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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    High-throughput phenotyping of plant resistance to aphids by automated video tracking
    Kloth, K.J. ; Broeke, C.J.M. ten; Thoen, H.P.M. ; Hanhart-van den Brink, M. ; Wiegers, G.L. ; Krips, O.E. ; Noldus, L.P.J.J. ; Dicke, M. ; Jongsma, M.A. - \ 2015
    Plant Methods 11 (2015). - ISSN 1746-4811 - 14 p.
    green peach aphid - nasonovia-ribisnigri - glucosinolate accumulation - signaling pathways - defense responses - feeding-behavior - myzus-persicae - lettuce aphid - arabidopsis - herbivores
    Background: Piercing-sucking insects are major vectors of plant viruses causing significant yield losses in crops.Functional genomics of plant resistance to these insects would greatly benefit from the availability of highthroughput, quantitative phenotyping methods. Results: We have developed an automated video tracking platform that quantifies aphid feeding behaviour on leaf discs to assess the level of plant resistance. Through the analysis of aphid movement, the start and duration of plant penetrations by aphids were estimated. As a case study, video tracking confirmed the near-complete resistance of lettuce cultivar ‘Corbana’ against Nasonovia ribisnigri (Mosely), biotype Nr:0, and revealed quantitative resistance in Arabidopsis accession Co-2 against Myzus persicae (Sulzer). The video tracking platform was benchmarked against Electrical Penetration Graph (EPG) recordings and aphid population development assays. The use of leaf discs instead of intact plants reduced the intensity of the resistance effect in video tracking, but sufficiently replicated experiments resulted in similar conclusions as EPG recordings and aphid population assays. One video tracking platform could screen 100 samples in parallel. Conclusions: Automated video tracking can be used to screen large plant populations for resistance to aphids and other piercing-sucking insects.
    Effects of supplementation level and particle size of alfalfa hay on growth characteristics and rumen development in dairy calves
    Mirzaei, M. ; Khorvash, M. ; Ghorbani, G.R. ; Kazemi-Bonchenari, M. ; Riasi, A. ; Nabipour, A. ; Borne, J.J.G.C. van den - \ 2015
    Journal of Animal Physiology and Animal Nutrition 99 (2015)3. - ISSN 0931-2439 - p. 553 - 564.
    neutral detergent fiber - early-weaned calf - feeding-behavior - holstein calves - sodium-butyrate - milk-production - early lactation - acid production - physical form - food-intake
    The aim of this study was to assess the effects of particle size (PS) of alfalfa hay on growth characteristics and rumen development in dairy calves at two levels of alfalfa supplementation. Fifty newborn dairy calves (42.7 ± 2.2 kg BW) were used in a 2 × 2 factorial arrangement with the factors supplementation level (low, 8%; or high, 16% on DM basis) and PS (medium, 2.92 mm; or long, 5.04 mm as geometrical means) of alfalfa hay. In addition, a control group without alfalfa hay was used. Hence, treatments were: control (C); low level with medium PS (LM); low level with long PS (LL); high level with medium PS (HM) or high level with long PS (HL). Growth performance of alfalfa-fed calves did not differ from control calves, but alfalfa supplementation decreased corneum thickness of the rumen wall. In alfalfa-fed calves, post-weaning starter intake was greater for LL calves than for LM calves. During the entire rearing period, starter intake was 26–32% higher for LL and HM calves than for LM calves. Pre-weaning average daily gain was higher for LL and HM calves than for HL calves, but this effect was not persistent over the entire rearing period. Final body weight decreased from 86 to 79 kg when the level of long PS alfalfa hay increased from 8 to 16%, but increased from 78 to 87 kg when the level of medium PS alfalfa increased from 8 to 16%. Regardless of PS and level, morphometric characteristics of rumen wall were generally similar among alfalfa feeding groups, but corneum thickness decreased from 8.7 to 6.1 µm with greater PS at the low level. These results indicate that adequate, but not excessive, physical stimulation is required for appropriate rumen development and growth performance of dairy calves.
