Data from: Managing trap-nesting bees as crop pollinators: spatiotemporal effects of floral resources and antagonists
Dainese, Matteo ; Riedinger, Verena ; Holzschuh, Andrea ; Kleijn, D. ; Scheper, J.A. ; Steffan-Dewenter, Ingolf - \ 2017
Wageningen University & Research
ecosystem services - landscape context - mass-flowering crops - natural enemies - nesting resources - off-field practices - oilseed rape - resource limitation - solitary bees - top-down or bottom-up control
1. The decline of managed honeybees and the rapid expansion of mass-flowering crops increase the risk of pollination limitation in crops and raise questions about novel management approaches for wild pollinators in agroecosystems. Adding artificial nesting sites, such as trap nests, can promote cavity-nesting bees in agroecosystems, but effectiveness could be limited by the availability of floral resources in the surrounding landscape and by natural antagonists. 2. In two European regions, we exposed artificial trap nests in paired field boundaries adjacent to oilseed rape (OSR) fields or non-flowering crops for two years within 32 landscapes covering two independent gradients of OSR cover and semi-natural habitat (SNH) cover in the landscape. We analysed the effects of local and landscape-wide floral resource availability, land-use intensity, landscape complexity and natural antagonists on community composition and population dynamics of trap-nesting bees. 3. Number of brood cells showed a strong, three-fold increase in response to the additional nesting sites. Species richness and abundance of cavity-nesting bees that were active during OSR flowering increased significantly with increasing amount of early-season landscape-wide floral resource availability, such as the cultivation of OSR. Later foraging species benefited instead from the availability of late-season alternative flower resources or SNH cover once the mass-flowering had ceased. Density-dependent parasitism increased following mass-flowering, while no density-dependent effect was found during mass-flowering. 4. Structural equation modelling revealed that the influence of floral resource availability on community growth rate was mediated by community size. Community size showed a strong negative effect on community growth rate. Despite positive density-dependent parasitism, antagonists had only weak regulating effects on community growth rate. 5. Synthesis and applications. Trap-nesting bee populations grow markedly with the increasing availability of food resources in the landscape and effectiveness of trap nests is only marginally limited by natural antagonists. Thus, trap nests could be a simple pollinator-supporting strategy to accompany the current expansion of mass-flowering crops, and to ensure pollination services for insect-pollinated crops. Trap nests benefit not only early season active generalist bees during oilseed rape flowering but also species with later phenology if accompanied by other pollinator-supporting practices.
Data from: Can above-ground ecosystem services compensate for reduced fertilizer input and soil organic matter in annual crops?
Gils, S.H. van; Putten, W.H. van der; Kleijn, D. - \ 2016
agro-ecosystem - insect pests - oilseed rape - pollination - rapeseed - Evergestis extimalis - Brassica napus
Above-ground and below-ground environmental conditions influence crop yield by pollination, pest pressure, and resource supply. However, little is known about how interactions between these factors contribute to yield. Here, we used oilseed rape Brassica napus to test their effects on crop yield. We exposed potted plants to all combinations of high and low levels of soil organic matter (SOM) and fertilizer supply, and placed all treatments at a variety of field sites representing a gradient in pollinator visitation rate and pest exposure. We determined the relative contribution of pollinators and pests, SOM and fertilizer supply to yield. We also tested whether SOM can moderate effects of fertilizer on yield and whether soil conditions influence the relationship between above-ground conditions and yield. Increases in pollinator visitation rate and decreases in pest pressure enhanced yield more than increase of fertilizer supply. Although higher SOM content resulted in plants with more biomass and flowers, under our experimental conditions SOM neither enhanced yield, nor influenced effects of fertilizer, pollinators or pests on yield. The relationships between yield, pollinator visitation rate and pest pressure did not depend on the level of fertilization suggesting that the effects of fertilizer application and above-ground (dis)services on yield were additive. In contrast, pollinator visitation rate was more strongly related to yield at low pest pressure than at high pest pressure indicating trade-offs between above-ground services and disservices. Synthesis and applications. Our results show that it is possible to increase oilseed rape yield by enhancing pollination, irrespective of supplying mineral fertilizer. Moreover, the fact that below-ground conditions did not alter the effect of above-ground conditions, suggests that farmers may obtain even higher yields by maximizing both above-ground ecosystem services and external inputs. Further studies are needed to understand at which point the positive relationships between pollinator visitation and yield, as well as between fertilizer and yield will level off. Considering above-ground and below-ground services and inputs in agro-ecosystems in conjunction is crucial in order to optimize external inputs for crop yield from an economic and ecological perspective.
