Staff Publications

Staff Publications

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

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

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

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    The Nesidiocoris tenuis genome manuscript supporting data
    Pannebakker, Bart ; Ferguson, Kimberley - \ 2019
    Wageningen University & Research
    genome - biocontrol - biological control - insect - mirid - Nesidiocoris tenuis - genomics - genome assembly
    In presenting the first mirid genome, Nesidiocoris tenuis, several supporting information is made available. Following the main supplemetary material document (link), the contents are in this database: S1.2. Flow cytometry data for N. tenuis S1.3. Decontamination and potential LGT indentification S1.4. Gene list (UniProtKB list) and DAVID Reports S1.5. Full protein set S1.7. Poolseq results in full
    The Trichogramma brassicae genome, supporting data
    Pannebakker, Bart ; Ferguson, Kimberley - \ 2019
    Wageningen University & Research
    genome - biocontrol - biological control - insect - parasitoid - Trichogramma - Trichogramma brassicae - genome assembly
    In presenting the Trichogramma brassicae genome, supporting information is made available. Following the main supplemetary material document, the contents in this database entry are as follows: S1.2. Contaminated Wolbachia scaffolds from assembly v3.0 (Backbone_1176.fa and Backbone_1392.fa) S1.3. DAVID input gene list S1.5. Full Trichogramma brassicae protein set from annotation.
    The Bracon brevicornis genome, supporting data
    Pannebakker, Bart ; Ferguson, Kimberley - \ 2019
    Wageningen University & Research
    genome - biocontrol - biological control - insect - parasitoid - Trichogramma - Trichogramma brassicae - genome assembly
    In presenting the Bracon brevicornis genome, supporting information is made available. The material available in this database entry are as follows: 1. Contamination scaffolds from decontamination process (note, identified as being neither the carrier DNA of tomato, nor belonging to the group Arthropoda in a BlobTools analysis. For more details, refer to source manuscript. 2. Two sets of pseudohaplotype FASTA files, generated from decontaminated B. brevicornis reads and output from Supernova assembler.
    Data from: Modulation of plant-mediated interactions between herbivores of different feeding guilds: effects of parasitism and belowground interactions
    Vaello, Teresa ; Sarde, Sandeep ; Marcos-García, Mª Ángeles ; Boer, J.G. de; Pineda, Ana - \ 2018
    plant soil feedback - herbivory - plant defense - insect - parasitism - gene expression
    Herbivory affects subsequent herbivores, mainly regulated by the phytohormones jasmonic (JA) and salicylic acid (SA). Additionally, organisms such as soil microbes belowground or parasitoids that develop inside their herbivorous hosts aboveground, can change plant responses to herbivory. However, it is not yet well known how organisms of trophic levels other than herbivores, below- and above-ground, alter the interactions between insect species sharing a host plant. Here, we investigated whether the parasitoid Aphidius colemani and different soil microbial communities (created through plant-soil feedbacks) affect the JA and SA signalling pathways in response to the aphid Myzus persicae and the thrips Frankliniella occidentalis, as well as subsequent thrips performance. Our results show that the expression of the JA-responsive gene CaPINII in sweet pepper was more suppressed by aphids than by parasitised aphids. However, parasitism did not affect the expression of CaPAL1, a biosynthetic gene of SA. Furthermore, aphid feeding enhanced thrips performance compared with uninfested plants, but this was not observed when aphids were parasitised. Soils where different plant species were previously grown, did not affect plant responses or the interaction between herbivores. Our study shows that members of the third trophic level can modify herbivore interactions by altering plant physiology.
