Comparisons of fall armyworm haplotypes between the Galápagos Islands and mainland Ecuador indicate limited migration to and between islands
The migration of the fall armyworm (Spodoptera frugiperda) is of topical interest because of its recent
introduction and rapid dissemination throughout the Eastern Hemisphere. This study compares
fall armyworm from island and mainland locations in Ecuador to estimate migration behavior. The
Galápagos Islands is a province of Ecuador whose mainland coast lies approximately 1000 km to the
west and is the closest major land mass. Air transport modeling indicates that natural migration
from the mainland to the Galápagos is unlikely, suggesting that most, if not all, the introgressions
of mainland fall armyworm into the Galápagos are occurring through trade‑assisted transport
in contaminated cargo, which is ofoaded at the Galápagos port of entry in San Cristóbal island.
Haplotype studies are consistent with this limited migration and further show divergence in the fall
armyworm from San Cristóbal with those from the neighboring island of Santa Cruz despite their close
proximity (less than 100 km distance) and favorable winds for inter‑island fights. These observations
indicate that water poses a signifcant barrier for moth migration in this region, with human‑assisted
transport probably playing a more important role than natural migration.