EFFECTS OF ECDYSONES ON DIAPAUSE IN EUROPEAN CORN BORER OSTRINIA NUBILALIS

Ecdysone and 20-hydroxyecdysone were shown to induce apolysis in diapausing European corn borers when the hormone was injected into the haemocoel in very high dosages. The sensitivity to ecdysones could be increased by treating the insects with ammonium acetate or by partial dehydration followed by hydration at the time of hormone treatment. Ecdysone was effective for only a few hours after injection. No evidence was obtained to suggest that experimentally administered ecdysone accelerated normal development leading to pupation. The apolytic response appeared to be pathological, in that only moribund larval-pupal mosaics were obtained. In most, larval characteristics predominated, and none of the responding insects were able to complete the moult. © 1969.