Dissertations / Theses on the topic 'Pea aphid'
To see the other types of publications on this topic, follow the link: Pea aphid.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Pea aphid.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
McVean, Ross Iolo Kester. "Forecasting pea aphid outbreaks." Thesis, University of East Anglia, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389386.
Full text
2
François, Camille LeÌonie Marie JoseÌ€phe. "The pea aphid (Acyrthosiphon pisum) and its microorganisms." Thesis, University of York, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440793.
Full text
3
Aksamit, Matthew Stephen. "Bioinformatic analysis of pea aphid salivary gland transcripts." Thesis, Kansas State University, 2014. http://hdl.handle.net/2097/32836.
Full textAbstract:
Master of ScienceBiochemistry and Molecular Biophysics Interdepartmental Program
Gerald Reeck
Pea aphids (Acyrthosiphon pisum) are sap-sucking insects that feed on the phloem sap of some plants of the family Fabaceae (legumes). Aphids feed on host plants by inserting their stylets between plant cells to feed from phloem sap in sieve elements. Their feeding is of major agronomical importance, as aphids cause hundreds of millions of dollars in crop damage worldwide, annually. Salivary gland transcripts from plant-fed and diet-fed pea aphids were studied by RNASeq to analyze their expression. Most transcripts had higher expression in plant-fed pea aphids, likely due to the need for saliva protein in the aphid/plant interaction. Numerous salivary gland transcripts and saliva proteins have been identified in aphids, including a glutathione peroxidase. Glutathione peroxidases are a group of enzymes with the purpose of protecting organisms from oxidative damage. Here, I present a bioinformatic analysis of pea aphid expressed sequence tag libraries that identified four unique glutathione peroxidases in pea aphids. One glutathione peroxidase, ApGPx1 has high expression in the pea aphid salivary gland. Two glutathione peroxidase genes are present in the current annotation of the pea aphid genome. My work indicates that the two genes need to be revised.
4
Humphreys, Natalie J. "Symbiotic bacteria and aphid reproduction." Thesis, University of York, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337631.
Full text
5
Liang, Qixin. "Laccase-1 in the pea aphid, Acyrthosiphon pisum (Harris)." Thesis, Manhattan, Kan. : Kansas State University, 2006. http://hdl.handle.net/2097/172.
Full text
6
Whithead, Lynne F. "The symbiotic bacteria of the pea aphid, Acyrthosiphon pisum." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333293.
Full text
7
Kanvil, Sadia. "Pea aphid virulence factors determining compatibility with Medicago truncatula." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/39392.
Full text
8
Knaebe, Silvio. "The ecology of the subspecies of the pea aphid." Thesis, University of East Anglia, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302205.
Full textAbstract:
The pea aphid (Acyrthosiphon pisum) was one of the first aphid species for which different biotypes were described. Subsequently, the differences between biotypes were found to be consistent in time and space and several of them were given subspecies status. The differences between the subspecies is mainly ecological, their use of certain plants (the so-called marker hosts). There are hardly any differences in the morphology of the subspecies with the exception of that from Restharrow (Ononis spec. ). The performance and survival of aphids on several host plants were used to determine the degree of separation between the pea aphid subspecies and their marker hosts. To confirm the genetic basis of the host plant relations of the subspecies they were crossed. Few of the crosses showed hybrid dysfunction. The performance and survival of the hybrid clones confirmed that host plant relationships were genetically determined. There was also indication of a trade off. However, there was no indication that "Hopkin's host selection principle" played a big role in the utilisation of non-preferred host plants, with possible exception of clover. The different taxa differ significantly in body sizes. Clones from crop plants were generally bigger than those from wild plants. The genetic component of the size difference accounted for nearly 50 percent of the variances in size in wild clones. By comparing the performance of reciprocal crosses between subspecies on the marker hosts of the parents, no evidence was found that the specialised symbionts are specialised for particular marker hosts. This indicates that the aphid's genotype is the main determinant of host plant usage in the pea aphids. Furthermore, these aphids prefer their respective marker hosts. The connection between preferencea ndp erformancew as partly broken by hybridising the subspecies. The only subspecies that produces winged males and therefore has the ability to colonise other host plants, and thus the opportunity to mate with females of other subspecies, preferred sexual females of its own subspecies. The separation of the subspecies is further enhanced by the behaviour of egg laying females, which preferred to oviposit on their marker hosts. Hatching time of the eggs was also associated with the ecology of their marker host plants and probably the life history of the aphid, i.e. the subspecies that host alternates hatched first. The ecological separation between the subspecies was not confirmed by a molecular analysis, which even failed to separate the morphologically distinct subspecies from Ononis from the others taxa. The pea aphid complex is a good example of sympatric taxa, which is isolated from one another by their preference for particular marker hosts. That is, host plant is the main pre-zygotic separation mechanism, which is likely to lead the development of post-zygotic separation mechanism and eventually to fully independent species.
9
Ferrari, Julia. "Evolution of resistance to natural enemies." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272403.
Full text
10
Slater, Jennifer M. "Effects of the maternal rearing environment on pea aphid (Acyrthosiphon pisum) trophic interactions." Thesis, University of Aberdeen, 2018. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=238395.
Full textAbstract:
The maternal rearing environment (MRE) of an organism can be a key determinant of an organism's host choice decisions, its own fitness, or the fitness of its offspring. Here, it is investigated if the MRE of an organism can influence lower or higher trophic levels. A series of reciprocal cross-over experiments was conducted using pea aphids (Acyrthosiphon pisum), bean (Vicia faba) or pea (Pisum sativum) plants, and an aphid natural enemy, the parasitoid wasp Aphidius ervi, as model organisms. In each experiment, pea aphid offspring experienced either the same or an alternative plant host to that experienced by their mothers. This PhD showed that the MRE of pea aphids and parasitoid wasps was not a main contributory factor of host choice decisions or offspring fitness but influenced mother parasitoid wasp fecundity. Additionally, the MRE of pea aphids influenced the foliar nutrient concentration of pea plants when infested with the aphid's offspring. First, over shorter infestation periods, variation in foliar nitrogen and essential amino acid concentrations of pea leaves could be explained by pea aphid MRE. Over longer infestation periods, variation in foliar nitrogen and essential amino acid concentrations of pea leaves was explained by a combination of pea aphid MRE and aphid genotype. Second, the 13C concentration of pea leaf tissue, an indicator of stomatal aperture and leaf water stress, varied with pea aphid MREs over longer infestation periods. However, stomatal conductance and the expression of abscisic acid-responsive genes did not vary in a manner that was consistent with leaf water stress. Additional components of an organism's maternal rearing conditions are considered, including symbioses, as a more realistic MRE compared with that observed in nature. Taking account of MREs could provide a better understanding of the factors influencing the fitness of many organisms interacting in natural and managed ecosystems.
11
Wilkinson, Thomas Lees. "Host plant utilization by the pea aphid (Acyrthosiphon pisum) symbiosis." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359556.
