Host–Polyembryonic Parasitoid Interactions

Abstract

Entry into the host body is a prerequisite for successful completion of the endoparasitoid life cycle. Most endoparasitoids achieve this by laying eggs directly inside the body cavity of the host. In most braconid and ichneumonid parasitoids, the ovipositor is inserted within the host hemocoel to lay eggs, and the hatched larvae grow and develop rapidly inside the host hemolymph as host development advances and finally consume the host tissues, leading to death of the host, which is why parasitic wasps are usually referred to as “parasitoids.” By contrast, egg–larval endoparasitoids, such as those in the genus Ascogaster (family Braconidae), lay their eggs inside the host embryo or alternatively in the yolk of the host egg, following which the newly hatched larvae enter the host embryo. However, the polyembryonic egg–larval endoparasitoid Copidosoma floridanum cannot employ this strategy due to its prolonged morula stage, so this species has evolved a novel approach for entering the host body that involves tissue-compatible invasion by the motile morula.