EMBRYONIC MORPHOLOGY AND GROWTH OF THE POLYEMBRYONIC PARASITOID COPIDOSOMA-FLORIDANUM (ASHMEAD) (HYMENOPTERA, ENCYRTIDAE)

The morphology and growth of the polyembryonic parasitoid Copidosoma floridanum (Ashmead) (Hymenoptera : Encyrtidae) was investigated in relation to the development of its host, Trichoplusia ni (Hübner) (Lepidoptera : Noctuidae). During the host egg stage, the C. floridanum egg exhibited holoblastic cleavage and formed a primary morula enveloped by a membrane and the chorion. The morula ruptured free of the chorion prior to hatching of the host egg. During the T. ni 1st-through 4th larval stadia, the primary morula proliferated to form secondary morulae or a polymorula. Morulae varied greatly in size during this period of proliferation. By the 2nd day of the T. ni 4th stadium, embryos were uniform in size and proliferation had ceased. The embryos then increased in size exponentially, and synchronous morphogenesis began on the 1st-day of the T. ni 5th-stadium. Initiation of morphogenesis was marked by the formation of a ventral fold. Pharate 1st-instar parasitoid larvae were present on the 2nd day of the T. ni 5th-stadium. Larvae emerged on the 3rd day of the T. ni 5th-stadium. Embryonic cells did not change in size during development, but the number of cells per embryo increased exponentially during morphogenesis. © 1990.