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.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    To be in time: egg deposition enhances plant-mediated detection of young caterpillars by parasitoids
    Pashalidou, F.G. ; Gols, R. ; Berkhout, B.W. ; Weldegergis, B.T. ; Loon, J.J.A. van; Dicke, M. ; Fatouros, N.E. - \ 2015
    Oecologia 177 (2015)2. - ISSN 0029-8549 - p. 477 - 486.
    different larval instars - pieris-brassicae - specialist herbivore - volatile emissions - cotesia-glomerata - host location - oviposition - responses - maize - generalist
    Animals use information from their environment while foraging for food or prey. When parasitic wasps forage for hosts, they use plant volatiles induced by herbivore activities such as feeding and oviposition. Little information is available on how wasps exploit specific plant volatiles over time, and which compounds indicate changes in host quality. In experiments investigating the role of herbivore-induced plant volatiles in wasp foraging, induction of plant response is usually achieved by placing larvae on clean plants instead of allowing the natural sequence of events: to let eggs deposited by the herbivore develop into larvae. We compared the attraction of the parasitoid Cotesia glomerata to volatiles emitted by black mustard (Brassica nigra) plants induced by eggs and successive larval stages of the Large Cabbage White butterfly (Pieris brassicae) to the attraction of this parasitoid to black mustard plant volatiles induced only by larval feeding in a wind tunnel setup. We show that wasps are attracted to plants infested with eggs just before and shortly after larval hatching. However, wasp preference changed at later time points towards plants induced only by larval feeding. These temporal changes in parasitoid attraction matched with changes in the chemical compositions of the blends of plant volatiles. Previous studies have shown that host quality/suitability decreases with caterpillar age and that P. brassicae oviposition induces plant defences that negatively affect subsequently feeding caterpillars. We investigated parasitoid performance in hosts of different ages. Wasp performance was positively correlated with preference. Moreover, parasitism success decreased with time and host stage. In conclusion, the behaviour of Cotesia glomerata is fine-tuned to exploit volatiles induced by eggs and early host stages that benefit parasitoid fitness.
    Octopamine-like immunoreactive neurons in the brain and subesophageal ganglion of the parasitic wasps Nasonia vitripennis and N. giraulti
    Haverkamp, A. ; Smid, H.M. - \ 2014
    Cell and Tissue Research 358 (2014)2. - ISSN 0302-766X - p. 313 - 329.
    long-term-memory - honey-bee - schistocerca-gregaria - cotesia-glomerata - natural variation - drosophila brain - nervous-system - locust brain - plant odors - fruit-fly
    Octopamine is an important neuromodulator in the insect nervous system, influencing memory formation, sensory perception and motor control. In this study, we compare the distribution of octopamine-like immunoreactive neurons in two parasitic wasp species of the Nasonia genus, N. vitripennis and N. giraulti. These two species were previously described as differing in their learning and memory formation, which raised the question as to whether morphological differences in octopaminergic neurons underpinned these variations. Immunohistochemistry in combination with confocal laser scanning microscopy was used to reveal and compare the somata and major projections of the octopaminergic neurons in these wasps. The brains of both species showed similar staining patterns, with six different neuron clusters being identified in the brain and five different clusters in the subesophageal ganglion. Of those clusters found in the subesophageal ganglion, three contained unpaired neurons, whereas the other three consisted in paired neurons. The overall pattern of octopaminergic neurons in both species was similar, with no differences in the numbers or projections of the ventral unpaired median (VUM) neurons, which are known to be involved in memory formation in insects. In one other cluster in the brain, located in-between the optic lobe and the antennal lobe, we detected more neurons in N. vitripennis compared with N. giraulti. Combining our results with findings made previously in other Hymenopteran species, we discuss possible functions and some of the ultimate factors influencing the evolution of the octopaminergic system in the insect brain.
    Caterpillar-induced plant volatiles remain a reliable signal for foraging wasps during dual attack with a plant pathogen or non-host insect herbivore
    Ponzio, C.A.M. ; Gols, R. ; Weldegergis, B.T. ; Dicke, M. - \ 2014
    Plant, Cell & Environment 37 (2014)8. - ISSN 0140-7791 - p. 1924 - 1935.
    interspecific interactions - pseudomonas-syringae - arabidopsis-thaliana - phytophagous insects - multiple herbivory - cotesia-glomerata - pieris-brassicae - fungal-infection - natural enemies - damaged plants
    Plants respond to herbivory with the emission of plant volatiles, which can be used by the herbivores' natural enemies to locate their hosts or prey. In nature, plants are often simultaneously confronted with insect herbivores and phytopathogens, potentially interfering with the attraction of the herbivores' enemies as a result of modifications of the induced volatile blend. Here, we investigated parasitoid (Cotesia glomerata) attraction to volatiles of plants challenged by different attackers, either alone or in combination with Pieris brassicae caterpillars, hosts of C.¿glomerata. We used a natural system consisting of Brassica nigra plants, eggs and larvae of P.¿brassicae, Brevicoryne brassicae aphids and the bacterial phytopathogen Xanthomonas campestris pv. campestris. In all cases, parasitoids successfully located host-infested plants, and wasp foraging behaviour was unaffected by the simultaneous presence of a non-host attacker or host eggs. Analysis of the volatile emissions show that the volatile blends of caterpillar-infested treatments were different from those without caterpillars. Furthermore, dually attacked plants could not be separated from those with only caterpillars, regardless of non-host identity, supporting the behavioural data. Our results suggest that, in this system, indirect plant defences may be more resistant to interference than is generally assumed, with volatiles induced during dual attack remaining reliable indicators of host presence for parasitoids.
    Variation in herbivore-induced plant volatiles corresponds with spatial heterogeneity in the level of parasitoid competition and parasitoid exposure to hyperparasitism
    Poelman, E.H. ; Harvey, J.A. ; Loon, J.J.A. van; Vet, L.E.M. ; Dicke, M. - \ 2013
    Functional Ecology 27 (2013)5. - ISSN 0269-8463 - p. 1107 - 1116.
    brassica-oleracea - host discrimination - cotesia-glomerata - interspecific competition - rubecula hymenoptera - foraging efficiency - insect parasitoids - larval parasitoids - habitat complexity - natural enemies
    1.Reproductive success for species in which offspring are confined to a distinct resource depends on the ability of parents to locate reproductive sites as well as the quality of these sites in terms of the food source, risk of predation and competition. To locate hosts for their offspring, parasitic wasps, or parasitoids, use plant odour blends induced by herbivore feeding. These herbivore-induced plant volatiles (HIPVs) may also be used by competitors and predators. Therefore, offspring of parasitoids that respond to the most conspicuous odours may find themselves more frequently involved in competition or predation risk. 2.We studied cultivars of Brassica oleracea that are known to differ in volatile production that underlies attractiveness to parasitoids and asked whether variation in this parameter is associated with a heterogeneous distribution of intrinsic competition among parasitoid larvae and predation risk by hyperparasitoids that parasitize parasitoid larvae or pupae. We inoculated field-grown plants with Pieris caterpillars and, thereafter, exposed them to the natural parasitoid community. We measured the frequency of multiple incidences of parasitism in these herbivores. Cocoons of the parasitoids were collected to identify the degree of hyperparasitism associated with different Brassica cultivars. 3.Pieris caterpillars on cultivars that were more attractive to Cotesia parasitoids were more commonly parasitized by several females of the same (superparasitism) or different wasp species (multiparasitism) than caterpillars on less attractive plants. Cocoons of parasitoids on attractive plants also more frequently produced hyperparasitoids. 4.Our results show that there is heterogeneity in intrinsic competition and risk of hyperparasitism for parasitoids on different cabbage cultivars and that this heterogeneity is likely generated by variation in attraction of parasitoids to HIPVs of these cultivars. We conclude that parasitoids may find themselves between a rock and a hard place as cues for host presence may also predict high levels of competition and risk of predation. We speculate that this affects selection on parasitoid responses to plant odours and enhances selection on traits that make wasps better intrinsic or extrinsic competitors as well as selection for adaptive traits – such as crypsis – that protect them against hyperparasitoids.
    Foraging behaviour by parasitoids in multiherbivore communities
    Rijk, M. de; Dicke, M. ; Poelman, E.H. - \ 2013
    Animal Behaviour 85 (2013)6. - ISSN 0003-3472 - p. 1517 - 1528.
