Abstract Tuta absoluta is a major pest of tomato that first invaded Japan in 2021. However, the mechanism of its invasion remains unclear. We tested the hypothesis that this species migrates from overseas to Japan by analysing the strontium radiogenic isotope ratio 87 Sr/ 86 Sr of individuals trapped in Japan and tracing their backward migration trajectories. In southern and western Japan, individuals with higher 87 Sr/ 86 Sr ratios than those of host plants in the Japanese trapping areas were captured simultaneously at multiple sites during periods of strong westerly winds blowing from the East Asian continent, suggesting that they had arrived from outside the study area. The endpoints of the backward trajectories for these captures were distributed across the continental regions where T. absoluta likely occurred. The results suggest the possibility of overseas migration, thereby supporting our hypothesis. Although further studies, such as the investigation of potential source regions, are needed, this study provides an important ecological perspective for establishing effective pest management strategies for this species.
Komatsuzaki et al. (2026) studied this question.