Sands B, Ellse L, Wall R
Veterinary Parasitology and Ecology Group, University of Bristol, Bristol, U.K.
Med Vet Entomol. 2016 Mar;30(1):78-84. doi: 10.1111/mve.12148. Epub 2015 Nov 2.
Essential oils have shown good experimental potential as novel veterinary ectoparasiticides. However, if they are to be used as veterinary products, they must be available in formulations that are suitable for practical application against specific ectoparasites. Here, the efficacies of formulations containing 5% (v/v) lavender or tea tree oil, in combination with two emulsifiers [a surfactant, 5% (w/v) N-lauroylsarcosine sodium salt (SLS), and a soluble polymer, 5% (w/v) polyvinylpyrrolidone (PVP)], with or without 10% coconut oil, were tested in contact bioassays against the donkey chewing louse Bovicola ocellatus (Piaget) (Phthiraptera: Trichodectidae). Residual activity was quantified in open and closed containers; ovicidal efficacy was also examined. Exposure to either of 5% (v/v) lavender or tea tree oils with SLS or PVP resulted in louse mortality of 100%, but when coconut oil was included as an excipient, significantly lower efficacy was recorded. However, the formulations became significantly less effective after 2 h in open containers and 40 h in closed containers. The results confirm that the residual activity of essential oils is relatively transitory and the addition of 10% coconut oil does not prolong the period of insecticidal activity by slowing essential oil evaporation. Too short a period of residual activity is likely to be a significant impediment to the effective practical use of essential oils. However, unlike many synthetic pediculicides, the essential oils tested here were highly ovicidal, which suggests that prolonged residual activity may not be essential to kill newly hatched nymphs after treatment.
精油作为新型兽用体外寄生虫杀虫剂已显示出良好的实验潜力。然而，如果要将它们用作兽用产品，必须以适合实际应用于特定体外寄生虫的制剂形式提供。在此，测试了含有5%（v/v）薰衣草油或茶树油，并与两种乳化剂[一种表面活性剂，5%（w/v）N-月桂酰肌氨酸钠盐（SLS），和一种可溶性聚合物，5%（w/v）聚乙烯吡咯烷酮（PVP）]组合，有或没有10%椰子油的制剂对驴嚼虱Bovicola ocellatus（Piaget）（啮目：毛虱科）的接触生物测定效果。在开放和封闭容器中对残留活性进行了量化；还检查了杀卵效力。暴露于含有SLS或PVP的5%（v/v）薰衣草油或茶树油中的任何一种都会导致虱子死亡率达到100%，但当加入椰子油作为辅料时，记录到的效力显著降低。然而，在开放容器中2小时后以及在封闭容器中40小时后，制剂的效力显著降低。结果证实精油的残留活性相对短暂，添加10%椰子油并不能通过减缓精油蒸发来延长杀虫活性期。残留活性期过短可能是精油有效实际应用的一个重大障碍。然而，与许多合成杀虱剂不同，此处测试的精油具有高度杀卵性，这表明延长残留活性对于在处理后杀死新孵化的若虫可能并非必不可少。
