ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1990.tb06622.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

SummaryCultivars of Brassica juncea, B. napus and B. campestris, differing in host‐suitability to the mustard aphid (Lipaphis erysimi pseudobrassicae Kalt.), were analysed for their phloem sap content of free amino acids. Sap was collected from excised mustard aphid stylets and analysed by means of high performance liquid chromatography. Aspartic and glutamic acid were, together with glutamine, the dominating amino acids. All plants had very little glycine, γ‐aminobutyric acid (GABA), methionine and tryptophan in their sap. This amino acid pattern closely resembled that of cereals. The total concentration and the individual composition of amino acids were not found to be related to the level of aphid resistance previously found in the investigated Brassica species. However, one B. campestris cultivar, yellow sarson YSB‐9, on which the aphids were shown to grow more slowly, had less amino acid content than other B. campestris varieties. The slow population growth of aphids on B. juncea, compared to that on B. campestris, is probably due to other than nutritional f

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1990.tb06623.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

SummaryThe reproductive rate of the Indian mustard aphid (Lipaphis erysimi pseudobrassicae), a serious pest on Brassica oilseeds in India, was compared with that of Swedish strains of mustard aphid (L. e. erysimi) and cabbage aphid (Brevicoryne brassicae) on six common Indian and Swedish Brassica oilseed cultivars. There were clear differences between L. e. erysimi and L. e. pseudobrassicae in the relative suitability of the cultivars, emphasisipg the biological differences between these aphids. B. brassicae had similar reproductive rates on all cultivars.In addition, the reproductive rate of L. e. pseudobrassicae was measured on both young and old plants of the six Brassica oilseed cultivars and 14 Indian rai (B. juncea) cultivars. Among the six Brassica cultivars, the reproductive rates were highest on turnip rape and toria (B. campestris), and lowest on yellow sarson (B. campestris) and rai (B. juncea). The ranking of the cultivars was similar for young and old plants. There were no significant differences between the rai (B. juncea) cultivars tested, neither among young nor among old plants. These results from laboratory studies are compared with field data from India on the relative susceptibility of different Brassica oilseed cultivars to L. e. pseudobrassicae.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1990.tb06624.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

SummaryVisual stimuli influence the orientation behaviour of the sorghum midge, Contarinia sorghicola Coq. (Diptera: Cecidomyiidae). Yellow, red and white colours are attractive to the midge while blue and black are least attractive. Sorghum panicles covered with blue‐ or black‐coloured bags in a headcage showed maximum midge damage, while the reverse was true for panicles covered with yellow, red, and white coloured bags.Panicles at half‐anthesis with viable pollen and receptive stigmata suffered higher damage than those at the pre‐ and post‐anthesis. Physical removal of anthers and stigmata significantly reduced the oviposition by the sorghum midge. Reduced oviposition/adult emergence was also recorded in male sterile sorghum lines (2219A and 296A) or through chemically‐ (Ethrel) (2‐Chloro ethyl‐phosphonic acid) induced male sterility in panicles of the sorghum cultivar, Swarna. Chemical stimuli from viable pollen and receptive stigmata and to a limited extent physical stimuli, govern the oviposition behaviour of the sorghum midge.Sorghum cultivars IS 12573C, S‐GIRL‐MR1 and IS 2816C showed antixenosis to adult midges. However, these cultivars became susceptible under no‐choice conditions in the headcage. DJ 6514 and IS 12666C were attractive to the adult midges, but showed antixenosis to oviposition under natural and no‐choice conditions. Genotypes with short florets showed antixenosis for oviposition. Ovary and anther breadth and tannin content of grain showed negative associations with oviposition. Cultivar antixenosis to adult midges and oviposition is an important component of resistan

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1990.tb06625.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

SummaryThe relative, effectiveness of Rebell®, small cylinder, large cylinder, windmill and water traps, the five types of trap used currently for monitoring populations of the carrot fly, Psila rosae, was assessed in nine field experiments, three in south west Lancashire, four in the Fens (Suffolk, Norfolk, Cambridgeshire), one in East Suffolk and one at Wellesbourne, Warwickshire. Regression analysis of the numbers of flies caught on each type of trap against the numbers caught on the Rebell® trap indicated that each trap samples a constant proportion of the fly population relative to the other traps. Therefore, provided the fly population was sufficiently large for insects to be caught on the least effective traps, any of the five traps would monitor adequately fluctuations in carrot fly populations. However, the Rebell® trap caught 4–17 times as many flies/trap and 5–7 times as many flieshnit area of trap as any of the other traps tested.Operators considered the Rebell® trap to be the easiest to use. However, it was more expensive than any of the other traps

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1990.tb06626.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

