COMPARATIVE EVALUATION OF ACARICIDAL PROPERTIES OF Datura stramonium and Datura metel
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Date
2020
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AAU, Jorhat
Abstract
Ticks are group of arthropod vectors that not only cause disease but also transmit diverse pathogens that affect human and animal health. Indiscriminating use of synthetic acaricides have led to development of acaricide resistance in ticks. Several plant secondary metabolites are known to exhibit toxic affect on insects. Phyto-extracts are also environmentally friendly and have thus become attractive alternative in insect management strategies. Datura has long since been used in folklore medicine and is reported to have other pharmaceutical uses. My research involved the use of two different species of Datura, viz., D. stramonium and D. metel that grow abundantly in the North East India especially, in Assam. The two species of Datura were collected from different locations of Jorhat district and evaluated for their acaricidal properties. Chemo-profiling of both the plant species revealed the presence of some phyto-metabolites with known biocidal properties, more specifically acaricidal properties. Saponin, Flavonoids, Tannins, Phlobatannins and Steroids were analyzed in both the species and revealed that except for Saponin all others metabolites were present in both the species of Datura. Atropine and Scopolamine earlier reported for their acaricidal activity were assayed using HPTLC technique. Shoots of D. stramonium showed the presence of Atropine (0.04238%) and Scopolamine (0.21554%) whereas; the presence of Scopolamine (0.00754%) was detected only in the roots. Presence of Atropine (0.08083%) only was detected in shoots of D. metel. The variation in Atropine as well as Scopolamine in roots and shoots of the same plant species might be due to variance in tissue specific concerned gene(s) expression, and among the different species might be due to genetic variation or variation in eco-geographical conditions which are yet to be explored. Acaricidal properties of both the plant species were assayed in terms of LC50 as well as Inhibition in Oviposition (IO%) against a tick line of Rhipicephalus microplus collected from Assam. Between the two plant species, D. metel showed lower LC50 (6.37%) than D. stramonium (12.27%). In case of IO also, more IO value (76%) was observed in D. metel than D. stramonium (35.27%). The lower LC50 and higher IO values indicate that D. metel has more acaricidal potential than D. stramonium. Findings from the study also showed that shoots of D. stramonium contains both Atropine (0.04238%) and Scopolamine (0.21554%) whereas, D. metel-shoots contain only Atropine (0.08083%) and it is almost double of what D. stramonium contains. The present study indicates that Atropine may be directly associated with acaricidal activity with little or no role of Scopolamine. Although, the study did not involve the analysis of other compounds, their involvement in acaricidal activity cannot be denied. This research can be extended further to explore specific metabolites having acaricidal properties present in other plant systems including Datura for the better and greater interest of development of plant based-based acaricides/insecticides.