Flight Characteristics of Bactrocera dorsalis Associated with Long-Distance Migration

Recently, individuals of the oriental fruit fly and its relatives (Bactrocera dorsalis complex)-previously eradicated in Japan-have occasionally been captured in surveillance traps in the Kyushu District of western Japan, suggesting possible overseas migration. However, as this species generally is not considered capable of long-distance flight, its potential for overseas migration remains largely unexplored. Moreover, this emerging situation in East Asia poses an increasing risk to agricultural industries, highlighting the need to develop a migration prediction model to provide early warnings of their arrival, for which understanding the species' flight characteristics is essential. In this study, flight experiments were conducted using young first-generation adults that emerged from larvae collected in Taiwan. Outdoor observations revealed that B. dorsalis actively initiates flight around 10:00 and sunset. Flight mill experiments under varying temperature conditions indicated that flight activity ceased at temperatures between 16.2 and 16.5 °C. Furthermore, a 24-h flight test demonstrated that some individuals were capable of sustaining flight for over 7 h, suggesting a potential capacity for long-distance migration. These findings contribute to the development of a migration flight model and enhance our understanding of the flight behavior associated with long-distance migration in B. dorsalis.