- ALTERRA Wageningen UR (1)
- Biometris (WU MAT) (1)
- CE - Vegetation and Landscape Ecology (1)
- Crop and Weed Ecology (1)
- Environmental Economics and Natural Resources (1)
- Environmental Economics and Natural Resources Group (1)
- MGS (1)
- Mathematical and Statistical Methods - Biometris (1)
- Resource Ecology (1)
- Wageningen Environmental Research (1)
- Wageningen UR Greenhouse Horticulture (1)
- R. Gols (1)
- L. Hemerik (1)
- E.C. Ierland van (1)
- A. Janssen (1)
- O. Kostenko (1)
- A.T. Kuiters (1)
- F. Langevelde van (1)
- J.C. Lenteren van (1)
- H. Leur van (1)
- Yehua Li (1)
- D. Lucas Gomes Marques Barbosa (1)
- R. Maanen van (1)
- G.J. Messelink (1)
- N.P.D. Pangesti (1)
- E.H. Poelman (1)
- H.H.T. Prins (1)
- M. Rijk de (1)
- M.W. Sabelis (1)
- R. Soler Gamborena (3)
- J.H. Talsma (1)
- W. Werf van der (1)
- F. Zhu (1)
Plant responses to multiple herbivory : phenotypic changes and their ecological consequences
Li, Yehua - \ 2016
Wageningen University. Promotor(en): Marcel Dicke, co-promotor(en): Rieta Gols. - Wageningen : Wageningen University - ISBN 9789462578043 - 165
brassica oleracea - brevicoryne brassicae - aphidoidea - caterpillars - insect pests - pest resistance - defence mechanisms - phenotypes - insect plant relations - parasitoids - natural enemies - herbivore induced plant volatiles - plant-herbivore interactions - genetic variation - rupsen - insectenplagen - plaagresistentie - verdedigingsmechanismen - fenotypen - insect-plant relaties - parasitoïden - natuurlijke vijanden - herbivoor-geinduceerde plantengeuren - plant-herbivoor relaties - genetische variatie
This thesis explores whether aphid-infestation interferes with the plant response to chewing herbivores and whether this impacts performance and behaviour of individual chewing insect herbivores and their natural enemies, as well as the entire insect community. I investigated this using three wild cabbage populations (Brassica oleracea) that are known to differ in inducible secondary chemistry, to reveal whether patterns were consistent.
A literature review on recent developments in the field of plant interactions with multiple herbivores (Chapter 2) addressed how plant traits mediate interactions with various species of the associated insect community and their dynamics. In addition, the mechanisms underlying phenotypic changes in response to different herbivores were discussed from the expression of defence-related genes, phytohormones and secondary metabolites in plants to their effects on the performance and behaviour of individual insects as well as the entire insect community. In Chapter 3, I investigated the effects of early-season infestation by the aphid Brevicoryne brassicae on the composition and dynamics of the entire insect community throughout the season in a garden experiment replicated in two consecutive years. Aphid infestation in the early season only affected a subset of the community, i.e. the natural enemies of aphids, but not the chewing herbivores and their natural enemies. Moreover, the effects were only significant in the first half (June & July), but waned in the second half of the season (August & September). The effect of aphid infestation on the community of natural enemies also varied among the cabbage populations. Chapter 4 investigated the effects of aphid infestation on plant direct defences against chewing herbivores in laboratory experiments by comparing the performance of chewing herbivores and their parasitoids on aphid-infested and aphid-free plants. The performance of the specialist herbivore Plutella xylostella and its parasitoid Diadegma semiclausum was better on plants infested with aphids than on aphid-free plants, whereas the performance of the generalist herbivore Mamestra brassicae and its parasitoid Microplitis mediator was not affected by aphid infestation. These results suggest that aphid induced changes in plant traits may differentially affect the performance of leaf-chewing herbivore species attacking the same host plant, and also varied among the cabbage populations. Chapter 5 examined the effects of B. brassicae aphid infestation on plant indirect defences against chewing herbivores. In a two-choice olfactometer bioassay, preference behaviour for volatiles emitted by plants infested with hosts alone and those emitted by plants infested with aphids and hosts was compared for D. semiclausum and M mediator, larval endoparasitoids of caterpillars of P. xylostella and M. brassicae, respectively. In addition, the headspace volatiles emitted by host-infested and dually-infested plants were collected and analyzed. Co-infestation with aphids differentially affected volatile-mediated foraging behaviour of the two parasitoid species in an infestation period-dependent manner. Diadegma semiclausum preferred dually infested plants over host-infested plants when aphids infested the plants for a short time period, i.e. 7 days, but the volatile preference of D. semiclausum was reversed when aphid infestation was extended to 14 days. In contrast, M. mediator consistently preferred volatiles emitted by the dually-infested plants over those emitted by host-infested plants. The patterns of preference behaviour of the two wasp species were consistent across the three cabbage populations. Interestingly, the emission rate of most volatile compounds was reduced in plants dually-infested with caterpillars and aphids compared to singly-infested with caterpillars. This study showed that aphid infestation increased plant indirect defences against caterpillars, but depended on the aphid infestation period and specific caterpillar-parasitoid association. We hypothesized a negative interference of aphid infestation on plant defences against chewing herbivores based on previously reported SA-JA antagonism. In Chapter 6, we assessed the activation of SA and JA signaling pathways in plants infested by both aphids (B. brassicae) and various caterpillar species (P. xylostella, M. brassicae and Pieris brassicae) in different time sequences by quantifying transcription levels of the SA- and JA-responsive marker genes, PR-1 and LOX respectively. The results did not provide support for SA-JA antagonism. Compared to single infestation with each of the herbivore species, dual infestation with aphid and caterpillars had no interactive effects on the transcription levels of the SA- and JA-responsive maker genes, regardless of the temporal sequence of aphid and caterpillar attack, or the identity of the attacking caterpillar species.
The findings of this thesis contribute to our understanding of plant responses to herbivory by insect species belonging to different feeding guilds and their ecological effects on other associated community members. Aphid infestation may interfere with plant direct and indirect defences against leaf-chewing herbivores at the individual species level, but the effects are species-specific and also depend on the infestation period of aphids. Early-season aphid infestation may further affect the composition of the insect community, but the effect is smaller influencing only a subset of the community compared to early infestation by chewing herbivores. The molecular mechanism underlying plant responses to both phloem-feeding and leaf-chewing herbivores are complex and require the investigation of a range of genes involved in JA- and SA-mediated defence signal transduction. Plant interact with multiple herbivores at different levels of biological organization ranging from the subcellular level to the individual and the community level, and an integrated multidisciplinary approach is required to investigate plant-insect interactions.
