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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    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.

    Getting prepared for future attack : induction of plant defences by herbivore egg deposition and consequences for the insect community
    Pashalidou, F.G. - \ 2015
    Wageningen University. Promotor(en): Marcel Dicke; Joop van Loon, co-promotor(en): Nina Fatouros. - Wageningen : Wageningen University - ISBN 9789462574120 - 168
    insect-plant relaties - planten - insectenplagen - herbivorie - verdedigingsmechanismen - geïnduceerde resistentie - herbivoor-geinduceerde plantengeuren - ovipositie - natuurlijke vijanden - brassica - pieris brassicae - trofische graden - sluipwespen - hyperparasitoïden - insectengemeenschappen - insect plant relations - plants - insect pests - herbivory - defence mechanisms - induced resistance - herbivore induced plant volatiles - oviposition - natural enemies - brassica - pieris brassicae - trophic levels - parasitoid wasps - hyperparasitoids - insect communities

    Plants have evolved intriguing defences against insect herbivores. Compared to constitutive Plants have evolved intriguing defences against insect herbivores. Compared to constitutive defences that are always present, plants can respond with inducible defences when they are attacked. Insect herbivores can induce phenotypic changes in plants and consequently these changes may differentially affect subsequent attackers and their associated insect communities. Many studies consider herbivore-feeding damage as the first interaction between plants and insects. The originality of this study was to start with the first phase of herbivore attack, egg deposition, to understand the consequences of plant responses to eggs on subsequently feeding caterpillars and their natural enemies. The main plant species used for most of the experiments was Brassica nigra (black mustard), which occurs naturally in The Netherlands. The main herbivore used was the lepidopteran Pieris brassicae, which lays eggs in clusters and feeds on plants belonging to the Brassicaceae family. This study investigated plant-mediated responses to oviposition and their effects on different developmental stages of the herbivore, such as larvae and pupae. Furthermore, the effects of oviposition were extended to four more plant species of the same family, and to higher trophic levels including parasitoids and hyperparasitoids. The experiments were conducted under laboratory, semi-field and field conditions. This study shows that B. nigra plants recognize the eggs of P. brassicae and initiate resistance against subsequent developmental stages of the herbivore. Interestingly, plant responses to oviposition were found to be species specific. Plants did not respond to egg deposition by another herbivore species, the generalist moth Mamestra brassicae. Moreover, most of the Brassicaceae species tested were found to respond to P. brassicae eggs, which indicates that plant responses against oviposition are more common among the family of Brassicaceae. To assess effects on other members of the food chain, the effects of oviposition on plant volatile emission and the attraction of parasitic wasps, such as the larval parasitoid Cotesia glomerata, were tested. It was shown that the wasps were able to use the blend of plant volatiles, altered by their hosts’ oviposition, to locate young caterpillars just after hatching from eggs. The observed behaviour of the wasps was associated with higher parasitism success and higher fitness in young hosts. Similar results were obtained in a field experiment, where plants infested with eggs and caterpillars attracted more larval parasitoids and hyperparasitoids and eventually produced more seeds compared to plants infested with caterpillars only. This study shows that an annual weed like B. nigra uses egg deposition as reliable information for upcoming herbivory and responds accordingly with induced defences. Egg deposition could influence plant-associated community members at different levels in the food chain and benefit seed production. As the importance of oviposition on plant-herbivore interactions is only recently discovered, more research is needed to elucidate the mechanisms that underlie such plant responses and how these interactions affect the structure of insect communities in nature.

    Host preference and offspring performance are linked in three congeneric hyperparasitoid species
    Harvey, J.A. ; Gols, R. ; Snaas, H. ; Malcicka, M. ; Visser, B. - \ 2015
    Ecological Entomology 40 (2015)2. - ISSN 0307-6946 - p. 114 - 122.
    monoctonus-paulensis hymenoptera - optimal bad motherhood - parasitoid wasps - reproductive strategies - sex allocation - age preference - lysibia-nana - braconidae - ichneumonidae - oviposition
    1. The optimisation theory predicts that insect mothers should oviposit on resources on which they attain the highest exclusive fitness. The development of parasitoid wasps is dependent on limited host resources that are often not much larger than the adult parasitoid. 2. In the present study preference and development in three congeneric species of secondary hyperparasitoids attacking cocoons of two congeneric primary parasitoids that differ significantly in size were compared. Gelis agilis (Fabricius) and G. acarorum (L.) are wingless hyperparasitoids that forage in grassy habitats, whereas G. areator (Panzer) is fully winged and forages higher in the canopy of forbs. 3. The three species were reared on cocoons containing pupae of a small gregarious endoparasitoid, Cotesia glomerata (L.), and a larger solitary species, C. rubecula (Marshall), both of which develop in the caterpillars of pierid butterflies. 4. Adult mass was correlated with initial cocoon mass in all three species, whereas development time was unaffected. Wasps were larger when developing in C. rubecula. However, for a given host mass, wasps were larger when developing on the smaller host, C. glomerata. This suggests that there is a physiological limit to hyperparasitoid size that was exceeded when C. rubecula served as host. 5. All three hyperparasitoids strongly preferred to attack cocoons of the larger species, C. rubecula, often avoiding cocoons of C. glomerata entirely. 6. Preference and performance are correlated in the three Gelis species. However, owing to variation in the distribution and thus abundance of their hosts, it is argued that cumulative fitness may be still higher in the smaller host species.
    Drought stress affects plant metabolites and herbivore preference but not host location by its parasitoids
    Weldegergis, B.T. ; Zhu, F. ; Poelman, E.H. ; Dicke, M. - \ 2015
    Oecologia 177 (2015)3. - ISSN 0029-8549 - p. 701 - 713.
    volatile emissions - water-stress - abiotic factors - oviposition - genes - biosynthesis - consequences - lepidoptera - complexity - expression
    One of the main abiotic stresses that strongly affects plant survival and the primary cause of crop loss around the world is drought. Drought stress leads to sequential morphological, physiological, biochemical and molecular changes that can have severe effects on plant growth, development and productivity. As a consequence of these changes, the interaction between plants and insects can be altered. Using cultivated Brassica oleracea plants, the parasitoid Microplitis mediator and its herbivorous host Mamestra brassicae, we studied the effect of drought stress on (1) the emission of plant volatile organic compounds (VOCs), (2) plant hormone titres, (3) preference and performance of the herbivore, and (4) preference of the parasitoid. Higher levels of jasmonic acid (JA) and abscisic acid (ABA) were recorded in response to herbivory, but no significant differences were observed for salicylic acid (SA) and indole-3-acetic acid (IAA). Drought significantly impacted SA level and showed a significant interactive effect with herbivory for IAA levels. A total of 55 VOCs were recorded and the difference among the treatments was influenced largely by herbivory, where the emission rate of fatty acid-derived volatiles, nitriles and (E)-4,8-dimethylnona-1,3,7-triene [(E)-DMNT] was enhanced. Mamestra brassicae moths preferred to lay eggs on drought-stressed over control plants; their offspring performed similarly on plants of both treatments. VOCs due to drought did not affect the choice of M. mediator parasitoids. Overall, our study reveals an influence of drought on plant chemistry and insect-plant interactions.
    To be in time: egg deposition enhances plant-mediated detection of young caterpillars by parasitoids
    Pashalidou, F.G. ; Gols, R. ; Berkhout, B.W. ; Weldegergis, B.T. ; Loon, J.J.A. van; Dicke, M. ; Fatouros, N.E. - \ 2015
    Oecologia 177 (2015)2. - ISSN 0029-8549 - p. 477 - 486.
    different larval instars - pieris-brassicae - specialist herbivore - volatile emissions - cotesia-glomerata - host location - oviposition - responses - maize - generalist
    Animals use information from their environment while foraging for food or prey. When parasitic wasps forage for hosts, they use plant volatiles induced by herbivore activities such as feeding and oviposition. Little information is available on how wasps exploit specific plant volatiles over time, and which compounds indicate changes in host quality. In experiments investigating the role of herbivore-induced plant volatiles in wasp foraging, induction of plant response is usually achieved by placing larvae on clean plants instead of allowing the natural sequence of events: to let eggs deposited by the herbivore develop into larvae. We compared the attraction of the parasitoid Cotesia glomerata to volatiles emitted by black mustard (Brassica nigra) plants induced by eggs and successive larval stages of the Large Cabbage White butterfly (Pieris brassicae) to the attraction of this parasitoid to black mustard plant volatiles induced only by larval feeding in a wind tunnel setup. We show that wasps are attracted to plants infested with eggs just before and shortly after larval hatching. However, wasp preference changed at later time points towards plants induced only by larval feeding. These temporal changes in parasitoid attraction matched with changes in the chemical compositions of the blends of plant volatiles. Previous studies have shown that host quality/suitability decreases with caterpillar age and that P. brassicae oviposition induces plant defences that negatively affect subsequently feeding caterpillars. We investigated parasitoid performance in hosts of different ages. Wasp performance was positively correlated with preference. Moreover, parasitism success decreased with time and host stage. In conclusion, the behaviour of Cotesia glomerata is fine-tuned to exploit volatiles induced by eggs and early host stages that benefit parasitoid fitness.
