This study compared four strategies for controlling Rhipicephalus microplus in steers under field conditions in the savannah Biome (Cerrado) of Brazil, including two control groups: traditional strategic control (T1), palliative control (T2), an alternative experimental strategic control (T3), and pasture spelling during the dry season (T4). Twenty-four Girolando steers were allocated into four groups (n = 6) and monitored for tick infestation over an 11-month period. Efficacy was assessed using cumulative and monthly tick counts on steers, tick-free periods, and indicators of pasture disinfestation. Mean cumulative counts of ticks per animal were 10.3 (T1), 33.5 (T2), 10.2 (T3), and 10.1 (T4), corresponding to reductions of 69.3 %, 69.6 %, and 69.9 % in T1, T3, and T4, respectively, relative to the palliative control. Aggregated tick counts were significantly higher only in T2, whereas all strategic approaches resulted in similarly lower overall infestation levels. Tick-free periods differed markedly among treatments: T1 achieved the longest cumulative tick-free period (169 days), followed by T3 (142 days, occurring in two discontinuous phases) and T4 (134 days), while no sustained tick-free period was observed in T2. Notably, pasture spelling produced the longest tick-free period independent of residual acaricide activity (64 days). The non-parasitic phase of tick populations was suppressed during the cold and dry season. From May to August, larval production and survival in the field were reduced by 89.3 % and 67 %, respectively. Pasture infestation declined during spelling, attaining absence of larval clusters after 99 days of cattle removal. Overall, pasture spelling provided tick control comparable to acaricide-based strategies while substantially reducing chemical use.
Rodrigues et al. (Sat,) studied this question.