Effects of β-sitosterol on growth, development and midgut enzymes of Helicoverpa armigera Hübner

Abstract

Helicoverpa armigera is a global agricultural pest of serious concern. Continued use of chemical insecticides as control measures has raised grave health and environment concerns, necessitating a search for botanicals as safe alternatives. The current study investigates the effects of ?-sitosterol, a bioactive phytocomponent in Thevetia neriifolia, on the growth and development, as well as on midgut enzymes of H. armigera. Dietary ?-sitosterol produced dose-dependent systemic toxicity and growth inhibitory effects in H. armigera; the most significant effects were obtained with 10 ?g/mL dietary ?-sitosterol. Higher prepupal and pupal mortality in comparison to larval mortality and a comparatively greater reduction in average weight gained by later instars point to cumulative effects of ?-sitosterol. The delayed effects were ascertained by the 82.05%-57.89% reduction in adult emergence in comparison to 95.02% emergence in controls. Dose-dependent effects of ?-sitosterol were observed as significantly decreased enzyme activities of alanine aminotransaminase (ALT), aspartate aminotransaminase (AST) and alkaline phosphatase (ALP) in the larval midgut. Suppression of enzyme activity was obtained in the order ALT>AST>ALP. Impaired activity of gut enzymes possibly lowered the energy reserves and affected nutrient transport through the gut epithelium, affecting the growth and development of H. armigera. Our study points to a promising use of ?-sitosterol against H. armigera, although further examination and field studies are needed to ascertain its possible use in control programs.

Docking-Based Virtual Screening Ascertaining β-Sitosterol-Induced Alterations in the Helicoverpa armigera Hübner Gut Enzymes

“…On the other hand, enzymes gain additional dynamics and activity at the cost of stabilizing interactions. Present results are supported by our previous results that dietary β-sitosterol caused highest suppression of ALT enzyme activity (> 50%) in H. armigera larvae in comparison to the AST and ALP (Mishra et al, 2020). This proposes that decreased activity of ALT was accompanied by a concomitant increased stability caused by interactions and vice-versa in remaining two enzymes.…”

“…Our earlier investigations showed the potential of β-sitosterol in disrupting physiological process and adequate growth and development which was proposed to be due to the accumulated effects of β-sitosterol and diminished midgut enzymatic activities (Mishra et al, 2020). As an extension of these studies, present investigations attempted to discover the exact binding sites of the target midgut enzymes with β-sitosterol through docking based virtual screening.…”

“…The earlier work has shown the inhibitory effect of β-sitosterol on three midgut enzymes -alanine aminotransaminase (ALT), aspartate aminotransaminase (AST) and alkaline phosphatase (ALP) of H. armigera in the order of ALT > AST > ALP with percent inhibition of 59.17, 42.51 and 29.31, respectively (Mishra et al, 2020). Thus, these enzymes were selected for docking-based studies to ascertain the effects of β-sitosterol in H. armigera.…”

“…Our investigations on the effects of β-sitosterol on the physiological fitness and midgut enzymes of H. armigera revealed developmental abnormalities in H. armigera induced by the dietary β-sitosterol, an active phytocomponent identified from T. neriifolia stem extract (0.1-10 ppm) (Mishra et al, 2020). The larval and pupal weight gain reduced, the adult emergence dropped to 82.05% to 57.89% in comparison to 95.02% emergence in controls and the midgut biochemistry also altered significantly diminishing activity of three midgut enzymes; alanine aminotransaminase (ALT), aspartate aminotransaminase (AST) and alkaline phosphatase (ALP) (Mishra et al, 2020).…”

Chemical composition, toxicity and physiological effects of thyme oil and its two components on mulberry pyralid moth

“…The results of this study showed that the decrease in enzyme activity was dosedependent. Higher concentrations of β-cytosterol in the diet further suppress enzymatic activity (Mishra et al 2020). Also, similar results in studies on the insecticidal properties of essential oils of Wedelia trilobata (L.) (Asteraceae) and Melissa o cinalis (L.) (Lamiaceae) showed that the activity of alanine and aspartate aminotransferases were signi cantly decreased compared to the control (Khater and El-Sha ey 2015).…”