Insecticidal effects of Parthenium hysterophorus and Moringa oleifera leaf extracts on digestibility indices and survival of Spodoptera litura (Lepidoptera: Noctuidae)

Abstract

Insecticidal properties of Parthenium hysterophorus L. (family: Asteraceae), an annual herb, and Moringa oleifera (Lam.) (family: Moringaceae), a perennial tree, were assessed against different digestibility parameters and survival rate of Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae). Effect of different extracts (based on three extraction solvents: ethanol, methanol, and acetone) of P. hysterophorus and M. oleifera on the digestibility indices and larval mortality of Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae) were studied. The extracts were tested at two different concentrations; 25 mg and 50 mg. The effect of methanol extract on S. litura larvae was greater than that of ethanol and acetone. The methanol extract of P. hysterophorus at 50 mg concentration significantly reduced the digestibility indices; 49.6% consumption rate, 80.4% growth rate, 63.9% efficiency of conversion of ingested food, 68.4% efficiency of conversion of digested food, 39.3% assimilation rate, and 12.3% approximate digestibility of S. litura larvae compared with the control (positive untreated) treatment. By using methanol extracts of P. hysterophorus at 50 mg concentration, larvae’s survival rate was also found to be lower than those of other treatments. The performance of M. oleifera extracts was lower in terms of affecting the digestibility and survival of S. litura compared to P. hysterophorus. Among the two plant extracts, a higher concentration (50mg) of P. hysterophorus using methanol as a solvent represented a promising natural product for S. litura control.