ABSTRACT
Sex determination is the process by which the gender of a bisexual organism becomes fixed, so that the individual progeny develops either as a son or a daughter. The sex of an insect is almost always determined genetically. Hermaphroditism, in the sense of the same genotype producing functional male and female organs in the same individual, seldom occurs in insects; it seems to have evolved only once, in one genus of scale insects. It is characteristic of multiple sex chromosome systems formed by dissociation are much smaller than the original X, and that there is no accompanying change in the number of autosomes. The Coleoptera show a great diversity of sex chromosome systems, although the underlying genetics of sex determination may well be far less variable, and is likely to be based on a recessive-X mechanism, except where male haploidy has evolved.
