Evaluation of acaricidal activity in entomopathogenic fungi for poultry red mite (Dermanyssus gallinae) control

The poultry red mite (PRM), Dermanyssus gallinae, significantly impacts the health of egg-laying hens. Mites feed on the blood of infested chickens and have a great economic impact on the poultry industry. Chemical treatment of mites raises concerns about their resistance to miticides and residues in eggs and poultry. Biocontrol using entomopathogenic fungi is expected to be a chemical-free strategy for reducing PRM infestations. Therefore, the present study aimed to investigate the effects of various entomopathogenic fungal species collected in South Korea on the inhibition of PRM. Seventeen strains of six fungal species collected from various sources were used to evaluate acaricidal activity against PRM. The results showed that 16/17 strains had acaricidal properties against PRM, of which strains of Metarhizium anisopliae had the highest acaricidal activity. Mites treated with M. anisopliae CBNU 4-2 showed 100 % mortality 5 d after inoculation, followed by M. flavoviride var. pemphigi. The M. flavoviride var. pemphigi CBNU 1-1-1 showed 97.78 % mortality after 10 d of exposure to fungi. The mortality rate of PRM treated with other strains slowly increased and reached its highest value on the 14th day of inoculation. The results of this study provide information on the acaricidal activity of different entomopathogenic fungi against PRM. This information is important for the selection of fungal species for developing biocontrol methods for PRM treatment. These strains could be used for further evaluation of PRM treatment on chicken farms, or in combination with other methods, to increase PRM treatment efficiency.