Acaricidal activity of Cola nitida aqueous and ethanolic stem bark extracts against Otobuis megnini (Acari: Argasidae)

The present study was designed to evaluate, Acaricidal activity of Cola nitida aqueous and ethanolic stem bark extracts against Otobuis megnini Stem bark extracts of C. nitida were used for In-vitro adult immersion test of soft ticks. Three graded concentrations of the extracts, 15%, 30%, and 45% were tested at different time intervals and tick mortality was recorded for 48 hours. Dieldrin was synthetic acaricide used while distilled water was used as control. Standard procedures were applied to screen the phytochemical constituents of the tested plant part. The phytochemical screening of C.nitida stem bark revealed the presence of alkaloids , flavonoids , saponins , steroids , tannins and cardiac –glycoside. The LC50 and LC90 activity of ethanolic and aqueous extracts of stem bark of C. nitida soft ticks at different concentrations were estimated after 48 hours. Dieldrin has the lowest LC50 (0.34mg/ml) and LC90 (1.34mg/ml), followed by 45% ethanolic stem bark extract LC50 (0.71mg/ml) and LC90 (1.30mg/ml), while 15% concentration of ethanolic extracts of leaves has the highest LC50 (4.23mg/ml) and LC90(6.21mg/ml). At 24 hours both 45% ethanolic concentration of stem bark and dieldrin (5%) gave the same mortalities, 60+1.8 and 60+2.4 respectively. Aqueous extracts showed less acaricidal effects than ethanolic extracts. Ticks killing activity of all evaluated plant extracts increases with increasing exposure time and concentration as well.