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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    Phytophagy on phylogenetically isolated trees: why hosts should escape their relatives.
    Yguel, B. ; Bailey, R. ; Everhart, D. ; Vialatte, A. ; Vasseur, C. ; Vitrac, X. ; Prinzing, A. - \ 2011
    Ecology Letters 14 (2011)11. - ISSN 1461-023X - p. 1117 - 1124.
    bark volatiles - plants - herbivory - insects - lepidoptera - diversity - evolution - specialization - conservatism - tortricidae
    Hosts belonging to the same species suffer dramatically different impacts from their natural enemies. This has been explained by host neighbourhood, that is, by surrounding host-species diversity or spatial separation between hosts. However, even spatially neighbouring hosts may be separated by many million years of evolutionary history, potentially reducing the establishment of natural enemies and their impact. We tested whether phylogenetic isolation of oak hosts from neighbouring trees within a forest canopy reduces phytophagy. We found that an increase in phylogenetic isolation by 100 million years corresponded to a 10-fold decline in phytophagy. This was not due to poorer living conditions for phytophages on phylogenetically isolated oaks. Neither species diversity of neighbouring trees nor spatial distance to the closest oak affected phytophagy. We suggest that reduced pressure by natural enemies is a major advantage for individuals within a host species that leave their ancestral niche and grow among distantly related species.
    Kaolin particle films suppress many apple pests, disrupt natural enemies and promote woolly apple aphid
    Markó, V. ; Blommers, L.H.M. ; Bogya, S. ; Helsen, H.H.M. - \ 2008
    Journal of Applied Entomology 132 (2008)1. - ISSN 0931-2048 - p. 26 - 35.
    dysaphis-plantaginea - autumn kaolin - management - orchards - arthropod - homoptera - behavior - insecticides - lepidoptera - tortricidae
    Multiple applications of hydrophobic kaolin particle film in apple orchards suppressed numbers of blossom weevil (Anthonomus pomorum), brown leaf weevil (Phyllobius oblongus), attelabid weevil (Caenorhinus pauxillus), leafhoppers (Empoasca vitis and Zygina flammigera) and green apple aphid (Aphis pomi) colonies. The kaolin treatments reduced the apple sawfly (Hoplocampa testudinea) fruit infestation on cultivar J. Grieve, and the fruit damage caused by oyster scale (Quadraspidiotus ostreaeformis), mussel scale (Lepidosaphes ulmi), early caterpillars, leaf rolling moths (Tortricidae), fruitlet-mining tortrix moth (Pammene rhediella) and codling moth (Cydia pomonella). There was no effect on the number of colonies of rosy leaf curling aphid (Dysaphis devecta), nor on the fruit damage caused by common earwig (Forficula auricularia) and apple sawfly on cv. G. Delicious. The level of infestation of rosy apple aphid (Dysaphis plantaginea), leaf miner moths (Phyllonorycter blancardella, Lyonetia clerkella), and agromyzid flies (Phytomyza heringiana) increased in the kaolin-treated plots. Kaolin treatments promoted woolly apple aphid (Eriosoma lanigerum) infestation, which became severe, while it reduced the abundance of polyphagous predators like F. auricularia, predaceous Heteroptera and Coleoptera, the red velvet mite (Allothrombium fuliginosum), spiders (Araneae) and the abundance of common black ant (Lasius niger). The treatments also reduced parasitism of the apple sawfly by the ichneumonid Lathrolestes ensator. Many weeks after ending the kaolin treatments, the number of predaceous Coleoptera and especially the number of spiders remained low in the kaolin-treated plots.
    Beheersing van bladrollers in de boomkwekerij : bestrijding anjerbladroller en andere bladrollers
    Linden, A. van der - \ 2007
    Lisse : PPO Bloembollen en Bomen - 25
    tortricidae - boomteelt - plantenziektebestrijding - biologische bestrijding - sexferomonen - sierteelt - tortricidae - arboriculture - plant disease control - biological control - sex pheromones - ornamental horticulture
    In de boomkwekerij kan een groot aantal soorten bladrollers voorkomen op verscheidene gewassen. Een relatief nieuwe soort is de anjerbladroller, Cacoeocimorpha pronubana. Deze soort is de laatste jaren de dominante soort in de boomkwekerij. Voor veel soorten is het sexferomoon te koop zodat vallen met sexferomoon kunnen worden gebruikt om vast te stellen of die soort vliegt. Deze vallen vangen alleen mannetjes en zijn niet geschikt om bladrollers massaal weg te vangen. De toepassing van sexferomoon als verwarringstechniek, waarbij zeer hoge hoeveelheden feromoon in de lucht worden afgegeven, is al eerder onderzocht. Dat heeft echter nooit tot een praktische toepassing geleid.
    Onderzoek naar de mogelijke besmetting van een partij hooi met haren van de eikenprocessierups
    Spijker, J.H. ; Aelst, A.C. van; Niemeijer, C.M. - \ 2007
    Wageningen : Alterra (Alterra-rapport 1606) - 25
    hooi - voer - paardenvoeding - paarden - besmetting - insecten - thaumetopoea processionea - tortricidae - insectenplagen - bomen - voederveiligheid - hay - feeds - horse feeding - horses - contamination - insects - thaumetopoea processionea - tortricidae - insect pests - trees - feed safety
    Mogelijk effect van dierziekte bij paarden als gevolg van het voorkomen van restatnten van de eikenprocessierups in diervoeder, namelijk hooi
    Nieuwe mineermot op paardenkastanje; landelijke inventarisatie
    Moraal, L.G. - \ 2000
    Tuin en Landschap 22 (2000)15. - ISSN 0165-3350 - p. 38 - 40.
    insecten - insectenplagen - populatie-ecologie - groene zones - openbare parken - recreatiegebieden - publieke tuinen - oogstschade - diagnostische technieken - cameraria - bosbouw - nederland - stedelijke gebieden - tortricidae - aesculus hippocastanum - forestry - insects - cameraria - tortricidae - aesculus hippocastanum - insect pests - population ecology - green belts - public parks - amenity and recreation areas - public gardens - urban areas - crop damage - diagnostic techniques - netherlands
    Inventarisatie van schadelijke insecten op bomen en struiken in het stedelijk gebied en het landschappelijk groen met afbeeldingen van schadebeelden en een overzicht van de insecten top tien 1999
    De paardekastanjemineermot nieuw voor Nederland
    Moraal, L.G. - \ 2000
    Vakblad Natuurbeheer 39 (2000)7. - ISSN 1388-4875 - p. 111 - 113.
    cameraria - tortricidae - aesculus hippocastanum - bladmineerders - insecten - ecologie - epidemiologie - oogstschade - biologische bestrijding - nuttige insecten - nederland - cameraria - tortricidae - aesculus hippocastanum - leaf miners - insects - ecology - epidemiology - crop damage - biological control - beneficial insects - netherlands
    Levenswijze, schadebeeld, verspreiding en natuurlijke vijanden van de paardekastanjemineermot
    Eikenprocessierups op kop bij inventarisatie insectenplagen 1998
    Moraal, L.G. - \ 1999
    Tuin en Landschap 21 (1999)17. - ISSN 0165-3350 - p. 44 - 46.
    insecten - tortricidae - insectenplagen - bomen - groene zones - openbare parken - recreatiegebieden - publieke tuinen - thaumetopoea processionea - insects - tortricidae - insect pests - trees - green belts - public parks - amenity and recreation areas - public gardens - thaumetopoea processionea
    De insecten Top Tien 1998 in de groenvoorzieningssector: 1) De Eikenprocessierups, Thaumetopoea processionea, 2) Lindenbladwesp, Cariloa annulipes, 3) Wilgenhoutrups, Cossus cossus, 4) Koningsschildluis, Pulvinaria regalis, 5) Lepenspintkevers, Scolytus spp., 6) Elzenhaan, Yponomeuta spp., 7) Elzenhaan, Agelastica alni, 9) Meikever, Melolontha melolontha, 10) Rozenkever, Phyllopertha horticula
    The potential of natural enemies to suppress rice leaffolder populations
    Kraker, J. de - \ 1996
    Agricultural University. Promotor(en): J.C. van Lenteren; R. Rabbinge; A. van Huis. - S.l. : De Kraker - ISBN 9789054856016 - 257
    insecten - insectenplagen - tortricidae - rijst - oryza sativa - gastheer parasiet relaties - parasitisme - gewasbescherming - biologische bestrijding - cnaphalocrocis medinalis - marasmia - microlepidoptera - insects - insect pests - tortricidae - rice - oryza sativa - host parasite relationships - parasitism - plant protection - biological control - cnaphalocrocis medinalis - marasmia - microlepidoptera