Full text
12
McLean, Ailsa H. C. "Host plant specialisation and secondary symbionts in the pea aphid." Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.533836.
Full text
13
Nelson, Erik Healy. "Population consequences of predator avoidance behavior in the pea aphid /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.
Full text
14
Barrette, Richard J. "Characterization of the mitochondrial DNA molecule of pea aphid, Acyrthosiphon pisum." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq24440.pdf.
Full text
15
Oliver, Kerry M. "The role of pea aphid bacterial symbionts in resistance to parasitism." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1031%5F1%5Fm.pdf&type=application/pdf.
Full text
16
Knowles, Tim C. "Alfalfa Aphid Complex." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 1998. http://hdl.handle.net/10150/146689.
Full textAbstract:
4 pp.The alfalfa aphid discussed in this publication includes blue alfalfa aphid, pea aphid, and the spotted alfalfa aphid. This publication discusses the biology of these alfalfa aphids, the damages they cause, the resistant varieties and biological control, and their monitoring and treatments.
17
Shibani, Nagla Mohamed. "Proteomic analysis of host responses to wounding and aphid infestation in pea." Thesis, University of the West of England, Bristol, 2017. http://eprints.uwe.ac.uk/31778/.
Full text
18
Madison, Rachael Marie. "Gene expression and the nutritional biology of the pea aphid, Acyrthosiphon pisum." Thesis, University of York, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.533518.
Full text
19
Mutti, Navdeep S. "Molecular studies of the salivary glands of the pea aphid, Acyrthosiphon pisum (Harris)." Diss., Manhattan, Kan. : Kansas State University, 2006. http://hdl.handle.net/2097/154.
Full text
20
Leonardo, Teresa Elizabeth. "Host plant specialization in the pea aphid : exploring the role of facultative symbionts /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.
Full text
21
Birkle, Lucinda. "A molecular characterisation of the mitochondria and bacteria of the pea aphid, Acyrthosiphon pisum." Thesis, University of York, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387619.
Full text
22
Buchman, Natalie L. "Influences of Pea Morphology and Interacting Factors on Pea Aphids (Acyrthosiphon pisum)." Ohio : Ohio University, 2008. http://www.ohiolink.edu/etd/view.cgi?ohiou1218819576.
Full text
23
Stewart, Sophie Alice. "Exploring effective, clone-specific resistance against the pea aphid (Acyrthosiphon pisum) in Medicago truncatula." Thesis, Imperial College London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.511842.
Full text
24
Balthazor, James. "Studies of human Armet and of pea aphid transcripts of saliva proteins and the Unfolded Protein Response." Diss., Kansas State University, 2015. http://hdl.handle.net/2097/35218.
Full textAbstract:
Doctor of PhilosophyBiochemistry and Molecular Biophysics Interdepartmental Program
Gerald R. Reeck
Armet is a bifunctional protein that is apparently universally distributed among multicellular animal species, vertebrate and invertebrate alike. A member of the Unfolded Protein Response, (UPR) Armet promotes survival in cells that are under endoplasmic-reticulum (ER) stress. I have carried out biophysical studies on human Armet looking for compounds that bind to Armet and hence could reduce its anti-apoptotic function, thus potentially joining the growing class of pro-apoptotic drugs. Performed primarily with 1H-15N HSQC NMR, ligand studies showed that approximately 60 of the 158 residues are potentially involved with binding. The 60 residues are distributed throughout both domains and the linker suggesting multi-domain interaction with the ligand. Circular dichroism studies showed heat denaturation in a two-step unfolding process with independent unfolding of both domains of Armet with Tm values near 68°C and 83 C with the C-terminal domain unfolding first, as verified by 1H-15N HSQC NMR measurements. I also provide the first identification of UPR transcripts in pea aphids, Acyrthosiphon pisum, the genetic model among aphids. I measured transcript abundance with hope of finding future transcriptional targets for pest mitigation. I identified 74 putative pea aphid UPR components, and all but three of the components have higher transcript levels in aphids feeding on plants than those that fed on diets. This activated UPR state is attributed to the need for saliva proteins for plant feeding. Because aphids are agriculturally significant pests, and saliva is pivotal to their feeding on host plants, genes that encode saliva proteins may be targets for pest mitigation. Here I have sought the aphid’s saliva proteome by combining results obtained in several laboratories by proteomic and transcriptomic approaches on several aphid species. With these data I constructed a tentative saliva proteome for the pea aphid by compiling, collating, and annotating the data from several laboratories. I used RNA-seq to verify the transcripts in pea aphid salivary glands, thus expanding the proposed saliva proteome from approximately 50 components to around 130 components, I found that transcripts of saliva proteins are upregulated during plant feeding compared to diet feeding.
25
Kushlan, Philip. "The Influence of Endosymbiont Metabolism on the Δ15N Value of the Pea Aphid, Acyrthosiphon pisum." Scholarly Repository, 2011. http://scholarlyrepository.miami.edu/oa_theses/264.
Full textAbstract:
The use of stable nitrogen isotope data in ecological and physiological studies is based in the assumption that nitrogen fractionates predictably during metabolism, leading to a broadly conserved pattern whereby consumers are isotopically enriched with respect to their diets. The application of stable isotope data to such studies is limited is by our understanding of the factors in that cause variability in the Δ15N values of consumers. In particular, parasites and fluid-feeders have been shown to demonstrate isotopic depletion with respect to their food sources. One factor that has been suggested to influence the Δ15N values seen in fluid-feeding consumers is the presence of endosymbionts and their contribution to nitrogen metabolism. The experiments described in this thesis directly test the hypothesis that the endosymbiotic bacteria Buchnera aphidicola is influencing the Δ15N value of the pea aphid on host alfalfa plants. Here I find that although aphids cured of their bacterial symbionts are less isotopically depleted than untreated aphids, they are still not enriched with respect to their phloem sap diet, indicating that endosymbiont metabolism alone is not responsible for the isotopic depletion observed in pea aphids. Metabolism of nitrogen in the pea aphid-Buchnera symbiosis has been well described with decades of physiological studies and with the publication of the pea aphid and Buchnera genomes. The two key features of metabolism in the pea aphid-Buchnera symbiosis are the recycling of waste ammonia by the aphid and the upgrading of the nonessential amino acids found in phloem sap to essential amino acids through collaborative metabolism between the pea aphid and Buchnera. Consistent with the described role of Buchnera in nitrogen metabolism, amino acid analyses of symbiotic and aposymbiotic aphids demonstrates an accumulation of the nonessential amino acids glutamine and glutamate and lower amounts of essential amino acids in the aposymbiotic aphids. I tested the influence of dietary amino acid profile on the Δ15N value of pea aphids and found that aphids are only isotopically depleted when they feed on diets with unbalanced amino acid compositions and are isotopically enriched when fed on a diet with a balanced profile of amino acids. I used isotopically labeled fructose to determine whether the difference in Δ15N value of pea aphids on diets of varying amino acid profiles is correlated to the amount of de novo amino acid synthesis occurring in the aphid. I found that there was a significantly higher incorporation of the labeled carbon backbone in the protein of pea aphids feeding on the unbalanced diets, supporting the idea that increased de novo amino acid synthesis are responsible for the differences in Δ15N values among aphids feeding on the two diets. The findings of this study highlight the influence of endosymbionts on the Δ15N values for pea aphids, demonstrate that dietary amino acid composition can influence the Δ15N value of pea aphids through the demand for metabolic upgrading of amino acids, and provide a model for the study of Δ15N values in systems where metabolism has been well characterized by experimental and genomic data.