    induced plant volatiles - tritrophic interaction webs - host-searching behavior - cabbage plants - mediated interactions - arabidopsis-thaliana - patch exploitation - cotesia-glomerata - natural enemies - herbivore complexes
    Parasitoid foraging decisions are often affected by community characteristics such as community diversity and complexity. As part of a complex habitat, the presence of unsuitable hosts may affect foraging behaviour of parasitoids. First, unsuitable herbivores may affect the localization of patches where hosts are present. Second, encounters with unsuitable herbivores in the food plant patch may affect parasitoid decisions during their searching behaviour in the patch. In this review, we outline the importance of the presence of unsuitable herbivores on the behavioural responses of parasitoids during both these foraging phases. Nonhosts feeding on a neighbouring plant or on the same plant individual the host is feeding from may affect odour-based searching by parasitoids in a way specific for the species combination studied. Feeding by specific host and nonhost-herbivore combinations may induce volatiles that are more, less or equally attractive compared to those from plants infested by the host only. Within the food patch, mixed presence of host and nonhost may reduce the number of hosts parasitized per time unit and reduce parasitoid foraging efficiency. Importantly, we show that a single nonhost species may have contrasting effects in terms of its effects on odour-based searching and patch residence decisions. We conclude that studying host searching behaviour at both phases of foraging is essential for our understanding of parasitoid foraging behaviour in natural and agricultural settings. We further speculate on the ecological context in which unsuitable herbivores affect either of the two phases of parasitoid foraging.
    Breaking Haller's rule: brain-body size isometry in a minute parasitic wasp.
    Woude, E. van der; Smid, H.M. ; Chittka, L. ; Huigens, M.E. - \ 2013
    Brain, behavior and evolution 81 (2013)2. - ISSN 0006-8977 - p. 86 - 92.
    trichogramma-brassicae - cotesia-glomerata - miniaturization - allometry - insects - evolution - parthenogenesis - coleoptera - ptiliidae - rubecula
    Throughout the animal kingdom, Haller's rule holds that smaller individuals have larger brains relative to their body than larger-bodied individuals. Such brain-body size allometry is documented for all animals studied to date, ranging from small ants to the largest mammals. However, through experimental induction of natural variation in body size, and 3-D reconstruction of brain and body volume, we here show an isometric brain-body size relationship in adults of one of the smallest insect species on Earth, the parasitic wasp Trichogramma evanescens. The relative brain volume constitutes on average 8.2% of the total body volume. Brain-body size isometry may be typical for the smallest species with a rich behavioural and cognitive repertoire: a further increase in expensive brain tissue relative to body size would be too costly in terms of energy expenditure. This novel brain scaling strategy suggests a hitherto unknown flexibility in neuronal architecture and brain modularity.
    Hyperparasitoids Use Herbivore-Induced Plant Volatiles to Locate Their Parasitoid Host
    Poelman, E.H. ; Bruinsma, M. ; Zhu, F. ; Weldegergis, B.T. ; Boursault, A.E. ; Jongema, Y. ; Loon, J.J.A. van; Vet, L.E.M. ; Harvey, J.A. ; Dicke, M. - \ 2012
    PloS Biology 10 (2012)11. - ISSN 1545-7885 - 13 p.
    higher trophic levels - cotesia-glomerata - natural enemies - hymenoptera - braconidae - rubecula - quality - performance - arthropods - behavior
    Plants respond to herbivory with the emission of induced plant volatiles. These volatiles may attract parasitic wasps (parasitoids) that attack the herbivores. Although in this sense the emission of volatiles has been hypothesized to be beneficial to the plant, it is still debated whether this is also the case under natural conditions because other organisms such as herbivores also respond to the emitted volatiles. One important group of organisms, the enemies of parasitoids, hyperparasitoids, has not been included in this debate because little is known about their foraging behaviour. Here, we address whether hyperparasitoids use herbivore-induced plant volatiles to locate their host. We show that hyperparasitoids find their victims through herbivore-induced plant volatiles emitted in response to attack by caterpillars that in turn had been parasitized by primary parasitoids. Moreover, only one of two species of parasitoids affected herbivore-induced plant volatiles resulting in the attraction of more hyperparasitoids than volatiles from plants damaged by healthy caterpillars. This resulted in higher levels of hyperparasitism of the parasitoid that indirectly gave away its presence through its effect on plant odours induced by its caterpillar host. Here, we provide evidence for a role of compounds in the oral secretion of parasitized caterpillars that induce these changes in plant volatile emission. Our results demonstrate that the effects of herbivore-induced plant volatiles should be placed in a community-wide perspective that includes species in the fourth trophic level to improve our understanding of the ecological functions of volatile release by plants. Furthermore, these findings suggest that the impact of species in the fourth trophic level should also be considered when developing Integrated Pest Management strategies aimed at optimizing the control of insect pests using parasitoids.
    High-throughput olfactory conditioning and memory retention test show variation in Nasonia parasitic wasps.
