Identification of agromyzid flies infesting six native orchid species in Chiba Prefecture, Japan, and their damage assessment

Abstract

To identify the agromyzid species and to compare the degree of damage among different orchid species, we surveyed infestation by agromyzids on six native orchids in Sammu, Chiba, Japan. To obtain fly specimens, flowers and fruits of the six orchid species were collected from the field. Adult flies collected from the fruits of Cypripedium japonicum Thunb. were morphologically identified as Japanagromyza tokunagai (Sasakawa). Then flies collected from the six orchid species were molecularly identified by sequencing the mitochondrial DNA cytochrome oxidase subunit I (COI) gene. In addition, we sequenced the flies collected from March to July to confirm possible seasonal changes in agromyzid species composition. As a result, they were all regarded as J. tokunagai. Further, the developmental stage of infesting fly was investigated every two weeks from May to July 2016 in three of the six orchid species. The infestation rates of Cephalanthera falcata (Thunb.) Blume and C. japonicum were extremely high in this site, and the control of J. tokunagai will be required for the conservation of these orchids.