Larvicidal and enzyme inhibition of essential oil from Spheranthus amaranthroids (Burm.) against lepidopteran pest Spodoptera litura (Fab.) and their impact on non-target earthworms.

The present investigation was highlighted the green-derived Essential oils with bio-active derivatives of Sphaeranthus amaranthoides (Sa-EO) can be employed in larvicidal and enzyme inhibitory effects against threatening tobacco cutworm S. litura and their detrimental effects against soil indicator earthworms. Chemical screening of EO-Sa using GC-MS exposed thoroughly five major derivatives with major peak area in d -Carvone (89.7%). The larvicidal activity of both third and fourth instar were improved steadily with higher dosage of treatments (400, 600, 800 and 1000 ppm). The lethal concentration (LC50) for third and fourth instar larvae was observed at 2.71 and 2.74 ppm (log dosage) respectively. Correspondingly, the sub-lethal dosage of EO-Sa (500 ppm) reduced the enzyme activity of Acid Phosphatase (ACP), Alkaline Phosphatase (ALP) and Adenosine triphosphate (ATP) significantly in both third and fourth instars. Further, the gut-histological activity of EO-Sa (500 ppm) against fourth instar showed damaged and disintegrated epithelial cells (EL) and columnar cells (CC), gut lumen (GL) and brush border membrane (BBM). Finally, the non-target screening against E. euginae showed that the EO-Sa was found to be harmless even at the maximum dosage of 1000 and 1500 ppm as compared to synthetic chemical monocrotophos in both filter paper test (FPT) and artificial soil test (AST). Thus the present investigation evidenced that active phyto-chemistries of EO-Sa delivers a sturdy toxicological response against S. litura and harmless against non-target earthworm. [ABSTRACT FROM AUTHOR]