    Rice leaffolders Cnaphalocrocis medinalis and Marasmia spp. (Lepidoptera: Pyralidae) are considered major pests in many Asian countries. Insecticide use against leaffolders is wide-spread, but may not be justified due to tolerance of the rice crop to leaffolder injury and a high level of natural biological control. This study was conducted to obtain more insight in the potential of indigenous natural enemies to suppress rice leaffolder populations and reduce the damage inflicted to the crop. The study started with a descriptive analysis of leaffolder population dynamics in Philippine rice fields, and then concentrated on experimental analysis of egg mortality and the impact of individual predator species. Models were used to integrate the experimental findings, to explain field observations, and to explore the consequences of varying biotic and abiotic conditions for leaffolder population dynamics and damage.

    Rice leaffolder populations in eight unsprayed rice crops were characterized by an egg peak at maximum tillering and a broad larval peak around the booting stage, with peak larval densities ranging from 0.2 to 2.0 per hill. Variation in survival from egg to larval stages between crops was not correlated with the level of egg parasitism, natural enemy abundance, or predator-prey ratios. High levels of N-fertilization resulted in a strong increase in leaffolder larval density and injury, due to a positive effect on egg recruitment and survival of medium-sized larvae. The increase in larval survival was associated with lower predator-prey ratios. Egg mortality in the field a veraged about 60%, and was mainly due to disappearance of eggs and to a lesser extent to parasitism by Trichogramma spp. Non-hatching was of minor importance. The level of egg disappearance was positively correlated with the densities of the predatory crickets Metioche vittaticollis and Anaxipha longipennis. Direct observations confirmed the major role of these crickets: in two crop seasons they were responsible for more than 90% of the observed egg predation. Minor predators were Micraspis sp., Ophionea nigrofasciata, and Conocephalus longipennis. The egg predation rate of the crickets in cages was described adequately with a linear functional response model, indicating that predation was limited only by the search rate. Increasing the predator density per cage led to a decrease in the egg predation rate per capita. Field testing of a model of predation of leaffolder eggs based on cage experiments showed that the observed trend in egg predation could be described as a function of cricket densities and crop leaf area. The evaluation also indicated that predator interference may limit the egg predation rate of the crickets, while the presence of alternative prey did not. A simulation study with a combined model of leaffolder population dynamics and rice crop growth highlighted the importance of natural enemies as well as crop growing conditions. The simulations indicated that larval densities as observed in the unsprayed fields would not cause significant yield loss in a wellfertilized crop. Yield losses simulated with an average leaffolder immigration pattern exceeded economic damage levels when no natural enemy action was included, while introduction of three field-observed natural mortality factors (egg predation, egg and larval parasitism) reduced losses to below these levels. Over their observed range in seasonal abundance, the predatory crickets could reduce leaffolder damage by 5 to 60% (average: 35%).

