bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of soil incorporation on the efficacy of the rhabditid nematode, Phasmarhabditis hermaphrodita, as a biological control agent for slugs
Authors: WILSON M J. , HUGHES L A. , HAMACHER G M. , BARAHONA L D. , GLEN D M. 
Published: February 2008

SummaryThe effects of soil cultivation immediately after application of the rhabditid nematode, Phasmarhabditis hermaphrodita, to the soil surface were investigated in two field experiments. The first experiment was done in mini‐plots separated by barriers, with an artificially introduced population of slugs (Deroceras reticulatum). Nematodes were applied as a drench at a rate of 3 times 109 ha‐1 in one of two application volumes and then left undisturbed or incorporated into the soil by cultivation to 2 cm or 10 cm depth. Moist soil conditions were maintained by irrigation throughout the experiment. Nematode application significantly reduced slug damage to Chinese cabbage seedlings throughout the 7 wk duration of the experiment and the population of D. reticulatum in soil 7 wk after treatment. However, soil cultivation had no effect and did not interact with the effect of nematodes. In the second experiment, in a crop of winter wheat, nematodes were applied to soil by hand‐lance at a rate of 3 times 109 ha‐1 and left undisturbed on the soil surface or incorporated by spring‐tine cultivation to a depth of 2, 5 or 10 cm. In this experiment, nematodes were applied to dry soil. Cultivation alone had no effect. Nematode application reduced slug damage to wheat plants in plots where nematodes were incorporated into the soil, but not where they were left on the surface. There was no detectable impact of nematodes on slug populations in the wheat experiment.
Molecular ecology of some Cecidophyopsis mites (Acari: Eriophyidae) on Ribes species and evidence for their natural cross colonisation of blackcurrant (R. nigrum)
Authors: FENTON B. , JONES A T. , MALLOCH G. , THOMAS W P. 
Published: February 2008

SummaryRibosomal DNA from Cecidophyopsis mites from different Ribes species was amplified using the polymerase chain reaction and the products digested using restriction enzymes. After separating the DNA fragments on gels, it was possible to identify specimens of mites obtained from field samples by comparing the profiles of their DNA banding patterns with those of known Cecidophyopsis species. Using this analysis, a non‐gall forming mite found infesting blackcurrant buds in New Zealand was identified as the gooseberry mite (C. grossulariae). On wild red currant (Ribes spicatum) from Finland showing two sizes of galled buds, the red currant gall mite (C. selachodon) was identified in the larger galls located at the tips of branches and a distinct mite in the smaller galls located on the lower parts of the branches. A mite with a DNA banding profile indistinguishable from this latter mite from R. spicatum was also identified in galled buds of blackcurrant genotypes growing in Finland, including those containing the blackcurrant gall mite (C. n'ftw)‐resistance genes P or Ce. The DNA banding profile of this mite resembled most closely that of C. ribis, but was distinct from it. The occurrence of C. grossulariae and this distinct Cecidophyopsis mite on blackcurrant has implications for the genetic control of Cecidophyopsis mites and possibly for the spread of the reversion disease agent in this crop.
The effects of organic and conventional farming methods on plant bug densities (Hemiptera: Heteroptera) within winter wheat fields
Authors: MOREBY S J. 
Published: February 2008

SummaryAn understanding of the mechanisms responsible for direct and indirect effects of pesticides on Heteroptera were studied by comparing densities within fields of winter wheat on organically and conventionally managed farms. Weed and insect densities were estimated in 56 fields in 1990 and 62 in 1991. Four out of five of the heteropteran groups studied were more numerous within organic fields in both years, however differences were statistically significant in only one out of 10 comparisons. Differences in agricultural practices between the two farming regimes are given as possible reasons for the densities observed.
Genetic variation in Drechslera teres populations as indicated by RAPD markers
Authors: PELTONEN S. , JALLI M. , KAMMIOVIRTA K. , KARJALAINEN R. 
Published: February 2008

