Publications

probiotic effect of lactobacillus sp. ds-12 in flounder (paralichthys olivaceus).	pea aphids were reared aseptically in the laboratory and fed on strains of erwinia aphidicola, erwinia herbicola, klebsiella pneumoniae, escherichia coli and bacterium w, an aphid enterobacterium, by mixing with a synthetic diet to determine whether these bacteria have pathogenicity to the insect. it turned out that er. aphidicola and er. herbicola grew in aphid gut, while k. pneumoniae, es. coli and bacterium w were effectively eliminated. in the case of er. aphidicola, ingestion of a single do ...	1997	12501308
nutritional plasticity of the predatory ladybeetle harmonia axyridis (coleoptera: coccinellidae): comparison between natural and substitution prey.	the predatory coccinellid harmonia axyridis is a polyphagous species, efficient at controlling certain aphid species and already commercialized in europe for that purpose. the complete development of this predator can be accomplished using the aphid acyrthosiphon pisum or ephestia kuehniella eggs as substitution prey. biochemical analyses were conducted on the proteins, lipids, and carbohydrates of these two different prey species. e. kuehniella eggs were 2 times richer in amino acids than a. pi ...	2003	12529863
a comparison of parthenogenetic and sexual embryogenesis of the pea aphid acyrthosiphon pisum (hemiptera: aphidoidea).	aphids exhibit divergent modes of embryogenesis during the sexual and asexual phases of the life cycle. to explore how a single genome can give rise to these alternative developmental modes, we have initiated embryological studies of the pea aphid, acyrthosiphon pisum. here we present a detailed description of parthenogenetic, viviparous embryonic development in the pea aphid. we compare and contrast development of the parthenogenetic embryo with that of the embryo resulting from sexual reproduc ...	2003	12548543
facultative bacterial symbionts in aphids confer resistance to parasitic wasps.	symbiotic relationships between animals and microorganisms are common in nature, yet the factors controlling the abundance and distributions of symbionts are mostly unknown. aphids have an obligate association with the bacterium buchnera aphidicola (the primary symbiont) that has been shown to contribute directly to aphid fitness. in addition, aphids sometimes harbor other vertically transmitted bacteria (secondary symbionts), for which few benefits of infection have been previously documented. ...	2003	12563031
selection by phage display of a variant mustard trypsin inhibitor toxic against aphids.	the mustard trypsin inhibitor, mti-2, is a potent inhibitor of trypsin with no activity towards chymotrypsin. mti-2 is toxic for lepidopteran insects, but has low activity against aphids. in an attempt to improve the activity of the inhibitor towards aphids, a library of inhibitor variants was constructed and cloned into the prlac3 phagemid vector. the library of 9.3 x 107 independent colonies was created by randomisation of a stretch of five consecutive codons in the reactive site. repeated sel ...	2003	12581313
identification of a gene overexpressed in aphids reared under short photoperiod.	most aphids develop a cyclic parthenogenesis life-cycle. after several generations of viviparously produced parthenogenetic females, follows a single annual generation of sexual individuals, usually in autumn, that mate and lay the sexual eggs. shortening of photoperiod at the end of the summer (together with temperature) is a key factor inducing the sexual response. currently no genes involved in the cascade of events that lead to the appearance of sexual forms have been reported. after a diffe ...	2003	12609514
toxicity to the pea aphid acyrthosiphon pisum of anti-chymotrypsin isoforms and fragments of bowman-birk protease inhibitors from pea seeds.	aphids feed on a protein-poor diet and are insensitive to several serine protease inhibitors. however, among the bowman-birk family of plant trypsin inhibitors (bbi), some members display significant toxicity to the pea aphid acyrthosiphon pisum. a bbi isoform purified from pea seeds (psti-2) displays an ic50 of 41 microm and a lc50 of 48 microm at 7 days. our data show that the chymotrypsin-directed active site from these bifunctional inhibitors is responsible for this activity, and that artifi ...	2003	12609515
costs of resistance in insect-parasite and insect-parasitoid interactions.	most, if not all, organisms face attack by natural enemies and will be selected to evolve some form of defence. resistance may have costs as well as its obvious benefits. these costs may be associated with actual defence or with the maintenance of the defensive machinery irrespective of whether a challenge occurs. in this paper, the evidence for costs of resistance in insect-parasite and insect-parasitoid systems is reviewed, with emphasis on two host-parasitoid systems, based on drosophila mela ...	2002	12622330
effect of spatial heterogeneity on the role of coccinella septempunctata as an intra-guild predator of the aphid pathogen pandora neoaphidis.	the foraging behavior of starved and non-starved adult and larval coccinella septempunctata on groups of plants in the presence of pandora neoaphidis-infected acyrthosiphon pisum, uninfected aphids or a mixture of these two prey types was compared. in general results of these studies confirmed the results of previous work comparing foraging behavior on a smaller spatial scale in petri dishes. however, behaviors were modified in response to spatial complexity, prey quality, and the host plant. st ...	2003	12623308
a novel computerised image analysis method for the measurement of production of conidia from the aphid pathogenic fungus erynia neoaphidis.	a semi-automated method has been developed for the quantification and measurement of conidia discharged by the aphid pathogen erynia neoaphidis. this was used to compare conidiation by e. neoaphidis-mycosed pea aphid cadavers, mycelial plugs cut from agar plates, mycelial pellets from shake flasks and by mycelial pellets from different phases of liquid batch fermenter culture. aphid cadavers discharged significantly more and significantly smaller conidia than plugs or pellets. the volume of coni ...	2003	12644230
effects of a simple plant morphological mutation on the arthropod community and the impacts of predators on a principal insect herbivore.	plant features that enhance predator effectiveness can be considered extrinsic-resistance factors because they result in reduced insect herbivory. in this paper we test the hypothesis that reduced epicuticular wax (ew) in pisum sativum l. is an extrinsic-resistance factor contributing to field resistance to acyrthosiphon pisum (harris). we monitored pea aphid populations in the field on reduced ew and normal ew near isolines of peas for two seasons and confirmed that aphid populations are lower ...	2003	12647102
extraordinary proliferation of microorganisms in aposymbiotic pea aphids, acyrthosiphon pisum.	aposymbiotic pea aphids, which were deprived of their intracellular symbiotic bacterium, buchnera, exhibit growth retardation and no fecundity. high performance liquid chromatographic (hplc) analysis revealed that these aposymbiotic aphids, when reared on broad bean plants, accumulated a large amount of histamine. to assess the possibility of extraordinary proliferation of microorganisms other than buchnera, we enumerated eubacteria and fungi in aphids using the real-time quantitative pcr method ...	2003	12676551
