AbstractBackgroundExisting treatments against poultry red mite (PRM;Dermanyssus gallinae) infestation have reduced efficacy or exhibit hazardous effects on chickens. Considering the economic importance of chickens, development of a safe and effective method for exterminating PRMs is necessary. Ivermectin and allicin are effective against some ectoparasites; however, their acaricidal efficacies against PRMs remain unknown.ObjectiveTo evaluate individual and combined efficacies of ivermectin and allicin in exterminating PRMs.MethodsDifferent concentrations (0.10–1.0 mg/mL) of ivermectin (1 mL) were applied via dropping method in different insect culture dishes (ICDs), prior to transferring PRMs. For the spraying method, PRMs were transferred to ICDs, before spraying ivermectin (1 mg/mL) solution (1 mL). Further, the acaricidal effect of allicin on PRMs was evaluated by applying different concentrations (0.25–1.0 mg/mL) of allicin (1 mL). The combined acaricidal effects of ivermectin and allicin were analysed using four concentration combinations. PRM death rates were determined after 2 h, 24 h, 2 days, 5 days and 7 days of drug application.ResultsIvermectin application (1 mg/mL) exterminated 64% and 100% of PRMs on 1 and 5 days, respectively, and prevented their revival. Further, 0.5 mg/mL ivermectin and 1 mg/mL allicin individually exterminated 98% and 44% of PRMs, respectively, within 7 days of treatment. In combination, 0.5 mg/mL ivermectin and 0.5 mg/mL allicin exterminated 100% of PRMs within 5 d of treatment. The most effective combination was 0.25 mg/mL ivermectin + 1.00 mg/mL allicin.ConclusionsThe efficacy of ivermectin–allicin combination in exterminating PRMs was demonstrated. This novel approach could be optimised for industrial applications.