26
Hopkins, D. P. "The chemical ecology of host plant associated speciation in the pea aphid (Acyrthosiphon pisum) (Homoptera: Aphididae)." Thesis, University of Sheffield, 2016. http://etheses.whiterose.ac.uk/11933/.
Full textAbstract:
Previous work on pea aphid (Acyrthosiphon pisum) host-plant associated races has attributed their divergence to genes involved in chemosensory functions and metabolism of chemicals. In this study the host plant metabolic processes that drive A. pisum host plant race formation were investigated. First, profiles of aphid acceptance of plants were developed using the electrical penetration graph (EPG) technique. The acceptance of four A. pisum clones from two host races, associated with Medicago sativa or Trifolium pratense, was profiled across nine Medicago and ten Trifolium plant species. Acceptance profiles correlated strongly with aphid performance on plants. Aphid acceptance profiles were then compared with untargeted metabolomic profiles of plants, using random forest regression. Analysis revealed a small number of compounds that explained a large proportion of the variation in the A. pisum races differential acceptance of plant species. Two of these compounds were identified using tandem mass spectroscopy as L-phenylalanine and L-tyrosine, suggesting a possible link to the expression of a specific plant metabolic pathway. M. sativa and T. pratense plants were then pre-exposed to two divergent A. pisum clones. Aphid responses to pre-exposed and control plants were then profiled using EPG. The results suggested that M. sativa and T. pratense plants differ in their fixed (constitutive) and dynamic (induced or suppressed) responses to aphid attack. Exposing M. sativa plants to A. pisum clones appeared to also cause a change in the concentration of L-tyrosine, further suggesting a role of plant metabolic pathways in A. pisum divergent acceptance behaviour. The same two aphid clones were tested to see if they responded positively or negatively to diets containing varied concentrations of L-phenylalanine or L-tyrosine, but no conclusive evidence of aphid repulsion or attraction was found. This project identified that elements of plant chemical ecology could underlie divergent selection among A. pisum host races.
27
Wilson, Alex, Helen Dunbar, Gregory Davis, Wayne Hunter, David Stern, and Nancy Moran. "A dual-genome microarray for the pea aphid, Acyrthosiphon pisum, and its obligate bacterial symbiont, Buchnera aphidicola." BioMed Central, 2006. http://hdl.handle.net/10150/610396.
Full textAbstract:
BACKGROUND:The best studied insect-symbiont system is that of aphids and their primary bacterial endosymbiont Buchnera aphidicola. Buchnera inhabits specialized host cells called bacteriocytes, provides nutrients to the aphid and has co-speciated with its aphid hosts for the past 150 million years. We have used a single microarray to examine gene expression in the pea aphid, Acyrthosiphon pisum, and its resident Buchnera. Very little is known of gene expression in aphids, few studies have examined gene expression in Buchnera, and no study has examined simultaneously the expression profiles of a host and its symbiont. Expression profiling of aphids, in studies such as this, will be critical for assigning newly discovered A. pisum genes to functional roles. In particular, because aphids possess many genes that are absent from Drosophila and other holometabolous insect taxa, aphid genome annotation efforts cannot rely entirely on homology to the best-studied insect systems. Development of this dual-genome array represents a first attempt to characterize gene expression in this emerging model system.RESULTS:We chose to examine heat shock response because it has been well characterized both in Buchnera and in other insect species. Our results from the Buchnera of A. pisum show responses for the same gene set as an earlier study of heat shock response in Buchnera for the host aphid Schizaphis graminum. Additionally, analyses of aphid transcripts showed the expected response for homologs of known heat shock genes as well as responses for several genes with unknown functional roles.CONCLUSION:We examined gene expression under heat shock of an insect and its bacterial symbiont in a single assay using a dual-genome microarray. Further, our results indicate that microarrays are a useful tool for inferring functional roles of genes in A. pisum and other insects and suggest that the pea aphid genome may contain many gene paralogs that are differentially regulated.
28
Boulain, Hélène. "Diversité, caractéristiques évolutives et rôles des effecteurs salivaires du puceron du pois dans l’interaction avec ses plantes hôtes." Thesis, Rennes, Agrocampus Ouest, 2017. http://www.theses.fr/2017NSARA082/document.
Full textAbstract:
Les effecteurs jouent un rôle fondamental lors des interactions antagonistes plantes-pathogènes en supprimant les défenses de la plante, permettant ainsi aux parasites de se développer. De tels effecteurs ont été caractérisés chez les insectes herbivores mais leur rôle dans la spécialisation à la plante reste méconnu. Les pucerons se nourrissent de la sève du phloème et injectent dans la plante des effecteurs salivaires. L'étude des patrons d’évolution des effecteurs, ainsi que la caractérisation de leurs fonctions sont nécessaires à la compréhension des mécanismes de spécialisation chez les pucerons. Au cours de ces travaux, nous avons cherché à identifier les effecteurs salivaires impliqués dans l'adaptation du puceron du pois, Acyrthosiphon pisum, à ses hôtes.Des approches évolutives, basées sur un nouveau catalogue de 740 effecteurs candidats surexprimés dans les glandes salivaires de A. pisum, ont révélé que certains d'entre eux évoluent rapidement et que l'expansion de familles multigéniques apparaît comme une source importante de diversité des effecteurs. En parallèle, ces travaux ont permis d'optimiser l'expression transitoire médiée par Agrobacterium dans le pois. Ce nouvel outil d'analyse fonctionnelle permet maintenant l'étude des effecteurs candidats afin d'identifier les effecteurs du puceron du pois impliqués dans l'adaptation à la plante hôteEffectors play fundamental roles in antagonistic plant-pathogen interactions mainly by suppressing plant defense and allow parasites to multiply on the plant. Some effectors have been characterized in herbivorous insects; however, their role to the evolution in plant specialization remains unknown. Aphids feed from phloem sap and inject salivary effectors into the host plant. Studying evolutionary patterns and characterizing functions of effectors appear as important steps toward unveiling the mechanisms of host plant specialization in aphids. This work sought to identify salivary effectors that are involved in plant specialization of the pea aphid, Acyrthosiphon pisum. Evolutionary approaches based on a new catalogue of 740 putative effectors that are up-regulated in salivary glands of A. pisum revealed that some of them evolve rapidly.Moreover, gene family expansion appear as an important source of novel effectors. In parallel, this work optimized Agrobacterium-mediated transient gene expression in pea to provide a new tool for functional analyses of pea aphid effectors. The construction of a comprehensive catalogue of A. pisum salivary effectors and evolutionary analysis of them provide new candidates in host plant adaptation. By using the gene expression tool now available in pea, functional characterization of candidates will help to identify the effectors that are involved in plant specialization of the pea aphid
29
Heerman, Matthew C. "Analysis of EST’s encoding pea aphid Acyrthosiphon pisum C002 & the effect of armet transcript knockdown in Tribolium castaneum." Thesis, Kansas State University, 2012. http://hdl.handle.net/2097/17148.
Full textAbstract:
Master of ScienceDepartment of Biochemistry
Gerald Reeck
Aphids mount a remarkable salivary secretion to overcome plant host defenses. Our group has previously reported a gene unique to aphids enriched in the salivary glands of the pea aphid A. pisum, C002, which is required for successful feeding on its host plant Vicia fava. Here I present an analysis of genetic variation within the available EST data for C002 in pea aphids. From 596 total ESTs, 332 are full-length, and segregate into 8 validated haplotypes based on the criteria I set in place to access the quality of EST data. Additionally, Armet, is a putative multi-functional gene implicated as a neurotrophic factor during development, and as a part of the unfolded protein response during stress. I employ RNA interference in the model organism T. castaneum to determine the effect of transcript knockdown during development from early in-star larval stages, through pupation, and its effect on adult emergence. I report that knockdown of Armet transcript significantly hinders the ability for beetles to emerge from the pupae.
30
Moravvej, Gholamhossein. "The responses of the pea aphid Acyrhosiphon to the nitrogen status of its host plant with reference to insecticide susceptibility." Thesis, University of Newcastle Upon Tyne, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369835.
Full text
31
Meyer, Amanda R. "Novel approaches for the chromatographic and electrophoretic separation of molecules." Diss., Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/1031.
Full text
32
Sanchez-Arcos, Carlos Fernando [Verfasser], Georg [Gutachter] Pohnert, and Jonathan [Gutachter] Gershenzon. "Legume chemistry and the specificity of the pea aphid (Acyrthosiphon pisum) host races / Carlos Fernando Sanchez-Arcos ; Gutachter: Georg Pohnert, Jonathan Gershenzon." Jena : Friedrich-Schiller-Universität Jena, 2018. http://d-nb.info/1170395732/34.
Full text
33
Schwarzkopf, Alexander [Verfasser], Jonathan [Gutachter] Gershenzon, Rolf G. [Gutachter] Beutel, and Jean-Christophe [Gutachter] Simon. "Electrophysiological localization of plant factors affecting pea aphid (Acyrthosiphon pisum) compatibility to host and non-host plants / Alexander Schwarzkopf ; Gutachter: Jonathan Gershenzon, Rolf G. Beutel, Jean-Christophe Simon." Jena : Friedrich-Schiller-Universität Jena, 2017. http://d-nb.info/1177600404/34.
Full text
34
Khudr, Mouhammad Shadi. "Interwoven tributaries : a community genetics platform for ecological interactions." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/interwoven-tributariesa-community-genetics-platform-for-ecological-interactions(1aae8f17-0652-43cc-b84e-59d9277c3625).html.
Full textAbstract:
Community genetics research investigates the influence of intra-specific genetic variation on species interactions. This rapidly growing research field consists of more than one approach to explore how a significant portion of the environment of a focal species is differentially defined by the expressed genomes of other interacting species. While the basic concept of community genetics is well supported empirically, there is still a set of pertinent issues in need of further investigation. The initial research addressed herein focused on the extent to which the magnitude of a community genetic effect can be moderated when acting in concert with other forces in nature, i.e. the interaction between community genetic effects and the effects of other eco-evolutionary processes such as competition and parasitism. Subsequent research investigated the impact of genetic variation of host plants in agro-ecosystems on the performance (reproductive success) and behaviour (distribution and feeding-site choice) of plant-associated pests such as aphids, especially when pests and their hosts were subject to plant-mediated interactions. In addition, the differential effects of Indirect Ecological Effects (IEEs) and Indirect Genetic effects (IGEs) on the emergence of shared (extended) phenotypes between natural enemies (i.e. biological control agents and phytophagous insects) were examined. I provide clear evidence for significant effects of the genetic variation of host plant on aphid performance, behaviour and intra- and inter-specific competition. My findings also give credence to the concept of reciprocal moderation between plant genotype and aphid competition. I also provide observations on competition that segues into less antagonistic and possibly into a more cooperative form of interaction. In addition, I establish novel systems of economically important crop genotypes, noxious sap-feeding aphid species and root-galling nematodes. I also devise an amalgamated approach to interpret the interwoven set of mechanisms that underpin the observations presented and conclusions drawn. I also provide further investigation on the role of Indirect Ecological Effects (IEEs) between root-knot nematodes and sap-feeding aphids, and demonstrate the influence of in-plant variation on the interaction between the spatially separated plant consumers. Furthermore, I use a quantitative genetic experimental design in order to demonstrate a differential impact of parasitoid genotype on the behaviour of its aphid host. As such, I provide some of the clearest evidence to date that the phenotype of an organism can be the product of the genes expressed in another organism via Inter-specific Indirect Genetic Effects (IIGEs). Finally, I conducted research on epiphytic bromeliads and their associated faunal communities in the tropics. Here I demonstrate that the influence of intra-specific genetic variation of the host plant on the associated ecological communities may be more universal than previously conceived, with a plausible role for such variation in the maintenance of biological diversity. My research provides evidence for the genetic basis of species interactions and, interestingly, a genetic basis for the evolutionary arms-race between foragers and their hosts. My doctoral work adds new evidence to the increasing literature on the evolutionary importance of (Genotype x Genotype) interactions and (Genotype x Genotype x Environment) interactions in shaping the dynamics of pest communities, which in turn can affect plant phenotype and can influence the properties and services of the focal ecosystem in which the inter-players live and interact.
35
Richard, Gautier. "Régulations chromatiniennes et transcriptionnelles impliquées dans le cycle de vie du puceron du pois." Thesis, Rennes, Agrocampus Ouest, 2017. http://www.theses.fr/2017NSARB130/document.