    Synergistic effects of direct and indirect defences on herbivore egg survival in a wild crucifer
    Fatouros, N.E. ; Pineda, A. ; Huigens, M.E. ; Broekgaarden, C. ; Shimwela, M.M. ; Figueroa Candia, I.A. ; Verbaarschot, P. ; Bukovinszky, T. - \ 2014
    Proceedings of the Royal Society. B: Biological Sciences 281 (2014)1789. - ISSN 0962-8452 - 9 p.
    furcifera horvath homoptera - plant defense - trade-offs - antiherbivore defenses - natural enemies - fitness costs - brassica-rapa - resistance - oviposition - butterflies
    Evolutionary theory of plant defences against herbivores predicts a trade-off between direct (anti-herbivore traits) and indirect defences (attraction of carnivores) when carnivore fitness is reduced. Such a trade-off is expected in plant species that kill herbivore eggs by exhibiting a hypersensitive response (HR)-like necrosis, which should then negatively affect carnivores. We used the black mustard (Brassica nigra) to investigate how this potentially lethal direct trait affects preferences and/or performances of specialist cabbage white butterflies (Pieris spp.), and their natural enemies, tiny egg parasitoid wasps (Trichogramma spp.). Both within and between black mustard populations, we observed variation in the expression of Pieris egg-induced HR. Butterfly eggs on plants with HR-like necrosis suffered lower hatching rates and higher parasitism than eggs that did not induce the trait. In addition, Trichogramma wasps were attracted to volatiles of egg-induced plants that also expressed HR, and this attraction depended on the Trichogramma strain used. Consequently, HR did not have a negative effect on egg parasitoid survival. We conclude that even within a system where plants deploy lethal direct defences, such defences may still act with indirect defences in a synergistic manner to reduce herbivore pressure.
    Effectiviteit van Middel X voor de beheersing van champignonmuggen (Lycoriella castanescens) in de champignonteelt
    Baars, J.J.P. ; Rutjens, A.J. - \ 2012
    Wageningen : Plant Research International, Business Unit Plant Breeding (Report / Plant Research International 2012-6) - 15
    eetbare paddestoelen - champignonmest - lycoriella auripila - bestrijdingsmethoden - behandeling - proefopzet - substraten - ovipositie - edible fungi - mushroom compost - lycoriella auripila - control methods - treatment - experimental design - substrates - oviposition
    Dit rapport beschrijft de resultaten van onderzoek naar de effectiviteit van Middel X ter bestrijding van champignonmuggen in de teelt van champignons. De effectiviteit werd onderzocht door ge-CACte dekaarde op een commercieel teeltbedrijf voor eiafzetting aan te bieden aan de aanwezige populatie champignonmuggen. Vervolgens werd de ge-CACte dekaarde behandeld met het equivalent van 2, 4 of 6 ml Middel X/m2 teeltoppervlak. Hiervoor werd Middel X op twee verschillende manieren toegepast; als een begieting op de dekaarde of gemengd door de dekaarde. Ter controle werd Dimilin (werkzame stof diflubenzuron) in halve dosering (1 ml Dimilin/m2) of normale dosering (2 ml Dimilin/m2) toegepast middels een begieting op de dekaarde. De conclusie is dat Middel X niet geschikt is voor de bestrijding van champignonmuggen in de champignonteelt. Daarnaast is gebleken dat entbare compost beter geschikt is als substraat voor de kweek van champignonmuggen dan ge-CACte dekaarde of doorgroeide compost.
    Plant Volatiles Induced by Herbivore Egg Deposition Affect Insects of Different Trophic Levels
    Fatouros, N.E. ; Lucas-Barbosa, D. ; Weldegergis, B.T. ; Pashalidou, F.G. ; Loon, J.J.A. van; Dicke, M. ; Harvey, J.A. ; Gols, R. ; Huigens, M.E. - \ 2012
    PLoS ONE 7 (2012)8. - ISSN 1932-6203
    furcifera horvath homoptera - elm leaf beetle - whitebacked planthopper - cotesia-glomerata - herbaceous plants - pieris-brassicae - host location - rice plants - oviposition - defense
    Plants release volatiles induced by herbivore feeding that may affect the diversity and composition of plant-associated arthropod communities. However, the specificity and role of plant volatiles induced during the early phase of attack, i.e. egg deposition by herbivorous insects, and their consequences on insects of different trophic levels remain poorly explored. In olfactometer and wind tunnel set-ups, we investigated behavioural responses of a specialist cabbage butterfly (Pieris brassicae) and two of its parasitic wasps (Trichogramma brassicae and Cotesia glomerata) to volatiles of a wild crucifer (Brassica nigra) induced by oviposition of the specialist butterfly and an additional generalist moth (Mamestra brassicae). Gravid butterflies were repelled by volatiles from plants induced by cabbage white butterfly eggs, probably as a means of avoiding competition, whereas both parasitic wasp species were attracted. In contrast, volatiles from plants induced by eggs of the generalist moth did neither repel nor attract any of the tested community members. Analysis of the plant’s volatile metabolomic profile by gas chromatography-mass spectrometry and the structure of the plant-egg interface by scanning electron microscopy confirmed that the plant responds differently to egg deposition by the two lepidopteran species. Our findings imply that prior to actual feeding damage, egg deposition can induce specific plant responses that significantly influence various members of higher trophic levels.
    Whether ideal free or not, predatory mites distribute so as to maximize reproduction
    Hammen, T. van der; Montserrat, M. ; Sabelis, M.W. ; Roos, A.M. ; Janssen, A. - \ 2012
    Oecologia 169 (2012)1. - ISSN 0029-8549 - p. 95 - 104.
    free distribution models - unequal competitors - egg predation - interference - density - prey - phytoseiidae - oviposition - tests
    Ideal free distribution (IFD) models predict that animals distribute themselves such that no individual can increase its fitness by moving to another patch. Many empirical tests assume that the interference among animals is independent of density and do not quantify the effects of density on fitness traits. Using two species of predatory mites, we measured oviposition as a function of conspecific density. Subsequently, we used these functions to calculate expected distributions on two connected patches. We performed an experimental test of the distributions of mites on two such connected patches, among which one had a food accessibility rate that was twice as high as on the other. For one of the two species, Iphiseius degenerans, the distribution matched the expected distribution. The distribution also coincided with the ratio of food accessibility. The other species, Neoseiulus cucumeris, distributed itself differently than expected. However, the oviposition rates of both species did not differ significantly from the expected oviposition rates based on experiments on single patches. This suggests that the oviposition rate of N. cucumeris was not negatively affected by the observed distribution, despite the fact that N. cucumeris did not match the predicted distributions. Thus, the distribution of one mite species, I. degenerans, was in agreement with IFD theory, whereas for the other mite species, N. cucumeris, unknown factors may have influenced the distribution of the mites. We conclude that density-dependent fitness traits provide essential information for explaining animal distributions
    Behavioural effects of fungal infection by Metarhizium anisopliae in adult malaria mosquitoes
    Ondiaka, S.N. - \ 2012
    Wageningen University. Promotor(en): Willem Takken; Marcel Dicke, co-promotor(en): W.R. Mukabana. - S.l. : s.n. - ISBN 9789461732934 - 179
    anopheles gambiae - vectoren, ziekten - malaria - vectorbestrijding - biologische bestrijding - metarhizium anisopliae - diergedrag - paringsgedrag - gedrag bij zoeken van een gastheer - voedingsgedrag - ovipositie - anopheles gambiae - disease vectors - malaria - vector control - biological control - metarhizium anisopliae - animal behaviour - mating behaviour - host-seeking behaviour - feeding behaviour - oviposition

    Malaria remains a major global health problem with the burden of disease greatest in Sub-Saharan Africa. The strategies for malaria control differ throughout the world according to levels of endemicity and the magnitude of disease but the focus remains either to control malaria parasites or vectors. A high degree of drug resistance and the absence of malaria vaccines are a major hindrance to control of the disease. In such circumstances, vector control becomes an alternative and has remained the most effective means to prevent malaria transmission. Contemporary adult mosquito control is almost exclusively based on indoor application of chemical insecticides in the form of indoor residual spraying (IRS) of walls and ceilings and insecticide-impregnated bed nets. However, sustainable use of chemicals is undermined by problems of insecticide resistance in mosquito populations, environmental contamination and risks to human health. Biological control based on fungal pathogens has shown potential to complement existing vector control methods. The entomopathogenic fungi (EPF) Metarhizium anisopliae and Beauveria bassiana have demonstrated ability to infect, kill and reduce the survival of malaria vectors. However, the effect of EPF on the behaviour of malaria vectors has not been fully addressed.

    This thesis was designed to provide baseline information on mosquito-fungus interaction focusing on the efficacy of entomopathogenic fungus M. anisopliae ICIPE 30 on the important life-history behaviours of the African malaria vector Anopheles gambiae Giles sensu stricto under laboratory and semi-field conditions. The information is important to facilitate the further development of malaria vector control based on biological control agents. Host-seeking, sugar-feeding, mating and oviposition were the behaviours investigated. Since mosquito-fungus contact is crucial for infection with EPF, a paper sheet (28.6 × 14.3 cm) lined inside a plastic cylinder (9-cm diameter and 15-cm height) was developed as a cost effective method of infection. Moreover, 0.1 g (approx. 1011 conidia/m2) of dry conidia and 6 hr exposure time sufficient for An. gambiae to pick up large numbers of conidia were established to cause high pathogenicity (Chapter 3). As the impact of EPF on insect behaviour was reported to occur at least three days post-exposure to fungal pathogen (Chapter 2), all experiments were conducted with a special focus on mosquitoes three days post-exposure to fungus. It is, however, important to mention that on average 50% of the mosquitoes died on the third day after fungal exposure (Chapter 3) and only those that survived were used for behavioural assays.