    Diet selection of goats depends on season: roles of plant physical and chemical traits
    Mkhize, N.R. ; Scogings, P.F. ; Nsahlai, I.V. ; Dziba, L.E. - \ 2014
    African Journal of Range and Forage Science 31 (2014)3. - ISSN 1022-0119 - p. 209 - 214.
    south-african savanna - woody-plants - intake rates - subtropical savanna - browsing ruminants - feeding-behavior - semiarid savanna - capra-hircus - nguni goats - chemistry
    This paper reports on diet selection of goats offered six browse species (i.e. Acacia natalitia [Vachellia natalitia], Acacia nilotica [Vachellia nilotica], Dichrostachys cinerea, Grewia occidentalis, Gymnosporia maranguensis and Scutia myrtina) commonly found in moist Zululand thornveld. The hypotheses tested were: (1) plant species and season affect diet selection, (2) physical traits such as leaf phenology, spinescence, shoot morphology and leaf size affect selection, and (3) selection is related to tannins, fibre and protein in ways that indicate nutrient maximisation. Six 2-year-old castrated indigenous goats weighing an average of 26 kg each were individually penned and maintained on a basal diet of pellets and grass hay. Six branches were offered simultaneously to individual goats and intake per branch recorded and used as an index for diet selection. Diet selection was significantly influenced by interactions between plant species and season. Scutia myrtina and Grewia occidentalis were consistently the most preferred species, whereas Gynmosporia maranguensis and Acacia nilotica were least preferred throughout the seasons. Goats preferred broad-leaf and long-shoot species over fine-leaf and short-shoot species across all seasons. These results suggest that short-term diet selection in subhumid areas is not as strongly influenced by leaf phenology and plant chemistry as in semi-arid savannas.
    Normal adult survival but reduced Bemisia tabaci oviposition rate on tomato lines carrying an introgression from S. habrochaites
    Lucatti, A.F. ; Meijer-Dekens, R.G. ; Mumm, R. ; Visser, R.G.F. ; Vosman, B.J. ; Heusden, A.W. van - \ 2014
    BMC Genetics 15 (2014). - ISSN 1471-2156 - 23 p.
    nematode-resistance gene - hirsutum-f-glabratum - whitefly trialeurodes-vaporariorum - mediated insect resistance - wild tomato - lycopersicon-pennellii - glandular trichomes - feeding-behavior - potato aphid - qtl analysis
    Background Host plant resistance has been proposed as one of the most promising approaches in whitefly management. Already in 1995 two quantitative trait loci (Tv-1 and Tv-2) originating from S. habrochaites CGN1.1561 were identified that reduced the oviposition rate of the greenhouse whitefly (Trialeurodes vaporariorum). After this first study, several others identified QTLs affecting whitefly biology as well. Generally, the QTLs affecting oviposition were highly correlated with a reduction in whitefly survival and the presence of high densities of glandular trichomes type IV. The aim of our study was to further characterize Tv-1 and Tv-2, and to determine their role in resistance against Bemisia tabaci. Results We selected F2 plants homozygous for the Tv-1 and Tv-2 QTL regions and did three successive backcrosses without phenotypic selection. Twenty-three F2BC3 plants were phenotyped for whitefly resistance and differences were found in oviposition rate of B. tabaci. The F2BC3 plants with the lowest oviposition rate had an introgression on Chromosome 5 in common. Further F2BC4, F2BC4S1 and F2BC4S2 families were developed, genotyped and phenotyped for adult survival, oviposition rate and trichome type and density. It was possible to confirm that an introgression on top of Chr. 5 (OR-5), between the markers rs-2009 and rs-7551, was responsible for reducing whitefly oviposition rate. Conclusion We found a region of 3.06 Mbp at the top of Chr. 5 (OR-5) associated with a reduction in the oviposition rate of B. tabaci. This reduction was independent of the presence of the QTLs Tv- 1 and Tv-2 as well as of the presence of trichomes type IV. The OR-5 locus will provide new opportunities for resistance breeding against whiteflies, which is especially relevant in greenhouse cultivation.
    What do calves choose to eat and how do preferences affect calf behaviour and welfare?
    Webb, L.E. ; Engel, B. ; Berends, H. ; Reenen, C.G. van; Gerrits, W.J.J. ; Boer, I.J.M. de; Bokkers, E.A.M. - \ 2014
    Applied Animal Behaviour Science 161 (2014). - ISSN 0168-1591 - p. 7 - 19.
