An analysis of management strategies for cattle tick (Boophilus microplus) control in Australia.
Abstract
The performance of three control methods for Boophilus microplus (Can.) in Australia, acaricides, pasture spelling and tick resistant cattle, was assessed separately and in combination, using a population model and data obtained in the south-eastern Queensland region. In each case, the optimal strategy was first determined by computer search and was then assessed on the basis of its performance against low and high tick populations, its robustness, its long-term effects, its impact on the development of acaricide resistance and its additional costs of fencing, feeding and handling. For European breeds, which are susceptible to B. microplus, the analysis showed that acaricide dipping is best performed at regular 3-week intervals, beginning either in spring or summer. In the short-term, a sequence of 5 or 6 dippings was found to be the most profitable, although a reduction in dipping may be desirable when the development of acaricide resistance is considered. Two types of pasture spelling strategy were investigated: a single spelling period each year, and a rotational grazing system, involving frequent movement of cattle between two paddocks. Although the latter gives results comparable to dipping and is unaffected by the problem of acaricide resistance, the investment and maintenance costs involved in fencing are likely to be a deterrent. Single spelling appears more promising, especially if the cattle are dipped at each transfer, although pasture damage and/or feeding costs may prove prohibitive. Finally, the analysis suggested that, wherever feasible, the best strategy in the long run involves the adoption of resistant cattle combined with a single spelling period or limited dipping.