Field Tests in Mexico with New Insecticides and Arsenic for the Control of Boophilus Ticks on Cattle

Abstract

Mortality of adults, reproduction of surviving females, and prevention of nymphal molting of Boophilus annulatus (Say) and B. annulatus microplus (Canestrini) collected from cattle at 4 posttreatment intervals were the criteria used to evaluate the effectiveness of 11 insecticides as sprays and 4 as dips on 9 ranches in Mexico. Of the compounds tested as single sprays, 1% carbaryl, 0.25% General Chemical 4072 [2-chloro-1-(2,4-dichlorophenyl) vinyl diethyl phosphate], 0.5% toxaphene, and 1% trichlorfon were highly effective in controlling Boophilus ticks; 0.05% carbophenothion, 0.15% dioxathhion, 0.25% fenthion, and 0.1% General Chemical 3582 [1-(2,5-dichlorophenyl)-2,2-dichlorovinyl diethyl phosphate] were less effective; and least effective were 0.05% diazinon, 0.05% lindane, and 0.5% Ruelene® (4- tert- butyl-2-chlorophenyl methyl methylphosphoramidate). Of the four compounds tested as single dips, 0.12% and 0.25% coumaphos, and 0.15% and 0.2% dioxathion wee highly effective in controlling both varieties, and 0.06% coumaphos and 0.1% dioxathiion were somewhat less so. Ronnel at 0.5% was only partially effective, and 0.25% and 0.125% runnel were proportionately less effective. Under the conditions of these limited tests, arsenic at 0.2% As2O3 was inferior to coumaphos and dioxathion against B. annulatus. Arsenic at either 0.2% or 0.22% As2O3 was the least effective of the 4 insecticides against B. a. microplus , and no difference between the 2 concentrations could be detected.