    ad-libitum milk - veal calves - dairy calves - feeding-behavior - animal-welfare - play-behavior - nonnutritive sucking - rumen development - food preference - roughage source
    Calves raised for milk or meat are fed diets that differ from feral-herd calf diets and are based on the nutritional requirements of the ‘average calf’. These diets may not meet the dietary preferences of each individual calf. This study explored diet preferences in calves with free dietary choice, and the effect of these preferences on behaviour. Group-housed Holstein-Friesian bull calves (N = 23) were given unlimited access to five diet components (i.e. milk replacer [MR], concentrate, maize silage, long hay and long barley straw). At 3 and 6 months of age, calves were moved for 7 days to an automated test pen in groups of four, where intake, time spent eating, and visit frequency to each diet component was recorded to assess preferences. Behaviour was recorded on 2 of the 7 days in the test pen, from 07:30 to 18:00 h using instantaneous scan sampling for periods of 30 min every 2.5 h at a 2 min interval. Solid feed intake at 6 months averaged 3205.5 ± 174.6 g DM d-1. At 3 months, calves selected the following proportion (average of individual proportions) of MR, concentrate and roughage in relation to total g DM intake: 51.6 ± 5.0%, 25.0 ± 4.7% and 23.4 ± 2.8%. At 6 months, the calves conserved the roughage proportion (23.3 ± 1.6%), but increased concentrate intake (47.1 ± 2.1%) at the expense of MR (29.6 ± 1.9%). Order of preference for the five diet components varied according to whether intake, time spent eating each component, or visit frequency was considered. On the whole, MR was preferred followed by concentrate and hay at both ages. Offering a dietary choice led to large individual variation in intake and to 47–80% calves having the same ranking as the average ranking for diet components. This suggests diets based on the ‘average calf’ may meet only few calves’ dietary preferences. Different variables showed different preference rankings and studies in the future should consider the relative importance of these variables in assessing animal preferences. Keywords: Behaviour, Dietary preference, Holstein-Friesian calves, Milk replacer, Solid feed, Welfare
    Improved acceptance of Chromonaela odorata by goat kids after weaning is caused by in utero exposure during late but not early pregnancy
    Hai, P.V. ; Schonewille, J.T. ; Tien, D.V. ; Everts, H. ; Hendriks, W.H. - \ 2014
    Applied Animal Behaviour Science 159 (2014). - ISSN 0168-1591 - p. 50 - 54.
    feeding-behavior - fetal sheep - chromolaena-odorata - food preference - amniotic-fluid - maternal diet - milk - consumption - fetus - rat
    The aim of the current experiment was to study the effect of the phase of pregnancy on in utero learning of Chromonaela odorata by the goat kids by comparing mid pregnancy (day 50–99, MP) with late pregnancy (day 100–145, LP). It was hypothesized that kids born to dams fed C. odorata during late pregnancy (day 100–145) would show an improved post-weaning consumption of this plant. Twenty four female goats (Co breed) were synchronized, inseminated and divided randomly into 4 equal groups. All pregnant goats were fed a diet either without (control) or with 50 g of C. odorata leave meal (COLM) at 10:00 am during 30 min during mid and late pregnancy. The COLM diet was fed either from 50 to 99 days of pregnancy (mid pregnancy, MP), or from 100 to 145 days of pregnancy (late pregnancy, LP) or from 50 to 145 days of pregnancy (MLP, positive control). After weaning (3 months old), one kid from each goat dam was selected to measure COLM intake for 30 min over a 4-week period. Feeding activities of the individually housed goat kids were monitored with a camera system. Post-weaning consumptions of COLM by the goat kids increased significantly (P <0.05) in the LP and MLP treatments and remained essentially unchanged in the control and MP treatments. The higher consumption of COLM by kids from the LP and MLP treatment was associated with a significantly (P <0.05) shorter latency to eat and a longer chewing time (P <0.05). It was concluded that transmission of feeding behaviour from mother to offspring occurs between day 100 to 145 of gestation and that it remains present at least 3 months after weaning in goats
    Rearing history affects behaviour and performance of two virulent Nasonovia ribisnigri populations on two lettuce cultivars
    Broeke, C.J.M. ten; Dicke, M. ; Loon, J.J.A. van - \ 2014
    Entomologia Experimentalis et Applicata 151 (2014)2. - ISSN 0013-8703 - p. 97 - 105.
    nematode meloidogyne-incognita - myzus-persicae hemiptera - host-plant resistance - feeding-behavior - tissue localization - aphid resistance - clones - gene - homoptera - biotypes
    Many aphid species have become virulent to host-plant resistance, which limits the sustainability of insect resistance breeding. However, when this adaptation to resistant plants is associated with fitness costs for the aphids, virulence can be lost in the absence of resistant plants. For two populations of the lettuce aphid, Nasonovia ribisnigri (Mosely) (Hemiptera: Aphididae), we evaluated whether virulence to Nr-gene-based resistance was lost on a susceptible lettuce, Lactuca sativa L. (Asteraceae), and assessed possible costs of virulence. The feeding behaviour and performance of these aphids, reared and tested on susceptible and resistant lettuce, were investigated. The rearing plant affected feeding behaviour and performance of the aphids. Temporary reduction and long-term loss of virulence were found. The total duration of phloem intake was shorter after being reared on susceptible lettuce and tested on resistant lettuce. In addition, one population had a lower survival on resistant lettuce after being reared on susceptible lettuce. There were also indications of fitness costs of the virulence in both populations.
