Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “aphids”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources
PubMed2005

Aphid clonal resistance to a parasitoid fails under heat stress.

Parasitoid virulence and host resistance are complex interactions depending on metabolic rate and cellular activity, which in aphids additionally implicate heritable secondary symbionts among the Enterobacteriaceae. As performance of the parasitoid, the aphid host and its symbionts may differentially respond to temperature, the success or failure of aphid parasitism is difficult to predict when temperature varies. We tested the hypothesis that resistance of the pea aphid Acyrthosiphon pisum to the parasitoid Aphidius ervi, which is linked to aphid secondary symbionts, may depend on temperature in several resistant and non-resistant aphid clonal lineages of different geographic origin and of known bacterial symbiosis, using experiments in controlled environments. Complete immunity to A. ervi at 20 degrees C in three different aphid clones whose symbiosis is characterized by the possession of Hamiltonella defensa reversed to high susceptibility at 25 degrees C and especially 30 degrees C, suggesting that the aphid's immune responses to the establishment and early development of the parasitoid is strongly reduced at moderately high temperatures. There was no evidence that a pea aphid control genotype that was susceptible to A. ervi at 20 degrees C could become more resistant as temperature increases, as has been suggested for insect fungal pathogens. By contrast, our results suggest that aphid clonal resistance to A. ervi and related parasitoids is characteristic of cool temperature conditions, similar to various other fitness attributes of aphids. Based on evidence that H. defensa symbionts characterized all three A. ervi resistant pea aphid clones studied, but was absent in control aphids that remained susceptible at all temperatures, we suggest that secondary symbiosis plays a key role in the heat sensitivity of aphid clonal resistance. Our study may also indicate that aphid natural control of variably susceptible host populations by aphid parasitoids is more likely at moderate to high temperatures.

Animals↗
PubMed2000

Relative suitability of crested wheatgrass and other perennial grass hosts for the Russian wheat aphid (Homoptera: Aphididae).

The Russian wheat aphid, Diuraphis noxia (Mordvilko) (Homoptera: Aphididae), reproduces parthenogenetically in North America and must survive year-round on host plants, including in late summer when small grains are not in cultivation. During this time, cool-season perennial wheatgrasses (Poaceae: Triticeae) contribute substantially to aphid survival, crested wheatgrass (Agropyron spp.) particularly. In greenhouse studies, the number of aphids per plant was measured after four infestation periods on unvernalized and vernalized wheatgrasses. Before placement on these test plant species, aphids were reared either on winter wheat or on the grass host species on which aphid progeny were counted. On vernalized plants, aphids reared on wheat resulted in more aphids per test plant than when the aphids were reared on wheatgrasses, but on unvernalized plants the number of aphids per test plant did not differ significantly regardless of rearing host. Aphids on crested wheatgrass were similar in number to the other grasses when plants were unvernalized. However, when plants were vernalized, crested wheatgrass supported significantly more aphids than some of the other hosts. Aphid numbers increased on all test species as infestation period lengthened, and plant growth was largely unaffected by aphid feeding. These results suggest if sufficient moisture is available during summer when small grains are not in cultivation, all host species observed are capable of sustaining aphids. Crested wheatgrass is an abundant and important host of the Russian wheat aphid in its northern range of the western United States, but other less prevalent wheatgrasses also may contribute to aphid survival during late summer when small grains are not in cultivation.

Animals↗
PubMed2006

Sources of variation in the interaction between three cereal aphids (Hemiptera: Aphididae) and wheat (Poaceae).

The relative contributions of host plant, herbivore species and clone to variation in the interaction between cereal aphids and wheat were investigated using five clones each of three species, Rhopalosiphum padi (Linnaeus), Sitobion avenae (Fabricius) and Schizaphis graminum (Rondani), on seedlings of two cultivars of Triticum aestivum L. and one cultivar of Triticum durum Desf. More individuals and biomass of R. padi than of the other two species were produced on seedlings. The three wheat cultivars lost similar amounts of biomass as a result of infestation by aphids, with the amount lost depending on aphid species: S. avenae caused the lowest loss in biomass. Variation in aphid biomass production was due mostly to differences among aphid species (70%), less to the interaction between wheat type and aphid species (7%), and least to aphid clone (1%). The specific impact of the aphids on the plants ranged from 1.7 to 3.7 mg of plant biomass lost per mg of aphid biomass gained, being lowest for R. padi and highest for S. graminum. Variation in plant biomass lost to herbivory was due mostly to unknown sources of error (95%), probably phenotypic differences among individual seedlings, with 3% due to aphid species and none attributable to aphid clone. For these aphid-plant interactions, differences among aphid clones within species contributed little to variation in aphid and plant productivity; therefore, a small sample of clones was adequate for quantifying the interactions. Furthermore, one clone of each species maintained in the laboratory for about 200 parthenogenetic generations was indistinguishable from clones collected recently from the field.

