Universidad Autónoma Metropolitana-Iztapalapa, Departamento de Biotecnología, San Rafael Atlixco 186, Col. Vicentina, C. P. 09340 CDMX, Mexico.
Universidad Autónoma Metropolitana-Lerma Departamento de Ciencias Ambientales, Av. de las Garzas 10, El panteón, C. P. 52005 Lerma de Villada, Mexico.
J Invertebr Pathol. 2023 Jun;198:107914. doi: 10.1016/j.jip.2023.107914. Epub 2023 Mar 21.
Tebuconazole (TEB) is a fungicide widely used in agriculture; however, its constant application has increased the emergence of resistant plant pathogenic fungal strains and reduced the effectiveness of fungi as biological control agents; for instance, the entomopathogenic and hyperparasitic fungus Akanthomyces lecanii, suitable for simultaneous biological control of insect pest and plant pathogenic fungi, is highly sensitive to fungicides. We carried out the induction of resistance to TEB in two wild type strains of A. lecanii by UV radiation and selective pressure in increasing fungicide gradients using a modified Microbial Evolution and Growth Arena (MEGA), to produce A. lecanii strains that can be used as biological control agent in the presence of tebuconazole. Nine UV-induced and three naturally adapted A. lecanii strains were resistant to TEB at the agriculturally recommended dose, and three irradiated strains were resistant to TEB concentration ten times higher; moreover, growth, sporulation rates, production of hydrolytic enzymes, and virulence against the hemipteran Coccus viridis, a major pest of coffee crops, were not affected in the TEB-resistant strains. These A. lecanii TEB-resistant strains would have a greater opportunity to develop and to establish themselves in fields where the fungicide is present and can be used in a combined biological-chemical strategy to improve insect and plant pathogenic fungal control in agriculture. Also, the selective pressure through modified MEGA plate methodology can be used for the adaptation of entomopathogenic filamentous fungi to withstand other chemical or abiotic stresses that limits its effectiveness for pest control.
戊唑醇（TEB）是一种广泛应用于农业的杀菌剂；然而，它的持续使用增加了抗药性植物病原真菌菌株的出现，并降低了真菌作为生物防治剂的有效性；例如，适合同时防治昆虫害虫和植物病原真菌的昆虫病原和超寄生真菌蜡蚧轮枝菌对杀菌剂高度敏感。我们通过紫外线辐射和在增加杀菌剂梯度的选择性压力对两种野生型蜡蚧轮枝菌进行了戊唑醇抗性诱导，使用改良的微生物进化和生长竞技场（MEGA），产生可以在存在戊唑醇的情况下用作生物防治剂的蜡蚧轮枝菌菌株。九株紫外线诱导和三株自然适应的蜡蚧轮枝菌菌株对农业推荐剂量的戊唑醇具有抗性，三株辐照菌株对戊唑醇浓度高出十倍具有抗性；此外，在戊唑醇抗性菌株中，生长、孢子形成率、水解酶的产生以及对咖啡作物主要害虫绿蝽的毒力没有受到影响。这些戊唑醇抗性蜡蚧轮枝菌菌株将有更大的机会在存在杀菌剂的田间发展和建立自己的地位，并可用于结合生物-化学策略，以改善农业中对昆虫和植物病原真菌的控制。此外，通过改良 MEGA 平板方法进行的选择性压力可用于使昆虫病原丝状真菌适应其他化学或非生物胁迫，从而限制其在害虫防治中的有效性。
