Inter- and Intra-Specific Differentiation of Trichogramma (Hymenoptera: Trichogrammatidae) Species Using PCR–RFLP Targeting COI

The identification of Trichogramma (Hymenoptera: Trichogrammatidae) species is problematic due to their small size and lack of distinct morphological characters. In this study, we combined morphological characters of the male genitalia and molecular methods using the mitochondrial cytochrome oxidase I (COI) gene as a molecular marker to identify eight species from 16 geographic populations: T. evanescens Westwood, T. cacoeciae Marchal, T. ostriniae Pang et Chen, T. chilonis Ishii, T. japonicum Ashmead, T. brassicae Bezdenko, T. bilingensis He et Pang, and T. dendrolimi Matsumura. We developed a polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) method targeting the mitochondrial COI to distinguish the eight Trichogramma species using three restriction enzymes. We further analyzed 109 COI fragments from 18 Trichogramma species and found that the PCR–RFLP method could distinguish both intra- and inter-specific genetic variation among most of the species using four additional restriction enzymes.