The Diapause of Gypsy Moth, Lymantria dispar (L.) (Lepidoptera: Lymantriidae)

: Lymantria dispar undergoes a prolonged obligatory pharate first instar larval diapause. Little information is available on the endocrine regulation of this diapause. The purpose of the present paper was to obtain information on ecdysteroid titers during the initial, middle, and terminal phases of diapause. We also investigated the effect of exogenous ecdysterone on diapause interruption. Ecdysteroid titers, measured by radioimmunoassay, were higher in diapausing eggs. Furthermore, exogenous ecdysterone did not prevent diapause. Ecdysteroids seem to play a role in the induction and maintenance of the pharate first instar larval diapause, with a drop in the ecdysteroid titer being essential for diapause termination.