ABSTRACT
Parasitic or parasitoid Hymenoptera are widely used for biological control; indeed, over 360 species representing 18 families have been used in control programs. This chapter discusses various features of parasitoid genetics which arise as a consequence of haplodiploidy and are relevant to biological control. Hymenoptera have significantly lower levels of allozyme variation than comparable diplodiploid insects, and this is predicted as a consequence of haplodiploidy. However, the observed sex ratio in natural or laboratory populations of parasitoid Hymenoptera is often female or male biased and is the result of either environmental or genetic causes. Although, at a phenomenological level, sex is determined by ploidy, a genetic mechanism of sex determination has been demonstrated in some Hymenoptera. The chapter discusses the frequency of diploid males expected in populations of parasitoids and Hymenoptera in general and some of the problems involved in the estimation and interpretation of this.
