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Understanding interactions between biopesticides and partial crop resistance for management of aphid pests of Brassica crops
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Gladman, Andrew Karl (2022) Understanding interactions between biopesticides and partial crop resistance for management of aphid pests of Brassica crops. PhD thesis, University of Warwick.
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Official URL: http://webcat.warwick.ac.uk/record=b3857660
Abstract
The cabbage aphid, Brevicoryne brassicae L., is a Brassica specialist, and is among the most damaging pests of vegetable Brassica crops, causing significant yield losses due to direct feeding damage, virus transmission and crop contamination. It is normally managed using synthetic chemical pesticides. However, with emerging reports of insecticide-resistant B. brassicae clones and withdrawal of insecticides from the market because of environmental concerns, there is a need for alternative, sustainable approaches. In this project, a novel Integrated Pest Management (IPM) system was developed and evaluated, combining partially aphid resistant Brassica accessions with entomopathogenic fungi (EPF). In recent years it has been suggested that host plant resistance and biological controls such as EPF may interact favourably, resulting in greater than additive control. It was hypothesised that partial host plant resistance may extend the window of opportunity for successful EPF infection resulting in significantly higher levels of control. Through pre-selecting and screening a range of Brassica accessions, partially resistant accessions were identified which limited B. brassicae population development by approximately one third. Assessment of aphid life history traits showed that partial resistance significantly reduced the rate of juvenile aphid development, aphid weight and adult reproduction. Laboratory bioassays of 10 isolates of EPF showed that all were pathogenic to B. brassicae adults but were largely ineffective against nymphs with the exception of one isolate of Akanthomyces dipterigenus, which was highly virulent to nymphs. Experiments indicated that this may have resulted from faster germination and growth compared to other isolates. In experiments where B. brassicae were reared on partially resistant Brassica accessions and treated with the EPF A. dipterigenus or Beauveria bassiana, it was found that partial host plant resistance caused nymphs to become significantly more susceptible to infection by B. bassiana relative to nymph cohorts on more aphid-susceptible plants. Combining partial resistance with A. dipterigenus caused a significant increase in aphid population control as a result of a plant x EPF interaction. The results of this study demonstrate the potential of this combined IPM strategy, with the effects of partial resistance upon B. brassicae able to activate or improve EPF virulence to aphid nymphs, which appear to be the primary challenge for aphid control using EPF.
Item Type: | Thesis (PhD) | ||||
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Subjects: | Q Science > QL Zoology S Agriculture > SB Plant culture |
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Library of Congress Subject Headings (LCSH): | Cabbage aphid, Natural pesticides, Field crops -- Disease and pest resistance | ||||
Official Date: | January 2022 | ||||
Dates: |
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Institution: | University of Warwick | ||||
Theses Department: | School of Life Sciences | ||||
Thesis Type: | PhD | ||||
Publication Status: | Unpublished | ||||
Supervisor(s)/Advisor: | Chandler, Dave ; Teakle, Graham R. | ||||
Sponsors: | Midlands Integrative Biosciences Training Partnership ; Biotechnology and Biological Sciences Research Council (Great Britain) | ||||
Format of File: | |||||
Extent: | xxiii, 345 pages : colour illustrations | ||||
Language: | eng |
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