Infestation of Cycas revoluta by the exotic scale insect Aulacaspis yasumatsui and its chemical control in Okinawa Island, Japan

Abstract

Following an earlier report of an infestation in Amami Island, Japan, the exotic scale insect Aulacaspis yasumatsui was confirmed to attack Cycas revoluta in Okinawa Island, Japan. Plants damaged by A. yasumatsui were localized in two adjacent villages in the northern part of Okinawa Island, far from the island's main port facilities. The damaged area was localized compared with the earlier infestation in Amami Island. Interviews with a resident and a facility manager revealed that damage had become visible in 2020 and 2021. Two months after the application of an insecticide spray, there was no sign of new leaves being attacked and no abnormalities were visible in all previously attacked plants. Chemical control and the removal of damaged leaves are labor-intensive procedures; therefore, control methods that are easier to undertake need to be established.