The importance of phenology in studies of plant-herbivore-parasitoid interactions
Fei, Minghui - \ 2016
Wageningen University. Promotor(en): Louise Vet; J.A. Harvey; Rieta Gols. - Wageningen : Wageningen University - ISBN 9789462576551 - 170 p.
016-3952 - phenology - plant-herbivore interactions - parasitoids - interactions - annuals - insects - pieris brassicae - cotesia glomerata - brassicaceae - host plants - fenologie - plant-herbivoor relaties - parasitoïden - interacties - eenjarigen - insecten - waardplanten
Foraging behaviour of parasitoids in multi-herbivore communities
Rijk, M. de - \ 2016
Wageningen University. Promotor(en): Marcel Dicke, co-promotor(en): Erik Poelman. - Wageningen : Wageningen University - ISBN 9789462576377 - 217 p.
016-3931 - parasitoids - parasitoid wasps - feeding behaviour - plant-herbivore interactions - hosts - host parasite relationships - host preferences - host-seeking behaviour - cotesia glomerata - pieris brassicae - brassica oleracea - parasitoïden - sluipwespen - voedingsgedrag - plant-herbivoor relaties - gastheren (dieren, mensen, planten) - gastheer parasiet relaties - gastheerpreferenties - gedrag bij zoeken van een gastheer
Foraging behaviour of parasitoids in multi-herbivore communities
Parasitic wasps, or parasitoids, use herbivore-induced plant volatiles and infochemicals produced directly by the herbivore to locate their herbivorous hosts. This process could be interrupted by the presence of herbivores that are not suitable for the development of parasitoid offspring. These non-host herbivores could affect the behaviour of parasitoids both when parasitoids are foraging for host-infested plants by using plant volatiles and when parasitoids are foraging for hosts on the plant by using herbivore infochemicals.
The aim of this thesis was to study the impact of non-host presence on the parasitoid-host-food plant complex of the parasitoid Cotesia glomerata with its host caterpillar Pieris brassicae and a monoculture of the cultivated plant Brassica oleracea. To study the influence of non-hosts on the plant-volatile-based searching behaviour of the parasitoid, a wind-tunnel set-up in the laboratory was used. In this set-up, the parasitoids were given a choice between two plants or between the leaves of one plant. The plant/leaf on which the parasitoid landed was considered the preferred plant/leaf. A second laboratory set-up was used to study the influence of non-host herbivores on the host-infochemical-based searching behaviour of the parasitoid. In this on-plant experiment, the behaviour of the parasitoid was observed after landing on the plant. The influence of non-hosts on the combination of plant-volatile-based and host-infochemical-based searching, i.e. the total foraging efficiency of the parasitoid, was investigated using an outdoor tent set-up in an agricultural field. In this semi-field experiment, parasitoids were allowed to parasitize their hosts in a non-host environment for one to three days.
This thesis firstly shows that the feeding guild of non-host herbivores influenced the foraging behaviour of C. glomerata. Leaf-chewing non-hosts negatively impacted the plant-volatile-based searching behaviour of the parasitoid, whereas phloem-feeding non-hosts positively impacted the host-infochemical-based searching. The resulting host-finding efficiency was in general positively affected by phloem-feeding non-hosts. Secondly, the position of host and non-host herbivores on the plant affected the plant-volatile-based and the host-infochemical-based foraging behaviour of the parasitoid, but not the host-finding efficiency. An unnatural distribution of herbivores over the plant (host feeding on old leaf, non-host feeding on young leaf), negatively affected the choice of the parasitoid for a leaf to land on, i.e. the parasitoid more often landed on the non-host infested leaf. Combined feeding by the host and non-host on one leaf positively affected the number of hosts parasitized on that plant compared with the number of hosts parasitized when herbivores were separated. However, the parasitoid was able to compensate for these effects as a result of which the foraging efficiency was unaltered. Thirdly, the density of non-hosts did influence the plant-volatile-based searching of the parasitoid. A high non-host density negatively affected parasitoid preference for host-infested plants. However, the host-infochemical-based foraging and the total foraging efficiency remained unaffected. Fourthly, rather than the species diversity, the species identity of non-host herbivores had an influence on parasitoid host-infochemical-based searching. One of the tested non-host species negatively affected the behaviour of the parasitoid when searching on the plant. However, neither non-host species identity nor diversity affected plant-volatile-based searching of the parasitoid. Fifthly, this thesis investigated if a parasitoid could learn to associate non-host cues with the presence of hosts and if the parasitoid changed the parasitization preference accordingly. After receiving a learning experience, the parasitoid showed an altered landing preference for infested plants according to the learned cues. However, in an outdoor tent set-up, the parasitoid did not show an altered parasitization preference.
The results of this thesis show that non-host herbivore traits can affect the different phases of parasitoid foraging either positively, negatively or neutrally. The non-host effect on the total foraging efficiency is not necessarily a result of the sum of the effects on the first and the second foraging phase. In fact, the results of two out of three outdoor-tent experiments that investigated the foraging efficiency of the parasitoid showed no non-host effect, while the separate foraging phases were affected by non-host presence.
It is concluded that the foraging efficiency of the parasitoid C. glomerata when searching for its host P. brassicae is not strongly affected by non-host herbivore presence. The use of herbivore-induced plant volatiles by C. glomerata during this foraging process is not interrupted by non-host herbivores. It is advised to consider all phases of the foraging process in studies of parasitoid foraging behaviour, preferably in one experiment that covers the whole searching process. Altogether, this thesis gives a clear and comprehensive overview of the impact of non-host presence on a parasitoid-host-food plant complex and it thereby contributes to the fundamental knowledge of insect foraging in a multi-herbivore context.
Host location by hyperparasitoids: an ecogenomic approach
Zhu, F. - \ 2015
Wageningen University. Promotor(en): Marcel Dicke, co-promotor(en): Erik Poelman. - Wageningen : Wageningen University - ISBN 9789462574441 - 191
insect-plant relaties - insectenplagen - herbivorie - parasitoïden - planten - verdedigingsmechanismen - symbionten - plant-herbivoor relaties - herbivoor-geinduceerde plantengeuren - hyperparasitoïden - insect plant relations - insect pests - herbivory - parasitoids - plants - defence mechanisms - symbionts - plant-herbivore interactions - herbivore induced plant volatiles - hyperparasitoids
It is fascinating that our ecological systems are structured by both direct and indirect species interactions. In terrestrial ecosystems, plants interact with many species of insects that include both harmful herbivores and beneficial natural enemies of herbivores. During the last 30 years, substantial progress has been made in different plant-insect systems regarding plant trait-mediated species interactions in a tritrophic context. However, plant-based food webs generally consist of more than three trophic levels. For example, hyperparasitoids are parasitic wasps at the fourth trophic level within the plant-associated insect community. They parasitize larvae or pupae of primary parasitoids that are broadly used in biological pest control programmes. Surprisingly, the cues that hyperparasitoids use for host location have remained largely unknown.
The studies presented in this thesis aimed to investigate the cues that are used by hyperparasitoids in host location using an ecogenomic approach that combines metabolomic, transcriptomic and proteomic tools with behavioural studies and field experiments. In addition, we addressed the role of herbivore-associated organisms in plant-mediated indirect species interactions. A naturally existing study system of the Brassica oleracea plant-based food web, including four trophic levels was used. In this system, the two herbivorous insect species, Pieris brassicae and P. rapae, are specialists on Brassica plants. The plants emit herbivore-induced plant volatiles (HIPVs) in response to Pieris caterpillar feeding damage which results in attraction of natural enemies of the herbivores, i.e. Cotesia wasps. These parasitic wasps, in turn, are attacked by hyperparasitoids, such as Lysiba nana. The results presented in this thesis show that hyperparasitoids also use HIPVs for host searching. Interestingly, they are especially attracted by plant odours induced by parasitized caterpillars. Moreover, hyperparasitoids can also use caterpillar body odours to find their hosts at close distance. These findings indicate that infochemicals are the major cues that mediate host searching behaviour of hyperparastioids. Similar to other herbivore-associated organisms, parasitoid larvae feeding inside a herbivore host can induce both behavioral and physiological changes in the host. To further investigate how parasitoid larvae indirectly affect plant responses to herbivory and plant volatile-mediated multitrophic interactions, the role of caterpillar labial salivary glands in plant-hyperparasitoid interactions were investigated. The secretions of labial saliva were eliminated by using an ablation technique. Remarkably, the results show that when the labial salivary glands of the caterpillars were completely removed, plants induced by either unparasitized or Cotesia glomerata-parasitized caterpillars were equally attractive to the hyperparasitoid. Moreover, plants became less attractive to the hyperparasitoid when damaged by ablated caterpillars compared to plants damaged by mock-treated caterpillars and the hyperparasitoids were not able to distinguish between volatiles emitted by herbivore-damaged plants and undamaged control plants when caterpillar salivary glands had been removed. These results suggest that parasitism alters the composition of labial saliva of parasitized caterpillar, which thereby alters the plant phenotype and subsequently plant-hyperparasitoid interactions. The outcomes of this thesis contribute to our understanding of the role of infochemicals in foraging decisions of hyperparasitoids.
Rhizobacterial modification of plant defenses against insect herbivores: from molecular mechanisms to tritrophic interactions
Pangesti, N.P.D. - \ 2015
Wageningen University. Promotor(en): Marcel Dicke; Joop van Loon. - Wageningen : Wageningen University - ISBN 9789462572836 - 224
planten - rizosfeerbacteriën - insecten - multitrofe interacties - verdedigingsmechanismen - pseudomonas fluorescens - mamestra brassicae - pieris brassicae - plant-microbe interacties - insect-plant relaties - plant-herbivoor relaties - plants - rhizosphere bacteria - insects - multitrophic interactions - defence mechanisms - plant-microbe interactions - insect plant relations - plant-herbivore interactions
Plants as primary producers in terrestrial ecosystems are under constant threat from a multitude of attackers, which include insect herbivores. In addition to interactions with detrimental organisms, plants host a diversity of beneficial organisms, which include microbes in the rhizosphere. Furthermore, the interactions between plants and several groups of root-associated microbes such as mycorrhizae, plant growth promoting rhizobacteria (PGPR) and plant growth promoting fungi (PGPF) can affect plant interactions with foliar insect herbivores. The beneficial root-associated microbes are able to modify plant physiology by promoting plant growth and induced systemic resistance (ISR), in which the balance between both effects will determine the final impact on the insect herbivores. Using Arabidopsis thaliana Col-0, this thesis explores the molecular mechanisms on how plants integrate responses when simultaneously interacting with the rhizobacterium Pseudomonas fluorescens and the generalist and the specialist leaf-chewing insects Mamestra brassicae and Pieris brassicae respectively.
A literature review on the state-of-the-art in the field of microbe-plant-insect interactions (Chapter 2) explores how root-associated microbes and insect folivores can influence each other via a shared host plant. For more than a decade, both ecological and mechanistic studies mostly focused on exploring these belowground and aboveground interactions using single microbe and single herbivore species. The importance of increasing the complexity of the study system in order to understand the interactions in more natural situations is being emphasized. Furthermore, this review discusses the role of plant hormones in regulating plant growth and defense against folivores, while simultaneously being involved in associations with root-associated microbes.
Experimental evidence has shown patterns on the effects of mycorrhizal colonization on plant interactions with insect herbivores, and raises the question whether plant colonization by different groups of root-associated microbes has similar effects on particular categories of insect herbivores. In Chapter 3, plant-mediated effects of a non-pathogenic rhizobacterium on the performance of leaf-chewing insects, and the underlying mechanisms modulating the interactions, have been examined. Colonization of A. thaliana Col-0 roots by the bacterium P. fluorescens strain WCS417r resulted in decreased larval weight of the generalist leaf-chewing M. brassicae, and had no effect on larval weight of the specialist leaf-chewing P. brassicae. The crucial role of jasmonic acid (JA) in regulating rhizobacteria-mediated induced systemic resistance (ISR) against M. brassicae is confirmed by including plant mutants in the study. Interestingly, I also observed that rhizobacteria can induce systemic susceptibility to M. brassicae caterpillars. Comparison of M. brassicae performance and gene transcription in A. thaliana plants, grown in potting soil or a mixture of potting soil and sand in a 1:1 ratio, shows that in a mixture of potting soil and sand, rhizobacterial treatment had a consistently negative effect on M. brassicae, whereas the effect is more variable in potting soil. Rhizobacterial treatment primed plants grown in potting soil and sand for stronger expression of JA- and ethylene-regulated genes PDF1.2 and HEL, supporting stronger resistance to M. brassicae. Taken together, the results show that soil composition can be one of the factors modulating the outcome of microbe-plant-insect interactions.
Chapter 4 further addresses the mechanisms underlying rhizobacteria-mediated ISR against the generalist leaf-chewing M. brassicae by integrating plant gene transcription, chemistry and performance of M. brassicae in wild type A. thaliana Col-0 plants and mutants defective in the JA-pathway, i.e. dde2-2 and myc2, in the ET pathway, i.e. ein2-1, and in the JA-/ET-pathway, i.e. ora59. Results of this study show that rhizobacterial colonization alone or in combination with herbivore infestation induced the expression of the defense-associated genes ORA59 and PDF1.2 at higher levels than activation by herbivore feeding alone, and the expression of both genes is suppressed in the knock-out mutant ora59. Interestingly, the colonization of plant roots by rhizobacteria alters the levels of plant defense compounds, i.e. camalexin and glucosinolates (GLS), by enhancing the synthesis of constitutive and induced levels of camalexin and aliphatic GLS while suppressing the induced levels of indole GLS. The changes are associated with modulation of the JA-/ET-signaling pathways as shown by investigating mutants. Furthermore, the herbivore performance results show that functional JA- and ET-signaling pathways are required for rhizobacteria-mediated ISR against leaf-chewing insects as observed in the knock-out mutants dde2-2 and ein2-1. The results indicate that colonization of plant roots by rhizobacteria modulates plant-insect interactions by prioritizing the ORA59-branch over the MYC2-branch, although the transcription factor ORA59 is not the only one responsible for the observed effects of rhizobacteria-mediated ISR against leaf-chewing insects.
Taking a step further in increasing the complexity of the study system, Chapter 5 investigates how co-cultivation of P. fluorescens strains WCS417r and SS101 affects direct plant defense to the caterpillar M. brassicae. Inoculation of either P. fluorescens WCS417r or SS101 singly at root tips or simultaneously at two different positions along the roots resulted in a similar level of rhizobacterial colonization by each strain, whereas co-cultivation of both strains at either the root tips or at two different positions along the roots resulted in a higher colonization level of strain WCS417r compared to colonization by SS101. The results suggest that the site of inoculation influences the direct interactions between the two strains in the rhizosphere, as also confirmed by in vitro antagonism assays in the absence of plants. Both upon single inoculation and co-cultivation of both strains at the same or different sites along the roots, the two rhizobacterial strains induced the same strength of ISR against the caterpillar M. brassicae and the same degree of plant growth promotion. In the roots, colonization by the two strains as single or mixed culture resulted in a similar gene expression pattern of up-regulation of MYC2, down-regulation of WRKY70 and no effect on NPR1 expression, genes representing JA-signaling, SA-signaling and the node of crosstalk between the two pathways, respectively. We hypothesize that both rhizobacterial strains use negative crosstalk between JA- and SA-pathways as mechanism to suppress plant immunity and establish colonization. This study shows that competitive interactions between rhizobacterial strains known to induce plant defense in systemic tissue via different signaling pathways, may interfere with synergistic effects on ISR and plant growth promotion.
While the effect of root-associated microbes on direct plant defense against insect herbivores has been studied previously, the effect of these microbes on indirect plant defense to herbivores is much less known. Chapter 6 explores how colonization by the rhizobacterium P. fluorescens strain WCS417r affects indirect plant defense against the generalist herbivore M. brassicae by combining behavioral, chemical and gene transcriptional approaches. The results show that rhizobacterial colonization of A. thaliana roots results in an increased attraction of the parasitoid Microplitis mediator to caterpillar-infested plants. Volatile analysis revealed that rhizobacterial colonization suppressed emission of the terpene (E)-α-bergamotene, and the aromatics methyl salicylate and lilial in response to caterpillar feeding. Rhizobacterial colonization decreased the caterpillar-induced transcription of the terpene synthase genes TPS03 and TPS04. Rhizobacteria enhanced both growth and indirect defense of plants under caterpillar attack. This study shows that rhizobacteria have a high potential to enhance the biocontrol of leaf-chewing herbivores based on enhanced attraction of parasitoids.
Taken together, the research presented in this thesis has shown how single or combined applications of rhizobacteria affect interactions of plants with leaf-chewing insects in terms of direct and indirect resistance. Furthermore, results presented in this thesis have revealed some of the molecular mechanisms underlying plant-mediated interactions between rhizobacteria and leaf-chewing insects that can be used in developing practical approaches by applying beneficial root-associated microbes for improving plant resistance.
Tales on insect-flowering plant interactions : the ecological significance of plant responses to herbivores and pollinators
Lucas Gomes Marques Barbosa, D. - \ 2015
Wageningen University. Promotor(en): Marcel Dicke, co-promotor(en): Joop van Loon. - Wageningen : Wageningen University - ISBN 9789462572119 - 207
bloeiende planten - insecten - insect-plant relaties - plant-herbivoor relaties - herbivoren - bestuivers (dieren) - trofische graden - parasitoïden - herbivoor-geinduceerde plantengeuren - flowering plants - insects - insect plant relations - plant-herbivore interactions - herbivores - pollinators - trophic levels - parasitoids - herbivore induced plant volatiles - cum laude
cum laude graduation
Insects on individual plants : plant quality, plant diversity and aboveground-belowground effects
Kostenko, O. - \ 2014
Wageningen University. Promotor(en): Wim van der Putten, co-promotor(en): T.M. Bezemer. - Wageningen : Wageningen University - ISBN 9789461738639 - 231
insecten - planten - insect-plant relaties - boven- en ondergrondse interacties - soortendiversiteit - parasitoïden - plant-herbivoor relaties - senecio jacobaea - fauna - insects - plants - insect plant relations - aboveground belowground interactions - species diversity - parasitoids - plant-herbivore interactions
Planten en insecten vormen de basis van veel ecosystemen en ze zijn verantwoordelijk voor belangrijke ecologische functies. Gedurende de laatste drie decennia zijn ecologen en entomologen zich er steeds meer bewust van geworden dat het aantal insecten en de soortsamenstelling van die insecten op één plantensoort sterk kan variëren tussen individuen van die plantensoort. Het is echter nog steeds niet duidelijk welke factoren verantwoordelijk zijn voor deze variatie en op welke manier die variatie tot stand komt. Met meer kennis hierover kunnen we beter voorspellen hoe insectengemeenschappen er op een bepaalde plant uitzien en hoe ze zullen reageren op veranderingen in het milieu. Eerder onderzoek heeft aangetoond dat zowel de kwaliteit van de waardplant (zoals de hoeveelheid voedingsstoffen en plantverdedigingsstoffen) als haar omgeving insecten kunnen beïnvloeden. In dit promotieonderzoek heb ik met een combinatie van kas- en veldexperimenten onderzocht hoe intraspecifieke variatie in de waardplantkwaliteit en de omringende planten de insectengemeenschap op een individuele plant bepalen. Ik heb dit onderzoek gedaan met Jakobskruiskruid (Jacobaea vulgaris Gaertner ssp. vulgaris) en de bovengrondse en ondergrondse multitrofe gemeenschap waar deze plant mee geaffilieerd is.
Kuiters, A.T. ; Casaer, J. - \ 2010
In: Bosecologie en Bosbeheer / Muys, B., den Ouden, J., Mohren, G.M.J., Verheyen, K., Leuven : ACCO - ISBN 9789033477829 - p. 417 - 424.
bossen - plantengemeenschappen - plant-herbivoor relaties - forests - plant communities - plant-herbivore interactions
Naast grote herbivoren kunnen ook kleinere zoogdieren een effect hebben op bosvegetatie, zij het over het algemeen op een beperktere schaal. In deze bijdrage met name aandacht voor het aanvreten van bosvegetatie door hoefdieren. De effecten op vegetatie en bodem, en populatiedynamiek bij hoefdieren. Tot slot de maatschappelijke aspecten van een duurzaam wildbeheer
Plant-mediated multitrophic interactions between aboveground and belowground insects
Soler Gamborena, R. - \ 2009
Entomologische Berichten 69 (2009)6. - ISSN 0013-8827 - p. 202 - 210.
planten - insecten - bodeminsecten - herbivoren - trofische graden - brassicaceae - insect-plant relaties - multitrofe interacties - plant-herbivoor relaties - plants - insects - soil insects - herbivores - trophic levels - insect plant relations - multitrophic interactions - plant-herbivore interactions
Het is bekend dat planten als verticale communicatiekanalen kunnen fungeren tussen onder-en bovengrondse plantetende insecten. Worteleters veroorzaken veranderingen in biomassa en de chemische samenstelling van de bovengrondse delen van een plant. Deze veranderingen kunnen de overleving, de groei en de ontwikkeling van bladeters beïnvloeden. In het promotieproject werd onderzocht of en hoe de wisselwerking tussen ruimtelijk gescheiden insecten beperkt is tot planteneters, dan wel uitgebreid kan worden naar hogere trofische niveaus zoals bijvoorbeeld parasitaire wespen, de natuurlijke vijanden van de plantenetende insecten. Tijdens de 20e Nederlandse Entomologendag (19 december 2008) is de eerste NEV dissertatieprijs uitgereikt aan dit proefschrift
On the risk of extinction of a wild plant species through spillover of a biological control agent: analysis of an ecosystem compartment model
Chalak-Haghighi, M. ; Hemerik, L. ; Werf, W. van der; Ierland, E.C. van - \ 2008
Wageningen : Mansholt Graduate School (Working paper / Mansholt Graduate School of Social Sciences : Discussion paper ) - 37
onkruidbestrijding - biologische bestrijding - wilde planten - uitsterven - verspreiding - ecosystemen - natuurlijke vijanden - gewas onkruid concurrentie - plant-herbivoor relaties - weed control - biological control - wild plants - extinction - dispersal - ecosystems - natural enemies - crop weed competition - plant-herbivore interactions
Invasive plant species can be controlled by introducing one or more of their natural enemies (herbivores) from their native range; however such introduction entails the risk that the introduced natural enemy will attack indigenous plant species in the area of introduction. The effect of spillover of a natural enemy from a managed ecosystem compartment (agriculture) in the area of introduction to a natural compartment (non-managed) in which an indigenous plant species is attacked by the introduced natural enemy, whereas another indigenous plant species, which competes with the first, is not attacked, has been studied. The combination of competition and herbivory may result in extinction of the attacked wild plant species. Using a modelling approach, the authors have determined model parameters that characterize the risk of extinction. The findings point to the importance of spillover and the relative attack rates (specificity) of introduced natural enemies with respect to target and non-target plant species
Linking variation in plant defence to biodiversity at higher trophic levels: a multidisciplinary approach
Poelman, E.H. - \ 2008
Wageningen University. Promotor(en): Marcel Dicke; Louise Vet, co-promotor(en): Joop van Loon; N.M. van Dam. - [S.l.] : s.n. - ISBN 9789085049623 - 163
brassica oleracea - cotesia - parasitoïden - verdedigingsmechanismen - hyperparasieten - trofische graden - gastheer parasiet relaties - pieris brassicae - insectenplagen - plant-herbivoor relaties - herbivoor-geinduceerde plantengeuren - parasitoids - defence mechanisms - hyperparasites - trophic levels - host parasite relationships - insect pests - plant-herbivore interactions - herbivore induced plant volatiles - cum laude
cum laude graduation (with distinction)
Gewasbescherming van opkomst tot oogst in de gesloten productie
Janssen, A. ; Maanen, R. van; Messelink, G.J. ; Sabelis, M.W. - \ 2008
Gewasbescherming 39 (2008)Suppl.. - ISSN 0166-6495 - p. 17 - 17.
biologische bestrijding - kassen - voedselwebben - voedselketens - interacties - analytische methoden - risicoschatting - glastuinbouw - agro-ecosystemen - plant-herbivoor relaties - insect-plant relaties - biological control - greenhouses - food webs - food chains - interactions - analytical methods - risk assessment - greenhouse horticulture - agroecosystems - plant-herbivore interactions - insect plant relations
Genetica, chemie en ecologie van een kwalitatief glucosinolaatpolymorfisme in barbarakruid (Barbarea vulgaris)
Leur, H. van - \ 2008
Gewasbescherming 39 (2008)3. - ISSN 0166-6495 - p. 108 - 110.
gewasbescherming - barbarea vulgaris - glucosinolaten - chemotypen - genetica - nematoda - plaagresistentie - experimenteel veldonderzoek - plant-herbivoor relaties - plant protection - glucosinolates - chemotypes - genetics - pest resistance - field experimentation - plant-herbivore interactions
Op 17 maart 2008 promoveerde Hanneke van Leur aan Wageningen Universiteit op het proefschrift getiteld 'Genetics, chemistry and ecology of a qualitative glucosinolate polymorphism in Barbarea vulgaris). Uit haar onderzoek kan op basis van de gehouden kas- en veldproeven geconcludeerd worden dat de structuur van de glucosinaten significante verschillen veroorzaakt in resistentie tegen verschillende herbivoren. Het is echter niet zo dat het ene chemotype in alle gevallen meer resistent is dan het andere chemotype.
