Bionomics of Drosophilidae (Diptera) in Hokkaido : XI. Five Species of the Drosophila robusta Species Group

Drosophila sordidula, D. pseudosordidula, D. lacertosa, D. okadai, and D. neokadai, which belong to the Drosophila robusta species group, are multivoltine in Sapporo, northern Japan ; passing through mainly two, partially three, generations per year, and enter hibernal reproductive diapause from late August. Of these species, forest dwellers, D. sordidula and D. pseudosordidula, breed on sap fluxes, but waterside dwellers, D. okadai and D. neokadai, breed on rotting barks, though a waterside dweller, D. lacertosa, utilizes sap fluxes and rotting barks. There is inter-specific variation in the timing of the start of reproduction among waterside dwellers. This variation may facilitate to some extent the sharing of their breeding resources.