SummaryRandom amplified polymorphic DNA (RAPD) was used to assess genetic variation among 48 isolates of Drechslera teres originating from different sites in Finland. RAPD profiles were generated with five arbitrary 10‐mer primers and revealed polymorphisms suitable for screening differentiation in this fungal population. Using UPGMA clustering analysis, a similarity coefficient of approximately 63% was observed between all D. teres isolates studied. The variation was, however, distributed on a small scale as different genotypes were found from the same plant. The isolates could not be grouped according to geographic origin, aggressiveness, growth rate or morphological features, indicating that the primers used in this study were neutral markers for these characters. The primers were, however, able to differentiate between isolates of Helminthosporium species (D. teres, Drechslera graminea and Bipolaris sorokiniana).
Unusually severe symptoms are a characteristic of the current epidemic of mosaic virus disease of cassava in Uganda
Authors: GIBSON R W. , LEGG J P. , OTIM‐NAPE G W. 
Published: February 2008

SummaryMosaic disease (MD) is more severe in cassava plants infected within the area of the current epidemic in northern and central Uganda than to the south of the affected area. This difference in severity was recorded within a single cultivar as well as amongst the mixtures of cultivars found commonly in farmers' fields. An increase in severity also occurred as the epidemic passed through localities. Varietal or agroecological factors coincident with the area of the epidemic are therefore unlikely to cause the increased severity. The severe disease could also be graft and cutting transmitted and could super‐infect mildly diseased plants. Both mildly and severely diseased plants gave positive reactions in ELISA tests to antisera prepared against African cassava mosaic virus (ACMV) and an unusually severe form of ACMV or a closely related geminivirus is likely to be the cause of the severe mosaic disease. The epidemic also involves increased populations of the whitefly vector of ACMV, Bemisia tabaci, and possible hypotheses are presented as to how these phenomena may be related.
A novel luteovirus from sweet potato, sweet potato leaf speckling virus
Authors: FUENTES S. , MAYO M A. , JOLLY C A. , NAKANO M. , QUERCI M. , SALAZAR L F. 
Published: February 2008

SummaryA virus obtained from accession DLP 1541 of the International Potato Center (CIP) sweet potato germplasm collection was shown to induce a curling and a white speckling of the leaves of infected plants. We propose to name it sweet potato leaf speckling virus (SPLSV). It was found in samples from 15 of 77 accessions tested and also in samples from farms at Chiclayo and Trujillo in northern Peru. SPLSV was transmissible by grafting, but not mechanically, and was transmitted in a persistent manner by Macrosiphum euphorbiae but not by Myzus persicae, Aphis gossypii or whiteflies. Isometric particles were purified from infected plants by procedures designed to purify luteoviruses. Reverse transcription and polymerase chain reaction amplification of RNA from SPLSV‐infected plants using degenerate primers designed to amplify sequences either in luteovirus RNA or in potato leafroll virus (PLRV) RNA yielded c. 500 bp and c. 600 bp DNA fragments respectively. The nucleotide sequence of these fragments encoded two polypeptides characteristic in sequence of luteovirus proteins, which suggests that SPLSV should be classified in the genus Luteovirus. The amino acid sequence of the putative coat protein was 70% identical to that of PLRV. On the basis of the coat protein sequences, SPLSV is more similar to PLRV than is any other luteovirus. However, SPLSV particles did not react with antibodies to PLRV in ISEM or ELISA tests.
Weed performance in crop rotations with and without leys and at different nitrogen levels
Authors: ANDERSSON TORSTEN N. , MILBERG PER 
Published: February 2008

SummaryWeed populations were studied from a 26‐year‐old field experiment in southern Sweden with three different 6‐year crop rotations, each with four rates of nitrogen application. The rotations differed in that one had a two‐year legume‐grass ley, another had a two‐year grass ley, and that the third had spring wheat followed by a repeatedly harrowed fallow. The leys and the fallow were followed by turnip rape, winter wheat, oats and barley which was undersown in the two ley rotations. Data on weed biomass, collected in one season, were subjected to multivariate analysis.Winter turnip rape had the highest weed biomass. However, of the several weed species, only Matricaria perforata Merat was important in wheat (the crop following turnip rape in the rotation). The weed flora did not differ consistently between rotations. We conclude that none of the three rotations had developed any major weed problems under the past weed management regime (herbicides applied to cereal crops).There was no consistent effect of nitrogen fertilisation on total weed biomass in any of the three rotations. However, when comparing the weed floras in winter wheat, turnip rape and oats, the unfertilised plots differed from the plots receiving nitrogen. In the two latter crops, the abundant, low‐growing annual Stellaria media (L.) Vil. performed best in fertilised plots with dense stands. Equisetum arvense L., the most abundant perennial weed, was important only in unfertilised plots.
The influence of R:FR ratio on the growth, photosynthesis and rooting ability of Terminalia spinosa Engl. and Triplochiton scleroxylon K. Schum
Authors: NEWTON A C. , DICK J McP , McBEATH C. , LEAKEY R R B. 
Published: February 2008