    The identification of the major egg predators and quantification of their impact can serve as a starting point for research on strategies to conserve natural enemies of rice leaffolders, and as inputs to IPM training programs to stimulate farmers to reduce insecticide sprays against rice leaffolder. The study also indicated the importance of optimization of nitrogen fertilization to avoid reliance on chemical control, by maximizing the positive effects on yield formation and tolerance to injury, while minimizing the leaffolder density response. For this purpose, a combined leaffolder-rice simulation model is a useful, integrative tool, to study how interaction between these mechanisms affects rice yield.

    Analysis of the sex pheromones of Symmetrischema tangolias and Scrobipalpuloides absoluta
    Griepink, F.C. - \ 1996
    Agricultural University. Promotor(en): Æ. de Groot; J.H. Visser; T.A. van Beek. - S.l. : Griepink - ISBN 9789054855736 - 132
    feromonen - tortricidae - insecten - plantenplagen - analyse - chemie - microlepidoptera - analytische scheikunde - pheromones - tortricidae - insects - plant pests - analysis - chemistry - microlepidoptera - analytical chemistry

    Sex pheromones are substances which are used by insects to attract a partner with the intention to mate. Pheromones are essential for the species survival because without them the partner cannot be located. When the chemical structures are known, the sex pheromones could be applied for pest control of that species. Sex pheromones are produced by the insect itself and they are attractive in very low concentrations. The development of resistance against sex pheromones, in contrast to pesticides, is considered unlikely. Owing to the species specificity and the low amounts necessary, the natural environment of the pest is less afflicted by the use of sex pheromones in comparison to conventional pesticides.

    This thesis describes the isolation, identification and possible applications of the sex pheromones of two South-American moths, Symmetrischema tangolias and Scrobipalpuloides absoluta . The research was carried out as a co-operative project between the Research Institute for Plant Protection (IPO-DLO), Wageningen, The Netherlands, the Department of Organic Chemistry of the Wageningen Agricultural University (OC-WAU) and the International Potato Center, Lima, Peru (CIP). The project was financially supported by the Netherlands' Minister for Development Co-operation.

    The moth Symmetrischema tangolias (Gyen), synonym: Symmetrischema plaesiosema (Turner), occurs mainly in the higher regions of the Andes in Peru and Bolivia where it is a severe pest of potatoes. The larva lives in the fields in the stems of potato plants and in storage places in the tubers. The harvested potatoes are stored in open facilities which are easy accessible to the insects. The potato growing is essential for the local food provision in the above-mentioned areas.

    The sex pheromone of Symmetrischema tangolias has been identified (chapter 3) as a 2: 1 mixture of (E,Z)-3,7-tetradecadienyl acetate ( 6 ) and (E)-3-tetradecenyl acetate ( 1 ). In the sex pheromone glands, two additional minor, to the sex pheromone related, compounds have been identified, namely (Z)-5-tetradecenyl acetate (25) and (Z)-7-tetradecenyl acetate ( 26 ) (figure 8.1). The ratio of these compounds in the sex pheromone gland is: 63 : 31 : 5 : 1 for 6 : 1 : 26 and 25 respectively.

    In a new wind tunnel at IPO-DLO, several mixtures of the identified and synthesised sex pheromone components have been tested in different ratios (chapter 6). A mixture of 6 and 1 appears to be more attractive than the two components separately. Mixtures of 6 and 1 in ratios of 1 : 1 and 2: 1 are equally attractive. The addition of small amounts of minor components 25 and 26 does not affect the attractiveness of the sex pheromone blend. The function of these two minor components therefore remains unclear.

    The amounts and ratios of the four gland constituents were measured during the 24-hrs dark- light cycle (chapter 4). A new approach was followed which involved the direct introduction of sex pheromone glands into the gas chromatograph (GQ by using a special temperature programmable GC-injector. With this method it was possible to examine glands without prior processing which provides a clear advantage over earlier described methods. It turns out that the total amount of sex pheromone in the glands varied strongly from individual to individual (3.8 - 350 ng/♀). The total sex pheromone amounts were significantly lower in the scotophase than in the photophase (62.2 and 101.5 ng/♀respectively). The ratios of the various gland constituents showed a symmetrical distribution which did not fluctuate during the 24-hrs dark-light cycle.

    The synthetic sex pheromone was highly attractive to male Symmetrischema tangolias in field tests conducted in potato fields and in storage facilities in Peru. The local farmers were exited about the results and wish to apply the sex pheromone as soon as it becomes available. Although the synthesis of the mono-unsaturated compound 1 is easy, large scale synthesis of the double-unsaturated compound 6 (which has been never reported before) is problematic.

    The moth Scrobipalpuloides absoluta (Meyrick), synonym: Scrobipalpula absoluta (Meyrick), lives in low altitude areas of South America. The larva is a leafminer of tomatoes and has developed into a devastating pest in tomato cultivation, especially in Brazil, Peru and Chile. In contrast to small-scale potato crops in higher parts of the Andes, the tomato growing is a large-scale and professional business. The harvested tomatoes are largely processed and exported. Therefore, tomato growing is of national economic interest for the involved countries.

    The sex pheromone of Scrobipalpuloides absoluta has been identified (chapter 5) as a 9: 1 mixture of (E,Z,Z)-3,8,11-tetradecatrienyl acetate ( 16 ) and (E,Z)-3,8- tetradecadienyl acetate ( 3 ) respectively (figure 8.2).

    The ratio of these two identified compounds in the sex pheromone gland is 92: 8 (for 16 : 3 respectively). On a Peruvian tomato farm, several mixtures of the identified compound were tested in ratios between 100 : 0 and 80 : 20, for 16 : 3 respectively. All tested mixtures turned out to be highly attractive to Scrobipalpuloides absoluta males, however, none of them appeared superior. Both the identified sex pheromone components 16 and 3 are unique to this species. The synthesis of the minor compound 3 can be increased easily, however, large-scale synthesis of 16 may provide more problems due to its three double bonds.

