Toxicity and lethal effects of herbaceous plant crude extracts against Spodoptera litura

Abstract

Abstract Background Tobacco caterpillar, Spodoptera litura, attacks various cultivated plants and causes significant yield losses. In this study, an eco-friendly approach like using botanical insecticides was adopted to examine the toxicological effect of six herbaceous plants (Phyllanthus niruri, Cyperus rotundus, Euphorbia hirta, Boerhavia diffusa, Parthenium hysterophorus and Cynodon dactylon) against S. litura. Results Six herbaceous plants crude extract showed a definite level of toxicity against S. litura larvae (3rd instar) using the surface diet contamination method. Among tested herbaceous plants crude extract at 5 μg/ml concentration, C. dactylon showed significant high larval mortality (75%) against S. litura larvae compared to P. niruri (39%), C. rotundus (36%), P. hysterophorus (26%), B. diffusa (22%) and E. hirta (22%) treatments. A cent percent S. litura larval mortality was achieved at lower concentration from crude extract of C. dactylon (11.2 μg/ml) compared to E. hirta (18.6 μg/ml), B. diffusa (24.39 μg/ml), P. hysterophorus (31.4 μg/ml) crude extracts. The lethal concentration (LC50) of C. dactylon, P. hysterophorus, C. rotundus, P. niruri, B. diffusa and E. hirta crude extracts was estimated to be 1.45, 4.09, 5.74, 6.75, 10.92 and 13.62 μg/ml, respectively. Conclusion The study results suggested that C. dactylon crude extract possesses the potential to reduce the S. litura damage on crops as a natural alternative to the chemical insecticides with no toxicity to beneficial species.

Keywords

• Cynodon dactylon
• Discriminating dose
• Ethyl acetate
• Insecticidal
• Larvicidal