Robust cropping systems to tackle pests under climate change. A review
Lamichhane, J.R. ; Barzman, M. ; Booij, C.J.H. ; Boonekamp, P.M. ; Desneux, N. ; Huber, L. ; Kudsk, P. ; Langrell, S.R.H. ; Ratnadass, A. ; Ricci, P. ; Sarah, J.L. ; Messéan, A. - \ 2015
Agronomy for Sustainable Development 35 (2015)2. - ISSN 1774-0746 - p. 443 - 459.
phoma stem canker - plant-disease - change impacts - oilseed rape - pseudomonas-aeruginosa - puccinia-striiformis - range expansion - food security - tuta-absoluta - elevated co2
Agriculture in the twenty-first century faces the challenge of meeting food demands while satisfying sustainability goals. The challenge is further complicated by climate change which affects the distribution of crop pests (intended as insects, plants, and pathogenic agents injurious to crops) and the severity of their outbreaks. Increasing concerns over health and the environment as well as new legislation on pesticide use, particularly in the European Union, urge us to find sustainable alternatives to pesticide-based pest management. Here, we review the effect of climate change on crop protection and propose strategies to reduce the impact of future invasive as well as rapidly evolving resident populations. The major points are the following: (1) the main consequence of climate change and globalization is a heightened level of unpredictability of spatial and temporal interactions between weather, cropping systems, and pests; (2) the unpredictable adaptation of pests to a changing environment primarily creates uncertainty and projected changes do not automatically translate into doom and gloom scenarios; (3) faced with uncertainty, policy, research, and extension should prepare for worst-case scenarios following a “no regrets” approach that promotes resilience vis-à-vis pests which, at the biophysical level, entails uncovering what currently makes cropping systems resilient, while at the organizational level, the capacity to adapt needs to be recognized and strengthened; (4) more collective approaches involving extension and other stakeholders will help meet the challenge of developing more robust cropping systems; (5) farmers can take advantage of Web 2.0 and other new technologies to make the exchange of updated information quicker and easier; (6) cooperation between historically compartmentalized experts in plant health and crop protection could help develop anticipation strategies; and (7) the current decline in skilled crop protection specialists in Europe should be reversed, and shortcomings in local human and financial resources can be overcome by pooling resources across borders
Effector-triggered defence against apoplastic fungal pathogens
Stotz, H.U. ; Mitrousia, G.K. ; Wit, P.J.G.M. de; Fitt, B.D.L. - \ 2014
Trends in Plant Science 19 (2014)8. - ISSN 1360-1385 - p. 491 - 500.
programmed cell-death - plant immune-system - cf-2-dependent disease resistance - leptosphaeria-maculans - cladosporium-fulvum - brassica-napus - mycosphaerella-graminicola - avirulence gene - rhynchosporium-secalis - oilseed rape
R gene-mediated host resistance against apoplastic fungal pathogens is not adequately explained by the terms pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) or effector-triggered immunity (ETI). Therefore, it is proposed that this type of resistance is termed 'effector-triggered defence' (ETD). Unlike PTI and ETI, ETD is mediated by R genes encoding cell surface-localised receptor-like proteins (RLPs) that engage the receptor-like kinase SOBIR1. In contrast to this extracellular recognition, ETI is initiated by intracellular detection of pathogen effectors. ETI is usually associated with fast, hypersensitive host cell death, whereas ETD often triggers host cell death only after an elapsed period of endophytic pathogen growth. In this opinion, we focus on ETD responses against foliar fungal pathogens of crops.
Identification of seed-related QTL in Brassica rapa
Bagheri, H. ; Pino del Carpio, D. ; Hanhart, C.J. ; Bonnema, A.B. ; Keurentjes, J.J.B. ; Aarts, M.G.M. - \ 2013
Spanish Journal of Agricultural Research 11 (2013)4. - ISSN 1695-971X - p. 1085 - 1093.
