In vitro acaricidal activity and phytochemical screening of Calotropis gigantea flowers against Riphicephalus microplus

Tick infestation particularly, of Riphicephalus microplus is a costly affair for farmers particularly in times of emerging resistance. Biological control using plant extracts will serve as environment friendly and cost-effective method. The present study was taken up to investigate the phytoconstituents and acaricidal activities of ethanolic extract of Calotropis gigantea flowers.

The acaricidal efficacy of ethanolic extracts of Calotropis gigantea flowers against engorged adult females of R. microplus were accessed by measuring mortality, inhibition of oviposition, hatching rate and larval mortality through Adult Immersion and Larval Packet Test. Gas chromatography-Mass spectrometry (GC-MS) analysis was done to reveal various compounds found in the flowers of Calotropis gigantea to justify their acaricidal activity.

As per the results of the in vitro tests (adult immersion test and larval packet test), there was adult mortality of 56.67%, RI of 0.17, IO of 66% and larval mortality of 60.33% at concentration of 100 mg/ml. LC₅₀ values were found to be 83.18 mg/ml. The GC-MS analysis revealed the presence of two major phytocompounds: dibutyl phthalate and n-Hexadecanoic acid in the extracts suggesting potential acaricidal properties. Results of the present study revealed the ethanolic extracts of Calotropis gigantea flower have potential anti-tick activity against both larval and adult stage of Rhipicephalus microplus.