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Aphid Clones (aphid + clone)

Distribution by Scientific Domains
Life Sciences50%

Selected Abstracts

The nature and reality of the aphid clone: genetic variation, adaptation and evolution

AGRICULTURAL AND FOREST ENTOMOLOGY, Issue 2 2008
Hugh D. Loxdale
Abstract 1,When aphid clones and clonality are discussed, it is still often said that they are ,genetically identical', a statement for which there is no direct evidence, and certainly not for the entire genome. By contrast, there is a growing body of empirical data from the application of high resolution molecular (DNA) markers that aphid asexual lineages rapidly mutate and that, in some documented cases, this variation is selectable, either positively or negatively. 2,Although it is true that, in enclosed conditions (e.g. laboratory or field cage), a so-called clone as defined as the asexual progeny of a single foundress may be traceable, this is rarely if ever possible in the field without the use of genetic markers, and even then, usually only at a relatively few loci (multilocus genotypes, ,MLGs'). 3,The continued use of the term clone without qualification of its true nature and the reality of its interesting biology is likely to hamper a proper understanding of the ecology and evolution of these insects (which are interesting in their own right because of their complex life histories, but also because they are important as major pests globally, both by causing direct feeding damage and by transmitting pathogenic plant viruses and thereby leading to huge economic losses in the agricultural, horticultural and forestry industries). 4,In this short review, I provide evidence of what is now known about aphid clonality after the widespread use of molecular markers, comprising information mainly gained within the last 15 years or so. 5,The data demonstrate widespread adaptation and evolution, sometimes involving introgression and hybridization. Because of this new knowledge, our ideas of what constitutes a clone are in need of serious re-evaluation. [source]

Impact of a parasitoid on the bacterial symbiosis of its aphid host

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 1 2003
Conrad Cloutier
Abstract Embryo production in aphids is absolutely dependent on the function of symbiotic bacteria, mainly Buchnera, and the growth and development of koinobiont parasitoids in aphids requires the diversion of nutrients from aphid embryo production to the parasitoid. The implication that the bacterial symbiosis may be promoted in parasitized aphids to support the growing parasitoid was explored by analysis of the number and biomass of mycetocytes, and the aphid cells bearing Buchnera, in the pea aphid Acyrthosiphon pisum Harris (Hemiptera: Aphididae) parasitized by the wasp Aphidius ervi Haliday (Hymenoptera: Braconidae). Aphids hosting a young larval parasitoid bore more mycetocytes of greater total biomass, and embryos of lower biomass than unparasitized aphids. Furthermore, one of the three aphid clones tested, which limited teratocyte growth (giant cells of parasitoid origin having a trophic role), bore smaller mycetocytes and larger embryos, than one or both of the two aphid clones with greater susceptibility to the parasitoid. These data suggest that susceptibility of the aphid- Buchnera symbiosis to parasitoid-mediated manipulation may, directly or indirectly, contribute to aphid susceptibility to parasitoid exploitation. [source]

The nature and reality of the aphid clone: genetic variation, adaptation and evolution

AGRICULTURAL AND FOREST ENTOMOLOGY, Issue 2 2008
Hugh D. Loxdale
Abstract 1,When aphid clones and clonality are discussed, it is still often said that they are ,genetically identical', a statement for which there is no direct evidence, and certainly not for the entire genome. By contrast, there is a growing body of empirical data from the application of high resolution molecular (DNA) markers that aphid asexual lineages rapidly mutate and that, in some documented cases, this variation is selectable, either positively or negatively. 2,Although it is true that, in enclosed conditions (e.g. laboratory or field cage), a so-called clone as defined as the asexual progeny of a single foundress may be traceable, this is rarely if ever possible in the field without the use of genetic markers, and even then, usually only at a relatively few loci (multilocus genotypes, ,MLGs'). 3,The continued use of the term clone without qualification of its true nature and the reality of its interesting biology is likely to hamper a proper understanding of the ecology and evolution of these insects (which are interesting in their own right because of their complex life histories, but also because they are important as major pests globally, both by causing direct feeding damage and by transmitting pathogenic plant viruses and thereby leading to huge economic losses in the agricultural, horticultural and forestry industries). 4,In this short review, I provide evidence of what is now known about aphid clonality after the widespread use of molecular markers, comprising information mainly gained within the last 15 years or so. 5,The data demonstrate widespread adaptation and evolution, sometimes involving introgression and hybridization. Because of this new knowledge, our ideas of what constitutes a clone are in need of serious re-evaluation. [source]

Genotype and temperature influence pea aphid resistance to a fungal entomopathogen

PHYSIOLOGICAL ENTOMOLOGY, Issue 2 2003
David A. Stacey
Abstract. The influence of temperature on life history traits of four Acyrthosiphon pisum clones was investigated, together with their resistance to one genotype of the fungal entomopathogen Erynia neoaphidis. There was no difference among aphid clones in development rate, but they did differ in fecundity. Both development rate and fecundity were influenced by temperature, but all clones showed similar responses to the changes in temperature (i.e. the interaction term was nonsignificant). However, there were significant differences among clones in susceptibility to the pathogen, and this was influenced by temperature. Furthermore, the clones differed in how temperature influenced susceptibility, with susceptibility rankings changing with temperature. Two clones showed changes in susceptibility which mirrored changes in the in vitro vegetative growth rate of E. neoaphidis at different temperatures, whereas two other clones differed considerably from this expected response. Such interactions between genotype and temperature may help maintain heritable variation in aphid susceptibility to fungal pathogen attack and have implications for our understanding of disease dynamics in natural populations. This study also highlights the difficulties of drawing conclusions about the efficacy of a biological control agent when only a restricted range of pest genotypes or environmental conditions are considered. [source]