Bacterial endophytes from Chukrasia tabularis can antagonize Hypsipyla robusta larvae

Damage by the shoot-tip borer Hypsipyla robusta (Lepidoptera: Pyralidae) has limited the commercial cultivation of Chukrasia tabularis (Meliaceae) in many parts of the world. Recently, a number of C. tabularis families in Vietnam have shown field resistance to H. robusta. This study explores whether endophytic bacteria in C. tabularis can inhibit the development of H. robusta. Endophytic bacteria from resistant trees had strong repellent (73–97%) and antifeedant (74–84%) activity with H. robusta in laboratory trials. The most biologically active isolates were identified as Bacillus bombysepticus (4 isolates) and Bacillus velezensis (2 isolates) based on phylogenetic analysis of 16S rRNA, gyrB, pycA and rpoB. Fifteen days after releasing H. robusta larvae in a nursery trial, spray inoculation with bacterial solutions from resistant trees reduced shoot tip damage by over 60% compared with the control. Spray treatments with bacterial endophytes from susceptible trees were less effective. These findings have application to the future development of biological control of H. robusta, and the selection of resistant trees for breeding.

DOI/link: https://doi.org/10.1007/s12600-022-01001-6