    Hoedjes, K.M. ; Steidle, J.L.M. ; Werren, J.H. ; Vet, L.E.M. ; Smid, H.M. - \ 2012
    Genes, Brain and Behavior 11 (2012)7. - ISSN 1601-1848 - p. 879 - 887.
    long-term-memory - cotesia-glomerata - natural variation - learning rate - vitripennis - hymenoptera - drosophila - pteromalidae - dissection - preference
    Most of our knowledge on learning and memory formation results from extensive studies on a small number of animal species. Although features and cellular pathways of learning and memory are highly similar in this diverse group of species, there are also subtle differences. Closely related species of parasitic wasps display substantial variation in memory dynamics and can be instrumental to understanding both the adaptive benefit of and mechanisms underlying this variation. Parasitic wasps of the genus Nasonia offer excellent opportunities for multidisciplinary research on this topic. Genetic and genomic resources available for Nasonia are unrivaled among parasitic wasps, providing tools for genetic dissection of mechanisms that cause differences in learning. This study presents a robust, high-throughput method for olfactory conditioning of Nasonia using a host encounter as reward. A T-maze olfactometer facilitates high-throughput memory retention testing and employs standardized odors of equal detectability, as quantified by electroantennogram recordings. Using this setup, differences in memory retention between Nasonia species were shown. In both Nasonia vitripennis and Nasonia longicornis, memory was observed up to at least 5 days after a single conditioning trial, whereas Nasonia giraulti lost its memory after 2 days. This difference in learning may be an adaptation to species-specific differences in ecological factors, for example, host preference. The high-throughput methods for conditioning and memory retention testing are essential tools to study both ultimate and proximate factors that cause variation in learning and memory formation in Nasonia and other parasitic wasp species.
    Reward Value Determines Memory Consolidation in Parasitic Wasps
    Kruidhof, H.M. ; Pashalidou, F.G. ; Fatouros, N.E. ; Figueroa, I.A. ; Vet, L.E.M. ; Smid, H.M. ; Huigens, M.E. - \ 2012
    PLoS ONE 7 (2012)8. - ISSN 1932-6203
    long-term-memory - trichogramma wasps - cotesia-glomerata - protein-synthesis - natural variation - apis-mellifera - learning rate - c-rubecula - drosophila - quality
    Animals can store learned information in their brains through a series of distinct memory forms. Short-lasting memory forms can be followed by longer-lasting, consolidated memory forms. However, the factors determining variation in memory consolidation encountered in nature have thus far not been fully elucidated. Here, we show that two parasitic wasp species belonging to different families, Cotesia glomerata (Hymenoptera: Braconidae) and Trichogramma evanescens (Hymenoptera; Trichogrammatidae), similarly adjust the memory form they consolidate to a fitness-determining reward: egg-laying into a host-insect that serves as food for their offspring. Protein synthesis-dependent long-term memory (LTM) was consolidated after single-trial conditioning with a high-value host. However, single-trial conditioning with a low-value host induced consolidation of a shorter-lasting memory form. For Cotesia glomerata, we subsequently identified this shorter-lasting memory form as anesthesia-resistant memory (ARM) because it was not sensitive to protein synthesis inhibitors or anesthesia. Associative conditioning using a single reward of different value thus induced a physiologically different mechanism of memory formation in this species. We conclude that the memory form that is consolidated does not only change in response to relatively large differences in conditioning, such as the number and type of conditioning trials, but is also sensitive to more subtle differences, such as reward value. Reward-dependent consolidation of exclusive ARM or LTM provides excellent opportunities for within-species comparison of mechanisms underlying memory consolidation.
    Plant Volatiles Induced by Herbivore Egg Deposition Affect Insects of Different Trophic Levels
    Fatouros, N.E. ; Lucas-Barbosa, D. ; Weldegergis, B.T. ; Pashalidou, F.G. ; Loon, J.J.A. van; Dicke, M. ; Harvey, J.A. ; Gols, R. ; Huigens, M.E. - \ 2012
    PLoS ONE 7 (2012)8. - ISSN 1932-6203
    furcifera horvath homoptera - elm leaf beetle - whitebacked planthopper - cotesia-glomerata - herbaceous plants - pieris-brassicae - host location - rice plants - oviposition - defense
    Plants release volatiles induced by herbivore feeding that may affect the diversity and composition of plant-associated arthropod communities. However, the specificity and role of plant volatiles induced during the early phase of attack, i.e. egg deposition by herbivorous insects, and their consequences on insects of different trophic levels remain poorly explored. In olfactometer and wind tunnel set-ups, we investigated behavioural responses of a specialist cabbage butterfly (Pieris brassicae) and two of its parasitic wasps (Trichogramma brassicae and Cotesia glomerata) to volatiles of a wild crucifer (Brassica nigra) induced by oviposition of the specialist butterfly and an additional generalist moth (Mamestra brassicae). Gravid butterflies were repelled by volatiles from plants induced by cabbage white butterfly eggs, probably as a means of avoiding competition, whereas both parasitic wasp species were attracted. In contrast, volatiles from plants induced by eggs of the generalist moth did neither repel nor attract any of the tested community members. Analysis of the plant’s volatile metabolomic profile by gas chromatography-mass spectrometry and the structure of the plant-egg interface by scanning electron microscopy confirmed that the plant responds differently to egg deposition by the two lepidopteran species. Our findings imply that prior to actual feeding damage, egg deposition can induce specific plant responses that significantly influence various members of higher trophic levels.
