Abstract
In order to clarify whether or not Ixodes persulcatus Schulze nymphs reared in a long-day photoperiod before and after molting enter behavioural diapause by exposure to short-day photoperiods, their feeding activity was observed using mice at 24℃ under four photoperiodic conditions (16L-8D, 12L-12D, 11L-13D, and 10L-14D). The percentage of engorged nymphs reared at 24℃ under a 16L-8D photoperiod before and after molting was very high (74%) when they were kept under the same conditions 7-8 months after molting. However, the engorgement percentage of the nymphs became lower as the exposed day-length shortened. These results suggest that the nymphs reared in a long-day photoperiod before and after molting enter behavioural diapause by exposure to short-day photoperiods. Judging from the percentage of engorgement, however, the proportion of occurrence in the behavioural diapause appears to be low. The low occurrence of behavioural diapause may be due to the age of the nymphs.
