Bacteria can mobilize nematode-trapping fungi to kill nematodes.

In their natural habitat, bacteria are consumed by bacterivorous nematodes; however, they are not simply passive preys. Here we report a defensive mechanism used by certain bacteria to mobilize nematode-trapping fungi to kill nematodes. These bacteria release urea, which triggers a lifestyle switch in the fungus Arthrobotrys oligospora from saprophytic to nematode-predatory form; this predacious form is characterized by formation of specialized cellular structures or 'traps'.