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Wednesday, July 29, 2020 | History

2 edition of Effects of weather on the numbers of cereal aphids. found in the catalog.

Effects of weather on the numbers of cereal aphids.

Shirley Jean Watson

Effects of weather on the numbers of cereal aphids.

by Shirley Jean Watson

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  • 37 Currently reading

Published by University of East Anglia in Norwich .
Written in English


Edition Notes

Thesis (Ph.D.) - University of East Anglia, School of Biological Sciences 1983.

ID Numbers
Open LibraryOL13809291M

Aphid activity greatly reduces at temperatures below 3°C, and virus inoculation efficiency decreases to 23–25% at temperatures below 6°C. Crops suffer little yield loss from new infections after growth stage The effects of BYDV can be exacerbated by other stress factors, including adverse weather, soil acidity and other pests or diseases. landscape on the abundance of insect predators of cereal aphids was studied in wheat fields in eastern South Dakota, USA. Cereal aphids, aphid predators, and within-field vegetation were sampled in fields over a three year period(–).The compositionand patchinessof the landscape surroundingeach field were determined.

Identification and general discussion of the cereal aphid species most commonly found in Nebraska small grains, corn, sorghum and millet. Cereal aphids can be a serious threat to several Nebraska crops. Aphid feeding may cause direct damage to the plant or result in transmission of plant diseases. Aphids .   We examined the effects of prior infestation by the Russian wheat aphid [Diuraphis noxia (Mordvilko)] and the bird cherry-oat aphid [Rhopalosiphum padi (L.)] on the subsequent feeding preferences and performance of each species. Aphid colonies fed and reproduced on wheat seedlings for five days and were then removed. After a period of plant recovery, we estimated aphid population .

Aphids are small sap-sucking insects and members of the superfamily names include greenfly and blackfly, although individuals within a species can vary widely in colour. The group includes the fluffy white woolly aphids.A typical life cycle involves flightless females giving living birth to female nymphs—who may also be already pregnant, an adaptation scientists call. Cereal aphids cause direct damage to rainfed wheat through sucking of plants sap and cause losses of up to 90%, particularly in dry years in Kenya. The Russian wheat aphid (RWA) is the most destructive and may account for up to 50% yield loss or more depending on the severity and length of infestation. Current control strategies mainly rely on the use of insecticides to control cereal aphids.


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Effects of weather on the numbers of cereal aphids by Shirley Jean Watson Download PDF EPUB FB2

Experimental evidence regarding the responses of cereal aphids to rising atmospheric CO 2 has been ambiguous. Some studies suggest increased population sizes under future CO 2 levels, others suggest decreased population sizes, and still others suggest little or no difference.

Recently, Newman et al. () constructed a general mathematical model of the aphid–grass interaction to Cited by: cereal aphid (see below). An unexplained phenonlenon occurs in the relationship ofautumn and spring numbers of cereal aphids trapped inCanterbury during six years (Fig. Alate cereal aphids flyinlate autumn on toseedling wheat crops, and give birth to nymphs which become the nucleus for spring populations.

Data for the years and File Size: 1MB. Once aphid populations become established in a crop, higher rates of insecticides are required to reduce high aphid populations and to minimise their feeding damage.

The recommended threshold to apply insecticide is 50% of cereal tillers have 15 or more aphids and crops are expected to yield three tonnes/ha or more. Cereal aphids and their natural enemies were sampled three times per year during the peak of cereal aphid populations from 5 to 25 May in – by both visual observation and hand collection.

In each site, five randomly selected spots were used for insect sampling in the wheat fields (Zhao, He, & Hui ).Cited by: Effects of weather on the numbers of cereal aphids Author: Watson, S.

Awarding Body: University of East Anglia Current Institution: University of East Anglia Date of Award: Availability of Full Text. of the crop because small numbers of surviving aphids are no longer controlled by natural enemies. the lifecycle of a cereal aphid When winged cereal aphids fly into crops from grass weeds, pasture grasses or other cereal crops, colonies of aphids start to build-up within the crop.

In Australia, all aphids in a cereal crop are females, able to. Introduction. Although there are approximately 5, species of aphid across the world, only a handful pose a threat to cereal production.

Those that do can commonly be termed ‘cereal aphids’, which can cause both direct damage to cereal crops such as wheat and barley but importantly transmit a number of viruses, such as Yellow Dwarf Viruses, that can cause even greater damage to.

