Acaricidal activity of Juglans regia hull extracts against unfed larvae of Rhipicephalus microplus ticks

The walnut (Juglans regia) hull extracts in three different solvents (acetone, chloroform and ethanol) were tested against unfed larvae of Rhipicephalus microplus ticks using larval immersion test. Mortality rates of larval ticks were in dose-dependent manner. The 100% mortality of larvae was achieved at 10% concentration for acetone and chloroform extracts whereas ethanolic extract showed 100% mortality of tick larvae from 7.5% concentration onwards. The LC50 values of 1.52, 1.22 and 1.43% were determined for chloroform, acetone and ethanolic extracts, respectively. However, the lowest LC95 value was calculated for ethanolic extract indicating its better acaricidal activity. Significant larvicidal activity of J. regia hull extracts against tick larvae qualifies them as green pesticides which could be combined with other tools for integrated pest management.