Behavioural observations and neurophysiological responses of cockroaches envenomated with Latrodectus katipo venom.

1. The behaviour of American cockroaches envenomated with Latrodectus katipo venom was correlated with neurophysiological events recorded from an isolated cockroach CNS preparation to which venom was applied. 2. The injection of a venom extract into cockroaches caused convulsions (3 behavioural categories: quivering, jerking and hyperextension) which eventually led to paralysis and death. 3. Changes in the spontaneous activity of nerve 5 (from the metathoracic ganglion) corresponded to the time course of envenomation behaviours. An initial increase in discharge peaked 5-10 min after application and subsequently decreased to become irreversibly blocked.