    Supplementary Material for: Nasonia Parasitic Wasps Escape from Haller's Rule by Diphasic, Partially Isometric Brain-Body Size Scaling and Selective Neuropil Adaptations
    Groothuis, J. ; Smid, H.M. - \ 2017
    Haller's rule - brain - insect - Nasonia vitripennis - parasitic wasp - confocal laser scanning microscopy - plasticity - neuropil - mushroom body
    Data from: Escaping blood-fed malaria mosquitoes minimize tactile detection without compromising on take-off speed
    Muijres, F.T. ; Chang, S.W. ; Veen, W.G. van; Spitzen, J. ; Biemans, Bart ; Koehl, M.A.R. ; Dudley, R. - \ 2017
    malaria mosquito - aerodynamics - biomechanics - flight behaviour - insect - take-off maneuvers - wingbeat kinematics - muscle morphology - Anopheles coluzzii
    To escape after taking a blood meal, a mosquito must exert forces sufficiently high to take off when carrying a load roughly equal to its body weight, while simultaneously avoiding detection by minimizing tactile signals exerted on the host's skin. We studied this trade-off between escape speed and stealth in malaria mosquitoes, Anopheles coluzzii, using 3D motion analysis of high-speed stereoscopic videos of mosquito take-offs and aerodynamic modelling. We found that during the push-off phase, mosquitoes enhanced take-off speed by using aerodynamic forces generated by the beating wings in addition to leg-based push-off forces, whereby wing forces contributed 61% to the total push-off force. Exchanging leg-derived push-off forces for wing-derived aerodynamic forces allows the animal to reduce peak force production on the host's skin. By slowly extending their long legs throughout the push-off, mosquitoes spread push-off forces over a longer time window than insects with short legs, thereby further reducing peak leg forces. Using this specialized take-off behavior, mosquitoes are capable of reaching take-off speeds comparable to those of similarly-sized fruit flies, but with weight-normalized peak leg forces that were only 27% of those of the fruit flies. By limiting peak leg forces, mosquitoes possibly reduce the chance of being detected by the host. The resulting combination of high take-off speed and low tactile signals on the host might help increase the mosquito's success to escape from blood-hosts, which consequently also increases the chance that they transmit vector-borne diseases, such as malaria, to future hosts.
    Baculovirus-induced tree-top disease: how extended is the role of egt as a gene for the extended phenotype?
    Ros, V.I.D. ; Houte, S. van; Hemerik, L. ; Oers, M.M. van - \ 2015
    Molecular Ecology 24 (2015)1. - ISSN 0962-1083 - p. 249 - 258.
    spodoptera-exigua larvae - udp-glucosyl transferase - escherichia-coli - lepidopteran host - trichoplusia-ni - deletion - nucleopolyhedrovirus - behavior - insect - infection
    Many parasites alter host behaviour to enhance their chance of transmission. Recently, the ecdysteroid UDP-glucosyl transferase (egt) gene from the baculovirus Lymantria dispar multiple nucleopolyhedrovirus (LdMNPV) was identified to induce tree-top disease in L. dispar larvae. Infected gypsy moth larvae died at elevated positions (hence the term tree-top disease), which is thought to promote dissemination of the virus to lower foliage. It is, however, unknown whether egt has a conserved role among baculoviruses in inducing tree-top disease. Here, we studied tree-top disease induced by the baculovirus Autographa californica multiple nucleopolyhedrovirus (AcMNPV) in two different host insects, Trichoplusia ni and Spodoptera exigua, and we investigated the role of the viral egt gene therein. AcMNPV induced tree-top disease in both T. ni and S. exigua larvae, although in S. exigua a moulting-dependent effect was seen. Those S. exigua larvae undergoing a larval moult during the infection process died at elevated positions, while larvae that did not moult after infection died at low positions. For both T. ni and S. exigua, infection with a mutant AcMNPV lacking egt did not change the position where the larvae died. We conclude that egt has no highly conserved role in inducing tree-top disease in lepidopteran larvae. The conclusion that egt is a ‘gene for an extended phenotype’ is therefore not generally applicable for all baculovirus–host interactions. We hypothesize that in some baculovirus–host systems (including LdMNPV in L. dispar), an effect of egt on tree-top disease can be observed through indirect effects of egt on moulting-related climbing behaviour.
