بررسی روند زنده‌مانی کنیدی قارچ بیمارگر حشرات Beauveria bassiana در فرمولاسیون‌های مختلف روغنی

To utilize native insect-pathogenic fungi as biological control agents, it’s crucial to formulate and maintain their viability. In a recent study, researchers investigated the conidial survival of isolate A1-1 from the entomopathogenic fungus Beauveria bassiana in oil-based formulations. Notably, this isolate demonstrated superior performance against insect pests, including the greenhouse whitefly, larvae of the large wax moth, and cotton bollworm. Fungal conidia were propagated on the rice bran substrate and separated from the substrate with a hand sieve. The conidia were mixed in four oily formulations: (1) a concentrated suspension (30%) based on mineral oil (liquid paraffin) containing conidia, liquid paraffin, tween 80, carboxymethyl cellulose, and talc; (2) a mixture of sunflower oil and diesel in a 3:7 ratio; (3) pure liquid paraffin; and (4) sunflower oil. These mixtures were stored for six months at two different temperatures: room temperature (25 ± 5 °C) and in a refrigerator (4 °C). The viability (CFU) of conidia was evaluated at one hour after formulation and at 2, 4, and 6 months after storage. Remarkably, significant differences were observed in the survival of conidia across the studied treatments (P < 0.05). At room temperature, the log-transformed fungal colony-forming unit (Log CFU/ml) counts for the various formulations after six months of storage were as follows: concentrated suspension (7.28 to 5.53), mixture of sunflower oil and diesel (7.69 to zero), liquid paraffin (7.69 to zero), and sunflower oil (7.77 to zero). At refrigerator temperature, the log-transformed fungal colony-forming unit (Log CFU/ml) counts for various formulations after six months of storage were as follows: concentrated suspension (7.28 to 7.15), mixture of sunflower oil and diesel (7.69 to zero), liquid paraffin (8.19 to 6.39), and sunflower oil (7/77 to 6/55). Overall, it is evident that maintaining the fungal formulation at a lower temperature significantly enhances the survival of fungal conidia. Noticeably, the concentrated suspension formulation outperformed other formulations at both studied temperatures.