Improving biological control in protected crops

Thomas, A. (2020) Improving biological control in protected crops. Doctoral thesis, Harper Adams University.

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Management of the leafhopper Hauptidia maroccanais inadequate. Despite not being a regular pest in glasshouses, H.maroccanais capable of significant damage. Current conrol methods rely on one chemical agent(Indoxacarb) and a putative predator. In the face of widespread chemical resistance and unreliability of generalist predators, the risk to growers under these conditions is increased. Part of the problem facing growers is that only very basic information about this pest is known, with few studies on the ecological interactions that will be vital for suffifcient control. It is these knowledge gaps that this thesis addresses. A summary literature review introduces the main topics of study and examines the failure of a previously attempted biological control agent. Chapter 2 builds on evidence from similar species and looks at improving trapping of the pest in glasshouses. Non-yellow traps are tested for efficacy and selectivity under laboratory conditions, and indicate that there is scope for improvement in this area. The visual ecology of this pest is examined again in Chapter 4 where the use of LED technology to increase the visual signal of traps is examined. The results of which again indicate that there is more complexity to the visual cues evaluated by H.maroccanathan the consensus implies. The importance of plant volatiles to herbivores is well studied. For H.maroccanahowever, much is not known. Of particular importance is the ability of this pest to detect and respond to the volatile blends released by plants under attack by conspecifics. Growers have reported that H.maroccanaforms hotspots within crops. Whether this is due to aggregation or a lack of migration is unknown. Information from experiments here suggests that it is largely due to lack of emigration rather than aggregative behaviours. The use of the generalist predator Macrolophuscaliginosus for control of leafhopper is critically examined and tested under laboratory conditions. The overall picture is mixed with predation of leafhopper nymphs approaching levels of consumption seen for other pests, but predation on adults being almost zero. Furthermore, the response of Macrolophusto plant volatiles from infested plants was mixed, which may indicate that under a more complex environment, the ability of this predator to locate H.maroccanais reduced. In the final chapter the project is reviewed as a whole against the objectives and summarised

Item Type: Thesis (Doctoral)
Divisions: Agriculture and Environment (from 1.08.20)
Depositing User: Ms Kath Osborn
Date Deposited: 05 Mar 2021 10:05
Last Modified: 22 Jul 2021 11:30

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