SummaryStockplants of the tropical hardwoods Terminalia spinosa Engl, and Triplochiton scleroxylon K. Schum were grown in a controlled environment under red:far‐red (R:FR) ratios ranging from 0.5‐3.1. In both species, rates of shoot height increment were higher (P < 0.05) under the low R:FR ratios as a result of increased internode elongation. In Terminalia spinosa, specific leaf area (SLA) was also significantly higher under lower R:FR ratios, values ranging from 175 to 210 cm2 g‐1 in the 3.1 and 0.9 treatments respectively. No effect of R:FR ratio on SLA was recorded in Triplochiton scleroxylon. Pre‐severance photo‐synthetic rate, stomatal conductance and water‐use efficiency were increased under the higher R:FR ratios in Terminalia spinosa, rates of photosynthesis ranging between 2.68‐4.59 μmol m‐2 s‐1 in the 0.5 and 3.1 R:FR treatments respectively. Gas exchange rates of Triplochiton scleroxylon were unaffected by R:FR treatment. These contrasting responses to variation in R:FR ratio were associated with differences in rooting ability. In Terminalia spinosa, significantly higher percentage rooting was recorded in the cuttings from the 3.1 R:FR treatment than from 0.5, with values of 93.7% and 77.5% recorded respectively. R:FR ratio also affected rooting percentages of Triplochiton scleroxylon, but in this case, higher rooting percentages were recorded in the lower R:FR ratios, values ranging from 31.1–54.1% in the 3.0 and 0.5 R.FR treatments respectively. This difference in rooting response is attributed to the contrasting effects of R:FR ratio on the leaf and stem morphology of the two species. The implications of these results for stockplant management are discussed.
Identification of phytoplasmas associated with a decline of European hackberry (Celtis australis)
Authors: BERTACCINI A. , MITTEMPERGHER L. , VIBIO M. 
Published: February 2008

SummaryThe presence of phytoplasmas in declining trees of European hackberry was demonstrated for the first time using polymerase chain reaction assays with primers amplifying phytoplasma 16S rDNA regions. Restriction fragment length polymorphism analysis of these DNA fragments together with PCR, employing primers specific for particular phylogenetic groups of phytoplasmas, made it possible to detect the presence of aster yellows group (16SrI) related phytoplasmas. These were classified into two different subgroups (I‐B and I‐C) and were present in both symptomatic and asymptomatic hackberry plants. Aster yellows‐related phytoplasmas were found in all the root samples collected during the winter. In addition, phytoplasmas from the peach X disease group (16SrIH) were found in four out of 10 root samples; in five root samples phytoplasmas of the elm yellows group (16SrV) were also present.
Monoclonal antibodies for the detection and differentiation of faba bean necrotic yellows virus isolates
Authors: FRANZ A. , MAKKOUK K M , KATUL L. , VETTEN H J 
Published: February 2008

SummaryMurine monoclonal antibodies (MAbs) were produced for the detection of faba bean necrotic yellows virus (FBNYV), an isometric ssDNA virus belonging to a new, yet unnamed genus of plant viruses. A total of 19 FBNYV‐specific MAbs were obtained from three fusion experiments and characterised by determining their immunoglobulin types and titres as well as their corresponding epitopes. At least six distinct epitopes were revealed on FBNYV particles of different virus isolates. Only two MAbs reacted with SDS‐dissociated FBNYV virions in triple antibody sandwich (TAS)‐ELISA and with viral capsid protein in Western blots. Almost all MAbs were more sensitive in detecting FBNYV in viruliferous aphids by TAS‐ELISA than polyclonal anti‐FBNYV IgG by double antibody sandwich ELISA and permitted virus detection in individual aphids even following short acquisition access feeding periods.Coat protein variation among FBNYV isolates and serological relatedness to taxonomically similar viruses was studied by determining the cross reactivity of these MAbs with several field isolates of FBNYV as well as with milk vetch dwarf (MDV), banana bunchy top (BBTV), and subterranean clover stunt (SCSV) viruses. Whereas none of the MAbs reacted with BBTV, only one reacted with SCSV, indicating that FBNYV and SCSV share a common epitope. By contrast, 16 of the 19 MAbs reacted with MDV, suggesting that FBNYV and MDV are serologically closely related and strains of the same virus. When all 19 MAbs produced were tested against a total of 107 samples of FBNYV collected during virus surveys in Egypt, Ethiopia, Jordan, Morocco and Syria, five MAbs showed differential reactions. While the majority of the samples reacted with all 19 MAbs, about 20% of the 107 FBNYV samples did not react with one and/or other of these five MAbs, permitting the differentiation of seven serotypes of FBNYV and suggesting a considerable coat protein variation in FBNYV isolates from the countries surveyed. The MDV isolate from Japan and five FBNYV samples from Ethiopia appeared to be the least closely related to typical FBNYV isolates by not reacting with three and four, respectively, of the five differentiating Mabs.
Distribution and incidence of yellowing viruses in sugar beet crops in Spain from 1990 to 1993
Authors: ROMAN C PEREZ DE SAN , ORTIZ A. , AYALA J. 
Published: February 2008

