Miller R J, George J E, Guerrero F, Carpenter L, Welch J B
USDA-ARS Knipling-Bushland US Livestock Insects Research Laboratory, Kerrville, TX 78028, USA.
J Med Entomol. 2001 Mar;38(2):298-302. doi: 10.1603/0022-2585-38.2.298.
Rhipicephalus sanguineus (Latreille) were collected from the Corozal Army Veterinary Quarantine Center in Panama and characterized for resistance to five classes of acaricides. These ticks were highly resistant to permethrin, DDT, and coumaphos; moderately resistant to amitraz; and not resistant to fipronil when compared with susceptible strains. Resistance to both permethrin and DDT may result from a mutation of the sodium channel. However, synergist studies indicate that enzyme activity is involved. The LC50 estimate for permethrin was lowered further in the Panamanian strain then in susceptible strains with the addition of triphenylphosphate (TPP), but not with the addition ofpiperonyl butoxide (PBO). This suggests that esterases and not oxidases are responsible for at least some pyrethroid resistance. Elevated esterase activity and its inhibition by TPP were confirmed by native gel electrophoresis. The LC50 estimate obtained for coumaphos in the Panamanian strain was not lowered further than what was observed for susceptible strains by the addition of TPP or PBO. This indicates that enzyme activity might not be involved in coumaphos resistance. Resistance to amitraz was measured through a modification of the Food and Agriculture Organization Larval Packet Test. All tick strains were found to be susceptible to fipronil.
血红扇头蜱（拉特雷尔）采自巴拿马科罗萨尔陆军兽医检疫中心，并对其对五类杀螨剂的抗性进行了鉴定。与敏感品系相比，这些蜱对氯菊酯、滴滴涕和蝇毒磷具有高度抗性；对双甲脒具有中度抗性；对氟虫腈不具有抗性。对氯菊酯和滴滴涕的抗性可能是由钠通道突变引起的。然而，增效剂研究表明酶活性也参与其中。在巴拿马品系中，添加磷酸三苯酯（TPP）后，氯菊酯的半数致死浓度（LC50）估计值比敏感品系进一步降低，但添加胡椒基丁醚（PBO）后则没有降低。这表明酯酶而非氧化酶至少对部分拟除虫菊酯抗性起作用。通过天然凝胶电泳证实了酯酶活性升高及其被TPP抑制。在巴拿马品系中，添加TPP或PBO后，蝇毒磷的LC50估计值并未比敏感品系观察到的进一步降低。这表明酶活性可能不参与对蝇毒磷的抗性。通过对粮农组织幼虫包囊试验进行改进来测定对双甲脒的抗性。发现所有蜱品系对氟虫腈均敏感。