quantitative trait loci - genetic-linkage map - campestris l - turnip rape - flowering time - oilseed rape - oil content - color - inheritance - napus
To reveal the genetic variation, and loci involved, for a range of seed-related traits, a new F2 mapping population was developed by crossing Brassica rapa ssp. parachinensis L58 (CaiXin) with B. rapa ssp. trilocularis R-o-18 (spring oil seed), both rapid flowering and self-compatible. A linkage map was constructed using 97 AFLPs and 21 SSRs, covering a map distance of 757 cM with an average resolution of 6.4 cM, and 13 quantitative trait loci (QTL) were detected for nine traits. A strong seed colour QTL (LOD 26) co-localized with QTL for seed size (LOD 7), seed weight (LOD 4.6), seed oil content (LOD 6.6), number of siliques (LOD 3) and number of seeds per silique (LOD 3). There was only a significant positive correlation between seed colour and seed oil content in the yellow coloured classes. Seed coat colour and seed size were controlled by the maternal plant genotype. Plants with more siliques tended to have more, but smaller, seeds and higher seed oil content. Seed colour and seed oil content appeared to be controlled by two closely linked loci in repulsion phase. Thus, it may not always be advantageous to select for yellow-seededness when breeding for high seed oil content in Brassicas.
Safety of Novel Protein Sources (Insects, Microalgae, Seaweed, Duckweed, and Rapeseed) and Legislative Aspects for Their Application in Food and Feed Production
Spiegel, M. van der; Noordam, M.Y. ; Fels-Klerx, H.J. van der - \ 2013
Comprehensive Reviews in Food Science and Food Safety 12 (2013)6. - ISSN 1541-4337 - p. 662 - 678.
culturing aquatic organisms - cross-reactive allergen - sludge-grown algae - lemna-minor l. - heavy-metals - chemical-composition - atopic-dermatitis - edible insects - oilseed rape - turnip rape
Novel protein sources (like insects, algae, duckweed, and rapeseed) are expected to enter the European feed and food market as replacers for animal-derived proteins. However, food safety aspects of these novel protein sources are not well-known. The aim of this article is to review the state of the art on the safety of major novel protein sources for feed and food production, in particular insects, algae (microalgae and seaweed), duckweed, and rapeseed. Potential hazards for these protein sources are described and EU legislative requirements as regard to food and feed safety are explained. Potential hazards may include a range of contaminants, like heavy metals, mycotoxins, pesticide residues, as well as pathogens. Some safety aspects of novel protein sources are intrinsic to the product, but many potential hazards can also be due to production methods and processing conditions. These aspects should be considered in advance during product development. European law is unclear on several issues regarding the use of novel protein sources in food and feed products. For food product applications, the most important question for food producers is whether or not the product is considered a novel food. One of the major unclarities for feed applications is whether or not products with insects are considered animal-derived products or not. Due to the unclarities in European law, it is not always clear which Regulation and maximum levels for contaminants apply. For market introduction, European legislation should be adjusted and clarified.
European Perspectives on the Adoption of Nonchemical Weed Management in Reduced-Tillage Systems for Arable Crops
Melander, B. ; Munier-Jolain, N.M. ; Charles, R. ; Wirth, J. ; Schwarz, J. ; Weide, R.Y. van der; Bonin, L. ; Jensen, P.K. ; Kudsk, P.K. - \ 2013
Weed Technology 27 (2013)1. - ISSN 0890-037X - p. 231 - 240.
thistle cirsium-arvense - population-dynamics - oilseed rape - no-till - alopecurus-myosuroides - herbicide performance - conservation tillage - cropping systems - stubble tillage - spring barley
Noninversion tillage with tine- or disc-based cultivations prior to crop establishment is the most common way of reducing tillage for arable cropping systems with small grain cereals, oilseed rape, and maize in Europe. However, new regulations on pesticide use might hinder further expansion of reduced-tillage systems. European agriculture is asked to become less dependent on pesticides and promote crop protection programs based on integrated pest management (IPM) principles. Conventional noninversion tillage systems rely entirely on the availability of glyphosate products, and herbicide consumption is mostly higher compared to plow-based cropping systems. Annual grass weeds and catchweed bedstraw often constitute the principal weed problems in noninversion tillage systems, and crop rotations concurrently have very high proportions of winter cereals. There is a need to redesign cropping systems to allow for more diversification of the crop rotations to combat these weed problems with less herbicide input. Cover crops, stubble management strategies, and tactics that strengthen crop growth relative to weed growth are also seen as important components in future IPM systems, but their impact in noninversion tillage systems needs validation. Direct mechanical weed control methods based on rotating weeding devices such as rotary hoes could become useful in reduced-tillage systems where more crop residues and less workable soils are more prevalent, but further development is needed for effective application. Owing to the frequent use of glyphosate in reduced-tillage systems, perennial weeds are not particularly problematic. However, results from organic cropping systems clearly reveal that desisting from glyphosate use inevitably leads to more problems with perennials, which need to be addressed in future research.
