Molecular identification of Aphidius transcaspicus (Hymenoptera: Braconidae: Aphidiinae), a closely associated species of Aphidius colemani, in Korea

Aphidius colemani (Braconidae: Aphidiinae) is an endoparasitoid and one of the most commercially used parasitoids for the control of various pest aphids. However, species identification of A. colemani is difficult because of the high degree of morphological similarity with closely associated species, such as A. transcaspicus and A. platensis. Recently, we identified a large-scale emergence of parasitoids from mummies of Rhopalosiphum maidis on barley banker plants in Yecheon County, Korea. The morphological characteristics of the forewing, petiole, and antenna indicated that our specimen is A. transcaspicus. The partial nucleotide sequence analysis of the mitochondrial cytochrome oxidase subunit I (COI) gene showed that it is 100% identical to Japanese specimens and 1.69% variable to Greek specimens. Analysis of the phylogenetic tree, haplotypes, and amino acid sequence of the COI gene, as well as the internal transcribed spacer 2 (ITS2) of the nuclear ribosomal DNA region, indicated that A. transcaspicus is closer to A. platensis than A. colemani, and Korean and Japanese populations were mostly diversified groups at the intraspecific level. This study provides important information to elucidate the genetic variation in A. transcaspicus and the relationships between closely related species within the A. colemani group.