Green Turbo: an innovative plant and algal extract–oil formulation for protecting fungal conidia from heat and UV radiation

Abiotic environmental stress remains a major limitation of microbial pesticides. To mitigate this stress, we evaluated the efficacy of a novel adjuvant formulation, composed of plant and algal extracts and oil (Green Turbo), to protect conidia of four entomopathogenic fungal isolates (Beauveria bassiana IBCB 66, Metarhizium robertsii ARSEF 2560, M. acridum ARSEF 324, and Cordyceps fumosorosea ARSEF 3889) and the mycoparasitic fungus Trichoderma lignorum (ARSEF 5176) against UV-B radiation, heat, osmotic stress (potassium chloride), and oxidative stress (menadione). Conidia of all isolates suspended in 1 mL of Green Turbo in 350 mL sterile distilled water, exposed for 1–12 h depending on the species, and assessed after 48 h were significantly more tolerant to both UV-B and heat than conidia suspended in 0.01% (v/v) Tween 80 solution. For instance, germination of unformulated B. bassiana and M. robertsii exposed to 45°C for 4 h was 4% and 33%, respectively, compared to 76% and 71% in formulated conidia. When exposed to UV-B radiation (847.9 mW m−2), germination in Green Turbo-formulated B. bassiana and T. lignorum remained over 90% after 4 h. Conidia formulated with Green Turbo were also slightly protected against osmotic stress, but not to oxidative stress. The present study demonstrated the efficacy of Green Turbo in protecting conidia of entomopathogenic fungi against the harmful effects of UV-B radiation and heat. Green Turbo is a promising formulation to increase the viability and efficacy of microbial biopesticides under adverse environmental conditions, offering a valuable tool for biological pest control.