Are plant diseases too much ignored in the climate change debate?
Boonekamp, P.M. - \ 2012
European Journal of Plant Pathology 133 (2012)1. - ISSN 0929-1873 - p. 291 - 294.
phoma stem canker - oilseed rape
Ignoring plant diseases misinforms the climate change and food security debate. Diseases are expected not only to cause more severe crop loss in many areas in the world and threaten food security, but also to decrease the climate change mitigation capacity of forests, of other natural ecosystems and of producing crops. However, if research, policy and industry join forces to obtain the multidisciplinary knowledge necessary to adapt integrated pest management (IPM) to the changing climate, it is expected that sufficiently resilient cropping systems can be developed in time. This was the main conclusion of the International Conference on Climate Change and Plant Disease Management held in Evora, Portugal, in November 2010
Effector diversification within compartments of the Leptosphaeria maculans genome affected by repeat induced point mutations
Rouxel, T. ; Grandaubert, J. ; Hane, J.K. ; Hoede, C. ; Wouw, A. ; Couloux, A. ; Dominguez, V. ; Anthouard, V. ; Bally, P. ; Bourras, S. ; Cozijnsen, A.J. ; Ciuffetti, L.M. ; Degrave, A. ; Dilmaghani, A. ; Duret, L. ; Fudal, L. ; Goodwin, S.B. ; Gout, L. ; Glaser, N. ; Linglin, J. ; Kema, G.H.J. ; Lapalu, N. ; Lawrence, C.B. ; May, K. ; Meyer, M. ; Ollivier, B. ; Poulain, J. ; Schoch, C.L. ; Simon, A. ; Spatafora, J.W. ; Stachowiak, A. ; Turgeon, B.G. ; Tyler, B.M. ; Vincent, D. ; Weissenbach, J. ; Amselem, J. ; Quesneville, H. ; Oliver, R.P. ; Wincker, P. ; Balesdent, M.H. ; Howlett, B.J. - \ 2011
Nature Communications 2 (2011). - ISSN 2041-1723 - p. 202 - 202.
transposable elements - molecular evolution - pathogen effectors - brassica-napus - gene-transfer - oilseed rape - stem canker - avirulence - plant - fungal
Fungi are of primary ecological, biotechnological and economic importance. Many fundamental biological processes that are shared by animals and fungi are studied in fungi due to their experimental tractability. Many fungi are pathogens or mutualists and are model systems to analyse effector genes and their mechanisms of diversification. In this study, we report the genome sequence of the phytopathogenic ascomycete Leptosphaeria maculans and characterize its repertoire of protein effectors. The L. maculans genome has an unusual bipartite structure with alternating distinct guanine and cytosine-equilibrated and adenine and thymine (AT)-rich blocks of homogenous nucleotide composition. The AT-rich blocks comprise one-third of the genome and contain effector genes and families of transposable elements, both of which are affected by repeat-induced point mutation, a fungal-specific genome defence mechanism. This genomic environment for effectors promotes rapid sequence diversification and underpins the evolutionary potential of the fungus to adapt rapidly to novel host-derived constraints
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.
Survival of pathogens of Brussels sprouts (Brassica oleracea Gemifera group) in crop residues
Köhl, J. ; Vlaswinkel, M.E.T. ; Groenenboom-de Haas, B.H. ; Kastelein, P. ; Hoof, R.A. van; Wolf, J.M. van der; Krijger, M.C. - \ 2011
Plant Pathology 60 (2011)4. - ISSN 0032-0862 - p. 661 - 670.