    The host-seeking capability of An. gambiae mosquitoes is an important parameter in the vectorial capacity equation. At short-range (1 m from host) assessment using a dual-choice olfactometer under semi-field conditions, infection with EPF strongly reduced the host-seeking response of mosquitoes, but did not impair their olfactory-based capability to discriminate between hosts (Chapter 4). At medium-range, using experimental cages (3 x 3 x 2 m) under laboratory conditions, fungal infection reduced the host-seeking response and feeding propensity of female An. gambiae mosquitoes (Chapter 7) whereas at long-range (7 m from host) inside a semi-field enclosure, infection with EPF sharply reduced the house-entry response and the hourly human-biting responses of host-seeking mosquitoes indoors and outdoors (Chapter 5). Plant sugar feeding is an important component in the biology of mosquitoes and is the main priority for both sexes at emergence. Infection with fungal pathogen strongly reduced the survival and sugar-feeding propensity of both sexes of the malaria vector An. gambiae but did not affect their potential to feed and digest meals (Chapter 6). Mating behaviour plays a key role in population growth. The activity takes place after sugar feeding and thereafter, the females search for their blood meal host. Infection with M. anisopliae strongly reduced multiple mating propensity and the mating performance of adult male An. gambiae mosquitoes in a large arena such as a screenhouse. Although this resulted in a reduction in the number of females inseminated, it facilitated the transfer of fungal conidia to conspecific healthy females during mating (Chapter 8). Finally, after blood meal intake, the females prepare to lay eggs. Infection with M. anisopliae reduced the oviposition propensity of female An. gambiae mosquitoes although the number of eggs laid remained unaffected (Chapter 7).

    In conclusion, these findings demonstrate that the entomopathogenic fungus M. anisopliae alters the major life history behaviours of An. gambiae mosquitoes. This is possible because the fungus strongly impairs flight performance of mosquitoes that makes the insect less able to fly and engage in host-seeking, sugar-feeding, mating and oviposition behaviours. The high mortalities observed in the early days of infection prior to conducting behavioural assays, mortalities observed while conducting behavioural assays and a reduction in behavioural response of M. anisopliae-infected mosquitoes collectively are likely to have a significant impact in suppressing a vector population. The susceptibility of male mosquitoes to fungal conidia opens a new strategy for mosquito vector control. Overall, this thesis has demonstrated that EPF may be a good complement to other mosquito vector control tools for the reduction of mosquito bites, and transmission of malaria and other mosquito-borne diseases.

    Resource use of specialist butterflies in agricultural landscapes: conservation lessons from the butterfly Phengaris (Maculinea) nausithous
    Jansen, S.H.D.R. ; Holmgren, M. ; Langevelde, F. van; Wynhoff, I. - \ 2012
    Journal of Insect Conservation 16 (2012)6. - ISSN 1366-638X - p. 921 - 930.
    large blue butterflies - host-ant specificity - calcareous grasslands - european butterflies - land-use - oviposition - lepidoptera - habitat - lycaenidae - teleius
    Most of the European grassland butterfly species are dependent on species rich grasslands shaped by low intensity farming. Conservation of these specialist species in agricultural landscapes relies on knowledge of their essential resources and the spatial distribution of these resources. In The Netherlands, the dusky large blue Phengaris (Maculinea) nausithous butterflies were extinct until their reintroduction in 1990. In addition, a spontaneous recolonization of road verges in an agricultural landscape occurred in 2001 in the southern part of The Netherlands. We analyzed the use of the essential resources, both host plants and host ants, of the latter population during the summers of 2003 and 2005. First we tested whether the distribution of the butterflies during several years could be explained by both the presence of host plants as well as host ants, as we expected that the resource that limits the distribution of this species can differ between locations and over time. We found that oviposition site selection was related to the most abundant resource. While in 2003, site selection was best explained by the presence of the host ant Myrmica scabrinodis, in 2005 it was more strongly related to flowerhead availability of the host plant. We secondly compared the net displacement of individuals between the road verge population and the reintroduced population in the Moerputten meadows, since we expected that movement of individuals depends on the structure of their habitat. On the road verges, butterflies moved significantly shorter distances than on meadows, which limits the butterflies in finding their essential resources. Finally we analyzed the availability of the two essential resources in the surroundings of the road verge population. Given the short net displacement distances and the adverse landscape features for long-distance dispersal, this landscape analysis suggests that the Phengaris population at the Posterholt site is trapped on the recently recolonized road verges. These results highlight the importance of assessing the availability of essential resources across different years and locations relative to the movement of the butterflies, and the necessity to careful manage these resources for the conservation of specialist species in agricultural landscapes, such as this butterfly species
    Field attraction of the vine weevil Otiorhynchus sulcatus to Kairomones
    Tol, R.W.H.M. van; Bruck, D.J. ; Griepink, F.C. ; Kogel, W.J. de - \ 2012
    Journal of Economic Entomology 105 (2012)1. - ISSN 0022-0493 - p. 169 - 175.
    olfactory antennal responses - plant volatiles - host plants - fruit-fly - curculionidae - coleoptera - strawberry - oviposition - pheromone - varieties
    Root weevils in the genus Otiorhynchus are cited as one of the most important pests in the major nursery and small fruit production areas throughout the United States, western Canada, and northern Europe. A major problem in combating weevil attack is monitoring and timing of control measures. Because of the night-activity of the adult weevils growers do not observe the emerging weevils in a timely manner and oviposition often starts before effective control measures are taken. Several vine weevil electroantennogram-active plant volatiles were identiÞed from a preferred host plant, Euonymus fortunei. Main compounds evoking antennal responses on the weevilsÕ antennae were (Z)-2-pentenol, (E)-2-hexenol, (Z)-3-hexenol, methyl benzoate, linalool, (E)-4,8-dimethyl-1,3,7- nonatriene, methyl eugenol, and (E, E)-_-farnesene. Several of these compounds were tested alone and in mixtures on attractiveness for the vine weevil Otiorhynchus sulcatus (F.) in Þeld-grown strawberry in Oregon. O. sulcatus were attracted to (Z)-2-pentenol (_3_ more than control) and a 1:1 ratio mixture of (Z)-2-pentenol and methyl eugenol (4.5_ more than control). This is the Þrst report of Þeld-active attractants for O. sulcatus which holds promise for the development of new monitoring strategies for growers in the near future
    Identification of silverleaf whitefly resistance in pepper
    Firdaus, S. ; Heusden, S. van; Harpenas, Asep ; Supena, E.D.J. ; Visser, R.G.F. ; Vosman, B. - \ 2011
    Plant Breeding 130 (2011)6. - ISSN 0179-9541 - p. 708 - 714.
    bemisia-argentifolii homoptera - hirsutum f-glabratum - trialeurodes-vaporariorum - sweet-pepper - wild tomato - aleyrodidae - tabaci - oviposition - cotton - insecticide
    Whitefly is economically one of the most threatening pests of pepper worldwide, which is mainly caused by its ability to transmit many different viruses. In this research, we characterized pepper germplasm to identify whitefly-resistant accessions that will form the basis for future resistance breeding. Forty-four pepper accessions representing four species (Capsicum annuum, C. frutescens, C. chinense, C. baccatum) were screened for resistance to whiteflies. Screening parameters were adult survival (AS) and oviposition rate (OR) in a no-choice test and whitefly, egg and nymphal density in free-choice tests. To combine parameters in free-choice tests, a plant resistance value was calculated. The results show that AS and OR were significantly different among accessions and were positively correlated, which was also the case for the parameters in the free-choice tests. Accessions identified as highly resistant in no-choice and free-choice tests generally were C. annuum. Whitefly density and OR correlated positively with trichome density and negatively with cuticle thickness of leaves.
    Not only the butterflies: managing ants on road verges to benefit Phengaris (Maculinea) butterflies
    Wynhoff, I. ; Gestel, R. van; Swaay, C. van; Langevelde, F. van - \ 2011
    Journal of Insect Conservation 15 (2011)1-2. - ISSN 1366-638X - p. 189 - 206.
    large blue - myrmica-scabrinodis - species richness - host-ants - habitat - restoration - oviposition - populations - grasslands - diversity
    Obligate myrmecophilic butterfly species, such as Phengaris (Maculinea) teleius and P. nausithous, have narrow habitat requirements. Living as a caterpillar in the nests of the ant species Myrmica scabrinodis and M. rubra, respectively, they can only survive on sites with both host ants and the host plant Great Burnet Sanguisorba officinalis. After having been reintroduced into a nature reserve in the Netherlands in 1990, both butterfly species expanded their distribution to linear landscape elements such as road verges and ditch edges outside this reserve. As additional habitat of both butterfly species, vegetation management of these landscape elements became important. Our results show that a management beneficial for Phengaris butterflies should aim to increase the nest density of Myrmica species, at the same time reducing the density of nests of the competitor Lasius niger or at least keeping them at a low density. Unfavourable grassland management under which L. niger thrives, includes not mowing or flail-cutting the grass, or depositing dredgings along the side of the ditch. Management favourable for the two Myrmica species differs, demanding some flexibility if both species are to benefit. M. scabrinodis is best supported with early mowing of the road verge vegetation or late mowing in the nature reserve, both of which result in an open vegetation and warm microclimate. In contrast, the nest sites of M. rubra should be left undisturbed during the summer, and mown in late autumn. Mowing of butterfly habitat should be avoided between mid-June and mid-September as this would remove the flowerheads of the Sanguisorba plants, on which the butterflies lay their eggs.
