The monograph focuses on the distribution of molecular variations in a braconid, Cotesia plutellae (Kurdj.), a parasitoid of the diamondback moth (Plutella xylostella L.). It describes the diversity of Cotesia species assessed by AFLP fingerprinting and sequencing of 16S, ND1, COI, ITS2 and FtsZ gene regions. This monograph will be helpful in insect diversity studies and decision-making on the use of potential strains for biocontrol programmes, and will also help researchers and beginners in molecular entomology at graduate and postgraduate levels.