Exposure of House Flies to Residues of Certain CheluicaIs Before Exposure to Residues of Pyrethrum

Abstract

House flies were exposed for 5 min. to a residue of 40 mg./sq. ft. of 51 chemicals selected as possible synergists and after intervening periods of 5 min., 4, 24, and 48 hrs. were then exposed to residue of 0.5 mg./sq. ft. of pyrethrum. Piperonyl butoxide, [image]-isobutylundecylenamide, sesamin concentrate, piperonyl cyclonene, the ethyl ester of piperonylic acid, and n-Propyl Isome, in the order given, were outstanding in increasing the effectiveness of pyrethrins. Both knock-down time and mortality were bettered over that obtained by exposure to pyrethrum only. No visual injury or toxic symptoms were apparent in synergist-treated flies, but apparently the synergists lowered the resistance of flies to pyrethrum poisoning. When flies were exposed to mixtures containing 0.5 mg. of pyrethrum and 0.5 mg. of adjuvants, piperonyl butoxide, [image]- isobutyl-undecylenamide and sesamin concentrate showed the greatest synergistic properties.