Federal University of Mato Grosso do Sul, Campo Grande, Mato Grosso do Sul, Brazil.
Federal University of Acre, Rio Branco, Acre, Brazil.
Parasit Vectors. 2024 Mar 6;17(1):110. doi: 10.1186/s13071-024-06199-4.
The occurrence of higher winter temperatures in Brazilian areas with tropical and highland climates may result in a fifth peak of tick populations during winter in addition to the four generations previously described. Therefore, a strategic control protocol was developed with treatments in two seasons with the objective of controlling the generations of ticks that occur in spring/summer and those that occur in autumn/winter.
The study was conducted in Mato Grosso do Sul, Brazil, from the beginning of the rainy season, November 2020, to October 2021. In a randomized block design, 36 calves were distributed into three groups: (i) negative control; (ii) traditional strategic control in one season (SC1S), at the beginning of the rainy season; and (iii) strategic control in two seasons (SC2S), at the beginning and end of the rainy season. The SC1S strategic control group was treated on day 0, November 2020, and twice more with intervals of 42 days. The SC2S group received three more treatments beginning on day 182, May 2021, with intervals of 42 days. All treatments consisted of 5% fluralaner (Exzolt 5%) delivered via a pour-on dose of 1 mL/20 kg body weight. Counts of semi-engorged female ticks were performed on day 3 and every 14 days thereafter, and the animals were weighed at the same time.
Fluralaner showed a mean efficacy of more than 95% up to day 294. The two treated groups showed a decrease (P < 0.05) in the average number of ticks on day 3. In the SC2S group, the means were close or equal to zero throughout the study, while in the SC1S group, the means did not differ (P > 0.05) from those of the control group from day 231 onward. The final mean weight gain of each group was 76.40 kg, 98.63 kg, and 115.38 kg for the control, SC1S, and SC2S groups, respectively, differing (P < 0.05) from each other.
Therefore, three applications of fluralaner, with one application every 42 days from the beginning of the rainy season in the middle spring, resulted in effective tick control for 224 days. When three additional treatments were given in autumn/winter with intervals of 42 days between applications, tick counts were reduced throughout the year. This strategic control approach may be indicated in years with climatic conditions that allow that population peaks are expected to occur in the autumn/winter period.
巴西热带和高原气候地区冬季气温升高，可能导致除了之前描述的四个世代之外， ticks 种群在冬季出现第五个高峰。因此，制定了一项战略控制方案，在两个季节进行处理，目的是控制春季/夏季和秋季/冬季发生的 ticks 世代。
本研究于 2020 年 11 月雨季开始至 2021 年 10 月在巴西南马托格罗索州进行。采用随机区组设计，将 36 头小牛分为三组：（i）阴性对照；（ii）在雨季开始时进行一个季节的传统战略控制（SC1S）；和（iii）在雨季开始和结束时进行两个季节的战略控制（SC2S）。SC1S 战略控制组于 2020 年 11 月 20 日第 0 天进行处理，此后每隔 42 天再进行两次处理。SC2S 组于 2021 年 5 月 182 日开始接受另外三次处理，间隔 42 天。所有处理均使用 5%氟虫腈（Exzolt 5%）通过 1 毫升/20 公斤体重的浇铸剂量给药。在第 3 天和此后每隔 14 天进行半饱雌性 tick 计数，并同时称重动物。
氟虫腈的平均疗效在第 294 天之前超过 95%。两个处理组在第 3 天 tick 数量均减少（P<0.05）。在 SC2S 组中，整个研究期间平均值接近或等于零，而在 SC1S 组中，从第 231 天开始，平均值与对照组无差异（P>0.05）。每组的最终平均体重增加分别为 76.40 公斤、98.63 公斤和 115.38 公斤，各组之间存在差异（P<0.05）。
因此，从春季中期雨季开始，每隔 42 天应用一次氟虫腈，共应用三次，可有效控制 tick 224 天。当在秋季/冬季每 42 天间隔应用三次额外的处理时，全年 tick 计数减少。这种战略控制方法可能适用于气候条件允许预期在秋季/冬季出现种群高峰的年份。