    Directional movement in response to altered flow in six lowland stream Trichoptera
    Verdonschot, P.F.M. ; Besse, A.A. ; Dekkers, T.B.M. ; Verdonschot, R.C.M. - \ 2014
    Hydrobiologia 740 (2014)1. - ISSN 0018-8158 - p. 219 - 230.
    lotic macroinvertebrates - benthic invertebrates - field experiments - upstream movements - river systems - drift - colonization - habitat - refugia - insect
    Understanding the trait adaptations associated with mobility in Trichoptera larvae under different flow conditions would enhance the understanding of survival mechanisms under flow stress induced by spates. In stream mesocosms, we mimicked a lowland stream spate by suddenly increasing current velocity above an organic habitat patch from 10 to 30 or 50 cm/s. Subsequently, we investigated whether short-term, small-scale movements in six Trichoptera species were not random but directional and whether the type of movement was related to the magnitude of flow increase. Main types of response distinguished were as follows: (1) resistance, in which the species remained in the habitat patch, (2) upstream or downstream crawling, and (3) being dislodged from the streambed and drift downstream (vulnerability). The type of response observed was related to the species’ ecological preferences and morphological traits. The experiment showed that movement in Trichoptera larvae was directional and flow-dependent. Drift was the main mechanism observed with an increase in current velocity, but upstream crawling and aggregation in the habitat patch were observed as well. The type and magnitude of the response were highly species specific. It appeared that each combination of morphological and behavioral adaptations developed individually for each species under niche-specific conditions.
    Development and thermal requirements of the Nearctic predator Geocoris punctipes (Hemiptera: Geocoridae) reared at constant and alternating temperatures and fed on Anagasta kuehniella (Lepidoptera: Pyralidae) eggs
    Calixto, A.M. ; Bueno, V.H.P. ; Montes, F.C. ; Lenteren, J.C. van - \ 2014
    European Journal of Entomology 111 (2014)4. - ISSN 1210-5759 - p. 521 - 528.
    biological-control agents - insidiosus say hemiptera - orius-insidiosus - tuta absoluta - life-history - prey - anthocoridae - heteroptera - lygaeidae - insect
    Knowledge of the optimal temperatures for development and survival of biological control agents is essential for efficient mass-rearing and introduction of natural enemies in augmentative biological control programs. We studied the effect of constant and alternating temperatures on development and survival of immature stages and the sex ratio at emergence of adults of the Nearctic generalist predator Geocoris punctipes (Say). We also determined its thermal requirements. They were reared in climatic chambers at alternating (21/11°C, 24/18°C, 27/21°C and 30/26°C ± 1°C) and constant temperatures (16.8°C, 21.5°C, 24.5°C and 28.3°C ± 1°C), RH 70 ± 10% and a 14 h photophase. Survival and development of G. punctipes were the same when reared at constant and alternating temperatures. Five instars were recorded in all temperature regimes. The duration of the egg stage and each instar, as well as that of total larval development were longer, and larval survival lower when reared at 16.8°C, 21/11°C, 21.5°C and 24/18°C than at 24.5°C, 27/21°C, 28.3°C and 30/26°C. The optimal temperature range for development and survival of G. punctipes is 24.5°C to 30°C, its lower development threshold temperature is 13.5°C and its thermal constant 295.9 DD. Sex ratios were not significantly different from 1 : 1 male : female ratio in all temperature regimes. There is an excellent match between the temperature regimes at which the prey Tuta absoluta (Meyrick) and predator G. punctipes are active, which indicates that this predator will function well in crops where this pest is present.
