Comparison of Acaricidal, Insecticidal, and Nerve Activities of Halfenprox (MTI-732) and Related Compounds

Abstract

The 2-(4-perhalomethoxyphenyl)-2-methylpropyl 3-phenoxybenzyl ethers related to etofenprox were prepared. Their insecticidal potencies against common cutworms and American cockroaches were close to the respective potency of etofenprox. The acaricidal potency of the CF₂BrO derivative (halfenprox) against two-spotted spider mites was about 200 times higher than etofenprox (C₂H₅O derivative). Halfenprox and related compounds induced repetitive discharges with a single electrical stimulus in the excised central nerve cord of the American cockroach as a class of conventional pyrethroids. These compounds also induced the slow-lasting sodium tail-current upon step repolarization of the crayfish axonal membrane. These nerve effects may be the major mode of action for the in vivo activities of this class of compounds. Hydrophobicity is likely to play some role in the variations of acaricidal potency.