Topic
Aphid
About: Aphid is a research topic. Over the lifetime, 11380 publications have been published within this topic receiving 229721 citations. The topic is also known as: Aphidoidea & plant lice.
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TL;DR: Aphid dispersion was manipulated in the field to determine how the different spatial patterns of the two species influenced reproduction and mortality, and hence the relative tendencies of their populations to irrupt, and found that feeding in large colonies provided no reproductive advantage to either species.
Abstract: Two aphid species, Uroleucon nigrotuberculatum and U. caligatum, that feed on the goldenrod Solidago altissima, are similar in life histories and feeding habits, but differ markedly in their spatial distribution and temporal variability. In this study, U. caligatum typically occurred in small colonies scattered throughout goldenrod fields, and its numbers remained relatively constant through time, whereas U. nigrotuberculatum occurred in dense colonies and exhibited greater fluctuations in population size. The aggregated spatial pattern of U. nigrotuberculatum resulted from both active aggregation of alates and lack of dispersal by apterae and nymphs. Field experiments in which colony size was held constant revealed that U. nigrotuberculatum enjoyed no clear reproductive advantage that might explain its greater tendency to outbreak. In addition, U. nigrotubercultatum was more susceptible to generalist predators (such as cantharid beetles, mirid bugs, and mites) than U. Caligatum. Aphid dispersion was then manipulated in the field to determine how the different spatial patterns of the two species influenced reproduction and mortality, and hence the relative tendencies of their populations to irrupt. Feeding in large colonies provided no reproductive advantage to either species. Aggregation did, however, enhance aphid survivorship when generalist predators were the main mortality agents. The advantage was reversed later in the season when the aphids' fungal pathogen was present; aggregation then led to a decrease in survivorship. Thus, aggregation allowed a numerical escape from generalist predators but also promoted fungal epidemics, so that the temporal variability in U. nigrotuberculatum populations was largely a consequence of its spatial distribution.
72 citations
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TL;DR: 1. Phenotypic diversity is the fuel that powers evolution.
Abstract: 1. Phenotypic diversity is the fuel that powers evolution.
2. Asexual organisms rely on mutation whereas sexual organisms combine mutation with recombination.
3. Few organisms provide examples of species that are both sexual and asexual, but aphids do.
4. To examine evolution on perceptible timescales requires strong evolutionary forces and, as Darwin noted, agricultural practices provide strong selection. In the case of aphids, insecticides provide a considerable force in the elimination of genotypes.
5. Insecticide resistance in Myzus persicae (Sulzer) has arisen independently through point mutation and gene amplification on a number of occasions and at different times. Resistance to organophosphates, pyrethroids, and pirimicarb (a dimethyl carbamate) is now widespread.
6. In this paper, we examine these three elements: sexual recombination, clonal expansion, and insecticide selection in the peach–potato aphid M. persicae in relation to the evolution of insecticide resistance and survival of the fittest clone.
72 citations
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TL;DR: The potential of adult and larval C. septempunctata to vector the aphid-specific entomopathogenic fungus E. neoaphidis was assessed through a series of laboratory and field experiments and the ability of coccinellids to vector conidia was demonstrated.
Abstract: The potential of adult and larval C. septempunctata to vector the aphid-specific entomopathogenic fungus E. neoaphidis was assessed through a series of laboratory and field experiments. The ability of coccinellids to vector conidia from a colony of E. neoaphidis -infected pea aphids, Acyrthosiphon pisum, to a colony of uninfected A. pisum was demonstrated in a laboratory study. Adult coccinellids which had previously foraged on plants infested with different densities of sporulating cadavers (1, 5, 15, 30 cadavers per plant) initiated infection in a proportion of uninfected pea aphids (4, 0, 2 and 8%, respectively) when subsequently allowed to forage on A. pisum infested bean plants. Further laboratory studies demonstrated that fourth instar larvae and adult coccinellids artificially inoculated with conidia initiated infection in 11 and 13% of an A. pisum population in which they foraged, respectively. Furthermore, a proportion of A. pisum placed on bean plants which had previously been foraged on by inoc...
72 citations
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TL;DR: A simulation model was developed to forecast aphid outbreaks and epidemics of CMV in lupin crops growing in the 'grainbelt' of south-west Australia, which has a Mediterranean-type climate, and can serve as a template for modelling similar virus/aphid vector pathosystems in other regions of the world, especially those with Mediterranean- type climates.
72 citations
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TL;DR: At least two genetic loci contribute to the high aphid resistance observed in the seedlings of maize inbred line Mo17, and one of these loci increases the biosynthesis of defence-related benzoxazinoids.
Abstract: Plants show considerable within-species variation in their resistance to insect herbivores. In the case of Zea mays (cultivated maize), Rhopalosiphum maidis (corn leaf aphids) produce approximately twenty times more progeny on inbred line B73 than on inbred line Mo17. Genetic mapping of this difference in maize aphid resistance identified quantitative trait loci (QTL) on chromosomes 4 and 6, with the Mo17 allele reducing aphid reproduction in each case. The chromosome 4 QTL mapping interval includes several genes involved in the biosynthesis of DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one), a maize defensive metabolite that also is required for callose accumulation in response to aphid feeding. Consistent with the known association of callose with plant defence against aphids, R. maidis reproduction on B73×Mo17 recombinant inbred lines was negatively correlated with both DIMBOA content and callose formation. Further genetic mapping, as well as experiments with near-isogenic lines, confirmed that the Mo17 allele causes increased DIMBOA accumulation relative to the B73 allele. The chromosome 6 aphid resistance QTL functions independently of DIMBOA accumulation and has an effect that is additive to that of the chromosome 4 QTL. Thus, at least two separate defence mechanisms account for the higher level of R. maidis resistance in Mo17 compared with B73.
72 citations