Bio-efficacy of chloroform crude extracts of chick weed Ageratum conyzoides (Linn.) against the tobacco cutworm Spodoptera litura (Linn.) and their non-toxicity against the beneficial earthworm

The current study investigates the phyto-chemical screening of chloroform crude extracts of chickweed Ageratum conyzoides (Linn.) (Cm-Ac) and their target and non-target toxicity against the pest Spodoptera litura and beneficial earthworm. Phyto-chemical characterization of Cm-Ac over GC-MS technique revealed thirty four bioactive compounds with highest peak area% observed in Phenol, 2,4-Bis-(1,1-Dimethylethyl)-(6.340 PA%), followed by n-Hexadecanoic acid (5.95 PA%) and 1-Octadecene (5.94 %) respectively. Larval toxicity was observed maximum at the dosage of 1000 ppm at second instar (98.23 %) as compared to other dosages. Lethal dosage (LC50) obtained on 2.467 log ppm respectively. The sub-lethal toxic dosage of Cm-Ac (100-500 ppm) displayed adverse impact on larval-pupal growth and development in dose dependent manner. Also, the sub-lethal dosage of Cm-Ac also decreased the level of mid-gut enzymes in dose dependent manner. The mid-gut tissues including Gut Lumen-(GL), Epithelial Layer-(EL), and Brush Border Membrane-(BBM) severely affected at the prominent concentration of 500 ppm as paralleled with control. Non-target activity against Eudrilis eugeniae revealed that the Cm-Ac treatment is less toxic at the prominent concentration of 1000 ppm as paralleled to Cypermethrin treatment. Overall, the current results are promising in developing botanical based insecticides which are biodegradable and importantly harmless or less toxic to the non-target earthworms.