Isolation, characterization, culturing, and formulation of a new Beauveria bassiana fungus against Diaphorina citri

•An isolated Beauveria bassiana strain is highly virulent to citrus psyllids.•The fungal biphasic culture growth and conidial formulation were optimized.•Formulation enhanced conidial shelf life, stress resistance, and virulence. The Asian citrus psyllid, Diaphorina citri, is a worldwide destructive citrus pest. It aids in the transmission of a group of phloem-limited bacteria (Candidatus Liberibacter spp.) that leads to Huanglongbing (HLB) disease. In this study, a new Chinese native fungal strain (F-HY006) was isolated from the cadavers of D. citri collected from Ganzhou, Jiangxi in China (114°94′ E, 25°87′ N). The isolate was virulent towards adult female D. citri with corrected mortality of 76% and LT50 of 4.09 d after application of a suspension containing 107 conidia/ml (400 µl/citrus seedling). Morphologic and phylogenetic analyses identified this isolate as Beauveria bassiana. Based on its virulence against D. citri and growth characteristics (2.89 ± 0.28 × 105 conidia/cm2) on the PDA plate, biphasic (liquid–solid) cultivation for conidia production of B. bassiana F-HY006 was optimized using several nutritional and environmental factors. Soybean meal + cottonseed powder (1:1) and continuous fluorescent light resulted in the highest conidial production (5.7 × 109/g dry substrate). Moreover, the oil-based conidial formulation was optimized using sesame oil as an effective carrier, which resulted in a significant enhancement of the conidial shelf life, tolerance to thermal stress, and virulence against D. citri compared to unformulated conidia. Therefore, we have prepared a potential mycopesticide for the biological control of D. citri based on the optimized biphasic culture growth and formulation of an isolated virulent fungus, B. bassiana F-HY006.