NIAB EMR: M. Fountain & C. Whitfield
NRI, University of Greenwich: Daniel Bray
The Spotted Wing Drosophila (D. suzukii) is serious economic pest threatening the sustainability of the UK horticulture industry. First detected in the UK and in 2012 and becoming established within a year, D. suzukii damages stone and soft fruit by ovipositing in ripening fruit. Current D. suzukii control strategies rely on multiple sprays of (often broad spectrum) insecticides. This is counter to DEFRA and European Commission policies to minimize pesticide use, and can also impact on beneficial, non-target organisms in crops. Research is therefore urgently needed to develop a comprehensive control strategy, less reliant on conventional insecticides, to protect UK growers from the damage which can be caused by D. suzukii.
The research in this PhD will link to and build upon a number of ongoing research projects at NIAB EMR and NRI investigating novel control methods for use against D. suzukii. It will combine previous approaches to create an innovative push pull strategy to repel D. suzukii away from crops, while attracting them into traps where they can be killed.
Approaches and work packages
WP1. Literature review, training and development of laboratory methods used throughout the project (Oct 2017 April 2018)
Through this WP the student will develop skills and techniques to be applied throughout the project. This will include setting up and maintaining cultures of D. suzukii and conducting GC-EAG (gas chromatograph linked electroantennograms) and GC-EPG (electropalpograms) to identity naturally occurring chemicals which elicit responses in the insect olfactory system. Training will be provided in formulating these chemicals into blends, and in conducting subsequent laboratory bioassays and field trials to test and develop blends as attractants and repellents. Broader skills training centred on career development will be provided by the PhD programme of the University of Greenwich.
WP2. Development of Pull components (behaviourally attractive compounds) (Feb 2018 Dec 2018)
This WP will focus on optimising baits for D. suzukii using attractive compounds identified in ongoing work at NRI and NIAB EMR. New bait combinations will be tested first in the laboratory with successful blends trialled in commercial polytunnels.
Behavioural studies in the laboratory and field will address key variables critical to developing attractants as successful monitoring and control tools. These will include optimisation of visual characteristics of the trap in which the bait is deployed, comparing different colours, sizes and shapes. Field studies using marking techniques will determine the distance over which D. suzukii are attracted to the trap, with further trials to optimize positioning of traps (distance and vertical height), and timing of deployment (likely to be from early spring) for maximum impact on pest populations.
WP3. Development of Push components (behaviourally repellent compounds) (Jan 2019 Dec 2019)
Work conducted in this WP will optimise blends and release rates of compounds repellent to D. suzukii through wind tunnel bioassays. Field trials will be carried out to determine the distance at which the repellent is behaviourally active, as well as to optimize test formulations and determine the most effective timing of deployment (likely to be from early spring) and time interval between applications to protect crops.
WP4. Field trials to develop a Push-Pull system (March 2020 July 2020)
In the final field season the results of WP 2 and WP 3 will be deployed together in a Push-Pull system. Field trials will be performed in commercial polytunnels to investigate the effectiveness of attract and kill in combination with repellents for control of D. suzukii. The trial will study the effect of the Push-Pull system on the target species and non-target species including both beneficial insect and pests. A limited economic assessment will be carried out to compare the economic sustainability of the Push-Pull system to conventional control measures.
This research will provide the basis for an IPM control strategy targeting D. suzukii suitable for commercial growers of stone and soft fruit. The research will optimise attractants and repellents and their deployment in order to provide the control. The integration of several control methods to form a Push-Pull system is a novel idea for this pest and will lead to a significant reduction in the use of chemical pesticides. Improved understanding of the insects olfactory sense and searching behaviour will provide the scientific basis for the development of the Push-Pull system.
The student will design and implement laboratory and field trials developing their statistical analysis skills to accomplish this. Throughout the PhD they will learn entomological techniques in insect behaviour, olfaction, and chemical ecology. The work will be closely connected to commercial growers and is a response to a need for an IPM based control strategy in the UK for this hugely significant pest.