The overuse of insecticides has led to huge impacts on the environment and human health, including contaminated drinking water, declines in non-target organisms like birds, fish and honey bees and has been linked to various cancers in humans. Therefore, restrictions on their use are tightening and a need to develop safe and effective alternatives has emerged. One promising alternative is utilizing and developing the root microbiome which can enhance the plant’s defence system. This project aims to test whether recently identified differences in the root microbiomes of modern and heritage wheat varieties results in a difference in resistance to herbivores and how climate may impact these results. This will be achieved in three stages. First, by looking at the functional ability of these microorganisms to produce phytohormones used in plant defences and comparing between modern and heritage wheat varieties. Second, these results will be validated in a glasshouse experiment that directly tests the impact of herbivores on this interaction between root microbiomes and plant defences. Third, the project will use a latitudinal gradient to test the impact of climate on this interaction. The results from this project will lead to a development in microbial based alternatives for controlling insect herbivores that are effective, safe and sustainable to use into the future.