Monitoring the gravitational reflex of the ectoparasitic mite Varroa destructor: A novel bioassay for assessing toxic effects of acaricides

► Varroa demonstrates a constant gravitational reflex when fixed dorsal side-down. ► The rhythmic sternum movement is maintained for over 20 h. ► The parameters of the gravitational reflex can be measured accurately. ► The gravitational reflex was used as an indication of the vitality of Varroa. ► The toxic effect of amitraz, formic acid, thymol, and Apiguard® were tested.