Laboratory and field studies on aphid damage in wheat are described. Both direct and indirect effects of aphids on the behaviour of the crop were studied. In the laboratory a clear effect of honeydew and yeasts on photosynthesis was found. This effect could not be demonstrated under field conditions, since even at yield loss levels of kg ha−1 the size of this effect may be undetectable.

Cereal aphids (corn aphids and oat aphids) have been found in a large number of cereal crops in the Victorian Mallee, Victorian Northern Country and New South Wales Riverina. The severity of infestations ranged from moderate to severe, and control was required in at.

A family (Aphididae) of small insects, in the suborder Sternorrhyncha, that suck the juices of plants. Important genera include Schizaphis and | Explore the latest full-text research PDFs.

Winter cereal growers face an increased risk of a key aphid-spread disease due to the mild autumn and seed dressings running out of steam unless there is a prolonged cold period of weather.

Aphid. Effect of nitrogen fertilizer. In the experiment, the amount of nitrogen fertilizer ranged from kg/ha to kg/ha while the proportion of cropland ranged from % to % (see supplementary Table S1).In total, we collec individuals includ cereal aphids, 3, primary parasitoids, leaf-ground predators, and ground-dwelling predators.

The effects of five rates of nitrogen fertiliser applications on the performance of the cereal aphid Metopolophium dirhodum on winter wheat, within the range of rates recommended for UK crops, were investigated over two seasons in field-grown crops and also on plants grown in the glasshouse.

Longevity was unaffected by the level of fertilisation, but aphid intrinsic rate of increase and. Cereal aphids frequently cause significant damage to English winter wheat crops, and aphicide sprays are often applied in response to perceived aphid risk (Davies, Garthwaite & Thomas,l; Oakley.

BioSystems, 18 () Elsevier Scientific lCublishers Ireland Ltd. SIMUI~TION:MODELLING OF THE POPULATION DYNAMICS OF CEREAL APHIDS NICK CARTER Entomology Department, Rothamsted Experimental Station, Harpenden, Herts AL5 2JQ (U.K.) (Received April 15th, ) A simulation model explaining the population dynamics of the grain aphid.

English Grain Aphid, Sitobium avenae Mordvilko, is a pest aphid appearing in cereals especially wheat as grain begins to fill.

Historically they have been reported as causing economic loss at 25 aphids per grain head. Newer estimates of EGA damage occur at 50 aphids per tiller before and during the milk stage of grain fill.

Vereijken, P. in Feeding and multiplication of three cereal aphid species and their effect on yield of winter wheat (ed. Vereijken, P. H.) Ch. 1, 1–3 (Wageningen University, ). For decisions on whether or not to spray insecticides to prevent aphid feeding damage, crops should be checked from late tillering onwards for oat aphids on stems, undersides of leaves and ears and for corn aphids in the furled growing tips.

Walk through the crop in a 'W' pattern, noting the numbers of aphids per tiller at every few paces. to thousands of aphids on a plant in a few weeks. Aphid numbers can build until conditions are so crowded, or the plant is so stressed, that winged fo rms a re produced.

These win ged fo rms f ly off in search of new hosts and the process is repeated. CON TROL Early d ete ction is th ky to reduing aphid infestations. The flght of wged colonizers. English grain aphid (EGA) appears in cereals, especially wheat, as grain begins to fill.

Historically they have been reported as causing economic loss at 25 aphids per grain head. Newer estimates of EGA damage occur at 50aphids per tiller before and during the milk stage of grain fill.

After the soft dough stage no economic loss occurs. El-Fatih () stated that R. maidis was the most abundant aphid species while the other cereal aphid species were found in few numbers over two seasons at Middle Egypt.

Highest records of aphids’ population were found at the plant age of 70 days. Similar to the Aphid Advisor app for soybean aphids, the free Cereal Aphid Manager app developed by AAFC helps to determine if the number of beneficial insects you have will do the control for you, or whether there are too few and an insecticide application is required.

The app is available both at Google Play and the Apple Store.1. Aphids. Aphids are very small soft green insects which feed on cereals and many other types of plants and can cause considerable damage. The cereal aphids feed by sucking plant juices which may reduce yield by directly weakening the plant.