STUDY ON IN VITRO LOUSCIDAL AND ACARICIDAL PROPERTIES OF CALPURNIA AUREA, OTOSTEGIA INTEGRIFOLIA, NICOTIANA TABACCUM AND JATROPHA CURCAS AGAINST BOVICOLA OVIS AND AMBLYOMMA VARIEGATUM
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2015-06
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Abstract
The present study was designed to evaluate the preliminary phytochemicals present in methanolic leaf extracts of Calpurnia aurea, Otostegia integrifolia, Nicotiana tabaccum and petroleum ether seed oil extract of Jatropha curcas and to assess their in vitro louscidal and accaricidal efficacy. Accordingly, each plant was subjected to qualitative phytochemical screening for the presence or absence of secondary metabolites such as alkaloids, steroidal compounds, phenolic compounds, flavonoids, saponins, tannins, phlobatannins, triterpens and glycosides using standard procedures. The four selected medicinal plants and a commercially used acaricide (0.1% diazinon) were examined for their louscidal and acaricidal activity against B. ovis and A. variegatum at different time intervals using the in vitro adult immersion test at concentrations of 200, 100, 50, 25, 12.5 and 6.25 mg/ml. The findings revealed that extracts of C. aurea leaf and J. curcas seed oil caused high mortalities of B. ovis at all concentrations with no significant difference from the activity of 0.1% diazinon ( > 0.05) within 24 hours of exposure. Moreover, at 200 mg/ml concentration, crude extracts of N. tabaccum and O. integrifolia produced 93% and 63% mortality respectively against B. ovis within 24 hours of exposure. The extracts of all four plants were also examined for their acaricidal activity against A. vareigatum. Although, the effects of the extracts on this tick species was much lower than what was observed on lice, the extracts of C. aurea leaf and J. curcas seed oil have shown 56% and 39% mortality at 200 and 100 mg/ml concentrations, respectively within 24 hrs exposure of the parasite and was comparable to the acaricidal activity of 0.1% diazinon ( > 0.05). A similar situation was caused by crude extracts of N. tabaccum which was 44% and 39% mortality at concentrations of 200 and 100 mg/ml within 24 hrs of exposure, respectively. However, O. integrifolia showed significantly lower acaricidal activity ( < 0.05) when compared to the reference drug (0.1% diazinon). The current study revealed that crude extracts of C. aurea leaf and J. curcas seed oil have strong louscidal activity. Moreover, crude extracts C. aurea and J. curcas showed high mortality at lower concentrations and can be used as a potential alternative to synthetic acaricides to control B. ovis infestations. Though, they are not effective at lower concentrations, crude extracts of C. aurea, N. tabaccum and J. curcas seed oil had better acaricidal effects on cattle ticks at higher concentrations. This is a promising finding to have an alternative means of treatment to substitute the use of synthetic drugs which have a widespread drug resistance especially in developing countries including Ethiopia.
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Therefore, further investigation should be made on their safety and in vivo efficacy as well as cost effectiveness of the products that exhibited strong louscidal and acaricidal activity with a view of substituting the conventional synthetic acaricides.
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MSc Thesis
Keywords
Bovicola ovis, Amblyomma variegatum, Medicinal plants, Mortality, phytochemical screening