摘要:

SUMMARYAphid populations were evaluated on foliage samples within an experimental forest area. There were marked differences in aphid density between three areas within the experiment and between individual trees. Significant differences between provenances of Sitka spruce were of particular interest since aphid density appeared to be related to the latitudinal origin of the seed. The more southerly provenances were especially susceptible. The accumulated evidence suggests that no single physiological difference between trees will account for all observed variations in aphid density although the later growth cessation of susceptible provenances deserves further study.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb03066.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SUMMARYAn ELISA was developed which would detect and quantify ingested aphids in predators found in and around cereal crops. The detection limit of the assay was less than one hundredth of an homogenised adult aphid. Tests with 13 species of aphid showed that those which had been used as the principal immunogens reacted most strongly in the assay. Nearly a hundred species of invertebrates, both predators and alternative prey, have been tested in the assay and no evidence of significant cross‐reaction was found with any of these species or with a number of samples of plant material on which aphids may be found. Aphid material could still be detected in predators which had been stored for up to 7 days in 4% formalin or 70% ethano

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb03067.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SUMMARYSoil samples (0·04 m‐2) were taken from December to January in 1981‐82 and 1982‐83 from five crop and two non‐crop habitats on farmland in Hampshire to quantify the distribution and abundance of overwintering polyphagous predatory arthropods. Total numbers of overwintering polyphagous predators were greater in field boundaries, winter‐sown cereals and established grassland than in the other four habitats. Many individual species overwintered in significantly higher densities in field boundaries than in any other habitat; others predominated in woodland, grassland and winter‐sown cereals. The carabidsAgonum dorsaleandDemetrias atricapillus, probably the most important predators of cereal aphids, overwintered almost entirely in fiel

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb03068.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SUMMARYThe effect of corn stunt spiroplasma (CSS) on survival and fecundity of threeDalbulusleafhopper species was determined. CSS significantly reduced the survival, as measured by the time to 50% (t50) and 25% (t25) survival, and by the scale parameter (b) of the Weibull model, forD. elimatusandD. gelbus.Fecundity of these two species, as measured by the net and gross reproductive rates, was also reduced by CSS. CSS did not significantly affect the corn leafhopper,D. maidis.In a separate experiment, maize bushy stunt mycoplasma (MBSM) reduced the survival and fecundity ofD. maidisat temperatures from 20 to 29 °C. The effect of MBSM onD. maidissurvival was less severe than CSS onD. elimatusandD. gelbus; t25, but nott50, was reduced by MBSM. Survival times and the cohort generation time generally declined with increasing temperature. Fecundity, however, generally increased with increasing temperature

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb03069.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SUMMARYIndividual chrysanthemum cuttings and leaves infested with eggs and larvae of the alien leaf minerLiriomyza trifolii, and batches of pupae, were treated in the laboratory to find an effective quarantine treatment to control the pest in imported cuttings. The laboratory tests were based on a statutory quarantine treatment of 2 days' cold storage at 1–2°C followed by methyl bromide fumigation at 15°C with a concentration time product (CTP) of 54 g h/m3, which is used to controlSpodoptera littoralison imported chrysanthemum cuttings. Treatments of 2 days' storage at 1–2°C followed by methyl bromide fumigation at 15°C with a range of CTPs were used to obtain accurate dose‐response lines and estimate the LD99 and LD99 9 for each stage ofL. trifolii.The largest estimates of the LD99 for eggs, larvae and pupae up to 3 days old were 40·04, 34·49 and 42·64g h/m3respectively. These results indicate that theSpodopteratreatment should give high levels of kill of most stages ofL. trifolii.However, the LD99 values for pupae more than 3 days old were greater than those for eggs, larvae and young pupae. Therefore if this treatment were adopted as a quarantine measure againstL. trifolii, good prophylactic treatments and rigorous pre‐packing inspections in exporting countries would need to be maintained, to minimise any risk of importing pupae. It would also be necessary to ensure that the temperature of the imported cuttings was raised uniformly to 15°C after cold storage and prior to fumigation. The practicality of the technique as a commercial treatment will depend on whether it is possible to achieve this without causing unacceptabl

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb03070.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SUMMARYThe saprophytic survival of the pathogen,Gaeumannomyces graminisvar.triticiand two isolates each of three avirulent fungi,G. graminisvar.graminis, Phialophora graminicolaand a lobed‐hyphopodiatePhialophorasp. was studied in two soil types under controlled temperature and moisture conditions in the laboratory. In general, the fungi survived longest in the cool, dry soil (15°C,<‐10 MPa) followed by the warm dry soil (30°C,<‐10 MPa). All the fungi were virtually eliminated from the warm, moist soil (30°C, ‐0.3 MPa) after 3 months. Survival was intermediate under cool, moist conditions (15°C, ‐0.3 MPa). Under cool, moist conditions,G. graminisvar.graminissurvived better than the other three fungi in the first 3 months in both soil types and continued to do so for a further 3 months in one soil. Both isolates of the lobed‐hyphopodiatePhialophorasp. survived poorly in the two soil types being almost eliminated after 3 months. There were considerable differences between the survival of the two isolates each ofG. graminisvar.graminisandP. graminicola, especially under cool, moist conditions. Of the six avirulent isolates studied, one isolate ofG. graminisvar.graminis(DAR24167) survived best under the three temperature‐moisture regimes which showed differences. It also survived better than the take‐all fungus under moist, cool conditions and at a comparable rate under dry conditions. Therefore, this variation in survival should be considered when selecting antagonists for the biological