SummarySurveys of the principal yellowing viruses of sugar beet, beet yellows virus (BYV) and beet mild yellowing virus (BMYV) in Spain were carried out from 1990–1993. Beet yellowing viruses were detected in all provinces, although the mean percentages of plants infected with BYV and BMYV were practically zero in the southern zone. Within the northern zone high variations from one province to another could be observed. The mean percentages of plants infected with BYV were higher in the Ebro Valley than in the Duero Valley. Areas infected with BYV were very restricted, while BMYV could be found to a variable extent all over Spain, although the infection levels were lower. The incidence and distribution of these viruses in the Spanish sugar beet crop makes the study and application of control measures for beet yellowing viruses necessary.
Viral twig necrosis of sweet cherry. Modes of transmission and spread of petunia asteroid mosaic virus (PeAMV)
Authors: PFEILSTETTER E. , KUNZE L. , ZINKERNAGEL V. 
Published: February 2008

SummaryGrafting symptomless scions, derived from petunia asteroid mosaic virus (PeAMV)‐infected trees, to healthy rootstocks resulted in only 3.3% infection in the resulting trees. Up to 90% of seeds from infected sweet cherries contained high quantities of PeAMV, but the virus was not transmitted to the seedlings apparently because of low virus content in the embryo and loss of infectivity during seed maturation and storage. Replanting healthy cherry trees cv. Sam, grafted to different rootstocks, into contaminated soils resulted in new infections. Eight of 13 trees on rootstocks derived from Prunus avium (F 12/1 and cv. Sam on its own roots) were infected with PeAMV within a period of four years but only one of 16 trees on Weiroot‐rootstocks (selections from Prunus cerasus) became infected. The detection of PeAMV in naturally contaminated soil samples by the bait plant procedure, using Nicotiana clevelandii, was superior to testing soil eluates by enzyme‐linked immunosorbent assay (ELISA) and immuno electron microscopy (IEM). Wild plants may contribute to virus propagation and maintenance of virus contamination of the soil as 25 of 310 samples from 712 herbaceous plants growing in the vicinity of infected trees contained PeAMV; the contaminated samples represented 12 species. The perpetuation of PeAMV by infected scion wood is probably of minor significance, and infection via the soil probably represents the most important means of spread of viral twig necrosis in northern Bavaria.
Determining the effectiveness of resistance to subterranean clover mottle sobemovirus in different genotypes of subterranean clover in the field using the grazing animal as virus vector
Authors: FERRIS D G , JONES R A C , WROTH J M 
Published: February 2008

