In vitro efficacy and field effectiveness of silica-based acaricide against Dermanyssus gallinae.

Objective: The poultry red mite, PRM, Dermanyssus gallinae (D. gallinae), is one of poultry's most important and common pests. Although the presence of a variety of acaricides in control, PRM continues to be frequently reported around the world, owing to the developing resistance and severe legislation prohibiting the use of chemicals. Therefore, new and safe control approaches that do not threaten animal and human health are required. This study is aimed to determine the efficacy of a natural silica-based product based on diatomaceous earth (DE) in-vitro conditions and its combination with locally applicated synthetic pyrethroids under field conditions in commercial egg-laying henhouses. Methods: Dermanyssus gallinae populations were collected and transferred alive to the laboratory from integrated cage poultry farms. The bioassays were performed with the liquid formulation of silicon dioxide. The LT50 values were calculated by probit analysis using PoloPlus-PC software. The field treatment was conducted using the combination of silicon dioxide and alpha-cypermethrin in two commercial poultry houses with natural PRM infestation. After application, mites were collected with PVC traps on different days. The traps were individually packed and the number of mites was counted under a stereo microscope in the laboratory. The efficiency of the application was then determined by counting the mites under a stereomicroscope. Results: In laboratory conditions, DE active substance at the concentration of 320 mg/dish eventually reach 100% mortality of D. gallinae and the mean LT50 values were determined as 26.42±0.57 h. The combination of silicon dioxide and alpha-cypermethrin in field conditions was found to be highly effective in reducing the number of PRMs and its effects lasted for four months following treatment. Conclusion: These results suggest that DE might offer an environmentally-friendy alternative in PRM control on its own or in combination with widely used synthetic pyrethroids. [ABSTRACT FROM AUTHOR]