Full textAbstract:
Les pucerons sont des hémiptères ravageurs des cultures agronomiques particulièrement adaptés à leur environnement. Acyrthosiphon pisum (le puceron du pois) présente un cycle de vie basé sur l’alternance d’une reproduction sexuée ou asexuée en réponse à la photopériode. Ils présentent ainsi un polyphénisme de reproduction aboutissant à la formation de trois phénotypes distincts : femelles asexuées, femelles sexuées, et mâles. Ces derniers étant obtenus par élimination d’un chromosome X, A. pisum est une espèce hétérogamétique mâle présentant un système chromosomique XX chez les femelles et X0 chez les mâles. Le déséquilibre du nombre de chromosome X entre mâles et femelles engendré par cette hétérogamétie nécessite chez certains organismes d’être corrigé par des mécanismes de compensation de dose. Les polyphénismes et compensation de dose impliquent chez d’autres organismes des régulations transcriptionnelles notamment régulées par l’accessibilité de la chromatine.Ma thèse vise ainsi à étudier le polyphénisme de reproduction et la compensation de dose des pucerons sous l’angle d’analyses bio-informatiques de données d’expression des gènes (RNA-seq) et d’accessibilité de la chromatine (FAIRE-seq) dans le but de caractériser l’impact des mécanismes épigénétiques dans ces deux processus biologiques fondamentaux du cycle de vie des pucerons. Les résultats développés dans ma thèse ont permis de montrer d’une part la présence d’une compensation de dose chez le puceron du pois au niveau transcriptomique, supportée par une accessibilité accrue de la chromatine de l’unique X desAphids are hemipterous crops pests that are particularly adapted to their environment. Acyrthosiphon pisum (pea aphid) displays a life cycle based on the alternation of sexual or asexual reproduction in response to photoperiod. They thus exhibit a reproductive polyphenism resulting in the formation of three distinct phenotypes: asexual females, sexual females, and males. The latter being obtained by elimination of an X chromosome, A. pisum is a male heterogametic species with a XX chromosomal system in females and X0 in males. The X chromosome number between males and females caused by this heterogamy requires in some organisms to be corrected by dosage compensation mechanisms. Polyphenisms and dosage compensation both involve in other organisms transcriptional regulations that are notably regulated by the chromatin accessibility regulations. My thesis aims to study the reproductive polyphenism and dosage compensation in aphids in the context of bioinformatic analyzes of gene expressioThe results developed in my thesis have shown, on one hand, the presence of dose compensation in pea aphid at the transcriptomic level, which is supported by increased chromatin accessibility of the males’ single X in somatic cells. On the other hand, specific sites of chromatin opening between sexual and asexual embryos seem to participate in the definition of their reproduction mode by modulating the expression of certain genes and by allowing the fixation of transcription factors. Their analysis shows the involvement of ecdysone as a new hormonal pathway that may trigger sexual reproducti
36
Salgueiro, Sancha P. "Molecular studies on pea enation mosaic virus." Thesis, University of East Anglia, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317586.
Full text
37
West, Joan A. "Geography and genetics of ecological speciation in pea aphids." College Park, Md.: University of Maryland, 2008. http://hdl.handle.net/1903/8023.
Full textAbstract:
Thesis (Ph. D.) -- University of Maryland, College Park, 2008.Thesis research directed by: Behavior, Ecology, Evolution and Systematics Program. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
38
Hendry, Tory A., Kelley J. Clark, and David A. Baltrus. "A highly infective plant-associated bacterium influences reproductive rates in pea aphids." ROYAL SOC, 2016. http://hdl.handle.net/10150/617209.
Full textAbstract:
Pea aphids, Acyrthosiphon pisum, have the potential to increase reproduction as a defence against pathogens, though how frequently this occurs or how infection with live pathogens influences this response is not well understood. Here we determine the minimum infective dose of an environmentally common bacterium and possible aphid pathogen, Pseudomonas syringae, to determine the likelihood of pathogenic effects to pea aphids. Additionally, we used P. syringae infection to investigate how live pathogens may alter reproductive rates. We found that oral bacterial exposure decreased subsequent survival of aphids in a dose-dependent manner and we estimate that ingestion of less than 10 bacterial cells is sufficient to increase aphid mortality. Pathogen dose was positively related to aphid reproduction. Aphids exposed to low bacterial doses showed decreased, although statistically indistinguishable, fecundity compared to controls. Aphids exposed to high doses reproduced significantly more than low dose treatments and also more, but not significantly so, than controls. These results are consistent with previous studies suggesting that pea aphids may use fecundity compensation as a response to pathogens. Consequently, even low levels of exposure to a common plant-associated bacterium may therefore have significant effects on pea aphid survival and reproduction.
39
Valls, Aleix. "Effects of Temperature on Pea Aphids, their Host Plants, and their Parasitoids." Diss., North Dakota State University, 2018. https://hdl.handle.net/10365/27477.
Full textAbstract:
Temperature has the potential to alter every aspect of an organism?s biology. This is especially true when we focus on small ectotherms such as insects. Understanding the effects of temperature on insects is particularly important given that climate change scenarios predict changes in temperature across the globe. In Chapter 1 we explored the effects of heat shocks on a discrete host-parasitoid interaction, specifically asking what happens if the heat shock happened before, during or after the interaction. We found that heat shocks had a stronger negative effect when they occurred while the wasp was actively foraging. In a follow-up behavioral experiment, we observed that this result is likely caused by the heat shock quickly rendering the majority of wasps inactive. In Chapter 2 we tested how variation in temperature affects pea aphid population size and how the effect changes with average temperature. We compared the population size of pea aphids under constant and fluctuating temperature profiles across a cool temperature range (20C and 16C/24C) and a warm temperature range (28C and 24C/32C). We saw that in the cooler range, pea aphids in the constant and fluctuating temperature treatments had the same population size. However, the same was not true for the warmer temperatures. In that case, fluctuating temperature profiles produced smaller populations compared to the constant temperatures. In Chapter 3 we focused on the possible indirect effects of temperature on pea aphids mediated by the aphids? host plants. We performed five experiments where we manipulated the exposure temperature (16C, 24C, and 32C) for plants and aphids. While temperature had strong direct effects on aphids and also affected plant size, temperature had little to no indirect effects on pea aphid fecundity. While the idea of temperature change can seem straightforward, temperature effects on insects are not straightforward. Timing and variation of temperature change are important. Indirect effects though direct effects on hosts also are important. My work shows a number of approaches for investigating these different temperature effects to better understand what might happen to insects when climate changes.National Science Foundation (NSF). Grant Number 1241031
40
Pandharikar, Gaurav. "Symbiose fixatrice d'azote versus nutrition minérale azotée : conséquence sur l'interaction entre Medicago truncatula et le puceron du pois Acyrthosiphon pisum." Electronic Thesis or Diss., Université Côte d'Azur, 2020. http://theses.univ-cotedazur.fr/2020COAZ6005.
Full textAbstract:
Les symbiotes jouent un rôle crucial dans le phénotype de leur hôte et dans son adaptation à l'environnement. Cependant, jusqu'à récemment, les interactions plantes-insectes étaient étudiées sans tenir compte de la présence de bactéries symbiotiques chez les partenaires impliqués. De nouvelles découvertes ont démontré que les communautés racinaires et aériennes des plantes sont liées. Dans ce contexte, mon doctorat s'interroge sur la façon dont les interactions entre les espèces végétales et les insectes sont modulées par leurs symbiotes respectifs. Dans un premier temps, j'ai analysé le rôle de la symbiose fixatrice d'azote (NFS) chez la légumineuse Medicago truncatula (A17) dans l’interaction avec des lignées de pucerons du pois Acyrthosiphon pisum portant différents endosymbionts facultatifs (FS). Pour ce faire, j'ai comparé la croissance de plantes de M. truncatula inoculées avec la bactérie nodulante Sinorhizobium meliloti (NFS) ou arrosées avec une solution de nitrate (non inoculées ; NI) infestées par des lignées de pucerons du pois provenant d’un même clone génétique (YR2) soit sans FS ou avec Hamiltonella defensa, Serratia symbiotica ou Regiella insecticola. La croissance des plantes NSF et NI est réduite par l'attaque des pucerons, tandis que la croissance des pucerons (mais pas leur survie) a été fortement réduite sur les plants NFS. En présence de pucerons la capacité de fixation d'azote des plantes NFS est réduite suite à l’induction d’une sénescence précoce des nodules. Enfin, chez les plantes NFS, toutes les lignées de pucerons ont déclenché l'expression du gène Pathogenesis-Related-1 (PR1), un marqueur de la voie salicylique (SA), et du gène Proteinase inhibitor (PI), un marqueur de la voie jasmonique (JA), tandis que chez les plantes NI, seule l'expression de PR1 a été déclenchée. Ainsi, le statut symbiotique de la plante influence clairement les interactions plante-puceron et la réponse de la plante à l’infestation, alors que le statut symbiotique du puceron ne fait que moduler l'amplitude de cette réponse. Il a été démontré que le génotype de la plante et du puceron sont tous deux importants dans le résultat de leur interaction, j'ai donc étudié plus en détail comment la NFS affecte l'interaction entre différents génotypes de plantes et de pucerons. Pour cela, j'ai utilisé trois génotypes différents d’A. pisum dépourvus de FS (LL01, YR2, T3-8V1) et deux génotypes de M. truncatula (A17 et R108) en présence ou en absence S. meliloti. La performance de chaque génotype de puceron sur les deux génotypes de plantes et l'effet des différents génotypes de pucerons sur la croissance des plantes et la capacité de fixation de l'azote des plantes de SNF ont été mesurés. Nous avons également estimé la réponse de défense médiée par le génotype de M. truncatula déclenchée par les différents génotypes de pucerons en utilisant différents gènes marqueurs des voies de défense JA et SA. J'ai constaté que les génotypes plantes-insectes ainsi que la présence de S. meliloti affectent de manière significative les interactions plantes-aphides. Ainsi, les interactions génétiques interspécifiques entre la plante hôte et les pucerons ainsi que leur statut symbiotique peuvent influencer la dynamique de la population et la structure de la communauté. Ces résultats montrent que l'interaction plante-insecte est fortement influencée par la génétique des espèces et par leur statut symbiotique, ajoutant un nouveau niveau de complexité qui reste à explorerSymbionts play a crucial role in shaping their host phenotype and driving its adaptation to the environment. However, until recently plant-insect interactions were studied disregarding the symbiotic bacterial presence in the involved partners. New findings have now demonstrated that above- and belowground plant communities are linked through biotic interactions. In this context, my PhD questions how the interaction between plant-insect species are modulated by their respective symbionts. In the first part of my work I have analysed the effect of the nitrogen fixing symbiosis (NFS) in the leguminous Medicago truncatula (A17) in interaction with pea aphid Acyrthosiphon pisum lines bearing different facultative endosymbionts (FS). For this, first I have compared the growth of M. truncatula plants either inoculated with the nodules inducing bacteria Sinorhizobium meliloti (NFS) or supplemented with nitrate (non-inoculated; NI), infested with pea aphid lines derived from the same genetic clone (YR2) and bearing either no FS or Hamiltonella defensa, Serratia symbiotica or Regiella insecticola. As expected, growth of both NFS and NI plants was reduced by the aphid attack, while aphid growth (but not survival) was strongly reduced on NFS compared to NI plants. Interestingly, most aphid lines decreased the plant nitrogen fixation capacity of NFS plants by inducing an early nodule senescence. Finally, in NFS plants all aphid lines triggered the expression of Pathogenesis Related Protein 1 (PR1), a marker of the salicylic (SA) pathway, and of Proteinase Inhibitor (PI), a marker of the jasmonic (JA) pathway, while in NI plants only PR1 expression was triggered. Thus, the plant symbiotic status influences clearly the plant–aphid interactions and the plant response while the aphid symbiotic status only modulates the response amplitude. Since both plant and aphid genotypes are important in the outcome of their interaction, I further studied how plant symbiosis affect the plant-insect genotype x genotype interaction. For this, I used three different pea aphid genotypes devoid of FS (LL01, YR2, and T3-8V1) and two M. truncatula genotype (A17 and R108) combinations in the presence or absence of rhizobacteria. The performance of each aphid genotype on both plant genotypes and the effect of different aphid genotypes on the plant growth and nitrogen fixation capacity of NFS plants were measured. We also estimated M. truncatula genotype-mediated defence response triggered by the different aphid genotypes using multiple gene markers of the JA and SA defence-pathways. I found that the plant-insect genotypes as well as the rhizobacteria presence significantly affect plant-aphid interactions. These results show that the outcome of the plant-insect interaction is strongly impacted by the genotype of the species and by their symbiotic status, rising a new level of complexity that remains to be explored
41
Higashi, Susan. "MiRNA and co : methodologically exploring the world of small RNAs." Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10252/document.