    Various techniques were used to identify the sex pheromones of Symmetrischema tangolias and Scrobipalpuloides absoluta. By means of GC, the chain lengths, functional groups and number of double bonds could be established. The active components were found in the gas chromatogram by means of electroantennography (EAG-detector). This detection technique is based on the application of the insect's antenna (olfactory organ) as a detector. From the gas chromatographical research it turned out that the sex pheromone candidates for both species belonged to the same group of linear unsaturated compounds all with a chain length of 14 carbons. The mono-unsaturated components 1 , 25 and 26 could be identified with related reference compounds which were all available at IPO-DLO. Of the double-unsaturated compound 6 of the Symmetrischema tangolias sex pheromone sufficient amounts could be isolated by means of preparative GC to unambiguously determine the (E)-3-double bond with NMR. Through EAG-recordings of all mono-unsaturated related compounds the (Z)-7-double bond was postulated as the other double bond in molecule 6 . The synthesis of 6 confirmed the postulated structure. By means of derivatisation of sex pheromone compounds with dimethyl disulphide (DMDS) subsequently followed by analysis of the derivatives obtained with mass spectrometry, the double bond positions in the mono- and double-unsaturated compounds could be determined directly. For compound 3 the two double bonds could be located at positions 3 and 8 with the DMDS method. All four possible (E/Z) isomers were synthesised, tested with EAG-recordings and compared to the analytical obtained data on the minor sex pheromone component of Scrobipalpuloides absoluta. Through this the identity of 3 could be confirmed. With the DMDS derivatisation technique two of the three double bonds in 16 could be unambiguously located at positions 3 and 8, similar to the minor component 3 . The obtained EAG results suggested the same E/Z configuration for these two double bond positions in 16 . GC-analysis of available mono- and polyunsaturated related compounds left three possibilities for the structure of 16 . The identity of 16 was determined through synthesis of all three possibilities and comparison of the analytical data with the data obtained for the sex pheromone compound.

    A closer investigation of the DMDS derivatives of these latter three triple-unsaturated compounds revealed the possibility for the direct determination of all three double bond positions solely through interpretation of mass spectra. This has not been reported before for these types of molecules. For this reason, and because of its importance for this kind of research, a separate chapter (chapter 2) was dedicated to it.

    The discussion contains a proposal for the biosynthetic formation of the identified sex pheromones. Also the price control in commercial synthesis of sex pheromones is mentioned and illustrated through an example. Both pheromones of Symmetrischema tangolias and Scrobipalpuloides absoluta contain a synthetically problematic compound. Considering the need for these sex pheromones it is recommended to continue the research for more efficient synthetic routes.

    Onderzoek naar de verspreiding van de anjerbladroller, Cacoecimorpha pronubana (Huebner), in Nederland, vooral in het Zuidwesten, gedurende 1994
    Woets, J. - \ 1995
    Wilhelminadorp : Proefstation voor de Fruitteelt
    insecten - plantenplagen - tortricidae - tuinbouw - plantenziekten - epidemiologie - distributie - nederland - microlepidoptera - insects - plant pests - tortricidae - horticulture - plant diseases - epidemiology - distribution - netherlands - microlepidoptera
    De kleine vlinders : Handboek voor de faunistiek van de Nederlandse Microlepidoptera
    Kuchlein, J.H. ; Donner, J.H. - \ 1993
    Wageningen : Pudoc - 715
    dieren - zoögeografie - fauna - handboeken - identificatie - lepidoptera - nederland - tortricidae - wildbescherming - microlepidoptera - animals - zoogeography - fauna - handbooks - identification - lepidoptera - netherlands - tortricidae - wildlife conservation - microlepidoptera
    Parasites of Lepidopteran stemborers of tropical gramineous plants.
    Jr. Smith, J.W. ; Wiedenmann, R.N. ; Overholt, W.A. - \ 1993
    Nairobi : ICIPE Science Press - ISBN 9789290640561 - 89
    nuttige insecten - biologische bestrijding - graansoorten - voedselgewassen - insecten - noctuidae - insectenplagen - tortricidae - tropen - stengelboorders - microlepidoptera - stem borers - beneficial insects - biological control - cereals - food crops - insects - noctuidae - insect pests - tortricidae - tropics - microlepidoptera
    Integrated pest management in apple orchards in the Netherlands : a solution for selective control of tortricids
    Reede, R.H. de - \ 1985
    Landbouwhogeschool Wageningen. Promotor(en): J.C. van Lenteren, co-promotor(en): L.H.M. Blommers. - Wageningen : De Reede - 103
    appels - biologische bestrijding - insecten - malus - nederland - plantenplagen - gewasbescherming - tortricidae - microlepidoptera - apples - biological control - insects - malus - netherlands - plant pests - plant protection - tortricidae - microlepidoptera
    Field trials to compose a coherent system of Integrated Pest Management (IPM) for apple orchards in the Netherlands were started in 1967, when the 12 ha apple orchard "De Schuilenburg" at Kesteren became available for experiments on IPM. Natural control of one of the most severe pests under conventional control, the fruit tree red spider mite Panonychus ulmi , is a central part in IPM. Many broad-spectrum pesticides exterminate the predacious mite Typhlodromus pyri , which is responsible for the natural control in IPM in the Netherlands. Only selective agents are applied, therefore, against pests which are not, or only partially, naturally controlled, preserving T. pyri and other useful arthropods.

    The aim of the present study was to investigate the feasibility of the following selective compounds for leafroller control in IPM in apple orchards: (a) a bacterial agent, Bacillus thuringiensis (Dipel), (b) a chitine synthesis inhibitor, diflubenzuron (Dimilin) and (c) insect growth regulators (IGR) with juvenile-hormone activity, epofenonane and fenoxycarb.