Tritrophic interactions in wild and cultivated brassicaceous plant species
Gols, R. - \ 2008
Wageningen University. Promotor(en): Marcel Dicke. - S.l. : S.n. - ISBN 9789085049210 - 219
brassica - parasitoïden - insectenplagen - natuurlijke vijanden - multitrofe interacties - plant-herbivoor relaties - parasitoids - insect pests - natural enemies - multitrophic interactions - plant-herbivore interactions
Plants have evolved a range of defence traits that prevent or reduce attack by insect herbivores. Direct defence traits hamper or reduce the performance and behaviour of the herbivores, whereas indirect defence promote the efficiency of natural enemies to attack the herbivores. Here, I focused on chemical plant defences, both direct and indirect, in brassicaceous plant species. Glucosinolates (GS), which are secondary plant compounds characteristic for the Brassicaceae, may not only affect growth and survival of herbivores, they may also reduce the performance of the herbivore’s natural enemies such as parasitoids. Brassicaceous plant species, like most plant species, emit volatile organic compounds in response to herbivore feeding damage. These herbivore-induced plant volatiles (HIPV’s) can be used by parasitoids of these herbivores to locate a host-infested plant. The production of HIPV’s is a form of chemical indirect defence and is also studied here. The Brassicaceae family contains important crop plants such as cabbages and oilseeds. However, through artificial selection, the chemistry in crop plants may have been modified compared with their wild conspecifics in which defence traits are the result of natural selection. I compared the performance of herbivore and parasitoid species that differed in
their food plant, respectively host specialisation, on several cultivated and wild conspecific plant populations. The specialist herbivore-parasitoid systems were not affected by the relatively high GS concentrations in leaf tissues of three mustard species (both wild and cultivated populations). However, the performance of even a specialist herbivore and its parasitoid differed on wild populations of B. oleracea compared to their performance on a B. oleracea cultivar. Development of a generalist herbivore and its parasitoid were even more strongly affected by differences in quality among the wild B. oleracea populations. Differences in plant quality affected not only pupal/adult mass and development time, as was found for the specialists, but also strongly reduced survival. Whether artificial selection has resulted in chemical changes with concomitant effects on the performance of their associated insects depends on the crop trait that has been selected for. Direct and indirect plant
defences are usually investigated in separate studies. However, a conflict between direct and indirect defences may arise when a parasitoid female is attracted to a plant on which the development of her offspring is compromised. I studied the performance of two different parasitoid species on three different mustard species and also recorded their attraction to volatiles from host-infested plants. No conflicts between direct and indirect defences were revealed. Parasitoid females were attracted to plants on which their offspring was not negatively affected by the food plant quality of the host. Many studies comparing parasitoid attraction to HIPV’s are conducted in Y-tube olfactometer or windtunnel experiments. However, under natural conditions parasitoids have to search for hosts in heterogeneous environments with different plant species that can be attacked by several herbivores. I observed parasitoid foraging behaviour in a slightly more complex set-up. Female D. semiclausum took more time to find a single host-infested B. oleracea plant in a set-up consisting of B. oleracea plants interspersed with a second brassicaceous plant species, S. alba, than in a monospecific set-up with only B. oleracea plants. Thus, B. oleracea plants
may provide the herbivore with a chemical refuge against parasitism in the presence of highly attractive S. alba plants. Comparison of the foraging behaviour and population dynamics of hosts and their parasitoids in managed agricultural and unmanaged natural ecosystems may provide new insights into the mechanisms underlying tritrophic interactions and may help to reveal the importance of bottom-up and top-down control of arthropod herbivores.
Infochemical use in Brassica-insect interactions : a phenotypic manipulation approach to induced plant defences
Bruinsma, M. - \ 2008
Wageningen University. Promotor(en): Marcel Dicke, co-promotor(en): Joop van Loon. - [S.l.] : S.n. - ISBN 9789085049265 - 169
brassicaceae - verdediging - herbivoren - jasmonzuur - pieris rapae - pieris brassicae - fenotypen - plant-herbivoor relaties - defence - herbivores - jasmonic acid - phenotypes - plant-herbivore interactions
Plants have developed a range of strategies to defend themselves against herbivore attack. Defences can be constitutive, i.e. always present independent of attack, or induced, i.e. only elicited when the plant is under attack. In this thesis, I focused on induced chemical defence responses of plants and the response of associated insects to these phenotypic changes in plants. Herbivore attack is known to induce chemical defences in Brassicaceous plants. Using several elicitors and inhibitors of different steps of the signalling pathways underlying herbivore-induced plant responses, I studied how induced infochemicals affect interactions with associated insects.
Jasmonic acid (JA) is a key plant hormone in the octadecanoid signalling pathway known to be involved in herbivore-induced plant defences. Application of JA can induce plant responses that are similar, although not identical, to herbivore feeding. Two specialist herbivores of Brassicaceous plants, the butterflies Pieris rapae and P. brassicae, preferred to oviposit on non-induced plants over JA-induced plants. Development of P. rapae caterpillars was shown to be reduced, suggesting that oviposition avoidance on JA-induced plants is adaptive. The levels of glucosinolates, secondary metabolites of Brassicaceous plants that are used by Pieris butterflies as oviposition stimulants, could not explain the observed oviposition preference of the butterflies.
JA-induced changes in the plants also affected members of the third trophic level. Volatile emission of JA-induced plants attracted parasitoid wasps to the plants. Parasitoid attraction to JA-induced plants was shown to depend on dose and induction time. However, using JA to induce phenotypic changes had effects different from those induced by herbivores, both chemically and ecologically. Volatile emission of JA-induced and herbivore-induced plants differed; whereas JA-induced plants emitted larger amounts of volatiles, the parasitoids preferred herbivore-induced plants over JA-treated ones.