Analysis of Variance↗
PubMed1997

Honeydew sugars and osmoregulation in the pea aphid Acyrthosiphon pisum

Pea aphids, Acyrthosiphon pisum, containing their symbiotic bacteria (untreated aphids) and experimentally deprived of their bacteria by treatment with the antibiotic rifampicin (antibiotic-treated aphids) were reared on the plant Vicia faba. The sugars in the honeydew produced by untreated aphids comprised predominantly the monosaccharides glucose and fructose, while the honeydew of antibiotic-treated aphids contained considerable amounts of oligosaccharides of up to 16 hexose units. The honeydew and haemolymph of the aphids were iso-osmotic, and their osmotic pressure was significantly lower in untreated aphids (0.91&shy;0.95 MPa) than in antibiotic-treated aphids (1.01&shy;1.05 MPa) (P<0.05). For insects reared on chemically defined diets containing 0.15&shy;1.0 mol l-1 sucrose (osmotic pressure 1.1&shy;4.0 MPa), the osmotic pressure of the aphid haemolymph did not vary with dietary osmotic pressure, but was regulated to approximately 1.0 MPa in untreated and 1.3 MPa in antibiotic-treated aphids. The sugars in the aphid honeydew varied with dietary sucrose concentration; with monosaccharides dominant at low concentrations and oligosaccharides dominant at high concentrations of dietary sucrose. The lowest dietary sucrose concentration at which honeydew oligosaccharides were detected was 0.2 mol l-1 for the antibiotic-treated aphids and 0.3 mol l-1 for untreated aphids. These data indicate that the aphid, and not its associated microbiota, mediates the synthesis of oligosaccharides when the osmotic pressure of the ingesta is high.

Journal Article↗
PubMed2004

Estimation of the number of aphids carrying Citrus tristeza virus that visit adult citrus trees.

Aphid species were counted on citrus trees in orchards in Valencia, Spain, in the spring and autumn of 1997, 1998 and 1999. Moericke yellow water traps, the 'sticky shoot' method and counts of established colonies were used in extensive surveys in which 29,502 aphids were recorded and identified. Aphis spiraecola and Aphis gossypii were the most abundant aphid species. The numbers of aphid species landing on mature trees of grapefruit, sweet orange, lemon and clementine and satsuma mandarins, were estimated by counting the numbers of young shoots/tree and aphids trapped on sticky shoots. The proportions of the different aphid species captured were: A. gossypii (53%), A. spiraecola (32%), Toxoptera aurantii (11%), Myzus persicae (1%), Aphis craccivora (1%) and other species (2%). Clementine was the most visited species with 266,700 aphids landing/tree in spring 2000, followed by lemon (147,000), sweet orange (129,150), grapefruit (103,200), and satsuma (92,400). The numbers and relative percentages of aphids carrying Citrus tristeza virus (CTV) were assessed by nested RT-PCR in single closed tubes and analysed by extraction of RNA-CTV targets from trapped aphids. An average of 37,190 CTV-carrying aphids visited each tree in spring 2000 (29 per shoot). The percentage detection of viral RNA in the aphid species that landed were 27% for A. gossypii, 23% for A. spiraecola and 19% for T. aurantii. This high incidence of aphids carrying CTV is consistent with the high prevalence and rapid spread of CTV in sweet orange, clementine, and satsuma mandarins in recent years in the region. The infection rate was proportional to the number of aphids landing/tree.

Animals↗
PubMed2004

The role of honeydew in host searching of aphid hyperparasitoids.

