Rust M K, Denholm I, Dryden M W, Payne P, Blagburn B L, Jacobs D E, Mencke N, Schroeder I, Vaughn M, Mehlhorn H, Hinkle N C, Williamson M
Department of Entomology, University of California, Riverside, Riverside, CA 92521-0314, USA.
J Med Entomol. 2005 Jul;42(4):631-6. doi: 10.1093/jmedent/42.4.631.
The susceptibility of four laboratory strains of cat fleas, Ctenocephalides felis (Bouche), to imidacloprid was determined by three different laboratories, by using a standardized bioassay protocol. The probit lines generated by the different laboratories were very similar, with LC50 values ranging from 0.32 to 0.81 ppm. Based on these data, a diagnostic dose (DD) of 3 ppm imidacloprid in larval rearing media was provisionally identified for detecting shifts in tolerance, possibly as a consequence of incipient imidacloprid resistance. None of the larvae from the susceptible laboratory strains survived the DD. Eighteen field-collected isolates were evaluated for their susceptibility to imidacloprid and to validate a DD of 3 ppm. Probit lines from 18 field-collected isolates were very similar, with LC50 values ranging from 0.14 to 1.52 ppm. When exposed to the DD, between 3 and 10% of the exposed larvae emerged as adults from only three of the 18 isolates. All other field isolates gave 100% mortality at the DD. Under the criteria established (>5% survivorship at 3 ppm), two isolates would be established on mammalian hosts and more extensive tests conducted to exclude or confirm the presence of resistance. The DD of 3 ppm is robust enough to eliminate most of the susceptible isolates collected until today, yet low enough to identify possible isolates for further testing.
通过使用标准化生物测定方案，由三个不同实验室测定了四种实验室品系的猫栉首蚤（Ctenocephalides felis (Bouche)）对吡虫啉的敏感性。不同实验室生成的概率线非常相似，LC50值范围为0.32至0.81 ppm。基于这些数据，临时确定在幼虫饲养培养基中吡虫啉的诊断剂量（DD）为3 ppm，以检测耐受性的变化，这可能是由于初期吡虫啉抗性导致的。来自敏感实验室品系的幼虫在该诊断剂量下均未存活。对18个野外采集的分离株进行了吡虫啉敏感性评估，并验证3 ppm的诊断剂量。来自18个野外采集分离株的概率线非常相似，LC50值范围为0.14至1.52 ppm。当暴露于诊断剂量时，在18个分离株中只有3个分离株中有3%至10%的暴露幼虫羽化为成虫。所有其他野外分离株在诊断剂量下死亡率均为100%。根据既定标准（3 ppm时存活率>5%），将在哺乳动物宿主上建立两个分离株，并进行更广泛的测试以排除或确认抗性的存在。3 ppm的诊断剂量足以消除至今收集的大多数敏感分离株，但又足够低以识别可能需要进一步测试的分离株。
