Bioactive molecules derived from Scoparia dulcis medicinal flora: Act as a powerful bio-weapon against agronomic pests and eco-friendlier tool on non-target species

Abstract

An eco-friendly approach to pest management is being investigated in this study, and it involves the utilization of bioactive molecules isolated from the Scoparia dulcis medicinal plant. We performed acute toxicity against agronomic pests such as Spodoptera litura, Helicoverpa armigera, and Plutella xylostella. In addition, the bio-toxicity and suitability index tests on non-target terrestrial fauna, such as Aemula aemula, Crocothemi servilia, and Paracopris cribratus. Bioactive molecule identification was made by using GC–MS and FTIR analysis. For ovicidal activity, fresh eggs of S. litura, H. armigera, and P. xylostella were tested at 2 µg/ml to 200 µg/ml. At 24 hrs. post-treatment with S. dulcis, aqueous leaf extract and major bioactive molecules were used for egg mortality. In larvicidal activity, 3rd instar larva of the target species was tested at 4 µg/ml to 250 µg/ml (wide and narrow range test). Overall mortality was examined using probit analysis to calculate LC50/LC90. Moreover, we examined the toxicity of S. dulcis aqueous leaf extract and identified major bioactive molecules at doses ranging from 300 µg/ml to 25,000 µg/ml on non-target terrestrial fauna with construct suitability index. In total, 15 bioactive molecules were identified through GC–MS analysis providing 100% confirmation and in which three major bioactive molecules were identified: 1,4-Benzenedicarboxylic acid, bis(2-ethylhexyl) ester (25.17%), 1,2-Benzenedicarboxylic acid (23.29%), and 6-Octen-1-ol, 3,7-dimethyl- (10.21%). FTIR spectral analysis was used to identify functional groups. At a concentration of 10 µg/ml, the ovicidal activity of 1,4-Benzenedicarboxylic acid, bis(2-ethylhexyl) ester showed more than 90% against S. litura, H. armigera, and P. xylostella, respectively. Among the many phyto-products evaluated for larvicidal action, 1,4-Benzenedicarboxylic acid, bis(2-Ethylhexyl) ester exhibited the highest larval toxicity against S. litura, H. armigera, and P. xylostella, with LC50 values of 7.55, 9.50, and 12.89 µg/ml. However, the same phyto-products had no negative impact on non-target terrestrial species (A. aemula, C. servilia and P. cribratus). The major bioactive molecules provided spectacular toxicity towards pests and eco-safety on terrestrial non-target fauna.