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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Tussenevaluatie van de nota ‘Gezonde Groei, Duurzame Oogst’ : deelproject Milieu
Verschoor, A. ; Zwartkruis, J. ; Hoogsteen, M. ; Scheepmaker, J. ; Jong, F. de; Knaap, Y. van der; Leendertse, P. ; Boeke, S. ; Vijftigschild, R. ; Kruijne, R. ; Tamis, W. - \ 2019
Den Haag : Planbureau voor de Leefomgeving (RIVM rapport 2019-0044) - 167
Efficacy of plant extracts against the cowpea beetle, Callosobruchus maculatus
Boeke, S.J. ; Barnaud, B. ; Loon, J.J.A. van; Kossou, D.K. ; Huis, A. van; Dicke, M. - \ 2004
International Journal of Pest Management 50 (2004)4. - ISSN 0967-0874 - p. 251 - 258.
piper-guineense - stored cowpea - protectants - products - oils
Traditionally used African plant powders, with a known effect against the cowpea beetle Callosobruchus maculatus in stored cowpea, were extracted with water. The extracts, 13 volatile oils, 2 non-volatile oils and 8 slurries, were evaluated for their toxic and repellent effects against the beetle. Application of volatile oils led in most cases to a reduced number of eggs on treated beans. The volatile oils of Cymbopogon nardus and C. schoenanthus caused the majority of the eggs not to develop into adult beetles. Repellent effects were found for Clausena anisata, Cymbopogon citratus, Cymbopogon nardus, a mixture of Cymbopogon citratus and Cymbopogon flexuosus, Hyptis spicigera, Tagetes minuta and for two samples of Ocimum basilicum. Non-volatile oils were not repellent and had no effect on the number of eggs laid, but the development of these eggs was hampered, most so by Azadirachta indica oil. None of the slurries had a toxic effect on the beetles, but the slurries obtained from Carica papaya, Dracaena arborea and Tephrosia vogelii were repellent, whereas the slurry from Azadirachta indica leaves was attractive. Oils, both volatile and non-volatile, were easily extracted from plant material and showed promising results as a protective agent for stored cowpea.
Host preference of Callosobruchus maculatus: a comparison of life history characteristics for three strains of beetles on two varieties of cowpea
Boeke, S.J. ; Loon, J.J.A. van; Huis, A. van; Dicke, M. - \ 2004
Journal of Applied Entomology 128 (2004)6. - ISSN 0931-2048 - p. 390 - 396.
f coleoptera - fabricius coleoptera - egg-production - seed beetle - bruchidae - oviposition - susceptibility - resistance - fecundity - size
The reproductive success of Callosobruchus maculatus Fabricius, the main insect pest of stored cowpea, may vary between strains of this beetle and between varieties of the host seeds. Life history parameters of beetle strains from three different origins in West Africa were compared on two susceptible varieties of cowpea, Vigna unguiculata (L.) Walp. All beetle strains were assayed in a no-choice and a two-choice test. No major differences were found between the beetle strains. In a no-choice situation, the developmental period from egg to adult was prolonged on the bean variety Kpodjiguegue. In a two-choice situation, the beetles showed a strong preference for the Californian blackeyed bean variety to oviposit on. Here again the development took longer on Kpodjiguegue beans and the intrinsic rate of increase of the beetle population was lower. Using either equal numbers of beans of the same size or equal weights of beans of undetermined size of the two bean varieties did not affect the outcome of the test.
Toxicity and repellence of African plants traditionally used for the protection of stored cowpea against Callosobruchus maculatus
Boeke, S.J. ; Baumgart, I.R. ; Loon, J.J.A. van; Huis, A. van; Dicke, M. ; Kossou, D.K. - \ 2004
Journal of Stored Products Research 40 (2004)4. - ISSN 0022-474X - p. 423 - 438.
fabricius coleoptera - bruchidae - seeds
In a search for botanical products to control the main insect pest of stored cowpea, Callosobruchus maculatus, 33 traditionally used African plants were tested in the laboratory for their toxic and repellent effects against this beetle. Toxicity was evaluated measuring life history parameters in a no-choice situation. Powders of Nicotiana tabacum, Tephrosia vogelii and Securidaca longepedunculata significantly reduced the number of progeny. Repellence was evaluated by observing the behaviour of female beetles exposed to treated and untreated beans in a linear olfactometer. Clausena anisata, Dracaena arborea, T. vogelii, Momordica charantia and Blumea aurita were repellent to the beetle, whereas Chamaecrista nigricans, Azadirachta indica and Hyptis suaveolens were attractive. Our results indicate that botanical products may provide effective control of C. maculatus in cowpea.
Safety evaluation of neem (Azadirachta indica) derived pesticides
Boeke, S.J. ; Boersma, M.G. ; Alink, G.M. ; Loon, J.J.A. van; Huis, A. van; Dicke, M. ; Rietjens, I.M.C.M. - \ 2004
Journal of Ethnopharmacology 94 (2004)1. - ISSN 0378-8741 - p. 25 - 41.
nitro-n-nitrosoguanidine - buccal pouch carcinogenesis - leaf extracts - gastric carcinogenesis - blood-constituents - seed extract - male-rats - oil - toxicity - praneem
