Department of Medicine, Federal University of Lavras, Lavras, Minas Gerais, 37203-202, Brazil.
Department of Chemistry, Federal University of Lavras, Lavras, Minas Gerais, 37203-202, Brazil.
Exp Appl Acarol. 2023 Jun;90(1-2):99-117. doi: 10.1007/s10493-023-00809-z. Epub 2023 Jun 20.
Rhipicephalus microplus is the main ectoparasite of cattle and its parasitism can reduce weight gain of hosts, in addition to causing anemia, increasing the risk of myiasis, and resulting in the transmission of Babesia bovis and Anaplasma marginale, among other pathogens. The use of synthetic chemicals plays an important role in controlling these ticks. However, its frequent and indiscriminate use has contributed to the selection of resistant strains, resulting in greater interest in the search for natural-origin products. The shrub Callistemon viminalis (Myrtaceae), also known as weeping bottlebrush, is known for its antibacterial, acaricidal, repellent, and antifungal activities, but there are no reports in the literature about its effects on the internal morphology of ticks. This study aimed to extract and characterize the essential oil obtained from the leaves of C. viminalis. Additionally, its effects on the ovary morphology of engorged R. microplus were assessed through histological, histochemical, and morphometric techniques. Exposure to C. viminalis caused dose-dependent morphological changes, such as cellular alterations in the epithelial layer lining the ovary lumen and the pedicel, irregularity of the chorion and oocyte shape, changes in protein and carbohydrate content, decrease in oocyte size, reduction in the size of the nucleus as well as cytoplasmic and nucleolar vacuolation. Thus, C. viminalis essential oil exhibited a toxic effect on the reproductive system of R. microplus, which may result in the reproductive impairment of this tick species.
微小牛蜱是牛的主要外寄生虫，其寄生会降低宿主的体重增加，除了引起贫血，增加蝇蛆病的风险，并导致巴贝斯虫和边缘无浆体等病原体的传播。合成化学品的使用在控制这些蜱虫方面发挥了重要作用。然而，其频繁和无差别地使用导致了抗性菌株的选择，从而促使人们更加关注寻找天然来源的产品。灌木Callistemon viminalis（桃金娘科），也被称为垂枝瓶刷，以其抗菌、杀螨、驱虫和抗真菌活性而闻名，但文献中没有关于其对蜱虫内部形态影响的报道。本研究旨在从 C. viminalis 的叶子中提取和表征其获得的精油。此外，通过组织学、组织化学和形态计量学技术评估其对饱血微小牛蜱卵巢形态的影响。暴露于 C. viminalis 导致形态依赖性的变化，如卵巢腔和花梗上皮层的细胞改变，卵壳和卵母细胞形状不规则，蛋白质和碳水化合物含量变化，卵母细胞大小减小，核大小减小以及细胞质和核仁空泡化。因此，C. viminalis 精油对微小牛蜱的生殖系统表现出毒性作用，这可能导致该蜱种的生殖受损。
