Understanding interactions between biopesticides and partial crop resistance for management of aphid pests of brassica crops

Lead Research Organisation: University of Warwick
Department Name: School of Life Sciences

Abstract

Aphids are important pests of crops and there is a need for new, environmentally sustainable methods for their control. In particular, there is potential for new integrated pest management systems based around biological control methods including resistant crop varieties, biopesticides and natural enemies. The aim of this project is to provide new knowledge on the interaction between partial host plant resistance in brassicas and fungal biopesticides for the control of cabbage aphid Brevicoryne brassicae, an important pest of brassica crops. Our IPM strategy is to use partial varietal resistance to slow down aphid developmental while at the same time enhancing the performance of biocontrol agents. Slower aphid development increases the time for which they are susceptible to entomopathogen infection (e.g. by preventing young instars 'escaping' from fungal spores by moulting). An added benefit is that partial resistance will be under a much lower selection pressure than major gene resistance and should prove more durable. Candidate Brassica accessions for partial resistance, identified through the scientific literature and by RNASeq analysis of a brassica diversity set for JA signalling pathway and camalexin production, will be screened in an infestation study using a B. brassica clone to determine aphid survival and rate of development. Validation for JA / camalexin will be done using rt-PCR. Laboratory bioassays will be used to quantify the effects of selected strains of entomopathogenic fungi (Beauveria, Metarhizium, Lecanicilliu, Isaria) on the survival and longevity of different life stages of B. brassicae feeding on Chinese cabbage B. rapa and a commercial variety of Brussels sprouts B. olereacea (as a baseline). Bioassays will then be done with a subset of fungal strains to determine their virulence to B. brassicae populations feeding on Brassica accessions that show partial aphid resistance. Comparisons will be made with susceptible plant accessions.

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
BB/M01116X/1 01/10/2015 30/09/2023
1897825 Studentship BB/M01116X/1 02/10/2017 30/09/2021 Andrew Gladman
 
Description This project focusses upon developing a novel fully integrated approach for the management of aphid pests in vegetable Brassica crops (broccoli, cauliflower, kale, cabbage, kohl rabi etc). Current field control measures rely heavily upon conventional chemical pesticides however with both aphid development of resistance to these pesticides alongside government driven withdrawal due to health concerns farmers have access to ever fewer options to control aphids in their crop

Thus far this project has successfully identified across numerous Brassica plants a range of resistance to aphids - with those demonstrating the most robust partial resistance limiting aphid populations to approximately a quarter of those populations seen in the most Brassica susceptible plants. Utilising this decrease, we plan to now test whether these differences in populations allow for more effective deployment of biopesticides agaisnt aphids thus demonstrating the combinatory benefits of resistant crop plants with biological pest control approaches.
Exploitation Route While Integrated Pest Management has been a long heralded ideal, truthfully IPM has thus far evaded the majority of outdoor crops. This project provides a useful example of how IPM strategies should be devised and tested and emphasises that for IPM strategies to work, a wealth of information is required around each component of the strategy and how they interact.

The identified resistant lines may further prove useful for breeding programmes.
Sectors Agriculture, Food and Drink,Environment