Centro Nacional de Investigación Disciplinaria en Parasitología Veterinaria del Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias, Boulevard Cuauhnahuac No. 8534, Colonia Progreso Jiutepec, Morelos México C.P. 62550.
Parasitology. 2012 Feb;139(2):259-63. doi: 10.1017/S0031182011001843. Epub 2011 Oct 24.
The purpose of this study was to describe an unreported entomopathogenic fungus that naturally infects the cattle tick Rhipicephalus (Boophilus) microplus (Acari: Ixodidae). Engorged female ticks, showed symptoms of fungal infection after controlled tick infestation of cattle. Infected ticks developed a distinctive dark colour, a pale mould grew over the cuticle and the ticks eventually died covered with fungal conidiophores. The responsible fungus was isolated and cultured on mycological medium and submitted to microscopic morphology, biochemical phenotyping and 18S rRNA ribotyping analyses, which identified it as aflatoxin-producing Aspergillus flavus. Spores from the cultured fungus were experimentally sprayed over healthy engorged female ticks, obtaining an 80% prevalence of experimental infection of healthy ticks and their egg masses, the larval progeny after incubation under laboratory conditions was also infected. These results demonstrate that A. flavus is the causative agent of the natural fungal disease of the cattle tick R. microplus described here.
本研究的目的是描述一种新发现的能自然感染牛蜱（硬蜱属）的昆虫病原真菌。在对牛进行的人工蜱感染实验中，感染的牛蜱在吸食血液后会表现出真菌感染的症状。受感染的蜱虫会变成明显的深色，体表会出现白色霉菌，最终蜱虫会死于真菌的分生孢子梗。从受感染的蜱虫中分离出并在真菌培养基上培养的真菌，通过显微镜形态学、生化表型和 18S rRNA 核糖体分型分析，鉴定为产黄曲霉毒素的黄曲霉。从培养的真菌中提取的孢子被实验性地喷洒在健康的饱血雌性蜱虫上，获得了 80%的健康蜱虫及其卵群的实验感染率，在实验室条件下孵育的幼虫后代也被感染。这些结果表明，黄曲霉是这里所描述的牛蜱自然真菌感染的病原体。