    The effect of different dietary sugars and honey on longevity and fecundity in two hyperparasitoid wasps
    Harvey, J.A. ; Cloutier, J. ; Visser, B. ; Ellers, J. ; Wäckers, F.L. ; Gols, R. - \ 2012
    Journal of Insect Physiology 58 (2012)6. - ISSN 0022-1910 - p. 816 - 823.
    lifetime reproductive success - parasitoid aphytis-melinus - hymenopteran parasitoids - cotesia-glomerata - nutritional-value - mannose toxicity - aphid honeydew - floral nectar - strategies - evolution
    In nature adult insects, such as parasitic wasps or ‘parasitoids’ often depend on supplemental nutritional sources, such as sugars and other carbohydrates, to maximize their life-expectancy and reproductive potential. These food resources are commonly obtained from animal secretions or plant exudates, including honeydew, fruit juices and both floral and extra-floral nectar. In addition to exogenous sources of nutrition, adult parasitoids obtain endogenous sources from their hosts through ‘host-feeding’ behavior, whereby blood is imbibed from the host. Resources obtained from the host contain lipids, proteins and sugars that are assumed to enhance longevity and/or fecundity. Here we conducted an experiment exploring the effects of naturally occurring sugars on longevity and fecundity in the solitary hyperparasitoids, Lysibia nana and Gelis agilis. Although both species are closely related, L. nana does not host-feed whereas G. agilis does. In a separate experiment, we compared reproduction and longevity in G. agilis reared on either honey, a honey-sugar ‘mimic’, and glucose. Reproductive success and longevity in both hyperparasitoids varied significantly when fed on different sugars. However, only mannose- and water-fed wasps performed significantly more poorly than wasps fed on four other sugar types. G. agilis females fed honey produced twice as many progeny as those reared on the honey-sugar mimic or on glucose, whereas female longevity was only reduced on the mimic mixture. This result shows not only that host feeding influences reproductive success in G. agilis, but also that non-sugar constituents in honey do. The importance of non-sugar nutrients in honey on parasitoid reproduction is discussed.
    Natural variation in learning rate and memory dynamics in parasitoid wasps: opportunities for converging ecology and neuroscience
    Hoedjes, K.M. ; Kruidhof, H.M. ; Huigens, M.E. ; Dicke, M. ; Vet, L.E.M. ; Smid, H.M. - \ 2011
    Proceedings of the Royal Society. B: Biological Sciences 278 (2011)1707. - ISSN 0962-8452 - p. 889 - 897.
    long-term-memory - cotesia-glomerata - drosophila-melanogaster - leptopilina-heterotoma - microplitis-croceipes - phytophagous insects - foraging success - infochemical use - apis-mellifera - c-rubecula
    Although the neural and genetic pathways underlying learning and memory formation seem strikingly similar among species of distant animal phyla, several more subtle inter- and intraspecific differences become evident from studies on model organisms. The true significance of such variation can only be understood when integrating this with information on the ecological relevance. Here, we argue that parasitoid wasps provide an excellent opportunity for multi-disciplinary studies that integrate ultimate and proximate approaches. These insects display interspecific variation in learning rate and memory dynamics that reflects natural variation in a daunting foraging task that largely determines their fitness: finding the inconspicuous hosts to which they will assign their offspring to develop. We review bioassays used for oviposition learning, the ecological factors that are considered to underlie the observed differences in learning rate and memory dynamics, and the opportunities for convergence of ecology and neuroscience that are offered by using parasitoid wasps as model species. We advocate that variation in learning and memory traits has evolved to suit an insect's lifestyle within its ecological niche.
    Differing Host Exploitation Efficiencies in Two Hyperparasitoids: When is a ‘Match Made in Heaven’?