alternaria-brassicae - mycosphaerella-brassicicola - venturia-inaequalis - primary inoculum - oilseed rape - leaf-litter - debris - soil - management - ascospores
Mycosphaerella brassicicola (ringspot), Alternaria brassicicola and A. brassicae (dark leaf spot) and Xanthomonas campestris pv. campestris (black spot) can infect leaves of Brussels sprouts resulting in yield losses. Infections of outer leaves of sprouts cause severe losses in quality. Crop residues can be a major primary inoculum source of the pathogens. Their population dynamics were followed in residues of leaves and stalks of crops of Brussels sprouts during 24 months using real-time PCR assays. Leaf residues on the soil surface or buried in soil decomposed within 4 months. However, residues of stalks were present in the field after 24 months. In such residues, M. brassicicola populations increased during the first 2 months, but decreased thereafter and the pathogen was found only occasionally in the second year. Alternaria brassicicola multiplied on stalks exposed on the surface of field soil and was present on such residues after 24 months. Survival was less on residues buried in soil. Alternaria brassicae population increased in stalks exposed on the soil surface during the first months but decreased thereafter under the detection limit. Xanthomonas campestris cv. campestris populations fluctuated in time but 1 × 104 cells mg-1 stalk residue were still found after 24 months. Additionally, the four pathogens were present in residues of 11 commercial rapeseed crops that were analysed. The observed variation in population sizes of the pathogens between individual pieces of crop residues indicates a stochastic spread of pathogens. Unravelling the underlying processes will support the development of novel methods for sustainable disease prevention.
Chemical espionage on species-specific butterfly anti-aphrodisiacs by hitchhiking Trichogramma wasps
Huigens, M.E. ; Woelke, J.B. ; Pashalidou, F.G. ; Bukovinszky, T. ; Smid, H.M. ; Fatouros, N.E. - \ 2010
Behavioral Ecology 21 (2010). - ISSN 1045-2249 - p. 470 - 478.
podisus-maculiventris hemiptera - weevil ceutorhynchus-assimilis - rape brassica-napus - sex-pheromone - oilseed rape - entomophagous insects - parasitic wasps - egg parasitoids - foraging behavior - infochemical use
Parasitic wasps employ a wide range of chemical cues to find their hosts. Very recently, we discovered how 2 closely related egg parasitoids, Trichogramma brassicae and Trichogramma evanescens, exploit the anti-aphrodisiac pheromone benzyl cyanide of one of their hosts, the gregarious large cabbage white butterfly Pieris brassicae that deposits a clutch of more than 20 eggs per oviposition bout. The pheromone is transferred by male butterflies to females during mating to enforce female monogamy. On detecting the anti-aphrodisiac, the tiny parasitic wasps ride on a mated female butterfly to a host plant and then parasitize her freshly laid eggs. The present study demonstrates that both wasp species similarly exploit the anti-aphrodisiac mixture of methyl salicylate and indole of another host, the more common solitary small cabbage white butterfly Pieris rapae that deposits only one egg at a time. Interestingly, this behavior is innate in T. brassicae, whereas T. evanescens learns it after one successful ride on a mated female butterfly. Moreover, we show that the wasps only respond to the anti-aphrodisiacs of the 2 cabbage white butterflies when the ubiquitous compounds are part of a complete mated female odor blend. Obviously, parasitic wasps use the sophisticated espionage-and-ride strategy to find eggs of different gregarious and solitary host species. From the wasps’ perspective there seems to be a trade-off between the abundance and egg-laying behavior of the butterflies. Our findings suggest that Pieris butterflies are under strong selective pressure to minimize the use of an anti-aphrodisiac.
Measuring the accuracy of agro-environmental in dicators
Makowski, D. ; Tichit, M. ; Guichard, L. ; Keulen, H. van; Beaudoin, N. - \ 2009
Journal of Environmental Management 90 (2009). - ISSN 0301-4797 - p. S139 - S146.
oilseed rape - management - models - livestock - nitrogen - systems - impact - crops - birds - risk
Numerous agro-environmental indicators have been developed by agronomists and ecologists during the last 20 years to assess the environmental impact of farmers’ practices, and to monitor effects of agro-environmental policies. The objectives of this paper were (i) to measure the accuracy of a wide range of agro-environmental indicators from experimental data and (ii) to discuss the value of different information typically used by these indicators, i.e. information on farmers’ practices, and on plant and soil characteristics. Four series of indicators were considered in this paper: indicators of habitat quality for grassland bird species, indicators of risk of disease in oilseed rape crops, indicators of risk of pollution by nitrogen fertilizer, and indicators of weed infestation. Several datasets were used to measure their accuracy in cultivated plots and in grasslands. The sensitivity, specificity, and probability of correctly ranking plots were estimated for each indicator. Our results showed that the indicators had widely varying levels of accuracy. Some show very poor performance and had no discriminatory ability. Other indicators were informative and performed better than random decisions. Among the tested indicators, the best ones were those using information on plant characteristics such as grass height, fraction of diseased flowers, or crop yield. The statistical method applied in this paper could support researchers, farm advisers, and decision makers in comparing various indicators.
