What is the nt identity when the species is drosophilia melanogaster?
CREATE TABLE "orthologs" (
  "species" text,
  "common_name" text,
  "protein_name" text,
  "accession_number" text,
  "nt_length" text,
  "nt_identity" text,
  "aa_length" text,
  "aa_identity" text,
  "e_value" text
);
SELECT "nt_identity" FROM "orthologs" WHERE "species"='Drosophilia melanogaster';