Showing papers on "Aphid published in 1978"

The numbers and distribution of subterranean aphids and their exploitation by the ant Lasius flavus (Fabr.)

Abstract: . 1. Subterranean aphids in old pasture were found to show extremely clumped distributions with about 3000 aphids (omitting first instars) per ant nest throughout the year. 2. They were generally distributed in and away from the nest mounds, but within the ant's foraging territories. 3. At summer temperatures, more than 3000 first instars are lost from the aphid population per ant nest per day and it is concluded that these are eaten by the ants in addition to some older aphids and the honeydew produced. 4. The aphids may therefore provide enough food to maintain the ants with very little extra needed in the form of other prey.

Adaptation of alarm pheromone responses of the pea aphid Acyrthosiphon pisum (Harris)

Abstract: Adult and fourth-instar pea aphids from Vancouver, B.C., responded to alarm pheromone by either dropping, running, or backing up. Younger instars showed almost no response to pheromone but all instars responded to a pheromone–vibratory stimulus, usually by dropping. We suggest that younger instars respond conservatively to alarm pheromone because they are less agile on the ground and are more likely to die there before finding a suitable food plant. Adult and fourth-instar aphids from the hot, dry region of British Columbia do not respond to alarm pheromone by dropping. This is due to the high risk associated with any instar leaving the host plant where ground temperatures and evaporation rates are high.Clones of aphids contained both individuals which do and do not drop in response to pheromone stimulus. This mixture of behaviour types allows part of the group to exploit new resources while others remain on a known resource.

The detection and distribution of organophosphorus and carbamate insecticide-resistant Myzus persicae (Sulz.) in Britain in 1976

Abstract: Examination of the enzyme that determines the level of resistance to organophosphorus insecticides and carbamates in Myzus persicae (Sulz.) and bioassays were used to establish the frequency and resistance levels of resistant aphids on outdoor crops in Britain in 1976. The biochemical tests, staining esterase-4 after electrophoresis and total esterase determination, were more sensitive than bioassays. However the dip-test, a simple, rapid and inexpensive bioassay designed to detect resistance and its different levels gave satisfactory results which warrant its use where biochemical detection of resistance is not possible. Carboxylesterase activities of M. persicae collected in 1976 fell into three groups: low, moderate and high, and these were correlated with differences in tolerance to dimethoate, demeton-S-methyl and pirimicarb. Aphids with low esterase activity were susceptible(S). Those with the moderately active enzyme (R1) had five- to seven-fold resistance to the two organophosphorus insecticides and were marginally resistant (about two-fold) to pirimicarb. The insects with the most active esterase (R2) were strongly resistant to dimethoate (resistance factor, RF × 126) and moderately resistant to demeton-S-methyl (RF × 17) and pirimicarb (RF × 8). Some R1, but no S aphids survived the recommended dose of demeton-S-methyl on field crops probably because they were under the lowest leaves and therefore protected from direct contact with the spray. Laboratory tests demonstrated that these R1 aphids tolerated the residual deposit and systemic dose present in the leaves of the treated potato-plants. This enabled their numbers to recover in treated fields much faster than the susceptible insects which could do so by immigration only when the residual dose in the plant was no longer toxic. R1 aphids were common throughout the country particularly in eastern England where susceptible aphids were rare, but in the Shardlow area of Derbyshire susceptible aphids were in the majority throughout the summer. R2 aphids were found only in samples from the west of Scotland and northern England. The implications of the presence of aphids with different levels of resistance for aphid control are discussed.

Absence of Genetic Variability in the Green Peach Aphid, Myzus persicae (Hemiptera: Aphididae),

Abstract: An electrophoretic survey of genetic variability in 9 U.S. populations of the green peach aphid, Myzus persicae (Sulzer), revealed zero heterozygosity for 19 structural genes. This was contrasted with an avg heterozygosity of 0.07 for the potato aphid, Macrosiphum euphorbiae (Thomas), which has a similar life history. We propose that this finding reflects a recent, limited introduction of M. persicae, whereas M. euphorbiae is endemic. Several individuals, presumed to be morphologically similar species of Myzus, were detected both in natural and laboratory populations of M. persicae. Putative biotypes of M. persicae may be attributable to colonies derived from several species.

Effects of synthetic lime aphid honeydew on populations of soil organisms

Abstract: The effect of synthetic aphid honeydew on the populations of soil dwelling organisms has been studied in a woodland and a grassland soil. Honeydew sugars were shown to produce different effects in the two soil types. In the woodland soil a 30% increase in fungal population resulted from the application of synthetic honeydew at a rate equivalent to that from a natural aphid population. Peaks of up to a three-fold increase in bacterial numbers also occurred. In the grassland soil no increase in microbial population was evident, but soil respiration was 74% greater in a treated plot than in an untreated plot the day following the sugar amendment. In neither soil were microarthropod populations influenced by the addition of synthetic honeydew.

Effects of feeding position of the aphids Sitobion avenae and Metopolophium dirhodum on wheat yield and quality

Abstract: SUMMARY The effects of feeding site of Sitobion avenae and Metopolophium dirhodum on grain weight, number and nitrogen content were investigated in the laboratory and in the field. When the latter species was confined to particular leaves in a growth room, grain weight reductions occurred only when the aphid fed on the flag leaf; reductions in percentage grain protein, but not grain weight, followed lower leaf feeding. Leaves which had borne aphids had a higher proportion of nitrogen at death than control leaves, but this explained little of the shortfall in grain nitrogen, which was mainly due to direct removal during aphid feeding. Multiple regressions of grain weight on aphid species/feeding site in the field confirmed the lack of grain weight effects when lower leaves were colonised; because grain size was greatly reduced by aphid feeding, percentage grain nitrogen increased with increasing aphid density in one cultivar and in others was unchanged. Successive comparison of control grain weights with those from tillers bearing an increasing range of aphid densities resulted in a significant reduction in weight with tillers bearing 21 to 25 aphid units on their ear and flag leaf combined, one unit comprising one adult or fourth-instar aphid or three of earlier instars. These and other factors affecting the nature and extent of cereal aphid damage are discussed.

Response of susceptible and resistant peach‐potato aphids Myzus persicae (Sulz.) to insecticides in leaf‐dip bioassays

Abstract: The response of susceptible (S), moderately resistant (R1) and strongly resistant (R2) peach-potato aphids, Myzus persicae (Sulz.) to organophosphorus, carbamate and pyrethroid insecticides was tested by a leaf-dip bioassay. The aphids were placed on potato leaves (dipped in insecticide solutions 1–2 or 24 h before infestation) and their mortality examined 48 h later. R1 aphids were virtually susceptible to most of the carbamates, demephion and acephate, but were slightly to moderately resistant (2.1–9.4 times) to permethrin, cypermethrin and (S)-α-cyano-3-phenoxybenzyl (1R)-cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylate (I), (NRDC 161), to 5,6,7,8-tetrahydro-2-methylquinolin-4-yl dimethylcarbamate (II), (Hoechst 25 682) and demeton-S-methyl. R2 aphids resisted more strongly or very strongly (between 65 and 1280 times) the pyrethroids, demeton-S-methyl (×94), II (×83) and demephion (×9), and were slightly to moderately (2–5 times) resistant to acephate, pirimicarb, ethiofencarb and 2-(dimethylcarbamoyloxyimino)-3-methoxyimino-N,N- dimethylbutyramide (III), (DPX 3853). Both resistant strains were susceptible to nitrilacarb [4,4-dimethyl-5-(methylcarbamoyloxyimino)pentanenitrile] complex (1:1) with zinc chloride (IV), (AC 85 258). The implications of these results in terms of practical aphid control are discussed.

Effect of adult Coccinellidae on the spread of a plant virus by an aphid.

Abstract: (1) The influence of adult coccinellids Coccinella californica Mannerheim on the spread of a pea aphid Acyrthosiphon pisum (Harris) transmitted plant virus (Bean Yellow Mosaic Virus) was studied in field cases. (2) Aphids in cages containing adult coccinellids frequently moved among food plants while only four of seventy-four aphids in the coccinellid-free cage left the original plant. (3) New virus infections occurred more often and virus spread further in cages with aphids and coccinellids than in cages with only aphids. (4) The role of predators in the spread of plant viruses by aphids is discussed.

Regulation of the Damson-Hop Aphid (Phorodon Humuli (Schrank)) on Hops (Humulus lupulus L.) by Predators

Abstract: SummaryThe development of Phorodon humuli populations was studied on hops cv Cobbs during 1971 and 1972. Plants not treated with an insecticide in 1971 were completely defoliated by late July. Half of the experimental plants in 1971 and all of the experimental plants in 1972 were treated at the end of June with 120 ml of 1% dimefox. When the effect of the insecticide had diminished, aphid populations increased on plants from which predators were excluded by sleeve-cages, but decreased on uncaged plants and caged controls. At harvest on uncaged strings there were averages of 1 aphid per 10 cones in 1971 and 3 aphids per cone in 1972. Forficula auricularia L., Anthocoris nemorum (L.) and A. nemoralis (F.) were the most abundant predators when aphid populations declined. In 1972 predators (mostly anthocorids) reduced aphid populations on plants from which earwigs (F. auricularia) and non-flying predators were excluded, but more slowly than on controls.

Minimum Acquisition and Transmission times for Potato Leaf Roll Virus by the Green Peach Aphid

Abstract: The times required for acquisition and transmission of potato leaf roll virus (PLRV), Corium solani Holmes, and for phloem penetration by individual green peach aphids, Myzus persicae (Sulzer), were examined using an electronic monitoring system (EMS). Individual aphids, recorded on the EMS, were transferred from PLRV infected plants to indicator plants after feeding for specific amounts of time. The indicator plants, Physalis pubescens L. and potato, Solanum tuberosum L. var. Russet Burbank, were observed for the expression of PLRV symptoms in the following weeks. The minimum acquisition feeding time was 1.6 min and the minimum transmission feeding time was 2.5 min. The results show a direct relationship between the duration of acquisition feeding time and the probability of aphid infectivity and pathogenicity The data do not show a marked increase in the incidence of PLRV with increasing transmission times. Phloem feeding often occurred in less than 5 min after aphids were placed on plants.

Quality and Quantity of Plant Sap Available to the Pea Aphid

Abstract: Pea phloem sap was collected from excised pea aphid stylets and analysed chemically. The only sugar found was sucrose, at an average concentration of 5.6±0.82% w/w. Total amino acid content was 4.5% w/w, 98.9% as free amino acid. Phloem sap of young pea plants apparently has lower sugar content and higher total amino acid content than woody perennials and most other herbs. These amounts may be related to the developmental stage of the pea plants and may change with age. Average rate of exudation from cut stylets was 0.41 mm3/h. At this rate, total potential energy available to an adult aphid is 4.6 cal/day. Pressure within the plant necessary to force sap through the stylets at this rate was calculated to be 16 atm.

Analysis of effects of the bird cherry-oat aphid on the growth of barley: unrestricted infestation

Abstract: SUMMARY Infestation with the bird cherry-oat aphid considerably reduced the dry weight yield, the leaf area, the number of tillers and the number of leaves of barley plants. Growth analysis revealed that the major effect of infestation was to reduce unit leaf rate. However, infested plants compensated partially for this by allocating a greater proportion of their dry weight to the production of leaf laminae than did the control plants. Rates of net photosynthesis in individual, attached leaves were measured using the carbon dioxide exchange method; infested and control plants were found to have very similar rates of photosynthesis. Thus the reduction of unit leaf rate did not result from an effect of photosynthesis. It is suggested that the decreased growth of the barley plants is explicable in terms of cumulative assimilate loss due to aphid feeding.

Trophic regulation of postdiapause ovariole maturation inCoccinella septempunctata [Col.: Coccinellidae]

Abstract: In 1977 the vernal maturation ofCoccinella septempunctata L. females was investigated in relation to the variation in aphid population density on alfalfa and cereals in central Bohemia. The ovarioles do not ripen unless the aphid population density reaches a certain threshold. This leads to considerable variability in the time of vernal reproductive activity (up to 1.5 months in the same geographic locality) among subpopulations living on crops with different aphid densities. This mechanism enables the reproduction of the aphidophagous insect to synchronize with the population development of the aphid.

The effect of trans-\-farnesene, used as a repellant against landing aphid alatae in seed potato growing

Abstract: Periodical application of trans-\-farnesene, incorporated in polyvinylchloride from which it was slowly and regularly released, did not measurably inhibit the infection of seed-potato-plots with PVYN by aphid alatae. The progeny of PVYN-infected hills proved to be only partially infected with the disease.

Observations of an aphid infestation on hawthorn in the vicinity of a motorway

Abstract: a 8 gg of a mixture of i or 1':3:4:5=30:40:15:15 in 0.1 ml of heptane applied to 60/80 Chromosorb W : insects were counted after 1 h not seem possible that the small amount of (+)isomer in our ( ) -grandisol would support full activity. From this bioassay, it is deduced that both of the grandisol isomers are fully active, although there might be a slight preference for the (+) isomer. This lack of chiral specificity in the pheromone receptor of boll weevil is in sharp contrast with the strong specificity among other insects, Dendroctonus brevicomis [6], Ips grandicollis [7], Ips calligraphus [8] and Porthetria dispar [8, 9], etc. Synthesis of other chiral pheromones will be further pursued to increase our knowledge of the chirality-pheromone activity relationship.

Response of Selected Predator Species to Different Densities of Aphis gossypii and Heliothis virescens Eggs

Abstract: Four species of predators were each exposed to different densities of tobacco budworm, Heliothis virescens (F.), eggs in the presence or absence of the cotton aphid, Aphis gossypii Glover. When alternate prey (aphids) were absent, the functional response of most predators was usually directly proportional to the density, of Heliothis eggs. Under these conditions larvae of Hippodamia convergens Guerin-Meneville were the most effective predators, followed by adult lady beetles, Chrysopa carnea Stephens larvae, adult Geocoris punctipes (Say), and Orius insidiosus (Say), respectively. Among all predators except G. punctipes , total percentage consumption of Heliothis eggs was reduced when aphids were available as alternate prey. Geocoris and Hippodamia adults were least affected by the presence of aphids while Chrysopa and Hippodamia larvae were most affected. Interactions among the species were generally of a density-dependent nature.

Relations of carrot red leaf and carrot mottle viruses with their aphid vector, Cavariella aegopodii

Abstract: SUMMARY Studies with Scottish isolates of carrot red leaf (CRLV) and carrot mottle (CMotV) viruses confirmed the dependency of CMotV on CRLV for transmission by the aphid Cavariella aegopodii. CMotV was transmitted by aphids only when the two viruses were present in the same source plant, and its transmission was not assisted by anthriscus yellows virus, which acts as a helper for parsnip yellow fleck virus. Some test plants became infected with CRLV alone, and a few with CMotV alone. In winter, aphid transmission of CRLV and CMotV was greatly increased when the source plants received supplementary lighting whereas the CMotV infectivity of sap was not increased. C. aegopodii acquired CRLV and CMotV after minimum acquisition access times of 30 min and inoculated them after minimum inoculation access times of 2 min. There was a minimum latent period of 7–18 h. The viruses were retained by the aphid after moulting and are therefore circulative in the vector, but were not transmitted to progeny insects. Aphids allowed 24 h to acquire the viruses continued to transmit them for at least 12 days, but some aphids allowed 6 h or less for virus acquisition ceased to transmit after 3 or 4 days. CRLV is considered a tentative member of the luteovirus group.

A weather index to forecast potential incidence of aphid-transmitted virus diseases of peppers in the niagara peninsula

Abstract: The incidence of non-persistent aphid-transmitted viruses of peppers in the Niagara Peninsula at the end of August was closely correlated with accumulated degree-days plus total bright sunshine hours in April. Virus disease incidence agreed closely with predictions from a simple regression equation based on these weather factors for the period 1970–1977. Risk years for these diseases can be accurately forecast for this region in advance of spring planting. This model may prove generally applicable in other pepper growing areas by calculating regression of local virus incidence on regional meteorological records.

Measurements of the osmotic concentrations of stylet sap, haemolymph and honeydew from an aphid under osmotic stress

Abstract: The osmoregulatory physiology of aphids is poorly understood, yet it is such small terrestrial insects that face the severest osmotic problems. The lack of progress in this field reflects not only the difficulty of working with insects of such a small size but aUo the difficulty of obtaining samples of the sap on which they feed. The present investigation describes the successful osmoregulation of the aphid Myzus persicae cultured on a sea water plant. The aphid ingests phloem sap which is several times more osmotically concentrated than its haemolymph. Together with its small size this represents a severe challenge to its osmoregulatory ability. A second aim of the paper is to describe a method for the collection of the excreted fluid (honeydew) which avoids the systematic errors which inevitably result from the methods previously used to attempt such collection. Apterous Myzus persicae were cultured on sea aster, Aster tripolium, grown from seed and watered with a nutrient (modified Hoagland's) solution. To provide freshwater conditions the Hoagland's solution was made up using distilled water, while for sea water conditions, the nutrients were added to full strength artificial sea water (New Tropic Marin). Osmotic pressures, as indicated by depression of freezing point, were measured using a Clifton Technical Physics nanolitre osmometer. All osmotic pressure determinations were carried out within 30 min of collection, with the sample being frozen only once. Aphid stylets were cut and sap collected using the radio probe, methods, and precautions described in Downing & Unwin (1977). The technique involves severing the mouthparts of a feeding aphid using a high frequency (150 MHz) probe and then collecting, under oil, the sap exuding from the cut stylets which remain embedded in the plant. Very large increases in osmotic concentration result if the sap is not protected from contact with the air or if the sap is allowed to touch the surface of the leaf. Blood was collected from individual aphids under oil by cutting either front leg and allowing the haemolymph to exude into the oil. A possible source of error is that the disturbance to the aphid might result in a change in the osmotic concentration of its haemolymph. Measurements on adult aphids removed from a plant and left under r>il for varying periods showed that no changes occurred within 1-4 min (mean = 348

Resistance of Tobacco Introduction 1112 to the Tobacco Budworm and Green Peach Aphid

Abstract: In field and laboratory tests, the mechanism of resistance to the tobacco budworm, Heliothis virescens (F.), in tobacco introduction (T.I.) 1112 (Nicotiana tabacum L.)was found to be nonpreference for oviposition. The mechanism of resistance to the green peach aphid, Myzus persicae (Sulzer), appeared to be a tendency for alate aphids to abandon T.I. 1112 more readily than fluecured tobacco. Trichogramma parasitized Heliothis eggs on T.I. 1112, and more coccinelids werc present on this line than on flue-cured tobacco. Nonglandular trichomes may contribute to the observed resistance.

Dispersal and Recolonization by Myzus persicae following Aphid Alarm Pheromone Exposure

Abstract: Aphids disperse from plant surfaces immediately after exposure to alarm pheromone, but they return to approximately their original levels by 1 h following exposure. Thus, the effect is a short-term one.

The influence of repellent materials and aphid extracts on settling behaviour and larviposition of Myzus persicae (Suizer) (Hemiptera: Aphididae)

Abstract: When incorporated into an artificial diet or painted on the surface of the membrane containing the diet, solutions of the insect repellent GD 880 (2-methyl-2-(octylamino)-1-propanol) killed aphids, whilst extracts of neem seeds (Azadirachta indica) or extracts of the bodies ofMyzus persicae (Sulz.) deterred settling and larviposition of apterous adults. The deterrent effect occurred even when the painted membrane was covered by a similar but untreated membrane. When applied in culture solutions to the roots of young kale plants, GD 880 and extracts of neem influenced aphids on the foliage only at concentrations that visibly affected plant growth, but neem extract (and to a lesser extent GD 880) decreased aphid colonisation when painted on kale leaves at non-damaging concentrations.