Early events in plant defence responses, involved in attacker recognition, are damage-induced modulations of ion channel activities resulting in ion imbalances. The fungal elicitor alamethicin, an ion channel-forming peptide mixture, was used to mimic early steps in defence responses. Alamethicin treatment increased attractiveness of plants to parasitoid wasps. Although volatile emission of alamethicin-treated plants was much lower, they were equally attractive as JA-treated plants. This indicates that quality rather than quantity of induced plant volatile blends is important to parasitoids.
Besides chemical elicitation of herbivore-induced responses, which is a widely applied approach, plant defence responses can also be chemically inhibited. This provides the opportunity to inhibit the rate of specific enzymatic steps in a signal-transduction pathway. Furthermore, visual cues associated with feeding damage can be present (and similar) in control- and inhibitor-treated plants. Phenidone is a compound that inhibits lipoxygenase, an enzyme catalyzing an early step in the octadecanoid pathway. Parasitoid attraction was reduced when the plants were treated with phenidone before infestation.
Also herbivore oviposition preference was shown to be affected by inhibition of this signalling pathway. Herbivores can differ in their oviposition preferences. I studied two specialist herbivores with different oviposition preferences: Pieris brassicae avoids oviposition on herbivore-induced plants, whereas Plutella xylostella prefers to oviposit on Pieris-infested plants. I showed that these preferences have a chemical basis and are dependent on octadecanoid signalling, since treatment with the lipoxygenase inhibitor phenidone eliminated herbivore-induced oviposition avoidance or preference.
Thus far, most of the studies on induced plant defences have been done with vegetative plants. However, since reproduction and defence are both processes that require energy and nutrients, this could result in a trade-off. Herbivore feeding on leaves, flowers or roots is known to affect pollinator visitation, but the mechanisms mediating this change have not been addressed. Effects of induction with JA on nectar secretion and pollinator visitation to flowers were investigated. JA-induced plants secreted less nectar, but the sugar concentrations did not change. Also visitation of honeybees and syrphid flies did not change upon JA induction.
These results show the complexity of induced plant defence responses and the variety of behavioural responses of insects on different trophic levels. Combining the phenotypic manipulation approach to induced plant defences, as used in this thesis, with molecular genetic techniques and building on recent developments in plant biochemistry provides a promising way forward towards enhanced understanding of the intricate interactions between plants and insects.
Multitrofe interacties tussen onder- en bovengrondse insecten via de gezamenlijke waardplant
Soler Gamborena, R. - \ 2008
Gewasbescherming 39 (2008)2. - ISSN 0166-6495 - p. 64 - 66.
planten - insecten - bodeminsecten - herbivoren - trofische graden - waardplanten - insect-plant relaties - multitrofe interacties - plant-herbivoor relaties - plants - insects - soil insects - herbivores - trophic levels - host plants - insect plant relations - multitrophic interactions - plant-herbivore interactions
De resultaten van dit proefschrift laten zien dat het voor de bestrijding van bovengrondse plaaginsecten van groot belang is te weten welke ondergrondse insecten aanwezig zijn en wat er rond de wortel van de plant gebeurt, en vice versa. Zulke bovengrondse-ondergrondse interacties tussen insecten via veranderingen in de in de waardplant kunnen namelijk de efficiëntie van bestrijdingsprogramma's significant beïnvloeden
Resource ecology : spatial and temporal dynamics of foraging
Prins, H.H.T. ; Langevelde, F. van - \ 2008
Dordrecht : Springer (Wageningen UR Frontis series vol. 23) - ISBN 9781402068485 - 304
natuurlijke hulpbronnen - hulpbronnenbeheer - ecologie - herbivoren - begrazing - foerageren - voeropname - dieetstudies - bevolkingsspreiding - kuddes (herds) - vee - migratie - voedingsgedrag - ruimtelijke verdeling - grote grazers - plant-herbivoor relaties - natural resources - resource management - ecology - herbivores - grazing - foraging - feed intake - diet studies - population distribution - herds - livestock - migration - feeding behaviour - spatial distribution - large herbivores - plant-herbivore interactions
This multi-author book deals with 'resource ecology', which is the ecology of trophic interactions between consumers and their resources. Resource ecology is perhaps the most central part of ecology. In its linkage between foraging theory and spatial ecology, it shows how old and fundamental questions can be tackled afresh. It addresses crucial aspects of the interactions between consumers and resources. Foraging is the central process in resource ecology because it leads to growth, survival and reproduction of the animal. Resource ecology forms the basis for comprehending the functioning of multi-species assemblages, and is thus key to grasp the organisation of biodiversity. For the purposes of stimulating future research, each chapter ends with two or three testable hypotheses. Each chapter is followed by a comment. This makes the book ideal for teaching and course work, because it highlights the fact that ecology is a living and active research field.
Hoe kunnen we plaagonderdrukkende mengteelten ontwerpen?
Bukovinszky, T. ; Lenteren, J.C. van - \ 2007
Entomologische Berichten 67 (2007)6. - ISSN 0013-8827 - p. 231 - 234.