SummarySix different types of traps were compared for capturing adults of Delia radicum. Cone traps caught so few flies that it seems inadvisable for them to be used for monitoring populations of this pest. All the other traps tested were suitable for monitoring D. radicum populations. When expressed on a trap for trap basis, the large 1800 cm2Canadian traps caught most flies. When expressed as the numbers of flies caughthnit area of trapping surface, most flies were caught in the water traps. Similar numbers of D. radicum, D. platura, syrphids, blowflies and a tachinid, Eriothrix rufomaculatus were caught per unit area on each of three different vertical sticky traps. Although water traps have the advantage that they catch about 5 times as many females D. radicum/unit area as the most effective vertical sticky traps of a comparable size, their disadvantage is that they catch about 10 times as many beneficial syrphids. The reasons why water traps are so effective against D. radicum are discussed, with details of how to convert water‐trap data to sticky‐trap equivalents, and vice ve

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1990.tb06627.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

SummaryThe biosynthesis of lipids in the mycelium and sporophore of Pleurotus sajor caju was studied. Whereas in the mycelium the biosynthesis of lipids was directly primarily towards storage (e.g. tri‐acylglycerols), in the sporophore it was directed towards structural components (e.g. sterols). The incorporation of14C precursors into non‐polar and polar lipid fractions was generally similar for14C acetate,14C palmitate,14C oleate and14C linoleate in the case of mycelium and sporophore. It appears that linoleic acid was utilised as a source of acetate for lipid biosynthesis in the sporophore. A significantly higher incorporation of label was seen in sporophore sterol than in mycelial sterol. Malate dehydrogenase activity increased in the mycelium grown in the presence of lipids. Lipase of P. sajor caju was inducive. The growth of P. sajor caju was enhanced by increased lipid utilisation. The implications of these results on commercial cultivation of this fungus are discus

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1990.tb06628.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

SummaryBig‐vein diseased lettuce plants contained an agent that could consistently be transmitted mechanically to Chenopodium quinoa, in which it caused characteristic local lesions. Mechanical transmission was also possible to five other plant species including Nicotiana benthamiana, N. clevelandii and N. occidentalis, but not to lettuce. Symptoms in N. occidentalis were reminiscent of those of tobacco stunt disease. With zoospores of originally virus‐free Olpidium brassicae, subcultured on the roots of N. occidentalis‐P1, sap‐inoculated either from lettuce or via C. quinoa, the agent could be transferred back to lettuce in which characteristic symptoms of big‐vein were reproduced.Infectivity in sap at room temperature was reduced by half after 2 h, and was practically lost after one day. Thermal inactivation was considerable at 45°C and complete at 50°C. Most infectivity was lost at dilution 1:5, and the dilution end‐point was 1:10. The agent survived well in leaf material stored at ‐80°C, or in sap from leaves ground in buffer with DIECA and activated charcoal and freeze‐dried. Mechanical transmission required low dilution (1:2) in the buffer with charcoal, and chilling of materials and utensils.In lettuce, N. occidentalis‐P1 and C. quinoa, with all isolates tested but one, infection was always associated with the presence of rod‐shaped particles which in the literature have been associated with lettuce big‐vein, and are similar to those described for tobacco stunt. Results obtained corroborate the assumption that these particles are the virions of lettuce big‐vein virus. The virus also resembles tobacco stunt virus in mechanical transmissibility, instability in sap and s

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1990.tb06629.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

SummaryExperiments were made at Invergowrie in 1984 and 1985 to compare the spread of potato leafroll virus (PLRV) after removing infected plants by three different methods; conventional roguing, desiccation with diquat, or incineration for 45–60s using a propane gas flame. Potato leaf roll ‘infector’ plants, grown in plots of virus‐free Maris Piper seed potatoes, were artificially infested in June with aphids (Myzus persicae) from a laboratory culture, and removed from the plots after 2 or 3 wk. In both years, natural infestations of potato aphids were scarce during this period. There was no significant difference in the proportion of tubers infected with PLRV in adjacent plants after the neighbouring infector plants had been rogued by hand or desiccated with diquat, but the proportion was considerably reduced following incineration of the infector plants. In 1984, the spread of PLRV in conventionally rogued plots was also significantly reduced by a mixture of deltamethrin plus heptenophos, applied four times from 80% crop emergence, and was almost eliminated by a treatment with aldicarb granules, either at planting, or as a side‐dressing 5 wk later. In 1985, delaying infector removal by 8 days in early July significantly increased the spread of PLRV to neighbouring plants from 2.3% (1 July) to 8.3% (9 July). A single application of deltamethrin plus heptenophos to infectors 1 wk before removal did not significantly decrease spread. Although incineration was quick and effective, the value of this method of eradicating infector plants in seed potato crops is limited because it failed to destroy infect

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1990.tb06630.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

SummaryBecause there is some evidence that June Yellows (JY) of strawberry may be caused by a pathogenic agent, combinations of heat treatment and meristem‐tip culture that are known to eliminate some viruses from tissues were used in attempts to cure affected Cambridge Favourite strawberry plants from JY. None of 397 propagants derived from JY‐affected plants subjected to various combinations of these treatments were freed from JY. Indeed, all propagants showed more obvious JY symptoms than the parent plants from which they were derived, suggesting that such treatments may be useful for detecting incipient JY in symptomless strawberry sto

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1990.tb06631.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY