Showing papers on "Aphid published in 1975"

The nature of the effects of the aphids Sitobion avenae and Metopolophium dirhodum on the growth of wheat

Abstract: SUMMARY Field-caged, post-anthesis populations of the aphids Sitobion avenae and Metopolophium dirhodum reduced grain weight of wheat by 14 and 7% respectively and induced changes in the senescence of the flag leaf. Spikelet number and grain number were unaffected as they are normally determined by pre-anthesis factors. Percentage grain protein was significantly reduced by both aphid species. The pattern of grain weight reduction within the ear was consistent with known limitations on the distribution of flag leaf assimilates among the grains. The relative effects of the two aphid species apparently resulted from the degree of nutrient drain imposed at particular feeding sites and the reduction in the leaf area duration of the flag leaf.

The role of the perennial stinging nettle, Urtica dioica, as a reservoir of beneficial natural enemies

Abstract: SUMMARY A wide range of natural enemies, including predators, parasites and entomophagous fungi were observed to feed on the stinging nettle aphid, Microlophium carnosum, populations of which increased rapidly in late April and early May. Patches of stinging nettles thus served as an important alternate feeding site for some beneficial natural enemies before pest aphids appeared on cultivated plants. Anthocoridae, Miridae and Coccinellidae were the most abundant specific predators sampled on nettles; only the Coccinellidae appeared to disperse over a defined period to other habitats. The hymenopterous parasites Aphidius ervi and Ephedrus lacertosus parasitized up to 10% of M. carnosum populations in June: two species of the fungus Entomophthora occurred spasmodically. Cutting patches of nettles in May or June had the most striking effect on the species and numbers of Coccinellidae. Cutting in mid-June might increase the numbers and impact of natural enemies on nearby pest infestations.

Thermal constants for development of the pea aphid (homoptera: aphididae) and some of its parasites

Abstract: The relationship between the temperature and the speed of development is described for the Kamloops ‘biotype’ of the pea aphid, Acyrthosiphon pisum, and some of its associated hymenopterous parasites. The primary parasites are: Aphidius ervi ervi, A. ervi pulcher, A. smithi, and Praon pequodorum; and the secondary parasites are: Asaphes lucens and Dendrocerus niger. For each species the lower temperature threshold for development and the time-to-adult was determined under constant laboratory conditions using field-grown alfalfa as a host plant for the pea aphid and the first-generation offspring of field-collected aphids and parasites. The thermal constants enable the prediction of aphid and parasite population growth, as influenced by temperature, on a physiological time-scale.

Predation on aphids in California’s alfalfa fields

Abstract: Alfalfa fields in two climatically different regions were sampled for aphids and their natural enemies throughout 3 years (1957-1959). The fields were under an integrated control program and therefore received minimum amounts of insecticides. The four imported parasites of the spotted alfalfa aphid and the pea aphid were not yet important in the study area, so predators were mainly responsible for the high degree of naturally occurring biological control. By pooling the data of entire regions, it was possible to follow changes in populations of these mobile predators more accurately than is possible from surveys of single fields because short-distance migration resulting from harvesting practices as well as uneven distribution could be neglected. Coccinellids and hemerobiids, two oligophagous groups, were closely linked in a density-dependent fashion to the aphid populations. This is a good indication that these predators (especially the lady beetles) are able to control the aphids. The more polyphagous predators, the chrysopidae and Hemiptera, become important in the control of the aphids only when the dominant coccinellids are inactive because of diapause or when lack of aphids for reproduction prompts the beetles to leave the fields. When aphid development exceeds the lady beetles’ momentary capacity for increase, however, syrphids are able to take a large toll. Furthermore, several species having similar biologies were found to replace each other throughout the year. Finally, the phenologies of the species could be explained by their biologies (diapause, temperature thresholds, ovipostional behavior).

Age‐Specific Energetics of the Pea Aphid, Acrythosiphon pisum

Abstract: A laboratory study of energy flow in different-aged pea aphids was accom- plished by the balance sheet method. Growth, reproduction, molted exoskeletons, oxygen consumption, and honeydew production were monitored daily. Absolute amounts of energy expended on reproduction, growth, maintenance, and rejecta all varied with age of the aphid. Efficiencies of production and respiration also varied with the life history stage. Assimilation efficiency did not vary with age. Gross production efficiency (x = 49%) and assimilation efficiency (x = 83%) are higher in this insect than in most other insects reported. The rea- son for such high efficiency may be the unusually high amino acid content of pea phloem sap. Rates of exudation of amino acids and sugars from pea phloem through severed aphid stylets are greater than twice the total daily energy requirement of continuously feeding aphids. This would be true even for passively feeding aphids. Under the study conditions the daily ingestion of one average adult aphid is approximately 8% of the daily net primary production of a 0.15 g (dry wt) pea seedling.

The effect of parasitism by aphidius smithi (hymenoptera: aphidiidae) on reproduction and population growth of the pea aphid (homoptera: aphididae)

Abstract: Parasitism by Aphidius smithi reduced the fecundity and population growth of pea aphid, Acyrthosiphon pisum . Aphids that were parasitized during the first or second instar period died as fourth instars without producing offspring. Parasitized third or fourth instars usually reached maturity and produced a variable number of progeny. Parasitized adult aphids stopped producing nymphs approximately 7 to 8 days following attack by A . smithi . Equations are given for the relationship between the mean total fecundity, the intrinsic rate of increase, and the doubling time of apterous and alate viviparous pea aphid and the aphid age at the beginning of parasitism.

Function of the siphunculi in aphids with particular reference to the sycamore aphid, Drepanosiphum platanoides

Abstract: Sycamore aphids with occluded siphunculi survive, give birth to as many offspring and maintain their weight as well as aphids with normal siphunculi and it is therefore unlikely that siphunculi have an excretory function. Blocking the siphunculi of sycamore aphids does not affect the way they space out. Siphunculi are used in defence against predators most effectively when the aphid and predator are similar in size.The smell of siphuncular exudate causes aphids like Myzus persicae to scatter but in the sycamore aphid the smell has to be accompanied by the sight or vibration of a struggling aphid to induce an alarm response. Prodding the abdomen and pinching the legs of a sycamore aphid induces it to produce siphuncular exudate.

Dispersal of the Grain Aphid Macrosiphum miscanthi from Australia to New Zealand

Abstract: Trans-oceanic dispersal of alate aphids (Hornoptera: Aphididae) \\.as first noted by Elton (1925), who found live aphids on the snows of Spitzbergen and suggested they had come from Kola Peninsula. northern U.S.S.R., a distance of 1300 km. Insects have been trapped on ships at sea, and in one such study off the coast of Argentina, Holzapfel. Tsuda and Harrell (1970) t~apped 2 aphids 1100 km from land, and one at 1500 km. In the Australia-New Zealand region the presence of certain aphid species on Macquarie (Eastop, 1962) and Campbell Islands (Cottier, 196-1) suggests dispersal of alatae from Australia or New Zealand. The grain aphid Macros~pl~um miscantlzi Takahashi has been present in Australia for many years (Eastop, 1966). In New Zealand it had been found on native grasses (Cottier, 1953), but not on ccreals. \ preliminary account of the development on this aphid to pest proportions on cereals is given by Lowe, who, in 1966, recorded the aphid on cereals and grasses in the North Island and in the northern part of the South Island, and in 1967 in Canterbury (Lowe, 1969).

The induction of leaf‐roll galls by the apple aphids Dysaphis devecta and D. plantaginea

Abstract: SUMMARY Dysaphis devecta causes the leaves of its host plant to roll laterally whereas D. plantaginea causes them to roll longitudinally. Both species of aphid are phloem feeders. D. devecta prefers to feed on the smaller veins in the lamina whereas D.plantaginea chooses the midrib. However, groups of D. devecta or D. plantaginea confined to the stem of an apple seedling induced young leaves several centimetres away to develop leaf rolls characteristic of each species. A single larva of D. devecta or D. plantaginea can induce a leaf-roll or a stem-bend on an apple seedling within 24 h. It is suggested that characteristic abnormalities in leaves attacked by D. devecta and D. plantaginea are caused by specific substances in the saliva of each aphid.

Reflective Mulches and Foliar Sprays for Suppression of Aphid-borne Viruses in Lettuce

Abstract: Field tests indicated that reflective mulches repelled alate aphids and reduced incidence of cucumber mosaic virus (CMV) in late-planted lettuce but did not adequately suppress wingless aphids. Acephate, pirimicarb, demeton, and to a lesser extent, parathion, controlled apterous aphids but did not significantly reduce virus transmission. Oil sprays (2.5%) did not reduce CMV incidence or suppress aphid populations. Yellow pan water traps showed that peak aphid flights occurred in August and Myzus persicae (Sulzer) was the predominating vector on the lettuce. CMV and trace amounts of broad bean wilt virus and lettuce mosaic virus were detected in infected lettuce by using either differential symptoms produced on the host range indicator, visualization of virus particles in an electron microscope, or serology.

The Toxic Effects of Fatty Acids and Their Salts on the Balsam Woolly Aphid, Adelgespiceae (Ratz.)

Abstract: Fatty acids and their potassium soaps were screened for their toxicity to different life stages and eggs of the balsam woolly aphid (Adelgespiceae (Ratz.)). The most effective fatty acids for causi...

The distribution of an intertidal aphid, Pemphigus trehernei foster, on marine saltmarshes.

Abstract: The intertidal aphid, Pemphigus trehernei, is restricted to aster plants (Aster tripolium) growing near the edges of creeks and salt pans in low areas on tidal saltmarshes Aphid populations in mid-marsh areas do not show an equivalent edge effect In low-marshes the edge soil generally has more surface cracks and cavities which can accommodate aphids and a higher % air space than soil from regions away from edges Adults and 1st instars can penetrate edge soil more readily than non-edge soil Aphid abundance is positively correlated with % air space in low-marsh regions Aphid populations established on potted asters were destroyed or reduced to very low levels when transferred to non-edge regions of low-marsh areas It is suggested that aphid distribution is primarily limited by soil conditions, especially the extent of soil drainage

The Effect on Selected Entomophagous Insects of Insecticides Applied for Pea Aphid Control in Alfalfa

Abstract: Four insecticides were equally effective in controlling Acythrosiphon pisum (Harris) but differed significantly in their impact on selected entomophagous insects. Pirimicarb (2-Dimethylamino-5, 6-dimethylprimidin-4-yl dimethylcarbamate) was generally the least disruptive to populations of Hippodamia convergens Guerin-Meneville, Nabis spp. and Orius spp. and methomyl and Vydate® (5-methyl 1-(dimethlcarbomoyl)-N-[methylcarbamoyl) oxy[ thioformimidate) were the most disruptive. Chrysopa spp. were relatively tolerant to all the materials tested.

Natural enemies of Toxoptera aurantii (Boy.) (Homoptera: Aphididae) on cocoa in Ghana

Abstract: Natural enemies of the black citrus aphid, Toxoptera aurantii (Boy.), on cocoa in Ghana are identified. Biology of some of the natural enemies is followed. Behaviour of the coccinellid and syrphid predators is studied in detail. Effectiveness of the predators in reducing the aphid populations is discussed.

Evaluation of Field Introductions of Two Insect Parasites (Hymenoptera: Braconidae) for Controlling Potato-infesting Aphids

Abstract: Two hymenopteran parasites, Diaretiella rapae (M'Intosh) and an as yet undescribed species of Praon that were reared in an insectary on green peach aphids, Myzus persicae (Sulzer), infesting Chinese cabbage, were mass released as late-stage pupae (in mummified aphids) among growing, aphid-infested potato plants. From the number of parasitized aphids (from which parasites had not yet emerged) found subsequently on potato plants sampled weekly after the introductions, neither species of parasite exerted a measurable influence on aphid populations in large field cages, in small field plots, or in small fields. Both species of wasps have been reared from naturally parasitized potato-infesting aphids in northeastern Maine, both in the field and in the insectary, over a period of many years. In this experiment, the insectary-reared parasites apparently emerged satisfactorily as adults from introduced, parasitized aphids, but they did not search out and oviposit in aphids on nearby potato plants. In planning future experiments of this nature, it seems evident that much more information will be needed on the behavior of the adult parasites and their reaction to various meteorological factors in the field.

Aphid-aphidophage community in Alfalfa cultures (Medicago sativa L.) in Poland. Pt. 1, Structure and phenology of the community

Abstract: Aphid-aphidophage community was studied in four regions of Poland. The sweep -net technique and catch per unit time provide a representative picture of the species composi­ tion if a series of 15-25 samples is used. In addition to Асуrthosiphon pisum ( H a r r i s ) , five groups of consumers are included to the community. Within two food chains, oligophagous predators and parasites, 126 species were recorded. A new concept of the aphid-aphidophage community structure has been developed. Among the dominant species there were 6 Coccinellidae, 7 Syrphidae and 3 Ghrysopidae. On each site the community is enriched in local, accessory species. Among the parasites a high stability of occurrence was observed for the ApMdiidae. Charipidae and Geraphronidae. The species composition of the Aphelinidae is not stable. The number dynamics of aphids has two peaks : in the spring-summer period and in the autumn, The appearance of aphidophages is significantly correlated with the first peak. ,, 3

A modified technique for rearing of the pea aphid on artificial diets.

Abstract: In various studies aphids have been reared on chemically defined nutrient solutions. Mittler & Dadd (1962) developed a now widely used technique by which an appropriate amount of diet is enclosed between two stretched Parafilm "M' | membranes which form a sachet. The sachet is stretched over the opening of a short section of a glass or plastic cylinder that serves as a feeding chamber. By frequently replacing the sachets with new ones (usually at intervals of 2 or 3 days) one ensures that oxidation of, and chemical interactions between, dietary components do not adversely affect aphid feeding and nutrition. While aphid performance may improve with such frequent changes, the manipulations necessary for transferring the aphids to a new sachet can result in some insects being injured (Mittler, 1972). Perhaps more important, handling can cause restlessness in some aphid species. Harrewijn (1973), for example, has shown that an increase in aphid activity may bias the results of studies on the effect(s) of nutritional factors on wing determination in Myzus persicae. In an attempt to reduce aphid handling as much as possible, we have modified Mittler & Dadd's sachet technique as follows (Fig. 1): (1) A Parafilm membrane (bm) is stretched across the upper opening of the aphid rearing chamber (c). (2) A second membrane (lm), which has been surface-sterilized with UV, is stretched over the first one. (3) A variable amount of sterile diet (d) is then placed onto the second membrane and sealed in with a third, surface-sterilized membrane (um) under aseptic conditions. (4) To renew the diet, it is only necessary to peel the sachet formed by the two uppermost membranes gently off the base membrane which covers the feeding chamber; a new sachet is then prepared as described above. The procedure allows the medium to be renewed as often as desired without disturbing the aphids at the same time. The periodic removal of honeydew from the cage walls with a moist cotton swab is the only additional maintenance required. The technique has been used for over one year in our laboratory and has given satisfactory results in the rearing (for three successive generations) of a laboratory strain of pea aphid (Acyrthosiphon pisum) on a holidic diet. The procedure was also used with potato aphid