Isolation, characterization and virulence of Beauveria bassiana strain SPT35 against the wood-boring beetle, Aromia bungii.

Abstract

Background: Aromia bungii (Coleoptera: Cerambycidae) is a major wood-boring pest of rosaceous fruit trees, whose distribution and impact have expanded considerably in recent years. Conventional chemical control methods often cause environmental pollution, harm natural enemies and compromise fruit safety.

Results: In this study, an entomopathogenic fungal strain was isolated and purified from a mummified larva of A. bungii. Based on morphological characteristics and molecular identification, the fungus was identified as Beauveria bassiana and designated as SPT35. The SPT35 strain showed a daily radial growth rate of 3.95 mm/day on SDAY medium at 30 °C. By the tenth day of cultivation, the sporulation yield per unit area and total sporulation yield reached 5.15 × 10⁸ spores/cm² and 6.31 × 10⁹ spores/Petri dish respectively. The virulence of SPT35 against both larvae and adults of A. bungii increased with conidia suspension concentration. At 1 × 10⁷ spores/mL, the cumulative corrected mortality rates for first- to third-instar larvae after 10 days reached 95.83%, 100% and 95.24%, respectively, with lethal concentration (LC₅₀) values of 7.19 × 10², 1.51 × 10⁴ and 1.35 × 10⁵ spores/mL. For adults, the cumulative corrected mortality exceeded 50% after 8 days across the tested concentrations, with an LC₅₀ ranging from 2.45 × 10⁷ to 3.84 × 10⁷ spores/mL. In field trials, trunk injection treatment with the SPT35 strain at a concentration of 1 × 10⁸ spores/mL achieved a control efficacy of 88.93% after 7 days.

Conclusions: The SPT35 strain can serve as an effective microbial agent for controlling A. bungii and holds potential for development into a biocontrol product for practical application. © 2026 Society of Chemical Industry.