Identification of insecticidal molecule aucubin from Metarhizium anisopliae ethyl acetate crude extract against disease mosquito vector

Abstract

Identification of insecticidal compounds from the entomopathogenic fungus Metarhizium anisopliae crude extract was performed by TLC and column fractionation. From the fractionation four fractions were separated and tested for larvicidal, pupicidal and adulticidal potential against Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus mosquitoes. Among the four fractions the fraction-3 was most effective against larvae with LC50 values, 1.238, 1.300 and 2.899 for pupae, 1.440, 1.657, 2.593 and adult, 1.988, 2.037 and 4.086 µg/ml against Ae. aegypti, An. stephensi and Cx. quinquefasciatus at 24 h post treatment respectively. The effective fraction-3 were charectrized through FT-IR, UV–Vis spectroscopy, 13C-NMR and 1H-NMR, HPLC, and LC–MS analysis allowed to identifying the effective compound in fraction-3. Overall, the results confirmed the use of the fungus derived molecules as an active green pesticide against mosquito vectors of public importance and led to the identification of highly effective mosquitocidal products. In particular the toxic activity of aucubin far encompassed that of the large majority of earlier studied microbial insecticides, making this molecule an ideal candidate for the development of insecticides in the “real world”.