    Assessing risks and benefits of floral supplements in conservation biological control
    Winkler, K. ; Wackers, F.L. ; Termorshuizen, A.J. ; Lenteren, J.C. van - \ 2010
    BioControl 55 (2010)6. - ISSN 1386-6141 - p. 719 - 727.
    diamondback moth - euphydryas-chalcedona - field conditions - honeydew sugars - nectar sources - lepidoptera - parasitoids - resources - oviposition - herbivores
    The use of flowering field margins is often proposed as a method to support biological control in agro-ecosystems. In addition to beneficial insects, many herbivores depend on floral food as well. The indiscriminate use of flowering species in field margins can therefore lead to higher pest numbers. Based on results from field observations and laboratory experiments we assessed risks as well as benefits associated with the provision of nectar plants in field margins, using Brussels sprouts as a model system. Results show that Brussels sprouts bordered by nectar plants suitable for the cabbage white Pieris rapae L., suffered higher infestation levels by this herbivore. In contrast, nectar plants providing accessible nectar for the diamondback moth Plutella xylostella L., did not raise densities of P. xylostella larvae in the Brassica crop. Margins with Anethum graveolens L., selected on the basis of its suitability as nectar plant for parasitoids, significantly increased the number of adult Diadegma semiclausum Hellen in the crop. This didn't translate into enhanced parasitism rates, as parasitism of P. xylostella by D. semiclausum exceeded 65 % in all treatments, irrespective of the plants in the field margin. Our findings emphasize the importance of taking a multitrophic approach when choosing flowering field margin plants for biocontrol or other ecosystem services
    Tarsal taste neuron activity and proboscis extension reflex in response to sugars and amino acids in Helicoverpa armigera (Hübner)
    Zhang, Y.F. ; Loon, J.J.A. van; Wang, C.Z. - \ 2010
    Journal of Experimental Biology 213 (2010). - ISSN 0022-0949 - p. 2889 - 2895.
    pyrameis atalanta linn - cabbage root fly - heliothis-virescens - contact chemoreceptors - feeding responses - pieris-brassicae - inachis-io - oviposition - nectar - sensitivity
    In adult female Helicoverpa armigera (Hübner), the fifth tarsomere of the prothoracic legs bears 14 gustatory trichoid chemosensilla. These chemosensilla were characterized through electrophysiological experiments by stimulating with sucrose, glucose, fructose, maltose, myo-inositol and 20 common amino acids. In electrophysiological recordings from nine sensilla, responses were obtained to certain compounds tested at 100 mmol l–1, and the response spectra differed from broad to narrow. The four sugars excited the same receptor neuron in sensillum a and sensillum b; sucrose and myo-inositol, sucrose and lysine, myo-inositol and lysine excited two different receptor neurons respectively in sensillum a; fructose and lysine excited two different receptor neurons in sensillum n. Furthermore, the four sugars, myo-inositol and lysine all elicited concentration-dependent electrophysiological responses. These six compounds also induced the proboscis extension reflex (PER) followed by ingestion of the solution when they were applied on the tarsi. Lysine and sucrose caused the strongest electrophysiological responses. However, sucrose had the strongest stimulatory effect on the PER whereas lysine had the weakest. Mixtures of sucrose with the other sugars or with lysine had a similar stimulatory effect on the PER as sucrose alone. The electrophysiological and behavioural responses caused by a range of sucrose concentrations were positively correlated. We conclude that the tarsal gustatory sensilla play an essential role in perceiving sugars available in floral nectar and provide chemosensory information determining feeding behaviour. Tarsal taste-receptor-neuron responses to lysine are implicated in oviposition behaviour.
    Anti-aphrodisiac compounds of male butterflies increase the risk of egg parasitoid attack by inducing plant synomone production
    Fatouros, N.E. ; Pashalidou, F.G. ; Aponte Cordero, W.V. ; Loon, J.J.A. van; Mumm, R. ; Dicke, M. ; Hilker, M. ; Huigens, M.E. - \ 2009
    Journal of Chemical Ecology 35 (2009)11. - ISSN 0098-0331 - p. 1373 - 1381.
    pieris-rapae - methyl salicylate - predatory mite - defense responses - pinus-sylvestris - cabbage white - host location - insect - volatiles - oviposition
    During mating in many butterfly species, males transfer spermatophores that contain anti-aphrodisiacs to females that repel conspecific males. For example, males of the large cabbage white, Pieris brassicae (Lepidoptera: Pieridae), transfer the anti-aphrodisiac, benzyl cyanide (BC) to females. Accessory reproductive gland (ARG) secretion of a mated female P. brassicae that is deposited with an egg clutch contains traces of BC, inducing Brussels sprouts plants (Brassica oleracea var. gemmifera) to arrest certain Trichogramma egg parasitoids. Here, we assessed whether deposition of one egg at a time by the closely related small cabbage white, Pieris rapae, induced B. oleracea var. gemmifera to arrest Trichogramma wasps, and whether this plant synomone is triggered by substances originating from male P. rapae seminal fluid. We showed that plants induced by singly laid eggs of P. rapae arrest T. brassicae wasps three days after butterfly egg deposition. Elicitor activity was present in ARG secretion of mated female butterflies, whereas the secretion of virgin females was inactive. Pieris rapae used a mixture of methyl salicylate (MeSA) and indole as an anti-aphrodisiac. We detected traces of both anti-aphrodisiacal compounds in the ARG secretion of mated female P. rapae, whereas indole was lacking in the secretion of virgin female P. rapae. When applied onto the leaf, indole induced changes in the foliar chemistry that arrested T. brassicae wasps. This study shows that compounds of male seminal fluid incur possible fitness costs for Pieris butterflies by indirectly promoting egg parasitoid attack
    The effect of water turbidity on the near-surface water temperature of larval habitats of the malaria mosquito Anopheles gambiae
    Paaijmans, K.P. ; Takken, W. ; Githeko, A.K. ; Jacobs, A.F.G. - \ 2008
    International Journal of Biometeorology 52 (2008)8. - ISSN 0020-7128 - p. 747 - 753.
    western kenya - spatial-distribution - culicidae larvae - aquatic stages - sensu-lato - arabiensis diptera - giles complex - oviposition - survival - simulations
    Water temperature is an important determinant in many aquatic biological processes, including the growth and development of malaria mosquito (Anopheles arabiensis and A. gambiae) immatures. Water turbidity affects water temperature, as suspended particles in a water column absorb and scatter sunlight and hence determine the extinction of solar radiation. To get a better understanding of the relationship between water turbidity and water temperature, a series of semi-natural larval habitats (diameter 0.32 m, water depth 0.16 m) with increasing water turbidity was created. Here we show that at midday (1300 hours) the upper water layer (thickness of 10 mm) of the water pool with the highest turbidity was on average 2.8 degrees C warmer than the same layer of the clearest water pool. Suspended soil particles increase the water temperature and furthermore change the temperature dynamics of small water collections during daytime, exposing malaria mosquito larvae, which live in the top water layer, longer to higher temperatures.
    Male-derived butterfly anti-aphrodisiac mediates induced indirect plant defense
    Fatouros, N.E. ; Broekgaarden, C. ; Bukovinszkine-Kiss, G. ; Loon, J.J.A. van; Mumm, R. ; Huigens, M.E. ; Dicke, M. ; Hilker, M. - \ 2008
    Proceedings of the National Academy of Sciences of the United States of America 105 (2008). - ISSN 0027-8424 - p. 10033 - 10038.
    parasitic wasps - pierid butterflies - oral secretions - gene-expression - host location - atp synthase - insect - elicitors - volatiles - oviposition
    Plants can recruit parasitic wasps in response to egg deposition by herbivorous insects¿a sophisticated indirect plant defense mechanism. Oviposition by the Large Cabbage White butterfly Pieris brassicae on Brussels sprout plants induces phytochemical changes that arrest the egg parasitoid Trichogramma brassicae. Here, we report the identification of an elicitor of such an ovipositioninduced plant response. Eliciting activity was present in accessory gland secretions released by mated female butterflies during egg deposition. In contrast, gland secretions from virgin female butterflies were inactive. In the male ejaculate, P. brassicae females receive the anti-aphrodisiac benzyl cyanide (BC) that reduces the females¿ attractiveness for subsequent mating. We detected this pheromone in the accessory gland secretion released by mated female butterflies. When applied onto leaves, BC alone induced phytochemical changes that arrested females of the egg parasitoid. Microarray analyses revealed a similarity in induced plant responses that may explain the arrest of T. brassicae to egg-laden and BC-treated plants. Thus, a male-derived compound endangers the offspring of the butterfly by inducing plant defense. Recently, BC was shown to play a role in foraging behavior of T. brassicae, by acting as a cue to facilitate phoretic transport by mated female butterflies to oviposition sites. Our results suggest that the antiaphrodisiac pheromone incurs fitness costs for the butterfly by both mediating phoretic behavior and inducing plant defense.
