Characterization of Differences between Two Trichogramma Wasps by Molecular Markers

Of the two egg parasitic wasps of the Asian corn borer (Ostrinia furnacalis Guenée) (Lepidoptera: Noctuidae) present in Taiwan, Trichogramma ostriniae Pang & Chen (Hymenoptera: Trichogrammatidae) is the dominant species in corn fields and shows higher parasitism than Trichogramma chilonis Ishii in laboratory studies. Molecular techniques were applied to characterize these two wasps, which are small in size and lack clear morphological differences. Distinct differences in the products of random amplified polymorphic DNA were observed in these two species. The internal noncoding transcribed spacer (ITS) region and the partial products of this region of ribosomal DNA, amplified by polymerase chain reaction (PCR), from these two species varied in length. The sequences of the ITS1 regions of the two wasps shared 86.1% identity. PCR with species-specific primers based on these sequences gave partial ITS1 products of 458 and 322 bp and thus unequivocally differentiated T. ostriniae from T. chilonis.