Lepidopteran sex determination: a cascade of surprises.

Sex determination is a developmental pathway that fixes the sexual fate (male or female) of an individual at early stages of embryonic development. This pathway is ideally suited for evolutionary studies given the astoundingly diverse mechanisms found in the animal kingdom. In particular, insects use multiple different cues to specify the sexual fate of an individual. In this review, we focus on genes and genetic interactions involved in the sex determination of insect species belonging to the order Lepidoptera. Unique features of the lepidopteran sex determination system are discussed.