摘要:

SUMMARYSignificant correlations were found between the numbers of apple rust mitesAculus schlechtendalifeeding on fruitlets shortly after the blossom period and the amounts of russet on the calyx‐end and cheek of apples at harvest. Stalk‐end russet was not usually affected. Fruits from clusters or trees on which rust mite numbers had been reduced with an acaricide pre‐blossom had less calyx‐end and cheek russet than apples from untreated comparisons. Histological studies showed that feeding by mites on flower receptacles/fruitlets in May and June damaged epidermal cells, resulting in russet fo

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1986.tb03178.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

SUMMARYSignificant linear relationships between the mean number of sciarid,Lycoriella auripila, larvae/125 g‐sample of casing and yield, numbers of mushrooms and weight/mushroom were demonstrated at all stages of a mushroom crop. Negative relationships were obtained for yield throughout the cropping period. There was no injury threshold for this pest, although an economic threshold of one larva/sample was deduced. Loss in yield was mostly due to the destruction of mushroom primordia and presumed interruption of nutrient supply to the developing sporophores.Numbers of mushrooms were severely reduced in the first, second and third flushes, more so than yield, although a large increase in numbers was demonstrated in the fourth flush. The size of mushroom was inversely related to numbers, although the increases in size in the first three flushes were insufficient to compensate for the reduction in numbers. A reduction in size was evident in the fourth flus

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1986.tb03179.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

SUMMARYA preliminary morphometric analysis of alateMetopolophium dirhodumwas carried out. The alate morphs studied were: gynoparae and alate emigrants (collected fromRosa), summer exules (collected from maize in the field and from wheat in the laboratory) and winter exules (collected from grasses). Comparing the different morphs using canonical discriminant function analysis gave good separations (always in excess of 80% and often 100%). If this result is found to hold for specimens from a wider temporal and geographical range, it may be used to determine the sources of flying alatae, particularly spring colonists.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1986.tb03180.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

SUMMARYInvestigation of the dispersal ofLiriomyza trifoliiin a 1–2 ha chrysanthemum greenhouse indicated that the average distance flown by female flies was greater than that flown by male flies. However, flies of both sexes were found at the furthest distance from the release point (102 m) which indicates that flies in the greenhouse could be considered to be a single inter‐breeding population. When the data were fitted to a generalised distance‐dispersal model, examination of the parameters revealed density decreased with distance more rapidly for males than females. Also, the model showed that males tended to be slightly more attracted to each other than were females. The applicability of these results to the development of pest management systems forL. trifoliiis disc

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1986.tb03181.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

SUMMARYLiriomyza bryoniae, L. huidobrensis, L. sativaeandL. trifoliiare leafminers of great economic importance; morphologically they are difficult to separate, many being inseparable at the pre‐adult stages. Horizontal starch gel electrophoresis of larvae, pupae and adults was carried out in order to search for diagnostic allozymic characters. Analysis of the variation patterns at 15 genetic loci reveals that each species can be identified at all three stages of the life cycle. A biochemical key is presente

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1986.tb03182.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

SUMMARYExperiments were carried out in 1981‐83 to assess the impact of polyphagous predators (e.g. Carabidae, Staphylinidae and Araneae) on populations of cereal aphids in spring barley in Sweden. Barriers were erected around mid‐field and field‐edge plots at different times during the aphids' establishment phase in order to manipulate the predation pressure during the aphid pre‐peak period; predators were emigrating from field boundaries.Rhopalosiphum padiwas the dominant species of cereal aphid in 1981 and 1982, and was abundant in both years. Reduction of the predation pressure resulted inR. padipopulations that were two to six times larger compared with those in unenclosed control plots. Aphid populations were much larger when the predation pressure was reduced earlier in June than when this was done later, in both years, since late erection of barriers excludes fewer predators because most had already entered the enclosed areas. In 1983,R. padi and Sitobion avenaewere equally common but occurred in low numbers, and the effects of reducing the predation pressure were less obvious.Bembidionspp.(B. lamprosandB. quadrimaculatum)and linyphiid spiders were the most abundant predators during the early establishment phase of aphid populations in each year, and significant inverse correlations were found between peak numbers ofR. padiper shoot and numbers of predators from these taxa in 1981 and 1982. Similar relationships were found between total aphids and numbers of Staphylinidae,B. quadrimaculatumandCoccinella septempunctatain 1983.It was concluded that differences between the manipulated numbers of polyphagous predators caused the observed differences in peak population levelsof R.padiin1981,1982 and to a lesser extent, 1983. Apparent levels of parasitism and fungal disease were low during the pre‐peak period. Aphid specific predators, abundant after the peak, were considered partly responsible for the decline of aphid populations each year.The results are compared with those from similar experiments elsewhere withS. avenaeandMetopolophium dirhodumin winter wheat. Reasons why the effects of polyphagous predators are greater, and occur over a much shorter period of time in Sweden are

