[Action of dimilin on carotene formation by Blakeslea trispora]

Dimilin, an insecticide, was added together with a number of surfactants; it was found to penetrate into the cell of microscopic fungi where it slightly inhibited biomass production but had no effect on chitin biosynthesis. The insecticide was shown to be capable of inhibiting the secondary processes of biosynthesis, namely, carotene synthesis in the fungus. A possible mechanism of dimilin action in insects and fungi is discussed on the basis of the results.