Inherited Male-Producing Factor in an Insect That Produces Its Males from Unfertilized Eggs.

An inherited factor causing the normal sex ratio of 92 percent females to drop to about 5 percent has been produced by selective breeding in a laboratory strain of the arrhenotokous parasitic wasp Dahlbominus fuliginosus (Nees) (Hymenoptera, Eulophidae). The factor is known to be of genetic origin and is sex-limited, being transmitted by females to their sons. Its effect on the sex ratio is constant and not influenced by the female parent, the host, or the environment.