    The Sum of lts Parts-Effects of Gastric Distention, Nutrient Content and Sensory Stimulation on Brain Activation
    Spetter, M.S. ; Graaf, C. de; Mars, M. ; Viergever, M.A. ; Smeets, P.A.M. - \ 2014
    PLoS ONE 9 (2014)3. - ISSN 1932-6203 - 10 p.
    body-weight regulation - food-intake - feeding-behavior - eating behavior - human amygdala - appetite - humans - satiety - taste - fat
    During food consumption the brain integrates multiple interrelated neural and hormonal signals involved in the regulation of food intake. Factors influencing the decision to stop eating include the foods' sensory properties, macronutrient content, and volume, which in turn affect gastric distention and appetite hormone responses. So far, the contributions of gastric distention and oral stimulation by food on brain activation have not been studied. The primary objective of this study was to assess the effect of gastric distention with an intra-gastric load and the additional effect of oral stimulation on brain activity after food administration. Our secondary objective was to study the correlations between hormone responses and appetite-related ratings and brain activation. Fourteen men completed three functional magnetic resonance imaging sessions during which they either received a naso-gastric infusion of water (stomach distention), naso-gastric infusion of chocolate milk (stomach distention + nutrients), or ingested chocolate-milk (stomach distention + nutrients + oral exposure). Appetite ratings and blood parameters were measured at several time points. During gastric infusion, brain activation was observed in the midbrain, amygdala, hypothalamus, and hippocampus for both chocolate milk and water, i.e., irrespective of nutrient content. The thalamus, amygdala, putamen and precuneus were activated more after ingestion than after gastric infusion of chocolate milk, whereas infusion evoked greater activation in the hippocampus and anterior cingulate. Moreover, areas involved in gustation and reward were activated more after oral stimulation. Only insulin responses following naso-gastric infusion of chocolate milk correlated with brain activation, namely in the putamen and insula. In conclusion, we show that normal (oral) food ingestion evokes greater activation than gastric infusion in stomach distention and food intake-related brain areas. This provides neural evidence for the importance of sensory stimulation in the process of satiation.
    Improved acceptance of Chromonaela odorata by goat kids after weaning is triggered by in utero exposure but nog consumption of milk
    Hai, P.V. ; Schonewille, J.T. ; Tien, D.V. ; Everts, H. ; Hendriks, W.H. - \ 2013
    Applied Animal Behaviour Science 146 (2013). - ISSN 0168-1591 - p. 66 - 71.
    chromolaena-odorata - feeding-behavior - food preference - amniotic-fluid - maternal diet - tropical weed - pregnant ewes - fetal - sheep - taste
    The aim of the current study was to determine whether the improved post-weaning intake of Chromonaela odorata by goat kids is related to either the in utero period of the goat kids or the subsequent suckling period. It was hypothesized that kids born to dams fed C. odorata during pregnancy and receiving milk from dams not exposed to C. odorata during pregnancy show an improved acceptance to consume this plant. Twenty female goats were successfully synchronized and divided into 4 groups. Two groups (1 and 3) were offered 50 g of dried C. odorata leave meal (COLM) mixed with a basic diet for the last 3 months of pregnancy until 1 week before parturition. At birth the kids from the goats in group 1 and 2 were cross fostered without colostrum or milk from their own mother. While waiting for the delivery of kid from another goat, the kid was fed milk replacer or milk from any goat dam in the same treatment. Kids from groups 3 and 4 remained with their mothers. After weaning (2.5 months old), one kid from each goat dam was selected for COLM intake which was measured for 30 min over a 4 week period. Feeding activities of the individually housed goat kids was monitored with a camera system. Kids born to dams receiving COLM during pregnancy consumed higher amounts of the COLM supplemented test feed during all feeding preference tests compared to kids from the control group, particularly during week 3 and 4 (P <0.001). Shorter latency, longer time spent on each meal and total eating time, chewing time and higher meal size (P <0.05) were different in the kids born from does that ingested COLM during pregnancy. It is concluded that prenatal exposure to C. odorata via maternal ingestion significantly increases the intake of C. odorata by weaned goat kids. This improved intake is due to the in utero learning and not the transfer of (secondary) components via the milk of the mothers fed C. odorata during pregnancy.
