Actually, I am currently working on a video of zapping worms in a water based environment using the MY. The worms seem unaffected until the zapper switches to s specific frequency, upon which they react almost immediately, within a few seconds, and most are dead by the time it changes to the next frequency. In other modes, that do not have a frequency that they are affected by they survive for a couple of hours.
They also survive for a couple of hours in contact with the electrodes in place but the zapper not turned on.