THE DROP-OFF RHYTHM OF AMBLYOMMA-TRIGUTTATUM-TRIGUTTATUM KOCH (ACARI,IXODIDAE) FROM LABORATORY HOSTS

The pattern of drop-off of Amblyomma triguttatum triguttatum Koch was studied by infesting rabbits and rats with larvae and nymphs, and calv es with adult ticks maintained at a daily photoperiodic regime of 12 h light 12 h dark. Additional information was obtained by infesting rab bits with nymphs in or out of phase with the photoperiodic regime expe rienced by the host. The great majority of ticks detached during the p hotophase: only 9.7% of larvae and 11.3% of nymphs fed on rats, 12.0% of larvae and 15.8% of nymphs fed on rabbits, respectively, and 10.0% of female ticks detached during the scotophase. The rhythm was not sub stantially altered by feeding nymphs in or out of phase with the photo periodic regime of the host. The drop-off rhythm seemed to be coupled with endogenous rhythms of the host.