D3074: Reducing aphids on barley by exploiting beneficial species interactions with rhizobacteria and natural enemies

Aphids reduce agricultural yield and quality by extracting plant nutrients and vectoring diseases. Pesticides, although effective, can damage ecosystems and pest populations are evolving resistance. There is increasing evidence for using soil microbiome manipulation as a pest control strategy. We inoculate barley with beneficial rhizobacteria to reduce aphids by inducing plant defences and recruiting natural enemies such as parasitoid wasps in the field. We present results from full season outdoor pot and glasshouse experiments using rhizobacteria inoculation across different barley varieties to explore aphid and natural enemy colonisation. We saw earlier arrival and more parasitoid wasps on rhizobacteria inoculated barley compared to the control treatment. Aphid suppression was variable between barley varieties and across time, with some inoculated plants even attracting more aphids in the outdoor pot experiment. We investigated this further through controlled aphid choice experiments and chemical analysis of barley leaves. Ongoing work explores effects of rhizobacteria inoculation on plant volatiles in relation to parasitoid behaviour as well as aphid susceptibility to parasitism. Overall, we aim to provide practical solutions for agriculture and food security.