Predator Complex of the Green Peach Aphid on Sugarbeets: Expansion of the Predator Power and Efficacy Model

Abstract: A model to evaluate potential reductive impact of populations of green peach aphid, Myzus persicae (Sulzer), by predators was generalized to include effects of temperature on the rate of aphid reproduction and the functional response of the predator complex. Coccinella transversoguttata richardsoni Brown was the most abundant predator in field experiments with large numbers of green peach aphids on sugarbeet plants, Beta vulgaris , L., Geocoris pallens Stal, syrphids, and Scymnus marginicollis Mannerheim were also abundant. Predators had a major role in determining the abundance of aphids, but their effect was greater at the higher densities because the more voracious species responded preferentially to high aphid populations.

Further records of aphid parasitoids (Hymenoptera : Aphidiidae) from Meghalaya, India

Abstract: Further records on parasitoids reared from various aphid species in Meghalaya arc reviewed. Trioxys (Dinodoxys) shillongensis Stary, sp. nov., is described. Host-Parasitoid list is added.

Distribution and Characteristics of Balsam Woolly Aphid Infestations in the Great Smoky Mountains

Abstract: The balsam woolly aphid was inadvertently introduced into North America in Maine around 1900 and has subsequently spread throughout the eastern spruce-fir forests. Within the past 20 years the aphid has become a serious pest of Fraser fir in the Southern Appalachians, causing concern for the scenic and scientific resources of the spruce-fir forests. Fraser fir is highly susceptible to attack by the aphid with mortality occurring within 2 to 5 years following colonization. This rapid mortality in combination with the phenomenal reproductive potential of the aphid threatens the existence of Fraser fir. Investigations were conducted within the Great Smoky Mountains National Park to determine the history, current distribution, and level of damage of balsam woolly aphid investations. The relationship of levels of infestations with selected community structure and environmental factors was also investigated. The balsam woolly aphid arrived in the Great Smoky Mountains around 1960. The initial infestation was on Mt. Sterling, located on the eastern boundary of the spruce-fir distribution within the Park. Analysis of the aerial infrared transparencies revealed that the aphid is distributed throughout the entire spruce-fir forest type. Infestation intensity, as determined by the extent of fir mortality and the size of the infestation, was highest in the eastern portion of the spruce-fir distribution, lower in the middle portion, and lowest in the western portion. Detailed information of the location and size of infestations was recorded on 1:24000 topographic maps. Permanent plots were located throughout the spruce-fir forests in the Park in areas of varying infestation levels. Sampling was proportional

Aphid-injection experiments with carrot mottle virus and its helper virus, carrot red leaf.

Abstract: SUMMARY Carrot mottle virus (CMotV) and its helper virus, carrot red leaf (CRLV), were not transmitted by aphids (Cavariella aegopodii) that had fed through membranes on, or had been injected with, sap from mixedly infected chervil plants or partially purified preparations of CMotV. However, the viruses were transmitted by recipient aphids injected with haemolymph from donor aphids that had fed on mixedly infected plants but not by a second series of recipients injected with haemolymph from the first series. Some of the first series of recipients transmitted both viruses for up to 11 days but others transmitted erratically and many lost ability to transmit after a few days. The results confirm that both viruses are circulative but provide no evidence for multiplication in the vector. Non-viruliferous aphids, or aphids that had acquired CRLV by feeding, did not transmit CMotV when they were injected with haemolymph from aphids that had fed on a source of CMotV alone, confirming that they can only transmit CMotV when they acquire it from a mixedly infected plant. When extracts from donor aphids were treated with ether before injection, recipient aphids transmitted both CRLV and CMotV, although the infectivity of CMotV grown in Nicotiana clevelandii in the absence of CRLV is destroyed by ether treatment. CMotV particles acquired by aphids from mixedly infected plants therefore differed in some way from those in singly infected plants. A plausible explanation of these results, and of the dependence of CMotV on CRLV for aphid transmission, is that doubly infected plants contain some particles that consist of CMotV nucleic acid coated with CRLV protein.