    Walking with insects. Molecular mechanisms behind parasitic manipulation of host behaviour
    Houte, S. van; Ros, V.I.D. ; Oers, M.M. van - \ 2013
    Molecular Ecology 22 (2013)13. - ISSN 0962-1083 - p. 3458 - 3475.
    dependent protein-kinase - tachykinin-related peptides - wasp cotesia-congregata - water-seeking behavior - feeding-behavior - locomotor-activity - neuropeptide-y - natural variation - altered behavior - dicrocoelium-dendriticum
    Parasitic infections are often followed by changes in host behaviour. Numerous and exquisite examples of such behavioural alterations are known, covering a broad spectrum of parasites and hosts. Most descriptions of such parasite-induced changes in host behaviour are observational reports, while experimentally confirmed examples of parasite genes inducing these changes are limited. In this study, we review changes in invertebrate host behaviour observed upon infection by parasites and discuss such changes in an evolutionary context. We then explore possible mechanisms involved in parasite-induced changes in host behaviour. Genes and pathways known to play a role in invertebrate behaviour are reviewed, and we hypothesize how parasites (may) affect these pathways. This review provides the state of the art in this exciting, interdisciplinary field by exploring possible pathways triggered in hosts, suggesting methodologies to unravel the molecular mechanisms that lead to changes in host behaviour.
    Identification and QTL mapping of whitefly resistance components in Solanum galapagense
    Firdaus, S. ; Heusden, A.W. van; Hidayati, N. ; Supena, E.D.J. ; Mumm, R. ; Vos, R.C.H. de; Visser, R.G.F. ; Vosman, B. - \ 2013
    Theoretical and Applied Genetics 126 (2013)6. - ISSN 0040-5752 - p. 1487 - 1501.
    hirsutum f-glabratum - bemisia-tabaci - lycopersicon-pennellii - wild tomato - glandular trichomes - frankliniella-occidentalis - feeding-behavior - pest resistance - biotype-b - aleyrodidae
    Solanum galapagense is closely related to the cultivated tomato and can show a very good resistance towards whitefly. A segregating population resulting from a cross between the cultivated tomato and a whitefly resistant S. galapagense was created and used for mapping whitefly resistance and related traits, which made it possible to study the genetic basis of the resistance. Quantitative trait loci (QTL) for adult survival co-localized with type IV trichome characteristics (presence, density, gland longevity and gland size). A major QTL (Wf-1) was found for adult survival and trichome characters on Chromosome 2. This QTL explained 54.1 % of the variation in adult survival and 81.5 % of the occurrence of type IV trichomes. A minor QTL (Wf-2) for adult survival and trichome characters was identified on Chromosome 9. The major QTL was confirmed in F3 populations. Comprehensive metabolomics, based on GCMS profiling, revealed that 16 metabolites segregating in the F2 mapping population were associated with Wf-1 and/or Wf-2. Analysis of the 10 most resistant and susceptible F2 genotypes by LCMS showed that several acyl sugars were present in significantly higher concentration in the whitefly resistant genotypes, suggesting a role for these components in the resistance as well. Our results show that whitefly resistance in S. galapagense seems to inherit relatively simple compared to whitefly resistance from other sources and this offers great prospects for resistance breeding as well as elucidating the underlying molecular mechanism(s) of the resistance.
    High throughput phenotyping for aphid resistance in large plant collections
    Chen, X. ; Vosman, B. ; Visser, R.G.F. ; Vlugt, R.A.A. van der; Broekgaarden, C. - \ 2012
    Plant Methods 8 (2012). - ISSN 1746-4811
    cauliflower mosaic-virus - yellow dwarf virus - leaf-curl-virus - arabidopsis-thaliana - glucosinolate accumulation - feeding-behavior - myzus-persicae - bemisia-tabaci - green peach - helicoverpa-armigera
    Background: Phloem-feeding insects are among the most devastating pests worldwide. They not only cause damage by feeding from the phloem, thereby depleting the plant from photo-assimilates, but also by vectoring viruses. Until now, the main way to prevent such problems is the frequent use of insecticides. Applying resistant varieties would be a more environmental friendly and sustainable solution. For this, resistant sources need to be identified first. Up to now there were no methods suitable for high throughput phenotyping of plant germplasm to identify sources of resistance towards phloem-feeding insects. Results: In this paper we present a high throughput screening system to identify plants with an increased resistance against aphids. Its versatility is demonstrated using an Arabidopsis thaliana activation tag mutant line collection. This system consists of the green peach aphid Myzus persicae (Sulzer) and the circulative virus Turnip yellows virus (TuYV). In an initial screening, with one plant representing one mutant line, 13 virus-free mutant lines were identified by ELISA. Using seeds produced from these lines, the putative candidates were re-evaluated and characterized, resulting in nine lines with increased resistance towards the aphid. Conclusions: This M. persicae-TuYV screening system is an efficient, reliable and quick procedure to identify among thousands of mutated lines those resistant to aphids. In our study, nine mutant lines with increased resistance against the aphid were selected among 5160 mutant lines in just 5 months by one person. The system can be extended to other phloem-feeding insects and circulative viruses to identify insect resistant sources from several collections, including for example genebanks and artificially prepared mutant collections.