The neem tree, Azadirachta indica, provides many useful compounds that are used as pesticides and could be applied to protect stored seeds against insects. However in addition to possible beneficial health effects, such as blood sugar lowering properties, anti-parasitic, anti-inflammatory, anti-ulcer and hepatoprotective effects, also toxic effects are described. In this study we present a review of the toxicological data from human and animal studies with oral administration of different neem-based preparations. The non-aqueous extracts appear to be the most toxic neem-based products, with an estimated safe dose (ESD) of 0.002 and 12.5 g/kg bw/day. Less toxic are the unprocessed materials seed oil and the aqueous extracts (ESD 0.26 and 0.3 mg/kg bw/day, 2 l/kg bw/day respectively). Most of the pure compounds show a relatively low toxicity (ESD azadirachtin 15 mg/kg bw/day). For all preparations, reversible effect on reproduction of both male and female mammals seem to be the most important toxic effects upon sub-acute or chronic exposure. From the available data, safety assessments for the various neem-derived preparations were made and the outcomes are compared to the ingestion of residues on food treated with neem preparations as insecticides. This leads to the conclusion that, if applied with care, use of neem derived pesticides as an insecticide should not be discouraged.
Field trials with plant products to protect stored cowpea against insect damage
Boeke, S.J. ; Kossou, D.K. ; Huis, A. van; Loon, J.J.A. van; Dicke, M. - \ 2004
International Journal of Pest Management 50 (2004)1. - ISSN 0967-0874 - p. 1 - 9.
callosobruchus-maculatus-f - obtectus say coleoptera - essential oils - vigna-unguiculata - pod resistance - bruchidae - extracts - aphididae - toxicity - beetle
Plant products were evaluated under field conditions for their efficacy as insecticides against the cowpea beetle, Callosobruchus maculatus, on stored cowpea. Seeds, mixed with finely ground clay and three volatile oils were stored in air-tight jerry-cans and canisters. Pods were treated with leaf powders of two plant species and stored in traditional palm-leaf huts. Beetle damage was evaluated before and after storage. The treatments did not prevent damage, but after treatment with oils, fewer beans showed beetle emergence holes; also, the percentage of uninfested beans and the weight of one litre of beans were each higher than for untreated beans. The percentage of germination of stored beans was highest after treatment with Ocimum basilicum oil. Leaf powder of Momordica charantia was effective against weight loss of stored seeds, whereas Ficus exasperata caused a decrease in both the percentage of infested beans and the number of emerged beetles, and more parasitoids emerged than from untreated beans. Laboratory tests on the effect of the oils on the development of the beetle and on bean germination did not reveal effects of the oils. We compare data obtained from the laboratory and with those obtained in the field.
Side-effects of cowpea treatment with botanical insecticides on two parasitoids of Callosobruchus maculatus
Boeke, S.J. ; Sinzogan, A.A.C. ; Almeida, R.P. de; Boer, P.W.M. de; Jeong, G.S. ; Kossou, D.K. ; Loon, J.J.A. van - \ 2003
Entomologia Experimentalis et Applicata 108 (2003). - ISSN 0013-8703 - p. 43 - 51.
biological-control - uscana-lariophaga - f coleoptera - west-africa - bruchidae - storage - pteromalidae - hymenoptera - pests
Studies on the protective effect of botanical products against pest insects have infrequently been extended to side-effects on natural enemies. Indirect effects of botanicals on the storability of seeds could occur through their possible negative impact on biological control agents. Four plant powders and six plant oils with a known effect on the cowpea beetle Callosobruchus maculatus (Fabr.) (Coleoptera: Bruchidae) were investigated for their effect on the beetles' egg parasitoid Uscana lariophaga (Steffan) (Hymenoptera: Trichogrammatidae) and the larval parasitoid Dinarmus basalis (Rondani) (Hymenoptera: Pteromalidae). All treatments caused a decrease in parasitisation by U. lariophaga, and developing parasitoids of this species were affected by powders of Nicotiana tabacum (L.) and Tephrosia vogelii (Hook. f). In a two-choice situation using a linear olfactometer, U. lariophaga was repelled by most of the oils. In a no-choice situation, parasitisation by D. basalis was hampered by treatment with plant powders, but eggs that were laid developed normally. In a Y-tube olfactometer, this parasitoid did not discriminate between odours of untreated and plant-powder-treated beans. The powders of N. tabacum and T. vogelii had stronger negative effects on the two parasitoids than the powders of Azadirachta indica (Juss.) or Blumea aurita (DC). In samples collected from untreated traditional storage facilities, subsequently treated with plant powders in the laboratory, none of the treatments could prevent the increase in beetle numbers. At 24 days after treatment, most beetles had emerged from beans treated with powders of N. tabacum and T. vogelii. Parasitoids were affected by the botanical insecticides tested here, but the powders of A. indica and B. aurita may be compatible with biological control by D. basalis.
Traditional African plant products to protect stored cowpeas against insect damage : the battle against the beetle
Boeke, S.J. - \ 2002
Wageningen University. Promotor(en): M. Dicke; J.J.A. van Loon; A. van Huis. - S.l. : S.n. - ISBN 9789058087362 - 151
vigna unguiculata - vignabonen - callosobruchus maculatus - voorraadplagen - plantaardige insecticiden - insecticiden bevattende planten - vigna unguiculata - cowpeas - callosobruchus maculatus - stored products pests - botanical insecticides - insecticidal plants

