U.S. Geological Survey, Fort Collins Science Center, Fort Collins, Colorado, United States of America.
Prairie Wildlife Research, Stevens Point, Wisconsin, United States of America.
PLoS One. 2022 Aug 8;17(8):e0272419. doi: 10.1371/journal.pone.0272419. eCollection 2022.
Plague, a widely distributed zoonotic disease of mammalian hosts and flea vectors, poses a significant risk to ecosystems throughout much of Earth. Conservation biologists use insecticides for flea control and plague mitigation. Here, we evaluate the use of an insecticide grain bait, laced with 0.005% fipronil (FIP) by weight, with black-tailed prairie dogs (BTPDs, Cynomys ludovicianus). We consider safety measures, flea control, BTPD body condition, BTPD survival, efficacy of plague mitigation, and the speed of FIP grain application vs. infusing BTPD burrows with insecticide dusts. We also explore conservation implications for endangered black-footed ferrets (Mustela nigripes), which are specialized predators of Cynomys.
During 5- and 10-day laboratory trials in Colorado, USA, 2016-2017, FIP grain had no detectable acute toxic effect on 20 BTPDs that readily consumed the grain. During field experiments in South Dakota, USA, 2016-2020, FIP grain suppressed fleas on BTPDs for at least 12 months and up to 24 months in many cases; short-term flea control on a few sites was poor for unknown reasons. In an area of South Dakota where plague circulation appeared low or absent, FIP grain had no detectable effect, positive or negative, on BTPD survival. Experimental results suggest FIP grain may have improved BTPD body condition (mass:foot) and reproduction (juveniles:adults). During a 2019 plague epizootic in Colorado, BTPDs on 238 ha habitat were protected by FIP grain, whereas BTPDs were nearly eliminated on non-treated habitat. Applications of FIP grain were 2-4 times faster than dusting BTPD burrows.
Deltamethrin dust is the most commonly used insecticide for plague mitigation on Cynomys colonies. Fleas on BTPD colonies exhibit the ability to evolve resistance to deltamethrin after repeated annual treatments. Thus, more tools are needed. Accumulating data show orally-delivered FIP is safe and usually effective for flea control with BTPDs, though potential acute toxic effects cannot be ruled out. With continued study and refinement, FIP might be used in rotation with, or even replace deltamethrin, and serve an important role in Cynomys and black-footed ferret conservation. More broadly, our stepwise approach to research on FIP may function as a template or guide for evaluations of insecticides in the context of wildlife conservation.
鼠疫是一种广泛分布于哺乳动物宿主和跳蚤媒介的人畜共患疾病，对地球大部分地区的生态系统构成重大威胁。保护生物学家使用杀虫剂来控制跳蚤和减轻鼠疫。在这里，我们评估了一种用 0.005%氟虫腈（FIP）调味的昆虫颗粒诱饵在黑尾草原犬鼠（BTPD，Cynomys ludovicianus）中的使用情况。我们考虑了安全性措施、跳蚤控制、BTPD 身体状况、BTPD 生存、减轻鼠疫的效果以及与用杀虫剂粉尘注入 BTPD 洞穴相比，FIP 颗粒的应用速度。我们还探讨了对濒临灭绝的黑脚雪貂（Mustela nigripes）的保护意义，黑脚雪貂是 Cynomys 的专门捕食者。
在 2016-2017 年美国科罗拉多州进行的为期 5-10 天的实验室试验中，20 只黑尾草原犬鼠很容易就吃掉了 FIP 颗粒，而 FIP 颗粒对它们没有明显的急性毒性作用。在 2016-2020 年在美国南达科他州进行的野外实验中，FIP 颗粒在至少 12 个月，在许多情况下长达 24 个月内抑制了 BTPD 上的跳蚤；由于未知原因，一些地点的短期跳蚤控制效果较差。在南达科他州一个鼠疫循环似乎较低或不存在的地区，FIP 颗粒对 BTPD 的生存没有可检测到的积极或消极影响。实验结果表明，FIP 颗粒可能改善了 BTPD 的身体状况（体重：脚）和繁殖（幼体：成体）。在 2019 年科罗拉多州的一次鼠疫流行中，238 公顷生境中的 BTPD 受到了 FIP 颗粒的保护，而在未处理的生境中，BTPD 几乎被消灭。FIP 颗粒的应用速度比粉尘处理 BTPD 洞穴快 2-4 倍。
在 Cynomys 群体中，溴氰菊酯粉尘是最常用的鼠疫缓解杀虫剂。黑尾草原犬鼠群体上的跳蚤表现出在每年重复处理后对溴氰菊酯产生抗药性的能力。因此，需要更多的工具。积累的数据表明，口服氟虫腈对 BTPD 控制跳蚤是安全且通常有效的，尽管不能排除潜在的急性毒性作用。随着进一步的研究和改进，FIP 可能会与溴氰菊酯一起使用，甚至取代溴氰菊酯，并在 Cynomys 和黑脚雪貂的保护中发挥重要作用。更广泛地说，我们对 FIP 的研究分步骤方法可以作为在野生动物保护背景下评估杀虫剂的模板或指南。
