PDF(Pubmed)
Abstract：
Following blood meals or questing bouts, hard ticks (Ixodidae) must locate moist off-host microhabitats as refuge. Soil-dwelling fungi, including entomopathogenic Beauveria bassiana (Bb), thrive in moist microhabitats. Working with six species of ixodid ticks in olfactometer bioassays, we tested the hypothesis that ticks avoid Bb. Contrary to our prediction, nearly all ticks sought, rather than avoided, Bb-inoculated substrates. In further bioassays with female black-legged ticks, Ixodes scapularis, ticks oriented towards both harmful Bb and harmless soil-dwelling fungi, implying that fungi-regardless of their pathogenicity-signal habitat suitability to ticks. Only accessible Bb-inoculated substrate appealed to ticks, indicating that they sense Bb or its metabolites by contact chemoreception. Bb-inoculated substrate required ≥24 h of incubation before it appealed to ticks, suggesting that they respond to Bb metabolites rather than to Bb itself. Similarly, ticks responded to Bb-inoculated and incubated cellulose but not to sterile cellulose, indicating that Bb detection by ticks hinges on the Bb metabolism of cellulose. 2-Methylisoborneol-a common fungal metabolite with elevated presence in disturbed soils-strongly deterred ticks. Off-host ticks that avoid disturbed soil may lower their risk of physical injury. Synthetic 2-methylisoborneol could become a commercial tick repellent, provided its repellency extends to ticks in diverse taxa.
摘要：
在血餐或询问后，硬蜱（Ixodidae）必须将潮湿的寄主微栖息地定位为避难所。土壤真菌，包括昆虫致病性球孢白僵菌（Bb），在潮湿的微生境中茁壮成长。在嗅觉计生物测定中与六种紫罗兰蜱一起工作，我们检验了蜱避开Bb的假设。与我们的预测相反,几乎所有的蜱虫都在寻找，而不是避免，Bb接种的底物。在对雌性黑腿蜱的进一步生物测定中，肩cap肌，针对有害的Bb和无害的土壤居住真菌的蜱，暗示真菌-无论其致病性如何-都预示着栖息地对蜱的适应性。只有可访问的接种Bb的底物吸引了蜱虫，表明他们通过接触化学感受感知Bb或其代谢物。接种Bb的底物在吸引蜱之前需要≥24小时的孵育，表明它们对Bb代谢物有反应，而不是对Bb本身有反应。同样，蜱对Bb接种和孵育的纤维素有反应，但对无菌纤维素没有反应，表明蜱对Bb的检测取决于纤维素的Bb代谢。2-甲基异冰片-一种常见的真菌代谢物，在受干扰的土壤中含量升高，强烈阻止了蜱虫。避免受干扰的土壤的非宿主蜱可能会降低其物理伤害的风险。合成的2-甲基异冰片可以成为商业驱虫剂，只要它的驱避性延伸到不同类群的蜱。
