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the stimuli evoking the aerial-righting posture of falling pea aphids.some wingless insects possess aerial righting reflexes, suggesting that adaptation for controlling body orientation while falling through air could have preceded flight. when threatened by natural enemies, wingless pea aphids (acyrthosiphon pisum) may drop off their host plant and assume a stereotypic posture that rotates them in midair to land on their feet. the sensory information triggering aphids to assume this posture has so far been unknown. we subjected aphids to a series of tests, isolat ...201425104755
widespread host-dependent hybrid unfitness in the pea aphid species complex.linking adaptive divergence to hybrid unfitness is necessary to understand the ecological factors contributing to reproductive isolation and speciation. to date, this link has been demonstrated in few model systems, most of which encompass ecotypes that occupy relatively early stages in the speciation process. here we extend these studies by assessing how host-plant adaptation conditions hybrid fitness in the pea aphid, acyrthosiphon pisum. we made crosses between and within five pea aphid bioty ...201424957707
genomic regions repeatedly involved in divergence among plant-specialized pea aphid biotypes.understanding the genetic bases of biological diversification is a long-standing goal in evolutionary biology. here, we investigate whether replicated cases of adaptive divergence involve the same genomic regions in the pea aphid, acyrthosiphon pisum, a large complex of genetically differentiated biotypes, each specialized on different species of legumes. a previous study identified genomic regions putatively involved in host-plant adaptation and/or reproductive isolation by performing a hierarc ...201424953130
identification and comparative analysis of g protein-coupled receptors in pediculus humanus humanus.the body louse has the smallest genome size among the known genome-sequenced insects. here, 81 gpcrs were identified in pediculus humanus humanus, 56, 14, 6 and 5 gpcrs for family-a, -b, -c and -d, respectively. these gpcrs constitute the comparable repertoire of gpcrs with other insects. moreover, it contains a more complete set of neuropeptide and protein hormone receptors not even than acyrthosiphon pisum but also drosophila melanogaster, for example, sulfakinin, corazonin, trissin and pthrl ...201424952173
aphid-encoded variability in susceptibility to a parasitoid.many animals exhibit variation in resistance to specific natural enemies. such variation may be encoded in their genomes or derived from infection with protective symbionts. the pea aphid, acyrthosiphon pisum, for example, exhibits tremendous variation in susceptibility to a common natural enemy, the parasitic wasp aphidius ervi. pea aphids are often infected with the heritable bacterial symbiont, hamiltonella defensa, which confers partial to complete resistance against this parasitoid dependin ...201424916045
synthesis and biological activity of fluorescent neonicotinoid insecticide thiamethoxam.here, we describe the synthesis of two new fluorescent derivatives of thiamethoxam and compared their toxicity on aphid acyrthosiphon pisum and their mode of action on insect nicotinic acetylcholine receptors expressed on the sixth abdominal ganglion. the compound 3 with two 2-chlorothiazole moieties was found to be more toxic using toxicological bioassays 24 h and 48 h after exposure while compound 4 appeared more active using cockroach ganglionic depolarization. interestingly, thiamethoxam app ...201424915877
new insight into the rna interference response against cathepsin-l gene in the pea aphid, acyrthosiphon pisum: molting or gut phenotypes specifically induced by injection or feeding treatments.rna interference (rnai) has been widely and successfully used for gene inactivation in insects, including aphids, where dsrna administration can be performed either by feeding or microinjection. however, several aspects related to the aphid response to rnai, as well as the influence of the administration method on tissue response, or the mixed success to observe phenotypes specific to the gene targeted, are still unclear in this insect group. in the present study, we made the first direct compar ...201424859468
posterior localization of apvas1 positions the preformed germ plasm in the sexual oviparous pea aphid acyrthosiphon pisum.germline specification in some animals is driven by the maternally inherited germ plasm during early embryogenesis (inheritance mode), whereas in others it is induced by signals from neighboring cells in mid or late development (induction mode). in the metazoa, the induction mode appears as a more prevalent and ancestral condition; the inheritance mode is therefore derived. however, regarding germline specification in organisms with asexual and sexual reproduction it has not been clear whether b ...201424855557
reliable protocols for whole-mount fluorescent in situ hybridization (fish) in the pea aphid acyrthosiphon pisum: a comprehensive survey and analysis.rna in situ hybridization (ish), including chromogenic ish (cish) and fluorescent ish (fish), has become a powerful tool for revealing the spatial distribution of gene transcripts in model organisms. previously, we developed a robust protocol for whole-mount rna cish in the pea aphid acyrthosiphon pisum, an emerging insect genomic model. in order to improve the resolving capacity of gene detection, we comprehensively surveyed current protocols of whole-mount rna-fish and developed protocols that ...201424850784
neonicotinoid binding, toxicity and expression of nicotinic acetylcholine receptor subunits in the aphid acyrthosiphon pisum.neonicotinoid insecticides act on nicotinic acetylcholine receptor and are particularly effective against sucking pests. they are widely used in crops protection to fight against aphids, which cause severe damage. in the present study we evaluated the susceptibility of the pea aphid acyrthosiphon pisum to the commonly used neonicotinoid insecticides imidacloprid (imi), thiamethoxam (tmx) and clothianidin (clt). binding studies on aphid membrane preparations revealed the existence of high and low ...201424801634
comparison of the wing polyphenic response of pea aphids (acyrthosiphon pisum) to crowding and predator cues.1. pea aphids (acyrthosiphon pisum harris; hemiptera: aphididae) exhibit transgenerational wing polyphenism, in which unwinged females produce genetically identical winged offspring in response to environmental cues such as overcrowding and predation risk that indicate poor habitat quality. 2. laboratory experiments were carried out to explore the intensity of the wing polyphenic response of pea aphids exposed to cues from ladybird predators and crowding, and their response was compared to pea a ...201424791058
accelerated evolution of morph-biased genes in pea aphids.phenotypic plasticity, the production of alternative phenotypes (or morphs) from the same genotype due to environmental factors, results in some genes being expressed in a morph-biased manner. theoretically, these morph-biased genes experience relaxed selection, the consequence of which is the buildup of slightly deleterious mutations at these genes. over time, this is expected to result in increased protein divergence at these genes between species and a signature of relaxed purifying selection ...201424770714
