Identification of Specific Virulence Factors of Pseudomonas Strains in the Biocontrol of the Potato Pest Tecia solanivora

Abstract

Tecia solanivora (The Guatemalan potato tuber moth) is a major potato pest, responsible for up to 20% of crop losses and a significant economic impact. Certain Pseudomonas exhibit insecticidal activity and produce virulence factors with cytotoxic and antimicrobial properties, positioning them as promising candidates for biological control. This study evaluated seven Pseudomonas strains with insecticidal activity and identified key virulence factors involved. The strains demonstrated varying degrees of insecticidal activity, with Pseudomonas protegens strains CHA0 and 59C being the most lethal, causing over 75% mortality and triggering a systemic melanization response in the insects. Genomic analysis revealed 175 virulence-related genes shared across all strains and 16 genes specific to the highly insecticidal ones, including genes for antimicrobial compounds and insect toxins. Mutational analysis confirmed the roles of hydrogen cyanide, 2,4-diacetylphloroglucinol, pyoluteorin, Fit toxin, and two-partner secretion systems in P. protegens CHA0 insecticidal activity. This strain also exhibited insecticidal effects on adult T. solanivora and delayed egg hatching and pupal emergence. In microcosm assays, P. protegens CHA0 reduced tuber damage caused by T. solanivora larvae by up to 38%. These results suggest that P. protegens CHA0 is a promising biocontrol agent, providing a sustainable alternative to chemical pesticides to control T. solanivora.