Screening of Acaricides for Control of One-Host Ticks, 1983

Abstract

Abstract Larvae of the cattle tick, Boophilusannulatus (Say), and the southern cattle tick, B. microplus (Canestrini), in colony at the Cattle Fever Tick Research Laboratory, Falcon Heights and Mission, Tex., and the tropical horse tick, Anocentor nitens (Neumann), and the winter tick, Dermacentor albipictus (Packard), in colony at Kerrville, Tex., are placed onto cattle. Engorged females that detach naturally are tested. Usually candidate compounds (technical materials) are formulated as emulsifiable concentrates containing 25% active ingredient (AI), 65% zylene, and 10% Triton X-100. Compounds not soluble in xylene are usually formulated (14.3% AI) in a 1:1 mixture of N-methyl-2-pyrrolidinone and the xylene, Triton X-100 combination. Commercial wettable powders or emulsifiable concentrates may be used. All formulations are mixed with water immediately before treatment. Acaricides are routinely tested at 1, 0.1, and 0.01% AI; the lesser concentrations are obtained by serial dilution of the 1% concentration. Prior to treatment, ticks are washed, dried, sorted into groups of 10, and weighed. For treatment, groups of ticks are placed into 20 to 25 ml of acaricide, which is stirred vigorously for 30 sec and then poured through a screen that retains the ticks. Drained ticks are placed on paper toweling to dry and held in 8-dram shell vials at 27±l°C and >80% RH for oviposition. After 2 to 3 weeks, the female ticks are discarded and the eggs are weighed and held for another 4 to 5 weeks when percentage hatch is estimated visually. Other groups of 10 ticks, which are dipped in an emulsion of 2.6% xylene and 0.4% Triton X-100 or the mixture of xylene, Triton X-100, and pyrrolidinone (equivalent to the 1% concentration of AI) and handled as treated ticks, are used as treated controls.