Biopesticidal Potential of Lippia javanica (Burm. F) Spreng. Leaf Extracts and their Fractions against Spodoptera litura (Fab.)
M. Pavunraj *
Post Graduate and Research Department of Zoology, Vivekananda College, Tiruvedakam West, Madurai District, 625 234, India.
P. Ezhumalai
Department of Zoology, Dwaraka Doss Goverdhan Doss Vaishnav College, Chennai, 600 106, India.
K. Nagarajan
Department of Animal Science, Manonmaniam Sundaranar University, Tirunelveli, 627 012, India.
P. Murali
Department of Zoology, N.M.S. S. Vellaichamy Nadar College, Nagamalai, Madurai, 625019, India.
S. Rajeshkumar
Nanobiomedicine Lab, Centre for Global Health Research, Saveetha Medical College and Hospitals, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai, 602 105, India.
*Author to whom correspondence should be addressed.
Abstract
Three organic solvent extracts of Lippia javanica leaves were screened for their antifeedant and larvicidal activities against the 4th instar larvae of Spodoptera litura at 5% concentration. The maximum antifeedant and larvicidal activities were recorded in ethyl acetate extract (76.57%) for antifeedant and (90.40%) for larvicidal activity, followed by chloroform and hexane extracts. Ten fractions were obtained from the ethyl acetate extract of L. javanica by using different combinations of hexane and ethyl acetate as the mobile phase through column chromatography. The fractions were screened at 1000 ppm concentrations for antifeedant and larvicidal activities. Fraction 10 (71.75%) was found to be the most effective one, followed by fraction 4 (61.32%) and fraction 7 (60.58%) for antifeedant acitivity. At a 1000 ppm concentration, fraction 3 exhibited the highest larvicidal activity (79.20%) against S. litura, followed by fraction 1 (76.0%), while fractions 5 and 6 have shown equal activity. Quantitative protein analysis revealed that treatment with the eighth fraction reduced the haemolymph protein drastically (1.52 mg/mL) compared to control (2.84 mg/mL) and other fractions. In the reference control azadirachtin treatment, the haemolymph protein quantity was found to be nearly the same (1.4 mg/mL) as that of the eighth fraction. Treatment with the first and second fractions resulted in increased haemolymph protein (8 and 7.6 mg/mL, respectively). The bio-efficacy of L. javanica in pest management is discussed.
Keywords: Antifeedant, larvicidal activity, Lippia javanica, Spodoptera litura, plant extracts, environmentally friendly bio-pesticide