Escola de Veterinária e Zootecnia, Universidade Federal de Goiás, Goiânia, Goiás, Brazil.
Departamento de Medicina Veterinária Preventiva, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
Vet Parasitol. 2024 Oct;331:110278. doi: 10.1016/j.vetpar.2024.110278. Epub 2024 Jul 31.
This study aimed to verify the number of R. microplus annual generations in irrigated and non-irrigated pastures compared to the constant ideal environment. It also sought to evaluate the biology of the non-parasitic phase of this tick for each generation in these different areas of pasture; assess the larvae population dynamics in the pasture of each tick generation, and evaluate the R. microplus population dynamics parasitizing cattle in non-irrigated pasture. In the field experiment, two sub-areas were subjected to artificial irrigation (IRRI-A and IRRI-B) with artesian water, while the other two remained non-irrigated (NIRRI-A and NIRRIG-B). When more than 75 % of the total surviving engorged females from all 90 repetitions of each area (irrigated or non-irrigated) produced mature larvae within one tick generation, two cattle were infested with approximately 10,000 R. microplus larvae from the tick colony used in this study. On the 22nd day post-infestation, a new tick generation was started by releasing these females in different areas (IRRI-B and NIRRIG-B). This procedure was repeated successively, and each year was analyzed independently. In both the non-irrigated and irrigated areas, there were five generations of R. microplus per year. It can be observed that there the number of annual generations of ticks in this region has increased when compared to 30 years ago. Under the constant ideal temperature and humidity conditions (B.O.D. chamber), R. microplus completed an average of 6.59 generations. In the environment, the longest generation was the first (July to October), while the 2nd, 3rd and 4th (December to March) were the most similar to B.O.D. conditions. Although the number of generations was the same in the different areas, the population density of R. microplus larvae was higher in the irrigated area, probably because the irrigation provided milder temperatures, higher relative humidity and lower saturation deficit values during about eight hours per day. Between the 3rd and 5th generation of ticks, there was an overlap of larvae in the pastures, belonging to different generations, and at each peak of infestation observed in cattle between these generations, there were up to 30 % of larvae from the previous generation, and consequently up to 70 % of larvae from the new generation.
本研究旨在验证在灌溉和非灌溉牧场与理想恒定环境相比，璃眼蜱（Rhipicephalus microplus）的年世代数量。它还试图评估在这些不同牧场区域中每一世代的这种蜱的非寄生阶段的生物学特性；评估每个蜱世代的牧场幼虫种群动态，并评估在非灌溉牧场寄生牛的璃眼蜱种群动态。在田间试验中，两个亚区（IRRI-A 和 IRRI-B）接受了自流井水的人工灌溉，而另外两个亚区（NIRRI-A 和 NIRRIG-B）则保持非灌溉状态。当每个区域（灌溉或非灌溉）的所有 90 次重复中，超过 75%的总存活饱血雌性产生成熟幼虫的时间在一个蜱世代内时，从本研究中使用的蜱群中大约 10000 只璃眼蜱幼虫感染了两头牛。在感染后第 22 天，通过在不同区域（IRRI-B 和 NIRRIG-B）释放这些雌性来开始新的蜱世代。这个过程连续重复，每年都单独进行分析。在非灌溉和灌溉区，每年都有五代璃眼蜱。可以观察到，与 30 年前相比，该地区蜱的年世代数量有所增加。在恒定的理想温度和湿度条件（B.O.D. 室）下，璃眼蜱平均完成 6.59 代。在环境中，最长的世代是第一代（7 月至 10 月），而第 2、3 和 4 代（12 月至 3 月）与 B.O.D.条件最为相似。尽管不同区域的世代数量相同，但灌溉区璃眼蜱幼虫的种群密度更高，这可能是因为灌溉提供了每天约 8 小时的更温和的温度、更高的相对湿度和更低的饱和度不足值。在蜱的第 3 到第 5 代之间，牧场中的幼虫有重叠，属于不同的世代，在这些世代之间观察到的每一次牛的感染高峰时，都有高达 30%的前一代幼虫，因此，新世代幼虫的比例高达 70%。
