A CRICKET (GRYLLUS-BIMACULATUS) NEUROPEPTIDE INDUCES DARK COLOR IN THE LOCUST, LOCUSTA-MIGRATORIA

The dark-colour inducing effect of various parts of the nervous system and the corpora cardiaca of crickets (Gryllus bimaculatus) was examin ed by implanting these organs into albino nymphs of the locust, Locust a migratoria, The corpora cardiaca were most effective, When implanted at the beginning of the 4th instar, albino locusts developed a unifor mly blackish body colour after ecdysis to the 5th instar, Black patter ns with an orange background colour, resembling normal gregarious locu st nymphs, were induced after implantation at the middle of the 4th in star, Implantation late in the 4th instar induced a reddish body colou r without black patterns, Methanol extracts of the cricket corpora car diaca induced a dark colour in albino locusts when the extracts were d ried, mixed with soybean oil and injected. Water extracts were much le ss effective, and the hexane extracts had no activity, Activity of the methanol extracts was destroyed with a proteinase. Ore the other hand , boiling or exposure to a preheated proteinase did not destroy the ac tivity, These results indicate that the dark-colour inducing factor in the cricket corpora cardiaca is a heat-stable neuropeptide(s), The dr ied methanol extracts of cricket corpora cardiaca did not influence th e body colour of conspecific individuals.