Seeds of the cowpea plant, Vigna unguiculata , a tropical crop, are very susceptible to attack by the cowpea beetle. This specialist beetle needs only the beans to reproduce rapidly.

Most farmers in West Africa have few possibilities to treat the beans and they face their stored supply, on which they are dependent for their daily nourishment, be destroyed within a few months. From lack of other measures, these farmers traditionally used plants, stored together with the beans for protection. In the laboratory, such plants have been tested as powders and as extract for their effect against the beetle. Side effects on natural enemies of the beetle have also been tested for and in a review of the literature, effects on humans have been investigated. Together with the results from a field test in Africa, this gives a picture of the potency of local means to protect stored seeds against insects.

The use of plant material to protect stored leguminous seeds against seed beetles: a review
Boeke, S.J. ; Loon, J.J.A. van; Huis, A. van; Kossou, D.K. ; Dicke, M. - \ 2001
Leiden : Backhuys Publishers (Wageningen University papers 2001-3) - ISBN 9789057821004 - 108
voorraadplagen - coleoptera - insecticiden bevattende planten - insectenplagen - insectenafweermiddelen - bruchidae - vigna unguiculata - fabaceae - zaden - overzichten - stored products pests - seeds - insecticidal plants - insect pests - insect repellents - reviews
Methane Oxidation and the Competition for Oxygen in the Rice Rhizosphere
Bodegom, P.M. van; Stams, F. ; Mollema, L. ; Boeke, S. ; Leffelaar, P.A. - \ 2001
Applied and Environmental Microbiology 67 (2001). - ISSN 0099-2240 - p. 3586 - 3597.
A mechanistic approach is presented to describe oxidation of the greenhouse gas methane in the rice rhizosphere of flooded paddies by obligate methanotrophic bacteria. In flooded rice paddies these methanotrophs compete for available O2 with other types of bacteria. Soil incubation studies and most-probable-number (MPN) counts of oxygen consumers show that microbial oxygen consumption rates were dominated by heterotrophic and methanotrophic respiration. MPN counts of methanotrophs showed large spatial and temporal variability. The most abundant methanotrophs (a Methylocystis sp.) and heterotrophs (a Pseudomonas sp. and a Rhodococcus sp.) were isolated and characterized. Growth dynamics of these bacteria under carbon and oxygen limitations are presented. Theoretical calculations based on measured growth dynamics show that methanotrophs were only able to outcompete heterotrophs at low oxygen concentrations (frequently <5 ?M). The oxygen concentration at which methanotrophs won the competition from heterotrophs did not depend on methane concentration, but it was highly affected by organic carbon concentrations in the paddy soil. Methane oxidation was severely inhibited at high acetate concentrations. This is in accordance with competition experiments between Pseudomonas spp. and Methylocystis spp. carried out at different oxygen and carbon concentrations. Likely, methane oxidation mainly occurs at microaerophilic and low-acetate conditions and thus not directly at the root surface. Acetate and oxygen concentrations in the rice rhizosphere are in the critical range for methane oxidation, and a high variability in methane oxidation rates is thus expected.
Differences in UV-B tolerance among Spirodela punctata ecotypes
Jansen, M.A.K. ; Noort, R.E. van den; Boeke, S.J. ; Huggers, S.A.M. ; Haan, J.H. de - \ 1999
Journal of Photochemistry and Photobiology. B, Biology 48 (1999). - ISSN 1011-1344 - p. 194 - 199.
Traumatische ervaringen, gevolgen en verwerking.
Kleber, R.J. - \ 1986
