Manipulation of host behavior by parasitic insects and insect parasites

Reviews cases in which parasites alter host behaviour, with particular attention to the jewel wasp, which injects venom directly into specific regions of a cockroach’s brain, and examines what is established about the neural mechanisms in each system.

Studied in

Hymenoptera, Insecta

Sample size

review of host-manipulation systems

Behavioural manipulation is achieved by several distinct routes — direct injection into the nervous system, secretion of neuroactive compounds, and alteration of host physiology — and the neural mechanism is well characterised in very few systems. The jewel wasp is the clearest, because the venom is delivered to identified brain regions and the resulting behavioural change can be mapped onto them.

• A review; mechanisms are established in a handful of systems and inferred in most.
• Insect-focused, and manipulation in vertebrate hosts is treated only briefly.

• Parasitism and predation

  A parasitoid sits exactly between the two categories: it consumes a single host and kills it, like a predator, but slowly and from inside, like a parasite. That is why it needed its own word.

• Parasitism and predation

  The jewel wasp genuinely does work on a brain: it stings venom into specific regions of a cockroach’s, and the effect follows. That is the well-understood case — and it is not what the famous zombie fungus does.