摘要:

SUMMARYThe historical records of the earliest reports of umbelliferous and other hosts of carrot fly (Psila rosae) are presented and their validity discussed. In addition, the results are reported of tests made between 1972 and 1980 on 27 species of Umbelliferae and three sub‐species ofDaucus carotato determine whether they would support the carrot fly. Techniques were developed for identifying plant species as hosts by determining the number of adult flies that emerged from root and soil samples obtained from plants exposed to carrot fly in the field. Experiments in 1979 and 1980 indicating the importance of co‐ordinating the life cycles of plant and insect. The results showed that certain annual species of Umbelliferae were unsuitable as hosts in the autumn when they has flowered and senesced. Valid records could only be obtained for these species by exposing the plants to first generation carrot fly attack. Of the 27 species tested,Anthriscus sylvestris, Ferula communis, and Smyrnium olusatrumfailed to support carrot fly and the following 13 species were new host records:Aethusa cynapium, Anthriscus caucalis, Apium inundatum, Apium nodiflorum, Bupleurum tenuissimum, Chaerophyllum temulentum, Cicuta virosa, Daucus capillifolius, Daucus glochidiatus, Heracleum mantegazzianum, Ligusticum scoticum, Oenanthe crocataandSison amomum. From two species,Chaerophyllum temulentumandTorilis japonica, more than two carrot flies/root were recovered. These species are numerous and widespread in carrot‐growing districts. The significance of these and other wild host plants in relation to the ecology and control of carrot fly is disc

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1982.tb07186.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARYAssays on adult females and eggs ofPanonychus ulmi, on leaf discs of Myrobalan plum, were used to characterise and establish homogenous organophosphateresistant (OR) and susceptible strains. Reciprocal crosses of these strains, and assays on adult mites and eggs of the parent, F1and F2generations confirmed that resistance was controlled by a single major gene, the expression of which was dominant in the response to parathion, and incompletely dominant to vamidothion, dimethoate and demeton‐S‐methyl. Reproductive incompatibility, between strains, as inTetranychus urticae, was not found.Bioassays on larvae hatched from winter eggs, collected from several orchards in Kent, Essex and Somerset, were used to evaluate the spectrum of cross‐resistance to a range of 20 organophosphates (OPs). Together with assays on adult females, these tests showed 10‐ to 100‐fold resistance to most of the OPs used for several years including those noted above, but less than 10‐fold to azinphos compounds and to several recently‐introduced OPs, e. g. dialifos, triazophos, dioxathion. The resistance spectrum in strain OR and five field strains was similar, but some had higher levels to parathion and demeton‐S‐methyl, and others to dioxathion after 3–4 years' exposure. Resistance levels to individual OPs may be enhanced by specific selection. Strains resistant to OPs showed only 2‐ to 5‐fold resistance to two carbamates, and were fully

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1982.tb07187.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARYAssays on eggs ofPanonychus ulmiheld on leaf discs of Myrobalan plum were used to characterise strains (1) multi‐resistant to organophosphates (OPs) and binapacryl (strain BR), (2) multi‐resistant to OPs and tetradifon (strain TR), and (3) susceptible to OPs, binapacryl and tetradifon (strain EM). By crosses of EM females and BR males, and of EM females and TR males, and by repeated backcrossing with EM males under selection pressure of the acaricides concerned, two strains were produced in which the specific genes for resistance to binapacryl and tetradifon were isolated in the genome of the EM strain. Reciprocal crosses of the resulting backcrossed strains with EM, assays on the F1eggs and the F2haploid eggs, confirmed the presence of single major genes for resistance to binapacryl and tetradifon, and the absence of maternal effects. The expression of gene BR was incompletely dominant in response to binapacryl, whilst gene TR was effectively dominant in response to tetradifon.Eggs of the field‐derived strain BR showedc.50× resistance to binapacryl, 8–19 × to dinobuton, but onlyc.2× to dinocap and dinoseb. The backcrossed strain was less resistant (26 ×) to binapacryl implying that resistance in strain BR was augmented by the effects of minor genes. Resistance to tetradifon (150–200 × on eggs) involved cross‐resistance to tetrasul (23 ×) and to chlorfensulphide (27×); resistance in the field‐derived strain appeared to depend on the major gene alone.Resistance mechanisms were highly specific in their effects, so that there was no cross‐resistance to unrelated acaricides, including amitraz, dicofol, cyhexatin, formetanate, chlordimeform, and quinomethionate. Fecundity of strain BR was 44% less than that of EM; laboratory and field evidence suggest that multi‐resistant mites tend to be less fit than susceptible mites. The practical im

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1982.tb07188.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARYIn 1978, 1979 and 1980, counts were made of the numbers of cereal aphids on a maize crop near Fordingbridge, Hampshire, England. Maize plants were selected away from the edge of the crop and the number, morph, species and feeding site of the aphids were recorded.Metopolophium dirhodumandRhopalosiphum padiwere found at densities that exceeded those found on small‐grain cereals and grasses at the same time of the year.Sitobion avenaeandMacrosiphum euphorbiaewere found at relatively low densities, andRhopalosiphum maidisandMetopolophium festucaewere observed rarely. Unlike other species, the numbers ofR. padicontinued to increase throughout the summer and reached a peak in September/October; at this time of the year,R. padiconstituted over 98% of the aphids found on maize.M. dirhodumandS. avenaewere found mostly on the leaves whereasR. padiappeared to favour the cob until populations became too large to be supported. If the area of maize grown in the UK increases, the crop will probably play an important role in the life cycle of cereal aphids (especiallyR. padi). It is suggested that further work should be carried out on the pest status of aphids on maize and on the role that maize may play in the ecology of cereal pest

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1982.tb07189.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARYThe pyrethroid, deltamethrin, alone or as an emulsifiable formulation, hindered infection of healthy plants with the persistent beet mild yellowing virus (BMYV) and both acquisition of, and infection with, the non‐persistent potato virus Y (PVY) and the semi‐persistent sugar beet yellows virus (BYV) byMyzus persicaein glasshouse tests.Another pyrethroid, RU‐15525, also protected against infection with PVY. Even sub‐lethal amounts of deltamethrin decreased virus transmission by rapidly incapacitating the aphids, the effect being least with aphids most resistant to organophosphorous insecticides and to certain pyrethroids including deltamethrin. Demeton‐S‐methyl hindered infection only with BMYV. This work shows that deltamethrin restricts transmission of persistent, semi‐persistent and perhaps more importantly of non‐persistent viruses in the glasshouse, and has potential for doing the sa

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1982.tb07190.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARYFewMyzus persicaesettled on polygodial (1 g litre‐1) or dodecanoic acid (5 g litre‐1)‐treated leaves and few nymphs were deposited. Polygodial decreased acquisition of the semi‐persistent beet yellows virus and the non‐persistent potato virus Y and dodecanoic acid that of the persistent potato leafroll and beet mild yellowing viruses, of beet yellows virus and of the bimodally‐transmitted cauliflower mosaic virus. However dodecanoic acid increased the acquisition of pot

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1982.tb07191.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARYAlternaria brassicicolalesions present on overwintered leaf litter ofBrassica oleraceaseed production crops produced high concentrations of spores in the spring, these were able to initiate new infections on foliage and subsequently on inflorescences and pods. A vertical disease gradient developed in maturing crops, the lowest pods becoming infected first and infection spreading slowly upwards. Spores were produced abundantly after 20 h leaf wetness at a mean temperature of 13°C or more. Their release was stimulated by a fall in relative humidity but inhibited at a constant high relative humidity resulting in a daily cycle in air spore concentrations with minimum numbers occurring in the early morning and maximum numbers in the early afternoon. For most of the growing season spore movement was restricted to within the crop, however, massive release of spores and subsequent distribution over a wide area occurred when the crop was cut and later threshed. Using semi‐selective agar traps spores released at these times were detected up to 1800 m downwind of the parent crop and were instrumental in infecting nearby young crops destined for seed production in the following seas

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1982.tb07192.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARYErgot sclerotia collected from one source germinated over a period of about 6 wk, but those from many sources, over a period of about 5 months. The duration of ascospore discharge followed a similar pattern.Individual ovaries of male‐sterile barley remained susceptible to infection for about 3 wk. After infection, 7 to 10 days elapsed before honeydew production started and this secondary source of inoculum (conidia) continued to be produced for about 2 wk in individual ovaries before ergot sclerotia started to develop.A field trial demonstrated that the duration of ovary susceptibility is lengthened in practice because of unevenness in flowering and the production of successive flushes of tillers. The potential for increase of the disease from a small primary focus of infection was large with the majority of the infections occurring in the back‐ or late‐ti

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1982.tb07193.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARYIn field experiments in Western Australia ammonium fertilisers significantly reduced the severity of root damage to wheat (Triticum aestivum) caused byGaeumannomyces graminisvar.tritici.A series of response lines depicting the effect of sources and rates of nitrogen on take‐all are presented. In general, the higher the rate of ammonium nitrogen used, the greater the reduction in the severity of take‐all. Ammonium sulphate and ammonium sulphate/mono‐ammonium phosphate mixture were more effective in reducing disease than di‐ammonium phosphate, urea or ammonium nitrate. Sodium nitrate did not reduce t

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1982.tb07194.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARYA maturation index summarising pseudothecial development ofVenturia inaequaliswas devised. The index demonstrated differences in overwintering on 10 apple cultivars and the crab appleMalus toringoin experiments over two winters. At about the green cluster stage, when there is a high proportion of susceptible foliage, there were 50–100 fold differences in the yield of ascospores from these hosts, due mainly to different rates of pseudothecial maturation. These rates were shown to be independent of cultivar differences in colony numbers on leaves in the previous autumn.Cultivar differences in the timing of fruit bud development were independent of differences in the overwintering ofV. inaequalis. These findings confirm the importance of considering cultivar identity in apple scab managemen

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1982.tb07195.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY