Levels of ecdysteroids in diapause and non-diapause eggs of the Australian plague locust, Chortoicetes terminifera (Walker)

The levels of ecdysteroids during embryogenesis in Chortoicetes terminifera were measured by radioimmunoassay. Soon after laying, eggs laid by females reared under non-diapause conditions contained three times as much as those laid by females reared under diapause inducing conditions. In eggs incubated at 32°C which did not enter diapause there was a sharp rise in ecdysteroid levels which coincided with the formation of the first-instar cuticle, but this did not occur in eggs incubated at 20°C even though they developed and hatched normally. Comparisons are made with previous results in other locust species and the possible role of ecdysteroids in embryonic diapause is discussed.