SummaryThe effectiveness of resistance to subterranean clover mottle sobemovirus (SCMoV) previously identified in different genotypes of subterranean clover (Trifolium subterraneum) inoculated with infective sap in the glasshouse, was tested in two field experiments which used the grazing animal as virus vector. Replicated plots each consisting of paired test rows of 20 different genotypes were used. Clover plants infected with SCMoV were transplanted in between the paired test rows and these acted as sources of the virus for spread by grazing sheep. Although used in different years at different sites with different virus isolates, the field exposure methodology employed produced consistent results. The genotypes each behaved similarly in both experiments as regards the relative extents of SCMoV infection that developed, levels ranging from 0–98%. The previously identified resistance in six ‘highly resistant’ and three ‘partially resistant’ cultivars was effective under field conditions. However, the ‘partial resistance’ in three others was overcome, cvs Green Range and Mt Barker developing levels of infection approaching those in ‘susceptible’ cultivars, while an intermediate infection level developed in cv. Karridale. The three cultivars in which partial resistance was not effective all belonged to ssp. subterraneum. In subterranean clover breeding programmes, field screening using the grazing animal as a vector is advisable to determine whether SCMoV resistance found by sap inoculation is still effective under field conditions.
Environmental assessment of veterinary avermectins in temperate pastoral ecosystems
Authors: WRATTEN S D , FORBES A B 
Published: February 2008

SummaryAvermectins and their metabolites are excreted mainly in the faeces; they do not readily move from the site of dung deposition because of their low solubility in water and their tight binding to organic matter. Avermectins degrade in the environment through photodegradation and aerobic breakdown by soil organisms. The dung mesofauna potentially exposed to avermectin residues includes insects, earthworms, springtails, mites and nematodes. These organisms occupy a variety of different niches within the ecosystem and the faunal composition changes as the pats age. Some members of this fauna act in concert with soil microbial flora and assist in the breakdown of dung and consequent nutrient re‐cycling on pasture. There are marked seasonal patterns of faunal abundance and behaviour which affect their relative importance in the decomposer community. Some species of the coprophagous insect fauna, particularly in the larval stages, can be adversely affected by the presence of avermectin residues in the faeces. Veterinary use patterns of avermectins in temperate regions indicate that peak periods of insect activity and peak times of avermectin use are often asynchronous. When avermectin usage and insect activity do coincide, the heterogeneous patterns of administration to livestock and the focus of treatment on young animals result in the deposition on pasture of faeces which are predominantly free of avermectin residues. Results of large scale, long term studies indicate that, even under conditions of relatively high levels of avermectin use in cattle, the impact on non‐target insect populations and their function is limited.
Vectoring ability of aphid clones of Rhopalosiphum padi (L.) and Sitobion avenae (Fabr.) and their capacity to retain barley yellow dwarf virus
Authors: JING‐QUAN GUO , LAPIERRE HERVÉ , MOREAU JEAN‐PIERRE 
Published: February 2008

SummaryVectoring ability of four aphid clones, Rp‐M and Rp‐R26 of Rhopalosiphum padi and Sa‐R1 and Sa‐V of Sitobion avenae, to transmit barley yellow dwarf (PAV, MAV and RPV) luteoviruses (BYDV) was compared in controlled conditions. Significant differences between highly efficient vectors (HEV), Rp‐M and Sa‐Rl, and poorly efficient vectors (PEV), Rp‐R26 and Sa‐V, were found in transmission of their specific viruses with acquisition and inoculation access periods (AAP, IAP) of 5 days. BYD‐RPV was occasionally transmitted by both clones of S. avenae. None of 150 tested apterous adults of the Rp‐R26 transmitted BYD‐MAV, while 10% of transmission was observed from those of the Rp‐M in a parallel test. An improved ELISA and immuno‐PCR were adapted to test for viruses in aphids. The results obtained by the improved ELISA indicated there was a good correlation between virus detection in single aphids of HEV clones after a 5 day AAP and virus transmission by them. In contrast, the percentages of virus‐carrying aphids of PEV clones were generally higher than those of their transmission rates. BYD‐MAV and BYD‐RPV were also detected by the improved ELISA in single aphids of their PEV clones, with the exception of BYD‐RPV in those of Sa‐V. However, after a 2‐day IAP, the improved ELISA in most cases failed to detect these viruses in single aphids of PEV clones.Detection by immuno‐PCR demonstrated that all three viruses could be acquired and retained by the aphids of both HEV and PEV clones. But, as visualised from electrophoretic bands, after the 2‐day IAP the amplified products from aphid extracts of PEV clones were reduced. The detection in a batch of nine aphids by the improved ELISA revealed that virus content in PEV clones decreased more rapidly than that in HEV clones during transmission. Thus, the difference in transmission efficiency of the aphid clones within species was not caused by an inability to acquire virus, but was determined by variation in vectoring ability between them. This was due to differences in ability to prevent the passage of virions from haemocoel to salivary duct and/or different capacities for the retention of BYDV.