Synergistic acaricidal activity of Beauveria bassiana TU-33 and biosynthesized silver nanoparticles against the camel tick Hyalomma impeltatum (Acari: Ixodidae)

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Tick pest management requires innovative approaches to overcome problems caused by the excessive use of synthetic pesticides, including resistance and environmental pollution. The use of biological agents and biosynthesized nanoparticles offers a promising alternative, reducing residue concerns while effectively controlling tick populations. The current study aimed to evaluate the synergistic effects of locally entomopathogenic fungus (EPF), Beauveria bassiana and silver nanoparticles (AgNPs) on camel tick, Hyalomma impeltatum. B. bassiana was isolated from soil millipede, Archispirostreptus syriacus and molecularly identified (sequence analysis of ITS1 and ITS4). The acaricidal effectiveness of B. bassiana conidial suspension (CS) or fungal filtrates (FF) along with AgNPs at four concentrations was separately and jointly evaluated against eggs, larvae, and females of H. impeltatum using immersion test. The percentage of larval hatchability was recorded 7 days post-treatment, whereas mortality of larvae and females was monitored daily for 4 days. The isolated fungus was identified as B. bassiana TU-33. All tested combinations showed synergistic effects against H. impeltatum eggs, larvae, and engorged females. Three days after exposure to a conidial suspension (1.5 × 10⁵ conidia/mL) combined with AgNPs (2 mg/L), complete mortality was observed, with LC₅₀ values of 0.20 mg/L for larvae and 0.22 mg/L for engorged females. At the highest conidial dose (1.5 × 10⁷ conidia/mL), egg hatchability decreased to 31.7%, while larval and female mortality reached 82.2% and 71.5%, respectively. All biological traits of engorged females were significantly altered, demonstrating the high efficacy of combining EPF with AgNPs for tick control.