    Harvey, J.A. ; Wagenaar, R. ; Gols, R. - \ 2011
    Journal of Insect Behavior 24 (2011)4. - ISSN 0892-7553 - p. 282 - 292.
    cotesia-glomerata - reproductive strategies - endoparasitoid wasp - lysibia-nana - clutch size - parasitoids - hymenoptera - allocation - evolution - araneae
    Host exploitation behavior in two hyperparasitoids, Lysibia nana and Gelis agilis, was compared in single cocoon clusters of their primary parasitoid host, Cotesia glomerata. L. nana reproduces sexually, is fully winged, does not host-feed and matures eggs quite rapidly after eclosion, whereas G. agilis possesses opposite traits. Cohorts of individual hyperparasitoid females of differing age and physiological state were given access to single cocoon clusters of C. glomerata that also varied in age. These results reveal that the reproductive biology of L. nana is well matched to exploit cocoon broods in C. glomerata, suggesting strong a co-evolutionary history with this host. By contrast, G. agilis is much less efficient at exploiting host cocoons and is probably a generalist species that attacks other hosts in nature.
    Natural variation in learning and memory dynamics studied by artificial selection on learning rate in parasitic wasps
    Berg, M. van den; Duivenvoorde, L. ; Wang, G. ; Tribuhl, S.V. ; Bukovinszky, T. ; Vet, L.E.M. ; Dicke, M. ; Smid, H.M. - \ 2011
    Animal Behaviour 81 (2011)1. - ISSN 0003-3472 - p. 325 - 333.
    long-term-memory - consolidated memory - drosophila-melanogaster - experimental evolution - cotesia-glomerata - apis-mellifera - c-rubecula - honeybee - infochemicals - hymenoptera
    Although the neural and genetic pathways underlying learning and memory formation seem strikingly similar among species of distant animal phyla, several more subtle inter- and intraspecific differences become evident from studies on model organisms. The true significance of such variation can only be understood when integrating this with information on the ecological relevance. Here, we argue that parasitoid wasps provide an excellent opportunity for multi-disciplinary studies that integrate ultimate and proximate approaches. These insects display interspecific variation in learning rate and memory dynamics that reflects natural variation in a daunting foraging task that largely determines their fitness: finding the inconspicuous hosts to which they will assign their offspring to develop. We review bioassays used for oviposition learning, the ecological factors that are considered to underlie the observed differences in learning rate and memory dynamics, and the opportunities for convergence of ecology and neuroscience that are offered by using parasitoid wasps as model species. We advocate that variation in learning and memory traits has evolved to suit an insect's lifestyle within its ecological niche
    Identification of Biologically Relevant Compounds in Aboveground and Belowground Induced Volatile Blends
    Dam, N.M. van; Qiu, B.L. ; Hordijk, C.A. ; Vet, L.E.M. ; Jansen, J.J. - \ 2010
    Journal of Chemical Ecology 36 (2010)9. - ISSN 0098-0331 - p. 1006 - 1016.
    herbivore-induced volatiles - partial least-squares - jasmonic acid - specialist herbivore - cotesia-glomerata - parasitic wasps - natural enemies - plants - root - performance
    Plants under attack by aboveground herbivores emit complex blends of volatile organic compounds (VOCs). Specific compounds in these blends are used by parasitic wasps to find their hosts. Belowground induction causes shifts in the composition of aboveground induced VOC blends, which affect the preference of parasitic wasps. To identify which of the many volatiles in the complex VOC blends may explain parasitoid preference poses a challenge to ecologists. Here, we present a case study in which we use a novel bioinformatics approach to identify biologically relevant differences between VOC blends of feral cabbage (Brassica oleracea L.). The plants were induced aboveground or belowground with jasmonic acid (JA) and shoot feeding caterpillars (Pieris brassicae or P. rapae). We used Partial Least Squares--Discriminant Analysis (PLSDA) to integrate and visualize the relation between plant-emitted VOCs and the preference of female Cotesia glomerata. Overall, female wasps preferred JA-induced plants over controls, but they strongly preferred aboveground JA-induced plants over belowground JA-induced plants. PLSDA revealed that the emission of several monoterpenes was enhanced similarly in all JA-treated plants, whereas homoterpenes and sesquiterpenes increased exclusively in aboveground JA-induced plants. Wasps may use the ratio between these two classes of terpenes to discriminate between aboveground and belowground induced plants. Additionally, it shows that aboveground applied JA induces different VOC biosynthetic pathways than JA applied to the root. Our bioinformatic approach, thus, successfully identified which VOCs matched the preferences of the wasps in the various choice tests. Additionally, the analysis generated novel hypotheses about the role of JA as a signaling compound in aboveground and belowground induced responses in plants
    CREB expression in the brains of two closely related parasitic wasp species that differ in long-term memory formation
    Berg, M. van den; Verbaarschot, P.G.H. ; Hontelez, S. ; Vet, L.E.M. ; Dicke, M. ; Smid, H.M. - \ 2010
    Insect Molecular Biology 19 (2010)3. - ISSN 0962-1075 - p. 367 - 379.