the interplay between density- and trait-mediated effects in predator-prey interactions: a case study in aphid wing polymorphism.	natural enemies not only influence prey density but they can also cause the modification of traits in their victims. while such non-lethal effects can be very important for the dynamic and structure of prey populations, little is known about their interaction with the density-mediated effects of natural enemies. we investigated the relationship between predation rate, prey density and trait modification in two aphid-aphid predator interactions. pea aphids (acyrthosiphon pisum, harris) have been ...	2003	12698353
characterization of a high-affinity binding site for the pea albumin 1b entomotoxin in the weevil sitophilus.	the toxicity of the pea albumin 1b (pa1b), a 37 amino-acid peptide extracted from pea seeds, for cereal weevils (sitophilus oryzae, sitophilus granarius and sitophilus zeamais) was recently discovered. the mechanism of action of this new entomotoxin is still unknown and potentially involves a target protein in the insect tissues. this work describes the characterization of a high-affinity binding site for pa1b in a microsomal fraction of sitophilus spp. extracts. purified pa1b was labeled to a h ...	2003	12755698
host regulation effects of ovary fluid and venom of aphidius ervi (hymenoptera: braconidae).	the host regulation effects of venom and ovary fluid of the endophagous braconid aphidius ervi haliday on the pea aphid, acyrthosiphon pisum (harris), have been studied. extracts of ovaries and of venom glands were injected into nonparasitized 4th instar pea aphids, both separately and mixed. aphids treated with parasitoid material died as 4th instars, often showing developmental arrest. in contrast, control aphids that received an injection of pringle's saline solution regularly moulted to the ...	1998	12769873
host cell allometry and regulation of the symbiosis between pea aphids, acyrthosiphon pisum, and bacteria, buchnera.	the symbiotic bacteria buchnera in aphids are borne in cells, called bacteriocytes, in the insect haemocoel. the number and median volume of bacteriocytes in pre-reproductive adult insects varied significantly among 14 parthenogenetic clones of the pea aphid acyrthosiphon pisum. after logarithmic transformation of the data, the relationship of both number and median volume of bacteriocytes with aphid weight for the clones could be described by common regression lines with slopes significantly gr ...	1998	12769945
melatonin and the pea aphid, acyrthosiphon pisum.	pea aphids, acyrthosiphon pisum, were fed on artificial diet containing various concentrations of melatonin. under long-day conditions (16h light:8h dark) their progeny included males and virginoparous/oviparous (asexual/sexual) intermediate females, which normally occur only in short days or around critical night-length. endogenous melatonin in pea aphids was measured by radioimmunoassay and verified by parallelism with a melatonin standard curve and by thin layer chromatography. however, melat ...	1997	12769971
midgut adaptation and digestive enzyme distribution in a phloem feeding insect, the pea aphid acyrthosiphon pisum.	transmission electron micrographs of the pea aphid midgut revealed that its anterior region has cells with an apical complex network of lamellae (apical lamellae) instead of the usual regularly-arranged microvilli. these apical lamellae are linked to one another by trabeculae. modified perimicrovillar membranes (mpm) are associated with the lamellae and project into the lumen. trabeculae and mpm become less conspicuous along the midgut. the most active a. pisum digestive enzymes are membrane-bou ...	2003	12770012
pea aphid clonal resistance to the endophagous parasitoid aphidius ervi.	the physiological mechanism of resistance to the endophagous braconid aphidius ervi haliday (hymenoptera, braconidae) by a pink clone (pc) of acyrthosiphon pisum (harris) (homoptera, aphididae) has been investigated. comparative data on parasitoid development and associated host biochemical changes in the resistant pc aphids and in a susceptible green clone (gc) of a. pisum are reported. when the pc aphids were attacked as early 4th instars, the developing parasitoid larvae showed a strongly red ...	2002	12770044
metabolic and symbiotic interactions in amino acid pools of the pea aphid, acyrthosiphon pisum, parasitized by the braconid aphidius ervi.	aphidius ervi haliday (hymenoptera, braconidae) is an endophagous parasitoid of the pea aphid, acyrthosiphon pisum (harris) (homoptera, aphididae). this parasitoid strongly redirects host reproduction and metabolism to favour nutrition and development of its juvenile stages. parasite-regulated biosynthesis and mobilization of nitrogen metabolites determine a significant increase of host nutritional suitability. the aim of the present study was mainly to investigate the temporal changes of a. pis ...	2002	12770078
living on a high sugar diet: the fate of sucrose ingested by a phloem-feeding insect, the pea aphid acyrthosiphon pisum.	the natural diet of aphids, plant phloem sap, generally contains high concentrations of sucrose. when pea aphids (acyrthosiphon pisum) were fed on chemically defined diets containing sucrose radiolabelled in the glucose or fructose moiety, 2 to 12-fold and 87 to 110-fold more radioactivity was recovered from the tissues and honeydew, respectively, of aphids that ingested [u-(14)c-glucose]-sucrose than from those ingesting [u-(14)c-fructose]-sucrose. the total radioactivity recovered was 70% of t ...	2000	12770238
provision of riboflavin to the host aphid, acyrthosiphon pisum, by endosymbiotic bacteria, buchnera.	differential cdna display and quantitative rt-pcr suggested that the riboflavin synthase complex of the aphid endosymbiont, buchnera, is active only when the symbiotic system is maintained and well organized in young hosts. since this finding suggested the provision of riboflavin by buchnera, we examined the effect of dietary riboflavin on the performance of symbiotic and aposymbiotic aphids using chemically-defined diets. our results indicate: (1) dietary riboflavin is slightly detrimental to y ...	1999	12770389
xerocomus chrysenteron lectin: identification of a new pesticidal protein.	xerocomus chrysenteron is an edible mushroom with insecticidal properties. in an earlier work, we found that proteins are responsible for this toxicity. here we describe the purification of a approximately 15 kda lectin, named xcl, from the mushroom. its cdna and gdna were cloned by pcr strategies and a recombinant form was expressed in escherichia coli. sequence alignments and sugar specificity showed that this protein is the third member of a new saline-soluble lectin family present in fungi. ...	2003	12787928
elucidation of the transmission patterns of an insect-borne bacterium.	quantitative data on modes of transmission are a crucial element in understanding the ecology of microorganisms associated with animals. we investigated the transmission patterns of a gamma-proteobacterium informally known as pea aphid bemisia-like symbiont (pabs), also known as t-type, which is widely but not universally distributed in natural populations of the pea aphid, acyrthosiphon pisum. the vertical transmission of pabs to asexual and sexual morphs and sexually produced eggs was demonstr ...	2003	12902222
diapause in the pea aphid (acyrthosiphon pisum) is a slowing but not a cessation of development.	many insects undergo a period of arrested development, called diapause, to avoid seasonally recurring adverse conditions. whilst the phenology and endocrinology of insect diapause have been well studied, there has been comparatively little research into the developmental details of diapause. we investigated developmental aspects of diapause in sexually-produced embryos of the pea aphid, acyrthosiphon pisum.	2003	12908880
host-based divergence in populations of the pea aphid: insights from nuclear markers and the prevalence of facultative symbionts.	in north america, the pea aphid acyrthosiphon pisum encompasses ecologically and genetically distinct host races that offer an ideal biological system for studies on sympatric speciation. in addition to its obligate symbiont buchnera, pea aphids harbour several facultative and phylogenetically distant symbionts. we explored the relationships between host races of a. pisum and their symbiotic microbiota to gain insights into the historical process of ecological specialization and symbiotic acquis ...	2003	12964998
the latent period of pea-enation mosaic virus in the pea aphid, acyrthosiphon pisum (harris)--an approach to its estimation.		1965	14277086
total glycogen in the pea aphid, acyrthosiphon pisum (harr.) (homoptera, aphididae).		1965	14322426
oxidation of carbohydrates by the pea aphid, macrosiphum pisi (kltb.).		1955	14367361
developmental origin and evolution of bacteriocytes in the aphid-buchnera symbiosis.	symbiotic relationships between bacteria and insect hosts are common. although the bacterial endosymbionts have been subjected to intense investigation, little is known of the host cells in which they reside, the bacteriocytes. we have studied the development and evolution of aphid bacteriocytes, the host cells that contain the endosymbiotic bacteria buchnera aphidicola. we show that bacteriocytes of acyrthosiphon pisum express several gene products (or their paralogues): distal-less, ultrabitho ...	2003	14551917
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 tax ...	2003	14660369
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 consider ...	2003	14667385
the population genetics of a biological control introduction: mitochondrial dna and microsatellie variation in native and introduced populations of aphidus ervi, a parisitoid wasp.	introductions of biological control agents may cause bottlenecks in population size despite efforts to avoid them. we examined the population genetics of aphidius ervi (hymenoptera: braconidae), a parasitoid that was introduced to north america from western europe in 1959 to control pea aphids. to explore the phylogeographical relationships of a. ervi we sequenced 1249 bp of mitochondrial dna (mtdna) from 27 individuals from the native range and 51 individuals from the introduced range. most ind ...	2004	14717891
plant waxy bloom on peas affects infection of pea aphids by pandora neoaphidis.	this study examined the effects of the surface wax bloom of pea plants, pisum sativum, on infection of pea aphids, acyrthosiphon pisum, by the fungal pathogen pandora neoaphidis. in prior field surveys, a higher proportion of p. neoaphidis-killed pea aphids (cadavers) had been observed on a pea line with reduced wax bloom, as compared with a sister line with normal surface wax bloom. laboratory bioassays were conducted in order to examine the mechanisms. after plants of each line infested with a ...	2003	14726238
changing partners in an obligate symbiosis: a facultative endosymbiont can compensate for loss of the essential endosymbiont buchnera in an aphid.	almost all aphids harbour an endosymbiotic bacterium, buchnera aphidicola, in bacteriocytes. buchnera synthesizes essential nutrients and supports growth and reproduction of the host. over the long history of endosymbiosis, many essential genes have been lost from the buchnera genome, resulting in drastic genome reduction and the inability to live outside the host cells. in turn, when deprived of buchnera, the host aphid suffers retarded growth and sterility. buchnera and the host aphid are ofte ...	2003	14728775
delineating the effects of a plant trait on interactions among associated insects.	plant traits can affect ecological interactions between plants, herbivores, and predators. our study tests whether reduced leaf wax in peas alters the interaction between the pea aphid ( acyrthosiphon pisum), a foliar-foraging predator (a lady beetle, hippodamia convergens) and a ground-foraging predator (a ground beetle, poecilus scitulus). we performed a 2 x 2 x 2 factorial experiment in which wax level, presence of h. convergens, and presence of p. scitulus were manipulated. experimental aren ...	2004	14740292
rapid quantification of juvenile hormones and their metabolites in insect haemolymph by liquid chromatography-mass spectrometry (lc-ms).	a simple, fast and sensitive method was developed for routine determination of juvenile hormone (jh), jh diols and jh acids in insect haemolymph, by liquid chromatography-mass spectrometry (lc-ms). sample clean-up involves the precipitation of proteins by methanol/isooctane (1:1, v/v), centrifugation and partial evaporation of the organic solvents. since jh is bound to a carrier protein in the haemolymph, a binding protein (bp) assay was performed to ensure jh is removed during precipitation. th ...	2004	15057500
air pollution and agricultural aphid pests. ii chamber filtration experiments.	the responses of four major aphid pest species feeding on three major crops were studied in a series of experimental chambers on the roof of imperial college in south kensington, london. the experimental chambers were continually circulated with air which had been subjected to a variety of filtration treatments. in the first series of experiments there were three chambers subject to ambient air, charcoal-filtered air, and charcoal plus 'purafil'-filtered air; in the subsequent experiments there ...	1991	15092113
responses to ozone of insects feeding on a crop and a weed species.	the influence of ozone on insect herbivore growth and population development was investigated. fumigation of both pea (pisum sativum l.) and dock (rumex obtusifolius l.) at a range of o(3) concentrations between 21-206 nl litre(-1) produced changes in mean relative growth rates of the aphids acyrthosiphon pisum harris and aphis rumicis l. of between 24 and -6% relative to controls. however, there was no evidence of a dose-related response to o(3) fumigation and no clear differences in aphid resp ...	1989	15092338
effect of so2 on the reproduction of pea aphids, acyrthosiphon pisum, and the impact of so2 and aphids on the growth and yield of peas.	pea aphids feeding from birth to maturity on pea plants (pisum sativum) exposed to so(2) concentrations of 50 nl litre(-1) or 80 nl litre(-1) showed a significant 19% increase in the rate of nymph production during the reproductive period, compared to control aphids feeding on plants in charcoal-filtered air. the higher nymph production resulted in a mean 4.6% increase in the intrinsic rate of population increase (rm). in longer term glasshouse fumigation experiments pea aphid populations were, ...	1987	15092679
