Molecular analysis of rhizobacteria with insecticidal activity against potato pest <i>Tecia solanivora</i>

Rhizosphere bacteria, selected by plants for their diverse beneficial functions, have the potential to act as biocontrol agents due to their capability to infect and kill insect pests. One such pest, <i>Tecia solanivora</i>, poses a significant threat to potato crops in Central and South America. However, the capacity of rhizobacteria from potato crops to control <i>T. solanivora</i> remains unclear. This study aimed to evaluate the insecticidal capabilities of rhizobacteria against <i>T. solanivora</i>. Through phenotypic assays and genomic analysis, the virulence factors employed by the rhizobacteria in the infection process were characterised. Two rhizobacteria strains, <i>Enterobacter asburiae</i>, and <i>Raoultella terrigena</i>, exhibited significant insecticidal activity, causing 85% and 77% larval mortality, respectively. Genomic analysis revealed numerous virulence factors in both strains, including enzymes, antimicrobial compounds, volatile organic compounds, and toxins, which contribute to rhizosphere colonisation and the infection and killing of insect pests. Notably, the Tc toxin in <i>E. asburiae</i> and the SdiA receptor in <i>R. terrigena</i> were identified as the most significant virulence factors in these rhizobacteria. Comparative genomics showed that the virulence factors identified in this study are common among known insecticidal rhizobacteria, such as <i>Yersinia entomophaga</i> MH96 and various strains of <i>Pseudomonas</i>. These findings elucidate the infection mechanisms employed by <i>R. terrigena</i> and <i>E. asburiae</i> against <i>T. solanivora</i>, highlighting their potential as biocontrol agents for this pest. Rhizobacteria isolated from potato plants exhibited varying levels of insecticidal activity against <i>T. solanivora</i>.<i>Enterobacter asburiae</i> and <i>Raoultella terrigena</i> caused mortality rates exceeding 77% in <i>T. solanivora</i>.Genomic analysis revealed that insecticidal strains harbour specific genes that encode virulence factors for colonising, infecting, and killing insect pests.The Tc toxin is the main virulence factor in the <i>E. asburiae</i> genome.<i>Raoultella terrigena</i> improves insecticidal activity against <i>T. solanivora</i> by adding exogenous AHLs. Rhizobacteria isolated from potato plants exhibited varying levels of insecticidal activity against <i>T. solanivora</i>. <i>Enterobacter asburiae</i> and <i>Raoultella terrigena</i> caused mortality rates exceeding 77% in <i>T. solanivora</i>. Genomic analysis revealed that insecticidal strains harbour specific genes that encode virulence factors for colonising, infecting, and killing insect pests. The Tc toxin is the main virulence factor in the <i>E. asburiae</i> genome. <i>Raoultella terrigena</i> improves insecticidal activity against <i>T. solanivora</i> by adding exogenous AHLs.