Full textAbstract:
La principale contribution de cette thèse est le développement d'une méthode fiable, robuste, et rapide pour la prédiction des pré-miARNs. Deux objectifs avaient été assignés : efficacité et flexibilité. L'efficacité a été rendue possible au moyen d'un algorithme quadratique. La flexibilité repose sur deux aspects, la nature des données expérimentales et la position taxonomique de l'organisme (en particulier plantes ou animaux). Mirinho accepte en entrée des séquences de génomes complets mais aussi les très nombreuses séquences résultant d'un séquençage massif de type NGS de “RNAseq”. “L'universalité” taxonomique est obtenu par la possibilité de modifier les contraintes sur les tailles de la tige (double hélice) et de la boule terminale. Dans le cas de la prédiction des miARN de plantes la plus grande longueur de leur pré-miARN conduit à des méthodes d'extraction de la structure secondaire en tige-boule moins précises. Mirinho prend en compte ce problème lui permettant de fournir des structures secondaires de pré-miARN plus semblables à celles de miRBase que les autres méthodes disponibles. Mirinho a été utilisé dans le cadre de deux questions biologiques précises l'une concernant des RNAseq l'autre de l'ADN génomique. La première question a conduit au traitement et l'analyse des données RNAseq de Acyrthosiphon pisum, le puceron du pois. L'objectif était d'identifier les miARN qui sont différentiellement exprimés au cours des quatre stades de développement de cette espèce et sont donc des candidats à la régulation des gènes au cours du développement. Pour cette analyse, nous avons développé un pipeline, appelé MirinhoPipe. La deuxieme question a permis d'aborder les problèmes liés à la prévision et l'analyse des ARN non-codants (ARNnc) dans la bactérie Mycoplasma hyopneumoniae. Alvinho a été développé pour la prédiction de cibles des miRNA autour d'une segmentation d'une séquence numérique et de la détection de la conservation des séquences entre ncRNA utilisant un graphe k-partite. Nous avons finalement abordé un problème lié à la recherche de motifs conservés dans un ensemble de séquences et pouvant ainsi correspondre à des éléments fonctionnelsThe main contribution of this thesis is the development of a reliable, robust, and much faster method for the prediction of pre-miRNAs. With this method, we aimed mainly at two goals: efficiency and flexibility. Efficiency was made possible by means of a quadratic algorithm. Flexibility relies on two aspects, the input type and the organism clade. Mirinho can receive as input both a genome sequence and small RNA sequencing (sRNA-seq) data of both animal and plant species. To change from one clade to another, it suffices to change the lengths of the stem-arms and of the terminal loop. Concerning the prediction of plant miRNAs, because their pre-miRNAs are longer, the methods for extracting the hairpin secondary structure are not as accurate as for shorter sequences. With Mirinho, we also addressed this problem, which enabled to provide pre-miRNA secondary structures more similar to the ones in miRBase than the other available methods. Mirinho served as the basis to two other issues we addressed. The first issue led to the treatment and analysis of sRNA-seq data of Acyrthosiphon pisum, the pea aphid. The goal was to identify the miRNAs that are expressed during the four developmental stages of this species, allowing further biological conclusions concerning the regulatory system of such an organism. For this analysis, we developed a whole pipeline, called MirinhoPipe, at the end of which Mirinho was aggregated. We then moved on to the second issue, that involved problems related to the prediction and analysis of non-coding RNAs (ncRNAs) in the bacterium Mycoplasma hyopneumoniae. A method, called Alvinho, was thus developed for the prediction of targets in this bacterium, together with a pipeline for the segmentation of a numerical sequence and detection of conservation among ncRNA sequences using a kpartite graph. We finally addressed a problem related to motifs, that is to patterns, that may be composed of one or more parts, that appear conserved in a set of sequences and may correspond to functional elements
42
Joschinski, Jens [Verfasser], Jochen [Gutachter] Krauss, Flavio [Gutachter] Roces, and Thomas [Gutachter] Hovestadt. "Is the phenology of pea aphids (Acyrthosiphon pisum) constrained by diurnal rhythms? / Jens Joschinski ; Gutachter: Jochen Krauss, Flavio Roces, Thomas Hovestadt." Würzburg : Universität Würzburg, 2018. http://d-nb.info/115849694X/34.
Full text
43
Robinson, K. A. "Use of floral resources by the lacewing Micromus tasmaniae and its parasitoid Anacharis zealandica, and the consequences for biological control by M. tasmaniae." Diss., Lincoln University, 2009. http://hdl.handle.net/10182/823.
Full textAbstract:
Arthropod species that have the potential to damage crops are food resources for communities of predators and parasitoids. From an agronomic perspective these species are pests and biocontrol agents respectively, and the relationships between them can be important determinants of crop yield and quality. The impact of biocontrol agents on pest populations may depend on the availability of other food resources in the agroecosystem. A scarcity of such resources may limit biological control and altering agroecosystem management to alleviate this limitation could contribute to pest management. This is a tactic of ‘conservation biological control’ and includes the provision of flowers for species that consume prey as larvae but require floral resources in their adult stage. The use of flowers for pest management requires an understanding of the interactions between the flowers, pests, biocontrol agents and non-target species. Without this, attempts to enhance biological control might be ineffective or detrimental. This thesis develops our understanding in two areas which have received relatively little attention: the role of flowers in biological control by true omnivores, and the implications of flower use by fourth-trophic-level life-history omnivores. The species studied were the lacewing Micromus tasmaniae and its parasitoid Anacharis zealandica. Buckwheat flowers Fagopyrum esculentum provided floral resources and aphids Acyrthosiphon pisum served as prey. Laboratory experiments with M. tasmaniae demonstrated that although prey were required for reproduction, providing flowers increased survival and oviposition when prey abundance was low. Flowers also decreased prey consumption by the adult lacewings. These experiments therefore revealed the potential for flowers to either enhance or disrupt biological control by M. tasmaniae. Adult M. tasmaniae were collected from a crop containing a strip of flowers. Analyses to determine the presence of prey and pollen in their digestive tracts suggested that predation was more frequent than foraging in flowers. It was concluded that the flower strip probably did not affect biological control by lacewings in that field, but flowers could be significant in other situations. The lifetime fecundity of A. zealandica was greatly increased by the presence of flowers in the laboratory. Providing flowers therefore has the potential to increase parasitism of M. tasmaniae and so disrupt biological control. A. zealandica was also studied in a crop containing a flower strip. Rubidium-marking was used to investigate nectar-feeding and dispersal from the flowers. In addition, the parasitoids’ sugar compositions were determined by HPLC and used to infer feeding histories. Although further work is required to develop the use of these techniques in this system, the results suggested that A. zealandica did not exploit the flower strip. The sugar profiles suggested that honeydew had been consumed by many of the parasitoids. A simulation model was developed to explore the dynamics of aphid, lacewing and parasitoid populations with and without flowers. This suggested that if M. tasmaniae and A. zealandica responded to flowers as in the laboratory, flowers would only have a small effect on biological control within a single period of a lucerne cutting cycle. When parasitoids were present, the direct beneficial effect of flowers on the lacewing population was outweighed by increased parasitism, reducing the potential for biological control in future crops. The results presented in this thesis exemplify the complex interactions that may occur as a consequence of providing floral resources in agroecosystems and re-affirm the need for agroecology to inform the development of sustainable pest management techniques.
44
Huang, Ting-Yu, and 黃廷宇. "Anteroposterior axis determination in pea aphid Acyrthosiphon pisum." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/92826157416603238875.
