Teratocytes as a Source of Juvenile Hormone Activity in a Parasitoid-Host Relationship

PARASITOIDS of the hymenopterous family Braconidae liberate extra-embryonic cells within their host at the time of hatching from the egg1. These cells, referred to as teratocytes2 or giant cells3, 4, maintain an independent existence in the host's haemocoel, increasing in size from 14 m in diameter at egg hatch to over 300 sm in diameter in 10-12 d. Teratocytes may serve as a food source for the developing parasitoid larvae6. Vinson5 has demonstrated that the growth and development of larvae receiving only teratocytes were very similar to normally parasitised larvae; in most cases, the larvae pupated abnormally and the effects resembled those which can be produced by the administration of juvenile hormone. Here we show for the first time that ether extracts of teratocytes of Cardiochiles nigriceps Viereck in its host Heliothis virescens (F.) do indeed exert juvenile hormone activity in the galleria wax test.