    Initial studies were carried out at the experimental orchard "De Schuilenburg", in 0.5-1.0 ha plots, for five consecutive years. The degree of leafroller fruit damage in untreated plots ranged from 5 to 13%; this damage was caused by a complex of leafroller species. Adoxophyes orana was most abundant in the summer, whereas Spilonota ocellana , Pandemis heparana and Hedya nubiferana were dominant in the spring. Under Dipel regimes, both the total leafroller population and the leafroller fruit injury were halved. Dipel was relatively ineffective against P.heparana, H. nubiferana and, in particular, S. ocellana . Dimilin also halved leafroller fruit injury. This compound was very effective against S. ocellana , H. nubiferana and Archips podana . Dimilin, however, did not affect A. orana and the population of P. heparana was only reduced to about one-third of the blanco value. Leafroller control with epofenonane, which was applied twice in the spring, was not succesful. This may be due to reinfestation from the untreated plots, which lay adjacent to the treated plots in our experimental set- up. Dipel, Dimilin and epofenonane did not appear to affect the level of parasitism of A. orana by Colpoclypeus florus . However, in this respect the standard plots, treated with broad-spectrum insecticides, gave similar results, so no firm conclusion can be drawn.

    A second series of experiments concerned the effect of fenoxycarb and epofenonane. Apple trees were either artificially infested with A. orana and P. heparana or harboured several naturally occurring leafroller species. The caterpillars were restricted in gauze-bags on leaf-clusters after the apple trees had been sprayed once or twice, and the morphogenetic effect was observed. Fenoxycarb was effective at a concentration about 10 times lower than that of epofenonane. The foliar residue of fenoxycarb remained active for at least 4 weeks. Laboratory experiments indicated that although the foliar residue of epofenonane caused severe morphogenetic effects on the host A. orana, the ectoparasite Colpoclypeus florus completed its development on the host. When the host and parasite were exposed to fenoxycarb, however, the parasite often died at the pupal stage. Similar experiments with the endoparasite Apanteles ater in the host Archips rosana did not reveal higher mortality of the parasite than in the control.

    In a following study, large-scale application of fenoxycarb and epofenonane in various IPM apple orchards were tested for several consecutive years. The IPM orchards were carefully selected to include IPM orchards adjacent to conventionally sprayed orchards, and IPM orchards well isolated from other orchards. The population of the leafroller species as well as the leafroller fruit injury level could be kept low by spraying twice in spring, irrespective of the location of the orchard. Reinfestation from adjacent orchards, if it occurred at all, played only a minor role in the final effect.

    The determination of the timing of epofenonane and fenoxycarb required sampling of larvae and periodical observations on the larval stage. In order to facilitate the timing simulation models were developed to predict the emergence of the last instar of P.heparana and A. orana in the field. These models were based on laboratory experiments and on data from the literature and included only the temperature as a driving variable. The simulated curves of emergence of last-instar larvae, pupae and adults corresponded well with the field observations. To investigate whether the time of IGR application could be related to a temperature sum, the relation between emergence curves of last-instar larvae and temperature sum was studied for several years. For this purpose simulated curves were used, because field-observations on emergence of last-instar larvae covered only two years. Using the established relation between temperature sum and developmental stage of the leafroller population, only temperature sums need to be calculated for the timing of applications of IGR's.

    The isolating effect of greenhouses on arthropod pests [and its significance for integrated pest management] : a case-study on Clepsis spectrana (Lepidoptera: Tortricidae)
    Bos, J. van den - \ 1983
    Landbouwhogeschool Wageningen. Promotor(en): J. de Wilde, co-promotor(en): G.W. Ankersmit. - Wageningen : van den Bos - ISBN 9789022008393 - 93
    tortricidae - insecten - plantenplagen - gewasbescherming - biologische bestrijding - adaptatie - acclimatisatie - milieu - seizoenen - fotoperiode - fotoperiodiciteit - nuttige insecten - clepsis spectrana - microlepidoptera - schadelijke dieren - tortricidae - insects - plant pests - plant protection - biological control - adaptation - acclimatization - environment - seasons - photoperiod - photoperiodism - beneficial insects - clepsis spectrana - microlepidoptera - noxious animals
    Chapter 1: the environmental conditions in greenhouses differ in many respects from those in the open field. Both the climate and the crops are different. A free exchange between the fauna of the greenhouses and the open air is hampered by the glass walls and roofs. The isolating effect of greenhouses on arthropod pests contributes to the effectiveness of control measures, but also to the development and maintenance of pesticide resistance in greenhouses. Because of the special conditions a specific fauna exists in greenhouses, and the use of exotic predators and parasites for biological control is possible. The greenhouse environment acts as a "sieve" only allowing such species to thrive that are adapted to these special conditions. These are sometimes exotic species that cannot thrive in the open in the Dutch climate. Native species may penetrate into greenhouse cultures, but to pass the "sieve" they have to adapt to greenhouse conditions.

    The leaf-roller Clepsis spectrana Tr. is native in the Netherlands. It gives an example of the development of a greenhouse-adapted biotype. In Dutch greenhouses, especially on roses, it causes much damage. In heated greenhouses, where artificial illumination is not given, growth and reproduction of C. spectrana continue without diapause during winter, which is advantageous for the species in this environment, where the difference between summer and winter temperatures does not exceed a few degrees and suitable food is available all the year round.

    Chapter 2 deals with the morphology, bionomics, host plant range, and distribution area of C. spectrana. Chapter 3 describes the materials and methods.

    Chapter 4: the number of larval instars from egg hatching to pupation varied between 4 and 8 in both field and greenhouse strains. Each larval growth type had its own specific progression of head capsule width. The difference in head capsule width between the 4- and 5-instar type was already evident in the 1st instar, between the Sand 6-instar type in the 2nd instar, and between the 6- and 7-instar type only in the 3rd instar or even later. Females tended to develop through a higher number of instars than males, but 5 instars was the most usual in both sexes. The development duration was the same in field and greenhouse strains, in each of the immature stages. The upper thermal limit for development was between 30 °C and 35 °C in both field and greenhouse strains, whereas the developmental threshold was close to 10 °C. An adaptation of greenhouse populations of C. spectrana to development at higher temperatures did not appear.

    Chapter 5: short daylength induced diapause in field strains in the larval stage. The critical photoperiod was between 16 and 17 hours. The number of moults up to the onset of diapause varied between 2 and 6, and was determined by the photoperiod. Larvae from eggs hatching later in the season entered diapause after a lower number of moults. The time of resumption of growth after diapause termination in spring was not correlated with the date of egg hatching in the previous year, in outdoor experiments. The larvae underwent supernumerary moults after termination of diapause. The duration of post-diapause development was longer as diapause had been entered after less moults. The number of moults after termination of diapause, and the duration of post-diapause development, were sex-linked. The functional significance of these phenomena is discussed.

    Chapter 6: the photoperiodic response of 5 different greenhouse strains, originating from larvae and pupae collected in different rose houses at different times of the year (both in summer and in winter), was tested in the laboratory. These greenhouse strains did not enter diapause, at both 20 °C and 15 °C, regardless of the photoperiod, One greenhouse strain was also reared outdoors. Egg hatching dates were August 1, August 17, September 25, and October 14. At least the major part of the larvae did not enter diapause.

    Chapter 7: field strain larvae entered diapause in a heated greenhouse, but the absence of a period of chilling caused an abnormal growth pattern in these larvae, compared to larvae terminating their diapause outdoors: (a) larval development duration was extremely variable (larvae from field strain eggs that hatched at August 24 in the greenhouse, pupated between January 28 and July 15 of the following year), (b) The difference in mean developmental time between male and female larvae was greatly increased, and (c) the mean number of moults, and the variation in the number of moults, Were increased. The survival of diapausing larvae, however, was not essentially affected by the absence of a period of chilling. The time required for diapausing larvae to reach the pupal stage under conditions without a cold period, was genetically determined, and could be shortened rapidly by selection.

    Chapter 8: a difference in the composition of the female sex pheromone between field and greenhouse strains could not be shown, nor in the calling behaviour of virgin females in relation to the light-dark cycle. Release-recapture trials revealed that females of both strains attracted males of both strains in equal proportions. There did not appear to be a difference in mating preference.

    Chapter 9: the index of genetic identity (I) of a field population on stinging nettles from the middle of the country, and a rose house population from the West of the country, amounted to 0.994 (based on allozyme frequencies). This is the level for panmictic populations of one species. Field and greenhouse strains could readily be intercrossed, with a viable F2 generation.

    Chapter 10: field and greenhouse populations of C. spectrana are certainly still conspecific. It is adequate to speak of a "field biotype" and a "greenhouse biotype". The greenhouse biotype is characterised by absence of the ability to enter diapause. When the biotypes are brought together, hybridization and introgression certainly will occur. Immigration of the field biotype into heated greenhouses apparently is sufficiently low to maintain a separate greenhouse biotype with constant characteristics. The origin of the greenhouse biotype might be a non-diapausing geographic race of C. Spectrana, from the warmest parts of its distribution area, or the field biotype immigrated into heated greenhouses, and subsequently lost its ability to enter diapause. The last possibility seems the most likely.

    Chapter 11: pheromonal trapping of C. spectrana is less effective in greenhouses than in the open air. Probably the specific nature of the air movements in greenhouses reduces the effectiveness of the long- range pheromone-mediated behaviour of the males. However, male pheromone-mediated behaviour in short-range orientation, close to calling females, may be unaffected (chapter 8.3). This decreases the effect of synthetic pheromone used for monitoring and mass trapping. However, application of the communication disruption technique may be successful under glass, because the overall concentration of synthetic pheromone in the air can be made much higher in greenhouses than in the open field. Further research is recommended.

    Controlling C. spectrana in greenhouses by releasing sterile males seems feasible, as: (a) immigration of new adults from outside almost certainly is negligible, and (b) C.spectrana is the only tortricid occurring in the Dutch floriculture; the danger that other leaf-rollers will take over when chemical control of C. spectrana ceases seems therefore small.

    Diapause can be crossed into greenhouse populations of C. spectrana by releasing males of the field biotype. This probably is an ineffective way of controlling these populations.

    Parasitised C. spectrana larvae were found in several greenhouses, even in winter. The parasites, which were not identified, apparently were not diapausing. It is recommended to make a survey of the parasite fauna of C. spectrana in greenhouse cultures.

    Bladrollers in appel- en pereboomgaarden
    Jong, D.J. de; Beeke, H. - \ 1982
    Wilhelminadorp : Proefstation voor de Fruitteelt (Mededeling / Proefstation voor de Fruitteelt no. 19) - 218
    insecten - insectenplagen - appels - peren - tortricidae - microlepidoptera - insects - insect pests - apples - pears - tortricidae - microlepidoptera
    Maatregelen ter preventie van Adoxophyes orana (F.v.R.) plagen
    Anonymous, - \ 1979
    Wageningen : Pudoc (Literatuurlijst / Centrum voor landbouwpublikaties en landbouwdocumentatie no. 4221)
    appels - bibliografieën - vruchtbomen - insecten - malus - boomgaarden - plantenplagen - tortricidae - microlepidoptera - apples - bibliographies - fruit trees - insects - malus - orchards - plant pests - tortricidae - microlepidoptera
    Characterization of nuclear polyhedrosis viruses obtained from Adoxophyes orana and from Barathra brassicae
    Jurkovicova, M. - \ 1979
    Landbouwhogeschool Wageningen. Promotor(en): J.P.H. van der Want, co-promotor(en): D. Peters. - Wageningen : Jurkovicova - 133
    baculovirus - biologische bestrijding - organismen ingezet bij biologische bestrijding - insecten - lepidoptera - noctuidae - kernpolyedervirussen - plantenplagen - tortricidae - virusmorfologie - virologie - virussen - adoxophyes orana - mamestra brassicae - microlepidoptera - baculovirus - biological control - biological control agents - insects - lepidoptera - noctuidae - nuclear polyhedrosis viruses - plant pests - tortricidae - viral morphology - virology - viruses - adoxophyes orana - mamestra brassicae - microlepidoptera
    ln infectivity experiments some A. orana larvae died after being inoculated with an inoculum containing NW isolated from B. brassicae. The polyhedra formed upon infection occluded single virus particles, whereas the inoculum contained polyhedra with bundles of virus particles. This change could be explained either by activation of a virus in A. orana, which is singly embedded, or the inoculum from B. brassicae had infected A. orana and consequently the inclusion of virus particles in outer membranes is controlled by the hosts. This thesis describes studies performed to discriminate between both possibilities. Therefore, the first task was to characterize the virus particles from B. brassicae and A. orana NPV and their polyhedra by different techniques (Chapter 1).