relationship between so2 dose and growth of the pea aphid, acyrthosiphon pisum, on peas.	a series of experiments was carried out in controlled environment cabinets to investigate the effects of so(2) dose on the mean relative growth rate (mrgr) of pea aphids, acyrthosiphon pisum, feeding on the pea plant, pisum sativum. there was a significant linear increase in the mrgr of aphids feeding on so(2)-fumigated plants, relative to control aphids feeding on plants in charcoal-filtered air. the increase in mrgr reached a maximum of 11% at so(2) concentrations between 90 and 110 nl litre(- ...	1987	15092808
olfactory responses to aphid and host plant volatile releases: (e)-beta-farnesene an effective kairomone for the predator adalia bipunctata.	the volatiles released from several aphid and host plant species, alone or associated, were studied for their infochemical role in prey location. using a four-arm olfactometer, the attraction of several combinations of three aphid (myzus persicae, acyrthosiphon pisum, and brevicoryne brassicae) and three plant (vicia faba, brassica napus, and sinapis alba) species toward adalia bipunctata larvae and adults was observed. both predatory larvae and adults were attracted only by a. pisum and m. pers ...	2004	15260221
the role of semiochemicals in the avoidance of the seven-spot ladybird, coccinella septempunctata, by the aphid parasitoid, aphidius ervi.	the role of semiochemicals in mediating intraguild interactions between the seven-spot ladybird, coccinella septempunctata, and the aphid parasitoid, aphidius ervi, was investigated. female parasitoids avoided leaves visited by c. septempunctata adults and larvae during the previous 24 hr. ethanol extracts of c. septempuntata adults and larvae also induced avoidance responses by a. ervi. two of the hydrocarbons identified by gas chromatography (gc) and coupled gc-mass spectrometry (gc-ms), n-tri ...	2004	15303317
the evolutionary fate of nonfunctional dna in the bacterial endosymbiont buchnera aphidicola.	reduction of the genome size in endosymbiotic bacteria is the main feature linked to the adaptation to a host-associated lifestyle. we have analyzed the fate of the nonfunctional dna in buchnera aphidicola, the primary endosymbiont of aphids. at least 164 gene losses took place during the recent evolution of three b. aphidicola strains, symbionts of the aphids acyrthosiphon pisum (bap), schizaphis graminum (bsg), and baizongia pistacia (bbp). a typical pattern starts with the inactivation of a g ...	2004	15317875
individual and population variation in invertebrates revealed by inter-simple sequence repeats (issrs).	pcr-based molecular markers are well suited for questions requiring large scale surveys of plant and animal populations. inter-simple sequence repeats or issrs are analyzed by a recently developed technique based on the amplification of the regions between inverse-oriented microsatellite loci with oligonucleotides anchored in microsatellites themselves. issrs have shown much promise for the study of the population biology of plants, but have not yet been explored for similar studies of animals. ...	2001	15455068
per os efficacy of ajuga extracts against sucking insects.	we studied the efficacy of water-soluble extracts from four ajuga spp on the post-embryonic development of two exopterygota (sucking insect) species. to allow comparison between different ajuga species, results are expressed in terms of quantity of plant extracted per litre of test solution. crude methanolic extracts of all ajuga plants tested, with the exception of a genevensis, showed considerable per os efficacy against larvae of both dysdercus cingulatus f and acyrthosiphon pisum (harris) ev ...	2004	15532684
aster self-organization at meiosis: a conserved mechanism in insect parthenogenesis?	unfertilized eggs usually lack maternal centrosomes and cannot develop without sperm contribution. however, several insect species lay eggs that develop to adulthood as unfertilized in the absence of a preexisting centrosome. we report that the oocyte of the parthenogenetic viviparous pea aphid acyrthosiphon pisum is able to self-organize microtubule-based asters, which in turn interact with the female chromatin to form the first mitotic spindle. this mode of reproduction provides a good system ...	2005	15649474
binding of the insecticidal lectin concanavalin a in pea aphid, acyrthosiphon pisum (harris) and induced effects on the structure of midgut epithelial cells.	concanavalin a (lectin from canavalia ensiformis l., cona) has previously been shown to act as a feeding inhibitor for acyrthosiphon pisum, the pea aphid. in the present study a range of histochemical and biochemical techniques were used to elucidate the target tissues and binding sites of the lectin in the aphid. diet uptake was evaluated using a radioactive tracer (14c-methylated inulin) and demonstrated that adults were capable of ingesting high quantities of the toxin (approx. 1 microg over ...	2004	15670861
genetic mapping of aphicarus -- a sex-linked locus controlling a wing polymorphism in the pea aphid (acyrthosiphon pisum).	we have initiated research to determine the genetic basis of a male wing polymorphism in the pea aphid acyrthosiphon pisum (hemiptera: aphididae). previous studies showed that this polymorphism is controlled by a single biallelic locus, which we name aphicarus (api), on the x chromosome. our objectives were to confirm that api segregates as a polymorphism of a single gene on the x chromosome, and to obtain molecular markers flanking api that can be used as a starting point for high-resolution ge ...	2005	15674387
characterization of a facultative endosymbiotic bacterium of the pea aphid acyrthosiphon pisum.	the pea aphid u-type symbiont (paus) was investigated to characterize its microbiological properties. fluorescence in situ hybridization (fish) and electron microscopy revealed that paus was a rod-shaped bacterium found in three different locations in the body of the pea aphid acyrthosiphon pisum: sheath cells, secondary mycetocytes, and hemolymph. artificial transfer experiments revealed that paus could establish stable infection and vertical transmission when introduced into uninfected pea aph ...	2005	15690225
aphid infestation causes different changes in carbon and nitrogen allocation in alfalfa stems as well as different inhibitions of longitudinal and radial expansion.	alfalfa (medicago sativa) stem elongation is strongly reduced by a pea aphid (acyrthosiphon pisum harris) infestation. as pea aphid is a phloem feeder that does not transmit virus or toxins, assimilate withdrawal is generally considered as the main mechanism responsible for growth reduction. using a kinematic analysis, we investigated the spatial distributions of relative elemental growth rates of control and infested alfalfa stems. the water, carbon, and nitrogen contents per unit stem length w ...	2005	15778456
a novel fatty acid binding protein produced by teratocytes of the aphid parasitoid aphidius ervi.	aphidius ervi is an endophagous braconid, parasitoid of the pea aphid, acyrthosiphon pisum. a. ervi teratocytes, deriving from the dissociation of the embryonic serosa, synthesize and release two major proteins into the host haemocoel. the gene of one of these proteins has been cloned and characterized. this gene codes for a 15.8 kda protein belonging to the fatty acid binding protein (fabp) family, named ae-fabp (a. ervi-fabp). it is abundantly present in the host haemolymph when the parasitoid ...	2005	15796753
