Fig. 5

Mixing of brown planthopper (Nilaparvata lugens) populations in South Asia, South East Asia and East Asia. Brown planthoppers are resident breeders throughout tropical South and South East Asia. Each spring, brown planthoppers from the winter-breeding population in Indochina migrate north-eastwards to colonize East Asia (blue arrows), and it was generally considered that these made up a single South East / East Asian population which was distinct from the South Asian population, thus indicating a reasonably high level of migratory connectivity. However, a recent genetic analysis has indicated that a high degree of mixing occurs in northwest Indochina (overlapping blue and grey circles) due to regular exchange between here and South Asia (black and grey dashed arrows). Thus levels of migratory connectivity within the South Asian and South East / East Asian populations of brown planthoppers are lower than originally thought