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1986.tb03183.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

SUMMARYNumbers of eggs and larvae of thrips{Kakothrips pisivorus(Westw.)) infesting pistils of various stocks of faba beans(ViciafabaL.) were recorded in different environments. By the end of flowering in spring beans, 25 times as many flowers were infested with, on average, twice as many thrips, as at the onset of flowering in winter beans. Within each of two seasons, levels of infestation varied up to 30‐fold with location. At a single location, some bean stocks were much more heavily infested (greater proportions of flowers contained thrips and/or greater numbers of thrips per infested pistil) than others. Levels of infestation were not clearly associated with the closed‐flower character(cf).Stocks with lush growth were more heavily infested than those with either generally restricted growth or with terminal inflorescences(ti).Those with white flowers, long pods or cytoplasmic male‐sterility were more infested than those which contrasted for these three characters. The path of the pollen tubes was blocked by eggs of thrips in less than 0–5% of flowers. Infestation had no apparent effect on the fertilisation of

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1986.tb03184.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

SUMMARYCarrot, cauliflower and radish seedlings raised in sand culture and treated with aqueous suspensions containing chlorfenvinphos, diazinon, iodofenphos or triazophos were planted into the field in 1982 and 1983 to compare the performance against cabbage root fly and carrot fly of these treatments with that of bow‐wave applications of granular formulations at sowing.Initial residue concentrations were up to 4100 mg kg‐1in the seedlings at planting. Thereafter the amounts of insecticides per root system declined. Residue concentrations in mature carrot and radish roots were smaller when plants had been treated as seedlings rather than by bow‐wave application. Chlorfenvinphos was the most effective insecticide against both pests. Amounts of insecticide applied in transplanted seedlings were<5% of the amounts applied by the bow‐wave method but short‐term control of cabbage root fly on radish was similar. Carrot fly damage was reduced by 60% by some of the seedling treatments after 16 wk in 1982 but in 1983 they were less effective.Pot experiments with chlorfenvinphos showed that most of the insecticide in the seedlings was transferred rapidly into the surrounding soil and it was concluded that the bioactivity resulted mainly from uniform distribution of the released insecticide between and around individu

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1986.tb03185.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

SUMMARYInfection of leaves and stems ofPsophocarpus tetragonolobusbySynchytrium psophocarpionly occurred following spray inoculation of motile zoospore suspensions and incubation for a minimum of 12 h in polyethylene bags or a mist chamber. The incubation period was 7 days and generation time 22 days at temperatures of 31oC max, 24oC min and r.h. of 90% max, 70% min. Young, 1–2 day‐old leaves were most susceptible; there was no infection on 10 day‐old leaves and susceptibility was not increased by the removal of leaf waxes.No infection occurred when plants were grown from seed from infected pods, seed inoculated with zoospores or sporangia and seed sown in soil containing infected leaf debris. Resting spores were not found in infected tissues stored for 12 wk or in plant debris.S. psophocarpidid not infectArachis hypogaea, Glycine max, Phaseolus aureus, P. coccineus, P. vulgaris, Pisum sativum, Psophocarpus scandens, Vicia faba, Vigna sesquipedalisandV. unguiculata. S. minutumdid not infect winged bean.Inoculation confirmed the susceptibility of the winged bean lines UPS 62, UPS 122, UPS 126 and resistance of two Thai winged bean lines 1602/1 and 1

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1986.tb03186.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

SUMMARYRadial growth of oat and non oat‐attacking Australian isolates ofGaeumannomyces graminiswas greatly inhibited by increasing concentration of DL‐cysteine in basal medium agar, and growth was completely inhibited by cysteine concentrations of 3 μM. As a group, isolates ofG. graminisvar.tritici(both oat and non oat‐attacking forms) were more inhibited than isolatesof G.graminis var.avenaeat 1 μMcysteine, but differences did not occur at other concentrations. Isolates of a lobed‐hyphodiate fungus similar toG. graminisvar.graminiswere more tolerant of cysteine than other isolates.The findings indicate thatin vitroinhibition of AustralianG. graminisisolates by cysteine is not useful for differentiation between oat and non oat‐attacking types, and is unlikely to be fundamentally related to the ability of isolates to

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1986.tb03187.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY