Biocontrol of Phenacoccus solenopsis Tinsley using entomopathogenic fungi and bacteria

Abstract

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 × 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.