Biocontrol of Phenacoccus solenopsis Tinsley using entomopathogenic fungi and bacteria.

Introduction: Phenacoccus solenopsis Tinsley, poses a significant threat to a range of crops worldwide. This study aimed to evaluate the efficacy of entomopathogenic fungi (Alternaria murispora and Alternaria destruens) and bacteria (Streptomyces bellus-E23-2) against adult females of P. solenopsis under laboratory (26 ± 2°C) and greenhouse conditions. Methods: Laboratory trials tested A. murispora, A. destruens (10⁴-10¹⁰ conidia mL^-1), and S. bellus E23-2 (10⁴-10¹⁰ cfu mL^-1), alone and in combination, recording mortality rates and LC₅₀ values. Greenhouse trials tested the best lab treatments on infested potato plants, monitoring pest density and plant quality. Results and discussion: In laboratory trials, A. murispora at 1010 conidia mL^-1 was the most effective, achieved 79.7% mortality (LC₅₀ = 1.338 x 10⁸ conidia mL^-1 after 14 days). Combination treatments significantly enhanced efficacy, with A. murispora + S. bellus E23-2 (10¹⁰ conidia mL^-1 + 10¹⁰ cfu mL^-1) reaching 85.3% mortality. In greenhouse trials, the combination treatments notably reduced P. solenopsis densities and increased the number of infected mealybugs, with A. murispora + S. bellus E23-2 being the most effective. These treatments did not harm plant quality, unlike imidacloprid, which reduced visual quality despite its high efficacy. Alternaria murispora and S. bellus E23-2 effectively control P. solenopsis, providing a sustainable, plant-safe alternative to chemical insecticides. [ABSTRACT FROM AUTHOR]