| aphidbase: a centralized bioinformatic resource for annotation of the pea aphid genome. | aphidbase is a centralized bioinformatic resource that was developed to facilitate community annotation of the pea aphid genome by the international aphid genomics consortium (iagc). the aphidbase information system designed to organize and distribute genomic data and annotations for a large international community was constructed using open source software tools from the generic model organism database (gmod). the system includes apollo and gbrowse utilities as well as a wiki, blast search capa ... | 2010 | 20482635 |
| population differentiation and genetic variation in performance on eight hosts in the pea aphid complex. | phytophagous insects frequently use multiple host-plant species leading to the evolution of specialized host-adapted populations and sometimes eventually to speciation. some insects are confronted with a large number of host-plant species, which may provide complex routes of gene flow between host-adapted populations. the pea aphid (acyrthosiphon pisum) attacks a broad range of plants in the fabaceae and it is known that populations on trifolium pratense and medicago sativa can be highly special ... | 2008 | 18647340 |
| the pea aphid genome. | | 2010 | 20482634 |
| frass analysis of diets of aphidophagous lady beetles (coleoptera: coccinellidae) in utah alfalfa fields. | aphidophagous lady beetles enhance their foraging success in natural settings by consuming other types of food in addition to aphids. frass analysis was used to examine natural diets of female lady beetles in fields of alfalfa (medicago sativa l.) in northern utah. the first (spring) alfalfa crop was censused in 2004 and 2005 to determine the diet of female adults of the introduced coccinella septempunctata l., and two native species, c. transversoguttata richardsoni brown, and hippodamia conver ... | 2010 | 20388290 |
| the "acrostyle": a newly described anatomical structure in aphid stylets. | the recent demonstration that a plant virus could be retained on protein receptors located exclusively in a small area inside the common duct at the tip of aphid maxillary stylets indicated the possible existence of a distinct anatomical structure at this level. since no distinct feature within the common duct of any aphid species has ever been reported in the literature, we first carefully re-examined the distal extremity of the maxillary stylets of acyrthosiphon pisum using transmission- and s ... | 2010 | 20170746 |
| evaluation of the susceptibility of the pea aphid, acyrthosiphon pisum, to a selection of novel biorational insecticides using an artificial diet. | an improved technique was developed to assay the toxicity of insecticides against aphids using an artificial diet. the susceptibility of the pea aphid acyrthosiphon pisum (harris) (hemiptera: aphidoidea) was determined for a selection of novel biorational insecticides, each representing a novel mode of action. flonicamid, a novel systemic insecticide with selective activity as feeding blocker against sucking insects, showed high toxicity against first-instar a. pisum nymphs with an lc(50) of 20. ... | 2009 | 20053120 |
| cuticular proteins and seasonal photoperiodism in aphids. | for poikilotherm animals such as insects, extreme temperatures can be a severe issue in continental regions. aphids, which reproduce in spring and summer by viviparity, are prone to death in hard winter conditions. these species exhibit reproductive plasticity adapted to winter by producing oviparous females in autumn, which lay overwintering eggs. this switch is driven by photoperiodism, and long nights are sufficient to trigger the change in reproductive mode. global transcriptomic analyses ap ... | 2010 | 20018241 |
| design, multicomponent synthesis, and bioactivities of novel neonicotinoid analogues with 1,4-dihydropyridine scaffold. | novel neonicotinoid analogues bearing a 1,4-dihydropridine scaffold were designed and synthesized by multicomponent reactions (mcrs) to enhance pi-pi stacking. the synthesized compounds were identified by (1)h nmr, (13)c nmr, high-resolution mass spectroscopy, and elemental analysis. bioassay tests showed that some of them exhibited high insecticidal activities against pea aphid ( aphis craccivora ). | 2010 | 20000775 |
| two independent resistance genes in the medicago truncatula cultivar jester confer resistance to two different aphid species of the genus acyrthosiphon. | | 2009 | 19794854 |
| using the pea aphid acrythociphon pisum as a tool for screening biological responses to chemicals and drugs. | though the biological process of aphid feeding is well documented, no one to date has sought to apply it as a tool to screen the biological responses to chemicals and drugs, in ecotoxicology, genotoxicology and/or for interactions in the cascade of sequential molecular events of embryogenesis. parthenogenetic insect species present the advantage of an anatomical system composed of multiple germarium/ovarioles in the same mother with all the intermediate maturation stages of embryos from oocyte t ... | 2009 | 19758439 |
