Methods for making siRNA comprise recombinantly coexpressing a Dicer protein with an R2D2 protein to form a complex comprising the R2D2 protein and the Dicer protein, and contacting the complex with a double-stranded (ds) RNA under conditions wherein the complex cleaves the dsRNA into siRNA. The R2D2 protein may be a Drosophila R2D2 protein and the Dicer protein may be a Drosophila Dicer-2 protein. The Dicer protein and the R2D2 protein may be coexpressed in insect cells, such as S2, Sf9 or Hi5 cells, using a baculovirus expression system.