    An assessment of the current and potential future natural and anthropogenic issues facing migratory shorebirds
    Sutherland, W.J. ; Alves, J.A. ; Chang, C.H. ; Davidson, D.C. ; Finlayson, C.M. ; Gill, J.A. ; Gill, R.E. ; González, P.M. ; Gunnarsson, T.G. ; Kleijn, D. ; Spray, C.J. ; Szekely, T. ; Thompson, D.B.A. - \ 2012
    Ibis 154 (2012)4. - ISSN 0019-1019 - p. 663 - 679.
    estuary west portugal - harmful algal blooms - climate-change - wader populations - macroalgal blooms - land-use - pluvialis-apricaria - ocean acidification - feeding-behavior - changing climate
    We review the conservation issues facing migratory shorebird populations that breed in temperate regions and use wetlands in the non-breeding season. Shorebirds are excellent model organisms for understanding ecological, behavioural and evolutionary processes and are often used as indicators of wetland health. A global team of experienced shorebird researchers identified 45 issues facing these shorebird populations, and divided them into three categories (natural, current anthropogenic and future issues). The natural issues included megatsunamis, volcanoes and regional climate changes, while current anthropogenic threats encompassed agricultural intensification, conversion of tidal flats and coastal wetlands by human infrastructure developments and eutrophication of coastal systems. Possible future threats to shorebirds include microplastics, new means of recreation and infectious diseases. We suggest that this review process be broadened to other taxa to aid the identification and ranking of current and future conservation actions.
    EPG monitoring of the probing behaviour of the common brown leafhopper Orosius orientalis on artificial diet and selected host plants
    Trebicki, P. ; Tjallingii, W.F. ; Harding, R.M. ; Rodoni, B.C. ; Powell, K.S. - \ 2012
    Arthropod-Plant Interactions 6 (2012)3. - ISSN 1872-8855 - p. 405 - 415.
    electrical penetration graphs - susceptible rice varieties - feeding-behavior - nilaparvata-lugens - southeastern australia - stylet penetration - xylella-fastidiosa - fine-structure - nymphal stages - aphids
    The common brown leafhopper Orosius orientalis (Hemiptera: Cicadellidae) is a polyphagous vector of a range of economically important pathogens, including phytoplasmas and viruses, which infect a diverse range of crops. Studies on the plant penetration behaviour by O. orientalis were conducted using the electrical penetration graph (EPG) technique to assist in the characterisation of pathogen acquisition and transmission. EPG waveforms representing different probing activities were acquired from adult O. orientalis probing in planta, using two host species, tobacco Nicotiana tabacum and bean Phaseolus vulgaris, and in vitro using a simple sucrose-based artificial diet. Five waveforms (O1–O5) were evident when O. orientalis fed on bean, whereas only four waveforms (O1–O4) and three waveforms (O1–O3) were observed when the leafhopper fed on tobacco and on the artificial diet, respectively. Both the mean duration of each waveform and waveform type differed markedly depending on the food substrate. Waveform O4 was not observed on the artificial diet and occurred relatively rarely on tobacco plants when compared with bean plants. Waveform O5 was only observed with leafhoppers probing on beans. The attributes of the waveforms and comparative analyses with previously published Hemipteran data are presented and discussed, but further characterisation studies will be needed to confirm our suggestions.
    EPG waveform characteristics of solenopsis mealybug stylet penetration on cotton
    Huang, F. ; Tjallingii, W.F. ; Zhang, P. ; Zhang, J. ; Lu, Y. ; Lin, J. - \ 2012
    Entomologia Experimentalis et Applicata 143 (2012)1. - ISSN 0013-8703 - p. 47 - 54.
    manihoti matile-ferrero - feeding-behavior - cassava mealybug - phenacoccus-solenopsis - host plants - hemiptera pseudococcidae - circulifer-tenellus - beet leafhopper - homoptera - ultrastructure
    The solenopsis mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae), is a polyphagous insect known to cause severe damage to cotton (especially transgenic varieties) in South Asia, and currently poses a serious threat in Asia and potentially elsewhere. Stylet penetration behavior of P. solenopsis on cotton was monitored using the electrical penetration graph (EPG) technique (DC system) and the EPG characteristics were compared with those previously published from Phenacoccus manihoti Matile-Ferrero and Planococcus citri (Risso). We identified and further characterized typical waveforms of A, B, C, and pd (together pathway), E1 and E2 (phloem), F (derailed stylet mechanics), and G (xylem). Five novel EPG aspects were distinguished in the EPG waveforms from P. solenopsis: (1) obvious B waveforms occurred following waveform A, (2) during waveform C, some aphid-like E1e waveforms were observed, (3) prolonged potential drops (pd) up to >1 h occurred with two continuously alternating sub-phases pd1 and pd2, (4) the pd1 waveform always occurred as the first waveform related to phloem sieve elements, preceding the other phloem waveforms (E), the labeling of which we changed to achieve a better comparison to the aphid E waveforms, and (5) waveform F, related to derailed stylet mechanics occurred but was not reported from other mealybugs so far. This is mainly a waveform morphology study to extend existing knowledge on mealybug EPGs to investigate mealybug-host plant interactions. Further experimental verification of waveform correlations with plant tissue positions of stylet tips and insect activities is still needed.
    Dietary overlap between the potential competitors herring, sprat and anchovy in the North Sea
    Raab, K.E. ; Nagelkerke, L.A.J. ; Boeree, C. ; Rijnsdorp, A.D. ; Temming, A. ; Dickey-Collas, M. - \ 2012
    Marine Ecology Progress Series 470 (2012). - ISSN 0171-8630 - p. 101 - 111.
    engraulis-encrasicolus l. - central baltic sea - clupea-harengus - feeding-behavior - intraguild predation - trophic interactions - population-dynamics - mediterranean sea - fish eggs - irish sea
    European anchovy Engraulis encrasicolus increased its abundance and distribution in the North Sea during the mid-1990s and may consume similar zooplankton to and/or compete with other occupants of the North Sea like herring Clupea harengus and sprat Sprattus sprattus. The diets of adult anchovy, sprat and juvenile herring of comparable sizes, sampled close in time and space, were compared to understand how the 3 species prey on zooplankton and establish whether their diets overlap or not. Anchovy was found to be more generalist, consuming a higher diversity of prey items. Herring was more specialized, with low diversity of food items. Sprat was intermediate between anchovy and herring. The dietary overlap between anchovy and sprat was highest, followed by herring and sprat before anchovy and herring. The mean weight of stomach contents did not differ between species. We conclude that of the 3 species, anchovy is likely to be the least affected by changing plankton communities.
    Protein Tyrosine Phosphatase-Induced Hyperactivity Is a Conserved Strategy of a Subset of BaculoViruses to Manipulate Lepidopteran Host Behavior
    Houte, S. van; Ros, V.I.D. ; Mastenbroek, T.G. ; Vendrig, N.J. ; Hoover, K. ; Spitzen, J. ; Oers, M.M. van - \ 2012
    PLoS ONE 7 (2012)10. - ISSN 1932-6203 - 11 p.
    nuclear polyhedrosis-virus - spodoptera-exigua larvae - rna 5'-triphosphatase - feeding-behavior - aedes-aegypti - gene - impact - transmission - infection - silkworm
    Many parasites manipulate host behavior to increase the probability of transmission. To date, direct evidence for parasitic genes underlying such behavioral manipulations is scarce. Here we show that the baculovirus Autographa californica nuclear polyhedrovirus (AcMNPV) induces hyperactive behavior in Spodoptera exigua larvae at three days after infection. Furthermore, we identify the viral protein tyrosine phosphatase (ptp) gene as a key player in the induction of hyperactivity in larvae, and show that mutating the catalytic site of the encoded phosphatase enzyme prevents this induced behavior. Phylogenetic inference points at a lepidopteran origin of the ptp gene and shows that this gene is well-conserved in a group of related baculoviruses. Our study suggests that ptp-induced behavioral manipulation is an evolutionarily conserved strategy of this group of baculoviruses to enhance virus transmission, and represents an example of the extended phenotype concept. Overall, these data provide a firm base for a deeper understanding of the mechanisms behind baculovirus-induced insect behavior.
    Resistance to Bemisia tabaci in tomato wild relatives
    Firdaus, S. ; Heusden, A.W. van; Hidayati, N. ; Supena, E.D.J. ; Visser, R.G.F. ; Vosman, B. - \ 2012
    Euphytica 187 (2012)1. - ISSN 0014-2336 - p. 31 - 45.