geïntegreerde plagenbestrijding - natuurlijke vijanden - voedselwebben - teeltsystemen - monocultuur - populatie-ecologie - landbouwkundige entomologie - plant-herbivoor relaties - functionele biodiversiteit - agrobiodiversiteit - integrated pest management - natural enemies - food webs - cropping systems - monoculture - population ecology - agricultural entomology - plant-herbivore interactions - functional biodiversity - agro-biodiversity
Plaagpopulaties zijn vaak kleiner in mengteelten dan in monocultures. Met mengteelten kan daarom worden geprobeerd plaagproblemen in agro-ecosystemen te verkleinen. Een grotere vegetatiediversiteit kan plaagorganismen onderdrukken doordat waardplanten minder goed zichtbaar of van geringere kwaliteit zijn en doordat natuurlijke vijanden meer voedsel vinden. Helaas is de respons op mengteelten van zowel plaaginsecten als van hun natuurlijke vijanden. Vaak moeilijk te voorspellen en er is nog onvoldoende kennis om in concrete gevallen de plaagpopulatieverschillen tussen mengteelten die plagen onderdrukken vereist daarom meer studie. In dit artikel laten we zien dat recent verworven kennis van het gedrag en de ecologie van plant-plaag-natuurlijke vijand interacties een nieuw beeld oplevert van het verschil tussen mono- en mengcultures
Costs and benefits of iridoid glycosides in multitrophic systems
Talsma, J.H. - \ 2007
Wageningen University. Promotor(en): Louise Vet, co-promotor(en): A. Biere; J.A. Harvey. - [S.l.] : S.n. - ISBN 9789085048435 - 151
planten - verdedigingsmechanismen - herbivoren - insectenplagen - hyperparasieten - iridoïdeglycosiden - plant-herbivoor relaties - multitrofe interacties - plants - defence mechanisms - herbivores - insect pests - hyperparasites - iridoid glycosides - plant-herbivore interactions - multitrophic interactions
Plant-mediated multitrophic interactions between aboveground and belowground insects
Soler Gamborena, R. - \ 2007
Wageningen University. Promotor(en): Louise Vet; Wim van der Putten, co-promotor(en): J.A. Harvey; T.M. Bezemer. - [S.l.] : S.n. - ISBN 9789085047384 - 172
planten - insecten - bodeminsecten - herbivoren - trofische graden - insect-plant relaties - multitrofe interacties - plant-herbivoor relaties - plants - insects - soil insects - herbivores - trophic levels - insect plant relations - multitrophic interactions - plant-herbivore interactions
Herbivory can induce changes in plant growth, physiology, morphology, and phenology. Such herbivore-induced changes by insects are commonly observed in many plant species. Changes in the host plant can alter interaction linkages between plants, herbivores and higher trophic levels such as carnivores of the herbivores. These interaction linkages shape community organization and biodiversity in plant-based terrestrial communities. Considering that plants have both aboveground and belowground parts, systemic herbivore-induced changes within the plant could potentially link spatially separated herbivores associated with plants in the soil and in the aboveground (sub) system. Relatively recently, an increasing number of studies have shown that root herbivores, among other soil dwelling organisms, can indeed interact with foliar herbivores. Root herbivores change the quality and biomass of aboveground plant parts, which in turn influences the growth, development and survival of foliar herbivores. Similarly, foliar-feeding insects have been shown to influence root-feeding insects. This thesis explores whether, and mechanistically how, these feed-backs between root and foliar herbivores are transmitted through the soil and the aboveground food chains influencing the performance and behaviour of higher trophic levels. In Chapter 1, I introduce plant-insect interactions in a multitrophic context, briefly describing how the plant mediates these intricate interactions, and I describe the general aim and the outline of the thesis. In Chapter 2 I study the effects of root herbivores, at different densities, on the biomass and quality of the plant shoot, and on the performance of a foliar herbivore, its primary parasitoid and its secondary parasitoid (hyperparasitoid) sharing the host plant. In Chapter 3 I study the reverse effect; the effects of foliar herbivores on a root herbivore and its parasitoid mediated by the host plant. The results of these Chapters show that the spatially separated herbivores negatively affect each other's performances by increasing the levels of secondary plant compounds within the host plant. These negative effects are not restricted to the herbivore level, but are transmitted to the parasitoids and the hyperparasitoids, reducing in particular the growth and size of the off-spring of the aboveground parasitoid. Based on the results of Chapter 2, where I observed a marked suboptimal performance of the off-spring of the aboveground parasitoid when sharing the host plant with root herbivores, I investigate in Chapter 4 whether female parasitoids of foliar herbivores can exploit root herbivore-related cues to select the most suitable hosts for their offspring. In this Chapter I show that female parasitoids avoid to parasitise hosts feeding on plants shared with root herbivores, when hosts feeding on root-undamaged plants are available. The mechanism points to changes in the volatile blend of the plant triggered by the root-feeding insects. After observing this strong interaction between root herbivores and aboveground parasitoids mediated by the host-infested plant, in Chapter 5, I investigate whether root herbivores influence the behaviour of female parasitoids also indirectly via changes in the surrounding habitat. I provide evidence that root-feeding insects can influence the behaviour and foraging efficiency of parasitoids of foliar herbivores, even when the foliar (parasitoid-host) and the root herbivores do not feed on the same plant, but on neighbouring conspecific plants within the same habitat. The above described results are based on experiments carried out under controlled conditions in the laboratory or semi-field experiments in large, enclosed cages. To test some of the lab-based results under more natural conditions, I conducted a field experiment in which several cohorts of mustard plants with and without root herbivores were placed in the field and were monitored aboveground for the presence of foliar herbivores over the course of a summer season. To investigate whether the spatial distribution of root-damaged plants influences the plant preference of the foliar-feeders, I arranged the plants in the field in plots either in clusters of root-undamaged and root-damaged plants, or root-undamaged and root-damaged plants homogeneously mixed. Specialised foliar herbivores were observed feeding and ovipositing preferentially on root- ____________________________________________________________ Summary uninfested plants over plants shared with root herbivores. Interestingly, one of the species only discriminates against root-damaged plants when the plants were grouped in clusters. This thesis shows that the strong feedbacks between root and shoot associated organisms can significantly influence the performance and behaviour of organisms of higher trophic levels. Therefore, interactive effects of aboveground and belowground organisms cannot be limited to organisms directly associated with the shared host plant because they occur throughout a complex multitrophic chain of organisms. Furthermore, this thesis underlines the importance of considering not only the mere presence or absence of the soil dwelling organisms, but show that the density and distribution of root herbivores can determine the outcome of the interactions with their aboveground counterparts. These interactions are mediated by the shared host plant, via induced changes in the secondary plant compounds within the plant and in the plant volatile blend. Consumers in one compartment can change the quality of the plant in the opposite compartment, as well as induce changes in the emission of the plant volatiles used by carnivores that forage for hosts. Moreover, I provide evidence that spatially separated insects can interact not only via changes in the shared host plant, but also more indirectly via changes in the quality of the surrounding habitat. This suggest that aboveground-belowground multitrophic interactions can occur and interact in much more complex ways than what has been reported so far. In the last experimental Chapter I provide evidence that behavioural decisions in naturally occurring populations of foliar-feeding insects can also be influenced by root-feeding insects, under field conditions where several complex interactions take place simultaneously. In the final Chapter, I summarise the results presented in this thesis and provide a general conclusion of the work. I identify a number of important areas and topics for future research to further gain insight into aboveground-belowground multitrophic interactions.