    The properties of the NW of A. orana and of B. brassicae as observed with the electron microscope and polyacrylamide gel electrophoresis are similar to those found for many other NPVs. The polyhedra of both NPVs differ in size and shape. Most of the A. orana polyhedra are globular and range in diameter from 1-2 μm. Most of the B. brassicae polyhedra are hexagonal or pentagonal in outline and range in diameter from 1.5-4 μm. Analysis of polyhedral protein by polyacrylamide gel electrophoresis shows the presence of two polypeptides of molecular weight 28,000 and 54,000 Daltons.

    Treatment of the polyhedra of both viruses with sodium carbonate ruptures the polyhedral membrane and the virus particles and polyhedral proteins are released. The virus particles of A. orana polyhedra are singly embedded in the polyhedral matrix and have a size of 250 x 60 nm. The multiply embedded virus particles of B. brassicae have a size of 347 x 113 nm. Analysis of the viral proteins by SDS-polyacrylamide gel electrophoresis showed that NW of A. orana has 5 polypeptides of 68,000, 48,000, 39,000, 32-34,000, and 28,000 Daltons, respectively. Those of the NPV of B. brassicae were 69,000, 57,000, 46,000, 34-39,000, and 28,000 Daltons, respectively.

    In the polyhedral membrane fractions of both polyhedra one polypeptide of molecular weight of 28,000 Daltons as estimated by polyacrylamide gel electrophoresis, was found.

    Due to proteolytic activity associated with the polyhedra, which is evident after dissociation of the polyhedra, it was difficult to establish the number of polyhedral proteins and their molecular weight (Chapter 2). The electrophoretic pattern of polyhedral proteins of A.orana and B. brassicae polyhedra dissociated in alkali differed from those proteins obtained by other means. Six to seven polypeptides with molecular weights between 28,000 and 8,000 Daltons were found after incubation at pH 10.5. After inactivation of the enzyme only two polypeptides with molecular weights of 28,000 and 26,000 Daltons were observed. When the polyhedral proteins were analysed without incubation at pH 10.5 also two proteins were found, but their molecular weight was 54,000 and 28,000 Daltons.

    On the basis of the results described in Chapters 1 and 2 it can be concluded that the virus particles of B. brassicae and A.orana NPV differ with respect to size, the way of occlusion, and the form and size of the polyhedra involved. Protein analysis by polyacrylamide gel electrophoresis reveal some difference in molecular weight of viral protein but no significant difference in the protein composition of their polyhedra. Further analyses of amino acid composition and sequence of these proteins is necessary to elucidate possible differences.

    To differentiate further between both viruses their genomes were analysed (Chapter 3). Both genomes are circular double-stranded DNA molecules. The molecular weights of A.orana and of B. brassicae NPV-DNAs are 6.7 x 10 7and 8.9 x 10 7Daltons, respectively as determined by electron microscopy and by renaturation kinetic analysis. The renaturation also indicated that both genomes contain only unique sequences. The buoyant density in CsCl of the NPV-DNA of A. orana and of B. brassicae is 1.694 and 1.696 g/cm 3, respectively. These values are in good agreement with (G+C) contents of 34.5 and 37%, respectively as determined by thermal denaturation. The digestion of the A. orana and of the B. brassicae NPV-DNA with endonuclease Eco RI resulted in completely different electrophoretic patterns. Also in experiments on
    competition hybridization no homology between these genomes was found. The conclusion of these studies is that these two NPVs can be clearly differen tiated by their DNA properties.

    In order to study the occurrence of viral DNA in uninfected larvae the DNA of A. orana and B. brassicae was isolated and the complexity studied (Chapter 4). The genomes of A.orana and of B. brassicae differ in their kinetic complexity as estimated from the reassociation data on hyperchromicity, but they are both relatively small and show remarkable similarity in the extent of intragenome homology. A haploid cell of A. orana has a DNA equivalent of 4.2 x 10 10and that of B. brassicae of 8.4 x 10 10Daltons. The intragenome homology was estimated to be 10 and 9% for A.orana and B. brassicae genome, respectively. The (G+C) content, estimated by thermal denaturation, was found to be 36.2% for the A. orana genome and 35.8% for the B. brassicae genome.

    The results obtained during rearing of insects from surface-sterilized eggs and from untreated eggs showed that the NPV of A.orana and of B. brassicae can be transmitted to the progeny of these insects on the outside of the eggs (transovum) as well as inside the eggs (transovarially) (Chapter 5). Evidence for transovarial transmission was also obtained from reassociation of viral DNA with the host DNA of homologous insects reared from surface-sterilized eggs. These experiments revealed the presence of viral sequences in host DNA: 0.03 and about 2.5 viral copies for the diploid quantity of the A. orana and of the B. brassicae host DNA, respectively.

    Results obtained in infectivity experiments with insects in various developmental stages showed that transstadial transmission is a prerequisite for generation-to-generation transmission.

    The presence of a latent virus infection in both insects could also be demonstrated in cross-inoculation experiments (Chapter 6). When the larvae of A. orana and of B. brassicae were inoculated with polyhedra of the reciprocal species, the number of larvae containing polyhedra increased compared with that of the control. Comparison of the restriction endonuclease Eco RI pattern of DNA isolated from polyhedra used as inocula with that from polyhedra obtained after cross-inoculation indicated that both viruses are not cross-infective but that they activate a latent virus infection in both insects. Because the cross- inoculation experiments were done under laboratory conditions (as aseptic as possible), it could be concluded that the B. brassicae NPV is not suitable for biological control of A. orana in the field, because this virus is not cross-infective.

    Platyptilia gonodactyla en andere soorten Platyptilia
    Anonymous, - \ 1977
    Wageningen : Pudoc (Literatuurlijst / Centrum voor landbouwpublikaties en landbouwdocumentatie no. 4058)
    bibliografieën - insecten - plantenplagen - tortricidae - microlepidoptera - bibliographies - insects - plant pests - tortricidae - microlepidoptera
    Simulation of the fluctuations of the grey larch bud moth
    Bos, J. van den; Rabbinge, R. - \ 1976
    Wageningen : Pudoc (Simulation monographs ) - ISBN 9789022005897
    tortricidae - populatiedynamica - bosbouw - bomen - dieren - populatiedichtheid - populatie-ecologie - mortaliteit - populatiegroei - computersimulatie - simulatie - simulatiemodellen - zwitserland - bosschade - insecten - insectenplagen - larix decidua - microlepidoptera - tortricidae - population dynamics - forestry - trees - animals - population density - population ecology - mortality - population growth - computer simulation - simulation - simulation models - switzerland - forest damage - insects - insect pests - larix decidua - microlepidoptera
    Contributions to an integrated control programme of Hypsipyla grandella (Zeller) in Costa Rica
    Grijpma, P. - \ 1974
    Landbouwhogeschool Wageningen. Promotor(en): J. de Wilde, co-promotor(en): L.M. Schoonhoven. - Wageningen : [s.n.] - 147
    biogeografie - bestrijdingsmethoden - costa rica - ziektebestrijding - ecologie - bosschade - hydrobiologie - insectenplagen - insecten - geïntegreerde bestrijding - geïntegreerde plagenbestrijding - lepidoptera - plagenbestrijding - plantenziekten - plantenplagen - gewasbescherming - tortricidae - hypsipyla grandella - microlepidoptera - biogeography - control methods - costa rica - disease control - ecology - forest damage - hydrobiology - insect pests - insects - integrated control - integrated pest management - lepidoptera - pest control - plant diseases - plant pests - plant protection - tortricidae - hypsipyla grandella - microlepidoptera
    The shootborer Hypsipylagrandella (Zeller) (Lep., Pyralidae) is the main obstacle to the artificial regeneration of valuable meliaceous tree species such as mahogany ( Swietenia spp.) and Spanish cedar ( Cedrela spp.) in Latin America. On the other hand, the natural regeneration of these species is endangered due to depletion of the naturally existing resources and burning in colonization projects.

    This dissertation concerns the development of several fields of research, which when incorporated in a programme of integrated control may contribute to a solution of the Hypsipyla problem.

    Chapter 1 contains a general introduction on this insect pest and its host plants in Costa Rica. In addition, a review is provided of the economic importance of the pest in tropical forestry and of the previous and contemporary investigations on the possibilities of its control.

    The research carried out in the framework of the Inter-American Working Group on Hypsipyla at the tropical Research and Training Centre of the Inter-American Institute of Agricultural Sciences at Turrialba, Costa Rica, is dealt with in Chapter 2.

    These investigations refer to the natural resistance of Meliaceae, host selection, development of an artificial rearing technique for H . grandella and to a survey of parasites in Costa Rica which might be employed in a biological control of the shootborer.

    The main results are:

    a. Two exotic Meliaceae, African mahogany ( Khayaivorensis ) and the Australian cedar ( Toonaciliatavaraustralis ) were introduced and were found to be immune against attacks of the shootborer. Biological and chemical screening for the basis of resistance of the Australian cedar led to the location of two toxic components in the aqueous fraction of young leaves and shoots of this tree species. The toxicity of Toona can be translocated to Cedrelaodorata grafted on the Australian cedar.

    b. Experiments on the host selection of H . grandella point at the existence of a host selection mechanism in which the female adult orients itself towards the host by means of olfaction. Fourth instar larvae of the borer prefer native hosts to exotic species as food sources.

    c. An artificial rearing technique was developed for H . grandella . A diet (Vanderzant) used for rearing Heliothiszea appeared to be a suitable medium for mass rearing Hypsipyla . Although initially mating of adults could only be obtained in outdoor cages in Costa Rica, subsequent rearing in Wageningen, under completely artificial conditions, proved to be perfectly feasible. Larval and pupal periods of H . grandella reared on artificial and natural diets were determined, and compared. Female adults are generally larger than males and live longer. Artificially reared females still restrict oviposition to meliaceous host plants.

    d. A survey of biological control agents of -the shootborer resulted in the following new records of H . grandella parasites in Costa Rica: Trichogramma f asciatum , T . pretiosum , T . near pretiosum , T . semifumatum , Hypomicrogasterhypsipylae sp. n., Brachymeriaconica and Braconchontalensis ; an Agathis sp. has to be identified yet. In addition the nematode Hexamermisalbicans was found to parasitize larvae of the shootborer in Swieteniamacrophylla and Cedrela spp. The egg parasite Trichogrammasemifumatum could be reared easily on eggs of H . grandella .

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