Foraging in many insect parasitoids is mediated by chemicals associated with hosts. For example, honeydew, the feces of feeding aphids, induces and/or prolongs searching behavior of aphid parasitoids. In the laboratory, we tested if aphid hyperparasitoids, which belong to a higher trophic level, also rely on aphid honeydew to locate their hosts. We used the potato aphid. Macrosiphum euphorbiae, the primary parasitoid, Aphidius nigripes, and four hyperparasitoids, Asaphes suspensus, Dendrocerus carpenteri. Alloxysta victrix, and Syrphophagus aphidivorus that possess different biological attributes and host ranges. We determined if foraging hyperparasitoid females could discriminate between (i) honeydew from a host and a non-aphid host (the potato aphid and the soft brown scale, Coccus hesperidum), and (ii) honeydew from healthy aphids and those parasitized by A. nigripes. Females of A. suspensus did not react to any of the honeydew treatments. While the presence of non-aphid honeydew did not modify the behavior of A. victrix, D. carpenteri, and S. aphidivorus females, they exhibited an increase in searching time and path length but not walking speed when in the presence of honeydew from aphids. However, there were no changes in host searching behaviors, such as antennation or ovipositor probing that have been reported for primary aphid parasitoids. There was no difference in the response of hyperparasitoid females to honeydew from healthy and parasitized aphids. These results indicate that hyperparasitoids may use aphid honeydew, a conspicuous cue from the second trophic level, as an infochemical to locate their hosts.

Animals↗
PubMed2004

Prey selection by linyphiid spiders: molecular tracking of the effects of alternative prey on rates of aphid consumption in the field.

A molecular approach, using aphid-specific monoclonal antibodies, was used to test the hypothesis that alternative prey can affect predation on aphids by linyphiid spiders. These spiders locate their webs in cereal crops within microsites where prey density is high. Previous work demonstrated that of two subfamilies of Linyphiidae, one, the Linyphiinae, is web-dependent and makes its webs at sites where they were more likely to intercept flying insects plus those (principally aphids) falling from the crop above. The other, the Erigoninae, is less web-dependent, making its webs at ground level at sites with higher densities of ground-living detritivores, especially Collembola. The guts of the spiders were analysed to detect aphid proteins using enzyme-linked immunosorbent assay (ELISA). Female spiders were consuming more aphid than males of both subfamilies and female Linyphiinae were, as predicted, eating more aphid than female Erigoninae. Rates of predation on aphids by Linyphiinae were related to aphid density and were not affected by the availability of alternative prey. However, predation by the Erigoninae on aphids was significantly affected by Collembola density. Itinerant Linyphiinae, caught away from their webs, contained the same concentration of aphid in their guts as web-owners. However, nonweb-owning Erigoninae, living away from Collembola aggregations at web-sites, contained significantly higher concentrations of aphid. For both subfamilies there was evidence of a disproportionate increase in predation on aphids once Collembola populations had declined. It was concluded that nonaphid prey, by helping to maintain spiders in the field, can significantly affect predation on aphids.

Animals↗
PubMed2003

Diversity of bacteria associated with natural aphid populations.

The bacterial communities of aphids were investigated by terminal restriction fragment length polymorphism and denaturing gradient gel electrophoresis analysis of 16S rRNA gene fragments generated by PCR with general eubacterial primers. By both methods, the gamma-proteobacterium Buchnera was detected in laboratory cultures of six parthenogenetic lines of the pea aphid Acyrthosiphon pisum and one line of the black bean aphid Aphis fabae, and one or more of four previously described bacterial taxa were also detected in all aphid lines except one of A. pisum. These latter bacteria, collectively known as secondary symbionts or accessory bacteria, comprised three taxa of gamma-proteobacteria (R-type [PASS], T-type [PABS], and U-type [PAUS]) and a rickettsia (S-type [PAR]). Complementary analysis of aphids from natural populations of four aphid species (A. pisum [n = 74], Amphorophora rubi [n = 109], Aphis sarothamni [n = 42], and Microlophium carnosum [n = 101]) from a single geographical location revealed Buchnera and up to three taxa of accessory bacteria, but no other bacterial taxa, in each aphid. The prevalence of accessory bacterial taxa varied significantly among aphid species but not with the sampling month (between June and August 2000). These results indicate that the accessory bacterial taxa are distributed across multiple aphid species, although with variable prevalence, and that laboratory culture does not generally result in a shift in the bacterial community in aphids. Both the transmission patterns of the accessory bacteria between individual aphids and their impact on aphid fitness are suggested to influence the prevalence of accessory bacterial taxa in natural aphid populations.