    The response specificity of Trichogramma egg parasitoids towards infochemicals during host location
    Fatouros, N.E. ; Bukovinszkine-Kiss, G. ; Dicke, M. ; Hilker, M. - \ 2007
    Journal of Insect Behavior 20 (2007)1. - ISSN 0892-7553 - p. 53 - 65.
    pieris-brassicae l - evanescens westwood - behavioral variations - mamestra-brassicae - biological-control - strains - hymenoptera - oviposition - lepidoptera - kairomones
    Parasitoids are confronted with many different infochemicals of their hosts and food plants during host selection. Here, we investigated the effect of kairomones from the adult host Pieris brassicae and of cues present on Brussels sprout plants infested by P. brassicae eggs on the behavioral response of the egg parasitoid Trichogramma evanescens. Additionally, we tested whether the parasitoid¿s acceptance of P. brassicae eggs changes with different host ages. The wasps did not discriminate between olfactory cues from mated and virgin females or between mated females and males of P. brassicae. T. evanescens randomly climbed on the butterflies, showing a phoretic behavior without any preference for a certain sex. The parasitoid was arrested on leaf parts next to 1-day-old host egg masses. This arrestment might be due to cues deposited during oviposition. The wasps parasitized host eggs up to 3 days old equally well. Our results were compared with former studies on responses by T .brassicae showing that T. evanescens makes less use of infochemicals from P. brassicae than T. brassicae.
    Reconstruction of fig wasp mating structure: how many mothers share a fig?
    Zavodna, M. ; Knapp, S.M. ; Compton, S.G. ; Arens, P.F.P. ; Vosman, B. ; Dijk, P.J. ; Gilmartin, P.M. ; Damme, J.M.M. van - \ 2007
    Ecological Entomology 32 (2007)5. - ISSN 0307-6946 - p. 485 - 491.
    sex-ratios - pollinating wasps - social-behavior - consequences - evolution - oviposition - populations - strategies - allocation - mutualism
    1.¿Fig wasps (Hymenoptera: Agaonidae) represent an important model system for studies of sex ratio evolution, mainly because they may adjust their sex ratios in response to the numbers of ovipositing females (foundresses) that enter a fig and their clutch size. 2.¿Until recently, it was assumed that all foundresses fail to re-emerge from the figs that they have entered to oviposit, but there is increasing evidence that such re-emergence may be routine. The common practice of counting the number of dead foundresses present in a fig in order to deduce the number of foundresses is therefore questionable in species where failure to re-emerge has not been confirmed. 3.¿In this study, the alternative approach of microsatellite markers was used to reconstruct the within-fig breeding structure of a pollinating fig wasp by genetic analysis of the offspring. Broods of Liporrhopalum tentacularis, a species where foundresses regularly re-emerge from figs, were collected from figs of Ficus montana in their natural habitat in Indonesia as well as from an experimental glasshouse population in Leeds (U.K.). 4.¿The estimated foundress densities in the glasshouse population were similar to those in the field and ranged from one to six foundresses per brood. 5.¿Nearly 40% of all broods were produced by a single foundress, indicating that mating in these broods occurs exclusively between full siblings. High levels of inbreeding are therefore common in this species.
    Associative learning of visual and gustatory cues in the large cabbage white butterfly, Pieris brassicae
    Smallegange, R.C. ; Everaarts, T.C. ; Loon, J.J.A. van - \ 2006
    Animal Biology 56 (2006)2. - ISSN 1570-7555 - p. 157 - 172.
    helicoverpa-armigera - pipevine swallowtail - phytophagous insects - color preferences - foraging behavior - papilio-xuthus - leaf shape - rapae - oviposition - evolution
    The landing response of the large cabbage white butterfly Pieris brassicae was studied under controlled optical and gustatory stimulus conditions. Experience-based changes in landing behaviour were examined by offering cardboard circles of two different shades of green, treated with either an oviposition stimulant or a deterrent. We employed two training situations. In one situation the two shades of green, carrying either the stimulant or the deterrent, were offered simultaneously, in the other sequentially. During the 1 hour training periods, butterflies were either landing and drumming spontaneously or they were caught at the end of the period and placed on the artificial leaves until tarsal drumming ensued. Our experiments demonstrated that P. brassicae females can learn to associate visually detected substrate characteristics with contact-chemosensory information available only after landing. Furthermore, a learned preference for a substrate could be turned into a preference for the alternative substrate by exposing the insect to a deterrent on the previously preferred substrate. These results provide indications of aversion learning, thus far undocumented in oviposition behaviour of Lepidoptera. Bringing the butterflies into forced contact with the oviposition stimulant resulted in similar effects on landing preference compared to those of spontaneous landing, but spontaneous landing had a stronger effect on preference for associations involving the deterrent. The simultaneous training regime, which supposedly requires a less important role for short-term memory, was more effective in modifying landing preferences
    Influence of adult nutrition on the relationship between body size and reproductive parameters in a parasitoid wasp
    Bezemer, T.M. ; Harvey, J.A. ; Mills, N.J. - \ 2005
    Ecological Entomology 30 (2005)5. - ISSN 0307-6946 - p. 571 - 580.
    clutch size - egg-production - bracon-hebetor - host - fitness - hymenoptera - life - field - age - oviposition
    1. An important constraint upon life-history evolution in parasitoids is the limit imposed by body size on allocation of limited metabolic resources to different fitness-related physiological functions such as reproduction and survival. 2. The influence of adult nutrition on reproductive and maintenance variables was studied in the synovigenic ectoparasitoid Mastrus ridibundus, and it was determined whether resource allocation to these different functions depends on body size. 3. Over the course of adult life there was a positive relationship between body size and the number of mature eggs in adult females both in the presence and absence of food. However, only in the presence of food did egg maturation rates increase significantly with body size. Starved wasps produced significantly smaller eggs than fed ones, which has not been documented before. Moreover, starved wasps produced fewer offspring than fed wasps, and attacked fewer hosts. 4. The availability of food had a major effect on longevity, with fed females living about 10 times longer than starved ones. There was also a positive relationship between body size and longevity. In starved wasps, this relationship was the same both in the presence and absence of hosts, but in fed wasps there was a positive relationship between body size and longevity in the absence of hosts only. Allocation to initial eggs relative to lifetime progeny production did not decline with body size. 5. The data reveal that in M. ridibundus the trade-off between maintenance and reproduction varies with life expectancy
    Host plant preference and performance of the vine weevil Otiorhynchus sulcatus
    Tol, R.W.H.M. van; Dijk, N. van; Sabelis, M.W. - \ 2004
    Agricultural and Forest Entomology 6 (2004)4. - ISSN 1461-9555 - p. 267 - 278.
    curculionidae - coleoptera - strawberry - oviposition - resistance - responses - clones
    1. The relationship between reproductive performance and preference for potential host plants of the vine weevil is investigated, as shown in tests on contact (or feeding) preference, presented herein, and tests on olfactory preference, published elsewhere. 2. Assessment of reproductive performance shows that the host-plant range of the adult vine weevil Otiorhynchus sulcatus in Europe is limited to one gymnosperm genus (Taxus sp.) and a broad range of angiosperm plants in two subclasses of the Dicotyledonae, namely Dilleniidae and Rosidae. The successful reproduction on very distantly related plant taxa suggests that the original weevil- and plant-habitat has mediated the current host-plant range of the vine weevil. 3. Contact-preference tests with equally suitable hosts, such as Aronia, Fragaria, Euonymus and Taxus, and one less suitable host, Humulus, indicate a mismatch between contact preference and performance and, as far as olfactory preferences are known, these match neither the contact preferences nor the performance. This mismatch may arise because (i) host plant species offered do not occur in weevil habitat in Europe (e.g. Aronia and the cultivated Fragaria come from North America) and (ii) predation (or disease) risks differ among host plants, thereby altering effective reproductive performance. 4. With respect to performance on novel hosts (Thuja, Prunus) and bad hosts (Rhododendron), some between-individual variation is found within a single population, suggesting that local populations harbour (possibly genetic) variation for adaptation to new hosts. How this variation is maintained in the face of strong selection pressures on local populations of flightless and thelytokous weevils, is an important question for understanding the broad host plant range in the vine weevil
    Egg laying site preferences in Pterostichus melanarius Illiger (Coleoptera: Carabidae)
    Trefas, H. ; Lenteren, J.C. van - \ 2004
    Proceedings of the Netherlands Entomological Society meeting 15 (2004). - ISSN 1874-9542 - p. 105 - 109.
    hordeum vulgare - brassica oleracea var. gemmifera - plantenplagen - natuurlijke vijanden - pterostichus melanarius - ovipositie - biologische bestrijding - hordeum vulgare - brassica oleracea var. gemmifera - plant pests - natural enemies - pterostichus melanarius - oviposition - biological control
    In the case of ground beetles, the number of studies investigating the effects plant-related structure and microclimate on the selection of egg laying sites is very limited. The egg laying site preference of Pterostichus melanarius, an important carabid beetle in agricultural fields, was studied under laboratory conditions. The effects of wet/dry substrate, light/shadow and structured/unstructured environment on the number of eggs laid were investigated, as well as the influence of the presence of barley and Brussels sprout plants. We found that there was a strong influence of plant structure and microclimate on the selection of egg laying sites. Results showed a higher numbers of eggs laid in barley compared to Brussels sprouts. These results were supported by a significant preference for moist, shadowed, structurally complex environments as egg laying sites. Results indicate that vegetation characteristics in themselves may influence egg laying site preferences, beside the availability of prey for the adults and larvae, in the different plant systems.