Full textAbstract:
博士國立臺灣大學
生化科學研究所
99
Patterning insect embryos is controlled by a spectrum of well-conserved genes. Anteroposterior axis formation is well understood in Drosophila in which bicoid and caudal encode proteins that form morphogenetic gradients from both poles of the embryo and both of them play a key role in anterior and posterior patterning of the fruit fly embryo. However, recent studies suggest bicoid is an invention of new regulatory protein during the evolution. In some non-dipteran insects such as wasp (Nasonia vitripennis) and beetle (Tribolium castaneum), the anterior specification relies on a synergistic interaction between hunchback and orthodenticle. Evidence shown here indicates it is the asymmetric localization of Aphb rather than the synergistic interaction between Aphb and Apotd, which regulate the anterior development in the asexual pea aphid. Furthermore, unlike Drosophila caudal which forms a linear concentration gradient in early embryogenesis, Apcad does not show a gradient expression in early developmental stages. But, Apcad transcript is expressed in the posteriormost of the germ band in mid- and late- embryogenesis, and might involve in the germ cell formation in the pea aphid. In conclusion, Aphb, Apotd and Apcad exhibit some conserved features in later embryogenesis in the pea aphid as well as in other insects; however, they diverse in early oogenesis and embryogenesis. Compared to Drosophila which patterns most of its segments in syncytial blastoderm stage, most arthropods generate its segments from a celluarized environment. Here, three conserved segment polarity genes, engrailed-1, engrailed-2 and wingless have been cloned and illustrated the expression of their transcripts. It is shown that the first appearing segment is the third segment of thorax (T3), and then remaining segments add from head to abdomen sequentially. The expression of Apwg is also shown periodically and co-localized with Apcad transcript in the posterior of the germ band. It suggests that the segmentation mechanism in pea aphid might be conserved, similar to other short germ band insects. However, the possible regulation between genes which involve in axis formation (Aphb, Apotd, and Apcad) and genes which involve in segment formation (Apen-1, Apen-2, and Apwg) remains unclear and worthy of further investigation.
45
Soroka, Juliana. "Pea aphid, Acyrthosiphon pisum (Harris), populations on cultivars of field peas in Manitoba and their effects on pea yield." 1989. http://hdl.handle.net/1993/7195.
Full textAbstract:
The research for this project was undertaken from 1984 to 1987. Natural infestations of pea aphids, Acyrthosiphon pisum (Harris), were measured throughout the summer on five (1984) or six (1985, 1986) cultivars of field peas in small field plots near Glenlea, Manitoba. sarting from equal numbers of pea aphids per cage, in 1986 pea aphid populations were also monitored in 1 m3 field cages which contained plants of one of these six field pea cultivars. Throughout the summers of 1985 and 1986 pea aphids were also sampled in a total of nine Century, four Trapper and two Triumph commercial pea fields in several regions across the province. In all of these tests, pea aphid population growth patterns were similar among cultivars. Aphid numbers rose from low levels during the vegetative to blooming stages of plant growth in mid-July, peaked in late July or early August as pods developed and matured, and declined rapidly by mid- to late August as pea plants senesced. However, numbers of pea aphids at the time of population peak differed consistently and significantly with the cultivar upon which they grew. Peak numbers of pea aphids were larger on Triumph or Trapper plants than they were on Century or Tipu plants. In commercial fields, populations of pea aphids rose more rapidly on Trapper than they did on Century or Triumph plants. In field plots seed weight was the yield component most sensitive to aphid feeding. Triumph had significantly lower seed yields in infested than in control subplots in two out of three years. Seed weight was significantly reduced in infested subplots of Tara peas in one year. Because aphid numbers were low and generally occurred later than at flowering or pod initiation in Century peas, no yield losses due to pea aphids occurred in this cultivar in any of the tests. However, linear regression of seed weight over aphid density indicated that, of the cultivars tested, Century is most susceptible to increasing aphid numbers. Trapper seed weight was least related to aphid density despite the relatively high numbers of pea aphids occurring on this cultivar. In laboratory studies pea aphids had the greatest intrinsic rates of natural increase rm, on the cultivar Trapper and the smallest on the cultivars Tipu and Century. Ten days after infestation, the most antixenosis resistance was expressed by the cultivar Tipu, and the least by Triumph. After 20 days, Triumph still was most preferred by the aphid. Trapper appeared somewhat tolerant of the effects of pea aphid feeding.
46
Deneka, Barbara A. "Seasonal dispersal of the pea aphid parasitoid, Aphidius ervi Haliday." 1992. http://hdl.handle.net/1993/17997.
Full text
47
Akey, David Harold. "Nutrition and culture of the pea aphid, Acyrthosiphon pisum, on defined diets." 1994. http://catalog.hathitrust.org/api/volumes/oclc/32909304.html.
Full textAbstract:
Thesis (Ph. D.)--University of Wisconsin--Madison, 1972.Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.
48
Maiteki, George Alfred. "Seasonal abundance, damage assessment and economic threshold of the pea aphid, Acyrthosiphon pisum (Harris), on field peas in Manitoba." 1985. http://hdl.handle.net/1993/28794.
Full text
49
Heppler, Marty Leanne. "Pathogenicity of four Serratia marcescens to the pea aphid, Acyrthosiphon pisum, and the squash bug, Anasa tristis." 2007. http://digital.library.okstate.edu/etd/umi-okstate-2499.pdf.
Full text
50
Chung, Chen-yo, and 鍾成侑. "Exploration of non-canonical expression of developmental genes in the asexual viviparous pea aphid using fluorescence approaches." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/39194265777581632775.
Full textAbstract:
博士國立臺灣大學
昆蟲學研究所
102
The pea aphid Acyrthosiphon pisum is a genomic model insect and a unique model for polyphenism due to its developmental plasticity in response to environmental cues. To uncover the relation of embryonic development and gene regulations, reliable expression protocols and functional tools are required. Whole-mount in situ hybridization (WISH) we previously reported can be used to monitor gene expressions during embryogenesis, however chromogenic signals are defective in double detection of genes and construction of three-dimensional image. I therefore developed a fluorescent in situ hybridization (FISH) protocol to overcome these defects. By means of different advantages of four FISH methods, I successfully detected gene expressions in somatic and extraembryonic tissues. The combination of FISH methods also allowed the double detection of genes in somatic cells, germ cells, or both in one preparation. This FISH protocol further aids me in revealing the expression of developmental genes. In our previous findings, mRNA expression of A. pisum hunchback (Aphb), a Drosophila homolog of hunchback, was found in the segments and central nervous system of mid/late stages apart from the anterior pole of early stages, implicating its conserved roles among arthropods and lower organisms. Here I discovered a novel expression pattern of Aphb in germ cells of the pea aphid. Germline expression of Aphb initiates while primordial germ cells formed, and maintains throughout developmental stages. In late embryos, Aphb is also expressed in maturing germaria as well as the protruding oocytes. These findings implicate that the homolog of hb in aphids replaces the role of bicoid in anterior determination and, moreover, has the roles in formation of germ cells. To reveal whether the complex of Nanos (Nos) and Pumilio (Pum) is required to repress the translation of anterior-localized Aphb in the posterior, I analyzed the structure of A. pisum Pum (ApPum) protein and the expression patterns of Appum mRNA. The highly conserved protein structure indicates the ApPum can repress the translation of Aphb, though the asymmetric expression of Appum mRNA, like Drosophila pum, was not found. Together with the known expression patterns of Aphb, Appum, and A. pisum Nos (ApNos), it appears that posterior determination of the pea aphid relies on the ApNos/ApPum complex and the anterior is determined by Aphb.