Root and shoot glucosinolates: a comparison of their diversity, function and interactions in natural and managed ecosystems
Dam, N.M. van; Tytgat, T.O.G. ; Kirkegaard, J.A. - \ 2009
Phytochemistry Reviews 8 (2009)1. - ISSN 1568-7767 - p. 171 - 186.
brassica break-crops - defense signaling pathways - in-vitro activity - arabidopsis-thaliana - methyl jasmonate - oilseed rape - 2-phenylethyl glucosinolate - 2-phenylethylisothiocyanate concentration - leptosphaeria-maculans - pratylenchus-neglectus
The role of glucosinolates in aboveground plant¿insect and plant¿pathogen interactions has been studied widely in both natural and managed ecosystems. Fewer studies have considered interactions between root glucosinolates and soil organisms. Similarly, data comparing local and systemic changes in glucosinolate levels after root- and shoot-induction are scarce. An analysis of 74 studies on constitutive root and shoot glucosinolates of 29 plant species showed that overall, roots have higher concentrations and a greater diversity of glucosinolates than shoots. Roots have significantly higher levels of the aromatic 2-phenylethyl glucosinolate, possibly related to the greater effectiveness and toxicity of its hydrolysis products in soil. In shoots, the most dominant indole glucosinolate is indol-3-ylglucosinolate, whereas roots are dominated by its methoxyderivatives. Indole glucosinolates were the most responsive after jasmonate or salicylate induction, but increases after jasmonate induction were most pronounced in the shoot. In general, root glucosinolate levels did not change as strongly as shoot levels. We postulate that roots may rely more on high constitutive levels of glucosinolates, due to the higher and constant pathogen pressure in soil communities. The differences in root and shoot glucosinolate patterns are further discussed in relation to the molecular regulation of glucosinolate biosynthesis, the within-tissue distribution of glucosinolates in the roots, and the use of glucosinolate-containing crops for biofumigation. Comparative studies of tissue-specific biosynthesis and regulation in relation to the biological interactions in aboveground and belowground environments are needed to advance investigations of the evolution and further utilization of glucosinolates in natural and managed ecosystems.
Role of glucosinolates in insect-plant relationships and multitrophic interactions
Hopkins, R.J. ; Dam, N.M. van; Loon, J.J.A. van - \ 2009
Annual Review of Entomology 54 (2009). - ISSN 0066-4170 - p. 57 - 83.
cabbage root fly - beetle psylliodes-chrysocephala - parasitoid diaeretiella-rapae - sawfly athalia-rosae - mustard oil bomb - oilseed rape - brassica-napus - arabidopsis-thaliana - plutella-xylostella - pieris-rapae
Glucosinolates present classical examples of plant compounds affecting insect-plant interactions. They are found mainly in the family Brassicaceae, which includes several important crops. More than 120 different glucosinolates are known. The enzyme myrosinase, which is stored in specialized plant cells, converts glucosinolates to the toxic isothiocyanates. Insect herbivores may reduce the toxicity of glucosinolates and their products by excretion, detoxification, or behavioral adaptations. Glucosinolates also affect higher trophic levels, via reduced host or prey quality or because specialist herbivores may sequester glucosinolates for their own defense. There is substantial quantitative and qualitative variation between plant genotypes, tissues, and ontogenetic stages, which poses specific challenges to insect herbivores. Even though glucosinolates are constitutive defenses, their levels are influenced by abiotic and biotic factors including insect damage. Plant breeders may use knowledge on glucosinolates to increase insect resistance in Brassica crops. State-of-the-art techniques, such as mutant analysis and metabolomics, are necessary to identify the exact role of glucosinolates. Acronyms and Definitions Constitutive defense: defense characteristics that are always expressed in the plant Induced defense: induced responses that reduce the negative fitness consequences of an attack by a pest or pathogen Induced response: change in chemical compound levels after damage by herbivores Multitrophic interactions: interactions that involve more than two trophic levels in a food web Sequestration: the active accumulation of material as a means of protection against organisms from a higher trophic level Synomone: an allelochemical that elicits a response from which both the originator and receiver benefit Token (or sign) stimulus: a stimulus by which an animal distinguishes an important object
Performance of specialist and generalist herbivores feeding on cabbage cultivars is not explained by glucosinolate profiles
Poelman, E.H. ; Galiart, R.J.F.H. ; Raaijmakers, C.E. ; Loon, J.J.A. van; Dam, N.M. van - \ 2008
Entomologia Experimentalis et Applicata 127 (2008)3. - ISSN 0013-8703 - p. 218 - 228.
