Divergent migratory strategies along the East Asian insect flyway: A trade-off between flight power and atmospheric dependence.

Mass migration within the East Asian insect flyway is a globally significant ecological phenomenon, yet how insects with different flight capabilities utilize divergent strategies to exploit the same wind system remains a critical puzzle. We hypothesize that these strategies arise from a fundamental trade-off between active trajectory control and strategic atmospheric exploitation. To test this, we integrated long-term (11-year) field observations with atmospheric trajectory modeling to quantitatively assess the migratory performance of two species with disparate flight capacities: the oriental armyworm moth (Mythimna separata), a relatively powerful flier, and the brown planthopper (Nilaparvata lugens), a weak flier. Our simulations reveal that the strong-flying M. separata, which initiates its northward migration from mid-May, actively influences its trajectory, leveraging its self-powered flight to overcome slower, less directionally stable winds. In contrast, the weaker-flying N. lugens, which migrates about a month later, synchronizes its migration with a period of faster, more stable wind currents, allowing it to compensate for its limited flight power. These findings provide a mechanistic demonstration of how a trade-off between self-propelled power and atmospheric selectivity shapes migratory success. Ultimately, this study establishes that flight capacity is a key determinant of how migratory insects interact with their atmospheric environment, which in turn impacts their contrasting life histories within a shared flyway.