Entomopathogenic effect of Beauveria bassiana on Phlebotomus perniciosus (Diptera: Psychodidae)

Phlebotomus perniciosus (Diptera: Psychodidae) is the primary vector of Leishmania infantum and several phleboviruses in the Mediterranean Basin. Chemical insecticides (e.g., pyrethroids) remain the only effective tool for controlling sand fly populations and preventing transmission of vector-borne pathogens. However, their use raises concerns due to environmental and food contamination as well as development of insecticide resistance, advocating alternative control strategies such as the use of entomopathogenic fungi (EPF). For example, Beauveria bassiana has shown efficacy against several arthropod species, including mosquitoes, ticks and mites, though, no studies yet have been conducted on P. perniciosus. In this study we evaluated the pathogenicity of a native strain of B. bassiana on the egg hatching rate and developmental stages of P. perniciosus, conducting all experiments in triplicate. Eggs, first instar larvae, and gravid adult females of this sand fly species were exposed to different conidial concentrations of B. bassiana (1-5 × 10⁵, 1-5 × 10⁷, and 1-5 × 10⁹ conidia/mL). Control group was treated with distilled water containing 0.1% Tween 80. Beauveria bassiana inhibited egg hatching at the highest conidial concentration and all three concentrations reduced the lifespan of adult females by approximately half compared with control females. Infected females also laid significantly fewer eggs (5.9 ± 1.1 eggs per female) than control ones (30.4 ± 3.4 eggs per female). In contrast, larvae demonstrated low susceptibility to fungal infection. Overall, these results demonstrate the strong negative effect of B. bassiana exposure on P. perniciosus, highlighting its potential as a biocidal agent and contributing to the development of new strategies to suppress sand fly populations and reduce transmission of vector-borne pathogens.