Inhibition of carbohydrate-digesting enzymes in Spodoptera frugiperda (Lepidoptera: Noctuidae): implications for pest control

The fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a globally significant agricultural pest capable of devastating cereal crops and other economically important plants. The present study investigates the in vitro inhibitory effects of copper(II) sulfate (CuSO₄), ethylenediaminetetraacetic acid (EDTA), and sodium chloride (NaCl) on key carbohydrate-digesting enzymes in the fourth instar of S. frugiperda , with a particular emphasis on invertase. Enzyme activity profiling revealed that invertase dominates carbohydrate metabolism in adults, while trehalase and amylase are more active in larvae. CuSO₄ exhibited the strongest inhibition, completely suppressing invertase, trehalase, and amylase activity at 0.5 M ( P < 0.01), with significant dose-dependent suppression evident even at 0.01 M. EDTA exerted significant but less potent inhibition, reducing enzyme activities by approximately 24–38% at 0.5 M ( P < 0.01). NaCl showed negligible inhibitory effects across all tested concentrations (0.1–2.0 M; P > 0.05 at ≤ 0.1 M for amylase). Notably, CuSO₄ inhibition was rapid, requiring less than two minutes to achieve near-complete suppression at 25 °C, and was significantly influenced by temperature. The strong inhibitory effect of CuSO₄ suggests that it disrupts key metabolic pathways in S. frugiperda , likely through protein denaturation and metal ion interference. These findings highlight the potential of CuSO₄ as a biochemical disruptor that could be further explored as a novel pest control strategy. Future research should focus on in vivo assessments of CuSO₄ toxicity, its interactions with insect physiological processes, and its potential integration into sustainable pest management programs.