Easy raising of Drosophila melanogaster on a medium consisting of mashed potato flakes and a preservative solution.

Dueñas, I.E. ¹, M.E. Heres¹, P.L. Castañeda¹ , and U. Graf.^{2  1}UNAM-Iztacala, Av.  Los  Barrios s/n,  Los Reyes  Iztacala,  Tlalnepantla,  Edo. de México,  México.  ² Swiss Federal Institute of Toxicology (ETH), CH-8603 Schwerzenbach, Zürich, Switzerland.

Various types of culture media for raising Drosophila melanogaster have been developed from fermenting plant materials (corn meal, banana), to cooked preparations containing agar, and finally to formulations which need neither cooking nor sterilizing.  In the search for more economic, easy-to-prepare culture media, aquarists have proposed the use of mashed potato flakes as live food for fish.  In the case of Drosophila, this substrate initially posed some problems because of contamination with bacteria and molds when used with tap water alone or in combination with sugar or yeasts.

However, the use of mashed potato flakes in combination with a bactericidal and fungistatic solution commonly used in cooked media for Drosophila proved to be effective to keep this culture medium uncontaminated.  The solution is prepared with 1000 ml of tap water to which 5 ml of a 12% solution of Nipagin in alcohol, and 5 ml of a 10:1 solution of propionic acid:ortophosphoric acid are added.  To each 5 g of mashed potato flakes 20 ml of the preservative solution are added without subsequent stirring.  This medium provides consistency and nutritional requirements for raising healthy flies.  It doesn’t need cooking and sterilizing and is considerably less expensive than Drosophila instant media.  It is recommended that one always use the same brand of mashed potato flakes to minimize fluctuations in quality.  However, we recommend the use of this easy culture medium only for raising  the flies, but not for experimental purposes.

            References:  Guzmán Rincón, J., Javier Espinosa, and U. Graf  1998, Mut. Res. 412:  69-81.