Bots and agents
Although agents are not in themselves the cause of stigmergy, they are essential components of stigmergic systems.
They usually start off as quite simple, passive constructs, but, as stigmergic systems grow and evolve greater complexity, their agents are likely to become increasingly more sophisticated.
At these times, almost any kind of agent technology can be introduced, so it is necessary for any stigmergic system strategist to keep up to date with what is happening in the agent and bot fields.
Below are two links for starters: