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" Interactions among Plutella xylostella (L.) (Lepidoptera: Plutellidae), brassicaceous and non-brassicaceous host plants, and its larval parasitoids "
Muhammad Sarfraz
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Latin Dissertation
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| Language of Document
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English
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| Record Number
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54422
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TL24376
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| Call number
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NR46418
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| Main Entry
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Muhammad Sarfraz
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| Title & Author
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Interactions among Plutella xylostella (L.) (Lepidoptera: Plutellidae), brassicaceous and non-brassicaceous host plants, and its larval parasitoids\ Muhammad Sarfraz
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| College
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University of Alberta (Canada)
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| Date
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2008
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| Degree
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Ph.D.
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2008
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| Page No
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397
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| Abstract
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Interactions among the insect herbivore Plutella xylostella (L.), various plant species, and its parasitoids Diadegma insulare (Cresson) and Microplitis plutellae (Muesebeck) were studied in experiments designed to investigate bitrophic and tritrophic responses to soil fertility and host plant genotype. Different fertilizer applications significantly affected the nutrient contents of Brassica napus (L.) foliage, and this in turn affected performance of P. xylostella and D. insulare. Female P. xylostella discriminated among host plant fertility levels for oviposition, and selected plants on which pre-imaginal survival and development of their offspring was maximal, and on which new generation adults had highest longevity when food was limited. Host plant nutrient regime on which P. xylostella host larvae were reared also affected various developmental parameters of D. insulare. Regardless of soil fertility rate, plants responded to herbivory by increasing root mass relative to their non-infested counterparts. Bottom-up effects of host plant resistance on both P. xylostella and D. insulare were investigated through examination of several life history parameters when insects were reared on eight genetically different Brassicaceae, some of which were conventional hosts and others were herbicide-tolerant genotypes. Plutella xylostella is oligophagous, with a natural host plant range restricted to the Brassicaceae; the present study investigated the ecological costs and benefits that can arise when a herbivore species maintains the genetic plasticity within its population so it can occasionally shift from its normal hosts to exploit non-host species. Seasonal distribution patterns of P. xylostella, D. insulare and M. plutellae were investigated in commercial fields of canola in southern Alberta. This study used geographical information systems to determine the relationship between host plant quality, as assessed by tissue nutrient content, and field distributions of the herbivore and its parasitoids. Sampling P. xylostella, D. insulare and M. plutellae from points arranged in two grid patterns, together with the mapping and analysis of their spatial distributions over time generated a detailed picture of the pattern of crop colonization by the herbivore and its parasitoids. The studies have implications for improved management strategies for P. xylostella when the complex interactions among the different trophic levels are considered.
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| Subject
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Biological sciences; Plutella xylostella; Diadegma insulare; Microplitis plutellae; Lepidoptera; Brassicaceous; Organismal biology; 0353:Organismal biology
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University of Alberta (Canada)
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