2021 Volume 24 Issue 3 Pages 55-63
An agromyzid, Japanagromyza tokunagai (Sasakawa, 1953) (Diptera: Agromyzidae), seriously damages wild orchids in Japan. The larvae feed on the orchid fruits and flower stalks and prevent seed productions. Understanding the fly infestation can be important in conserving, especially, threatened orchid species, but information of the host plant range and distribution of J. tokunagai are still limited. In this study, we investigated fly infestations in 42 orchid species of 21 genera in Hokkaido to Okinawa Prefectures. The infestations of J. tokunagai were observed in 25 orchid species belonging to 13 genera, eleven species of which were newly found as the host plants of J. tokunagai and included three new host plant genera. The infestations were observed in Hokkaido Prefecture and Iriomote Is., Okinawa Prefecture, showing that J. tokunagai is distributed throughout Japan from Hokkaido to Okinawa Prefectures. Our study also revealed that the infestation rates were varied among orchid species, some of which were highly infested at multiple areas. Furthermore, the rates were lower in Hokkaido Prefecture than other areas, indicating that population density of J. tokunagai may be low in the northernmost limit of their distribution.
