IDICAL (INTA-CONICET), Instituto Nacional de Tecnología Agropecuaria (INTA) E.E.A. Rafaela, Ruta 34 Km 227, Rafaela, Santa Fe, Argentina.
Instituto Nacional de Tecnología Agropecuaria (INTA) E.E.A. El Colonia Benítez, Colonia Benítez, Chaco, Argentina.
Parasitol Res. 2024 Jun 7;123(6):232. doi: 10.1007/s00436-024-08256-4.
This work evaluated if strategic control based on no more than three or four annual treatments is useful to control Rhipicephalus microplus infestations on cattle when it is applied to intensive rotational grazing and silvopastoral systems with high stocking rates in subtropical areas. In the intensive rotational grazing system, three annual treatments with chemical acaricides were applied on cattle in two different schemes: between spring and early summer and from late winter and late spring. Strategic control based on three treatments with chemical acaricides from late winter to late spring plus an additional fourth treatment in summer was tested in the silvopastoral system. In the intensive rotational grazing systems, the control schemes allow to reach a significant reduction in the tick load on cattle considering a time interval from spring to autumn. However, the efficacy levels were not high enough in some specific moments, namely, the tick counts of summer and autumn (there were not significant differences between treated and control groups). The scheme evaluated in the silvopastoral grazing system yielded better results than those tested for the intensive rotational system, because significant differences in tick load between treated and control groups were observed in all post-treatment counts and when the analysis was performed for the whole study period. However, values of efficacy in the count-by-count comparison were disparate, ranging from 64.1 to 99.7. Although the efficacy values obtained in the silvopastoral system were better than those of the rotational grazing systems, the total tick load on treated cattle in autumn was not low enough (mean abundance values 25.14 and 38.14). Ticks were more evenly distributed among hosts in late summer and autumn than in spring or early summer, where few hosts carry most of the ticks. Some management strategies as intensive rotational systems or silvopastoral structures can lead to a more efficient forage use, but they imply greater tick challenge than in extensive grazing systems. In these situations, the schemes of strategic control bases on three or four annual treatments should be complemented with additional tactical treatments in late summer or autumn.
本研究旨在评估在亚热带地区高饲养密度的集约轮牧和农林复合系统中，每年进行不超过三到四次的策略性控制，是否有利于控制璃眼蜱对牛的感染。在集约轮牧系统中，在两个不同方案中对牛进行了三次年度化学杀蜱剂处理：春季至初夏和冬末至早春。在农林复合系统中，测试了从冬末至春末用化学杀蜱剂进行三次策略性控制，外加夏季进行第四次处理的方案。在集约轮牧系统中，控制方案允许在从春季到秋季的时间间隔内，显著降低牛身上的蜱虫数量。然而，在某些特定时刻，如夏季和秋季的蜱虫计数，效果水平并不高（处理组和对照组之间没有显著差异）。在农林复合放牧系统中评估的方案比集约轮牧系统中测试的方案效果更好，因为在所有治疗后计数以及整个研究期间的分析中，处理组和对照组之间的蜱虫数量均存在显著差异。然而，在逐次计数的比较中，疗效值存在差异，范围从 64.1%到 99.7%。尽管农林复合系统中获得的疗效值优于轮牧系统，但秋季处理牛的总蜱虫数量仍然不低（平均丰度值分别为 25.14 和 38.14）。与春季或初夏相比，夏季和秋季蜱虫在宿主间的分布更加均匀，此时很少有宿主携带大部分蜱虫。一些管理策略，如集约轮牧系统或农林复合结构，可以提高草料的利用效率，但与粗放放牧系统相比，它们会带来更大的蜱虫挑战。在这些情况下，每年进行三到四次的策略性控制方案应辅以夏季或秋季的额外战术性处理。