    Body odors of parasitized caterpillars give away the presence of parasitoid larvae to their primary hyperparasitoid enemies
    Zhu, F. ; Weldegergis, B.T. ; Lhie, B. ; Harvey, J.A. ; Dicke, M. ; Poelman, E.H. - \ 2014
    Journal of Chemical Ecology 40 (2014)9. - ISSN 0098-0331 - p. 986 - 995.
    cotesia-rubecula hymenoptera - induced plant volatiles - foraging behavior - pieris-brassicae - host location - herbivore - insect - ecology - fitness - wasp
    Foraging success of parasitoids depends on the utilization of reliable information on the presence of their often, inconspicuous hosts. These parasitic wasps use herbivore-induced plant volatiles (HIPVs) that provide reliable cues on host presence. However, host searching of hyperparasitoids, a group of parasitoids that parasitize the larvae and pupae of other parasitoids, is more constrained. Their hosts do not feed on plants, and often are even concealed inside the body of the herbivore host. Hyperparasitoids recently have been found to use HIPVs of plants damaged by herbivore hosts in which the parasitoid larvae develop. However, hyperparasitoids that search for these parasitoid larvae may be confronted with healthy and parasitized caterpillars on the same plant, further complicating their host location. In this study, we addressed whether the primary hyperparasitoid Baryscapus galactopus uses caterpillar body odors to discriminate between unparasitized herbivores and herbivores carrying larvae of parasitoid hosts. We show that the hyperparasitoids made faster first contact and spent a longer mounting time with parasitized caterpillars. Moreover, although the three parasitoid hosts conferred different fitness values for the development of B. galactopus, the hyperparasitoids showed similar behavioral responses to caterpillar hosts carrying different primary parasitoid hosts. In addition, a two-chamber olfactometer assay revealed that volatiles emitted by parasitized caterpillars were more attractive to the hyperparasitoids than those emitted by unparasitized caterpillars. Analysis of volatiles revealed that body odors of parasitized caterpillars differ from unparasitized caterpillars, allowing the hyperparasitoids to detect their parasitoid host.
    Reciprocal crosstalk between jasmonate and salicylate defence-signalling pathways modulates plant volatile emission and herbivore host-selection behaviour
    Wei, J. ; Loon, J.J.A. van; Gols, R. ; Menzel, T.R. ; Li, N. ; Kang, L. ; Dicke, M. - \ 2014
    Journal of Experimental Botany 65 (2014)12. - ISSN 0022-0957 - p. 3289 - 3298.
    mediated interactions - specialist herbivore - tetranychus-urticae - induced resistance - parasitic wasps - cotton plants - spider-mites - insect - acid - pathogen
    The jasmonic acid (JA) and salicylic acid (SA) signalling pathways, which mediate induced plant defence responses, can express negative crosstalk. Limited knowledge is available on the effects of this crosstalk on host-plant selection behaviour of herbivores. We report on temporal and dosage effects of such crosstalk on host preference and oviposition-site selection behaviour of the herbivorous spider mite Tetranychus urticae towards Lima bean (Phaseolus lunatus) plants, including underlying mechanisms. Behavioural observations reveal a dynamic temporal response of mites to single or combined applications of JA and SA to the plant, including attraction and repellence, and an antagonistic interaction between SA- and JA-mediated plant responses. Dose-response experiments show that concentrations of 0.001mM and higher of one phytohormone can neutralize the repellent effect of a 1mM application of the other phytohormone on herbivore behaviour. Moreover, antagonism between the two signal-transduction pathways affects phytohormone-induced volatile emission. Our multidisciplinary study reveals the dynamic plant phenotype that is modulated by subtle changes in relative phytohormonal titres and consequences for the dynamic host-plant selection by an herbivore. The longer-term effects on plant–herbivore interactions deserve further investigation.