Animals↗
PubMed1998

Implications of predator foraging on aphid pathogen dynamics.

The foraging behavior of starved and nonstarved second and fourth instar Coccinella septempunctata larvae on dead Acyrthosiphon pisum aphids, either infected with the entomopathogenic fungus Erynia neoaphidis (sporulating) or uninfected, was examined. Larvae searched for longer and fed less when presented with infected rather than uninfected A. pisum. Although no sporulating infected aphids were completely consumed, both adult and larval ladybirds can still be considered as intraguild predators. In a further study, fourth instar larvae fed on dying infected, dead infected (not sporulating), and dead uninfected aphids for similar periods of time but again the infected aphids were seldom entirely consumed. Live uninfected aphids were fed upon for significantly longer than any other prey. Infected aphids which were damaged at an early stage of infection (0, 1, or 2 days after inoculation) did not sporulate, whereas damaged moribund aphids (3 days after inoculation) did subsequently sporulate. Damaged sporulating cadavers continued to sporulate. However, damage to moribund and sporulating infected aphids, both mechanical or due to C. septempunctata feeding, reduced the number of conidia subsequently produced. Larval feeding caused the most significant reduction. Under laboratory conditions, C. septempunctata foraging on infected aphids did, therefore, reduce the pathogen density. However, conidia produced from a damaged cadaver resulted in levels of transmission to healthy aphids comparable to that resulting from an intact cadaver. Furthermore, the presence of a foraging adult ladybird resulted in a significant increase in transmission of the fungus to healthy aphids. Preliminary studies to assess the potential of other aphid natural enemies as intraguild predators illustrated that adults of the generalist carabid, Pterostichus madidus, entirely consumed sporulating cadavers. Third instar lacewing, Chrysoperla carnea, and hoverfly, Episyrphus balteatus, larvae never fed on sporulating cadavers. The ecological implications of these results are discussed.

Animals↗
PubMed2006

Cytochrome c oxidase mRNA as an internal control for detection of Potato virus Y and Potato leafroll virus from single aphids by a co-amplification RT-PCR assay.

Using cytochrome c oxidase subunit 1 (COX1) mRNA as the internal control, a triplex reverse transcription-polymerase chain reaction (RT-PCR) for detection of Potato virus Y (PVY) and Potato leafroll virus (PLRV) with co-amplification of COX1 from single specimens of various aphid species has been developed. Partial length cDNA of COX1 from green peach aphid, Myzus persicae (Sulzer), potato aphid, Macrosiphum euphorbiae (Thomas), buckthorn aphid, Aphis nasturtii (Kaltenbach), and pea aphid, Acyrthosiphom pisum (Harris), was cloned and sequenced. These sequences, together with existing COX1 sequences from other aphid species capable or suspected to be capable of transmitting PVY and/or PLRV, were analyzed. The sequence identity between any two aphid species ranged from 97 to 100% at the putative protein level, and 89 to 94% at the nucleic acid level. Two highly conserved COX1 nucleotide sequence stretches were selected to design universal primers Aph F and Aph R. This primer pair, together with two existing universal primer pairs (C1-J-2183 and C1-N-2329; Favret F and Favret R), were evaluated at the optimal annealing temperature using RNA from M. persicase, M. euphorbiae, and A. nasturtii. The Aph primer pair performed well in the monoplex RT-PCR but poorly in the triplex RT-PCR in the presence of the PVY- and PLRV-specific primers. On the other hand, the Favret and C1 primer pairs performed well in both monoplex and triplex RT-PCR formats using single aphids of M. persicase, M. euphorbiae and A. nasturtii, demonstrating their suitability to indicate the successfulness of RT-PCR assays for PVY and PLRV. Using the Favret, PVY and PLRV primer sets, single aphids of M. persicase, M. euphorbiae and A. nasturtii that had been exposed to PLRV-infected and/or PVY-infected potato plants were assessed for their acquisition of the viruses by the triplex RT-PCR assay. Although majority (175/180) of the aphid samples produced the COX1 fragment, five aphid samples failed to produce either the COX1- or the virus-specific band, indicating failed RT-PCR in these samples. This method offers a sensitive tool for detection of viruliferous aphids combined to an effective quality control measure.

Animals↗
PubMed2002

Behavioral and electrophysiological responses of natural enemies to synomones from tea shoots and kairomones from tea aphids, Toxoptera aurantii.

Olfactometer bioassays and electrophysiological studies showed that the lacewing, Chrysopa sinica, the aphid parasitoid, Aphidius sp., and the coccinellid, Coccinella septempunctata, all responded to volatiles from tea aphids, Toxoptera aurantii, to hexane or ether rinses of tea aphid cuticles, and to synomones released by aphid-damaged tea shoots, as well as to the tea shoot-aphid complex. Each natural enemy spent more time searching on a filter paper treated with tea aphid honeydew than on a blank control filter paper. The interaction between synomones from aphid-damaged shoots and kairomones from tea aphids enhanced the responses to the plant-host complex. There was a significant, logistic dose-response relationship between the number of natural enemies responding and the odor stimulus concentration. Volatile components from the plant-host complex, obtained by air entrainment, were identified by their mass spectra and retention times and confirmed by comparison with standard samples. These were (Z)-3-hexen-1-ol, benzaldehyde, (E)-2-hexenal, (Z)-3-hexenyl acetate, ocimene, linalool, geraniol, indole, and (E)-2-hexenoic acid. The main components in a hexane rinse from tea aphid cuticle were benzaldehyde, undecane, 2,5-hexanedione, 2,5-dihydrothiophene, linalool, 4-methyl-octane, and eicosane, whereas the main components from an ether rinse were (E)-2-hexenoic acid, heptadecane, pentadecane, eicosane, tetratetracontane, and nonadecane. Benzaldehyde elicited the strongest responses from natural enemies in theolfactometer and the largest electroantennogram (EAG) responses. While the amount of odor was small, Coccinella septempunctata was slightly more sensitive than Chrysopa sinica and Aphidius sp. An increase in doses of benzaldehyde, (E)-2-hexenal, and (Z)-3-hexenyl acetate caused the EAG responses of each natural enemy to decrease. When the doses of (Z)-3-hexen-1-ol, linalool, and geranoil increased, EAGs of Chrysopa sinica and Aphidius sp. increased, but EAGs of Coccinella septempunctata decreased. When the dose of indole increased, EAGs of Coccineila septempunctata decreased, but those of Aphidius sp. increased. This study demonstrates that tea shoot-aphid complexes emit volatile synomones, while the odors from tea aphids, aphidcuticle extracts, and tea aphid honeydew contain kairomones, to which the natulal enemies show a logistic dose-response.

Animals↗
PubMed2003

Facultative symbionts are associated with host plant specialization in pea aphid populations.

The pea aphid, Acyrthosiphon pisum, shows significant reproductive isolation and host plant specialization between populations on alfalfa and clover in New York. We examine whether specialization is seen in pea aphids in California, and whether fitness on alternative host plants is associated with the presence of bacterial symbionts. We measured the fitness of alfalfa- and clover-derived aphids on both types of plants and found no evidence for specialization when all aphid lineages were considered simultaneously. We then screened all aphids for the presence of four facultative bacterial symbionts: PAR, PASS, PABS and PAUS. Aphids with PAUS were host-plant specialized, having twice as many offspring as other aphids on clover, and dying on alfalfa. Other aphids showed no evidence of specialization. Additionally, aphids with PABS had 50% more offspring than aphids with PASS when on alfalfa. Thus, specialist and generalist aphid lineages coexist, and specialization is symbiont associated. Further work will resolve whether PAUS is directly responsible for this variation in fitness or whether PAUS is incidentally associated with host-plant specialized aphid lineages.

Adaptation, Physiological↗
PubMed1996

Loss of potyvirus transmissibility and helper-component activity correlate with non-retention of virions in aphid stylets.

The hypothesis that loss of aphid transmissibility of potyvirus mutants is due to non-retention of virions in the mouthparts was tested by feeding aphids through membranes on purified virions of aphid transmissible (AT or HAT) and non-aphid-transmissible (NAT) tobacco vein mottling virus (TVMV) or tobacco etch virus (TEV), in the presence of functional [potato virus Y (PVY) HC or TVMV HC] or non-functional (PVC HC) helper component (HC). TVMV virions were detected, by electron microscopic examination of immunogold-labelled thin sections, in the food canal or cibarium of 57% of 28 aphids fed on the transmissible combination of TVMV-AT and functional HC, while no virions were found in these structures in 25 aphids fed on the non-transmissible combinations: TVMV-NAT and PVY HC, or TVMV-AT and PVC HC. Autoradiography of intact stylets allowed the examination of much larger numbers of aphids, fed on 125I-labelled TEV; 48% of 523 aphids fed on the TEV-HAT and PVY HC combination retained label in the stylets: this correlated well with the percentage transmission in bioassays. In contrast, in non-transmissible combinations, label was found in the stylets of 0.77% of 389 aphids fed on TEV-NAT and PVY HC, and 1.35% of 223 aphids fed on TEV-HAT and PVC HC. No differences were found in the overall amount of label in the bodies of aphids fed on the transmissible and non-transmissible combinations. There was a strong tendency for virions to be retained in the distal third of the stylets; 56% of aphids positive for TVMV, and 82% of those positive for TEV, had label in this area. These data support the concept that virions retained within the stylets are those that are primarily involved in potyvirus transmission.

Amino Acid Sequence↗
PubMed2001

Plant washing as a pest management technique for control of aphids (Homoptera: Aphididae).

Changes in aphid presence following plant washings were evaluated on hibiscus plants, Hibiscus rosa-sinensis L., that supported natural aphid infestations--primarily melon aphid, Aphis gossypii Clover. Type of plant module (such as stems, tight buds, open flowers, and sepal caps) and percent of module's surface covered by aphids were recorded for each branch tip on every plant. Plant washing was done with tap water, applied for 30 s three times a week for 3 wk. Aphid presence was recorded each week. Aphid presence on plant structures immediately before and after a single 30-s wash treatment was also examined. In the 3-wk study, mean percent coverage of plant parts with aphids was significantly affected by wash treatment, plant module type, and their interactions, as well as by time and the interaction of time with wash treatment. By the third week, unwashed plants had 33.1% of stems and branch tips scoring >5% coverage with aphids, and 17.9% of unwashed stems and branch tips had 20% or more of their surface area covered by aphids. Washing plants prevented aphid coverage from ever exceeding the 5% class on all module types. In the second experiment, buds and stems with high numbers of aphids before washing generally experienced notable declines with a single wash. When the prewash coverage was 10% or greater, reduction in coverage ranged from 50 to 100% of the prewash amount. In 64% of the cases, the reduction in coverage was 75% or more of the prewash amount. Plant washing can provide a viable means of management for small, soft-bodied arthropods such as aphids.

Animals↗
PubMed2004

[Obtainment of transgenic wheat with the insecticidal lectin from snowdrop (Galanthus nivalis agglutinin; GNA) gene and analysis of resistance to aphid].

Snowdrop lectin (Galanthus nivalis agglutinin; GNA) is toxic to sap sucking injurious insects of Homopteran. A new gna gene has been transferred into common spring wheat Zhong60634 and winter wheat Yumai66 with high yield by using the biolistic transformation method. Transgenic wheat plants have been obtained in both of the two varieties. Two transgenic plants (T0) have been obtained from the bombarded 535 immature embryos of Zhong60634. Bioassay results show that the development of aphid could be slowed down and the survival rate of young aphid could be reduced by gna gene. Seventeen transgenic plants (T0) were obtained from the bombarded 4636 immature embryos of Yumai66. Twenty plantlets with good resistance to Rhopalosiphum padi and Macrosiphum avenae, which are mainly aphid in north wheat area, were identified from the transgenic plants of T1 generation that came from 8 T0 transgenic plants with good resistance to aphid. The anti-aphid bioassay shows that resistance to the different grain aphid is not the same in transgenic wheat plants. To Rhopalosiphum padi, the rate of survival aphid 8 days after exposing transgenic plants to aphids is significantly lower than that of nontransgenic plants. To Macrosiphum avenae, growth speed of aphids is slowed down but not killed. At the same time, the death rate of young aphids is increased. Anyway, feeding of the two kinds of aphids has been controlled in a certain degree by gna gene when aphids can free to move in plants.

Animals↗
PubMed2003

Manipulation of parasitoids for aphid pest management: progress and prospects.

This paper describes research at IACR-Rothamsted on aphid parasitoid responses to semiochemical foraging stimuli, aimed at developing novel ways of manipulating these behaviours to overcome ecological constraints to biological and integrated pest control. Female parasitoids respond both to aphid sex pheromones acting as kairomones, and to aphid-induced plant volatiles, acting as synomones. A range of economically important parasitoid species respond to aphid sex pheromones, and their potential for enhancing parasitization of aphid populations has been demonstrated in the field. Commercial production of the pheromone from the plant Nepeta cataria L has been developed and strategies for its use in arable crops are being investigated. Aphid-induced plant volatiles are released systemically throughout the plant and are aphid species specific, probably induced by elicitors in aphid saliva. Aphid-infested plants can induce uninfested neighbours to release damage-related volatiles, plant-to-plant communication occurring via the rhizosphere. The plant compound cis-jasmone has been identified as a plant signal with potential for aphid control, inducing plant defence mechanisms that both deter colonising aphids and attract parasitoids and predators. Such compounds may represent a new generation of crop protectants and their further investigation and development will be aided by the tools generated by genomic and post-genomic biology.

Animals↗
PubMed2003

Glutenin and gliadin contents of flour derived from wheat infested with different aphid species.

Aphid feeding in cereals results in both quantitative and qualitative yield losses; moreover aphid-transmitted viruses are responsible for other quantitative and qualitative damage so that direct or indirect effects of aphid infection are always of interest. At the beginning of stem elongation, wheat plants were caged regardless of the presence or absence of indigenous cereal aphids. Half of the caged plants were artificially infected with Diuraphis noxia. The number of D noxia and Rhopalosiphum padi individuals on plants destined for flour preparation was approximately 150 aphids per tiller at peak population. The number of Sitobion avenae individuals was ca 25 aphids per tiller. Bread-making quality of wheat flour is determined primarily by the protein content, the gluten proteins (gliadins, glutenins) being the prime factors. The absolute amounts and/or the relative proportion of gliadins and glutenins are very important in dough making and in determining baking quality. Flour from grains originating from plants infected naturally with cereal aphids indigenous to Hungary, and flour infected artificially with D noxia, were analysed for glutenin and gliadin content using size exclusion HPLC. It was found that aphid infection had a significant effect on the gliadin/glutenin ratio, which was significantly lower in wheat flour prepared from aphid-infected plants than in that from uninfected control. The most significant decrease in gliadin/glutenin ratio was caused by D noxia infection, followed by R padi and then S avenae. As the gliadin/glutenin ratio was significantly lower in flour made from aphid-infected wheat seeds, it can be supposed that aphid feeding results in decreased bread making quality of wheat flour.

Animals↗
PubMed1997

Occurrence and transmission of facultative endosymbionts in aphids.

The occurrence of a secondary bacterial symbiont (PASS) of pea aphid, Acyrthosiphon pisum (Harris), was detected by polymerase chain reaction (PCR) with specific nucleotide primers based on PASS 16S rDNA nucleotide sequences from over 80% (50/57) of clones of pea aphid collected from widely separated locations in California. PASS was also detected by PCR in both red and green phenotypes of rose aphid,Macrosiphum rosae (L.), but not in six other species of aphids examined, including blue alfalfa aphid (A. kondoi Shinji). The nucleotide sequences of the PCR-amplified, partial 16S rDNAs (1060 bp) from pea aphid and rose aphid were identical and 99.9% similar to the published 16S rDNA of PASS. PASS and a recently described new rickettsia of pea aphid (PAR) were transmitted by needle injection of hemolymph from positive pea aphid clones into negative clones and into blue alfalfa aphids. Both PASS and PAR were maintained in the offspring of some of the injected mother aphids via high rate of maternal transmission.

Animals↗