    hirsutum-f-glabratum - whitefly trialeurodes-vaporariorum - lycopersicon-hirsutum - argentifolii homoptera - population-dynamics - glandular trichomes - insect-resistance - spodoptera-exigua - feeding-behavior - pest resistance
    Bemisia tabaci is one of the most threatening pests in agriculture, particularly in Solanaceous crops such as tomato and pepper that are cultivated in the open field. Pesticide application is often not effective and hazardous to humans and environment. The exploitation of plant natural defenses that are present in wild relatives of tomato, may offer a solution. To evaluate resistance parameters and to identify plant material with high levels of resistance, we screened a number of accessions of tomato wild relatives using three methods; a free-choice test in a screenhouse in Indonesia, a no-choice test with clip-on cages in a greenhouse and a leaf disc test in a climate-room in the Netherlands. Antibiosis resulting in low adult survival was the major component for resistance in tomato. However, other resistance component(s) may play a role as well. In some accessions there was a change in the resistance level over time. Several resistance parameters used in the different tests were well correlated. The best resistance source was an accession of Solanum galapagense, which had not been identified as being resistant in the past. This is of particular interest as this species is closely related to the cultivated tomato, which may facilitate introgression of the resistance component(s). Whitefly non-preference and resistance were associated with the presence of type IV trichomes. Other mechanisms might be involved since some accessions without type IV trichomes showed low nymphal density. The leaf disc test is a good in vitro alternative for the clip-on cage whitefly resistance screening, as shown by the high correlation between the results obtained with this test and the clip-on cage test. This offers breeders the possibility to carry out tests more efficiently
    Stylet penetration of Cacopsylla pyri; an electrical penetration graph (EPG) study
    Civolani, S. ; Leis, M. ; Grandi, G. ; Garzo, E. ; Pasqualini, E. ; Musacchi, S. ; Chicca, M. ; Castaldelli, G. ; Rossie, M. ; Tjallingii, W.F. - \ 2011
    Journal of Insect Physiology 57 (2011)10. - ISSN 0022-1910 - p. 1407 - 1419.
    candidatus phytoplasma mali - form pear psylla - feeding-behavior - aphid stylets - apple proliferation - fine-structure - decline - host - homoptera - ingestion
    Detailed information on plant penetration activities by pear psylla Cacopsylla pyri L. (Hemiptera Psyllidae) is essential to study phytoplasma transmission of “Candidatus Phytoplasma pyri” responsible of pear decline disease (PD) and to trace and evaluate resistant traits in new pear tree selections for advanced breeding programs. The electrical penetration graph technique or (full) EPG may relevantly contribute to this knowledge. C. pyri EPG waveforms were characterized on basis of amplitude, frequency, voltage level, and electrical origin. Additionally, stylet tracks and the putative location of stylet tips in the plant tissue were histologically related to EPG waveforms by light and transmission electron microscopy observations after stylectomy. More than one waveform occurred in the same tissue: PA, PB, PC1 and PC2 were all detected in the mesophyll, and PE1 and PE2 were both recorded in the phloem. Waveform PE1 was always preceded by transient waveform PD, as previously described in other psyllids. Interestingly, no brief intracellular punctures (potential drop waveforms) were observed during plant penetration, opposite of what is usually recorded in aphids and other Sternorrhyncha.
    Effects of an anionic surfactant (FFD-6) on the energy and information flow between a primary producer (Scenedesmus obliquus) and a consumer (Daphnia magna)
    Lürling, M.F.L.L.W. ; Lange, H.J. de; Peeters, E.T.H.M. - \ 2011
    Ecotoxicology 20 (2011)8. - ISSN 0963-9292 - p. 1881 - 1889.
    absolute-configuration determination - unicell-colony transformation - alkylbenzene sulfonate las - aliphatic sulfates - morphological defense - phenotypic plasticity - aquatic toxicity - feeding-behavior - risk-assessment - phytoplankton
    The effects of a commercially available anionic surfactant solution (FFD-6) on growth and morphology of a common green alga (Scenedesmus obliquus) and on survival and clearance rates of the water flea Daphnia magna were studied. The surfactant-solution elicited a morphological response (formation of colonies) in Scenedesmus at concentrations of 10-100 µl l(-1) that were far below the No Observed Effect Concentration (NOEC) value of 1,000 µl l(-1) for growth inhibition. The NOEC-value of FFD-6 for colony-induction was 3 µl l(-1). Daphnia survival was strongly affected by FFD-6, yielding LC(50-24h) and LC(50-48h) of 148 and 26 µl l(-1), respectively. In addition, clearance rates of Daphnia feeding on unicellular Scenedesmus were inhibited by FFD-6, yielding a 50% inhibition (EC(50-1.5h)) at 5.2 µl l(-1) with a NOEC of 0.5 µl l(-1). When Daphnia were offered FFD-6-induced food in which eight-celled colonies (43 × 29 µm) were most abundant, clearance rates (~0.14 ml ind.(-1) h(-1)) were only 25% the rates of animals that were offered non-induced unicellular (15 × 5 µm) Scenedesmus (~0.56 ml ind.(-1) h(-1)). As FFD-6 concentrations in the treated food used in the experiments were far below the NOEC for clearance rate inhibition, it is concluded that the feeding rate depression was caused by the altered morphology of the Scenedesmus moving them out of the feeding window of the daphnids. The surfactant evoked a response in Scenedesmus that is similar to the natural chemically induced defensive reaction against grazers and could disrupt the natural information conveyance between these plankton organisms
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