Acaricidal activity of neem oil against Sarcoptes scabiei var.cuniculi larvae in vitro

Sarcoptes scabiei var.cuniculi larvae were placed into small polystyrene petri dishes,and different concentration of paraffin solution of neem oil was directly added into them.500g/L pyrethrins and 25g/L avermectin were used as treated control,while distilled water and paraffin oil represented untreated control.The number of dead mites was examined at different time points,and the mortality,median lethal time(LT50) and median lethal concentration(LC50) were used to evaluate the acaricidal activity of neem oil against S.scabiei var.cuniculi larvae in vitro.The undiluted neem oil killed all larvae in 25min.The acaricidal activity of the undiluted neem oil was significantly higher than that of 500g/L pyrethrins(825min,P0.01),but not significantly different from that of 25g/L avermectin(19min,P0.05).The LT50 values of 500,250 and 125mL/L neem oil against S.scabiei larvae were 1,2 and 5h,respectively.The LC50 and LC95 values were 2.908 and 12.018mL/L 24 hours post-treatment,respectively.These results demonstrated that the neem oil had good effect against S.scabiei var.cuniculi larvae in vitro.