Murigu Mercy M, Nana Paulin, Waruiru Robert M, Nga'nga' Chege J, Ekesi Sunday, Maniania Nguya K
International Centre of Insect Physiology and Ecology (ICIPE), P.O. Box 30772-00100, Nairobi, Kenya; University of Nairobi, Department of Veterinary Pathology, Microbiologyand Parasitology, P.O. Box 29053-00625, Kangemi-Nairobi, Kenya.
International Centre of Insect Physiology and Ecology (ICIPE), P.O. Box 30772-00100, Nairobi, Kenya; University of Dschang, Faculty of Agriculture and Agricultural Sciences, School of Wood, Water and Natural Resources, P.O. Box 786, Ebolowa, Cameroon.
Vet Parasitol. 2016 Jul 30;225:12-8. doi: 10.1016/j.vetpar.2016.05.026. Epub 2016 May 24.
Rhipicephalus decoloratus causes serious economic losses in cattle industry every year in East Africa. Biological control using entomopathogenic fungi is seen as a promising alternative to chemical acaricides being used for their control. The pathogenicity of Metarhizium anisopliae and of Beauveria bassiana isolates was tested in the laboratory against amitraz-resistant and amitraz-susceptible strains of R. decoloratus. Unfed larvae were sprayed with conidial suspensions of 1×10(9) conidia ml(-1). Fungal isolates were pathogenic to R. decoloratus larvae, causing mortality of between 10.0 and 100% and between 12.1 and 100% of amitraz-susceptible and amitraz-resistant strains, respectively. The LT50 values of selected fungal isolates varied between 2.6-4.2days in amitraz-susceptible strain and between 2.8-3.9days in amitraz-resistant strain. The LC50 values varied between 0.4±0.1 and 200.0±60×10(3) conidia ml(-1) and between 0.1±0.1 and 200.0±31.0×10(3) conidia ml(-1) in amitraz-susceptible and amitraz-resistant strains, respectively. Metarhizium anisopliae isolate ICIPE 7 outperformed the other isolates and was selected for compatibility study with amitraz and field trial. ICIPE 7 was compatible with amitraz. In the field, four treatments including control, ICIPE 7 alone, amitraz alone and ICIPE 7/amitraz were applied on cattle. All the treatments significantly reduced the number of ticks on all the sampling dates: day 7 (F3,8=3.917; P=0.0284), day 14 (F3,8=9.090; P=0.0275), day 21 (F3,8=37.971; P=0.0001) and day 28 (F3,8=8.170; P=0.0016) compared to the control. Results of the present study indicate that ICIPE 7 can be used for the management of amitraz-resistant strain of R. decoloratus.
在东非，彩饰璃眼蜱每年给养牛业造成严重的经济损失。利用昆虫病原真菌进行生物防治被视为一种有前景的替代方法，可替代目前用于防治该蜱的化学杀螨剂。在实验室中，对绿僵菌和白僵菌分离株针对抗双甲脒和敏感双甲脒的彩饰璃眼蜱菌株的致病性进行了测试。未进食的幼虫用浓度为1×10(9) 个孢子/毫升的分生孢子悬浮液进行喷雾处理。真菌分离株对彩饰璃眼蜱幼虫具有致病性，分别导致敏感双甲脒菌株和抗双甲脒菌株的死亡率在10.0%至100%以及12.1%至100%之间。所选真菌分离株在敏感双甲脒菌株中的半数致死时间（LT50）值在2.6至4.2天之间，在抗双甲脒菌株中为2.8至3.9天。在敏感双甲脒菌株和抗双甲脒菌株中，半数致死浓度（LC50）值分别在0.4±0.1至200.0±60×10(3) 个孢子/毫升以及0.1±0.1至200.0±31.0×10(3) 个孢子/毫升之间。绿僵菌分离株ICIPE 7的表现优于其他分离株，并被选用于与双甲脒的相容性研究和田间试验。ICIPE 7与双甲脒具有相容性。在田间，对牛应用了包括对照、单独使用ICIPE 7、单独使用双甲脒以及ICIPE 7/双甲脒在内的四种处理方法。与对照相比，在所有采样日期（第7天：F3,8 = 3.917；P = 0.0284；第14天：F3,8 = 9.090；P = 0.0275；第21天：F3,8 = 37.971；P = 0.0001；第28天：F3,8 = 8.170；P = 0.0016），所有处理均显著减少了蜱的数量。本研究结果表明，ICIPE 7可用于管理抗双甲脒的彩饰璃眼蜱菌株。
