Inhibition of insect development by simultaneous action of prothoracic gland hormone and juvenile hormone

Injections of large amounts (around 20 μg) of ecdysterone and of Cecropia C₁₇-juvenile hormone or its bio-analogue 6,7-epoxygeranyl 3,4-methylendioxyphenyl ether into a pupa of Tenebrio molitor may inhibit the apolysis and cuticle secretion. Some of the treated insects secrete a new cuticle only locally, others do not even undergo apolysis although they survive until the controls ecdyse as adults. The development of internal organs is also hindered. These results are tentatively explained in terms of a mutually antagonistic action of the two hormones on nucleic acid synthesis.