indole glucosinolate, neoglucobrassicin. Our results show that performance of ectoparasitoids may closely reflect constraints on the development of the host.
    Root herbivores influence the behaviour of an aboveground parasitoid through changes in plant-volatile signals
    Soler, R. ; Harvey, J.A. ; Kamp, A.F.D. ; Vet, L.E.M. ; Putten, W.H. van der; Dam, N.M. van; Stuefer, J.F. ; Gols, R. ; Hordijk, C.A. ; Bezemer, T.M. - \ 2007
    Oikos 116 (2007)3. - ISSN 0030-1299 - p. 367 - 376.
    cotesia-glomerata - natural enemies - evolutionary context - plutella-xylostella - insect parasitoids - infochemical use - trophic levels - host-plant - performance - responses
    It is widely reported that plants emit volatile compounds when they are attacked by herbivorous insects, which may be used by parasitoids and predators to locate their host or prey. The study of herbivore-induced plant volatiles and their role in mediating interactions between plants, herbivores and their natural enemies have been primarily based on aboveground systems, generally ignoring the potential interactions between above and belowground infochemical- and food webs. This study examines whether herbivory by Delia radicum feeding on roots of Brassica nigra (black mustard) affects the behaviour of Cotesia glomerata, a parasitoid of the leaf herbivore Pieris brassicae, mediated by changes in plant volatiles. In a semi-field experiment with root-damaged and root-undamaged plants C. glomerata prefers to oviposit in hosts feeding on root-undamaged plants. In addition, in a flight-cage experiment the parasitoid also prefers to search for hosts on plants without root herbivores. Plants exposed to root herbivory were shown to emit a volatile blend characterized by high levels of specific sulphur volatile compounds, which are reported to be highly toxic for insects, combined with low levels of several compounds, i.e. beta-farnesene, reported to act as attractants for herbivorous and carnivorous insects. Our results provide evidence that the foraging behaviour of a parasitoid of an aboveground herbivore can be influenced by belowground herbivores through changes in the plant volatile blend. Such indirect interactions may have profound consequences for the evolution of host selection behaviour in parasitoids, and may play an important role in the structuring and functioning of communities.
    Impact of botanical pesticides derived from Melia azedarach an Azadirachta indica plants on the emission of volatiles that attract parasitoids of the diamondback moth to cabbage
    Charleston, D.S. ; Gols, R. ; Hordijk, K.A. ; Kfir, R. ; Vet, L.E.M. ; Dicke, M. - \ 2006
    Journal of Chemical Ecology 32 (2006)2. - ISSN 0098-0331 - p. 325 - 349.
    herbivore-induced terpenoids - brussels-sprouts plants - lima-bean leaves - jasmonic acid - cotesia-glomerata - natural enemies - plutella-xylostella - foraging behavior - spider-mites - c-rubecula
    Herbivorous and carnivorous arthropods use chemical information from plants during foraging. Aqueous leaf extracts from the syringa tree Melia azedarach and commercial formulations from the neem tree Azadirachta indica, Neemix 4.5®, were investigated for their impact on the flight response of two parasitoids, Cotesia plutellae and Diadromus collaris. Cotesia plutellae was attracted only to Plutella xylostella-infested cabbage plants in a wind tunnel after an oviposition experience. Female C. plutellae did not distinguish between P. xylostella-infested cabbage plants treated with neem and control P. xylostella-infested plants. However, females preferred infested cabbage plants that had been treated with syringa extract to control infested plants. Syringa extract on filter paper did not attract C. plutellae. This suggests that an interaction between the plant and the syringa extract enhances parasitoid attraction. Diadromus collaris was not attracted to cabbage plants in a wind tunnel and did not distinguish between caterpillar-damaged and undamaged cabbage plants. Headspace analysis revealed 49 compounds in both control cabbage plants and cabbage plants that had been treated with the syringa extract. Among these are alcohols, aldehydes, ketones, esters, terpenoids, sulfides, and an isothiocyanate. Cabbage plants that had been treated with the syringa extract emitted larger quantities of volatiles, and these increased quantities were not derived from the syringa extract. Therefore, the syringa extract seemed to induce the emission of cabbage volatiles. To our knowledge, this is the first example of a plant extract inducing the emission of plant volatiles in another plant. This interesting phenomenon likely explains the preference of C. plutellae parasitoids for cabbage plants that have been treated with syringa extracts
    AFLP markers for the R-gene in the flea beetle, Phyllotreta nemorum, conferring resistance to defenses in Barbarea vulgaris
    Breuker, C.J. ; Victoir, K. ; Jong, P.W. de; Meijden, E. van der; Brakefield, P.M. ; Vrieling, K. - \ 2005
    Journal of Insect Science 5 (2005). - ISSN 1536-2442 - p. 38 - 38.
    atypical host-plant - plutella-xylostella - diamondback moth - lucilia-cuprina - asymmetry phenotype - diazinon resistance - culex-pipiens - identification - brassicaceae - specificity
    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 "Kværkeby" are described, and a genetic linkage map around this particular R-gene is constructed, using the technique of AFLP (Amplified Fragment Length Polymorphism)
    Variation in plant volatiles and attraction of the parasitoid Diadegma semiclausum (Hellén)
    Bukovinszky, T. ; Gols, R. ; Posthumus, M.A. ; Vet, L.E.M. ; Lenteren, J.C. van - \ 2005
    Journal of Chemical Ecology 31 (2005)3. - ISSN 0098-0331 - p. 461 - 480.
    enemy-free space - diaeretiella-rapae hymenoptera - brussels-sprouts plants - plutella-xylostella - host-plant - foraging behavior - diamondback moth - natural enemies - cabbage plants - rubecula hymenoptera
    Differences in allelochemistry of plants may influence their ability to attract parasitoids.We studied responses of Diadegma semiclausum (Hellén), a parasitoid of the diamondback moth (Plutella xylostella L.), to inter- and intraspecific variation in odor blends of crucifers and a non-crucifer species. Uninfested Brussels sprout (Brassica oleracea L. gemmifera), white mustard (Sinapis alba L.), a feral Brassica oleracea, and malting barley (Hordeum vulgare L.) were compared for their attractivity to D. semiclausum in a Y-tube bioassay. Odors from all plants were more attractive to the parasitoid than clean air. However, tested against each other, parasitoids preferred the volatile blend from the three cruciferous species over that of malting barley.Wasps also discriminated between uninfested crucifers: mustard was as attractive as feral B. oleracea, and both were more attractive than Brussels sprout. Attractivity of uninfested plants was compared with that of plants infested by larvae of the host P. xylostella. Host-infested mustard and Brussels sprout were more attractive than uninfested conspecifics. Interestingly, the volatile blends of uninfested white mustard and infested Brussels sprout were equally attractive.We also compared the volatile composition of different plant sources by collecting headspace samples and analysing them with GC-MS. Similarities of volatile profiles were determined by hierarchic clustering and non-metric scaling based on the Horn-index. Due to the absence of several compounds in its blend, the volatile profile of barley showed dissimilarities from blends of crucifers. The odor profile of white mustard was distinctly different from the two Brassicaceae.Feral Brassica oleracea odor profile was different from infested Brussels sprout, but showed overlap with uninfested Brussels sprout. Odor blends from infested and uninfested Brussels sprout were similar, and mainly quantitative differences were found. D. semiclausum appears to discriminate based on subtle differences in volatile composition of odor blends from infested and uninfested plants
    Impact of botanical pesticides derived from Melia azedarach and Azadirachta indica on the biology of two parasitoid species of the diamondback moth
    Charleston, D.S. ; Kfir, R. ; Dicke, M. ; Vet, L.E.M. - \ 2005
    Biological Control 33 (2005)2. - ISSN 1049-9644 - p. 131 - 142.
    size-fitness hypothesis - plutella-xylostella - cotesia-plutellae - sex-ratio - diadromus-collaris - natural enemies - host-size - bt plants - hymenoptera - behavior
    The effect of two botanical pesticides was tested on two species of parasitoids, Cotesia plutellae and Diadromus collaris. Aqueous leaf extracts from the syringa tree, Melia azedarach and commercial formulations from the neem tree, Azadirachta indica, Neemix 4.5 were investigated in the laboratory and in a glasshouse. No direct negative effect was recorded on the longevity of the parasitoid species. However, hind tibia length was found to be significantly shorter in male C. plutellae that emerged from Plutella xylostella that had been exposed to syringa extracts. Whether this negatively affects the fitness of male C. plutellae remains unknown. The impact of the botanical extracts on the fitness of D. collaris could not be investigated because the pesticides resulted in a high mortality of P. xylostella hosts. In the glasshouse a significantly higher proportion of P. xylostella were parasitised by C. plutellae on plants treated with botanical pesticides than on the control plants. However, there were no significant differences between the treatments for the proportion of P. xylostella parasitised by D. collaris. Results indicate that these botanical pesticides have the potential to be combined with biological control programs for P. xylostella
    Reduced foraging efficiency of a parasitoid under habitat complexity: implications for population stability and species coexistence
    Gols, R. ; Bukovinszky, T. ; Hemerik, L. ; Harvey, J.A. ; Lenteren, J.C. van; Vet, L.E.M. - \ 2005
    Journal of Animal Ecology 74 (2005)6. - ISSN 0021-8790 - p. 1059 - 1068.
    diadegma-semiclausum hellen - enemy-free space - insect parasitoids - natural enemies - searching efficiency - plutella-xylostella - diamondback moth - plant volatiles - trophic levels - herbivore
    1. Habitat complexity may stabilize interactions among species of different trophic levels by providing refuges to organisms of lower trophic levels. 2. Searching behaviour of the parasitoid, Diadegma semiclausum, was followed in different semifield set-ups, a low and high-density monoculture of Brassica oleracea and two intercrops, B. oleracea with Sinapis alba (also a member of the Brassicaceae) and B. oleracea with Hordeum vulgare (Poaceae). 3. When a low-density monocrop of B. oleracea was compared with a high-density monocrop, no differences were found in the ability of the female wasps to locate a host-infested plant, B. oleracea, infested with Plutella xylostella that was placed in the centre of the set-up. 4. The efficiency of the parasitoid to locate the host-infested plant was differentially affected by the species composition of the vegetation. Wasps entered the Sinapis-Brassica set-up faster, but took more time to find the host-infested plant than in the Hordeum-Brassica set-up. 5. The horizontal arrangement, i.e. by mixing S. alba or H. vulgare with, or placing them as rows between B. oleracea, did not affect host-finding efficiency. 6. Plant height did influence host finding. Wasps found the host-infested plants earlier in the set-up with short Sinapis plants compared with tall Sinapis plants. 7. Once the wasps had landed on the host-infested plant, the surrounding vegetation did not affect time needed to parasitize five consecutive hosts on the same infested plant, regardless of the composition or horizontal/vertical arrangement of the set-up. 8. Chemical and structural refuges in complex landscapes may play an important role in the persistence of this system through dampening oscillations of parasitoid and host populations
    Bacillus thuringiensis Cry1Ca-resistant Spodoptera exigua lacks expression of one of four Aminopeptidase N genes
    Herrero, S. ; Gechev, T. ; Bakker, P.L. ; Moar, W. ; Maagd, R.A. de - \ 2005
    BMC Genomics 6 (2005). - ISSN 1471-2164 - p. 96 - 96.
    brush-border membrane - delta-endotoxin - manduca-sexta - bombyx-mori - heliothis-virescens - plutella-xylostella - molecular-cloning - toxin receptor - cry1a toxins - midgut
    BACKGROUND: Insecticidal toxins from Bacillus thuringiensis bind to receptors on midgut epithelial cells of susceptible insect larvae. Aminopeptidases N (APNs) from several insect species have been shown to be putative receptors for these toxins. Here we report the cloning and expression analysis of four APN cDNAs from Spodoptera exigua. RESULTS: Suppression Subtractive Hybridization (SSH) was used to construct cDNA libraries of genes that are up- and down-regulated in the midgut of last instar larvae of beet armyworm, S. exigua exposed to B. thuringiensis Cry1Ca toxin. Among the clones from the SSH libraries, cDNA fragments coding for two different APNs were obtained (APN2 and APN4). A similar procedure was employed to compare mRNA differences between susceptible and Cry1Ca resistant S. exigua. Among the clones from this last comparison, cDNA fragments belonging to a third APN (APN1) were detected. Using sequences obtained from the three APN cDNA fragments and degenerate primers for a fourth APN (APN3), the full length sequences of four S. exigua APN cDNAs were obtained. Northern blot analysis of expression of the four APNs showed complete absence of APN1 expression in the resistant insects, while the other three APNs showed similar expression levels in the resistant and susceptible insects. CONCLUSIONS: We have cloned and characterized four different midgut APN cDNAs from S. exigua. Expression analysis revealed the lack of expression of one of these APNs in the larvae of a Cry1Ca-resistant colony. Combined with previous evidence that shows the importance of APN in the mode of action of B. thuringiensis toxins, these results suggest that the lack of APN1 expression plays a role in the resistance to Cry1Ca in this S. exigua colony
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