Sampson, Clare (2014) Management of the western flower thrips on strawberry. Doctoral thesis, Keele University.

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Abstract

The western flower thrips, Frankliniella occidentalis (Pergande), is an increasing problem in UK strawberry crops. The use of polythene tunnels has provided a more favourable environment for the pest, and pesticide-resistant strains have resulted in control failure. There is a need for improved knowledge of thrips biology and for additional control methods that can be integrated with natural enemies in order to make thrips management programmes more robust. The distribution of, and damage caused by, F. occidentalis was investigated to improve monitoring and decision-making, and the viability of using traps as a control was tested. Over 74% of adult thrips on plants were in flowers. Twice as many adult thrips were found in mature flowers at the top of the plant compared to those at the side. The distribution of larvae between flower and fruit stages varied with thrips density. All stages of flower and fruit were susceptible to damage but thrips larvae caused more damage than adults per individual, so the distribution and numbers of larvae between fruit stages best predicted the timing of damage. The predatory mite Neoseiulus cucumeris Oudemans reduced damage by feeding on thrips larvae. Economic crop loss occurred at five adult thrips per flower in the absence of N. cucumeris, but up to about 11 adult thrips per flower with good mite establishment. Adult F. occidentalis females overwintered on strawberry and on weeds, resulting in more thrips in second-year than in first-year crops. Mass trapping using blue sticky roller traps caught sufficient adult thrips to reduce fruit damage by 55-68% and increased grower returns by an estimated £2.2k per hectare. The addition of the F. occidentalis aggregation pheromone, neryl (S)-2-methylbutanoate, to the traps doubled the trap catch, but a visual stimulus was essential for trapping. (R)-lavandulyl acetate reduced trap catch, suggesting that it is not part of the aggregation pheromone.

Item Type: Thesis (Doctoral)
Subjects: S Agriculture > S Agriculture (General)
S Agriculture > SB Plant culture
Divisions: Faculty of Medicine and Health Sciences > Institute for Science and Technology in Medicine
Depositing User: Michael Debenham
Date Deposited: 24 Aug 2016 14:55
Last Modified: 24 Aug 2016 14:55
URI: http://eprints.keele.ac.uk/id/eprint/2133

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