    Unraveling the Entry Mechanism of Baculoviruses and Its Evolutionary Implications
    Wang, M. ; Wang, J. ; Yin, F. ; Tan, Y. ; Deng, F. ; Chen, X. ; Jehle, J.A. ; Vlak, J.M. ; Hu, Zhihong ; Wang, H. - \ 2014
    Journal of Virology 88 (2014)4. - ISSN 0022-538X - p. 2301 - 2311.
    envelope fusion protein - californica multicapsid nucleopolyhedrovirus - nuclear polyhedrosis-virus - mammalian-cells - f-proteins - gp64 - infectivity - insect - identification - neutralization
    The entry of baculovirus budded virus into host cells is mediated by two distinct types of envelope fusion proteins (EFPs), GP64 and F protein. Phylogenetic analysis suggested that F proteins were ancestral baculovirus EFPs, whereas GP64 was acquired by progenitor group I alphabaculovirus more recently and may have stimulated the formation of the group I lineage. This study was designed to experimentally recapitulate a possible major step in the evolution of baculoviruses. We demonstrated that the infectivity of an F-null group II alphabaculovirus (Helicoverpa armigera nucleopolyhedrovirus [HearNPV]) can be functionally rescued by coinsertion of GP64 along with the nonfusogenic Fdef (furin site mutated HaF) from HearNPV. Interestingly, HearNPV enters cells by endocytosis and, less efficiently, by direct membrane fusion at low pH. However, this recombinant HearNPV coexpressing Fdef and GP64 mimicked group I virus not only in its EFP composition but also in its abilities to enter host cells via low-pH-triggered direct fusion pathway. Neutralization assays indicated that the nonfusogenic F proteins contribute mainly to binding to susceptible cells, while GP64 contributes to fusion. Coinsertion of GP64 with an F-like protein (Ac23) from group I virus led to efficient rescue of an F-null group II virus. In summary, these recombinant viruses and their entry modes are considered to resemble an evolutionary event of the acquisition of GP64 by an ancestral group I virus and subsequent adaptive inactivation of the original F protein. The study described here provides the first experimental evidence to support the hypothesis of the evolution of baculovirus EFPs.
    Jasmonate and ethylene signaling mediate whitefly-induced interference with indirect plant defense in Arabidopsis thaliana
    Zhang, P.J. ; Broekgaarden, C. ; Zheng, S.J. ; Snoeren, T.A.L. ; Loon, J.J.A. van; Gols, R. ; Dicke, M. - \ 2013
    New Phytologist 197 (2013)4. - ISSN 0028-646X - p. 1291 - 1299.
    salicylic-acid - transcriptome changes - feeding guilds - tomato plants - herbivores - volatiles - insect - responses - gene - involvement
    Upon herbivore attack, plants activate an indirect defense, that is, the release of a complex mixture of volatiles that attract natural enemies of the herbivore. When plants are simultaneously exposed to two herbivore species belonging to different feeding guilds, one herbivore may interfere with the indirect plant defense induced by the other herbivore. However, little is understood about the mechanisms underlying such interference. Here, we address the effect of herbivory by the phloem-feeding whitefly Bemisia tabaci on the induced indirect defense of Arabidopsis thaliana plants to Plutella xylostella caterpillars, that is, the attraction of the parasitoid wasp Diadegma semiclausum. Assays with various Arabidopsis mutants reveal that B. tabaci infestation interferes with indirect plant defense induced by P. xylostella, and that intact jasmonic acid and ethylene signaling are required for such interference caused by B. tabaci. Chemical analysis of plant volatiles showed that the composition of the blend emitted in response to the caterpillars was significantly altered by co-infestation with whiteflies. Moreover, whitefly infestation also had a considerable effect on the transcriptomic response of the plant to the caterpillars. Understanding the mechanisms underlying a plant’s responses to multiple attackers will be important for the development of crop protection strategies in a multi-attacker context.
    A multi-criteria risk analysis to evaluate impacts of forest management alternatives on forest health in Europe
    Jactel, H. ; Branco, M. ; Duncker, P. ; Gardiner, B. ; Grodzki, W. ; Langström, B. ; Moreira, F. ; Netherer, S. ; Nicoll, B. ; Orazio, C. ; Piou, D. ; Schelhaas, M.J. ; Tojic, K. - \ 2012
    Ecology and Society 17 (2012)4. - ISSN 1708-3087
    decision-making - stand management - promethee method - climate-change - strong winds - model - damage - drought - insect - populations
    Due to climate change, forests are likely to face new hazards, which may require adaptation of our existing silvicultural practices. However, it is difficult to imagine a forest management approach that can simultaneously minimize all risks of damage. Multicriteria decision analysis (MCDA) has been developed to help decision makers choose between actions that require reaching a compromise among criteria of different weights. We adapted this method and produced a multicriteria risk analysis (MCRA) to compare the risk of damage associated with various forest management systems with a range of management intensity. The objective was to evaluate the effect of four forest management alternatives (FMAs) (i.e., close to nature, extensive management with combined objectives, intensive even-aged plantations, and short-rotation forestry for biomass production) on biotic and abiotic risks of damage in eight regional case studies combining three forest biomes (Boreal, Continental, Atlantic) and five tree species (Eucalyptus globulus, Pinus pinaster, Pinus sylvestris, Picea sitchensis, and Picea abies) relevant to wood production in Europe. Specific forest susceptibility to a series of abiotic (wind, fire, and snow) and biotic (insect pests, pathogenic fungi, and mammal herbivores) hazards were defined by expert panels and subsequently weighted by corresponding likelihood. The PROMETHEE ranking method was applied to rank the FMAs from the most to the least at risk. Overall, risk was lower in short-rotation forests designed to produce wood biomass, because of the reduced stand susceptibility to the most damaging hazards. At the opposite end of the management intensity gradient, close-to-nature systems also had low overall risk, due to lower stand value exposed to damage. Intensive even-aged forestry appeared to be subject to the greatest risk, irrespective of tree species and bioclimatic zone. These results seem to be robust as no significant differences in relative ranking of the four FMAs were detected between the combinations of forest biomes and tree species.
    Resistance factors in pepper inhibit larval development of thrips (Frankliniella occidentalis)
    Maharijaya, A. ; Vosman, B.J. ; Verstappem, F. ; Steenhuis-Broers, M.M. ; Mumm, R. ; Purwito, A. ; Visser, R.G.F. ; Voorrips, R.E. - \ 2012
    Entomologia Experimentalis et Applicata 145 (2012)1. - ISSN 0013-8703 - p. 62 - 71.
    western flower thrips - life-history parameters - colorado potato beetle - host-plant quality - glandular trichomes - wild tomato - thysanoptera - behavior - insect - growth
    The western flower thrips [Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae)] is a major pest in pepper cultivation. Therefore, host plant resistance to thrips is a desirable trait. The objectives of this study were to determine the effect of resistance on the development of thrips and to identify metabolite compounds related to the resistance. Three highly resistant, three medium resistant, and three susceptible pepper accessions were used in this study. Adult and pre-adult survival, developmental time, and oviposition rate were assessed. Gas chromatography-mass spectrometry was used to identify compounds that correlate with the level of resistance to thrips. Our results show that resistance of pepper accessions has a significant effect on oviposition rate and larval mortality. Seven compounds were identified that correlate with resistance to thrips and six compounds were identified that correlate with susceptibility to thrips. Some of these compounds, such as tocopherols, were previously shown to have an effect on insects in general. Also, some specific secondary metabolites (alkanes) seem to be more abundant in susceptible accessions and were induced by thrips infestation
    Temporal dynamics of herbivore-induced responses in Brassica juncea and their effect on generalist and specialist herbivores
    Mathur, V. ; Ganta, S. ; Raaijmakers, C.E. ; Reddy, A.S. ; Vet, L.E.M. ; Dam, N.M. van - \ 2011
    Entomologia Experimentalis et Applicata 139 (2011)3. - ISSN 0013-8703 - p. 215 - 225.
