Fernández-Salas Agustín, Alonso-Díaz Miguel Ángel, Morales Rogelio Alejandro Alonso, Lezama-Gutiérrez Roberto, Cervantes-Chávez José Antonio
1 Facultad de Ingeniería Agronómica y Zootecnia, Complejo Regional Centro, Benemérita Universidad Autónoma de Puebla, Carretera Cañada-Morelos Km. 7.5, El Salado, C.P. 75460, Tecamachalco, Puebla, Mexico.
2 Centro de Enseñanza, Investigación y Extensión en Ganadería Tropical, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Martínez de la Torre, 93600, Veracruz, Mexico.
J Parasitol. 2018 Jun;104(3):275-282. doi: 10.1645/17-162. Epub 2018 Mar 16.
The objectives of the present study were to isolate Beauveria bassiana strains from cattle farm soils, analyze the phylogenetic relationships among the fungal strains isolated from these soils, and determine the acaricidal effect of B. bassiana isolates on engorged Rhipicephalus microplus tick strains resistant or susceptible to chemical acaricides. Six strains of B. bassiana were obtained and isolated from cattle farm soils in the Mexican tropics using the Galleria bait method, and their acaricidal effect was assessed against 2 populations of R. microplus ("Media Joya" chemical acaricide-resistant strain or "CLAR" chemical acaricide-susceptible strain) using the adult immersion test. The BbV03 strain produced 86.7% and 60% mortality in resistant and susceptible ticks on day 20, respectively, whereas the BbV04 strain produced 66.7% and 53.5% mortality in resistant and susceptible ticks on day 20, respectively. The BbV03 and BbV04 strains reduced egg laying on both R. microplus populations. There was no statistical difference in the acaricidal effect of B. bassiana strains among chemical acaricide-susceptible or -resistant R. microplus populations ( P > 0.05). The BbV03 strain was the most virulent against R. microplus with an LC of 2 × 10 and LC of 7 × 10 conidia/ml. We found that the 6 B. bassiana isolated clustered in the same clade with other previously reported B. bassiana strains (from GenBank) but were separated into 3 different sub-clades. This study shows that some B. bassiana strains are a promising coadjuvant alternative for biological tick control, including tick populations that are resistant to chemical acaricides. Beauveria bassiana is present in the pastures of tropic cattle farms, and there are genetic variations between B. bassiana strains living in this ecosystem that might play an important role in the natural control of R. microplus in cattle farm paddocks.
本研究的目的是从养牛场土壤中分离球孢白僵菌菌株，分析从这些土壤中分离出的真菌菌株之间的系统发育关系，并确定球孢白僵菌分离株对饱血的微小牛蜱菌株（对化学杀螨剂具有抗性或敏感性）的杀螨效果。使用大蜡螟诱饵法从墨西哥热带地区的养牛场土壤中获得并分离出6株球孢白僵菌，采用成虫浸泡试验评估它们对2个微小牛蜱种群（“Media Joya”化学杀螨剂抗性菌株或“CLAR”化学杀螨剂敏感菌株）的杀螨效果。BbV03菌株在第20天时，使抗性和敏感蜱的死亡率分别达到86.7%和60%，而BbV04菌株在第20天时，使抗性和敏感蜱的死亡率分别达到66.7%和53.5%。BbV03和BbV04菌株均减少了两个微小牛蜱种群的产卵量。在化学杀螨剂敏感或抗性的微小牛蜱种群中，球孢白僵菌菌株的杀螨效果没有统计学差异（P>0.05）。BbV03菌株对微小牛蜱的毒性最强，其LC50为2×10⁵和LC90为7×10⁶分生孢子/毫升。我们发现，分离出的6株球孢白僵菌与其他先前报道的（来自GenBank的）球孢白僵菌菌株聚集在同一进化枝中，但被分为3个不同的亚进化枝。本研究表明，一些球孢白僵菌菌株是生物蜱控制的有前景的辅助替代方法，包括对化学杀螨剂有抗性的蜱种群。球孢白僵菌存在于热带养牛场的牧场中，生活在该生态系统中的球孢白僵菌菌株之间存在遗传变异，这可能在养牛场围场中微小牛蜱的自然控制中发挥重要作用。
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