Disclosed is a pest control agent in the form of a suspension, which exhibits excellent dispersion stability for a long time without forming a hard cake due to settling and separation of solid particles or without losing fluidity due to gelation even when a cationic pest control active ingredient andor an acid is used. Contact element has with four receptacles each designed to connect a conductor. An actuating element is positioned lying radially inwardly relative to a flow channel, between the rotor of the first turbine and a stator of the second turbine.