Development of a novel nuclear DNA marker to identify biotypes A and B of the stone leek leafminer, Liriomyza chinensis (Diptera: Agromyzidae)

The stone leek leafminer Liriomyza chinensis (Kato, 1949) (Diptera: Agromyzidae) is a serious insect pest that invades the Japanese bunching onion (JSAEZ (ed.) 2006). A novel population of L. chinensis, here termed biotype B, has been repeatedly detected in many prefectures in Japan since 2016, which showed larval mine forms different from those of the native L. chinensis populations (biotype A). Though a previous study examined a portion of the mitochondrial cytochrome c oxidase I (mtCOI) sequences of these biotypes and revealed that there is DNA polymorphism between biotypes A and B, their nuclear DNA has not been examined; therefore, hybrid individuals have not been detected. To identify the biotypes of L. chinensis collected around Japan with precision, a novel nuclear DNA marker was established. Moreover, to reveal their phylogenetic relationships, phylogenetic analyses were conducted by comparing the biotype mtCOI and D2 region sequences of the 28S rDNA, which represent useful indexes of phylogenetic differentiation. Based on these analyses, the monophyly of L. chinensis was strongly supported (100% bootstrap support). The nuclear and mitochondrial DNA markers facilitated gathering maternal mitochondrial information and distinguishing hybrid individuals. This approach may help elucidate reproductive interference, which may cause the replacement of biotype A with biotype B.