    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.
    Plant competition in pest-suppressive intercropping systems complicates evaluation of herbivore responses
    Bukovinszky, T. ; Tréfás, H. ; Lenteren, J.C. van; Vet, L.E.M. ; Fremont, J. - \ 2004
    Agriculture, Ecosystems and Environment 102 (2004). - ISSN 0167-8809 - p. 185 - 196.
    brevicoryne-brassicae l - host-plant - population-dynamics - cruciferous plants - brussels-sprouts - pieris-rapae - oviposition - diversity - insect - performance
    In the light of current theories on the effects of intercropping on pest reduction, population responses of the diamondback moth (Plutella xylostella), the cabbage aphid (Brevicoryne brassicae) and the life history traits of the large white butterfly (Pieris brassicae) were studied in a Brussels sprout (Brassica oleracea gemmifera)/malting barley (Hordeum vulgare) additive row intercrop and a Brussels sprout monoculture. More P. xylostella adults were caught in the monoculture than in the intercrop. Numbers of R xylostella larvae and pupae per sprout plant were lower in intercropped plots than in monocultures. However, more larvae and pupae were found per m(2) leaf area in the inter- than in the monocrop. Both the densities per plant and per m(2) leaf area of B. brassicae populations were lower in the inter- than in the monocrop. After the barley withered and competition with Brussels sprout abated, aphid densities became higher in the inter- than in the monocrop. These findings may be explained by interspecific plant competition resulting in stressed sprout plants with a smaller size and delayed phenology relative to monocropped plants. Effects of differences in plant nutritional quality on herbivore performance were studied by offering leaves of inter- and monocropped sprout plants to larval R brassicae. Performance and food utilisation were significantly better on leaves from the intercrop, (lower dry weight consumption, higher growth rates) than from the monocrop. Defoliation rate was also higher on leaves of intercropped plants than on monocropped ones. The studies indicate that plant stress and consequent changes in developmental rate and nutritional quality of plants are playing a role in herbivore population responses to intercropping. It is argued that such confounding effects of plant competition in intercropping designs can hamper the evaluation of herbivore responses in pest-suppressive agro-ecosystems. (C) 2003 Elsevier B.V. All rights reserved.
    Predicting the temperature-dependent natural population expansion of the western corn rootworm, Diabrotica virgifera
    Hemerik, L. ; Busstra, M.C. ; Mols, P. - \ 2004
    Entomologia Experimentalis et Applicata 111 (2004). - ISSN 0013-8703 - p. 59 - 69.
    coleoptera-chrysomelidae - leconte coleoptera - oviposition - velocity - flight - patterns - northern - dynamics - barberi - spread
    The western corn rootworm, Diabrotica virgifera virgifera Leconte (Coleoptera: Chrysomelidae), was accidentally introduced near Belgrade in Serbia just before 1992 and from there its expansion into Europe started. We have estimated its mean rate of expansion from 1992 to 2000 to be approximately 33 km year(-1), using data from the annual surveys of the European and Mediterranean Plant Protection Organisation. We investigated whether or not D. virgifera can establish itself at certain places in Europe, taking its temperature-dependent development into account. We also estimated the time it will take D. virgifera to reach the Netherlands, considering only its dispersal by flight. All life stage transitions of D. virgifera were simulated with the program INSIM to assess whether or not it could establish itself in particular places. In the simulations, we used the available laboratory data on its life history characteristics, as well as a time series (2-6 years) of daily minimum and maximum temperatures from weather stations across Europe. The temperature-dependent net reproduction resulting from the simulations showed that D. virgifera populations cannot establish themselves at latitudes above 55degreesN. The overall expected velocity of D. virgifera's range expansion was computed with van den Bosch et al.'s formula [van den Bosch F, Hengeveld R & Metz JAJ (1992) Analysing the velocity of animal range expansion. Journal of Biogeography 19: 135-150], where the expansion velocity was based on dispersal characteristics and demographic parameters. We predicted that D. virgifera will not reach the Netherlands by flight from the border of its 2000 range before 2018 using this overall expected velocity. The explanation of this late arrival is that the velocity of population expansion decreases in all directions from the centre of its 2000 range due to unfavourable temperatures. Our analysis is an improvement on former analyses in that it uses temperature-dependent life history characteristics. We stress, however, that the lack of knowledge on dispersal behaviour and on the values of life history characteristics in field situations might severely limit the applicability of the predicted velocity.
    Food preference of wireworms analyzed with multinomial logit models
    Hemerik, L. ; Gort, G. ; Brussaard, L. - \ 2003
    Journal of Insect Behavior 16 (2003). - ISSN 0892-7553 - p. 647 - 665.
    feeding-preference - host-plant - beetles coleoptera - elateridae - curculionidae - chrysomelidae - grasslands - oviposition - specificity - collembola
    Many species of wireworms (larvae of click beetles, Elateridae) are polyphagous root herbivores. In grasslands under restoration succession with various grass species, we aim to determine the role of wireworms in aboveground vegetation succession. Therefore, it is crucial to know whether wireworms prefer some food plants to others. We have investigated the root preference to different grass species for Agriotes obscurus and Athous haemorrhoidalis and whether these preferences can be explained by covariates. In Experiment 1, individual wireworms could choose between four different plants, one of each species (Anthoxanthum odoratum, Festuca rubra, Holcus lanatus, and Lolium perenne). In Experiment 2, groups of wireworms were released into the soil in the center of 16 plants (4 from each species). We used multinomial logit models (MLMs) to analze the data. In the appendix the use of multinomial response models is clarified with a fictitious example, using the SAS statistic software package. No preference was found in Experiment 1. In Experiment 2 we found differences in attractiveness of plant species depending on wireworm species: A. obscurus preferred grass species from nutrient-rich grasslands (L. perenne and H. lanatus). Both wireworm species disliked F. rubra. The distance from the release point influenced the probability of being found at a certain place at the end of the experiment: wireworms tended to stay in the proximity of the release point. A. haemorrhoidalis was more often found farther from the point of release than A. obscurus. Dispersal was farther from the release point in experiments with young plants (6 weeks) compared to older ones (9 weeks). Results are discussed in a broad ecological context.
    Effects of prey mite species on life history of the phytoseiid predators Typhlodromalus manihoti and Typhlodromalus aripo
    Gnanvossou, D. ; Yaninek, J.S. ; Hanna, R. ; Dicke, M. - \ 2003
    Experimental and Applied Acarology 30 (2003). - ISSN 0168-8162 - p. 265 - 278.
    cassava green mite - acari - preference - africa - food - tetranychidae - oviposition - kairomone - survival - rates
    The effects of prey mite suitability on several demographic characteristics of phytoseiid predators and the relationship of these effects to the potential of phytoseiid predators to control herbivorous mite populations are well documented. Evidence has also accumulated in the last 20 years demonstrating that phytoseiid predators utilize herbivorous prey mite-induced plant volatiles as olfactory cues in locating their herbivorous mite prey, but less well established is the predictability of reproductive success from the ability of the predators to utilize olfactory cues to locate their prey, and how these processes are related to the success of the predators as biological control agents of the herbivorous mite. In this study, we determined in laboratory no choice experiments, the development, survivorship and fecundity of the two neotropical phytoseiid predators Typhlodromalus manihoti Moraes and T. aripo DeLeon when feeding on three herbivorous mites, including the key prey species Mononychellus tanajoa (Bondar), and the two alternative prey species Oligonychus gossypii (Zacher) and Tetranychus urticae (Koch). Intrinsic rate of increase (rm) of T. aripo was 2.1 fold higher on M. tanajoa as prey compared with T. urticae as prey, while it was almost nil on O. gossypii. For T. manihoti, rm was 2.3 fold higher on M. tanajoa as prey compared with O. gossypii as prey, while reproduction was nil on T. urticae. An independent experiment on odor-related prey preference of the two predator species (Gnanvossou et al. 2002) showed that T. manihoti and T. aripo preferred odors from M. tanajoa-infested leaves to odors from O. gossypii-infested leaves. Moreover, both predator species preferred odors from M. tanajoa-infested leaves over those from T. urticae-infested leaves. As reported here, life history of the two predatory mites matches odor-related prey preference if the key prey species is compared to the two inferior prey species. The implications of our findings for the persistence of T. manihoti and T. aripo and biological control of M. tanajoa in the cassava agroecosystem in Africa are discussed.
