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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    Next-generation biological control: the need for integrating genetics and genomics
    Leung, Kelley ; Ras, Erica ; Ferguson, Kim B. ; Ariëns, Simone ; Babendreier, Dirk ; Bijma, Piter ; Bourtzis, Kostas ; Brodeur, Jacques ; Bruins, Margreet A. ; Centurión, Alejandra ; Chattington, Sophie R. ; Chinchilla-Ramírez, Milena ; Dicke, Marcel ; Fatouros, Nina E. ; González-Cabrera, Joel ; Groot, Thomas V.M. ; Haye, Tim ; Knapp, Markus ; Koskinioti, Panagiota ; Hesran, Sophie Le; Lyrakis, Manolis ; Paspati, Angeliki ; Pérez-Hedo, Meritxell ; Plouvier, Wouter N. ; Schlötterer, Christian ; Stahl, Judith M. ; Thiel, Andra ; Urbaneja, Alberto ; Zande, Louis van de; Verhulst, Eveline C. ; Vet, Louise E.M. ; Visser, Sander ; Werren, John H. ; Xia, Shuwen ; Zwaan, Bas J. ; Magalhães, Sara ; Beukeboom, Leo W. ; Pannebakker, Bart A. - \ 2020
    Biological Reviews (2020). - ISSN 1464-7931
    artificial selection - biological control - genetics - genome assembly - genomics - insect breeding - microbiome - modelling

    Biological control is widely successful at controlling pests, but effective biocontrol agents are now more difficult to import from countries of origin due to more restrictive international trade laws (the Nagoya Protocol). Coupled with increasing demand, the efficacy of existing and new biocontrol agents needs to be improved with genetic and genomic approaches. Although they have been underutilised in the past, application of genetic and genomic techniques is becoming more feasible from both technological and economic perspectives. We review current methods and provide a framework for using them. First, it is necessary to identify which biocontrol trait to select and in what direction. Next, the genes or markers linked to these traits need be determined, including how to implement this information into a selective breeding program. Choosing a trait can be assisted by modelling to account for the proper agro-ecological context, and by knowing which traits have sufficiently high heritability values. We provide guidelines for designing genomic strategies in biocontrol programs, which depend on the organism, budget, and desired objective. Genomic approaches start with genome sequencing and assembly. We provide a guide for deciding the most successful sequencing strategy for biocontrol agents. Gene discovery involves quantitative trait loci analyses, transcriptomic and proteomic studies, and gene editing. Improving biocontrol practices includes marker-assisted selection, genomic selection and microbiome manipulation of biocontrol agents, and monitoring for genetic variation during rearing and post-release. We conclude by identifying the most promising applications of genetic and genomic methods to improve biological control efficacy.

    Efficacies of bacterial and fungal isolates in biocontrol of Botrytis cinerea and Pseudomonas syringae pv. tomato and growth promotion in tomato do not correlate
    Köhl, J. ; Vasconcelos de Medeiros, Flavio ; Plas, C.H. ; Haas, B.H. de; Bosch, G.B.M. van den - \ 2020
    Biological Control 150 (2020). - ISSN 1049-9644
    biological control - Antagonist - Bioassay - Grey mold - Bacterial spot - Solanum lycopersicon
    There is a need to develop more biological control agents to fulfil the increasing demand for biological crop protection. Testing for consistent efficacy in disease control under the relevant range of environmental conditions is one of the most demanding steps during screening programs. Bioassays were conducted to target three major diseases of tomato, stem canker caused by Botrytis cinerea, leaf spot caused by B. cinerea, and bacterial spot caused by Pseudomonas syringae pv. tomato, and to assess possible growth promotion of tomato seedlings. Nine quantitative screening approaches were analyzed for a test panel of approximately 100 isolates of bacteria and fungi, all obtained from tomato, and several known antagonists as reference isolates. Even with such a limited number of isolates promising antagonists, partly not yet described as antagonists, could be selected for control of the targeted diseases when labor and resource demanding in planta bioassays had been applied. Also some promising isolates enhancing seedling development could be identified. Independent screening assays for the different traits were needed since no correlation between the different traits were found. Attempts to simplify screening assays to high-throughput systems failed since there were no positive correlations with in planta bioassays. In conclusion, the often suggested first screening rounds using in vitro tests for huge numbers of isolates followed by in planta testing of a selected group of candidates, e.g. those with high in vitro production of certain secondary metabolites or biosurfactants, may not exploit the entire potential of antagonists. Especially antagonists combining various modes of action may be excluded by in vitro screening with a bias on a specific mode of action. Therefore, independent in planta assays are proposed to screen against different pathogens and for growth promotion.
    The contribution of semi-natural habitats to biological control is dependent on sentinel prey type
    McHugh, Niamh M. ; Moreby, Steve ; Lof, Marjolein E. ; Werf, Wopke Van der; Holland, John M. - \ 2020
    Journal of Applied Ecology 57 (2020)5. - ISSN 0021-8901 - p. 914 - 925.
    agroecology - aphids - biological control - ecosystem services - landscape ecology - semi-natural habitat - sentinel - surrogate prey

