Molecular Identification of Genotypes of Pilophorus typicus (Heteroptera : Miridae) in Japan using PCR-RFLP Analysis of Mitochondrial DNA

Pilophorus typicus (Heteroptera: Miridae) is a candidate insect for biological control against agricultural pests such as aphids, whiteflies, and spider mites. This species has two genotypes in Japan, i.e., the northern and southern types, but it is difficult to differentiate them because of few morphological characters separating them. Artificial migration across the distribution range of each genotype may incur ecological and genetic risks. To conduct a prompt identification of the two genotypes, we developed the method of PCR-RFLP using the cytochrome oxidase subunit I (COI) region on mitochondrial DNA. The PCR product of the southern type yielded two DNA bands by the action of the restriction enzyme of Psi I, whereas that of the northern type gave only a single band on electrophoresis. Moreover, the PCR-RFLP using samples from many localities revealed that the restriction site of Psi I is well conserved within each type. These results suggest that the PCR-RFLP of the COI region provides the accurate and easy discrimination of the two genotypes of P. typicus.