Beauveria bassiana delivered through a cellulose-based hydrogel is effective against the red poultry mite, Dermanyssus gallinae

Though the entomopathogenic fungus Beauveria bassiana has shown to be efficacious for managing Dermanyssus gallinae infestations, its delivery as liquid formulation poses concerns related to environmental stability and efficacy. To overcome such concerns, here we proposed a hydrogel matrix based on hydroxyethyl-cellulose (HEC) for delivering B. bassiana to control D. gallinae. Nymph and adult mites were exposed to a hydrogel matrix or filter papers containing B. bassiana (107 conidia/mL), with and without a pre-incubation period of 4 days at 25 °C (treated groups). As control groups, mites were exposed to hydrogel matrix or filter papers with sterile distilled water. Results showed higher mortality of all stages of D. gallinae in treated groups compared to respective control groups. The LT50 and LT90 estimated on D. gallinae were lower in treated groups (LT50 ≤ 9.5 days for adults; and LT50 ≤ 10.7 days for nymphs; LT90 ≤ 14.9 for adults; LT90 ≤ 17.9 days for nymphs) than in control groups (LT5 0 ≥14.9 days for adults, LT50 > 19 days for nymphs; LT90 > 20 days for adults and nymphs). Pre-incubation significantly reduced LT50 and LT90 with respect to other treated groups. Overall, our study outlined that the conidial suspension of B. bassiana in hydrogel is efficacious against both nymphs and adults of D. gallinae. The pre-incubation of B. bassiana in the HEC enhanced its efficacy. Thus, delivering B. bassiana through HEC-based hydrogel matrix may represent an effective and sustainable solution for managing D. gallinae infestations in the poultry industry.