5.10.3. Polyembryony

This form of asexual reproduction involves the production of two or more embryos from one egg by subdivision (fission). It is restricted predominantly to parasitic insects; it occurs in at least one strepsipteran and representatives of four wasp families, especially the Encyrtidae.

It appears to have arisen independently within each wasp family. In these parasitic wasps, the number of larvae produced from a single egg varies in different genera but is influenced by the size of the host, with from fewer than 10 to several hundred, and in Copidosoma (Encyrtidae) up to 3000 embryos, arising from one small, yolkless egg. Nutrition for a large number of developing embryos obviously cannot be supplied by the original egg and is acquired from the host’s hemolymph through a specialized enveloping membrane called the trophamnion. Typically, the embryos develop into larvae when the host molts to its final instar, and these larvae consume the host insect before pupating and emerging as adult wasps.

Chapter 5