This project will underpin the development of a ‘slow down / speed up’ integrated pest management (IPM) system for aphid pests of field crops that combines plant breeding and biological control, focusing on the peach potato aphid, Myzus persicae. Our approach involves slowing down the growth rate of pests while speeding up the performance of their natural enemies. We are investigating the hypothesis that Brassica genotypes with partial resistance that slows down aphid development makes the pest more susceptible to biological control agents including biopesticides and parasitoids. Studies have shown that defence responses in Arabidopsis against M. persicae are based around phytohormone signalling pathways and the phytoalexin camalexin. Expression analysis of gene homologues in Brassica accessions indicates that identifying partial resistance to M. persicae in Brassica crop breeding material is highly likely. The project explores how this partial host-plant resistance can be combined with biocontrol agents. The research has 5 components: (1) Candidate Brassica genotypes with potential resistance are be evaluated using a combination of transciptome analysis and phenotyping experiments, (2) The molecular basis for partial resistance to M. persicae are being investigated, informed by experiments that quantify aphid feeding and development on Brassica genotype breeding lines with aphid resistance markers, (3) Fungal biopesticides are being evaluated against M. persicae on resistant brassica genotypes and research are being done to quantify how biopesticide performance is affected by the fluctuating environmental conditions occurring in field crops, (4) The responses of parasitoids to volatiles from aphid-infested Brassica genotypes are being quantified and the role of cis-jasmone in parasitoid attraction is being elucidated, (5) Field experiments are then being done to measure aphid control on different Brassica genotypes following treatment with fungal biopesticides, parasitoids and cis-jasmone.