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb03071.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SUMMARYAntisera toPhoma exiguavar.foveataand var.exiguawere prepared by injecting rabbits and mice with protein solutions from mycelium. Specific antibodies were isolated and immunoenzymatic techniques (double antibody sandwich ELISA and indirect ELISA) were used to test for the fungus in inoculated tubers and sprouts and in stems grown from these tubers. The fungus was detected in these different tissues, withvar. foveatabeing more aggressive, demonstrating the applicability and sensitivity of the techniques. The antibodies produced to the two varieties of the fungus were not specific to their own varieties. They also reacted withPhoma tracheiphilabut did not react with several other common potato pathogens. Preliminary results obtained with antibodies from mouse ascite liquid suggest the possibility of producing specific monoclonal antibodies.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb03072.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SUMMARYA new selective medium containing pentachloronitrobenzene and 2‐aminobutane (the PAB medium) was developed for soil‐dilution plate enumeration of fungal propagules ofFusarium solanivar.coeruleumandF. sulphureumfrom field soil. Growth of ‘weed‐fungi’ was less on the PAB medium than on the previously developedF. solanivar.coeruleumisolation medium (the PM70 medium) and significantly more propagules ofF. solanivar.coeruleumwere detected.Propagule counts (x) ofF. solanivar.coeruleumandF. sulphureumfrom the PAB medium, after log10(x/10 + 1) transformation, were linearly related to the angular transformation of measurements of soil infectivity from the tuber bait method using the susceptible cv. Catriona. Slopes from disease‐inoculum regressions forF. solanivar.coeruleumandF. sulphureumin November and May were similar and this suggests that the mode of pathogenic action ofF. solanivar.coeruleumandF. sulphureumwas similar. Recently harvested tubers, inoculated in November, however, were more resistant to infection by both pathogens than stored tubers inoculated in May. Storage of air dry soil at 4°C for 6 months reduced the population ofF. sulphureumbut not the population ofF. solanivar.coeruleum.Whereas the PAB medium is recommended primarily for use in the isolation ofF. solanivar.coeruleumandF. sulphureumfrom field soil, the PM70 medium appears to be more suitable for recovery of these pathogens and others, includingPhoma exiguavar.foveatafrom diseased

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb03073.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SUMMARYDNA probes, made by cloning double‐stranded forms of each of the genome parts (DNA‐1 and DNA‐2) of the Kenyan type isolate of African cassava mosaic virus (ACMV‐T), reacted strongly with extracts fromNicotiana benthamianaplants infected with ACMV‐T, or with Angolan or Nigerian isolates that are closely serologically related to the type isolate. However, only the DNA‐1 probes reacted with extracts of TV.benthamianainfected with a Kenyan coast isolate (ACMV‐C), which is serologically less closely related to ACMV‐T. DNA‐1 and DNA‐2 probes also reacted with extracts of mosaic‐affected Angolan cassava plants, including some which have not yielded ACMV particles detectable by immunosorbent electron microscopy and from which virus isolates have not been transmitted to TV.benthamiana.These anomalous plants, unlike other naturally infected cassava plants, showed mosaic symptoms on all their leaves which, however, contained only traces of virus particle antigen detectable by enzyme‐linked immunosorbent assay. They contain isolates of ACMV that are probably defective for particle production.ACMV‐T particles accumulated optimally inN. benthamianaat 20–25°C. At 30°C fewer particles, which apparently had a slightly greater specific infectivity, were produced. At 15°C, considerable quantities of virus particle antigen, virus DNA and virus particles were produced but the particles were poorly infective, and the few that could be purified contained an abnormally large proportion of polydisperse linear DNA molecules, and fewer circular molecules than usual. Angolan isolates, whether particle‐producing or not, likewise replicated better in cassava plants at 23 °C than at 30 °C. In contrast, ACMV‐C attained only very low concentrations inN. benthamiana, but thes

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb03074.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SUMMARYA new virus, peanut stripe (PStV), isolated from groundnut (Arachis hypogaea) in the USA, induced characteristic striping, discontinuous vein banding along the lateral veins, and oakleaf mosaic in groundnut. The virus was also isolated from germplasm lines introduced from the People's Republic of China. PStV was transmitted by inoculation of sap to nine species of the Chenopodiaceae, Leguminosae, and Solanaceae;Chenopodium amaranticolorwas a good local lesion host. PStV was also transmitted byAphis craccivorain a non‐persistent manner and through seed of groundnut up to 37%. The virus remained infective in buffered plant extracts after diluting to 10‐3, storage for 3 days at 20°C, and heating for 10 min at 60°C but not 65°C. Purified virus preparations contained flexuous filamentous particlesc.752 nm long, which contained a major polypeptide of 33 500 daltons and one nucleic acid species of 3·1 × 106daltons. In ELISA, PStV was serologically related to blackeye cowpea mosaic, soybean mosaic, clover yellow vein, and pepper veinal mottle viruses but not to peanut mottle, potato Y, tobacco etch, and peanut green mosaic viruses. On the basis of these properties PStV is identified as a new potyvirus in g

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb03075.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY