Showing papers on "Aphid published in 1982"

How aphids choose leaves: the roles of phenolics in host selection by a galling aphid'

Abstract: The aphid Pemphigus betae does not induce galls at random on leaves of its host plant, Populus angustifolia (narrowleaf cottonwood). Probability of stem mother success in forming a gall, body mass of stem mother and progeny, number of progeny, development rate of progeny to maturity, and numbers of embryos in mature progeny are all correlated positively with leaf size at maturity. Leaf size at maturity is predictable from leaf position in the shoot at bud burst (Whitham 1978, 1980). The major secondary compounds of the host plant are known phenol glycosides. Using the Folin- Denis assay for total phenol determination, a strong inverse correlation has been established between the concentration of total phenols and suitability of a tree, leaf, or leaf section for galling at the time of bud burst, when the colonizing stem mothers are at the peak of their activity. Expanding leaves within the same shoot have different phenol concentrations; the potentially largest leaves have lower phenol levels. Leaves containing one or more incipient galls have lower phenol levels than leaves without galls. Phenol concentrations in leaves are not uniform; the existence of phenol gradients in leaves is demonstrated. In a comparison between two neighboring trees that are differentially infested with colonizing aphids, the tree with the higher aphid numbers per leaf has lower phenol levels in its leaves. These same leaves were shown to possess different average phenol gradients, suggesting that phenol gradients play a role in microhabitat selection. These findings are consistent with the known biology and territorial behavior of the aphid and provide a chemical basis for continuing studies on aphid habitat selection and fitness.

Inter-relationship between quinolizidine alkaloid producing legumes and infesting insects : exploitation of the alkaloid-containing phloem sap of Cytisus scoparius by the broom aphid Aphis cytisorum

Abstract: Abstract Aphids (Aphis cytisorum) which infest broom plants (Cytisus scoparius) accumulate up to 500 μg alkaloid/g fr. wt. The alkaloids, which are similar to those of the plants, consist of 17-oxo-sparteine, sparteine, 12,13-dehydrosparteine, and lupanine. Infested plants contain > 50% less alkaloids than aphid-free plants. In Lupinus aphid resistance which is due to their high alkaloid content is more expressed: Whereas bitter varieties are free from aphids, only the sweet alkaloid-free plants are susceptible to aphid infestation. The accumulation of alkaloids in aphids indicates that the quinolizidine alkaloids are translocated via the phloem in legume plants. This assumption is supported by direct evidence: analysis of phloem sap from Lupinus contains up to 5 mg alkaloid whereas xylem sap is virtually free of alkaloids. The interrelationship between quinolizidine alkaloids and hervivores is discussed.

Control of whitefly, Trialeurodes vaporariorum and cotton aphid, Aphis gossypii in glasshouses by two isolates of the fungus, Verticillium lecanii.

Abstract: SUMMARY The abilities of two isoiates of the entomopathogenic fungus, Verticillium lecanii (one isolated from whitefly and one from aphids), to control both aphids and whitefly on glasshouse cucumbers was investigated. Control of homologous hosts was better than that of heterologous hosts. A single spray of a commercial substrate-containing formulation of the ‘whitefly’ isolate controlled established whitefly populations satisfactorily on sprayed foliage and also when the whitefly moved up to younger untreated foliage. In addition, because the substrate permitted growth and sporulation of the fungus on leaf surfaces, whitefly populations introduced after a V. lecanii application were also controlled. Control of whitefly by the ‘aphid’ isolate alone was unsatisfactory although control could be obtained in conjunction with the hymenopterous parasite Encarsia formosa. Control of Aphis gossypii by the ‘aphid’ isolate was obtained by spraying a commercial formulation containing a substrate but not by spraying pure spore suspensions. The ‘whitefly’ isolate did not control aphids satisfactorily. The difference between the two isolates in pathogenicity for aphids and whitefly was supported by laboratory infectivity experiments.

Resistance of lettuce (Lactuca) to the leaf aphid Nasonovia ribis nigri. 1. Transfer of resistance from L. virosa to L. sativa by interspecific crosses

Abstract: Interspecific crosses were carried out between the three Lactuca species L. virosa, L. serriola and L. sativa to transfer resistance to the leaf aphid Nasonovia ribis nigri from L. virosa to the cultivated lettuce. L. sativa, L. serriola was used as an intermediate parent between the other two species. Many irregularities were observed in the interspecific hybrids, ranging from premature dying of F1 plants resulting from a kind of bastard necrosis till complete male and female sterility and deviating microsporogenesis. Using in vitro culture and after several backcrosses male and female fertile plants were obtained with a L. sativa habit and with resistance to the leaf aphid.

