Bioefficacy potential of terpenoid extract of Zanthoxylum nitidum root against Aedes aegypti and Aedes albopictus

Essential oil of different species of Zanthoxylum possesses mosquitocidal efficacy. Often, synergistic effects of natural molecules exhibit greater efficacy than individual compound(s). Therefore, we examined the bioefficacy of terpenoid and phenolic fractions of root extracts of Zanthoxylum nitidum against dengue vectors, Aedes aegypti  Linnaeus, and Aedes albopictus Skuse. The LC50 of ethanolic root extract against 4^th instar larvae was 45.89 and 39.56 ppm against Ae. aegypti and Ae. albopictus at 24hr, and 10.88 and 21.52ppm at 48hrs post-treatment, which was significantly lower than the LC50 concentration of extract of Azadirachta indica used as a positive control. The LC50 of terpenoid fraction of the root extract for larval mortality was 205.07 and 336.24ppm against Ae aegypti and Ae albopictus, respectively. The LC50 for phenolic fraction against Ae. aegypti was 176.79ppm.But the LC50 dose also caused  46-75% adult emergence inhibition (EI) . The EI 50   increased developmental period, decreased adult life span, fecundity, and fertility. Flash chromatographic separation of the terpenoid extracts yielded four fractions, out of which the fraction RT1 gave the lowest LC50 of 117.21 ppm against Ae.aegypti, and  291.17ppm against Ae. albopictus. The study reveals important information about using the root of Z. nitidum for the control of dengue vectors.

Key Words: Zanthoxylum root; Aedes aegypti, Aedes albopictus, Terpenoids.