Toxicity to Boophilus microplus of Formamidine Acaricides and Related Compounds, and Modification of Toxicity by Certain Insecticide Synergists12

Abstract

Twenty-nine formamidines and related compounds displayed activity toward engorged female southern cattle ticks, as judged by reduction in oviposition and egg viability, but only the most toxic adulticides showed activity against larvae. Certain methylenedioxyphenyl compounds markedly antagonized the toxicity of the aryl N, N-dimethylformamidines to larvae, but in most cases they synergized the toxicity of the aryl N-methylformamidines. This fact suggested that the aryl N, N-dimethylformamidines possessed little if any innate toxicity to cattle tick larvae. The high toxicity of 2 diaryl methyl triazapentadiene compounds to engorged females and larvae was attributed in part to their ability to hydrolyze to their respective aryl N-methylformamidine derivatives.