Showing papers on "Aphid published in 1977"

Aphid ecology: life-cycles, polymorphism, and population regulation.

Abstract: Aphids are plant sucking bugs which occur throughout the world. The greatest number of species are in the temperate regions, where few higher plants are free from aphids. They differ from other plant sucking bugs of the Aphidoidea in that the females of at least a few generations are parthenogenetic and viviparous. Although many species are small and inconspicuous, they frequently become abundant. As many as 2000 million per acre (0.4 ha) may live on the above-ground parts of plants, and the roots may support a further 260 million (46, 92, 117, 148). Aphids, like many other insects, are capable of migrating great distances (up to 1300 km) by means of wind (25, 48, 70). Polymorphism is characteristic of aphids. Asexual aphids of some species can either possess wings (in which case they are termed alatae), or lack wings (these morphs are called apterae). Typically there are several structurally different morphs in a species, including both sexual and asexual forms.

Chapter 1 – worldwide importance of aphids as virus vectors

Abstract: Publisher Summary This chapter discusses the importance of Aphids as virus vectors. Aphid transmitted viruses, like aphids, may kill infected plants or affect a crop so badly that it is not worth harvesting. Later infections may reduce yields by smaller amounts. The probability of a virus being transmitted from any one individual plant to another depends on many factors other than the taxonomic position of the two plants concerned and that of the potential vector. The proximity of the plants, the feeding sites, activity and other behavior of the aphid, environmental conditions such as weather, and the presence of other organisms including other viruses, other aphids, ants, and natural enemies may all affect transmission. Many of these factors interact continuously with one another. This chapter discusses the aspects of the taxonomy, biology, and zoogeography that affect the ability of aphids to transmit virus diseases of plants. It is the interaction of these intrinsic features of aphids with environmental factors such as weather and the intrinsic properties of plants that constitute population ecology and that together with the intrinsic properties of viruses and agricultural practice determine the epidemiology of plant virus diseases. Each subfamily of Aphididae has its own characteristic biology. The Adelgidae and Phylloxeridae differ from the Aphididae not only in morphology but also in that the parthenogenetic females are oviparous and not viviparous. All aphids produce a number of short-lived generations every year and not more than one of these generations reproduces sexually as the sexual generation gives rise to the overwintering eggs.

Some effects of dimethoate on arthropods in winter wheat

Abstract: SUMMARY The application of dimethoate to winter wheat to control cereal aphids caused changes in the numbers of the non-target arthropod fauna. The total number of non-target arthropods in the treated area was 15% of that in the untreated area 7 days after treatment and 40% after 2 weeks. There were still differences in both the equitability of phytophagous species and the diversity of predatory species two months after treatment. Adults and the immature stages of many arthropod predators were reduced; for example, Araneae were reduced by 90% 7 days after treatment and predatory Carabidae by 76% -during the 6-week-period after treatment. Many dead adult and larval Coccinellidae and Syrphidae were found in the field after treatment. Chrysopa carnea (Chrysopidae) appeared to be the most resistant 'aphid specific' species. The widespread use of insecticides, such as dimethoate, on cereal crops could possibly exacerbate pest problems, not only in cereals but also in other crops.

Reproductive strategy of winged and wingless morphs of the aphids Sitobion avenae and Metopolophium dirhodum.

Abstract: The reproduction of apterous and alate morphs of the aphids Sitobion avenae and Metopolophium dirhodum is compared on the basis of fecundity in 5- and 10-day periods of adult life. Apterae of both species are consistently more fecund than alatae of comparable weight, producing about three more nymphs on average in any 5-day period. The reproductive differences are related to the number and quality of embryos at eclosion and to ovulation rates, both of which in turn appear to be linked to wing-muscle maintenance. These relationships between weight, embryos and reproduction may be used to predict a newly moulted adult aphid's fecundity, a method which may facilitate the assessment of resistance to aphids in new cereal varieties, by obviating lengthy recording of reproduction. The strategies by which alatae of these and other aphid species minimize the difference between their fecundity and that of apterae are discussed.

Effects of Mineral Oil on Probing Behavior and Transmission of Stylet-borne Viruses by Myzus persicae

Abstract: Electronic monitoring of probing, salivation, and feeding of Myzus persicae (Sulzer) adults on pepper leaves, Capsicum annum L., variety ‘California Wonder,’ after treatment with an 0.75% emulsion of Sunoco 7E oil revealed significant increases in preprobing time over aphids on untreated leaves, little effect on salivation, and fewer aphids ingested sap after contacting oil coated leaves. The antitransmission activity of oil was associated with oil located over the anticlinal walls of epidermal cells. This activity could be removed by absorptive dusts applied to oil treated leaves. Studies on the influence of temperature or expansion of leaf surfaces on persistence of activity of oil showed that rate of loss of activity is greater at 32° than at 24° and 16°C, and expansion of leaf areas up to 150% does not significantly reduce the effectiveness of the oil over a 6-day period following application. Young leaves treated with oil were more susceptible to infection with potato virus (PVY) than were mature leaves. Oil affected aphid transmission of a normally vectorless strain of tobacco etch virus much the same as it did an efficiently vectored strain of PVY. Previous work on effects of oil against both acquisition and inoculation of virus by aphids was verified. Protection of a leaf was limited to the surface on which oil was applied. Momentary contact between an aphid’s labium and an oil treated leaf sufficed to reduce transmission. The anti-transmission effect also resulted from a momentary contact between the labium and a surface impermeable to stylet penetration. Oil can be removed from the aphid’s labium by absorption on cellulose.

Reproduction and population growth of the pea aphid (homoptera: aphididae) under laboratory and field conditions

Abstract: The effect of temperature on the age-specific fecundity and the survival of apterous and alate virginoparous pea aphid, Acyrthosiphon pisum (Harris), from Kamloops, B.C., was measured. Demographic statistics were estimated for 10.3°, 14.8°, 19.7°, 26.1°, and 27.8°C constant and for fluctuating field temperatures. On a 24-h-day time-scale, temperature and longevity were inversely related in both morphs; total fecundity was highest at average and low constant temperatures. On a physiological time-scale, the intrinsic rate of increase (rm) was insensitive to changes in constant temperature in the range between 10° and 20°C; temperatures above 25°C were detrimental to aphid population growth and survival. Alate virginoparae generally had a longer pre-reproductive period and achieved a lower mean total fecundity than apterae maintained under identical conditions. The usefulness of laboratory measurements for the prediction of population growth under variable field temperatures is discussed. Differences in the reproductive patterns of alate and apterous pea aphids are considered in the context of the r- and K-hypothesis of selection.

The Biology and Main Causes of Changes in Numbers of the Rose Aphid, Macrosiphum rosae (L.), on Cultivated Roses in South Australia

Abstract: In South Australia, M. rosae is anholocyclic on Rosa, reproducing parthenogentically and viviparously all year round. It feeds mainly on the young leaves and developing flower-buds of hybrid tea roses. The fate of a colony of aphids on a single bud is a function of temperature, rainfall, predation, the time for which the bud remains favourable for the aphids, and the influence of crowding on alatiform production and on dispersal of apterae by walking or dropping off. The numbers of aphids on cultivated hybrid tea roses in a rose garden had three peaks in spring-summer which coincided with three flushes of growth of the rose. The first peak, in spring, was the highest; thereafter numbers of aphids were relatively low, mainly because of predation by three species of native predators, namely the hemerobiid Micromus tasmaniae, the syrphid Melangyna viridiceps and the ladybird Leis conformis. The study was a prelude to computer simulation of the population dynamics of the aphid which will be used to investigate the problem of the regulation of density in natural populations of aphids.

Assessment of methods for testing varietal resistance to aphid s in cereals

Abstract: SUMMARY The adult weight of three species of cereal aphids on barley was correlated with the number of large embryos and the total number of embryos within newly moulted adults. The relationships between embryo number and weight were constant for each species of aphid on all seven varieties of barley under identical conditions. The weights of aphids of each species on seven varieties of barley were significantly different from each other in each experiment. Pot size and plant age had a significant effect on the weights of Rhopalosiphum padi. The validity of these tests compared with previous methods is discussed.

Breeding plants for resistance to aphid infestation

Abstract: This chapter discusses the breeding of plants for resistance to aphid infestation. Aphids damage crops both directly by their feeding and by spreading viruses, and the relative importance of each has often been a source of friendly disagreement between entomologists and virologists. A single viruliferous aphid can, by infecting a plant, cause as much damage in one feed as is done during prolonged feeding by several non-viruliferous aphids, especially if the plant is very young. There is apparently tremendous potential for restricting virus spread by breeding aphid-resistant cultivars, but the realization of this potential depends on understanding how the plant host, aphid, and virus interact. Tolerance to large aphid populations may prevent aphid damage but not restrict virus spread. Increased mobility of aphids caused by host characters such as a repellent or poor nutritional status may provoke dispersal with consequent virus spread. Infestation by aphids and the subsequent infection of a crop by virus is a dynamic process that can be hampered, diverted, or stopped at various stages. There is opportunity to use accumulated knowledge to change the balance in the plant's favor and this requires the collaboration of various disciplines concerned with increasing agricultural output.

Biology of the corn leaf aphid, rhopalosiphum maidis (homoptera: aphididae), in southwestern ontario

Abstract: There was no evidence that the corn leaf aphid, Rhopalosiphum maidis (Fitch), can overwinter in southwestern Ontario. An alate with a small colony of nymphs was found on 26 April, indicating that migration from the south starts early in the spring. Early migrants colonized winter barley, but not winter oats, rye, or wheat. Colonization on field corn did not occur until over a month after plant emergence. Only small numbers of alatae initiated infestations on corn and the large variation in size of aphid infestations observed at pollination was due to differences in the longevity and fecundity of these few early attackers. The whorl leaves which enclosed the tassel before pollination provided a very favorable environment for rapid development of the aphids. Trapping of alatae in yellow pans of water at the periphery of a corn field in the fall showed that a minimum temperature of 13°C was required for flight. At a constant temperature of 25.5°C and a light:dark photoperiod of 14:10 h, the average prereproductive, reproductive, and postreproductive periods for 29 aphids were 5.9, 15.8, and 9.6 days, respectively. The average number of nymphs produced/female was 68.2.

Oils and other inhibitors of nonpersistent virus transmission

Abstract: Publisher Summary This chapter discusses the ways in which oils inhibit the aphid transmission of nonpersistent and semipersistent viruses. It also discusses the limits of efficiency of oil treatments according to the properties of the oil used and the possibilities of using oils for the control of stylet-borne viruses in the field. About 250 aphid species tested to date as vectors of plant viruses represent only about 9% of the known species. Oil-induced inhibition of the transmission of bean yellow mosaic virus by Acyrtosiphon onobrychis and of beet yellows virus by Aphis fabae showed that oil inhibits the transmission of viruses by several species of aphid vector. Therefore, it seems likely that oil inhibition may be expected for all vectors of a given nonpersistent virus. The rate of inhibition by oil is reduced when the number of aphids on the test plants is increased. Increasing oil concentration of the emulsion restored the inhibiting effect even with large numbers of aphids per plant. Progress has been accomplished in the control of aphid transmission of stylet-borne viruses, especially using two new techniques, namely, oil sprays and reflective surfaces. Both techniques are able to inhibit the field spread of stylet-borne viruses by aphids.

Chapter 13 – membrane feeding systems in aphid research

Abstract: Publisher Summary This chapter discusses the membrane feeding systems in aphid research. The membrane feeding system allows for separation of host plant and aphid for short or long periods. In this way, one can handle aphids more easily, in less space, and under more controlled climatological and physiological experimental conditions. Therefore, one can determine food uptake, excretion, resorption, oxygen consumption, etc. during feeding. Various insecticide and virus transmission studies can be managed with a membrane feeding system. The system is also handy for observing the processes of salivation and egestion. For many problems in virology, successive aphid generations are not required. However, in some cases, aphid physiology may be modified in regard to salivation, food uptake, excretion, and egestion. A virologist might be interested in switching aphids back and forth from plant to diet. Knowledge regarding this type of transfer is limited. Therefore, one should distinguish carefully between aphids transferred from plant to diet and those that are already adapted to the latter for a day or longer. Adaptation phenomena are already known within a range of different host plants. The membrane feeding behavior of M. persicae is mainly based on observations of newly born larvae. Newly born larvae are more transparent than later instars. In addition, they place the labium at a more acute angle, thus bringing the head capsule closer to the membrane surface.

Aphid Alarm Pheromones: Dispersion of Hyadaphis erysimi and Myzus persicae,

Abstract: Clusters of the turnip aphid, Hyadaphis erysimi (Kaltenbach), and green peach aphid, Myzus persicae (Sulzer), feeding on turnip leaves, were exposed to alarm pheromone from cornicle droplets. Aphids dispersed by walking or falling, both responses occurring about equally. The proportion of aphids dispersing by falling decreased with increase in distance of the pheromone source. Aphids that responded to pheromone by walking usually resettled on the same leaf. Redistribution of aphids to other leaves on the plant was attributable almost entirely to the return of aphids which had fallen off the host plant. No preference was exhibited by returning aphids for or against the leaf on which the cluster was originally located.

Notes on the taxonomy and nomenclature ofAphidius species [Hym.: aphidiidae] parasitic on the pea aphid in North America

Abstract: A brief discussion is given on the taxonomy, nomenclature, distribution, and hosts of severalAphidius species attacking the pea aphid,Acyrthosiphon pisum (Harris), in North America.Aphidius pisivorusSmith,A. smithi S. & S. R., andA. erviHal. are considered distinct species attacking the pea aphid;A. nigripesAshm. is shown not to be a parasite of the pea aphid;A. pulcherBaker is placed in synonymy withA. nigripes. Distinguishing characters for each species are illustrated.

Interaction of Fusarium Root Rot with Pea Aphid and Potato Leafhopper Feeding on Forage Legumes

Abstract: LEATH, K. T., and R. A. BYERS. 1977. Interaction of Fusarium root rot with pea aphid and potato leafhopper feeding on foratge legumes. Phytopathology 67: 226-229. The development of root rot caused by Fusarium roseum inoculated with F. oxysporum was reduced significantly was determined in alfalfa and red and white clover grown whenever the plants were subjected to aphid feeding. with and without stress caused by feeding of pea aphids Significantly more plarts died after subjection to the (Acyrthosiphon pisum) on the foliage. Significantly more combined stress of feeding by potato leafhoppers (Empoasca root rot developed in all forage species whenever plants were fabae), root inoculations with F. roseum, and exposure to subjected to aphid feeding. Longevity of red clover plants winter conditions. with roots inoculated with F. roseum and of alfalfa plants Additional key words: Trifolium pratense, Trifolium repens, Medicago sativa, plant stress. Fusarium root and crown rot which is caused by several cm at the start of each test. Cages used in the greenhouse Fusarium species is a chronic disease problem afflicting were of wood frame-plastic screen construction, and each red clover, alfalfa, and other forage legumes. The fungi held 30 plants. Plexiglass tubular cages previously colonize roots shortly after seeding (8), but usually do not described (7) were used to cage individual plants in the cause severe rot until the plant is under stress from some growth chamber. Insects used to stress the plants were the other agent (6, 8), for example increased levels of foliar pea aphid [Acyrthosiphon pisum (Harris)] on all plant disease (8). Similar relationships have been shown in red species and the potato leafhopper [Empoasca fabae clover with red clover vein mosaic virus (2) and with (Harris)] on alfalfa. increased frequency of clipping (9). Roots were inoculated by wounding the taproot about One of the most serious stresses that occurs each year 1 cm below the soil surface. This was done with a single on forage legumes grown in the northeastern United cut, about 1 cm long, made longitudinally with a scalpel States is that caused by the feeding of leafhoppers, aphids, through the cortex. Two milliliters of a fungal suspension weevils, spittlebugs, and plant bugs. Insect feeding were pipetted over the wounded area and the soil was essentially is continuous from spring growth until autumn replaced. Roots of control and aphid-infested plants also frost. The interaction of leaf and stem feeding injury by were wounded. Isolates used were not the same in all tests insects with an increased severity of root rot of forages has and are described with the individual experiments. Fungi not been investigated, were stored in sterile soil between experiments. The objective of the present investigation was to Fresh weights of harvested plant tops were used to evaluate interactions between root rot-causing Fusarium determine the degree of plant stress imposed by the species and insect feeding on the leaves and stems of individual treatments. In the red clover experiment the plants. plants were clipped twice, once duringand again at the end of the test. In other experiments, the plants were MATERIALS AND METHODS clipped only at the end of the test. Aphid counts were made at the end of each experiment (twice during the red General.-All plants were grown singly in a peat-soil clover experiment) to establish the level of aphid activity. mix in 10-cm-diameter clay pots in the greenhouse. Two rating systems based on visual estimation of Before the plants were used in experiments insects were browning were used to evaluate the severity of root rot. controlled by weekly sprays of malathion and The first system included classes 1 through 5 which were oxythioquinox. Plant tops were clipped to a height of 5defined: 1 = no browning; 2 =external browning at wound site; 3 = internal browning at wound site; 4 = internal browning spreading from wound site; and 5 = browning Copyright © 1977 The American Phytopathological Society, 3340 through the complete root and plant dead. The second Pilot Knob Road, St. Paul, MN 55121. All rights reserved, rating system consisted of classes 1 and 2, which were

Effects of pea aphids, acyrthosiphon pisum (homoptera: aphididae), on growth and productivity of pea plants, pisum sativum

Abstract: Feeding by aphids during 11 days decreased plant weight between 4.7% at an initial density of 5 aphids/plant and 63.9% when the infestation began with 50 aphids/plant. At this infestation level, plant surface area was decreased by 54.3% after 10 days. Both soluble carbohydrate and total protein were reduced by aphid feeding but caloric equivalent of pea tissue was not significantly affected. Extraction by aphids of up to 3.5 cal/plant day was offset by a compensatory increase in production by the plant. Extraction of about 32.7 cal/plant day, equivalent to 0.46 adult aphids/cm 2 of plant surface, completely eliminated pea net primary productivity. The relation between energy extracted by aphids, X , and % reduction of plant NPP, Y = 5.54 X −0.058 X 2 −19.17. Aphid consumption affected pea production directly by removing the amount actually ingested and indirectly because of lost production that would have resulted from the consumed material. Maximum sustainable efficiency of utilization of pea NPP by aphids was between 41% and 47% and maximum sustainable efficiency of transfer of pea NPP to aphid biomass was between 20% and 23%. These high utilization and transfer efficiencies probably would be reduced under field conditions by factors which limit aphid numbers.

Population studies ofBrevicoryne brassicae (L.), its parasites and hyperparasites in England

Abstract: Studies on populations ofBrevicoryne brassicae (L.), its parasites and hyperparasites were carried out by actual counting in the sprouts field and by sticky and water traps.B. brassicae was found to be attacked by one primary parasite,Diaretiella rapae (McIntosh), which in turn is parasitized byAlloxysta brassicae (Ashm.),Asaphes vulgarisWalker,A. suspensus (Nees),Pachyneuron minutissimum (Forster) andDendrocerus carpenterii (Curtis). The aphid population in the field was started by immigrant alates which were found flying too early to be synchronized with the sprouts plants. SimilarlyD. rapae was not synchronized with the aphids although many individuals could have been carried into a plot through parasitized immigrant alates, of which less than 30% were found parasitized. Because of high hyperparasitism (especially byA. brassicae)D. rapae was not able to maintain a high rate of parasitism to curb the aphid population growth. The maximum percentage mummies being 27.8%, while the maximum, percentage parasitism being 56.6% recorded only during the early 1974 season (mean=12.9%). The decline of aphid population from September onwards was largely due to the cold weather, Syrphid predation and occasionally fungal attack. The high rate of hyperparasitism byA. brassicae is attributed to its better synchronization withD. rapae. The mean percentage of parasite that emerged from mummies collected during 1973–74 wereD. rapae 31.3%,A. brassicae 64.3%,A. vulgaris andA. suspensus 4.3%,D. carpenterii 0.2% andP. minutissimum 0.1%.

Anatomy of an aphid vector: myzus persicae

Abstract: Publisher Summary This chapter discusses the anatomy of an aphid vector. Anatomical study on aphids reported that the reproductive system of the aphids contains many embryos in various stages of development, that honey-dew does not drop from heaven but is excreted by the aphid from the anus, that aphids possess two chronicles on the posterior dorsal end of the abdomen out of which comes a drop of clear liquid, and that aphids molt four times. The most anterior part of the alimentary tract of an aphid is the food canal of the maxillary stylets. Each half of the salivary gland system of an aphid is composed of the accessory and principal gland. The ducts from both glands join to a single one that runs further to form, together with the contralateral duct, a common salivary duct.. In Myzus persicae, the mesodermal tissue forms a continuous sheet situated in the body cavity against the body wall. It shows three distinct types of cells. Most numerous are the fat cells, characterized by a strong vacuolization of their cytoplasm. The second type of cells are even dispersed individually among the fat cells. They are called basophilic mesodermal cells by their homogeneous basophilic cytoplasm. Mainly distributed along the surface of the mesodermal tissue are the much smaller connective tissue cells.

Preference for and Effect of Greenbug Parasitism and Feeding by Aphelinus asychis

Abstract: The ages of greenbugs, Schizaphis graminum (Rondani), preferred for oviposition and feeding by the parasite Aphelinus asychis (Walker), the percent parasite emergence, aphid age class, and the reproductivity of stung and parasitized aphids were determined under laboratory conditions. Statistical analyses of data were made to study the daily reproductive potential of A. asychis . The parasite's preference was young>middle>old for oviposition and young>old>middle aged aphids for feeding. Elapsed time from oviposition to emergence of parasites was usually 11–12 days for all age groups of aphids with males usually the 1st to emerge. Success in parasite oviposition generally decreased as the age of the aphid increased. No aphid progeny was produced if they were parasitized during the 1st 3 days of their lives. Aphids which were parasitized when they became older showed a significant decrease in reproduction. Stung unparasitized aphids reproduced at a rate similar to unstung aphids.

Aldicarb and Thiofanox: Effect on the Feeding Activity of Green Peach Aphids

Abstract: Aldicarb killed 26% and thiofanox killed 64% of Myzus Persicae (Sulzer) exposed once to potato plants treated with these systemic insecticides Six serial exposures to aldicarb and 3 to thiofanox were required to achieve 98% mortality From the information obtained when using an electronic system to record the probing and feeding of the aphids, neither insecticide can be expected to prevent a mature viruliferous green peach aphid from transmitting potato leaf roll virus to at least one plant, even though both materials will prevent reproduction and virus spread during the early part of the growing season

Resistance to the aphid-borne viruses in the potato

Abstract: Publisher Summary This chapter discusses the resistance to the aphid-borne viruses in potatoes. The potato is an ideal subject for study of resistance to disease. Breeding of potatoes is a slow process. Some cultivars with high resistance to certain viruses are possibly ahead of their time and may fail for some specific weakness or lack of overall suitability. Potato virologists have long been aware that while inoculation of young plants of susceptible cultivars will almost invariably result in infection of the tubers, inoculation of older plants is less likely to do so. There is recent evidence suggesting that the condition occurs during a specific, brief, time interval in the maturation of the plant. Mature-plant resistance can have special significance in combating aphid-borne viruses. Potato cultivars differ in their acceptability to aphids to the point where resistance to the vector has been suggested as a possible means of limiting virus spread. Plant resistance to the aphid per se does not seem to help in controlling the well known potato viruses. It appears that alfalfa mosaic virus might infect potatoes more frequently, given the appropriate vector migration.

Chapter 22 – aphid pheromones

Abstract: Publisher Summary This chapter discusses aphid pheromones and their use to reduce the spread of aphid-borne plant viruses. Aphid pheromones are known to elicit responses in species other than that of the emitting individual. The terms allomone and kairomone have been proposed to deal with interspecific chemical communication. An allomone is defined as a chemical substance produced or acquired by an organism that, when it contacts an individual of another species, evokes in the receiver a behavioral or physiological reaction favorable to the emitter. A kairomone is a chemical messenger that adaptively benefits the receiver. Aphids are seldom found distributed evenly over their host plants. They are usually found clustered together on certain parts of their hosts. Such clustering is often a result of young not dispersing from their viviparous mothers. Dense nymphal aggregates are observed around a mother or sometimes even around a grandmother in aphids such as Brevicoryne brassicae (L). The degree of the gregarious habit varies among species. Aphids of certain genera are highly gregarious whereas others disperse fairly rapidly from their clusters. A number of advantages have been attributed to the gregarious habit of aphids. It is well known that most aphid species prefer to feed on young succulent growth or senescing leaves that presumably offer aphids optimal nutrients for growth and development.