characterization of an aphid-specific, cysteine-rich protein enriched in salivary glands.aphids secrete saliva into the phloem during their infestation of plants. previous studies have identified numerous saliva proteins, but little is known about the characteristics (physical and chemical) and functions of these proteins in aphid-plant interactions. this study characterized an unknown protein (acypi39568) that was predicted to be enriched in the salivary glands of pea aphid. this protein belongs to an aphid-specific, cysteine-rich protein family that contains 14 conserved cysteines ...201424731868
elevated co2 alters the feeding behaviour of the pea aphid by modifying the physical and chemical resistance of medicago truncatula.elevated co(2) compromises the resistance of leguminous plants against chewing insects, but little is known about whether elevated co(2) modifies the resistance against phloem-sucking insects or whether it has contrasting effects on the resistance of legumes that differ in biological nitrogen fixation. we tested the hypothesis that the physical and chemical resistance against aphids would be increased in jemalong (a wild type of medicago truncatula) but would be decreased in dnf1 (a mutant witho ...201424697655
solenopsis invicta virus 3: mapping of structural proteins, ribosomal frameshifting, and similarities to acyrthosiphon pisum virus and kelp fly virus.solenopsis invicta virus 3 (sinv-3) is a positive-sense single-stranded rna virus that infects the red imported fire ant, solenopsis invicta. we show that the second open reading frame (orf) of the dicistronic genome is expressed via a frameshifting mechanism and that the sequences encoding the structural proteins map to both orf2 and the 3' end of orf1, downstream of the sequence that encodes the rna-dependent rna polymerase. the genome organization and structural protein expression strategy re ...201424686475
species interactions and a chain of indirect effects driven by reduced precipitation.climate change can affect species directly and indirectly by altering interactions between species within communities. these indirect effects can ramify through a community and affect many species, including some that may not have been directly affected by the perturbation. identifying these chains of indirect effects is difficult, and most studies only follow indirect effects across two or three species. here, we use a factorial field experiment to demonstrate that precipitation affects spotted ...201424669741
orysata, a jacalin-related lectin from rice, could protect plants against biting-chewing and piercing-sucking insects.the present study reports the insecticidal activity of orysata, a lectin from rice with mannose specificity, belonging to the family of jacalin-related lectins. the effect of orysata was investigated against three important pest insects in agriculture: the beet armyworm spodoptera exigua hübner (lepidoptera: noctuidae), and two aphid pests: green peach aphid myzus persicae sulzer and pea aphid acyrthosiphon pisum (hemiptera: aphidoidea). bioassays with s. exigua and m. persicae were performed us ...201424656332
differential induction of pisum sativum defense signaling molecules in response to pea aphid infestation.this study demonstrates the sequence of enhanced generation of signal molecules such as phytohormones, i.e. jasmonic acid (ja), ethylene (et), salicylic acid (sa), and a relatively stable free radical, nitric oxide (no), in response of pisum sativum l. cv. cysterski seedling leaves to the infestation of pea aphid acyrthosiphon pisum (harris) at a varied population size. in time from 0 to 96h after a. pisum infestation these signal molecules accumulated transiently. moreover, the convergence of t ...201424656330
delayed virulence and limited costs promote fecundity compensation upon infection.individuals invest limited resources across vital tasks such as reproduction and survival. individuals can spread reproductive investment over their lifetime, but cues of death or reduced fitness can influence this investment. in some systems, cues of infection induce early but costly reproduction through fecundity compensation as future reproduction becomes uncertain. a key aspect of parasite biology is the delay between exposure to parasites and the onset of virulence. this creates an importan ...201424642493
gene expression analysis of parthenogenetic embryonic development of the pea aphid, acyrthosiphon pisum, suggests that aphid parthenogenesis evolved from meiotic oogenesis.aphids exhibit a form of phenotypic plasticity, called polyphenism, in which genetically identical females reproduce sexually during one part of the life cycle and asexually (via parthenogenesis) during the remainder of the life cycle. the molecular basis for aphid parthenogenesis is unknown. cytological observations of aphid parthenogenesis suggest that asexual oogenesis evolved either through a modification of meiosis or from a mitotic process. as a test of these alternatives, we assessed the ...201425501006
genetic control of contagious asexuality in the pea aphid.although evolutionary transitions from sexual to asexual reproduction are frequent in eukaryotes, the genetic bases of such shifts toward asexuality remain largely unknown. we addressed this issue in an aphid species where both sexual and obligate asexual lineages coexist in natural populations. these sexual and asexual lineages may occasionally interbreed because some asexual lineages maintain a residual production of males potentially able to mate with the females produced by sexual lineages. ...201425473828
selection of reference genes for expression analysis using quantitative real-time pcr in the pea aphid, acyrthosiphon pisum (harris) (hemiptera, aphidiae).to facilitate gene expression study and obtain accurate qrt-pcr analysis, normalization relative to stable expressed housekeeping genes is required. in this study, expression profiles of 11 candidate reference genes, including actin (actin), elongation factor 1 α (ef1a), tata-box-binding protein (tata), ribosomal protein l12 (rpl12), β-tubulin (tubulin), nadh dehydrogenase (nadh), vacuolar-type h+-atpase (v-atpase), succinate dehydrogenase b (sdhb), 28s ribosomal rna (28s), 16s ribosomal rna (16 ...201425423476
a recombinant fusion protein containing a spider toxin specific for the insect voltage-gated sodium ion channel shows oral toxicity towards insects of different orders.recombinant fusion protein technology allows specific insecticidal protein and peptide toxins to display activity in orally-delivered biopesticides. the spider venom peptide δ-amaurobitoxin-pi1a, which targets insect voltage-gated sodium channels, was fused to the "carrier" snowdrop lectin (gna) to confer oral toxicity. the toxin itself (pi1a) and an amaurobitoxin/gna fusion protein (pi1a/gna) were produced using the yeast pichia pastoris as expression host. although both proteins caused mortali ...201424486516
aphid polyphenisms: trans-generational developmental regulation through viviparity.polyphenism, in which multiple discrete phenotypes develop from a single genotype, is considered to have contributed to the evolutionary success of aphids. of the various polyphenisms observed in the complex life cycle of aphids, the reproductive and wing polyphenisms seen in most aphid species are conspicuous. in reproductive polyphenism, the reproductive modes can change between viviparous parthenogenesis and sexual reproduction in response to the photoperiod. under short-day conditions in aut ...201424478714
genetic variation in resistance and fecundity tolerance in a natural host-pathogen interaction.individuals vary in their ability to defend against pathogens. determining how natural selection maintains this variation is often difficult, in part because there are multiple ways that organisms defend themselves against pathogens. one important distinction is between mechanisms of resistance that fight off infection, and mechanisms of tolerance that limit the impact of infection on host fitness without influencing pathogen growth. theory predicts variation among genotypes in resistance, but n ...201424689981
effects of a protease inhibitor protein from xenorhabdus bovienii on physiology of pea aphid (acyrthosiphon pisum).the effects of a protease inhibitor protein from xenorhabdus bovienii strain xbi1 (xbpi-1) on biochemistry and physiology of pea aphid (acyrthosiphon pisum) were studied, and the effects of xbpi-1 on the activities of aphid aminopeptidase and the concentrations of carbohydrates, free amino acids and lipids in a. pisum were determined. the results showed that the activity of aminopeptidase was reduced 18.30% by xbpi-1 in vitro assays. in addition, the total sugar, glycogen, and lipid concentratio ...201424485320
inheritance patterns of secondary symbionts during sexual reproduction of pea aphid biotypes.herbivorous insects frequently harbor bacterial symbionts that affect their ecology and evolution. aphids host the obligatory endosymbiont buchnera, which is required for reproduction, together with facultative symbionts whose frequencies vary across aphid populations. these maternally transmitted secondary symbionts have been particularly studied in the pea aphid, acyrthosiphon pisum, which harbors at least 8 distinct bacterial species (not counting buchnera) having environmentally dependent ef ...201424382700
a substrate ambiguous enzyme facilitates genome reduction in an intracellular symbiont.genome evolution in intracellular microbial symbionts is characterized by gene loss, generating some of the smallest and most gene-poor genomes known. as a result of gene loss these genomes commonly contain metabolic pathways that are fragmented relative to their free-living relatives. the evolutionary retention of fragmented metabolic pathways in the gene-poor genomes of endosymbionts suggests that they are functional. however, it is not always clear how they maintain functionality. to date, th ...201425527092
comparative transcriptomic analyses revealed divergences of two agriculturally important aphid species.grain aphid (sitobion avenae f) and pea aphid (acyrthosiphon pisum) are two agriculturally important pest species, which cause significant yield losses to crop plants each year by inflicting damage both through the direct effects of feeding and by vectoring debilitating plant viruses. although a close phylogenetic relationship between grain aphid and pea aphid was proposed, the biological variations between these two aphid species are obvious. while the host ranges of grain aphid is restricted t ...201425424897
adenine methylation may contribute to endosymbiont selection in a clonal aphid population.the pea aphid acyrthosiphon pisum has two modes of reproduction: parthenogenetic during the spring and summer and sexual in autumn. this ability to alternate between reproductive modes and the emergence of clonal populations under favorable conditions make this organism an interesting model for genetic and epigenetic studies. the pea aphid hosts different types of endosymbiotic bacteria within bacteriocytes which help the aphids survive and adapt to new environmental conditions and habitats. the ...201425406741
whole-genome re-sequencing of non-model organisms: lessons from unmapped reads.unmapped reads are often discarded from the analysis of whole-genome re-sequencing, but new biological information and insights can be uncovered through their analysis. in this paper, we investigate unmapped reads from the re-sequencing data of 33 pea aphid genomes from individuals specialized on different host plants. the unmapped reads for each individual were retrieved following mapping to the acyrthosiphon pisum reference genome and its mitochondrial and symbiont genomes. these sets of unmap ...201425269379
matching the supply of bacterial nutrients to the nutritional demand of the animal host.various animals derive nutrients from symbiotic microorganisms with much-reduced genomes, but it is unknown whether, and how, the supply of these nutrients is regulated. here, we demonstrate that the production of essential amino acids (eaas) by the bacterium buchnera aphidicola in the pea aphid acyrthosiphon pisum is elevated when aphids are reared on diets from which that eaa are omitted, demonstrating that buchnera scale eaa production to host demand. quantitative proteomics of bacteriocytes ...201425080346
diversification of mif immune regulators in aphids: link with agonistic and antagonistic interactions.the widespread use of genome sequencing provided evidences for the high degree of conservation in innate immunity signalling pathways across animal phyla. however, the functioning and evolutionary history of immune-related genes remains unknown for most invertebrate species. a striking observation coming from the analysis of the pea aphid acyrthosiphon pisum genome is the absence of important conserved genes known to be involved in the antimicrobial responses of other insects. this reduction in ...201425193628
factors limiting the spread of the protective symbiont hamiltonella defensa in aphis craccivora aphids.many insects are associated with heritable symbionts that mediate ecological interactions, including host protection against natural enemies. the cowpea aphid, aphis craccivora, is a polyphagous pest that harbors hamiltonella defensa, which defends against parasitic wasps. despite this protective benefit, this symbiont occurs only at intermediate frequencies in field populations. to identify factors constraining h. defensa invasion in ap. craccivora, we estimated symbiont transmission rates, per ...201425015890
settling down: the genome of serratia symbiotica from the aphid cinara tujafilina zooms in on the process of accommodation to a cooperative intracellular life.particularly interesting cases of mutualistic endosymbioses come from the establishment of co-obligate associations of more than one species of endosymbiotic bacteria. throughout symbiotic accommodation from a free-living bacterium, passing through a facultative stage and ending as an obligate intracellular one, the symbiont experiences massive genomic losses and phenotypic adjustments. here, we scrutinized the changes in the coevolution of serratia symbiotica and buchnera aphidicola endosymbion ...201424951564
an ecological cost associated with protective symbionts of aphids.beneficial symbioses are widespread and diverse in the functions they provide to the host ranging from nutrition to protection. however, these partnerships with symbionts can be costly for the host. such costs, so called "direct costs", arise from a trade-off between allocating resources to symbiosis and other functions such as reproduction or growth. ecological costs may also exist when symbiosis negatively affects the interactions between the host and other organisms in the environment. althou ...201424683464
aphid facultative symbionts reduce survival of the predatory lady beetle hippodamia convergens.non-essential facultative endosymbionts can provide their hosts with protection from parasites, pathogens, and predators. for example, two facultative bacterial symbionts of the pea aphid (acyrthosiphon pisum), serratia symbiotica and hamiltonella defensa, protect their hosts from parasitism by two species of parasitoid wasp. previous studies have not explored whether facultative symbionts also play a defensive role against predation in this system. we tested whether feeding on aphids harboring ...201424555501
exposure to natural pathogens reveals costly aphid response to fungi but not bacteria.immune responses are costly, causing trade-offs between defense and other host life history traits. aphids present a special system to explore the costs associated with immune activation since they are missing several humoral and cellular mechanisms thought important for microbial resistance, and it is unknown whether they have alternative, novel immune responses to deal with microbial threat. here we expose pea aphids to an array of heat-killed natural pathogens, which should stimulate immune r ...201424634732
phenotypic effect of "candidatus rickettsiella viridis," a facultative symbiont of the pea aphid (acyrthosiphon pisum), and its interaction with a coexisting symbiont.a gammaproteobacterial facultative symbiont of the genus rickettsiella was recently identified in the pea aphid, acyrthosiphon pisum. infection with this symbiont altered the color of the aphid body from red to green, potentially affecting the host's ecological characteristics, such as attractiveness to different natural enemies. in european populations of a. pisum, the majority of rickettsiella-infected aphids also harbor another facultative symbiont, of the genus hamiltonella. we investigated ...201424212575
the combined effects of bacterial symbionts and aging on life history traits in the pea aphid, acyrthosiphon pisum.while many endosymbionts have beneficial effects on hosts under specific ecological conditions, there can also be associated costs. in order to maximize their own fitness, hosts must facilitate symbiont persistence while preventing symbiont exploitation of resources, which may require tight regulation of symbiont populations. as a host ages, the ability to invest in such mechanisms may lessen or be traded off with demands of other life history traits, such as survival and reproduction. using the ...201424185857
stem nematode counteracts plant resistance of aphids in alfalfa, medicago sativa.plants are exploited by a diverse community of insect herbivores and phytopathogens that interact indirectly through plant-mediated interactions. generally, plants are thought to respond to insects and pathogens through different defensive signaling pathways. as plants are selected for resistance to one phytophagous organism type (insect vs. pathogen) in managed systems, it is not clear how this selection may affect community interactions. this study examined the effect of nematode-resistant var ...201425261892
natural occurrence of entomophthoroid fungi of aphid pests on medicago sativa l. in argentina.four species of entomophthoroid fungi, pandora neoaphidis (entomophthorales: entomophthoraceae), zoophthora radicans (entomophthorales: entomophthoraceae), entomophthora planchoniana (entomophthorales: entomophthoraceae) and neozygites fresenii (neozygitales: neozygitaceae) were found to infect aphis craccivora, therioaphis trifolii, and acyrthosiphon pisum and unidentified species of acyrthosiphon on lucerne in argentina. samples were collected from five sites (ceres, rafaela, sarmiento, monte ...201424721275
genome-wide annotation and functional identification of aphid glut-like sugar transporters.phloem feeding insects, such as aphids, feed almost continuously on plant phloem sap, a liquid diet that contains high concentrations of sucrose (a disaccharide comprising of glucose and fructose). to access the available carbon, aphids hydrolyze sucrose in the gut lumen and transport its constituent monosaccharides, glucose and fructose. although sugar transport plays a critical role in aphid nutrition, the molecular basis of sugar transport in aphids, and more generally across all insects, rem ...201425091229
isolation and identification of culturable bacteria from honeydew of whitefly, bemisia tabaci (g.) (hemiptera: aleyrodidae).bemisia tabaci (g.) is an important pest and a vector of gemini viruses infecting plants. during the process of feeding b. tabaci excretes honeydew which is rich in nutrients, and an excellent medium for microbial growth. recent report proved that volatile emitted by the honeydew associated bacteria of aphid, acyrthosiphon pisum harris was involved in natural enemy calling. thus understanding the honeydew associated bacteria is of paramount importance from the non-chemical method of insect pest ...201425606395
molecular characterization of the aphis gossypii olfactory receptor gene families.the cotton aphid, aphis gossypii glover, is a polyphagous pest that inflicts great damage to cotton yields worldwide. antennal olfaction, which is extremely important for insect survival, mediates key behaviors such as host preference, mate choice, and oviposition site selection. in insects, odor detection is mediated by odorant receptors (ors) and ionotropic receptors (irs), which ensure the specificity of the olfactory sensory neuron responses. in this study, our aim is to identify chemosensor ...201424971460
identification of the main venom protein components of aphidius ervi, a parasitoid wasp of the aphid model acyrthosiphon pisum.endoparasitoid wasps are important natural enemies of the widely distributed aphid pests and are mainly used as biological control agents. however, despite the increased interest on aphid interaction networks, only sparse information is available on the factors used by parasitoids to modulate the aphid physiology. our aim was here to identify the major protein components of the venom injected at oviposition by aphidius ervi to ensure successful development in its aphid host, acyrthosiphon pisum.201424884493
angiotensin-converting enzymes modulate aphid-plant interactions.angiotensin-converting enzymes (aces) are key components of the renin-angiotensin system in mammals. however, the function of ace homologs in insect saliva is unclear. aphids presumably deliver effector proteins via saliva into plant cells to maintain a compatible insect-plant interaction. in this study, we showed that ace modulates aphid-plant interactions by affecting feeding behavior and survival of aphids on host plants. three ace genes were identified from the pea aphid acyrthosiphon pisum ...201525744345
up-regulation of abscisic acid signaling pathway facilitates aphid xylem absorption and osmoregulation under drought stress.the activation of the abscisic acid (aba) signaling pathway reduces water loss from plants challenged by drought stress. the effect of drought-induced aba signaling on the defense and nutrition allocation of plants is largely unknown. we postulated that these changes can affect herbivorous insects. we studied the effects of drought on different feeding stages of pea aphids in the wild-type a17 of medicago truncatula and aba signaling pathway mutant sta-1. we examined the impact of drought on pla ...201526546578
drawing the line.the pea aphid acyrthosiphon pisum is an agriculturally important pest of leguminous plants including peas and broad beans. the widespread use of chemical pesticides impacts heavily on the environment, and increases pesticide-resistant pea aphid populations, so alternative strategies are being actively sought. pseudomonas syringae bacteria are known to infect and kill the pea aphid, and offer a possible control strategy. in this study, the authors measured the effects of injecting p. syringae on ...201526438421
house fly (musca domestica l.) attraction to insect honeydew.house flies are of major concern as vectors of food-borne pathogens to food crops. house flies are common pests on cattle feedlots and dairies, where they develop in and feed on animal waste. by contacting animal waste, house flies can acquire human pathogenic bacteria such as escherichia coli and salmonella spp., in addition to other bacteria, viruses, or parasites that may infect humans and animals. the subsequent dispersal of house flies from animal facilities to nearby agricultural fields co ...201525970333
new cyt-like δ-endotoxins from dickeya dadantii: structure and aphicidal activity.in the track of new biopesticides, four genes namely cyta, cytb, cytc and cytd encoding proteins homologous to bacillus thuringiensis (bt) cyt toxins have been identified in the plant pathogenic bacteria dickeya dadantii genome. here we show that three cyt-like δ-endotoxins from d. dadantii (cyta, cytb and cytc) are toxic to the pathogen of the pea aphid acyrthosiphon pisum in terms of both mortality and growth rate. the phylogenetic analysis of the comprehensive set of cyt toxins available in g ...201525740111
peroxiredoxin 1 protects the pea aphid acyrthosiphon pisum from oxidative stress induced by micrococcus luteus infection.reactive oxygen species (ross) are generated in organisms in response to infections caused by invading microbes. however, excessive ross will inflict oxidative damage on the host. peroxiredoxins (prxs) are antioxidative enzymes that may eliminate ross efficiently. in this study, apprx1 from the pea aphid acyrthosiphon pisum was cloned, and its function was investigated in vitro and in vivo. in the presence of dtt, recombinant apprx1 protein from escherichia coli showed antioxidative activity by ...201525817695
conditional reduction of predation risk associated with a facultative symbiont in an insect.symbionts are widespread among eukaryotes and their impacts on the ecology and evolution of their hosts are meaningful. most insects harbour obligate and facultative symbiotic bacteria that can influence their phenotype. in the pea aphid acyrthosiphon pisum, an astounding symbiotic-mediated phenotype has been recently observed: when infected with the symbiotic bacteria rickettsiella viridis, young red aphid larvae become greener at adulthood and even darker green when co-infected with rickettsie ...201526618776
a facultative endosymbiont in aphids can provide diverse ecological benefits.ecologically important traits of insects are often affected by facultative bacterial endosymbionts. this is best studied in the pea aphid acyrthosiphon pisum, which is frequently infected by one or more of eight facultative symbiont species. many of these symbiont species have been shown to provide one ecological benefit, but we have little understanding of the range of effects that a single strain can have. here, we describe the phenotypes conferred by three strains of the recently discovered b ...201526206380
evidence for specificity in symbiont-conferred protection against parasitoids.many insects harbour facultative symbiotic bacteria, some of which have been shown to provide resistance against natural enemies. one of the best-known protective symbionts is hamiltonella defensa, which in pea aphid (acyrthosiphon pisum) confers resistance against attack by parasitoid wasps in the genus aphidius (braconidae).we asked (i) whether this symbiont also confers protection against a phylogenetically distant group of parasitoids (aphelinidae) and (ii) whether there are consistent diffe ...201526136451
the genome of diuraphis noxia, a global aphid pest of small grains.the russian wheat aphid, diuraphis noxia kurdjumov, is one of the most important pests of small grains throughout the temperate regions of the world. this phytotoxic aphid causes severe systemic damage symptoms in wheat, barley, and other small grains as a direct result of the salivary proteins it injects into the plant while feeding.201526044338
infection dynamic of symbiotic bacteria in the pea aphid acyrthosiphon pisum gut and host immune response at the early steps in the infection process.in addition to its obligatory symbiont buchnera aphidicola, the pea aphid acyrthosiphon pisum can harbor several facultative bacterial symbionts which can be mutualistic in the context of various ecological interactions. belonging to a genus where many members have been described as pathogen in invertebrates, serratia symbiotica is one of the most common facultative partners found in aphids. the recent discovery of strains able to grow outside their host allowed us to simulate environmental acqu ...201525811863
bacterial communities associated with host-adapted populations of pea aphids revealed by deep sequencing of 16s ribosomal dna.associations between microbes and animals are ubiquitous and hosts may benefit from harbouring microbial communities through improved resource exploitation or resistance to environmental stress. the pea aphid, acyrthosiphon pisum, is the host of heritable bacterial symbionts, including the obligate endosymbiont buchnera aphidicola and several facultative symbionts. while obligate symbionts supply aphids with key nutrients, facultative symbionts influence their hosts in many ways such as protecti ...201525807173
experimental replacement of an obligate insect symbiont.symbiosis, the close association of unrelated organisms, has been pivotal in biological diversification. in the obligate symbioses found in many insect hosts, organisms that were once independent are permanently and intimately associated, resulting in expanded ecological capabilities. the primary model for this kind of symbiosis is the association between the bacterium buchnera and the pea aphid (acyrthosiphon pisum). a longstanding obstacle to efforts to illuminate genetic changes underlying ob ...201525561531
automated solution-phase synthesis of insect glycans to probe the binding affinity of pea enation mosaic virus.pea enation mosaic virus (pemv)--a plant rna virus transmitted exclusively by aphids--causes disease in multiple food crops. however, the aphid-virus interactions required for disease transmission are poorly understood. for virus transmission, pemv binds to a heavily glycosylated receptor aminopeptidase n in the pea aphid gut and is transcytosed across the gut epithelium into the aphid body cavity prior to release in saliva as the aphid feeds. to investigate the role of glycans in pemv-aphid int ...201526457763
in vitro evidence supports membrane alanyl aminopeptidase n as a receptor for a plant virus in the pea aphid vector.insect-borne plant viruses cause significant agricultural losses and jeopardize sustainable global food production. although blocking plant virus transmission would allow for crop protection, virus receptors in insect vectors are unknown. here we identify membrane alanyl aminopeptidase n (apn) as a receptor for pea enation mosaic virus (pemv) coat protein (cp) in the gut of the pea aphid, acyrthosiphon pisum, using a far-western blot method. pulldown and immunofluorescence binding assays and sur ...201526311872
horizontal transfer of facultative endosymbionts is limited by host relatedness.heritable microbial symbionts can have important effects on many aspects of their hosts' biology. acquisition of a novel symbiont strain can provide fitness benefits to the host, with significant ecological and evolutionary consequences. we measured barriers to horizontal transmission by artificially transferring facultative symbionts from the grain aphid, sitobion avenae, and five other aphid species into two clonal genotypes of s. avenae. we found the symbiont hamiltonella defensa establishes ...201526332792
patterns, causes and consequences of defensive microbiome dynamics across multiple scales.the microbiome can significantly impact host phenotypes and serve as an additional source of heritable genetic variation. while patterns across eukaryotes are consistent with a role for symbiotic microbes in host macroevolution, few studies have examined symbiont-driven host evolution or the ecological implications of a dynamic microbiome across temporal, spatial or ecological scales. the pea aphid, acyrthosiphon pisum, and its eight heritable bacterial endosymbionts have served as a model for s ...201525683348
do bacterial symbionts govern aphid's dropping behavior?defensive symbiosis is amongst nature's most important interactions shaping the ecology and evolution of all partners involved. the pea aphid, acyrthosiphon pisum harris (hemiptera: aphididae), harbors one obligatory bacterial symbiont and up to seven different facultative symbionts, some of which are known to protect the aphid from pathogens, natural enemies, and other mortality factors. pea aphids typically drop off the plant when a mammalian herbivore approaches it to avoid incidental predati ...201526313964
proton-dependent glutamine uptake by aphid bacteriocyte amino acid transporter apglnt1.aphids house large populations of the gammaproteobacterial symbiont buchnera aphidicola in specialized bacteriocyte cells. the combined biosynthetic capability of the holobiont (acyrthosiphon pisum and buchnera) is sufficient for biosynthesis of all twenty protein coding amino acids, including amino acids that animals alone cannot synthesize; and that are present at low concentrations in a. pisum's plant phloem sap diet. collaborative holobiont amino acid biosynthesis depends on glutamine import ...201526028424
detection and decay rates of prey and prey symbionts in the gut of a predator through metagenomics.dna methods are useful to identify ingested prey items from the gut of predators, but reliable detection is hampered by low amounts of degraded dna. pcr-based methods can retrieve minute amounts of starting material but suffer from amplification biases and cross-reactions with the predator and related species genomes. here, we use pcr-free direct shotgun sequencing of total dna isolated from the gut of the harlequin ladybird harmonia axyridis at five time points after feeding on a single pea aph ...201525545417
transcriptome analysis of sexually dimorphic chinese white wax scale insects reveals key differences in developmental programs and transcription factor expression.the chinese white wax scale insect, ericerus pela, represents one of the most dramatic examples of sexual dimorphism in any insect species. in this study, we showed that although e. pela males display complete metamorphosis similar to holometabolous insects, the species forms the sister group to acyrthosiphon pisum and cluster with hemimetabolous insects. the gene expression profile and gene ontology (go) analyses revealed that the two sexes engaged in distinct developmental programs. in particu ...201525634031
stable isotope studies reveal pathways for the incorporation of non-essential amino acids in acyrthosiphon pisum (pea aphids).plant roots incorporate inorganic nitrogen into the amino acids glutamine, glutamic acid, asparagine and aspartic acid, which together serve as the primary metabolites of nitrogen transport to other tissues. given the preponderance of these four amino acids, phloem sap is a nutritionally unbalanced diet for phloem-feeding insects. therefore, aphids and other phloem feeders typically rely on microbial symbionts for the synthesis of essential amino acids. to investigate the metabolism of the four ...201526632455
amino acid-mediated impacts of elevated carbon dioxide and simulated root herbivory on aphids are neutralized by increased air temperatures.changes in host plant quality, including foliar amino acid concentrations, resulting from global climate change and attack from multiple herbivores, have the potential to modify the pest status of insect herbivores. this study investigated how mechanically simulated root herbivory of lucerne (medicago sativa) before and after aphid infestation affected the pea aphid (acyrthosiphon pisum) under elevated temperature (et) and carbon dioxide concentrations (eco2). et increased plant height and bioma ...201525403916
expression of stress-related genes in the parthenogenetic forms of the pea aphid, acyrthosiphon pisum.aphids are an economically important group of insects that have an intricate life cycle with seasonal polyphenism. this study aimed to explore the physiological background of aphid migration from unfavorable nutritional conditions to a new, intact host plant. specifically, the relative expression of stress/metabolism-related genes and changes in metabolic reserves were determined for the winged and wingless forms of female pea aphids, acyrthosiphon pisum, under two different nutritional conditio ...201525461486
morphology and proteome characterization of the salivary glands of the western chinch bug (hemiptera: blissidae).the western chinch bug, blissus occiduus barber, is a serious pest of buffalograss, buchloe dactyloides (nuttall) due to physical and chemical damage caused during the feeding process. although previous work has investigated the feeding behaviors of chinch bugs in the blissus complex, no study to date has explored salivary gland morphology and the associated salivary complex of this insect. whole and sectioned b. occiduus salivary glands were visualized using light and scanning electron microsco ...201526470353
germ plasm localisation of the helicc of vasa in drosophila: analysis of domain sufficiency and amino acids critical for localisation.formation of the germ plasm drives germline specification in drosophila and some other insects such as aphids. identification of the dead-box protein vasa (vas) as a conserved germline marker in flies and aphids suggests that they share common components for assembling the germ plasm. however, to which extent the assembly order is conserved and the correlation between functions and sequences of vas remain unclear. ectopic expression of the pea aphid vas (apvas1) in drosophila did not drive its l ...201526419889
injection of insect membrane in xenopus oocyte: an original method for the pharmacological characterization of neonicotinoid insecticides.insect nicotinic acetylcholine receptors (nachrs) represent a major target of insecticides, belonging to the neonicotinoid family. however, the pharmacological profile of native nachrs is poorly documented, mainly because of a lack of knowledge of their subunit stoichiometry, their tissue distribution and the weak access to nachr-expressing cells. in addition, the expression of insect nachrs in heterologous systems remains hard to achieve. therefore, the structure-activity characterization of na ...201526391340
parasitic wasps aphidius ervi are more attracted to a blend of host-induced plant volatiles than to the independent compounds.arthropodal natural enemies respond to volatiles from plants infested by their prey/host herbivores (herbivore-induced plant volatiles; hipvs). however, the relative importance of hipv blends vs. each compound in the blend in attracting natural enemies is not fully understood. in this study, we investigated the response of a parasitic wasp, aphidius ervi, to hipvs that were specific or nonspecific to infestations by its host aphid, acyrthosiphon pisum. to select such compounds, we compared the v ...201526302986
host-associated differentiation in a highly polyphagous, sexually reproducing insect herbivore.insect herbivores may undergo genetic divergence on their host plants through host-associated differentiation (had). much of what we know about had involves insect species with narrow host ranges (i.e., specialists) that spend part or all their life cycle inside their hosts, and/or reproduce asexually (e.g., parthenogenetic insects), all of which are thought to facilitate had. however, sexually reproducing polyphagous insects can also exhibit had. few sexually reproducing insects have been teste ...201526257868
ants learn aphid species as mutualistic partners: is the learning behavior species-specific?in ant-aphid associations, many aphid species provide ants with honeydew and are tended by ants, whereas others are never tended and are frequently preyed upon by ants. in these relationships, ants must have the ability to discriminate among aphid species, with mutualistic aphids being accepted as partners rather than prey. although ants reportedly use cuticular hydrocarbons (chcs) of aphids to differentiate between mutualistic and non-mutualistic species, it is unclear whether the ability to re ...201526590597
the x chromosome of hemipteran insects: conservation, dosage compensation and sex-biased expression.insects of the order hemiptera (true bugs) use a wide range of mechanisms of sex determination, including genetic sex determination, paternal genome elimination, and haplodiploidy. genetic sex determination, the prevalent mode, is generally controlled by a pair of xy sex chromosomes or by an xx/x0 system, but different configurations that include additional sex chromosomes are also present. although this diversity of sex determining systems has been extensively studied at the cytogenetic level, ...201526556591
g protein coupled receptors as targets for next generation pesticides.there is an on-going need for the discovery and development of new pesticides due to the loss of existing products through the continuing development of resistance, the desire for products with more favourable environmental and toxicological profiles and the need to implement the principles of integrated pest management. insect g protein coupled receptors (gpcrs) have important roles in modulating biology, physiology and behaviour, including reproduction, osmoregulation, growth and development. ...201526226649
coping with shorter days: do phenology shifts constrain aphid fitness?climate change can alter the phenology of organisms. it may thus lead seasonal organisms to face different day lengths than in the past, and the fitness consequences of these changes are as yet unclear. to study such effects, we used the pea aphid acyrthosiphon pisum as a model organism, as it has obligately asexual clones which can be used to study day length effects without eliciting a seasonal response. we recorded life-history traits under short and long days, both with two realistic tempera ...201526207194
circulative nonpropagative aphid transmission of nanoviruses: an oversimplified view.plant virus species of the family nanoviridae have segmented genomes with the highest known number of segments encapsidated individually. they thus likely represent the most extreme case of the so-called multipartite, or multicomponent, viruses. all species of the family are believed to be transmitted in a circulative nonpropagative manner by aphid vectors, meaning that the virus simply crosses cellular barriers within the aphid body, from the gut to the salivary glands, without replicating or e ...201526178991
rna interference against gut osmoregulatory genes in phloem-feeding insects.in planta rnai (i.e. plants engineered to synthesize active rnai molecules) has great potential as a strategy to control insect crop pests. this study investigated the impact of rnai against osmoregulatory genes expressed in the gut of two phloem-feeding species, the green peach aphid myzus persicae and the potato/tomato psyllid bactericera cockerelli. the target genes comprising candidate gut sucrase, aquaporin and sugar transporter genes were identified by mining insect genomic and transcripto ...201526071792
feeding history affects intraguild interactions between harmonia axyridis (coleoptera: coccinellidae) and episyrphus balteatus (diptera: syrphidae).while the effect of several factors such as predator and prey size, morphology and developmental stage on intraguild predation (igp) is widely investigated, little is known about the influence of diet on the occurrence and outcome of igp. in the present study, the effect of the diet experienced during larval development on igp between the ladybird harmonia axyridis and the syrphid episyrphus balteatus is investigated. four diets were tested for h. axyridis: eggs of the mediterranean flour moth e ...201526030267
genome sequence of an alphabaculovirus isolated from the oak looper, lambdina fiscellaria, contains a putative 2-kilobase-pair transposable element encoding a transposase and a flywch domain-containing protein.the genome sequence of an alphabaculovirus isolated from lambdina fiscellaria indicated that it is a novel member of a group ii lineage. a putative transposable element was identified that contained two genes, including a transposase ortholog. these genes were most closely related to genes of the pea aphid, acyrthosiphon pisum.201526021909
the molecular correlates of organ loss: the case of insect malpighian tubules.malpighian tubules play an essential role in excretion, osmoregulation and immunity of most insects. exceptionally, aphids lack malpighian tubules, providing the opportunity to investigate the fate of genes expressed in an organ that has undergone evolutionary reduction and loss. making use of the sequenced genomes of drosophila melanogaster and the pea aphid acyrthosiphon pisum, we demonstrated that more than 50% of drosophila genes expressed specifically in the malpighian tubules had orthologu ...201525972400
molecular cloning and expression profile of an atp-binding cassette (abc) transporter gene from the hemipteran insect nilaparvata lugens.the atp-binding cassette (abc) transporters belong to a large superfamily of proteins that have important physiological functions in all living organisms. in insects, abc transporters have important functions in the transport of molecules, and are also involved in insecticide resistance, metabolism, and development. in this study, the nilaparvata lugens stal (hemiptera: delphacidae) abcg (nlabcg) gene was identified and characterized. the complete mrna sequence of nlabcg was 2608-bp long, with a ...201525867414
cascading effects of artificial light at night: resource-mediated control of herbivores in a grassland ecosystem.artificial light at night has a wide range of biological effects on both plants and animals. here, we review mechanisms by which artificial light at night may restructure ecological communities by modifying the interactions between species. such mechanisms may be top-down (predator, parasite or grazer controlled), bottom-up (resource-controlled) or involve non-trophic processes, such as pollination, seed dispersal or competition. we present results from an experiment investigating both top-down ...201525780243
does the aphid alarm pheromone (e)-β-farnesene act as a kairomone under field conditions?insect natural enemies use several environmental cues for host/prey finding, and adjust their foraging behavior according to these signals. in insects, such cues are mainly chemical, derived from the host plant or the prey itself. the aphid alarm pheromone, (e)-β-farnesene (ebf), is believed to be such a cue, because several aphid enemies are able to perceive ebf and show attractant behavior. these studies are, however, based mainly on electroantennogram or olfactometer assays, and often use unn ...201525779875