transcriptome analysis of the aphid bacteriocyte, the symbiotic host cell that harbors an endocellular mutualistic bacterium, buchnera.	aphids possess bacteriocytes, cells specifically differentiated to harbor obligatory mutualistic bacteria of the genus buchnera, which have lost many genes that are essential for common bacterial functions. to understand the host's role in maintaining the symbiotic relationship, bacteriocytes were isolated from the pea aphid, acyrthosiphon pisum, and the host transcriptome was investigated by using est analysis and real-time quantitative rt-pcr. a number of genes were highly expressed specifical ...	2005	15800043
attraction of two lacewing species to volatiles produced by host plants and aphid prey.	it is well documented that host-related odors enable many species of parasitoids and predatory insects to locate their prey and prey habitats. this study reports the first characterization of prey and prey host odor reception in two species of lacewings, chrysoperla carnea (say) and chrysopa oculata l. 2-phenylethanol, one of the volatiles emitted from their prey's host plants (alfalfa and corn) evoked a significant eag response from antennae of c. carnea. traps baited with this compound attract ...	2005	15812573
genetic variation for an aphid wing polyphenism is genetically linked to a naturally occurring wing polymorphism.	many polyphenisms are examples of adaptive phenotypic plasticity where a single genotype produces distinct phenotypes in response to environmental cues. such alternative phenotypes occur as winged and wingless parthenogenetic females in the pea aphid (acyrthosiphon pisum). however, the proportion of winged females produced in response to a given environmental cue varies between clonal genotypes. winged and wingless phenotypes also occur in males of the sexual generation. in contrast to parthenog ...	2005	15817441
prodrug-oriented molecular design of neonicotinoids: preparation of imidacloprid-related 5,5-dimethoxy-1,3-diazacyclohexane derivatives and their insecticidal activity.	prodrug-oriented molecular design was attempted for the potent acyclic neonicotinoid insecticide, clothianidin (1-(2-chloro-5-thiazolylmethyl)-3-methyl-2-nitroguanidine). molecules bearing a ch2coch2 bridge linking the 1,3-nh ends of clothianidin or their acetals would possibly be hydrolyzed, regenerating the mother compounds. this strategy was used to prepare seven acetals of clothianidin-based molecules that combined 2-chloro-5-thiazolylmethyl, 6-chloro-3-pyridylmethyl or 3-tetrahydrofurfuryl ...	2005	15849408
arthropod diversity in peas with normal or reduced waxy bloom.	crop traits can alter economically important interactions between plants, pests, and biological control agents. for example, a reduced waxy bloom on the surface of pea plants alters interactions between pea aphids and their natural enemies. in this study, we assess whether the effect of wax reduction extends beyond the 2 or 3 arthropod species closely associated with the plants and into the structure of the broader arthropod community of over 200 taxa at our site. we sampled arthropods on lines ...	2004	15861234
the importance of antennae for pea aphid wing induction in the presence of natural enemies.	the pea aphid acyrthosiphon pisum harris has been shown to produce an increasing proportion of winged morphs among its offspring when exposed to natural enemies, in particular hoverfly larvae, lacewing larvae, adult and larval ladybirds and aphidiid parasitoids. while these results suggest that wing induction in the presence of predators and parasitoids is a general response of the pea aphid, the cues and mechanisms underlying this response are still unclear. tactile stimuli and the perception o ...	2005	15877861
back to the future: genetic correlations, adaptation and speciation.	genetic correlations can affect the course of phenotypic evolution. although genetic correlations among traits are a common feature of quantitative genetic analyses, they have played a very minor role in recent linkage-map based analyses of the genetic architecture of quantitative traits. here, we use our work on host-associated races in pea aphids to illustrate how quantitative trait locus (qtl) mapping can be used to test specific hypotheses about how genetic correlations may facilitate ecolog ...	2005	15881687
effect of precocene ii on fatty acid metabolism in the pea aphid, acyrthosiphon pisum, under cold stress.	pea aphids, acyrthosiphon pisum (harris), reared at 10 degrees c contain higher levels of fatty acids than those reared at 25 degrees c. this is primarily the result of an accumulation of triacylglycerols containing myristic acid. when aphids reared at 25 degrees c were transferred to 10 degrees c there was a gradual increase in triacylglycerol content that reached a maximum at 16 days post-transfer. treatment of aphids with precocene ii prior to transfer to 10 degrees c blocked the accumulation ...	2005	15890184
regulation of transcription in a reduced bacterial genome: nutrient-provisioning genes of the obligate symbiont buchnera aphidicola.	buchnera aphidicola, the obligate symbiont of aphids, has an extremely reduced genome, of which about 10% is devoted to the biosynthesis of essential amino acids needed by its hosts. most regulatory genes for these pathways are absent, raising the question of whether and how transcription of these genes responds to the major shifts in dietary amino acid content encountered by aphids. using full-genome microarrays for b. aphidicola of the host schizaphis graminum, we examined transcriptome respon ...	2005	15937185
rickettsia symbiont in the pea aphid acyrthosiphon pisum: novel cellular tropism, effect on host fitness, and interaction with the essential symbiont buchnera.	in natural populations of the pea aphid acyrthosiphon pisum, a facultative bacterial symbiont of the genus rickettsia has been detected at considerable infection frequencies worldwide. we investigated the effects of the rickettsia symbiont on the host aphid and also on the coexisting essential symbiont buchnera. in situ hybridization revealed that the rickettsia symbiont was specifically localized in two types of host cells specialized for endosymbiosis: secondary mycetocytes and sheath cells. e ...	2005	16000822
response of the entomopathogenic fungus pandora neoaphidis to aphid-induced plant volatiles.	we used a model plant-aphid system to investigate whether the aphid-specific entomopathogenic fungus pandora neoaphidis responds to aphid-induced defence by the broad-bean plant, vicia faba. laboratory experiments indicated that neither in vivo sporulation, conidia size nor the in vitro growth of p. neoaphidis was affected by acyrthosiphon pisum-induced v. faba volatiles. the proportion of conidia germinating on a. pisum feeding on previously damaged plants was significantly greater than on aphi ...	2005	16005016
pandora neoaphidis transmission and aphid foraging behaviour.	pandora neoaphidis is an aphid-specific entomopathogen that produces infective conidia. as aphid movement increases, so does the likelihood of contact with conidia. volatile distress signals released in response to aphid infestation as an indirect defence against herbivory may affect aphid foraging and, therefore, the fungus-aphid interaction. in this study, two different methods were used to investigate the effect of plant volatiles and p. neoaphidis-sporulating cadavers on (1) the colonisation ...	2005	16039666
response of economically important aphids to components of hemizygia petiolata essential oil.	the essential oil of hemizygia petiolata ashby (lamiaceae) contains high levels (>70%) of the sesquiterpene (e)-beta-farnesene, the alarm pheromone for many economically important aphid species. in order to test the suitability of h. petiolata oil as a source of (e)-beta-farnesene for use in new integrated aphid control strategies, behavioural responses of pest aphid species were studied in laboratory and field experiments. in alarm pheromone assays the peach-potato aphid, myzus persicae sulzer, ...	2005	16059962
nutrient absorption by aphidius ervi larvae.	it is well documented that in the model system aphidius ervi haliday (hymenoptera, braconidae)/acyrthosiphon pisum (harris) (homoptera, aphididae) host regulation by the parasitoid larva induces in the aphid haemolymph major changes of the titer of nutritional compounds such as proteins, acylglycerols and free amino acids, in order to meet the stage-specific demands of the developing larva. since little is known about how the larva absorbs these mobilized nutritional resources, nutrient absorpti ...	2005	16085087
resistance is costly: trade-offs between immunity, fecundity and survival in the pea aphid.	parasitoids are among the most important natural enemies of insects in many environments. acyrthosiphon pisum, the pea aphid, is a common pest of the leguminous crops in temperate regions. pea aphids are frequently attacked by a range of endoparasitic wasps, including the common aphidiine, aphidius ervi. immunity to parasitoid attack is thought to involve secondary symbiotic bacteria, the presence of which is associated with the death of the parasitoid egg. it has been suggested that there is a ...	2005	16096092
variation in resistance to parasitism in aphids is due to symbionts not host genotype.	natural enemies are important ecological and evolutionary forces, and heritable variation in resistance to enemies is a prerequisite for adaptive responses of populations. such variation in resistance has been previously documented for pea aphids (acyrthosiphon pisum) attacked by the parasitoid wasp aphidius ervi. although the variation was presumed to reflect genotypic differences among the aphids, another potential source of resistance to a. ervi is infection by the facultative bacterial symbi ...	2005	16120675
development and reproduction of adalia bipunctata (coleoptera: coccinellidae) on eggs of ephestia kuehniella (lepidoptera: phycitidae) and pollen.	due to growing criticism over the use of non-indigenous coccinellids, the two-spot ladybird, adalia bipunctata (l.), has enjoyed increasing attention for aphid biocontrol in europe. in the current study, eggs of the mediterranean flour moth, ephestia kuehniella zeller, whether or not supplemented with bee pollen, were evaluated as a factitious food for larvae and adults of a. bipunctata. the predator showed slower larval development and lower survival when reared on live pea aphids, acyrthosipho ...	2005	16144016
the significance of gut sucrase activity for osmoregulation in the pea aphid, acyrthosiphon pisum.	the osmotic pressure of the body fluids of aphids is lower than in their diet of plant phloem sap. it is hypothesised that aphids reduce the osmotic pressure of ingested food by sucrase-mediated hydrolysis of dietary sucrose to glucose and fructose, and the polymerisation of glucose into oligosaccharides of low osmotic pressure per hexose unit. to test this hypothesis, the impact of the alpha-glucosidase inhibitor acarbose on the sugar relations and osmoregulation of aphids was explored. acarbos ...	2005	16169004
the players in a mutualistic symbiosis: insects, bacteria, viruses, and virulence genes.	aphids maintain mutualistic symbioses involving consortia of coinherited organisms. all possess a primary endosymbiont, buchnera, which compensates for dietary deficiencies; many also contain secondary symbionts, such as hamiltonella defensa, which confers defense against natural enemies. genome sequences of uncultivable secondary symbionts have been refractory to analysis due to the difficulties of isolating adequate dna samples. by amplifying dna from hemolymph of infected pea aphids, we obtai ...	2005	16195380
application of dl-beta-aminobutyric acid (baba) as a root drench to legumes inhibits the growth and reproduction of the pea aphid acyrthosiphon pisum (hemiptera: aphididae).	dl-beta-aminobutyric acid (baba) is a non-protein amino acid that is an effective inducer of resistance against a variety of plant pathogens. however, examples of baba-induced resistance against insect herbivores have not been reported. we applied baba as a soil drench to legumes and monitored its effects on the pea aphid acyrthosiphon pisum (harris). on tic bean (vicia faba var. minor), baba increased aphid mortality, caused a reduction in the mean relative growth rate of individual insects and ...	2005	16197565
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 t ...	2006	16307754
a simple wax-embedding method for isolation of aphid hemolymph for detection of luteoviruses in the hemocoel.	a protocol for isolating hemolymph from viruliferous aphids has been developed. this method uses warm melted wax to immobilize the aphid. following removal of a hind leg, the hemolymph can be collected readily. flushing with rnase-free water allows for collection of sufficient hemolymph for rna extraction from individual aphids. the extracted rna was successfully used for detection of barley yellow dwarf virus (bydv) and pea enation mosaic virus (pemv) from individual viruliferous rhopalosiphum ...	2006	16307802
horizontal transfer of bacterial symbionts: heritability and fitness effects in a novel aphid host.	members of several bacterial lineages are known only as symbionts of insects and move among hosts through maternal transmission. such vertical transfer promotes strong fidelity within these associations, favoring the evolution of microbially mediated effects that improve host fitness. however, phylogenetic evidence indicates occasional horizontal transfer among different insect species, suggesting that some microbial symbionts retain a generalized ability to infect multiple hosts. here we examin ...	2005	16332777
aphid protected from pathogen by endosymbiont.	aphids are associated with several facultative bacterial endosymbionts that may influence their interactions with other organisms. we show here that one of the three most common facultative symbionts of pea aphid (acyrthosiphon pisum), the bacterium regiella insecticola, has a major effect on host resistance to a fungal pathogen. experimental establishment of the bacterium in uninfected aphid clones led to higher survival after fungal attack. the bacteria also increased the aphid's inclusive fit ...	2005	16357252
effect of fungal infection on the reproductive potential of aphids and their progeny.	the effect of infection by pandora neoaphidis and beauveria bassiana on the reproductive potential of the pea aphid, acyrthosiphon pisum, and their progeny was assessed. infection by either p. neoaphidis or b. bassiana reduced the number of nymphs produced within 24 h of inoculation and over the entire infection period compared to uninfected aphids. however, infection by either p. neoaphidis or b. bassiana for 24 or 72 h did not alter the intrinsic rate of increase of the host aphid's progeny. t ...	2006	16410010
phloem-sap feeding by animals: problems and solutions.	the incidence of phloem sap feeding by animals appears paradoxical. although phloem sap is nutrient-rich compared with many other plant products and generally lacking in toxins and feeding deterrents, it is consumed as the dominant or sole diet by a very restricted range of animals, exclusively insects of the order hemiptera. these insects display two sets of adaptations. first, linked to the high ratio of non-essential:essential amino acids in phloem sap, these insects contain symbiotic micro-o ...	2006	16449374
the evolution of the histone methyltransferase gene su(var)3-9 in metazoans includes a fusion with and a re-fission from a functionally unrelated gene.	in eukaryotes, histone h3 lysine 9 (h3k9) methylation is a common mechanism involved in gene silencing and the establishment of heterochromatin. the loci of the major heterochromatic h3k9 methyltransferase su(var)3-9 and the functionally unrelated gamma subunit of the translation initiation factor eif2 are fused in drosophila melanogaster. here we examined the phylogenetic distribution of this unusual gene fusion and the molecular evolution of the h3k9 hmtase su(var)3-9.	2006	16512904
medicago truncatula mutants demonstrate the role of plant calcium oxalate crystals as an effective defense against chewing insects.	calcium oxalate is the most abundant insoluble mineral found in plants and its crystals have been reported in more than 200 plant families. in the barrel medic medicago truncatula gaertn., these crystals accumulate predominantly in a sheath surrounding secondary veins of leaves. mutants of m. truncatula with decreased levels of calcium oxalate crystals were used to assess the defensive role of this mineral against insects. caterpillar larvae of the beet armyworm spodoptera exigua hübner show a c ...	2006	16514014
the phytopathogen dickeya dadantii (erwinia chrysanthemi 3937) is a pathogen of the pea aphid.	dickeya dadantii (erwinia chrysanthemi) is a phytopathogenic bacterium causing soft rot diseases on many crops. the sequencing of its genome identified four genes encoding homologues of the cyt family of insecticidal toxins from bacillus thuringiensis, which are not present in the close relative pectobacterium carotovorum subsp. atrosepticum. the pathogenicity of d. dadantii was tested on the pea aphid acyrthosiphon pisum, and the bacterium was shown to be highly virulent for this insect, either ...	2006	16517643
germ-plasm specification and germline development in the parthenogenetic pea aphid acyrthosiphon pisum: vasa and nanos as markers.	the germarium, oocytes and embryos of the parthenogenetic viviparous pea aphid acyrthosiphon pisum are contained within a single ovariole. this species provides an excellent model for studying how maternally-inherited germ plasm is specified and how it is transferred to primordial germ cells. previous studies have shown that germ cells are first segregated at the embryonic posterior after formation of the blastoderm. we used two cross-reacting antibodies against the conserved germline markers va ...	2006	16525937
partitioning of symbiotic bacteria between generations of an insect: a quantitative study of a buchnera sp. in the pea aphid (acyrthosiphon pisum) reared at different temperatures.	the population of symbiotic buchnera bacteria in parthenogenetic females of the pea aphid acyrthosiphon pisum was determined by quantitative hybridization of a dna probe (groesl) to aphid homogenates. the aphids bore 1 x 10(sup7) to 2 x 10(sup7) bacterial cells per mg (fresh weight). in teneral aphids (i.e., aphids that had moulted to adulthood but that had not initiated reproduction), >75% of the bacteria were in the embryos, and the density of bacteria in the embryos was consistently greater t ...	1997	16535678
a dual-genome microarray for the pea aphid, acyrthosiphon pisum, and its obligate bacterial symbiont, buchnera aphidicola.	the best studied insect-symbiont system is that of aphids and their primary bacterial endosymbiont buchnera aphidicola. buchnera inhabits specialized host cells called bacteriocytes, provides nutrients to the aphid and has co-speciated with its aphid hosts for the past 150 million years. we have used a single microarray to examine gene expression in the pea aphid, acyrthosiphon pisum, and its resident buchnera. very little is known of gene expression in aphids, few studies have examined gene exp ...	2006	16536873
costs and benefits of symbiont infection in aphids: variation among symbionts and across temperatures.	symbiosis is prevalent throughout the tree of life and has had a significant impact on the ecology and evolution of many bacteria and eukaryotes. the benevolence of symbiotic interactions often varies with the environment, and such variation is expected to play an important role in shaping the prevalence and distributions of symbiosis throughout nature. in this study, we examine how the fitness of aphids is influenced by infection with one of three maternally transmitted bacteria, 'candidatus se ...	2006	16537132
attributes of bean yellow mosaic potyvirus transmission from clover to snap beans by four species of aphids (homoptera: aphididae).	after characterization of the natural spread of necrosis-inducing bean yellow mosaic potyvirus (family potyviridae, genus potyvirus, bymv(n)), nonpersistently transmitted from clover, trifolium repens l., to an adjacent field of snap bean, phaseolus vulgaris l., in western oregon, we established a study site enabling us to investigate the virus reservoir, to observe en masse transmission of bymv(n) to bean plants, and to identify aphid species associated with virus spread. colonies of myzus pers ...	2005	16539099
large-scale gene discovery in the pea aphid acyrthosiphon pisum (hemiptera).	aphids are the leading pests in agricultural crops. a large-scale sequencing of 40,904 ests from the pea aphid acyrthosiphon pisum was carried out to define a catalog of 12,082 unique transcripts. a strong at bias was found, indicating a compositional shift between drosophila melanogaster and a. pisum. an in silico profiling analysis characterized 135 transcripts specific to pea-aphid tissues (relating to bacteriocytes and parthenogenetic embryos). this project is the first to address the geneti ...	2006	16542494
effects of hydrophilic and hydrophobic kaolin-based particle films on pea aphid (homoptera: aphididae) and its entomopathogen pandora neoaphidis (entomophthorales: entomophthoraceae).	hydrophobic and hydrophilic kaolin-based particle films are effective for control of insect pests in certain agricultural crops. how these products interact with potential biological control agents is not well documented. this study was conducted to evaluate the effects of the hydrophobic (m96-018) and hydrophilic (surround wp) kaolin-based particle films (engelhard corporation, iselin, nj) on pea aphid, acyrthosiphon pisum (harris), on peas (pisum spp.), and on the fungal aphid pathogen pandora ...	2006	16573319