rape brassica-napus - oilseed rape - phytophagous insects - plutella-xylostella - wild populations - diamondback moth - pieris-rapae - resistance - mustard - responses
Plants display a wide range of chemical defences that may differ in effectiveness against generalist and specialist insect herbivores. Host plant-specific secondary chemicals such as glucosinolates (GS) in Brassicaceae typically reduce the performance of generalist herbivores, whereas specialists have adaptations to detoxify these compounds. The concentration of glucosinolates may also alter upon herbivory, allowing the plant to tailor its response to specifically affect the performance of the attacking herbivore. We studied the performance of three Lepidoptera species, two specialists [Pieris rapae L. (Pieridae), Plutella xylostella L. (Yponomeutidae)] and one generalist [Mamestra brassicae L. (Noctuidae)], when feeding on eight cultivars of Brassica oleracea L. and a native congener (Brassica nigra L.) and related this to the GS content. We tested the hypotheses (i) that a generalist herbivore is more affected by high GS concentrations, and (ii) that generalist feeding has a stronger effect on GS levels. Although performance of the three herbivores was different on the B. oleracea cultivars, M. brassicae and P. xylostella had a similar ranking order of performance on the eight cultivars. In most of the cultivars, the concentration of indole GS was significantly higher after feeding by P. rapae or M. brassicae than after P. xylostella feeding. As a consequence, the total concentration of GS in the cultivars showed a different ranking order for each herbivore species. The generalist M. brassicae performed equally well as the specialist P. xylostella on cultivars with high concentrations of GS. Our findings suggest that secondary metabolites other than GSs or differences in nutrient levels affect performance of the species studied.
Biology and recent developments in the systematics of Phoma, a complex genus of major quarantine significance
Aveskamp, M.M. ; Gruyter, J. de; Crous, P.W. - \ 2008
Fungal Diversity 31 (2008). - ISSN 1560-2745 - p. 1 - 18.
polymerase-chain-reaction - maculans species complex - salal gaultheria-shallon - leptosphaeria-maculans - oilseed rape - didymella-bryoniae - stem canker - section plenodomus - dna-sequences - causal agent
Species of the coelomycetous genus Phoma are ubiquitously present in the environment, and occupy numerous ecological niches. More than 220 species are currently recognised, but the actual number of taxa within this genus is probably much higher, as only a fraction of the thousands of species described in literature have been verified in vitro. For as long as the genus exists, identification has posed problems to taxonomists due to the asexual nature of most species, the high morphological variability in vivo, and the vague generic circumscription according to the Saccardoan system. In recent years the genus was revised in a series of papers by Gerhard Boerema and co-workers, using culturing techniques and morphological data. This resulted in an extensive handbook, the ¿Phoma Identification Manual¿ which was published in 2004. The present review discusses the taxonomic revision of Phoma and its teleomorphs, with a special focus on its molecular biology and papers published in the post-Boerema era.
Genetic variation in defense chemistry in wild cabbages affects herbivores and their endoparasitoids
Gols, R. ; Wagenaar, R. ; Bukovinszky, T. ; Dam, N.M. van; Dicke, M. ; Bullock, J.M. ; Harvey, J.A. - \ 2008
Ecology 89 (2008)6. - ISSN 0012-9658 - p. 1616 - 1626.
4 trophic levels - brassica-oleracea - plant chemistry - glucosinolate concentrations - cotesia-congregata - high-mortality - oilseed rape - pieris-rapae - slow-growth - bottom-up
Populations of wild Brassica oleracea L. grow naturally along the Atlantic coastlines of the United Kingdom and France. Over a very small spatial scale (i.e.,
Performance of generalist and specialist herbivores and their endoparasitoids differs on cultivated and wild Brassica populations
Gols, G.J.Z. ; Bukovinszky, T. ; Dam, N.M. van; Dicke, M. ; Bullock, J.M. ; Harvey, J.A. - \ 2008
Journal of Chemical Ecology 34 (2008)2. - ISSN 0098-0331 - p. 132 - 143.
