THE PRECOCIOUS COMMITMENT OF WING ANLAGEN IN TENEBRIO-MOLITOR REVEALED BY THE ADDITION OF 20-HYDROXYECDYSONE

An injection of 20-hydroxyecdysone (10 mug per animal) 6-13 days after the moult of the last larval instar of Tenebrio molitor induces the d evelopment of prothetelic larvae and larval-pupal intermediates. The s tate of larval-pupal switchover, or commitment, is only disclosed at t he time of injection of the moulting hormone. Prothetelic A and B larv ae, with small and medium sized wing Anlagen, undergo another larval o r pupal instar. Prothetelic C larvae with bigger Anlagen are unable to moult, but the adult programme is expressed. Ecdysed larval-pupal int ermediates give more or less perfect adults, while unecdysed mealworms , imprisoned in their larval cuticle; also expressed the adult program me. The commitment of Tenebrio is not a global switchover because a si gnificant asynchronisation is noted between the development Of organs considered. Animal crowding induces a delay in the appearance of wing Anlagen.