Study on ethnobotany, phytochemistry, toxicity and effectiveness of herbal remedies against Boophilus decoloratus in Suba, Kenya

Abstract

Abstract. Onyango AO, Kokwaro JO, Onyango DW, Yusuf AO. 2019. Study on ethnobotany, phytochemistry, toxicity and effectiveness of herbal remedies against Boophilus decoloratus in Suba, Kenya. Asian J Ethnobiol 2: 38-50. Plants have been found to have a variety of biological activities against insect pests, some of which have been confirmed. The ethnobotany, phytochemistry, toxicity, and acaricidal behavior of crude extracts of three selected plants against blue-tick in Suba Sub-County, Kenya, were investigated as part of this study. In Suba Sub-County, a total of 32 herbalists, ranging in age from 28 to 87, were interviewed using a questionnaire about their knowledge of acaricidal plants. The area’s name, a component used, conventional planning, and administration methods were all recorded. The number of medicinal plant citations was highly correlated with the informants’ age. Based on independent researches (IR), the study described 16 plants distributed among 13 families. For phytochemical tests, Phytolacca dodecandra, Cissus quadrangularis, and Ipomoea kituiensis were collected and extracted in methanol, dichloromethane (1:1 v/v), and distilled water separately. Terpenoids, tannins, saponins, flavonoids, and alkaloids were all present in the three plants, except flavonoids, which were absent in P. dodecandra.To test the efficacy of crude extracts of these selected plants, larvae of the Boophilus spp., the tick was used in an in vitro acaricidal activity analysis. The effects of 2.5, 5, and 10 mg/mL concentrations of water and methanol in DCM (1:1 v/v) crude extracts of P. dodecandra (leaves), C. quadrangularis (whole), and I. kituiensis (leaves) were compared to that produced by the standard reference acaricide, almatix® (12.5 percent amitraz) as a positive control. The extracts' activity against larvae was tested, and the extracts were most active at 10 mg/mL concentration. The death rate was determined within 24 hours. The extracts of Cissus quadrangularis (100 kills at 10 mg/mL) and P. dodecandra (100 kills at 5 and 10 mg/mL) was the most potent compared to almatix, while I. kituiensis methanol/DCM (1:1v/v) extract was the least potent. The variance analysis revealed significant differences in the acaricidal activity of plant extracts at all concentrations tested (2.5, 5, and 10 mg/mL) (P?0.05). The LC50 of Boophilus decoloratus larvae was determined if methanol: DCM (1:1 v/v) extracts of I. kituiensis showed mild toxicity, whereas those of P. dodecandra and C. quadrangularis showed high toxicity. This study concluded that C. quadrangularis (whole), I. kituiensis (leaves), and P. dodecandra (leaves) extracts are acaricidal and as potent at high concentrations as almatix. The mortality of the larvae increases with increasing extract concentration, indicating that the extracts of the top three study plants are effective in blue-tick control. It is recommended that isolate and purify crude compounds, and bioassay of these isolated compounds be performed on the same blue-tick larvae to achieve highly efficacious conventional acaricides.