Host-symbiont interactions in the protein synthesis in the pea aphid

Abstract: Abstract (1) When the intracellular symbionts from the pea aphid were incubated with [ 35 S]-methionine, most of the proteins labelled differed from those detected by staining. The protein synthesis in vitro was completely inhibited by rifampicin and chloramphenicol but not at all by either of actinomycin D, α-amanitin and cycloheximide. (2) Protein syntheses in the whole insect and in the symbiont in vivo were studied by injecting [ 35 S]-methionine and antibiotics into the insect. The most heavily-labelled protein in the symbiont in vivo was a 43 kilodalton protein, which is probably actin. (3) The effect of antibiotics suggests two kinds of interaction occur between the host and symbiont wit hrespect to protein synthesis. The 43 kilodalton protein was coded by the host genome, synthesized in the eukaryotic machinery and transferred to the symbiont rapidly and selectively. The 63 kilodalton protein was also coded by the host genome but seemed to be synthesized in the prokaryotic machinery of the symbiont.

Glandular pubescence, glycoalkaloid composition, and resistance to the green peach aphid, potato leafhopper, and potato fleabeetle inSolanum berthaultii

Abstract: Fifteen accessions ofSolarium berthaultii Hawkes andS. berthaultii xS. tarijense Hawkes were assessed for resistance to field infestations of the green peach aphid,Myzus persicae (Sulzer), potato leafhopper,Empoasca fabae (Harris), and potato fleabeetle,Epitrix cucumeris (Harris). Accessions bearing both Type A and Type B glandular trichomes were much more resistant to the green peach aphid and potato leafhopper than accessions bearing Type A hairs alone. All accessions had significantly smaller populations of these 3 pests than S.tuberosum cultivars. Total glycoalkaloid (TGA) content of foliage and tubers was not correlated with insect populations. Foliar TGA levels of field-grown plants varied among accessions, ranging from < 2–240 mg/100 g fresh wt. Solasonine and solamargine were the major foliar glycoalkaloids while solamarines predominated in tubers.

Aphid genotypes, plant phenotypes, and genetic diversity: a demographic analysis of experimental data.

Abstract: It is well known that many populations possess substantial amounts of electrophoretically detectable genetic variation. There is accumulating evidence that this variation has adaptive significance, and that environmental heterogeneity is an important factor in the maintenance of this variation (see Hedrick et al., 1976, for a review). In the case of clonal organisms, genetic diversity can be maintained in a population if no clone is relatively most fit in all environments. This argument may be applied to a variety of ecological relationships, including that of an aphid to its host plant. Specifically, we hypothesize that there is an interaction between aphid genotypes and host plant phenotypes such that no aphid clone is relatively most fit on all host phenotypes. The plausibility of this hypothesis is supported by three recent studies of natural populations of phytophagous insects (Edmunds and Alstad, 1978; Mitter et al., 1979; Moran, 1981), and by the vast literature on crop plants and their arthropod pests (e.g., Cartier, 1963; Hatchett and Gallun, 1970; Lowe, 1974; Gould, 1979). In this paper we report on an experiment designed to test the hypothesis of interaction between aphid genotypes and host plant phenotypes, using a new methodology for the analysis of life history data (Lenski and Service, 1982).

Secondary host preferences and reproductive activity of the bird cherry‐oat aphid, Rhopalosiphum padi

Abstract: SUMMARY Of 15 species of grass, including cereals, alate exules and emigrants of Rhopalosiphum padi preferred to colonise Lolium perenne. Emigrants colonised cereals twice as readily as alate exules. Apterous exules also preferred L. perenne to cereals. Although small when reared on L. perenne, R. padi was more fecund per unit weight than on any of the other grasses tested. On the later growth stages of Dactylis glomerata and L. perenne, R. padi developed faster and were more fecund than on Phleum pratense at the same growth stages. At low temperatures R. padi were more fecund on P. pratense than on L. perenne and D. glomerata and vice versa at high temperatures. The secondary host preferences and reproductive activity of R. padi are discussed in relation to possible suitable hosts for viviparous overwintering and the pest status of this aphid in Britain.

The influence of carpenter ant ( camponotus modoc ) (hymenoptera: formicidae) attendance on the development and survival of aphids ( cinara spp.) (homoptera: aphididae) in a giant sequoia forest

Abstract: Camponotus modoc was associated with numerous species of Homoptera in Giant Forest, Sequoia — Kings Canyon National Park, California. Ant-exclusion experiments and field observations indicated that survival of the abundant Cinara occidentalis Davidson on white fir depends on attendance by C. modoc . More of the predators, Neomysia oblonguttata (Mulsant), Deraeocoris brevis Uhler, Passaloecus cuspidatus F. Smith, Pityophyphantes sp., were found on ant-unattended than on attended aphid colonies. As aphid populations decreased, ant attendance per aphid and number of predators/aphid increased. Attended aphid colonies were more likely to survive to produce oviparae and a lower proportion of alates.

Studies on Alfalfa Mosaic Virus and Alfalfa Aphids

Abstract: Alfalfa mosaic virus (AMV), the only sap-transmissible virus detected in a limited survey of lucerne crops in New South Wales and the Australian Capital Territory, is more common and widespread now than 10 years ago. Twenty-four of 35 lucerne crops and test plots we sampled were infected; from 25 % to over 55 % of plants were infected in plots and crops at Ginninderra, A.C.T. Seven of 10 commercial lucerne seed lots (eight of them imported directly from the U.S.A.) contained seedborne AMV, which infected from 0.4 to 1.9% of seedlings. The three lucerne aphids, the bluegreen aphid (Acyrthosiphon kondoi), pea aphid (A. pisum) and the spotted alfalfa aphid (Therioaphis trifolii f. maculata), all transmitted AMV in the non-persistent manner. Feeding-preference tests indicate that spotted alfalfa aphids prefer to feed on AMV-infected Siriver lucerne than on healthy Siriver, but they do not discriminate between healthy and AMV-infected Hunter River lucerne. The implications of these results are discussed.

Assessment of methods for estimating the numbers of aphids (Hemiptera: Aphididae) in Cereals

Abstract: Visual counting was found to be the most accurate method of estimating cereal aphid numbers in field studies in England. Vacuum sampling decreased in efficiency as aphid density increased, but could be a useful alternative to visual counts at very low aphid densities when the latter became too time-consuming. Cutting tillers for later washing in the laboratory was less efficient than visual counting as aphids, especially Metopolophium dirhodum (Wlk.), fell off the plants during sampling, but this method was useful in determining the proportion of different morphs of Sitobion avenae (F.) present at very high densities.

Green Peach Aphid Feeding Damage to Potato in Various Plant Growth Stages

Abstract: The effects of Myzus persicae (Sulzer) infestations on potato foliage and tuber production were studied at 3 consecutive degree-day (DD) intervals (ca. 20 days each). Plants were harvested immediately after an infestation period, or after infestation they were maintained aphid free until the end of the experiment. The interval of aphid-free growth after infestation was used to determine whether the plant could resume normal growth and how infestation affected final yield. Infested plants exhibited the following reductions in dry weight: first period (DD = 519), no tubers for comparison; second period (DD = 745), 54% reduction; and third period (DD = 963), 17% reduction. Plants maintained aphid free after first-period infestation showed a 35% reduction in tuber dry weight at final harvest. Aphid feeding during any period decreased the moisture content of infested leaves. Plants under the stress of early-season infestation allocated more resources for leaf growth, but stem growth was severely retarded.

Performance of the Cabbage Aphid, Brevicoryne Brassicae (L.), On Water-Stressed Rape Plants, in Relation to Changes in Their Chemical Composition.

Abstract: Lack of water increases the total amino acid content of the leaves and phloem sap of rape plants. The concentration of proline, in particular, increases and is strongly negatively correlated with relative water content. Lack of water also causes a decrease in total carbohydrates, but appears to have no significant effect on total phenolics. Water stress increases the rate of development of aphids born on the plant. but as stress becomes pronounced, the insects become restless. No consistent effect on fecundity was observed, and survival was very high, regardless of water-regime, up to the time the plants became so wilted as to be rejected by the insects.

Laboratory assessments of resistance to the aphids Sitobion avenae and Metopolophium dirhodum in three Triticum species and two modern wheat cultivars.

Abstract: SUMMARY Three ancient varieties of wheat and two spring-sown modern varieties were screened in the laboratory to assess their resistance to the cereal aphids Sitobion avenae and Metopolophium dirhodum. Resistance was measured in terms of non-preference and antibiosis on plants at three growth stages. The ancient variety Einkorn was the most resistant in terms of both non-preference and antibiosis to both species of aphids at all growth stages examined. The ancient variety Emmer and the modern Sicco exhibited some resistant properties, whereas the ancient Spelt and modern Timmo were relatively susceptible to aphid attack.

Green peach aphid resistance by glandular trichomes in Solanum tuberosum x S. berthaultii hybrids

Abstract: Three interspecific F3 hybrid clones ofSolarium tuberosum L. x 5.berthaultii Hawkes bearing both Type A and Type B glandular trichomes were assessed for resistance to the green peach aphid,Myzus persicae (Sulzer). In glasshouse trials, aphid mortality and population development on hybrid clones were similar to those on the aphid-resistant parent,S. berthaultii. Trichome exudate of the hybrid, B227-63, was as effective in aphid immobilization as that ofS. berthaultii. Field populations of the green peach aphid on hybrids were intermediate between those onS. berthaultii and susceptibleS. tuberosum cultivars.

Using Temperature-Mediated Functional Response Models to Predict the Impact of Coleomegilla maculata (DeGeer) Adults and 3rd-Instar Larvae on Green Peach Aphids

Abstract: The effects of temperature and prey density on Coleomegilla maculata (DeGeer) feeding on Myzus persicae (Sulzer) were determined to quantify their impact on the C. maculata-M. persicae interaction. Seven temperatures ranging from 15.6 to 32.2° C were employed in the study. Nine prey densities per temperature and two predator and prey age classes per prey density were also used. An enzyme kinetic equation was used to describe the change with temperature in the green peach aphid intrinsic rates of increase and the C. maculata larval and adult search rates. The larval and adult handling rates were determined to be linearly related to temperature over the range studied. The short-term impact of C. maculata adults and 3rd-instar larvae on green peach aphids was simulated by substituting these equations into two aphid growth rate models. Both models predicted that C. maculata 3rd-instar larvae and adults would be most effective in reducing the aphid population in temperatures above 29° C.

Fecundity and host utilization of the aphid parasite aphelinus semiflavus (hymenoptera: aphelinidae) at two host densities

Abstract: The longevity, fecundity, and oviposition rates of Aphelinus semiflavus Howard were determined at densities of 20 and 60 pea aphid hosts per day. Host density had no significant effect on parasite longevity and total fecundity, but it did influence the mean daily oviposition rate (16.5 and 19.5 aphids/day at density 20 and 60, respectively) and the overall proportion of aphids parasitized (82.3% and 32.5%, respectively) during the period of maximum egg laying. The implications of a shift in the fecundity schedule to an earlier reproductive age are discussed.

Aphid alarm pheromone derivatives affecting settling and transmission of plant viruses

Abstract: 1,4-Cycloaddition reactions between (E)-β-farnesene (the aphid alarm pheromone) and dienophiles, such as SO2 and RO·CO·C ≡ CCO·OR, gave products more stable and less volatile than the parent compound. In laboratory experiments, the numbers ofMyzus persicae (Sulz.) settling and nymphs deposited on plants were decreased by some of the reaction products. Acquisition, and thereby transmission, of the semipersistent beet yellows virus and the nonpersistent potato virus Y, was decreased.

Linden Aphid Parasite Establishment

Abstract: The linden aphid, Eucallipterus tiliae L. (Homoptera: Callaphididae), is a pest on linden trees, Tilia spp., which are common as urban shade trees throughout North America. The aphidiid Trioxys curvicaudus Mackauer (Hymenoptera: Aphidiidae), which is monophagous on E. tilia , was imported from Europe and released in Berkeley, Calif., where it became established. Subsequent observations showed that the parasite had effectively reduced linden aphid populations below an aesthetic injury level.

A kleptoparasitic moth, Nola innocua, attacking aphid galls

Abstract: Larvae of some moths bore into galls formed by other insects and feed on the tissue (e.g. Walsh, 1866; Takahashi, 1935; Mani, 1964). Although two gelechioid moths, Batrachedra mlicipo mo nella Clemens and B. striolata Zeller, were said to be found only in galls formed by Ponfania sawflies (Caltagirone, 1964; Hodges, 1966). there are no definite records, so far, of obligatory cecidophagous moths (M. S. Mani, personal communication). The aphid, Nipponaphis distyliicoia Monzen, forms figshaped green galls on the shoots of Distylium racemosum Siebold et Zuccarini, an evergreen broad-leaved tree, in Japan in May. The wall of the gall is juicy but tough and about 2mm thick. It was found that larvae of a nolid moth, Nola innocua Butler (classification according to Inoue, 1976), bore into galls and fed on the internal tissue, leaving only the outer skin; the colour of the inside wall of the gall then changes to black. A larva sometimes attacks two or more galls before completing its growth. Galls attacked by the moth can be easily distinguished by openings and faecal pellets remaining in the gall (Fig. la). The mature larva emerges from the gall, spins a rough cocoon on the surface of a twig near the gall and pupates. This species seems to pass through two to three generations on Nipponaphis galls during July and August, but