Whilst not a ‘new’ pest in the UK, Aleyrodes proletella has become an increasing problem for the Brassica industry in recent years, especially on Brussels sprout and kale. The reason for the increasing problem is unknown, but it is believed to be due to a combination of climate change, removal of certain active ingredients from use and later harvest times of crops. Relatively little research has focused on this species as, historically; it has been regarded as a minor pest. Knowledge about the biology of A. proletella is limited and some of what is currently understood about its ecology has been inferred from anecdotal evidence. The overall aim of this project is to understand population trends of A. proletella in the most vulnerable crops, Brussels sprout and kale. This includes understanding the key times of population increase and colonisation of new crops. This information can then be used to inform the development of an integrated control strategy using insecticides and other tools, which might include biological control agents and methods of cultural or physical control. Experiments to investigate the vertical and horizontal distribution of flights by A. proletella showed that A. proletella performs mainly low, short distance flights throughout most of the year and it is these flights that are mostly responsible for colonisation of new vulnerable crops, which can be achieved by overwintering females early in the season. Monitoring of field populations on kale has shown that populations of whitefly develop without regulation by predators or parasitoids, with increases in numbers mostly determined by the development of further generations from the initial immigrants to the crop. The size of a population of A. proletella that can be achieved within a crop seems to be governed by the number of generations that can develop before the onset of diapause in September, which prevents further reproduction. A new fungal pathogen, which causes epizootics within the field, has been observed. This killed up to >90% of adult A. proletella. Of all potential natural enemies this pathogen had the largest potential to reduce A. proletella infestations and offers potential for the development of a new method of biological control.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:723130 |
| Date | January 2016 |
| Creators | Collins, Spencer |
| Publisher | University of Warwick |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://wrap.warwick.ac.uk/92514/ |
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