    It is widely recognized that landscape factors affect the biological control of weed seeds and insect pests in arable crops, but landscape effects have been found to be inconsistent between studies. Here, we compare six different types of sentinels (surrogate prey that was either live insects or seeds) to measure the effects of semi-natural habitats at field to landscape scales on levels of biological control in winter wheat in the UK. Sentinels were located in fields adjacent to three boundary types: grassy margin, hedgerows or woodland to study the local scale effects and in landscapes of varying heterogeneity in study areas of 1-km radius. Overall, mean levels of predation were higher for most insect prey (60.8%) located on the ground compared to the crop (12.2%) and was lower for seeds (5.8%). Predation of sentinels on the ground was attributed to generalist predators. Semi-natural habitats had both positive and negative effects at field and landscape scales, but the response varied with the sentinel type. Herbaceous linear semi-natural habitats had positive effects at local scales for Calliphora vomitoria and Sitobion avenae sentinels and provide evidence that farmers can introduce linear herbaceous features to benefit biological control. In contrast, our distance-weighted kernel models identified a positive relationship between woody habitats and the predation of C. vomitoria and Chenopodium album. Natural aphid infestations were lower in landscapes with more semi-natural habitat. Synthesis and applications. Sentinels may be sensitive enough to detect variation in levels of biological control influenced by semi-natural habitats, but this study confirms that landscape effects differ for different types of sentinel prey. This implies that it may not be possible to categorize landscapes as pest suppressive using a single sentinel type. Future studies should therefore consider using multiple sentinels to give a better perspective on predation intensity. The resulting recommendations for farm management include planting woodland adjacent wheat fields infested with seed predators and positioning herbaceous linear habitats adjacent wheat fields infested with Sitobion avenae, particularly if fields are bordered by woody liner habitats due to their association with decreased S. avenae predation.

    The potential of highly nutritious frozen stages of Tyrophagus putrescentiae as a supplemental food source for the predatory mite Amblyseius swirskii
    Pirayeshfar, Fatemeh ; Safavi, Seyed Ali ; Sarraf Moayeri, Hamid Reza ; Messelink, Gerben J. - \ 2020
    Biocontrol Science and Technology 30 (2020)5. - ISSN 0958-3157 - p. 403 - 417.
    astigmatid mites - biological control - frozen hosts - phytoseiidae - western flower thrips

    Astigmatid mites have potential as supplementary prey items to support generalist predator populations in crops. However, applying living prey mites has some disadvantages; if not predated they have the potential to cause crop damage and allergies. In this study, we evaluated various diets based on the astigmatid mite Tyrophagous putrescentiae (Schrank) as a supplemental food source for the predatory mite Amblyseius swirskii Ahias-Henriot. Eggs and larvae of T. putrescentiae were reared on a diet of dog food (rich in proteins and fat) or bran (rich in carbohydrate); they were offered either frozen or alive, and either with or without cattail pollen (Typha angustifolia L.). Oviposition rate of A. swirskii fed with frozen mite larvae reared on dog food was similar to the rate observed when they were fed with cattail pollen or living prey mites, but developmental time of A. swirskii was longer on this frozen diet than on a diet of living prey mites or pollen. Both living and frozen prey mites were, in contrast with cattail pollen, not suitable for oviposition by western flower thrips, Frankliniella occidentalis Pergande. In a greenhouse study, the use of frozen prey mite stages as supplemental food on chrysanthemum plants allowed populations of A. swirskii to establish, but not increase; in contrast, provision of living prey mites and pollen increased A. swirskii populations on plants. Hence, our study shows that living prey mites, but not frozen prey mites, had the greatest potential as a supplemental food source for A. swirskii.

    The omnivorous predator Macrolophus pygmaeus, a good candidate for the control of both greenhouse whitefly and poinsettia thrips on gerbera plants
    Leman, Ada ; Ingegno, Barbara L. ; Tavella, Luciana ; Janssen, Arne ; Messelink, Gerben J. - \ 2020
    Insect Science 27 (2020)3. - ISSN 1672-9609 - p. 510 - 518.
    apparent competition - biological control - Echinothrips americanus - pest interactions - prey preference - Trialeurodes vaporariorum

    The poinsettia thrips Echinothrips americanus Morgan is a relatively new pest that has spread rapidly worldwide and causes serious damage in both vegetable and ornamental plants. In this study, we investigated if and how effective this pest can be controlled in gerbera by the omnivorous predator Macrolophus pygmaeus (Rambur). Because herbivores on plants can interact through a shared predator, we also investigated how poinsettia thrips control is affected by the presence of the greenhouse whitefly Trialeurodes vaporariorum (Westwood), a pest that commonly coexists with E. americanus in gerbera. In laboratory studies, we found that the predator M. pygmaeus fed on both pests when offered together. Olfactometer tests showed a clear preference of the predators for plants infested by whiteflies but not by thrips. In a greenhouse experiment, densities of both pests on single gerbera plants were reduced to very low levels by the predator, either with both pests present together or alone. Hence, predator-mediated effects between whiteflies and thrips played only a minor role. The plant feeding of the shared predator probably reduced the dependence of predator survival and reproduction on the densities of the two pests, thereby weakening potential predator-mediated effects. Thus, M. pygmaeus is a good candidate for biological control of both pests in gerbera. However, further research is needed to investigate pest control at larger scales, when the pests can occur on different plants.

    Archived experimental data on heritability of wing truncation in flightless Adalia bipunctata
    Lommen, Suzanne T.E. ; Koops, Kees G. ; Cornelder, Bardo A. ; Jong, Peter W. de; Brakefield, Paul M. - \ 2019
    Wageningen University & Research
    Adalia bipunctata - artificial selection - biological control - breeding design - Coccinellidae - Coleoptera - flightless - genetics - heritability - ladybird beetle - natural enemy - selective breeding - wing length - winglessness
    Original empirical data published in Lommen STE, Koops CG et al. 2019 Genetics and selective breeding of variation in wing truncation in a flightless aphid control agent. Entomologia Experimentalis et Applicata 167: 636-645. doi:10.1111/eea.12810
    Genetics and selective breeding of variation in wing truncation in a flightless aphid control agent
    Lommen, Suzanne T.E. ; Koops, Kees G. ; Cornelder, Bardo A. ; Jong, Peter W. de; Brakefield, Paul M. - \ 2019
    Entomologia Experimentalis et Applicata 167 (2019)7. - ISSN 0013-8703 - p. 636 - 645.
    Adalia bipunctata - artificial selection - augmentative pest control - biological control - Coccinellidae - Coleoptera - cryptic genetic variation - gene-by-environment interaction - ladybird - modifier genes - predator - winglessness

    Augmentative biological control by predaceous ladybird beetles can be improved by using flightless morphs, which have longer residence times on the host plants. The two-spot ladybird beetle, Adalia bipunctata (L.) (Coleoptera: Coccinellidae), is used for the biological control of aphids in greenhouses and on urban trees. Flightlessness due to truncated wings occurs at very low frequency in some natural populations of A. bipunctata. Pure-breeding strains of this 'wingless' genotype of A. bipunctata can easily be obtained in the laboratory. Such strains have not been commercialized yet due to concerns about their reduced fitness compared to wild-type strains, which renders mass production more expensive. Wingless strains exhibit, however, wide intra-population phenotypic variation in the extent of wing truncation which is related to fitness traits. We here use classical quantitative genetic techniques to study the heritability and genetic architecture of variation in wing truncation in a wingless strain of A. bipunctata. Split-families reared at one of two temperatures revealed strong family-by-temperature interaction: heritability was estimated as 0.64 ± 0.09 at 19 °C and 0.29 ± 0.06 at 29 °C. Artificial selection in opposite directions at 21 °C demonstrated that the degree of wing truncation can be altered within a few generations resulting in wingless phenotypes without any wing tissue (realized h2 = 0.72), as well as those with minimal truncations (realized h2 = 0.61) in two replicates. The latter lines produced more than twice as many individuals. This indicates that selective breeding of wing truncation may be exploited to improve mass rearing of flightless strains of A. bipunctata for commercial biological control. Our work illustrates that cryptic variation can also be a source for the selective breeding of natural enemies.