oilseed rape - plutella-xylostella - host-plant - glucosinolate content - cotesia-congregata - induced responses - natural enemies - trophic levels - pieris-rapae - oleracea
Through artificial selection, domesticated plants often contain modified levels of primary and secondary metabolites compared to their wild progenitors. It is hypothesized that the changed chemistry of cultivated plants will affect the performance of insects associated with these plants. In this paper, the development of several specialist and generalist herbivores and their endoparasitoids were compared when reared on a wild and cultivated population of cabbage, Brassica oleracea, and a recently established feral Brassica species. Irrespective of insect species or the degree of dietary specialization, herbivores and parasitoids developed most poorly on the wild population. For the specialists, plant population influenced only development time and adult body mass, whereas for the generalists, plant populations also affected egg-to-adult survival. Two parasitoid species, a generalist (Diadegma fenestrale) and a specialist (D. semiclausum), were reared from the same host (Plutella xylostella). Performance of D. semiclausum was closely linked to that of its host, whereas the correlation between survival of D. fenestrale and host performance was less clear. Plants in the Brassicaceae characteristically produce defense-related glucosinolates (GS). Levels of GS in leaves of undamaged plants were significantly higher in plants from the wild population than from the domesticated populations. Moreover, total GS concentrations increased significantly in wild plants after herbivory, but not in domesticated or feral plants. The results of this study reveal that a cabbage cultivar and plants from a wild cabbage population exhibit significant differences in quality in terms of their effects on the growth and development of insect herbivores and their natural enemies. Although cultivated plants have proved to be model systems in agroecology, we argue that some caution should be applied to evolutionary explanations derived from studies on domesticated plants, unless some knowledge exists on the history of the system under investigation.
Ammonia fluxes and derived canopy compensation points over non-fertilizes agricultural grassland in The Netherlands using the new gradient ammonia-high accuracy-monitor (Graham)
Wichink Kruit, R.J. ; Pul, J. ; Otjes, W.A.J. van; Hofschreuder, P. ; Jacobs, A.F.G. ; Holtslag, A.A.M. - \ 2007
Atmospheric Environment 41 (2007)6. - ISSN 1352-2310 - p. 1275 - 1287.
intensively managed grassland - surface-exchange fluxes - atmosphere exchange - oilseed rape - vegetation - models - leaves - nh3
During a measurement period from June till November 2004, ammonia fluxes above non-fertilized managed grassland in The Netherlands were measured with a Gradient Ammonia¿High Accuracy¿Monitor (GRAHAM). Compared with earlier ammonia measurement systems, the GRAHAM has higher accuracy and a quality control system. Flux measurements are presented for two different periods, i.e. a warm, dry summer period (from 18 July till 15 August) and a wet, cool autumn period (23 September till 23 October). From these measurements canopy compensation points were derived. The canopy compensation point is defined as the effective surface concentration of ammonia. In the summer period (negative) deposition fluxes are observed in the evening, night and early morning due to leaf surface wetness, while in the afternoon emission fluxes are observed due to high canopy compensation points. The mean NH3-flux in this period was 4 ng m¿2 s¿1, which corresponds to a net emission of 0.10 kg N ha¿1 over the 28 day sampling period. The NH3-flux in the autumn period mainly shows (negative) deposition fluxes due to small canopy compensation points caused by low temperatures and a generally wet surface. The mean NH3-flux in this period is ¿24 ng m¿2 s¿1, which corresponds to a net deposition of 0.65 kg N ha¿1 over the 31 day sampling period. Frequency distributions of the NH3-concentration and flux show that despite higher average ambient NH3-concentrations (13.3 ¿g m¿3 in the summer period vs. 6.4 ¿g m¿3 in the autumn period) there are more emission events in the summer period than in the autumn period (about 50% of the time in summer vs. 20% in autumn). This is caused by the high canopy compensation points in summer due to high temperatures and a dry surface. In autumn, deposition dominates due to a generally wet surface that induces low canopy compensation points. For our non-fertilized agricultural grassland site, the derived canopy compensation points (at temperatures between 7 and 29 °C) varied from 0.5 to 29.7 ¿g m¿3 and were on an average 7.0 ¿g m¿3, which is quite high for non-fertilized conditions and probably caused by high nitrogen inputs in the past or high dry deposition amounts from local sources. The average value for the ratio between NH4+ and H+ concentration in the canopy, ¿c, that was derived from our data was 2200.