Enhancement of groundnut ( Arachis hypogaea L.) leaves with silica supplementation influences nutritional indices and development of Spodoptera litura Fab. and Helicoverpa armigera Hub. (Lepidoptera: Noctuidae)

BACKGROUND: Groundnut (Arachis hypogaea L.) is a major oilseed crop globally, but its productivity is severely affected by polyphagous pests such as Spodoptera litura Fab. and Helicoverpa armigera Hub. (Lepidoptera: Noctuidae). These lepidopteran pests cause significant damage to foliage, resulting in yield losses. Silicon (Si), an abundant element in the Earth's crust, is increasingly recognized for its role in enhancing plant resistance to biotic stress. This study aimed to evaluate the impact of calcium silicate supplementation on the developmental biology and nutritional physiology of S. litura and H. armigera larvae feeding on groundnut leaves. RESULTS: Groundnut plants were treated with calcium silicate via foliar spray (2.0%, 3.5%, 5.0%), soil drenching (10%, 15%, 20%) and combined applications. Larval and pupal durations were significantly prolonged under combined treatments (e.g. S. litura larval period: 17.81 days versus 16.13 days in control; pupal period: 11.62 versus 10.36 days). Nutritional indices declined markedly: efficiency of conversion of ingested food (ECI) in H. armigera decreased from 18.65% (control) to 15.31% (treated), and efficiency of conversion of digested food (ECD) in S. litura dropped from 18.14% to 14.02%. Relative consumption and growth rates also were reduced, indicating impaired feeding and growth performance. CONCLUSION: Calcium silicate application, particularly through combined foliar and soil treatments, negatively influenced larval development and food utilization in S. litura and H. armigera. These findings highlight silicon's potential as an ecofriendly component of integrated pest management strategies in groundnut cultivation, offering a sustainable alternative to synthetic insecticides. © 2026 Society of Chemical Industry.