Earlier than expected introductions of the B mitotype in Brazil reveal an unprecedented, rapid invasion history.

During 1991, in Brazil, the presence of the exotic B mitotype was reported in São Paulo state. However, the duration from the time of initial introduction to population upsurges is not known. To investigate whether the 1991 B mitotype outbreaks in Brazil originated in São Paulo or from migrating populations from neighboring introduction sites, country-wide field samples of .