    element-binding-protein - camp-response element - transcription factor creb - central-nervous-system - snail lymnaea-stagnalis - cyclic-amp - messenger-rna - cotesia-glomerata - drosophila-melanogaster - targeted mutation
    The cAMP/PKA signalling pathway and transcription factor cAMP response element-binding protein (CREB) play key roles in long-term memory (LTM) formation. We used two closely related parasitic wasp species, Cotesia glomerata and Cotesia rubecula, which were previously shown to be different in LTM formation, and sequenced at least nine different CREB transcripts in both wasp species. The splicing patterns, functional domains and amino acid sequences were similar to those found in the CREB genes of other organisms. The predicted amino acid sequences of the CREB isoforms were identical in both wasp species. Using real-time quantitative PCR we found that two low abundant CREB transcripts are differentially expressed in the two wasps, whereas the expression levels of high abundant transcripts are similar.
    Behaviour of male and female parasitoids in the field: influence of patch size, host density, and habitat complexity
    Bezemer, T.M. ; Harvey, J.A. ; Kamp, A.F.D. ; Wagenaar, R. ; Gols, R. ; Kostenko, O. ; Fortuna, T.F.M. ; Engelkes, T. ; Vet, L.E.M. ; Putten, W.H. van der; Soler, R. - \ 2010
    Ecological Entomology 35 (2010)3. - ISSN 0307-6946 - p. 341 - 351.
    aphidius-nigripes hymenoptera - c-rubecula hymenoptera - cotesia-glomerata - foraging behavior - natural enemies - volatile infochemicals - apanteles-glomeratus - weather conditions - insect herbivores - spp. hymenoptera
    1. Two field experiments were carried out to examine the role of patch size, host density, and complexity of the surrounding habitat, on the foraging behaviour of the parasitoid wasp Cotesia glomerata in the field. 2. First, released parasitoids were recaptured on patches of one or four Brassica nigra plants, each containing 10 hosts that were placed in a mown grassland area. Recaptures of females were higher than males, and males and females aggregated at patches with four plants. 3. In experiment 2, plants containing 0, 5 or 10 hosts were placed in unmown grassland plots that differed in plant species composition, on bare soil, and on mown grassland. Very low numbers of parasitoids were recaptured in the vegetated plots, while high numbers of parasitoids were recaptured on plants placed on bare soil or in mown grassland. Recaptures were higher on plants on bare soil than on mown grassland, and highest on plants containing 10 hosts. The host density effect was significantly more apparent in mown grassland than on bare soil. 4. Cotesia glomerata responds in an aggregative way to host density in the field. However, host location success is determined mostly by habitat characteristics, and stronger host or host-plant cues are required when habitat complexity increases.
    Comparing induction at an early and late step in signal transduction mediating indirect defence in Brassica oleracea
    Bruinsma, M. ; Pang, B. ; Mumm, R. ; Loon, J.J.A. van; Dicke, M. - \ 2009
    Journal of Experimental Botany 60 (2009)9. - ISSN 0022-0957 - p. 2589 - 2599.
