Biological control of nematodes: from soil suppression and the search for a silver bullet to synthetic biology

Nematode suppressive soils are a well-documented phenomenon and a whole host of microbes have been implicated. Commercial agrochemical companies are looking for a single silver bullet that will replace nematicides; these must be environmentally benign and also compatible with other crop protection methods. Baker and Cook’s schematic biological interaction model will be applied to crop, nematodes and their natural enemies to contextualise the issues. To date there are no successful biological control agents that can routinely replace nematicides for use as a silver bullet in the field situation. However, molecular biology has revolutionized our understanding of host-parasite interactions from nematode trapping fungi to bacterial wart disease. Various platforms by which bacteria can be engineered are now available and novel biological functions can be added to both Gram-positive and Gram-negative bacteria; some of these platforms will be reviewed. Finally, the question around whether or not these new approaches may offer a way forward for biological control will be presented.