2025 Volume 107 Issue 4 Pages 118-122
Mass oak mortality due to Japanese oak wilt disease caused by the ambrosia beetle vector Platypus quercivorus has rapidly increased in the Kanto Plain since 2020. However, knowledge regarding the seasonal prevalence of beetles is lacking for countermeasure implementation. This study aimed to determine the seasonal prevalence of beetles in a mass-mortality forest in Ashikaga, Tochigi Prefecture, Japan. We used flight interception traps to capture flying adult beetles set in the forest and emergence traps to capture adult beetles emerging from their holes in the living stems of the two oak species during March and December 2022. We found that adult beetles flew between 13th of May and the end of November, and that the adult beetles started to emerge continually and abundantly from the holes on 24th of June and were almost complete in September. These results indicate that the adult beetles started to fly earlier and emerged later than our estimated date of first occurrence (26 May) based on the measured temperature. These results also show that a moderate number of flying adult beetles continued to be captured after September, whereas the emergence of adult beetles almost ended from the holes, implying their partial bivoltinism.