    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.
    Genetic variation of biological control relevant traits in natural enemies: a systematic review, supporting data
    Pannebakker, Bart ; Ferguson, Kimberley - \ 2019
    Wageningen University & Research
    genome - biocontrol - biological control - parasitoid - predator - heritability - genetic variation
    This is supplementary material for a systematic review tentatively titled, "Genetic variation of biological control relevant traits in natural enemies: a systematic review" (2019). Three tables are available, and are referenced in the following manner in text: Table S1: Positive control group for search results, based on papers that fit the ideal search returns for the search term. Table S2: Combined search return hits, in unedited format received from CAB Abstracts. Table S3: Articles narrowed down to BCA, with duplicates and unavailable papers removed, prior to assessment for estimation method and traits.
    Pest kill rate as aggregate evaluation criterion to rank biological control agents: A case study with Neotropical predators of Tuta absoluta on tomato
    Lenteren, J.C. Van; Bueno, V.H.P. ; Burgio, G. ; Lanzoni, A. ; Montes, F.C. ; Silva, D.B. ; Jong, P.W. De; Hemerik, L. - \ 2019
    Bulletin of Entomological Research 109 (2019)6. - ISSN 0007-4853 - p. 812 - 820.
    biological control - Campyloneuropsis infumatus - Engytatus varians - Macrolophus basicornis - Miridae - natural enemy efficacy - natural enemy evaluation criteria - South American tomato moth

    Tuta absoluta (Meyrick), a key pest of tomato, is quickly spreading over the world and biological control is considered as one of the control options. Worldwide more than 160 species of natural enemies are associated with this pest, and an important challenge is to quickly find an effective biocontrol agent from this pool of candidate species. Evaluation criteria for control agents are presented, with the advantages they offer for separating potentially useful natural enemies from less promising ones. Next, an aggregate parameter for ranking agents is proposed: the pest kill rate k m . We explain why the predator's intrinsic rate of increase cannot be used for comparing the control potential of predators or parasitoids, while k m can be used to compare both types of natural enemies. As an example, kill rates for males, females and both sexes combined of three Neotropical mirid species (Campyloneuropsis infumatus (Carvalho), Engytatus varians (Distant) and Macrolophus basicornis (Stål)) were determined, taking all life-history data (developmental times, survival rates, total nymphal and adult predation, sex ratios and adult lifespan) into account. Based on the value for the intrinsic rate of increase (r m ) for T. absoluta and for the kill rate k m of the predators, we predict that all three predators are potentially able to control the pest, because their k m values are all higher than the r m of the pest. Using only k m values, we conclude that E. varians is the best candidate for control of T. absoluta on tomato, with C. infumatus ranking second and M. basicornis last.

    The interplay of landscape composition and configuration: new pathways to manage functional biodiversity and agroecosystem services across Europe
    Martin, Emily A. ; Dainese, Matteo ; Clough, Yann ; Báldi, András ; Bommarco, Riccardo ; Gagic, Vesna ; Garratt, Michael P.D. ; Holzschuh, Andrea ; Kleijn, David ; Kovács-Hostyánszki, Anikó ; Marini, Lorenzo ; Potts, Simon G. ; Smith, Henrik G. ; Hassan, Diab Al; Albrecht, Matthias ; Andersson, Georg K.S. ; Asís, Josep D. ; Aviron, Stéphanie ; Balzan, Mario V. ; Baños-Picón, Laura ; Bartomeus, Ignasi ; Batáry, Péter ; Burel, Francoise ; Caballero-López, Berta ; Concepción, Elena D. ; Coudrain, Valérie ; Dänhardt, Juliana ; Diaz, Mario ; Diekötter, Tim ; Dormann, Carsten F. ; Duflot, Rémi ; Entling, Martin H. ; Farwig, Nina ; Fischer, Christina ; Frank, Thomas ; Garibaldi, Lucas A. ; Hermann, John ; Herzog, Felix ; Inclán, Diego ; Jacot, Katja ; Jauker, Frank ; Jeanneret, Philippe ; Kaiser, Marina ; Krauss, Jochen ; Féon, Violette Le; Marshall, Jon ; Moonen, Anna Camilla ; Moreno, Gerardo ; Riedinger, Verena ; Rundlöf, Maj ; Rusch, Adrien ; Scheper, Jeroen ; Schneider, Gudrun ; Schüepp, Christof ; Stutz, Sonja ; Sutter, Louis ; Tamburini, Giovanni ; Thies, Carsten ; Tormos, José ; Tscharntke, Teja ; Tschumi, Matthias ; Uzman, Deniz ; Wagner, Christian ; Zubair-Anjum, Muhammad ; Steffan-Dewenter, Ingolf - \ 2019
    Ecology Letters 22 (2019)7. - ISSN 1461-023X - p. 1083 - 1094.
    Agroecology - arthropod community - biological control - edge density - pest control - pollination - response trait - semi-natural habitat - trait syndrome - yield

    Managing agricultural landscapes to support biodiversity and ecosystem services is a key aim of a sustainable agriculture. However, how the spatial arrangement of crop fields and other habitats in landscapes impacts arthropods and their functions is poorly known. Synthesising data from 49 studies (1515 landscapes) across Europe, we examined effects of landscape composition (% habitats) and configuration (edge density) on arthropods in fields and their margins, pest control, pollination and yields. Configuration effects interacted with the proportions of crop and non-crop habitats, and species’ dietary, dispersal and overwintering traits led to contrasting responses to landscape variables. Overall, however, in landscapes with high edge density, 70% of pollinator and 44% of natural enemy species reached highest abundances and pollination and pest control improved 1.7- and 1.4-fold respectively. Arable-dominated landscapes with high edge densities achieved high yields. This suggests that enhancing edge density in European agroecosystems can promote functional biodiversity and yield-enhancing ecosystem services.

    Biological control of an invasive pest eases pressures on global commodity markets
    Wyckhuys, K.A.G. ; Zhang, W. ; Prager, S.D. ; Kramer, D.B. ; Delaquis, E. ; Gonzalez, C.E. ; Werf, W. van der - \ 2018
    Environmental Research Letters 13 (2018)9. - ISSN 1748-9318
    biological control - ecosystem services - invasion biology - social-ecological systems - sustainable intensification - tele-coupling

    In an increasingly globalized world, invasive species cause major human, financial, and environmental costs. A cosmopolitan pest of great concern is the cassava mealybug Phenacoccus manihoti (Hemiptera: Pseudococcidae), which invaded Asia in 2008. Following its arrival, P. manihoti inflicted measurable yield losses and a 27% drop in aggregate cassava production in Thailand. As Thailand is a vital exporter of cassava-derived commodities to China and supplies 36% of the world's internationally-traded starch, yield shocks triggered price surges and structural changes in global starch trade. In 2009 a biological control agent was introduced in Asia-the host-specific parasitoid, Anagyrus lopezi (Hymenoptera: Encyrtidae). This parasitoid had previously controlled the cassava mealybug in Africa, and its introduction in Asia restored yield levels at a continent-wide scale. Trade network and price time-series analyses reveal how both mealybug-induced production loss and subsequent parasitoid-mediated yield recovery coincided with price fluctuations in futures and spot markets, with important cascading effects on globe-spanning trade networks of (cassava) starch and commodity substitutes. While our analyses may not imply causality, especially given the concurrent 2007-2011 food crises, our results do illuminate the important interconnections among subcomponents of the global commodity system. Our work underlines how ecologically-based tactics support resilience and safeguard primary productivity in (tropical) agro-ecosystems, which in turn help stabilize commodity markets in a similar way as pesticide-centered approaches. Yet, more importantly, (judiciously-implemented) biological control can deliver ample 'hidden' environmental and human-health benefits that are not captured by the prices of globally-traded commodities.

    Data from: Crop pests and predators exhibit inconsistent responses to surrounding landscape composition
    Karp, Daniel S. ; Chaplin-Kramer, Rebecca ; Meehan, Timothy D. ; Martin, Emily A. ; DeClerck, Fabrice ; Grab, Heather ; Gratton, Claudio ; Hunt, Lauren ; Larsen, Ashley E. ; Martínez-Salinas, Alejandra ; Bianchi, F.J.J.A. ; Werf, W. van der - \ 2018
    University of California
    agroecology - biological control - natural enemies - pest control - pest - ecosystem services - landscape
    The idea that noncrop habitat enhances pest control and represents a win–win opportunity to conserve biodiversity and bolster yields has emerged as an agroecological paradigm. However, while noncrop habitat in landscapes surrounding farms sometimes benefits pest predators, natural enemy responses remain heterogeneous across studies and effects on pests are inconclusive. The observed heterogeneity in species responses to noncrop habitat may be biological in origin or could result from variation in how habitat and biocontrol are measured. Here, we use a pest-control database encompassing 132 studies and 6,759 sites worldwide to model natural enemy and pest abundances, predation rates, and crop damage as a function of landscape composition. Our results showed that although landscape composition explained significant variation within studies, pest and enemy abundances, predation rates, crop damage, and yields each exhibited different responses across studies, sometimes increasing and sometimes decreasing in landscapes with more noncrop habitat but overall showing no consistent trend. Thus, models that used landscape-composition variables to predict pest-control dynamics demonstrated little potential to explain variation across studies, though prediction did improve when comparing studies with similar crop and landscape features. Overall, our work shows that surrounding noncrop habitat does not consistently improve pest management, meaning habitat conservation may bolster production in some systems and depress yields in others. Future efforts to develop tools that inform farmers when habitat conservation truly represents a win–win would benefit from increased understanding of how landscape effects are modulated by local farm management and the biology of pests and their enemies.
    Uncovering the economic value of natural enemies and true costs of chemical insecticides to cotton farmers in China
    Huang, Jikun ; Zhou, Ke ; Zhang, Wei ; Deng, Xiangzheng ; Der Werf, Wopke van; Lu, Yanhui ; Wu, Kongming ; Rosegrant, Mark W. - \ 2018
    Environmental Research Letters 13 (2018)6. - ISSN 1748-9318
    biological control - economic value - insecticides - natural enemies - smallholder farming

    Little empirical evidence on the economic value of biological control of pests at farm level is available to improve economic decision-making by farmers and policy makers. Using insect sampling and household survey in an integrated bio-economic analysis framework, this paper studies farmers' crop management practices in cotton in the North China Plain, and estimates the marginal value of natural enemies and costs of chemical insecticides to farmers. Ladybeetles (mainly Harmonia axyridis, Propylea japonica, and Coccinella septempunctata), the dominant natural enemy group that controls the primary pest (aphid) in cotton in our study area, provide a significant economic benefit that is unknown to the farmers. Even at the current high levels of insecticide use, an additional ladybeetle provides an economic benefit of 0.05 CNY (almost USD 0.01) to farmers. The use of broad-spectrum insecticides by farmers is alarmingly excessive, not only undermining farmers' cotton profitability but also inducing social costs as well as disruption of the natural pest suppression system. Doubling current ladybeetle density in cotton field could gain an estimated USD 300 million for cotton farmers in China, providing a strong economic case for policies to move the pest control system towards a more ecologically-based regime, with positive consequences for farm income and environmental health. With rising use of biological control service provided by natural enemies such as ladybeetles in cotton fields, significant falls in farmers' insecticide use would be expected, which could raise the value of ladybeetles and other natural enemies even further. The results indicate that there is an urgent need to rationalize inputs and move forward to improved agro-ecosystem management in smallholder farming system. Raising knowledge and awareness on the costs and value of biological pest control versus insecticides among farmers and policy makers and having effective extension service, are priorities towards achieving a more ecologically-based approach to crop protection on smallholder farms.

    Kleine lieveheersbeestjes bieden perspectief tegen luizenprobleem: nuttig bij preventie van grote luisuitbraken
    Messelink, G.J. - \ 2017
    biological control - biological control agents - natural enemies - aphididae - greenhouse horticulture - sweet peppers - organic farming - propylea quatuordecimpunctata
    Mothers in the woods: multitrophic interactions and oviposition preference in the bronze big Thaumastocoris pergrinus, a pest of Eucalyptus
    Martínez, Gonzalo - \ 2017
    Wageningen University. Promotor(en): M. Dicke, co-promotor(en): A. González. - Wageningen : Wageningen University - ISBN 9789463436786 - 172
    eucalyptus - forest plantations - forest pests - multitrophic interactions - biological control - hemiptera - oviposition - host plants - uruguay - insect plant relations - eucalyptus - bosplantages - bosplagen - multitrofe interacties - biologische bestrijding - hemiptera - ovipositie - waardplanten - uruguay - insect-plant relaties

    The bronze bug is an important pest of Eucalyptus trees. Originally restricted to Australia, it has become an important pest of Eucalyptus plantations, colonizing in 15 years the major production areas worldwide. The aim of this thesis was to investigate the factors affecting the oviposition behavior of the bronze bug within a multitrophic system comprised of its host plant (Eucalyptus spp.), a common co-occurring sap-feeder (Glycaspis brimblecombei) and a specialist egg parasitoid (Cleruchoides noackae). I assessed the life parameters of this species in a newly developed rearing. Based on the preference-performance hypothesis, I tested the effects of host-plant quality, conspecifics, or the infestation by a potential competitor on preference-performance correlations of the bronze bug. The egg parasitoid (C. noackae) was introduced, reared, and released. Finally, I assessed host-selection behavior of the parasitoid, testing its responses towards different contact cues. The findings of this investigation provided new insights on the oviposition behavior by true bugs, and towards the development of management strategies for T. peregrinus.

    Management of water hyacinth (Eichhornia crassipes [Mart.] Solms) using bioagents in the Rift Valley of Ethiopia
    Gebregiorgis, Firehun Yirefu - \ 2017
    Wageningen University. Promotor(en): Paul Struik, co-promotor(en): Egbert Lantinga; Taye Tessema. - Wageningen : Wageningen University - ISBN 9789463430562 - 174
    eichhornia crassipes - biological control agents - biological control - neochetina - curculionidae - mycoherbicides - ethiopia - eichhornia crassipes - organismen ingezet bij biologische bestrijding - biologische bestrijding - neochetina - curculionidae - mycoherbiciden - ethiopië

    This thesis presents a study on management of water hyacinth (Eichhornia crassipes [Mart.] Solms) using insects and fungal pathogens as bioagents. The main goal was to develop an effective biocontrol strategy for water hyacinth in the Rift Valley of Ethiopia. To this end, a field survey was conducted to assess the agro-ecological distribution of water hyacinth and of native fungal pathogens found in association with water hyacinth. We also performed laboratory and lath house experiments on (i) pathogenicity and host specificity of the fungal pathogens; (ii) adaptability, life table, efficacy and host specificity of the two Neochetina weevils; and (iii) the synergetic effects of integrated use of Neochetina weevils and fungal pathogen as bioagents. Survey results indicated that the weed is distributed in the Rift Valley water bodies located in low, mid and high altitude. The survey results also identified 25 fungal species found in association with water hyacinth that belonged to nine genera. Among the isolates, Alternaria alternata, A. tenuissima, and Alternaria spp. hold promise as possible bioagents of water hyacinth.

    Laboratory study on life cycle and development of Neochetina weevils indicated the two weevils took shorter generation time in Ethiopia than in Argentina but relatively similar to Kenya and Uganda. In Ethiopia, the two weevils produced four generations per year indicating their successful establishment. Feeding by adult weevils and tunneling by larvae significantly impacted the vigour and reproduction of water hyacinth plants. A herbivory loads of three pairs of N. bruchi and two pairs of N. eichhorniae showed the highest level of leaf damage and defoliated petioles. The study also reinforced that the two weevils are sufficiently host-specific. Finally, a study on integrated use of Neochetina weevils and an indigenous plant pathogen revealed that the two Neochetina weevils and the fungus A. alternata were together able to reduce the vegetative growth and fresh weight of water hyacinth plants considerably.

    This study recommends integrated use of fungal species and the two weevils to control water hyacinth. Implications of the findings are also discussed in the context of integrated water hyacinth management using the native fungal pathogens and the two weevils.

    Fusarium is toenemend probleem in teelt van amaryllis : drie ziekteverwekkers en doorelkaar lopende symptomen
    Kromwijk, Arca - \ 2016
    fusarium - plant diseases - plant disease control - plant pathogens - plant protection - greenhouse horticulture - amaryllis - biological control
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