Studies on commercial octamethylpyrophosphoramide (Schradan). V. —Insecticidal Comparisons of the Two Main Constituents

Solutions of pure octamethylpyrophosphoramide, (Me 2 N) 4 P 2 O 3 , and of a mixture of this insecticide with its higher homologue (Me 2 N) 5 P 3 O 5 , were sprayed on plants and the insecticidal effects were compared. Three species of aphids were used on chrysanthemum plants, and two species on Windsor bean seedlings. The different insect species showed not only different levels of susceptibility to the insecticides and different relationship between dosage and response, but also different relative effects between the two insecticide samples. In particular, the mixture containing (Me 2 N) 5 P 3 O 5 was found more toxic or less toxic than pure (Me 2 N) 4 P 2 O 3 , according to the insects used for testing. In all cases, the insecticidal activity of the mixture was greater than would be expected from its content of (Me 2 N) 4 P 2 O 3 , alone; it is concluded that the higher homologue is itself an insecticide of the same order of toxicity as (Me 2 N) 4 P 2 O 3 , but rather more or less toxic than this according to the insects used for testing.