    Cannibalism and predation among larvae of the Anopheles gambiae complex
    Koenraadt, C.J.M. ; Takken, W. - \ 2003
    Medical and Veterinary Entomology 17 (2003). - ISSN 0269-283X - p. 61 - 66.
    giles complex - arabiensis diptera - western kenya - culicidae - density - identification - oviposition - selection - mosquitos - habitats
    Among the aquatic developmental stages of the Anopheles gambiae complex (Diptera: Culicidae), both inter- and intra-specific interactions influence the resulting densities of adult mosquito populations. For three members of the complex, An. arabiensis Patton, An. quadriannulatus (Theobald) and An. gambiae Giles sensu stricto , we investigated some aspects of this competition under laboratory conditions. First-instar larvae were consumed by fourth-instar larvae of the same species (cannibalism) and by fourth-instar larvae of other sibling species (predation). Even when larvae were not consumed, the presence of one fourth-instar larva caused a significant reduction in development rate of first-instar larvae. Possible implications of these effects for population dynamics of these malaria vector mosquitoes are discussed.
    Invloed voersamenstelling op broedresultaten
    Haar, J.W. van der; Lourens, S. - \ 1999
    Praktijkonderzoek voor de Pluimveehouderij 10 (1999)3. - ISSN 0924-9087 - p. 12 - 16.
    vleeskuikens - hennen - ovipositie - voer - samenstelling - maïs - tarwe - vruchtbaarheid - vleeskuikenouderdieren - broilers - hens - oviposition - feeds - composition - maize - wheat - fertility - broiler breeders
    Bij Praktijkonderzoek Pluimveehouderij Het Spelderholt (PP) is onderzocht of een voer met 50 maos betere broedresultaten oplevert dan een voer met 50 tarwe. Bij de overschakeling op 53 weken leeftijd op voer van een andere samenstelling en structuur vonden we bij de groep met 50 maos in het voer een daling van het percentage gezonde kuikens dat uit de bevruchte eieren is uitgekomen.
    Tussentijdse resultaten onderzoek leghennen in batterijen
    Emous, R.A. van; Reuvekamp, B.F.J. ; Niekerk, Th.G.C.M. van - \ 1999
    Praktijkonderzoek voor de Pluimveehouderij 10 (1999)3. - ISSN 0924-9087 - p. 4 - 11.
    hennen - batterijhuisvesting - diervoedering - voer - samenstelling - linoleenzuur - eiwitten - ovipositie - snavelkappen - lichtregiem - bezettingsdichtheid - productiviteit - hens - battery husbandry - animal feeding - feeds - composition - linolenic acid - proteins - oviposition - debeaking - light regime - stocking density - productivity
    Eind december 1998 is een nieuw koppel leghennen geplaatst in de batterijstal van het Praktijkonderzoek Pluimveehouderij Het Spelderholt. Diverse onderwerpen worden onderzocht, waarvan we enkele tussentijdse resultaten in dit artikel bespreken. De eindresultaten zijn in het voorjaar van 2000 bekend.
    Ontwikkeling lichaamsgewichten zesde koppel voor de batterijstal leghennen
    Emous, R.A. van; Reuvekamp, B.F.J. ; Niekerk, Th.G.C.M. van - \ 1999
    Praktijkonderzoek voor de Pluimveehouderij 10 (1999)2. - ISSN 0924-9087 - p. 7 - 12.
    hennen - kippen - pluimveehokken - batterijkooien - belichting - lichtregiem - verlichting - licht - groei - massa - gewicht - ontwikkeling - productiviteit - rentabiliteit - diervoedering - voer - dierfysiologie - ovipositie - agrarische bedrijfsvoering - snavelkappen - fysische factoren - dierverzorging - hens - fowls - poultry housing - battery cages - illumination - light regime - lighting - light - growth - mass - weight - development - productivity - profitability - animal feeding - feeds - animal physiology - oviposition - farm management - debeaking - physical factors - care of animals
    In de batterijstal van het Praktijkonderzoek Pluimveehouderij Het Spelderholt (PP) is in december 1998 een nieuw koppel leghennen opgezet. Gedurende de opfok waren al verschillen aangebracht op het gebied van verlichtingsschema's en snavelbehandeling.In dit artikel gaan we in op het verloop en de resultaten van de opfokperiode.
    Legnestgebruik bij het Voletage systeem
    Haar, J.W. van der - \ 1998
    Praktijkonderzoek voor de Pluimveehouderij 9 (1998)4. - ISSN 0924-9087 - p. 26 - 29.
    vleeskuikens - pluimveehokken - diergedrag - ovipositie - productie - vleeskuikenouderdieren - broilers - poultry housing - animal behaviour - oviposition - production - broiler breeders
    Bij het Praktijkonderzoek Pluimveehouderij (PP) is voor de derde maal onderzocht welke technische resultaten met vleeskuikenouderdieren zijn te behalen in het Voletage systeem. Na de tweede proef zijn bij dit systeem enkele aanpassingen aangebracht waarvan verwacht werd dat ze mogelijk ook invloed hebben op het legnestgebruik.
    Waterrantsoenering bij leghennen op batterijen
    Niekerk, Th.G.C.M. van; Reuvekamp, B.F.J. ; Ellen, H.H. ; Rommers, J.M. - \ 1997
    Beekbergen : Praktijkonderzoek Pluimveehouderij (PP uitgave : praktijkonderzoek pluimveehouderij 60) - 67
    drinken - drinkwater - hennen - batterijhuisvesting - gerantsoeneerde voeding - ovipositie - dierlijke meststoffen - drijfmest - drinking - drinking water - hens - battery husbandry - restricted feeding - oviposition - animal manures - slurries
    Reeds enige tijd wordt in de praktijk geëxperimenteerd met het rantsoeneren van water bij leghennen, teneinde luxe consumptie en vermorsing van water tegen te gaan. Dit wordt gedaan door het beperken van de tijd dat water ter beschikking is.
    Alternatieve huisvesting leghennen
    Niekerk, Th.G.C.M. van; Reuvekamp, B.F.J. - \ 1997
    Beekbergen : Praktijkonderzoek Pluimveehouderij (PP uitgave : praktijkonderzoek pluimveehouderij 57) - 89
    hennen - pluimveehokken - dierenwelzijn - huisvesting, dieren - batterijhuisvesting - ovipositie - productiviteit - rentabiliteit - dierhouderij - groepshuisvesting - hens - poultry housing - animal welfare - animal housing - battery husbandry - oviposition - productivity - profitability - animal husbandry - group housing
    In 1993 is het Praktijkonderzoek Pluimveehouderij gestart met een nieuw onderzoek: 'Alternatieve huisvesting voor leghennen', ofwel kortweg 'project 1030'. Dit project wordt bijna volledig door het bedrijfsleven betaald. Uitgangspunt bij dit onderzoekis niet alleen het verbeteren van het welzijn van leghennen, maar ook het zoveel mogelijk behouden van het economisch en arbeidstechnisch voordeel van de batterij. Er wordt dus gezocht naar een compromis tussen de wensen van de leghen en die van de pluimveehouder. In het onderzoek zijn de volgende zaken onderzocht: het scharrelsysteem, verschillende aanpassingen aan het bestaande batterijsysteem en de zogenaamde welzijnskooi (een groepskooi).
    Resultaten bij witte en bruine kunststof roosters
    Haar, J.W. van der - \ 1997
    Praktijkonderzoek voor de Pluimveehouderij 8 (1997)1. - ISSN 0924-9087 - p. 13 - 16.
    vleeskuikens - vruchtbaarheid - bevruchting - vloeren - roostervloeren - infertiliteit - ligstro - ovipositie - stallen - vleeskuikenouderdieren - broilers - fertility - fertilization - floors - grid floors - infertility - litter - oviposition - stalls - broiler breeders
    Praktijkonderzoek Pluimveehouderij (PP) heeft bij vleeskuikenouderdieren onderzocht of de kleur van kunststof roosters invloed had op het legnestgebruik. Bij de witte was het legnestgebruik net zo goed als bij de bruine.
    Tussentijdse resultaten onderzoek leghennen in batterijen
    Niekerk, Th.G.C.M. van; Reuvekamp, B.F.J. - \ 1996
    Praktijkonderzoek voor de Pluimveehouderij 7 (1996)3. - ISSN 0924-9087 - p. 4 - 7.
    batterijhuisvesting - snavelkappen - drogen - voer - hennen - mest - ovipositie - eiwitten - triticum aestivum - tarwe - battery husbandry - debeaking - drying - feeds - hens - manures - oviposition - proteins - triticum aestivum - wheat
    In februari van 1996 is een nieuw koppel leghennen in de batterijstal van PP geplaatst. Er worden weer diverse onderwerpen onderzocht: vroegrijpheid, tarwe bijvoeren, laag-eiwitvoer, snavelkappen en mestdroging.
    Vleeskuikenouderdieren: het broedeigewicht als richtlijn bij gecontroleerd voeren
    Haar, J.W. van der - \ 1996
    Praktijkonderzoek voor de Pluimveehouderij 7 (1996)2. - ISSN 0924-9087 - p. 20 - 24.
    diervoedering - broedsheid - ontwikkeling - eierproductie - voedingsrantsoenen - groei - uitbroeden - ovipositie - vleeskuikenouderdieren - animal feeding - broodiness - development - egg production - feed rations - growth - hatching - oviposition - broiler breeders
    Om bij vleeskuikenouderdieren een goede broedeiproductie te realiseren en de voerkosten zo laag mogelijk te houden, moet er voldoende, maar niet teveel voer aan de hennen worden verstrekt. De voergift zal dan ook regelmatig aangepast moeten worden.