    plant-volatile biosynthesis - jasmonic acid - arabidopsis-thaliana - salicylic-acid - cross-talk - pieris caterpillars - cotesia-glomerata - insect herbivory - tendril coiling - gene-expression
    The induction of plant defences involves a sequence of steps along a signal transduction pathway, varying in time course. In this study, the effects of induction of an early and a later step in plant defence signal transduction on plant volatile emission and parasitoid attraction are compared. Ion channel-forming peptides represent a class of inducers that induce an early step in signal transduction. Alamethicin (ALA) is an ion channel-forming peptide mixture from the fungus Trichoderma viride that can induce volatile emission and increase endogenous levels of jasmonic acid (JA) and salicylic acid in plants. ALA was used to induce an early step in the defence response in Brussels sprouts plants, Brassica oleracea var. gemmifera, and to study the effect on volatile emission and on the behavioural response of parasitoids to volatile emission. The parasitoid Cotesia glomerata was attracted to ALA-treated plants in a dose-dependent manner. JA, produced through the octadecanoid pathway, activates a later step in induced plant defence signal transduction, and JA also induces volatiles that are attractive to parasitoids. Treatment with ALA and JA resulted in distinct volatile blends, and both blends differed from the volatile blends emitted by control plants. Even though JA treatment of Brussels sprouts plants resulted in higher levels of volatile emission, ALA-treated plants were as attractive to C. glomerata as JA-treated plants. This demonstrates that on a molar basis, ALA is a 20 times more potent inducer of indirect plant defence than JA, although this hormone has more commonly been used as a chemical inducer of plant defence
    Life-history traits in closely related secondary parasitoids sharing the same primary parasitoid host: evolutionary opportunities and constraints
    Harvey, J.A. ; Wagenaar, R. ; Bezemer, T.M. - \ 2009
    Entomologia Experimentalis et Applicata 132 (2009)2. - ISSN 0013-8703 - p. 155 - 164.
    egg-production - body-size - hymenopteran parasitoids - reproductive strategies - endoparasitoid wasp - cotesia-glomerata - asobara-tabida - lysibia-nana - trade-off - allocation
    Thus far, few studies have compared life-history traits amongst secondary parasitoids attacking and developing in cocoons of their primary parasitoid hosts. This study examines development and reproduction in Lysibia nana Gravenhorst and Acrolyta nens Hartig (both Hymenoptera: Ichneumonidae), two related and morphologically similar secondary parasitoids that attack pupae of the gregarious endoparasitoid, Cotesia glomerata L. (Hymenoptera: Braconidae). On black mustard, Brassica nigra L. (Brassicaceae) plants in a field plot, adults of L. nana and A. nens frequently emerged from the same cocoon broods of C. glomerata. Based on similarities in their phylogeny and morphology, it was hypothesized that both species would exhibit considerable overlap in other life-history traits. In both L. nana and A. nens, adult wasp size increased with host cocoon mass at parasitism, although L. nana wasps were slightly larger than A. nens wasps, and completed their development earlier. Adult females of both species emerged with no eggs but matured eggs at similar rates over the following days. When provided with 20 host cocoons daily, fecundity in female L. nana was slightly more skewed towards early life than in A. nens, although lifetime fecundity did not differ between the two species. Longevity was significantly reduced in females of both species that were provided with hosts. Both parasitoids were found to exhibit strong similarities in life-history and development traits and in their ecological niche, thereby supporting our general hypothesis. Competition between L. nana and A. nens is presumably diffused because their preferred host (C. glomerata) is relatively abundant in open habitats.
    Jasmonic acid-induced volatiles of Brassica oleracea attract parasitoids: effects of time and dose, and comparison with induction by herbivores
    Bruinsma, M. ; Posthumus, M.A. ; Mumm, R. ; Mueller, M.J. ; Loon, J.J.A. van; Dicke, M. - \ 2009
    Journal of Experimental Botany 60 (2009)9. - ISSN 0022-0957 - p. 2575 - 2587.
    diadegma-semiclausum hellen - c-rubecula hymenoptera - plant defense - arabidopsis-thaliana - cotesia-glomerata - natural enemies - chewing insects - trophic levels - corn plants - specialist
    Caterpillar feeding induces direct and indirect defences in brassicaceous plants. This study focused on the role of the octadecanoid pathway in induced indirect defence in Brassica oleracea. The effect of induction by exogenous application of jasmonic acid (JA) on the responses of Brussels sprouts plants and on host-location behaviour of associated parasitoid wasps was studied. Feeding by the biting¿chewing herbivores Pieris rapae and Plutella xylostella resulted in significantly increased endogenous levels of JA, a central component in the octadecanoid signalling pathway that mediates induced plant defence. The levels of the intermediate 12-oxophyto-dienoic acid (OPDA) were significantly induced only after P. rapae feeding. Three species of parasitoid wasps, Cotesia glomerata, C. rubecula, and Diadegma semiclausum, differing in host range and host specificity, were tested for their behavioural responses to volatiles from herbivore-induced, JA-induced, and non-induced plants. All three species were attracted to volatiles from JA-induced plants compared with control plants; however, they preferred volatiles from herbivore-induced plants over volatiles from JA-induced plants. Attraction of C. glomerata depended on both timing and dose of JA application. JA-induced plants produced larger quantities of volatiles than herbivore-induced and control plants, indicating that not only quantity, but also quality of the volatile blend is important in the host-location behaviour of the wasps
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