| reproductive responses of invasive and native predatory lady beetles (coleoptera: coccinellidae) to varying prey availability. | as adults, many predatory insects must adjust to a constantly changing prey environment while balancing between survival and reproduction. two laboratory experiments were conducted to compare reproductive responses of females of two species of lady beetles, invasive coccinella septempunctata l. and native c. transversoguttata richardsoni (brown), in utah alfalfa fields to varying availability of prey. when both lady beetles were placed immediately on experimental diets after being collected from ... | 2009 | 19689911 |
| influences of pea morphology and interacting factors on pea aphid (homoptera: aphididae) reproduction. | it has been claimed that plant architecture can alter aphid reproductive rates, but the mechanism driving this effect has not been identified. we studied interactions between plant architecture, aphid density, environmental conditions, and nutrient availability on the reproduction of pea aphids [acyrthosiphon pisum (harris)] using four near-isogenic peas (pisum sativum l.) that differ in morphology. manipulations of aphid density (1, 5, and 10 adults per plant) allowed us to examine any effects ... | 2009 | 19689873 |
| profiling the repertoire of phenotypes influenced by environmental cues that occur during asexual reproduction. | the aphid acyrthosiphon pisum population is composed of different morphs, such as winged and wingless parthenogens, males, and sexual females. the combined effect of reduced photoperiodicity and cold in fall triggers the apparition of sexual morphs. in contrast they reproduce asexually in spring and summer. in our current study, we provide evidence that clonal individuals display phenotypic variability within asexual morph categories. we describe that clones sharing the same morphological featur ... | 2009 | 19635846 |
| seasonal photoperiodism regulates the expression of cuticular and signalling protein genes in the pea aphid. | seasonal photoperiodism in aphids is responsible for the spectacular switch from asexual to sexual reproduction. however, little is known on the molecular and physiological mechanisms involved in reproductive mode shift through the action of day length. earlier works showed that aphid head, but not eyes, directly perceives the photoperiodic signal through the cuticle. in order to identify genes regulating the photoperiodic response, a 3321 cdna microarray developed for the pea aphid, acyrthosiph ... | 2007 | 17785197 |
| large gene family expansions and adaptive evolution for odorant and gustatory receptors in the pea aphid, acyrthosiphon pisum. | gaining insight into the mechanisms of chemoreception in aphids is of primary importance for both integrative studies on the evolution of host plant specialization and applied research in pest control management because aphids rely on their sense of smell and taste to locate and assess their host plants. we made use of the recent genome sequence of the pea aphid, acyrthosiphon pisum, to address the molecular characterization and evolution of key molecular components of chemoreception: the odoran ... | 2009 | 19542205 |
| the secreted salivary proteome of the pea aphid acyrthosiphon pisum characterised by mass spectrometry. | nine proteins secreted in the saliva of the pea aphid acyrthosiphon pisum were identified by a proteomics approach using ge-lc-ms/ms and lc-ms/ms, with reference to est and genomic sequence data for a. pisum. four proteins were identified by their sequences: a homolog of angiotensin-converting enzyme (an m2 metalloprotease), an m1 zinc-dependant metalloprotease, a glucose-methanol-choline (gmc)-oxidoreductase and a homolog to regucalcin (also known as senescence marker protein 30). the other fiv ... | 2009 | 19402045 |
| a continuum of genetic divergence from sympatric host races to species in the pea aphid complex. | sympatric populations of insects adapted to different host plants, i.e., host races, are good models to investigate how natural selection can promote speciation in the face of ongoing gene flow. however, host races are documented in very few model systems and their gradual evolution into good species, as assumed under a darwinian view of species formation, lacks strong empirical support. we aim at resolving this uncertainty by investigating host specialization and gene flow among populations of ... | 2009 | 19380742 |
| hitching a lift on the road to speciation. | understanding how speciation can take place in the presence of homogenizing gene flow remains a major challenge in evolutionary biology. in the early stages of ecological speciation, reproductive isolation between populations occupying different habitats is expected to be concentrated around genes for local adaptation. these genomic regions will show high divergence while gene exchange in other regions of the genome should continue relatively unimpaired, resulting in low levels of differentiatio ... | 2008 | 19378398 |
| discrimination of alarm pheromone (e)-beta-farnesene by aphid odorant-binding proteins. | obps have been recently demonstrated to be required for odour perception in insects and directly involved in odour discrimination. in aphids they might represent new interesting targets for the control of their population in agriculture. based on sequence information available in the est database, we have cloned four genes encoding odorant-binding proteins (obp) in acyrthosiphon pisum and homologous genes in other aphid species. unlike obps from other orders of insects, that are greatly divergen ... | 2009 | 19328854 |