University of Amsterdam (UvA). Promotor(en): P.B. Defares; P.E. Boeke. - Lisse : Swets en Zeitlinger - 278 p.
Evaluation of post-harvest trends of respiration rates and softening of apples and tomatoes
Boeke, J.E. - \ 1968
Wageningen University. Promotor(en): E.C. Wassink. - Wageningen : Veenman - 89
plantaardige producten - behandeling - appels - malus - solanum lycopersicum - tomaten - plantkunde - plant products - treatment - apples - malus - solanum lycopersicum - tomatoes - botany

Physiological functions of a specimen of fruits or vegetables in storage follow trends that are either 'normal' or 'abnormal'. Normal functioning will produce changes that are known to occur under optimal storage conditions, and that result in an optimal market quality. Abnormal functioning may lead to the appearance of the typical symptoms of a storage disease. The beginning of abnormal functioning is supposed to be marked by a deviation from one or more of the normal trends.

To detect possible deviations, trends of physiological functions of stored produce were followed. A new type of conditioning machine was used, a description of which is given in chapter 3. The apparatus allows a number of test objects (single specimens) to be viewed from all sides, without disturbing their storage conditions, and without interfering with other determinations made on the test material. The storage conditions can be kept independent from the temperature, the composition and the barometric pressure of the outer atmosphere.

One of the trends that can be followed in the conditioning machine is the CO 2 -production rate. A new method is described (chapter 4) that allows the CO 2 -production rates of seventy apples, kept at low storage temperature, to be recorded individually, within four hours, with an experimental error not exceeding 2 %. From each apple in turn, a stream of air carrying respiratory CO 2 is mixed with a flow of titrant, a solution of potassium methanolate in acetone and methanol, 0.001 to 0.004 N. The supply of titrant is adjusted until equivalent with the rate of CO 2 absorbed. Adjustment is made by means of a variable air pressure, which is read on a manometer. For a number of rates of CO 2 supply the 'equivalent manometer value' was compared with gravimetric measurement of CO 2 ; the relation between the two was linear, so that the 'equivalent manometer values' could be used as a measure of CO 2 production rates of individual apple specimens.

Deviations from 'normal' trends of CO 2 production of Jonathan apples were found to start either spontaneously (i.e., apparently not induced by an environmental factor) or to be induced by a transient change in the storage temperature. In one season, spontaneous deviations were found to start several weeks before the first symptoms of decay appeared on the surface of the fruit; in another season, this sequence was reversed. This might indicate either that the two effects do not have a common cause, or that host-parasite relationships vary from one season to another (section

A transient thermal stimulus was found to induce deviations that were either transient or apparently irreversible (section The reversible character of a deviation would show within a few days or weeks, after which the previous trend would be resumed. Irreversible deviations sometimes brought to light differences between specimens that had followed identical courses before the stimulus was applied. Also, specific differences were found: Boskoop apples showed a deviation one day later than Jonathan apples, and less pronounced.

In an Appendix, a description is given of a new closed container method for the determination of CO 2 -production rates of single specimens and of composite samples of apples and other objects.

