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Aspects of the biology and ecology of saddle gall midge ( Haplodiplosis marginata )

Rowley, C. (2017) Aspects of the biology and ecology of saddle gall midge ( Haplodiplosis marginata ). Doctoral thesis, Harper Adams University.

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Abstract

The sporadic nature of saddle gall midge (Haplodiplosis marginata) has meant that research into this pest has been, much like the outbreaks, patchy and intermittent. A lack of long term data has so far hampered attempts to develop a cohesive strategy towards the management of this pest. This thesis begins with a review of the existing literature on H. marginata, drawing together information from past studies done over many decades in a number of countries across Europe. Some of this information was previously unavailable in electronic format or required translation making the consolidation of these studies an important part of increasing the availability of current H. marginata knowledge and enabling the identification of research gaps. One example is the lack of information surrounding the developmental biology of H. marginata which is addressed in Chapter 2. Here, the effects of soil temperatures and rainfall events on H. marginata development are studied as a means of forecasting the adult emergence. This has a resulted in the development of degree day-based models to predict H. marginata phenology. Rainfall events followed by an accumulation of 512DD above 0°C can be used to predict peaks in H. marginata adult emergence and cumulative percentage emergence can be modelled using a probit-linked GLM or a bimodal function which can be used to predict the start of, or peaks in, H. marginata emergence as an early warning system for farmers. Chapters 3 and 4 further improve on current options for monitoring by investigating the chemical ecology of H. marginata . Electroantennography coupled with gas chromatography is used to confirm the male response to the female sex pheromone . Field experiments are used determine the optimum formulation for a pheromone lure as 0.5mg (R)-2 nonyl butyrate from a polyethylene vial dispenser This lure is then tested in further situations to define the optimal trap position as being placed at the height of the wheat ear, 20m into the crop with at least 20m between traps. Such experiments give further insight into behavioural aspects of this insect as well as providing practical monitoring solutions for farmers. The natural enemies of H. marginata are another understudied area of research which Chapter 5 attempts to improve upon through the development of a PCR - based assay for gut analysis of arthropod predators. Use of this assay in the field demonstrates the potential for further research in this area through the identification of four carabid species that naturally predate on H. marginata : Nebria brevicollis , Poecilus versicolor , Harpalus rufipes and Loricera pilicornis Finally, a summary chapter suggests how this thesis can be used in further research towards integrated pest management solutions for this insect and places this work into the wider context of a dynamic agricultural environment

Item Type: Thesis (Doctoral)
Divisions: Crop and Environment Sciences
Depositing User: Ms Kath Osborn
Date Deposited: 11 Oct 2018 18:13
Last Modified: 11 Oct 2018 18:25
URI: http://hau.collections.crest.ac.uk/id/eprint/17338

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