| deterrence and toxicity of plant saponins for the pea aphid acyrthosiphon pisum harris. | plant saponins are widely distributed among plants and have a wide range of biological properties. three alfalfa saponins - zanhic acid tridesmoside, 3glca, 28ararhaxyl medicagenic acid glycoside, and 3glca, 28ararha medicagenic acid glycoside - were tested for their settling inhibition effects on feeding behavior of the aphid acyrthosiphon pisum using the electrical penetration graph method. application of saponins to artificial diets affected the insects' probing behavior. in general, saponins ... | 2007 | 17610116 |
| ecdysteroids from serratula wolffii roots. | two new natural ecdysteroids, 20,22-didehydrotaxisterone (1) and 1-hydroxy-20,22-didehydrotaxisterone (2), were isolated from the roots of serratula wolffii. their structures were elucidated by 1d and 2d nmr spectroscopy and mass spectrometry. the biological activities of these compounds were determined via oral aphid (acyrthosiphon pisum (harris)) tests. compound 1 was inactive and compound 2 exhibited very low toxicity in the oral aphid test. the activities of these two ecdysteroids were in ag ... | 2007 | 17417908 |
| inter- and intra-guild interactions related to aphids in nettle (urtica dioica l.) strips closed to field crops. | a field experiment designed to assess the biodiversity related to nettle strips closed to crops, and more particularly the aphid and related beneficial populations, was established in experimental farm located in gembloux (belgium). margin strips of nettle (urtica dioica) closed to wheat (triticum aestivum), green pea (pisum sativum) and rape (brassicae napus) fields were investigated. the diversity, abundance of aphids and related predators were analysed according to the plant crop species and ... | 2006 | 17385508 |
| host races of the pea aphid acyrthosiphon pisum differ in male wing phenotypes. | the evolution of reproductive isolation without geographic isolation (sympatric speciation) has recently gained strong theoretical and empirical supports. it is now widely admitted that many host-specific phytophagous insect species have arisen through shifting and adapting to new plants. the pea aphid acyrthosiphon pisum has received considerable attention in this context and is now considered as a probable case of incipient sympatric speciation through host specialization. in europe, three hos ... | 2010 | 19323853 |
| a positive trait-mediated indirect effect involving the natural enemies of competing herbivores. | trait-mediated indirect effects can have important effects on food web dynamics but are still poorly understood in the field. in a previous population cage study of a small community of aphids and an aphid natural enemy it was found that a trait-mediated indirect effect involving the natural enemy's behaviour was key to understanding community persistence. here evidence is presented that a related phenomenon involving some of the same species occurs in the field. surveys showed that two species ... | 2009 | 19214584 |
| developmental expression of apnanos during oogenesis and embryogenesis in the parthenogenetic pea aphid acyrthosiphon pisum. | among genes that are preferentially expressed in germ cells, nanos and vasa are the two most conserved germline markers in animals. both genes are usually expressed in germ cells in the adult gonads, and often also during embryogenesis. both nanos-first or vasa-first expression patterns have been observed in embryos, implying that the molecular networks governing germline development vary among species. previously we identified apvasa, a vasa homologue expressed in germ cells throughout all deve ... | 2009 | 19123140 |
| resource competition and shared natural enemies in experimental insect communities. | much theory has been developed to explore how competition for shared resources (exploitation competition) or the presence of shared natural enemies (apparent competition) might structure insect and other communities. it is harder to predict what happens when both processes operate simultaneously. we describe an experiment that attempted to explore how shared natural enemies and resource competition structured a simple experimental insect community. replicated communities were assembled in popula ... | 2009 | 19082628 |
| a water-specific aquaporin involved in aphid osmoregulation. | the osmotic pressure of plant phloem sap is generally higher than that of insect body fluids. water cycling from the distal to proximal regions of the gut is believed to contribute to the osmoregulation of aphids and other phloem-feeding insects, with the high flux of water mediated by a membrane-associated aquaporin. a putative aquaporin referred to as apaqp1 was identified by rt-pcr of rna isolated from the guts of pea aphids acyrthosiphon pisum. the apaqp1 protein has a predicted molecular ma ... | 2009 | 18983920 |
| wounding-mediated gene expression and accelerated viviparous reproduction of the pea aphid acyrthosiphon pisum. | most insects mount a potent antimicrobial defence upon contact with microbes or microbe-associated pattern molecules. using a combined set of methods for analysis of insect innate immunity, we report here that piercing of the pea aphid acyrthosiphon pisum with a bacteria-contaminated needle elicits lysozyme-like activity in the haemolymph but no detectable activities against live bacteria. confirming these results, we found no homologues of known antimicrobial peptides in our cdna library genera ... | 2008 | 18823444 |
| do aphid colonies amplify their emission of alarm pheromone? | when aphids are attacked by natural enemies, they emit alarm pheromone to alert conspecifics. for most aphids tested, (e)-beta-farnesene (ebf) is the main, or only, constituent of the alarm pheromone. in response to alarm pheromone, alerted aphids drop off the plant, walk away, or attempt to elude predators. however, under natural conditions, ebf concentration might be low due to the low amounts emitted, to rapid air movement, or to oxidative degradation. to ensure that conspecifics are warned, ... | 2008 | 18704588 |
| emission of alarm pheromone in aphids: a non-contagious phenomenon. | in response to attack by natural enemies, most aphid species release an alarm pheromone that causes nearby conspecifics to cease feeding and disperse. the primary component of the alarm pheromone of most species studied is (e)-beta-farnesene. we recently demonstrated that the production and accumulation of (e)-beta-farnesene during development by juvenile aphids is stimulated by exposure to odor cues, most likely by (e)-beta-farnesene emitted by other colony members. here, we tested whether the ... | 2008 | 18704587 |
| juvenile hormone titres and winged offspring production do not correlate in the pea aphid, acyrthosiphon pisum. | pea aphids, acyrthosiphon pisum, reproduce parthenogenetically and are wing-dimorphic such that offspring can develop into winged (alate) or unwinged (apterous) adults. alate induction is maternal and offspring phenotype is entirely determined by changes in the physiology and environment of the mother. juvenile hormones (jhs) have been implicated in playing a role in wing differentiation in aphids, however until recently, methods were not available to accurately quantify these insect hormones in ... | 2008 | 18634797 |
| a protein from the salivary glands of the pea aphid, acyrthosiphon pisum, is essential in feeding on a host plant. | in feeding, aphids inject saliva into plant tissues, gaining access to phloem sap and eliciting (and sometimes overcoming) plant responses. we are examining the involvement, in this aphid-plant interaction, of individual aphid proteins and enzymes, as identified in a salivary gland cdna library. here, we focus on a salivary protein we have arbitrarily designated protein c002. we have shown, by using rnai-based transcript knockdown, that this protein is important in the survival of the pea aphid ... | 2008 | 18621720 |
| whole-mount identification of gene transcripts in aphids: protocols and evaluation of probe accessibility. | in situ hybridization has become a powerful tool for detecting the temporal and spatial distribution of gene transcripts in prokaryotes and eukaryotes. we report an efficient protocol for whole-mount identification of the expression of mrnas in the parthenogenetic pea aphid acyrthosiphon pisum, an emerging model organism with a growing accumulation of genome sequencing data. in addition to steps common for most animal in situ hybridization protocols, we describe processing methods specific to ap ... | 2008 | 18481297 |
| first results on the insecticidal action of saponins. | in the search for new, natural insecticides, numerous scientists are currently trying to obtain useful compound from plants. a possibly interesting class of molecules are the saponins, a group of steroidal or triterpenoidal secondary plant metabolites with divergent biological activities. in this study, we investigated the activity of saponins against living caterpillars spodoptera littoralis) and aphids (acyrthosiphon pisum) via treatment on artificial diets containing different concentrations ... | 2007 | 18399498 |
| identification of aphid salivary proteins: a proteomic investigation of myzus persicae. | the role of insect saliva in the first contact between an insect and a plant is crucial during feeding. some elicitors, particularly in insect regurgitants, have been identified as inducing plant defence reactions. here, we focused on the salivary proteome of the green peach aphid, myzus persicae. proteins were either directly in-solution digested or were separated by 2d sds-page before trypsin digestion. resulting peptides were then identified by mass spectrometry coupled with database investig ... | 2008 | 18353105 |
| real-time analysis of alarm pheromone emission by the pea aphid (acyrthosiphon pisum) under predation. | upon attack by predators or parasitoids, aphids emit volatile chemical alarm signals that warn other aphids of a potential risk of predation. release rate of the major constituent of the alarm pheromone in pea aphids (acyrthosiphon pisum), (e)-b-farnesene (ebf), was measured for all nymphal and the adult stage as aphids were attacked individually by lacewing (chrysoperla carnae) larvae. volatilization of ebf from aphids under attack was quantified continuously for 60 min at 2-min intervals with ... | 2008 | 18092189 |
| the influence of natural enemies on wing induction in aphis fabae and megoura viciae (hemiptera: aphididae). | previous studies have shown that the aphid species, aphis fabae scopoli and megoura viciae buckton, do not produce winged offspring in the presence of natural enemies, in contrast to results for the pea aphid (acyrthosiphon pisum (harris)) and the cotton aphid (aphis gossypii glover); but these studies did not involve exposing aphids directly to natural enemies. we exposed colonies of both a. fabae and m. viciae to foraging lacewing (chrysoperla carnea (stephens)) larvae and found that the preda ... | 2008 | 18076776 |
| sex versus parthenogenesis: a transcriptomic approach of photoperiod response in the model aphid acyrthosiphon pisum (hemiptera: aphididae). | most aphids develop a cyclic parthenogenesis life-cycle. after several generations of viviparous parthenogenetic females, it 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 is a key factor inducing the sexual response. with the survey here reported we aimed at identifying a collection of candidate genes to participate at some point in the cascade of events that lead to the sexual ph ... | 2008 | 18065167 |
| analysis of heterochromatic epigenetic markers in the holocentric chromosomes of the aphid acyrthosiphon pisum. | monomethylated-k9 h3 histones (me9h3) and heterochromatin protein 1 (hp1) are reported as heterochromatin markers in several eukaryotes possessing monocentric chromosomes. in order to confirm that these epigenetic markers are evolutionarily conserved, we sequenced the hp1 cdna and verified the distribution of me9h3 histones and hp1 in the holocentric chromosomes of the aphid acyrthosiphon pisum. sequencing indicates that a. pisum hp1 cdna (called aphp1) is 1623 bp long, including a 170 bp long 5 ... | 2007 | 18004669 |
| large gene family expansion and variable selective pressures for cathepsin b in aphids. | aphids exclusively feed on plant phloem sap that contains much sugar and some nonessential amino acids but is poor in lipids and proteins. conventionally, it has been believed that aphids substantially have no intestinal digestion of proteins. however, we here report an unexpected finding that cysteine protease genes of the family cathepsin b are massively amplified in the lineage of aphids and that many of the protease genes exhibit gut-specific overexpression. by making use of expressed sequen ... | 2008 | 17934209 |
| strong heterogeneity in nucleotidic composition and codon bias in the pea aphid (acyrthosiphon pisum) shown by est-based coding genome reconstruction. | the aim of this study was to analyze patterns of nucleotidic composition and codon usage in the pea aphid genome (acyrthosiphon pisum). a collection of 60,000 expressed sequence tags (ests) in the pea aphid has been used to automatically reconstruct 5809 coding sequences (cdss), based on similarity with known proteins and on coding style recognition. reconstructions were manually checked for ribosomal proteins, leading to tentatively reconstruct the nea-complete set of this category. pea aphid c ... | 2007 | 17928936 |
| cross-species transferability of microsatellite markers from six aphid (hemiptera: aphididae) species and their use for evaluating biotypic diversity in two cereal aphids. | the abundance and distribution of microsatellites, or simple sequence repeats (ssrs) were explored in the expressed sequence tag (est) and genomic sequences of the pea aphid, acyrthosiphon pisum (harris), and the green peach aphid, myzus persicae (sulzer). a total of 108 newly developed, together with 40 published, ssr markers were investigated for their cross-species transferability among six aphid species. genetic diversity among six greenbug, schizaphis graminum (rondani) and two russian whea ... | 2007 | 17714463 |
| sex and death in the male pea aphid, acyrthosiphon pisum: the life-history effects of a wing dimorphism. | insect dispersal dimorphisms, in which both flight-capable and flightless individuals occur in the same species, are thought to reflect a balance between the benefits and costs of dispersal. fitness costs and benefits associated with wing dimorphism were investigated in the male pea aphid, acyrthosiphon pisum (harris) (hemiptera: aphididae). in one-on-one mating competitions in small arenas between winged and wingless males, the winged aphids obtained most of the matings with virgin females. in ... | 2007 | 20345312 |
| 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 ... | 2015 | 17651358 |
| comparison of radioimmunoassay and liquid chromatography tandem mass spectrometry for determination of juvenile hormone titers. | this paper compares the results of juvenile hormone (jh) titer determinations in two insect species, melanoplus sanguinipes, a migratory grasshopper, and acyrthosiphon pisum, the pea aphid, using a chiral-specific jh radioimmunoassay (ria) and liquid chromatography tandem mass spectrometry (lc-ms/ms), after extraction of jh with either hexane or isooctane-methanol. we compared results of jh titer determinations done on extracts of m. sanguinipes hemolymph taken from animals flown to exhaustion i ... | 2007 | 17628278 |
| molecular characterisation of a candidate gut sucrase in the pea aphid, acyrthosiphon pisum. | the hydrolysis of sucrose, the principal dietary source of carbon for aphids, is catalysed by a gut alpha-glucosidase/transglucosidase activity. an alpha-glucosidase, referred to as aps1, was identified in both a gut-specific cdna library and a sucrase-enriched membrane preparation from guts of the pea aphid acyrthosiphon pisum by a combination of genomic and proteomic techniques. aps1 contains a predicted signal peptide, and has a predicted molecular mass of 68 kda (unprocessed) or 66.4 kda (ma ... | 2007 | 17368194 |
| apvasa marks germ-cell migration in the parthenogenetic pea aphid acyrthosiphon pisum (hemiptera: aphidoidea). | in the parthenogenetic and viviparous pea aphid acyrthosiphon pisum, germline specification depends on the germ plasm localized to the posterior region of the egg chamber before the formation of the blastoderm. during blastulation, germline segregation occurs at the egg posterior, and in early gastrulation germ cells are pushed inward by the invaginating germ band. previous studies suggest that germ cells remain dorsal in the embryo in subsequent developmental stages. in fact, though, it is not ... | 2007 | 17333259 |
| the systemic effects of juvenoids on the red firebug pyrrhocoris apterus and on the pea aphid acyrthosiphon pisum with data on life table response. | a series of juvenoid alcohols and their glycosidic derivatives (juvenogens), synthesized at the institute of organic chemistry and biochemistry in prague, commercially used juvenoids and the natural derivatives of juvabione were evaluated for their systemic juvenilizing effect on the red firebug, pyrrhocoris apterus l., and on the pea aphid, acyrthosiphon pisum harris. a life table response experiment was designed, and demographic characteristics were computed for a cohort of a. pisum following ... | 2007 | 17724791 |
| characterization of a membrane-bound aminopeptidase purified from acyrthosiphon pisum midgut cells. a major binding site for toxic mannose lectins. | a single membrane-bound aminopeptidase n (apn) occurs in the pea aphid (acyrthosiphon pisum harris) midgut, with a ph optimum of 7.0, pi of 8.1 and molecular mass of 130 kda. this enzyme accounts for more than 15.6% of the total gut proteins. after being solubilized in detergent, apn was purified to homogeneity. the enzyme is a glycoprotein rich in mannose residues, which binds the entomotoxic lectins of the concanavalin family. the internal sequence of apn is homologous with a conservative doma ... | 2006 | 17212776 |
| predator avoidance behavior in the pea aphid: costs, frequency, and population consequences. | induced prey defenses can be costly. these costs have the potential to reduce prey survival or reproduction and, therefore, prey population growth. i estimated the potential for predators to suppress populations of pea aphids (acyrthosiphon pisum) in alfalfa fields through the induction of pea aphid predator avoidance behavior. i quantified (1) the period of non-feeding activity that follows a disturbance event, (2) the effect of frequent disturbance on aphid reproduction, and (3) the frequency ... | 2007 | 17066305 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| why short-term bioassays are not meaningful--effects of a pesticide (imidacloprid) and a metal (cadmium) on pea aphids (acyrthosiphon pisum harris). | the life-table study on effects of a heavy metal, cd (100 and 200 mg kg-1 soil), and an insecticide, imidacloprid (4 and 40 g a.i. ha-1), on pea aphids revealed significant effects of both chemicals on life history traits and population dynamics. substantial differences in the action of the two chemicals and between the two doses of imidacloprid were observed. the pesticide caused high mortality at the beginning of the experiment, however some aphids were able to live for as long as control inse ... | 2001 | 11383475 |
| an aphid-borne bacterium allied to the secondary symbionts of whitefly. | bacterial 16s rdna amplified by pcr from the pea aphid acyrthosiphon pisum included a sequence with >98% similarity to secondary symbionts in the whitefly bemisia tabaci. the 'pea aphid bemisia-like bacterium' (pabs) and b. tabaci secondary symbionts are estimated to have diverged 17-34 million years ago, a time considerably more recent than the common ancestor of aphids and whitefly and suggestive of horizontal transmission of this bacterial lineage. pabs was scored in both the gut and ovaries ... | 2001 | 11377772 |
| glutathione s-transferases of aulacorthum solani and acyrthosiphon pisum: partial purification and characterization. | glutathione s-transferases (gst) play an important role in the detoxification of many substances including allelochemicals from plants. brassicaceae plants contain glucosinolates and emit volatile isothiocyanates which affect the gst system. a comparison of the gst of two aphid species, the generalist aulacorthum solani found on brassicaceae and the fabaceae specialist acyrthosiphon pisum, was made to try to explain their respective feeding behaviour. differences of gst were determined among the ... | 2001 | 11337260 |
| effect of temperature and cultivar on pea aphid, acyrthosiphon pisum (hemiptera: aphididae) life history. | life history parameters of the pea aphid, acyrthosiphon pisum were studied at five constant temperatures on two cultivars of peas, scout and sancho. the development and mortality of juveniles and the life-span, age-specific fecundity and survivorship of adult aphids were recorded and used to construct life tables. the juvenile development period (from birth to adulthood) was longest at 11.9 degrees c (16.8 days on cv. scout and 16.2 days on cv. sancho) and shortest at 26.7 degrees c (8.5 days on ... | 2001 | 11228587 |
| chromosome analysis and molecular characterization of highly repeated dnas in the aphid acyrthosiphon pisum (aphididae, hemiptera). | despite the interest in aphid biology, information on chromatin organization of their holocentric chromosomes is still limited to few species. in order to fill this gap, we have performed an extensive survey on pea aphid mitotic chromosomes using both classical and molecular cytogenetic techniques. our results after silver, cma3 and dapi-staining, c-banding and fluorescent in situ hybridization (fish) using 28s rdna and 5s rdna as probes evidenced a tendency of repetitive dnas to be concentrated ... | 2000 | 11138948 |
| 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 |
| population differentiation and genetic variation in host choice among pea aphids from eight host plant genera. | habitat choice plays a critical role in the processes of host range evolution, specialization, and ecological speciation. pea aphid, acyrthosiphon pisum, populations from alfalfa and red clover in eastern north america are known to be genetically differentiated and show genetic preferences for the appropriate host plant. this species feeds on many more hosts, and here we report a study of the genetic variation in host plant preference within and between pea aphid populations collected from eight ... | 2006 | 17017058 |
| temporal habitat variability and the maintenance of sex in host populations of the pea aphid. | the evolutionary maintenance of sex, despite competition from asexual reproduction, has long intrigued the evolutionary biologists owing to its numerous apparent short-term costs. in aphids, winter climate is expected to determine the maintenance of sexual lineages in the high latitude zones owing to their exclusive ability to produce frost-resistant eggs. however, diverse reproductive modes may coexist at a local scale where climatic influence is counteracted by microgeographical factors. in th ... | 2006 | 17015368 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| a sex-linked locus controls wing polymorphism in males of the pea aphid, acyrthosiphon pisum (harris). | discrete variation in wing morphology is a very common phenomenon in insects and has been used extensively in the past 50 years as a model to study the ecology and evolution of dispersal. wing morph determination can be purely genetic, purely environmental, or some combination of the two. the precise genetic determinants of genetically based wing morph variation are unknown. here we explore the genetic basis of wing polymorphism in the pea aphid, which can produce either winged or wingless males ... | 2002 | 12399992 |
| interactions between extrafloral nectaries, aphids and ants: are there competition effects between plant and homopteran sugar sources? | broad bean (vicia faba), an annual plant bearing extrafloral nectaries (efn) at the base of the upper leaves, is regularly infested by two aphid species, aphis fabae and acyrthosiphon pisum. efn and a. fabae are commonly attended by the ant, lasius niger, while ac. pisum usually remains uninfested. sugar concentration and sugar composition of extrafloral nectar did not change significantly after aphid infestation. the sugar concentration was significantly higher in efn (c. 271 µg µl(-1)) than in ... | 2001 | 24577698 |
| genetic linkage of ecological specialization and reproductive isolation in pea aphids. | the evolution of ecological specialization generates biological diversity and may lead to speciation. genetic architecture can either speed or retard this process. if resource use and mate choice have a common genetic basis through pleiotropy or close linkage, the resulting genetic correlations can promote the joint evolution of specialization and reproductive isolation, facilitating speciation. here we present a model of the role of genetic correlations in specialization and speciation, and tes ... | 2001 | 11528477 |
| reproductive isolation between divergent races of pea aphids on two hosts. ii. selection against migrants and hybrids in the parental environments. | sympatric races of pea aphids on alfalfa and red clover are highly ecologically specialized and significantly reproductively isolated. much of the restriction of gene flow between the specialized populations is due to habitat choice behavior of the winged colonizers (via 1999). here, we document additional pre- and postmating reproductive isolation through selection against migrants and hybrids in the parental environments. first, a group of randomly chosen genotypes from each race that were exp ... | 2000 | 11108590 |
| clones of pea aphid, acyrthosiphon pisum (hemiptera: aphididae) distinguished using genetic markers, differ in their damaging effect on a resistant alfalfa cultivar. | cuf 101, a resistant cultivar of alfalfa, was exposed to 15 clones of acyrthosiphon pisum harris collected from alfalfa fields in three regions of france (east, south, central west) to determine whether the level of resistance varied across the different clones. the survival of alfalfa seedlings infested at the cotyledon stage was assessed using a standardized method. although no difference in seedling mortality was detected between clones grouped by region, there was a significant variation amo ... | 2000 | 10948361 |
