Underestimated mitochondrial diversity in gypsy moth Lymantria dispar from Asia

Abstract

The gypsy moth Lymantria dispar (L.) (Erebidae) is one of the most important agricultural and forest insect pests. It currently includes three subspecies: Lymantria dispar dispar (L.), Lymantria dispar asiatica Vnukovskij and Lymantria dispar japonica (Motschulsky). The first subspecies is known as the European gypsy moth (EGM), whereas the latter two are collectively referred to as the Asian gypsy moth (AGM). Asian gypsy moth possesses traits that include a strong female flight capability and broader larval host range, which make it a more threatening pest than EGM when invading new areas. To better understand the genetic structure within AGM and in particular among Chinese populations, we reconstructed a mitochondrial gene tree based on four mitochondrial protein-coding genes (ND2, ND6, ATP6 and ATP8) from 17 Chinese locations and 21 locations from other countries. None of the three subspecies of gypsy moth is recovered as monophyletic on the mitochondrial gene tree, likely as a result of human-mediated transportation and a high level of cryptic genetic diversity. Chinese populations are split into four mitochondrial clusters. Surprisingly, China I is nested within EGM and China II is the sister group of sampled EGM. China III grouped with samples from South Korea and the Russian Far East to represent the typical L. d. asiatica. China IV formed a sister relationship with the former group. The results of the present study confirm that the recently discovered genotype from the Black Sea-Caspian region consists of an independent mitochondrial genetic lineage from other subspecies.