CUTICULOGENESIS AND ECDYSTEROIDS IN LABID URA-RIPARIA EMBRYOS (INSECTA, DERMAPTERA)

In Labidura riparia, embryonic development lasts 10 days at 27 degrees C and 70% RH. A germ band is perceptible on the 3rd day. It becomes s egmented on the 4th day. Blastokinesis is achieved on the 7th day at t he beginning of the dorsal closure of the embryo. A first rudimentary cuticle is secreted by the germ band before the 5th day. A second cuti cle appears on the 7th day. This cuticle is typical and will cover the first instar larvae. The apolysis of this second cuticle coincides wi th hatching. Two ecdysteroid peaks are observed during embryonic devel opment. The first peak arises on day 8 and the second one at hatching. There is therefore a correlation between the ecdysteroid titre increa se and the synthesis of the second cuticle as also its apolysis.