    plant defense syndromes - black mustard - oilseed rape - wild radish - glucosinolate - volatiles - induction - insect - performance - population
    Herbivore feeding may induce an array of responses in plants, and each response may have its own temporal dynamics. Precise timing of these plant responses is vital for them to have optimal effect on the herbivores feeding on the plant. This study measured the temporal dynamics of various systemically induced responses occurring in Brassica juncea (L.) Czern. (Brassicaceae) leaves after insect herbivory in India and The Netherlands. Morphological (trichomes, leaf size) and chemical (glucosinolates, amino acids, sugars) responses were analysed. The effects of systemic responses were assessed using a specialist [Plutella xylostella L. (Lepidoptera: Plutellidae)] and a generalist [Spodoptera litura Fabricius (Lepidoptera: Noctuidae)] herbivore. We tested the hypotheses that morphological responses were slower than chemical responses and that generalist herbivores would be more affected by induced responses than specialists. Glucosinolates and trichomes were found to increase systemically as quickly as 4 and 7 days after herbivore damage, respectively. Amino acids, sugars, and leaf size remained unaffected during this period. The generalist S. litura showed a significant feeding preference for undamaged leaves, whereas the specialist herbivore P. xylostella preferred leaves that were damaged 9 days before. Performance bioassays on generalist S. litura revealed that larvae gained half the weight on leaves from damaged plants as compared to larvae feeding on leaves from undamaged plants. These studies show that although morphological responses are somewhat slower than chemical responses, they also contribute to induced plant resistance in a relatively short time span. We argue that before considering induced responses as resistance factors, their effect should be assessed at various points in time with both generalist and specialist herbivores.
    Beyond climate envelopes: effects of weather on regional population trends in butterflies
    Wallis de Vries, M.F. ; Baxter, W. ; Vliet, A.J.H. van - \ 2011
    Oecologia 167 (2011)2. - ISSN 0029-8549 - p. 559 - 571.
    extreme weather - habitat fragmentation - range expansion - insect - distributions - responses - impacts - models - temperature - performance
    Although the effects of climate change on biodiversity are increasingly evident by the shifts in species ranges across taxonomical groups, the underlying mechanisms affecting individual species are still poorly understood. The power of climate envelopes to predict future ranges has been seriously questioned in recent studies. Amongst others, an improved understanding of the effects of current weather on population trends is required. We analysed the relation between butterfly abundance and the weather experienced during the life cycle for successive years using data collected within the framework of the Dutch Butterfly Monitoring Scheme for 40 species over a 15-year period and corresponding climate data. Both average and extreme temperature and precipitation events were identified, and multiple regression was applied to explain annual changes in population indices. Significant weather effects were obtained for 39 species, with the most frequent effects associated with temperature. However, positive density-dependence suggested climatic independent trends in at least 12 species. Validation of the short-term predictions revealed a good potential for climate-based predictions of population trends in 20 species. Nevertheless, data from the warm and dry year of 2003 indicate that negative effects of climatic extremes are generally underestimated for habitat specialists in drought-susceptible habitats, whereas generalists remain unaffected. Further climatic warming is expected to influence the trends of 13 species, leading to an improvement for nine species, but a continued decline in the majority of species. Expectations from climate envelope models overestimate the positive effects of climate change in northwestern Europe. Our results underline the challenge to include population trends in predicting range shifts in response to climate change
    On the risk of extinction of a wild plant species through spillover of a biological control agent: Analysis of an ecosystem compartment model.
    Chalak, M. ; Hemerik, L. ; Werf, W. van der; Ruijs, A. ; Ierland, E.C. van - \ 2010
    Ecological Modelling 221 (2010)16. - ISSN 0304-3800 - p. 1934 - 1943.
