Wilson, Daniel James (2019) The colonisation of vegetable and salad crops by aphids. PhD thesis, University of Warwick.

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Abstract

Aphids are some of the most damaging pests of horticultural crops globally. They cause direct feeding damage to crops and are key vectors of economically-important plant viruses. In the field, aphids are managed largely through the application of synthetic chemical insecticides. The sustainability of crop protection depends on optimising the use of available resources for aphid control. In the UK, this is particularly important due to recent declines in the availability of many insecticides and the increasing number of cases of insecticide resistance.

The project focused on the process of crop colonisation by several pest aphids of horticultural crops. Aphid phenology and disease risk were predicted through the use of forecasting models to warn of crop infestation and periods with potential for virus transmission. For Cavariella aegopodii, Cavariella pastinaceae, Cavariella theobaldi and Myzus persicae strong relationships were identified between air temperature and the timing of their migration. The models developed improve and/or expand on what is currently available to growers in the UK.

Once in crops, host plant selection by aphids and their responses to insecticides can have implications for the severity of infestations and virus transmission. The host preference behaviour of M. persicae was investigated. On Brussels sprout, aphids initiated probing behaviour more quickly, settled and fed more readily compared to carrot and lettuce.

Several synthetic chemical insecticides and compounds based on plant extracts were tested in terms of their effects on the survival and behaviour of alate M. persicae and the subsequent transmission of a non-persistent plant virus. Two of the test products induced high levels of mortality in M. persicae when applied prophylactically to plant surfaces. The persistence of these insecticides and the rapid knock-down of aphids may benefit the management of plant viruses.

Other treatments, including the pyrethroid insecticide, lambda-cyhalothrin, reduced aphid settling behaviour. Overall, the findings of the project can be used to refine Integrated Pest Management strategies for aphids by (i) targeting the use of insecticide treatments and (ii) informing the selection and sequence of insecticide treatments based on an improved understanding of their effects on aphid survival and behaviour.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	Q Science > QL Zoology S Agriculture > SB Plant culture
Library of Congress Subject Headings (LCSH):	Aphids -- Insecticide resistance, Aphids as carriers of disease, Field crops -- Diseases and pests, Agricultural pests
Official Date:	September 2019
Dates:	Date Event September 2019 UNSPECIFIED
Institution:	University of Warwick
Theses Department:	School of Life Sciences
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Collier, Rosemary
Sponsors:	Waitrose Agronomy Group ; University of Warwick
Format of File:	pdf
Extent:	xv, 265 leaves : illustrations
Language:	eng

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