| leaf surface waxbloom in pisum sativum influences predation and intra-guild interactions involving two predator species. | suppression of shared prey populations by insect predators can be influenced by interactions among these predators (intra-guild interactions). intra-guild interactions among predators attacking herbivores may be influenced by plant characteristics, but this possibility has not been examined. plant surface waxes are a ubiquitous and variable morphological feature that are known to affect insect predator behavior, and potentially in- fluence inter-predator interactions. to test this possibility we ... | 2000 | 28308186 |
| effect of nymphal diet on adult predation behavior in orius majusculus (heteroptera: anthocoridae). | the predatory bug orius majusculus (reuter) was reared on 2 different diets during the nymphal stages. the 1st group was exclusively offered eggs of ephestia kuehniella zeller (lepidoptera: pyralidae), a standard diet for o. majusculus production. the 2nd group was exclusively offered 4th instars of the pea aphid, acyrtosiphon pisum (harris). subsequently, adult predatory behavior in experimental arenas containing a. pisium was recorded using 2 video cameras. one camera permitted observation of ... | 2000 | 10826169 |
| salivary proteins of aphids, a pilot study on identification, separation and immunolocalisation. | salivary proteins (sps) of schizaphis graminum, acyrthosiphon pisum and myzus persicae were studied after probing and feeding on different artificial diets. salivary sheaths as well as apical lumps of saliva were found, presumably representing subsequently excreted saliva of different types. phenoloxidase, pectinase and peroxidase activities were detected by staining the enzyme-converted products, thus confirming these enzyme activities found earlier by others. proteinase and cellulase were not ... | 2000 | 10818245 |
| fate of dietary sucrose and neosynthesis of amino acids in the pea aphid, acyrthosiphon pisum, reared on different diets | the fate of sucrose, the major nutrient of an aphid's natural food, was explored by radiolabeling in the pea aphid acyrthosiphon pisum. to investigate the influence of nitrogen quality of food on amino acid neosynthesis, pea aphids were reared on two artificial diets differing in their amino acid composition. the first (diet a) had an equilibrated amino acid balance, similar to that derived from analysis of aphid carcass, and the other (diet b) had an unbalanced amino acid composition similar to ... | 1999 | 10482723 |
| importance of population structure at the time of toxicant exposure. | populations in nature often consist of a mixture of stages and ages, yet toxicological studies even demographic studies, usually evaluate one starting life stage. in this study it was asked whether the starting age/stage structure of a population at the time of initial pesticide exposure influenced the impact that pesticides have on population growth rates. this question was answered by exposing differently structured populations of two terrestrial arthropod species, the two-spotted spider mite, ... | 1999 | 10090817 |
| molecular evidence against phylogenetically distinct host races of the pea aphid (acyrthosiphon pisum). | pea aphid (acyrthosiphon pisum) clones have been shown to be adapted to particular host plant species but it is unknown whether there are host races. a 1101 base pair region of the mitochondrial cytochrome oxidase i gene (coi) was sequenced for 21 pea aphid clones that had been collected from different host plants in canada and the u.s.a. only five closely related mitochondrial haplotypes were found. a maximum likelihood phylogeny was estimated for these five haplotypes and four related aphid sp ... | 1998 | 9924789 |
| the developmental strategy of an idiobiont ectoparasitoid, dendrocerus carpenteri : influence of variations in host quality on offspring growth and fitness. | dendrocerus carpenteri (curtis) (hymenoptera: megaspilidae) is a solitary hyperparasitoid, which attacks prepupal and pupal stages of hymenopteran parasitoids inside mummified aphids. the larva feeds externally on the host, which is envenomed by the female at oviposition. to evaluate the influence of variations in host quality on the growth, development and fitness of d. carpenteri, we varied the size and developmental stage of the primary parasitoid host (aphidius ervi haliday), which was reare ... | 1998 | 28307914 |
| interactions between an introduced and indigenous coccinellid species at different prey densities. | coccinella septempunctata l. (coleoptera: coccinellidae), a palearctic coccinellid, has established and rapidly spread throughout the united states. this quantitative examination of larval interactions between c. septempunctata and coleomegilla maculata (degeer) (coleoptera: coccinellidae), a nearctic coccinellid, was conducted under controlled prey densities. larvae of both coccinellid species are affected by a limited diet [one pea aphid per day acyrthosiphon pisum (harris) (homoptera: aphidid ... | 1998 | 28308499 |
| the role of vision and color in the close proximity foraging behavior of four coccinellid species. | the role of vision and color in close-proximity foraging behavior was investigated for four species of lady beetles: coccinella septempunctata, hippodamia convergens, harmonia axyridis, and coleomegilla maculata. the effect of light level and color cues on consumption rates varied among the four predator species. the consumption rates of these predators on the pea aphid acyrthosiphon pisum (harris) was measured under light and dark conditions. c. septempunctata,h. convergens, and ha. axyridis co ... | 1998 | 28308464 |