    Eikwaliteit bij welzijnskooien niet beter ondanks maatregelen
    Reuvekamp, B.F.J. ; Niekerk, Th.C.G.M. van - \ 1996
    Praktijkonderzoek voor de Pluimveehouderij 7 (1996)2. - ISSN 0924-9087 - p. 11 - 15.
    huisvesting, dieren - dierlijke producten - dierenwelzijn - batterijhuisvesting - hennen - ovipositie - kwaliteit - animal housing - animal products - animal welfare - battery husbandry - hens - oviposition - quality
    Over het algemeen zijn de legprestaties van de hennen in de welzijnskooien goed. Helaas is de eikwaliteit ronduit slecht te noemen. Door de nesten aan te passen is getracht de positie van de hennen in het legnest te beonvloeden. Dit zou tot een verbetering van de eikwaliteit moeten leiden.
    Vleeskuikenouderdieren: het gebruik van een automatisch dierweegsysteem bij het voeren naar legpercentage en groei
    Haar, J.W. van der - \ 1996
    Praktijkonderzoek voor de Pluimveehouderij 7 (1996)1. - ISSN 0924-9087 - p. 22 - 26.
    diervoedering - automatisering - weegschalen - ontwikkeling - eierproductie - groei - mechanisatie - ovipositie - weegapparaten - vleeskuikenouderdieren - animal feeding - automation - balances - development - egg production - growth - mechanization - oviposition - weighers - broiler breeders
    Bij vleeskuikenouderdieren komt een belangrijk deel van de kosten voor rekening van het voer. Om de voerkosten laag te houden moet de voergift afgestemd worden op het legpercentage en de groei van de dieren. Naast een goed inzicht in de eiproduktie moet men ook een goed inzicht hebben in de gewichtsontwikkeling van de dieren. Bij Praktijkonderzoek Pluimveehouderij (PP) is onderzocht welke rol een automatisch dierweegsysteem hierbij kan spelen.
    Legnest in batterijkooi
    Niekerk, Th.G.C.M. van - \ 1995
    Praktijkonderzoek voor de Pluimveehouderij 6 (1995)4. - ISSN 0924-9087 - p. 13 - 18.
    dierlijke producten - batterijhuisvesting - eierproducten - eieren - nesten - ovipositie - pluimveehokken - kwaliteit - animal products - battery husbandry - egg products - eggs - nests - oviposition - poultry housing - quality
    In dit artikel wordt ingegaan op het inbrengen van een legnest in een batterijkooi. De resultaten tot nu toe geven aan, dat de hennen graag gebruik maken van het nest, maar dat er nog duidelijke problemen zijn met betrekking tot de eikwaliteit.
    Vroegrijpheid bij vleeskuikenouderdieren
    Haar, J.W. van der - \ 1994
    Beekbergen : Praktijkonderzoek Pluimveehouderij (PP uitgave : praktijkonderzoek pluimveehouderij 17) - 21
    ovipositie - vleesproductie - vleeskuikens - productiviteit - rentabiliteit - dierhouderij - vleeskuikenouderdieren - oviposition - meat production - broilers - productivity - profitability - animal husbandry - broiler breeders
    Bij Praktijkonderzoek Pluimveehouderij is onderzocht of het vroeger leg- en geslachtsrijp maken van vleeskuikenouderdieren voordelen oplevert.
    Soort opfokvoer geen invloed op legresultaten
    Reuvekamp, B.F.J. - \ 1994
    Praktijkonderzoek voor de Pluimveehouderij 5 (1994)2. - ISSN 0924-9087 - p. 6 - 8.
    diervoedering - eierproductie - hennen - ovipositie - jonge dieren - animal feeding - egg production - hens - oviposition - young animals
    Gedurende de 2e ronde met leghennen onderzoeken we of het soort voer, dat verstrekt is tijdens de opfok invloed heeft op de resultaten in de legperiode. Op een kleine uitzondering na zijn er geen verschillen in legprestaties.
    Multiphasic growth in the layer pullet : effects of nutrient restrictions during rearing
    Kwakkel, R.P. - \ 1994
    Agricultural University. Promotor(en): M.W.A. Verstegen; G. Hof. - S.l. : Kwakkel - ISBN 9789054852445 - 189
    hennen - diervoedering - jonge dieren - gerantsoeneerde voeding - groei - ontwikkeling - productiviteit - rentabiliteit - dierhouderij - ovipositie - eieren - eierproducten - hens - animal feeding - young animals - restricted feeding - growth - development - productivity - profitability - animal husbandry - oviposition - eggs - egg products

    Traditionally, layer pullets are reared on a least-cost basis. Feeding regimens, that allow pullets to consume a restricted amount of nutrients, have been designed to control body growth towards a 'target' weight and age. It was questioned whether the pattern of body growth in relation to the rate of development of particular organs during rearing interferes with the productive potential of the young hen. For the present study, it was hypothesized that the supply of nutrients for some organs may be critical at certain ages, as a result of their individual growth patterns. In this thesis, growth and development of the pullet body and its constituents has been studied by means of multiphasic growth functions. It was found that body weight at end of rearing ('target weight') is less important than type (which nutrient?) and phase (what age?) of restriction in determining egg performance. Furthermore, a pronounced growth spurt in the body growth curve was distinguished at around 19 wk of age ('the maturity growth spurt'), that appeared to be related to both the development of the reproductive organs and the onset of lay. The assessment of this growth spurt in a flock may help the producer in taking nutritional decisions. A certain amount of fat-free tissue in the body is suggested to be critical for the initiation of sexual growth. Fat growth at early rearing seemed to be functionally related to growth of the fat-free body: pullets on a low-lysine diet did not increase their fat-to-protein ratio at that stage of development. Fat growth at late rearing is stored as an energy buffer (abdominal fat pad). The composition of the fat-free body was not affected by dietary treatment. It was concluded that the fatfree body of pullets is a better measure of physiological age than body weight. Effects of nutrient restrictions on growth of body constituents should be presented relative to the fat-free body. Multiphasic analyses of pullet growth quantified some growth relationships between body components which had not been revealed if a simple monophasic growth approach had been used.

    Tussentijdse resultaten leghennen
    Niekerk, Th.G.C.M. van - \ 1992
    Praktijkonderzoek voor de Pluimveehouderij 3 (1992)3. - ISSN 0924-9087 - p. 9 - 11.
    lucht - luchtverontreiniging - ammoniak - dierlijke meststoffen - emissie - voer - hennen - hygiëne - massa - voedingswaarde - ovipositie - pluimveehokken - drijfmest - vervluchtiging - gewicht - air - air pollution - ammonia - animal manures - emission - feeds - hens - hygiene - mass - nutritive value - oviposition - poultry housing - slurries - volatilization - weight
    De eerste ronde in de nieuwe batterijstal van het Praktijkonderzoek is nu halverwege. Hoewel nog niet van alle proeven evenveel resultaten bekend zijn, lijkt het toch een goed moment om de stand van zake te bekijken.
    Vergelijking etage- en batterijhuisvesting, de vierde ronde
    Hiskemuller, W.G.M. - \ 1992
    Praktijkonderzoek voor de Pluimveehouderij 3 (1992)2. - ISSN 0924-9087 - p. 13 - 15.
    huisvesting, dieren - dierhouderij - dierenwelzijn - batterijkooien - kleur - hennen - ovipositie - pluimveehokken - productiviteit - rentabiliteit - groepshuisvesting - animal housing - animal husbandry - animal welfare - battery cages - colour - hens - oviposition - poultry housing - productivity - profitability - group housing
    De vierde ronde is, voor wat de legperiode betreft, ingegaan op 17 oktober 1991. Dit is dus een tussentijds verslag tot en met week 46. Naast de vergelijking van etage- en batterijhuisvesting speelt nu ook het verschil tussen witte en bruine hennen een belangrijke rol in deze proef.
    Laatste ronde legnestenonderzoek in Delden
    Haar, J.W. van der - \ 1992
    Praktijkonderzoek voor de Pluimveehouderij 3 (1992)1. - ISSN 0924-9087 - p. 20 - 22.
    huisvesting, dieren - dierenwelzijn - hennen - nesten - ovipositie - pluimveehokken - animal housing - animal welfare - hens - nests - oviposition - poultry housing
    Op het Pluimveeteeltproefbedrijf in Delden is al meerdere jaren onderzoek verricht naar de bruikbaarheid van automatische legnesten in de vermeerderingssector. In de laatste ronde van het onderzoek in Delden werden met het Jansen nest weer de beste resultaten behaald.
    Gecontroleerd voeren bij slachtkuikenouderdieren
    Haar, J.W. van der - \ 1991
    Praktijkonderzoek voor de Pluimveehouderij 2 (1991)4. - ISSN 0924-9087 - p. 19 - 22.
    dierhouderij - dierlijke meststoffen - voedingsrantsoenen - vruchtbaarheid - bevruchting - infertiliteit - ovipositie - productiviteit - rentabiliteit - gerantsoeneerde voeding - drijfmest - vleeskuikenouderdieren - animal husbandry - animal manures - feed rations - fertility - fertilization - infertility - oviposition - productivity - profitability - restricted feeding - slurries - broiler breeders
    Bij slachtkuikenouderdieren wordt de voergift meestal vastgesteld aan de hand van het legpercentage. Door ook rekening te houden met het lichaamsgewicht kan er wellicht bespaard worden op de voerkosten.
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