sweet problems: insect traits defining the limits to dietary sugar utilisation by the pea aphid, acyrthosiphon pisum.	plant phloem sap is an extreme diet for animals, partly because of its high and variable sugar content. the physiological and feeding traits of the pea aphid acyrthosiphon pisum that define the upper and lower limits to the range of dietary sucrose concentrations utilised by this insect were determined principally using chemically defined diets containing 0.125-1.5 mol l(-1) sucrose. on the diets with 0.125 mol l(-1) and 1.5 mol l(-1) sucrose, the aphids died as larvae within 8 and 14 days of bi ...	2006	16574799
ecological specialization correlates with genotypic differentiation in sympatric host-populations of the pea aphid.	the pea aphid, acyrthosiphon pisum, encompasses distinct host races specialized on various fabaceae species, but the extent of genetic divergence associated with ecological specialization varies greatly depending on plant and geographic origins of aphid populations. here, we studied the genetic structure of french sympatric pea aphid populations collected on perennial (pea and faba bean) and annual (alfalfa and red clover) hosts using 14 microsatellite loci. classical and bayesian population gen ...	2006	16599915
symbiont modifies host life-history traits that affect gene flow.	the evolution of herbivore-host plant specialization requires low levels of gene flow between populations on alternate plant species. accordingly, selection for host plant specialization is most effective when genotypes have minimal exposure to, and few mating opportunities with individuals from, alternate habitats. maternally transmitted bacterial symbionts are common in insect herbivores and can influence host fecundity under a variety of conditions. symbiont-mediated effects on host life-hist ...	2006	16600884
phylogeny of the sex-determining gene sex-lethal in insects.	the sex-lethal (sxl) protein belongs to the family of rna-binding proteins and is involved in the regulation of pre-mrna splicing. sxl has undergone an obvious change of function during the evolution of the insect clade. the gene has acquired a pivotal role in the sex-determining pathway of drosophila, although it does not act as a sex determiner in non-drosophilids. we collected sxl sequences of insect species ranging from the pea aphid (acyrtho siphom pisum) to drosophila melanogaster by searc ...	2006	16604108
functional genomics of buchnera and the ecology of aphid hosts.	in many animal groups, mutualistic bacterial symbionts play a central role in host ecology, by provisioning rare nutrients and thus enabling specialization on restricted diets. among such symbionts, genomic studies are most advanced for buchnera, the obligate symbiont of aphids, which feed on phloem sap. the contents of the highly reduced buchnera genomes have verified its role in aphid nutrition. comparisons of buchnera gene sets indicate ongoing, irreversible gene losses that are expected to a ...	2006	16626452
the effect of predators and hymenopterous parasites on population fluctuations of alfalfa aphids.	among alfalfa pests in iran three aphid species, green alfalfa aphid acyrthosiphon pisum harris spotted alfalfa aphid therioaphis trifolii forma maculata buckton and blue alfalfa aphid, acyrthosiphon kondoi shinji are important pests. the green alfalfa aphid can be observed all along the growing season particularly from late may to mid june at karaj climate conditions. during this period, the mean monthly maximum temperature and relative humidity were about 28 degrees c and 60-65% respectively. ...	2005	16628912
infectivity of nanovirus dnas: induction of disease by cloned genome components of faba bean necrotic yellows virus.	circumstantial evidence suggests that the genome of faba bean necrotic yellows virus (fbnyv), a nanovirus, consists of eight distinct, circular, single-stranded dnas, each of about 1 kb and encoding only one protein. here, the use of cloned full-length fbnyv dnas for reproducing fbnyv-like symptoms in vicia faba, the principal natural host of fbnyv, is reported. characteristic symptoms of fbnyv infection were obtained in faba bean plants following biolistic dna delivery or agroinoculation with a ...	2006	16690940
costs and benefits of a superinfection of facultative symbionts in aphids.	symbiotic associations between animals and inherited micro-organisms are widespread in nature. in many cases, hosts may be superinfected with multiple inherited symbionts. acyrthosiphon pisum (the pea aphid) may harbour more than one facultative symbiont (called secondary symbionts) in addition to the obligate primary symbiont, buchnera aphidicola. previously we demonstrated that, in a controlled genetic background, a. pisum infected with either serratia symbiotica or hamiltonella defensa (calle ...	2006	16720402
effect of low and high-saponin lines of alfalfa on pea aphid.	pea aphid fed on a high-saponin line of alfalfa showed reduction of reproduction and survival, and disturbance in development of its population. this line negatively influenced aphid probing behaviour, particularly prolonging the non-probing period and probing of the peripheral tissues (epidermis and mesophyll) and shortening the period of phloem sap ingestion. the high-saponin line of alfalfa differed from the low-saponin one by the presence of zanhic acid tridesmoside and a higher level of 3-g ...	2006	16740274
the pea aphid, acyrthosiphon pisum: an emerging genomic model system for ecological, developmental and evolutionary studies.	aphids display an abundance of adaptations that are not easily studied in existing model systems. here we review the biology of a new genomic model system, the pea aphid, acyrthosiphon pisum. we then discuss several phenomena that are particularly accessible to study in the pea aphid: the developmental genetic basis of polyphenisms, aphid-bacterial symbioses, the genetics of adaptation and mechanisms of virus transmission. the pea aphid can be maintained in the laboratory and natural populations ...	2006	16850403
learning by the parasitoid wasp, aphidius ervi (hymenoptera: braconidae), alters individual fixed preferences for pea aphid color morphs.	learning, defined as changes in behavior that occur due to past experience, has been well documented for nearly 20 species of hymenopterous parasitoids. few studies, however, have explored the influence of learning on population-level patterns of host use by parasitoids in field populations. our study explores learning in the parasitoid aphidius ervi haliday that attacks pea aphids, acyrthosiphon pisum (harris). we used a sequence of laboratory experiments to investigate whether there is a learn ...	2006	16858585
hundreds of flagellar basal bodies cover the cell surface of the endosymbiotic bacterium buchnera aphidicola sp. strain aps.	buchnera aphidicola is the endosymbiotic bacterium of the pea aphid. due to its small genome size, buchnera lacks many essential genes for autogenous life but obtains nutrients from the host. although the buchnera cell is nonmotile, it retains clusters of flagellar genes that lack the late genes necessary for motility, including the flagellin gene. in this study, we show that the flagellar genes are actually transcribed and translated and that the buchnera cell surface is covered with hundreds o ...	2006	16952945