New methods have also been tried to study softening of fruits in store. The 'METTLER Compressor' is a precision balance provided with a plunger (section 5.2.2). The 'Bellows Compressor' is a (plastic) bellows provided with a plunger; it operates by means of a variable hydrostatic pressure read on a liquid manometer (section 5.2.3).

Determinations with these compressors necessitate the transfer of test fruits from storage conditions to the apparatus.

In case the test fruits should be left in the same environment, the 'Hydraulic Sweller' and/or the 'Hydraulic Belt' are alternatives. The one can be fixed inside a fruit, the other around a fruit. Both operate by means of a variable hydrostatic pressure which causes a liquid meniscus in a transparent capillary tube to move; the displacement serves as a measure of the induced deformation. Deformations in the order of 0.005 to 0.04 mm/day were established, the experimental error being less than 0.001 mm. Such deformations, when found with the aid of a hydraulic belt, seem to be caused by both softening and shrinkage of the test fruits. Hydraulic swellers allowed the beginning of internal rotting in apple and pear fruits to be read from a distance.

The Bellows compressor, showed different manometer readings representing 'firmness values' on the equator of tomato fruits: over cross-walls, firmness values were 4.7 % ± 1.16 higher than over locules (section 5.3.4). The tomato blossom end was found to provide firmness values that were in close correlation with the grade of colouring of the fruits (section 5.3.5). In the course of time, blossom-end firmness values of tomato fruits (as determined with the bellows apparatus) gradually decreased, parallel with the change in colour (table 1). The plunger of the compressor gained 0.007 to 0.025 mm/day, the experimental error being 0.01 to 0.02 mm. These results are not affected by shrinkage of the fruits.

Tests have been made on objects that changed their consistence, within a few minutes, while being subjected to alternating pressures. In a jellifying mixture, the alternating time-deformation curves changed from rectilinear to asymptotic whereas the opposite tendency occurred in fruits that were subjected to an injurious electric current (section 5.3.7).

With the aid of a METTLER Compressor, different spots on the surface of an apple fruit were tested. They appeared to be identical as to their yield point. but different as to the point of rupture of their skin (section 5.3.2). In tomatoes, no yield point appeared, although the test resulted in a distinct indentation in the surface of the test fruit.

Economic aspects of low labour-income farming
Luning, H.A. - \ 1967
Wageningen University. Promotor(en): J.H.L. Joosten. - Wageningen : Pudoc - ISBN 9789022001608 - 137
landbouw - kleine landbouwbedrijven - werk - arbeid (werk) - theorie - economie - ontwikkelingslanden - primitieve economie - agriculture - small farms - work - labour - theory - economics - developing countries - primitive economy
Conflicting views on the relevance of economic theory, as developed in the West, to low-income peasant societies had been advanced ever since Boeke's time.

Recent literature pointed out that available economic theories did not seem to fit the behavioral motivation, assumed in economic logic. The value was. questioned of the tenet of profit-maximization and the usefulness of marginal analysis, especially with redundant labour and disguised unemployment in lowincome farming. The productivity of labour as a determinant of wage formation was emphasized. After a review of wage theories, a theoretical structure was presented of the border line of underemployment and its impact on the level of remuneration in low-income farming.

Relevant hypotheses were tested by multiple regression analysis, using the Cobb Douglas production function. Field studies were carried out among peasant farmers in Northern Nigeria and in Surinam. The indication was that labour's remuneration was in accordance with its productivity. Absorption of labour into the agricultural economy was shown to be crucial in developmental strategy. For each area of study such a strategy was designed with estimated production functions.

Gaswisseling van afzonderlijke vruchten
Boeke, J.E. ; Meer, Q.P. van der - \ 1958
Wageningen : [s.n.] (Rapport / Instituut voor bewaring en verwerking van tuinbouwproducten no. 903, 1059, 1190)
fruitteelt - nederland - plantaardige producten - behandeling - fruit growing - netherlands - plant products - treatment
Rijpheidsonderzoek van appels en peren : beproeving van de methode Doesburg
Schreven, A.C. van; Boeke, J.E. ; Meer, Q.P. van der - \ 1956
Wageningen : [s.n.] (Rapport / Instituut voor bewaring en verwerking van tuinbouwproducten no. 700) - 17
appels - plantkunde - nederland - peren - apples - botany - netherlands - pears
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