The synergy between climate change and transportation activities drives the propagation of an invasive fruit fly

Agricultural ecosystems are being increasingly exposed to the interactive effects of biological invasions, climate fluctuation, and human actions, with increasing temperatures and intense transportations expected to lead to the aggravation of alien species invasions. We thus assessed this expectation for a global invasive pest, the oriental fruit fly (Bactrocera dorsalis), by determining whether climate variation and transportation activities affect invasion dynamics of this epidemic in California. We found that both temperature fluctuation (growing degree days) and transportation activities (passenger volume) have significant effects on interannual fluctuations of the oriental fruit fly detection events and infested areas. In addition, both detection events and infested areas of the oriental fruit fly were significantly higher in warmer years, while annual precipitation had no significant effects on invasion dynamics of the oriental fruit fly. The growing degree days contributed much more to the invasion dynamics than passenger volume, while passenger volume facilitated an increase in infested area more than growing degree days. Then, we introduced a conceptual framework of synergy model of climate change and transportation activities to illustrate invasion dynamics of the oriental fruit fly, revealing both the invasion dynamics in a fixed cell according to growing degree days and the spatial transmission of invasive alien species by passenger volume. Our findings shed light on the spatial invasion dynamics of alien species, with potential implications for understanding the trajectories of biological invasions under changing future climates and transportation activities.