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.