The Synergistic Ratio of Carbaryl with Piperonyl Butoxide as an Indicator of the Distribution of Multifunction Oxidases in the Insecta12

Abstract

The synergistic ratio of carbaryl with piperonyl butoxide has been evaluated from LD₅₀values with 54 species of insects from 8 orders and 37 families. The topical LD₅₀ for carbaryl in µg per g ranged from 0.3 for the red milkweed beetle, Tetraopes tetrophthalmus (Forster), to 4000 for Sarcophaga bullata Parker and the synergistic ratio from 1.5 for the convergent lady beetle, Hippodamia convergens Guerin Meneville, to 400 for S. bullata. The wide ranges of susceptibility to carbaryl and of synergistic ratio are interpreted as response to differences in the activities of multifunction oxidase detoxication which is inhibited by piperonyl butoxide. It is evident that these factors are highly variable in the Insecta.