    agricultural landscapes - biocontrol - insect - weed - management - dispersal - habitats - invasion - prey
    Invasive plant species can be controlled by introducing natural enemies (insect herbivores) from their native range. However, such introduction entails the risk that the introduced herbivores attack indigenous plant species in the area of introduction. Here, we study the effect of spillover of a herbivore from a managed ecosystem compartment (agriculture) to a natural compartment (non-managed) and vice versa. In the natural compartment, an indigenous plant species is attacked by the introduced herbivores, whereas another indigenous plant species, which competes with the first, is not attacked. The combination of competition and herbivory may result in extinction of the attacked wild plant species. Using a modelling approach, we determine model parameters that characterize the risk of extinction for a wild plant species. Risk factors include: (1) a high attack rate of the herbivores on the wild non-target species, (2) niche overlap expressed as strong competition between the attacked non-target species and its competitor(s), and (3) factors favouring large spillover from the managed ecosystem compartment to the natural compartment; these include (3a) a high dispersal ability, and (3b) a moderate attack rate of the introduced herbivore on the target species, enabling large resident populations of the insect herbivore in the managed compartment. The analysis thus indicates that a high attack rate on the target species, which is a selection criterion for biocontrol agents with respect to their effectiveness, also mitigates risks resulting from spillover and non-target effects. While total eradication of an invasive plant species is not possible in the one-compartment-one-plant-one-herbivore system, natural enemy spillover from a natural to a managed compartment can make the invasive weed go extinct.
    Effects of ecological compensation meadows on arthropod diversity in adjacent intensively managed grassland
    Albrecht, M. ; Duelli, P. ; Obrist, M.K. ; Müller, C. ; Schüpbach, B. ; Kleijn, D. ; Schmid, B. - \ 2010
    Biological Conservation 143 (2010)3. - ISSN 0006-3207 - p. 642 - 649.
    agri-environment schemes - agricultural intensification - promoting biodiversity - species richness - body-size - insect - communities - landscapes - conservation - edge
    An important goal of ecological compensation areas (ECAs) is to increase biodiversity in adjacent intensively managed farmland and the agricultural landscape at large. We tested whether this goal can be achieved in the case of the agri-environmental restoration scheme implemented for Swiss grassland using five large arthropod taxa (bees, true bugs, orthopterans, ground beetles and spiders) representing different ecological and functional groups. The species richness and abundance of all groups and species, respectively, was measured along 100 m transects from ECA-meadows into the adjacent intensively managed grassland at 24 sites. Species richness of all arthropod taxa except ground beetles, and the abundance of 63% of the 234 arthropod species sampled with at least five individuals were higher in ECA-meadows than in their surroundings, while the total abundance of spiders and ground beetles was higher in intensively managed meadows. The abundance of 8% of these species were only increased in the ECA-meadows themselves (“stenotopic” species) but 40% had increased abundance both in the ECA-meadows and the adjacent grassland, declining exponentially with increasing distance from ECA-meadows (“edge species”). The 90%-decay distances for these edge species differed among taxonomic groups (117 ± 18 m for true bugs, 137 ± 24 m for spiders, 152 ± 34 m for bees, 167 ± 5.7 m for orthopterans, 185 ± 34 m for ground beetles; mean ±1 standard error) and independent of taxonomic group were larger for large-sized or predacious species than for small-sized or phytophagous species. Because the average distance between neighbouring ECA-meadows in Swiss grassland is only 73 ± 4 m, the current agri-environment scheme very likely enhances arthropod diversity and possibly associated ecosystem services in the Swiss agricultural landscape at large.
    Lateral gene transfer between prokaryotes and multicellular eukaryotes: ongoing and significant?
    Ros, V.I.D. ; Hurst, G.D.D. - \ 2009
    BMC Biology 7 (2009). - ISSN 1741-7007
    wolbachia - chromosome - evolution - genomes - insect
    The expansion of genome sequencing projects has produced accumulating evidence for lateral transfer of genes between prokaryotic and eukaryotic genomes. However, it remains controversial whether these genes are of functional importance in their recipient host. Nikoh and Nakabachi, in a recent paper in BMC Biology, take a first step and show that two genes of bacterial origin are highly expressed in the pea aphid Acyrthosiphon pisum. Active gene expression of transferred genes is supported by three other recent studies. Future studies should reveal whether functional proteins are produced and whether and how these are targeted to the appropriate compartment. We argue that the transfer of genes between host and symbiont may occasionally be of great evolutionary importance, particularly in the evolution of the symbiotic interaction itself
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