A comparison of cattle tick control by "conventional" acaricidal treatment, planned dipping, and pasture spelling

Abstract

Three comparable herds of cattle were grazed in a wet tropical area of north Queensland for the comparison of control measures against the cattle tick, Boophilus microplus. The cattle tick infestation of one herd was controlled by simulated "conventional" methods, the cattle receiving acaricidal treatment when the count of "standard" ticks (0.5 cm or more in length) on the right side averaged 20 or more per animal. The tick infestation of the second herd was controlled by dipping in acaricide at 21-day intervals, so that few of the tick larvae attaching to the cattle between dippings reached maturity. This was continued until the larval population in the pasture was greatly depleted. The procedure, for which the term planned dipping has been proposed, was repeated when the count of standard ticks on the right side averaged more than 20 per animal. The tick infestation of the third herd was controlled by grazing alternately in two adjacent paddocks, the interval between each transfer being sufficient to ensure that most of the ticks in the unstocked paddock had died. Acaricidal treatment was applied at times of paddock changes and also at other times if the tick count was more than 20 per animal. This procedure is known as pasture spelling. Over the 2 years of the experiment, planned dipping and pasture spelling resulted in increased efficiency in tick control. In comparison with the herd given conventional tick control, planned dipping resulted in no reduction in the number of acaricidal treatments, but the tick burden was reduced by 79%. Pasture spelling resulted in the number of acaricidal treatments being reduced by 60% and the tick burden by 64%.