Liquid fermentation of Beauveria bassiana and its survival and pathogenicity on greenhouse whitefly

In order to use entomopathogenic fungi as a commercial biological agent, their mass production is required. In the present study, the fermentation of one isolate of Beauveria bassiana was investigated using liquid culture media including TKI Broth culture medium with 5% of sugar beet molasses (TKI), liquid medium containing sugar beet molasses, yeast extract and multivitamin (MYM) and potato extract (P), potato extract plus 8% whey (PCh) and potato extract plus 5% molasses (PM). Moreover, the viability of the spores produced at two temperatures (room and refrigerator) was evaluated for nine months. Finally, the pathogenicity of spores obtained from different media was investigated on greenhouse whitefly nymphs under the laboratory and greenhouse conditions. In TKI Medium, the submerged conidia were produced showing the highest amount of conidia production (3.87×108 conidia/ml). The highest amount of blastospores was obtained in PCh medium with 2.37×108 blastospores/ml. In laboratory bioassay, blastospores of PCh medium showed the highest mortality rate (86.40%) on greenhouse whitefly nymphs and the lowest mortality rate were observed in submerged conidia from TKI medium with 74.03% mortality. In greenhouse bioassay, the mortality rate was between 43% and 50%. After nine months of storage at refrigerator, submerged conidia from TKI Broth and blastospores from P medium caused 25–30% mortality in whitefly nymphs in laboratory condition. No mortality was observed in greenhouse condition. According to the results, blastospores obtained from potato extract are introduced as a suitable liquid medium for mass production of this fungal isolate.