ANALYSIS OF POSTEMBRYONIC DEVELOPMENT OF LOCOMOTOR-ACTIVITY RHYTHM BYCORPORA ALLATA IMPLANTATION IN THE CRICKET GRYLLUS-BIMACULATUS

1. Male crickets Gryllus bimaculatus show a drastic change in circadia n rhythm from nymphal diurnality to adult nocturnality, in association with an increase in activity level several days after the imaginal mo ult. 2. The corpora allata implantation into male 7th or 8th instar ny mphs produced supernumerary instar nymphs in about 30% of the implante d animals, but did not affected the normal development in the remainin g animals. 3. The majority of the supernumerary instar nymphs were diu rnal and sexually inactive, although their internal reproductive organ s appeared to be fully mature. 4. The supernumerary instar nymphs beca me nocturnal with an increase in activity level several days after the imaginal (9th) moult. 5. The roles of the nervous system in the regul ation of the rhythm reversal are discussed.