molecular features and toxicological properties of four common pesticides, acetamiprid, deltamethrin, chlorpyriphos and fipronil.structural features and selected physicochemical properties of four common pesticides: acetamiprid (neonicotinoid), chlorpyriphos (organophosphate insecticide), deltamethrin (pyrethroid) and fipronil (phenylpyrazole) have been investigated by density functional theory quantum chemical calculations. the high flexible character of these insecticides is revealed by the numerous conformers obtained, located within a 20kjmol(-1) range in the gas phase. in line with this trend, a redistribution of the ...201525716006
two host clades, two bacterial arsenals: evolution through gene losses in facultative endosymbionts.bacterial endosymbiosis is an important evolutionary process in insects, which can harbor both obligate and facultative symbionts. the evolution of these symbionts is driven by evolutionary convergence, and they exhibit among the tiniest genomes in prokaryotes. the large host spectrum of facultative symbionts and the high diversity of strategies they use to infect new hosts probably impact the evolution of their genome and explain why they undergo less severe genomic erosion than obligate symbio ...201525714744
armet is an effector protein mediating aphid-plant interactions.aphid saliva is predicted to contain proteins that modulate plant defenses and facilitate feeding. armet is a well-characterized bifunctional protein in mammalian systems. here we report a new role of armet, namely as an effector protein in the pea aphid, acyrthosiphon pisum. pea aphid armet's physical and chemical properties and its intracellular role are comparable to those reported for mammalian armets. uniquely, we detected armet in aphid watery saliva and in the phloem sap of fava beans fed ...201525678626
plant stomatal closure improves aphid feeding under elevated co2.stomata help plants regulate co2 absorption and water vapor release in response to various environmental changes, and plants decrease their stomatal apertures and enhance their water status under elevated co2 . although the bottom-up effect of elevated co2 on insect performance has been extensively studied, few reports have considered how insect fitness is altered by elevated co2 -induced changes in host plant water status. we tested the hypothesis that aphids induce stomatal closure and increas ...201525581722
aphid salivary proteases are capable of degrading sieve-tube proteins.sieve tubes serve as transport conduits for photo-assimilates and other resources in angiosperms and are profitable targets for piercing-sucking insects such as aphids. sieve-tube sap also contains significant amounts of proteins with diverse functions, for example in signalling, metabolism, and defence. the identification of salivary proteases in acyrthosiphon pisum led to the hypothesis that aphids might be able to digest these proteins and by doing so suppress plant defence and access additio ...201525540441
the structural sheath protein of aphids is required for phloem feeding.aphids produce two types of saliva that mediate their interactions with plants. watery saliva is secreted during cell penetration and ingestion, whereas gel saliva is secreted during stylet movement through the apoplast where it forms a sheath around the stylet to facilitate penetration and seal puncture sites on cell membranes. in order to study the function of the sheath when aphids interact with plants, we used rna interference (rnai) to silence the aphid structural sheath protein (shp) in th ...201525527379
cryptic virulence and avirulence alleles revealed by controlled sexual recombination in pea aphids.although aphids are worldwide crop pests, little is known about aphid effector genes underlying virulence and avirulence. here we show that controlling the genetics of both aphid and host can reveal novel recombinant genotypes with previously undetected allelic variation in both virulence and avirulence functions. clonal f1 progeny populations were derived from reciprocal crosses and self-matings between two parental genotypes of pea aphid (acyrthosiphon pisum) differing in virulence on a medica ...201525519896
the cytogenetic architecture of the aphid genome.in recent years aphids, with their well-defined polyphenism, have become favoured as model organisms for the study of epigenetic processes. the availability of the pea aphid (acyrthosiphon pisum) genome sequence has engendered much research aimed at elucidating the mechanisms by which the phenotypic plasticity of aphids is inherited and controlled. yet so far this research effort has paid little attention to the cytogenetic processes that play a vital part in the organisation, expression and inh ...201524593177
expression pattern analysis of odorant-binding proteins in the pea aphid acyrthosiphon pisum.odorant-binding proteins (obps) are soluble proteins mediating chemoreception in insects. in previous research, we investigated the molecular mechanisms adopted by aphids to detect the alarm pheromone (e)-β-farnesene and we found that the recognition of this and structurally related molecules is mediated by obp3 and obp7. here, we show the differential expression patterns of 5 selected obps (obp1, obp3, obp6, obp7, obp8) obtained performing quantitative rt-pcr and immunolocalization experiments ...201524591440
life-history trade-offs mediate 'personality' variation in two colour morphs of the pea aphid, acyrthosiphon pisum.life-history trade-offs are considered a major driving force in the emergence of consistent behavioural differences (personality variation); but empirical tests are scarce. we investigated links between a personality trait (escape response), life-history and state variables (growth rate, size and age at first reproduction, age-dependent reproductive rates, lifetime reproductive success, life span) in red and green colour morphs of clonal pea aphids, acyrthosiphon pisum. escape response (dropping ...201524942327
faba bean forisomes can function in defence against generalist aphids.phloem sieve elements have shut-off mechanisms that prevent loss of nutrient-rich phloem sap when the phloem is damaged. some phloem proteins such as the proteins that form forisomes in legume sieve elements are one such mechanism and in response to damage, they instantly form occlusions that stop the flow of sap. it has long been hypothesized that one function of phloem proteins is defence against phloem sap-feeding insects such as aphids. this study provides the first experimental evidence tha ...201525311512
dynamics of copy number variation in host races of the pea aphid.copy number variation (cnv) makes a major contribution to overall genetic variation and is suspected to play an important role in adaptation. however, aside from a few model species, the extent of cnv in natural populations has seldom been investigated. here, we report on cnv in the pea aphid acyrthosiphon pisum, a powerful system for studying the genetic architecture of host-plant adaptation and speciation thanks to multiple host races forming a continuum of genetic divergence. recent studies h ...201525234705
common genome-wide patterns of transcript accumulation underlying the wing polyphenism and polymorphism in the pea aphid (acyrthosiphon pisum).the pea aphid, acyrthosiphon pisum, exhibits several environmentally cued polyphenisms, in which discrete, alternative phenotypes are produced. at low-density, parthenogenetic females produce unwinged female progeny, but at high-density females produce progeny that develop with wings. these alternative phenotypes represent a solution to the competing demands of dispersal and reproduction. males also develop as either winged or unwinged, but these alternatives are determined by a genetic polymorp ...201517651358
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