Arizona State University, School of Applied Sciences and Arts, Polytechnic Campus, 6073 S. Backus Mall, Wanner Hall 301B, Mesa, Arizona 85212, USA.
Northern Arizona University, Pathogen and Microbiome Institute, 1395 S Knoles Drive, Flagstaff, Arizona 86011, USA.
J Wildl Dis. 2024 Oct 1;60(4):806-817. doi: 10.7589/JWD-D-23-00172.
Soft ticks in the genus Ornithodoros occur throughout the Mojave Desert in southern Nevada, southeastern California, and parts of southwestern Utah and northwestern Arizona, USA, and are frequently observed parasitizing Mojave desert tortoises (Gopherus agassizii). However, limited research exists examining the relationship between ticks and desert tortoises. Mojave desert tortoises are listed as threatened by the US Fish and Wildlife Service, and as such, their populations are monitored and individual tortoise health is routinely assessed. These health assessments document the presence and abundance of ticks present on tortoises, but detailed examination of the relationship between ticks and tortoise health has been lacking. This study analyzed the relationship between tick presence and desert tortoise health assessments as a function of season, location, age (adult vs. juvenile), foraging behavior, evidence of clinical signs of disease, body condition score, and sex. Our results indicate that more ticks were found on tortoises in the summer than in any other season. Ticks were observed more frequently on captive tortoises versus wild tortoises, and more ticks were likely to be present on adult tortoises than on juveniles. Ticks were also more likely to be observed on tortoises that lacked evidence of foraging and on tortoises with observed clinical signs of disease. These findings provide valuable insights into the biology of ticks in relation to tortoises that may be useful for management of both captive and free-living threatened tortoise populations where ticks are detected. Our study also may improve understanding of potential tick-borne disease dynamics in the Mojave desert tortoise habitat, including Borrelia sp. carried by Ornithodoros ticks, which cause tick-borne relapsing fever in people.
软蜱属的软蜱分布于美国内华达州南部的莫哈韦沙漠、加利福尼亚州东南部和犹他州西南部以及亚利桑那州西北部，常寄生在莫哈韦沙漠龟（Gopherus agassizii）上。然而，目前关于蜱与沙漠龟关系的研究还很有限。莫哈韦沙漠龟被美国鱼类和野生动物管理局列为受威胁物种，因此对其种群进行监测，并定期评估个体龟的健康状况。这些健康评估记录了龟身上存在的蜱的数量和丰度，但缺乏对蜱与龟健康之间关系的详细研究。本研究分析了蜱的存在与沙漠龟健康评估之间的关系，考察了季节、地点、年龄（成年龟与幼年龟）、觅食行为、疾病临床症状的证据、身体状况评分和性别等因素的影响。研究结果表明，夏季龟身上的蜱比其他季节多。圈养龟身上的蜱比野生龟多，成年龟身上的蜱比幼年龟多。在缺乏觅食证据和观察到疾病临床症状的龟身上，也更容易发现蜱。这些发现为蜱与龟的生物学关系提供了有价值的见解，可能对管理圈养和自由生活的受威胁龟种群有用，因为在这些种群中检测到了蜱。本研究还可能有助于了解莫哈韦沙漠龟栖息地中潜在的蜱传疾病动态，包括由蜱携带的伯氏疏螺旋体，它会引起人类的蜱传回归热。
