Evaluation of Beauveria bassiana isolates as potential agents for control of Hyphantria cunea (Lepidoptera: Arctiidae).
Aim: The fall webworm, Hyphantria cunea (Drury) (Lepidoptera: Arctiidae), a destructive invasive pest and native to North America, has spread from Dandong city, Liaoning province of northeastern China to Wuhu city, Anhui province of southeastern China. Effective control measures are urgently needed. In this study, Beauveria bassiana isolates from H. cunea were examined for biological characteristics and virulence, to assess their potential as a bio-control agent for H. cunea. Methods: The biological characteristics of seven isolates (Bb01-1, Bb08-5, Bb08-6, Bb08-11, Bb22-2, Bb22-3 and Bb22-5), including colony morphology, growth rate, conidial yield, conidial germination and tolerance to UV light, were examined. Then, three isolates with better performance were selected for bioassays against the 4th instar larvae of H. cunea. Results: There were significant differences in colony growth rate, conidial yield, conidial germination and tolerance to UV light among the tested B. bassiana isolates. The isolates Bb22-2, Bb22-3 and Bb22-5 exhibited better characteristics with faster hyphal growth rate, higher spore production, faster spore germination and higher UV tolerance. The results of pathogenicity test of B. bassiana to the H. cunea larvae showed that the three isolates of B. bassiana demonstrated a higher efficacy. The three isolates caused the corrected mortality rates of 80%-90% in H. cunea at 11 d post inoculation. And the infection rates of B. bassiana against H. cunea were between 53% and 87% at 11 d post inoculation. The isolate Bb22-2 caused higher infection rates of H. bassiana against H. cunea than the other two isolates. Conclusion: This study demonstrated that B. bassiana is a highly effective entomopathogen against H. cunea. The isolate Bb22-2 has a great potential for sustainable control of H. cunea in forests. Further field experiments are needed to investigate its efficacy under natural conditions.