Silicon Supplementation Reinforces Maize Defence to Defeat the Oriental Armyworm

Maize is a critical component of global food security; however, pests like the oriental armyworm (Mythimna separata Walker) cause significant yield losses to this crop. Conventional control approaches for managing this insect rely on pesticide applications, which pose environmental risks and can lead to pest resistance. Thus, the necessity for alternative management strategies is emphasised. Silicon (Si) is proposed as a pesticide substitute due to its ability to mitigate a plethora of biotic and abiotic stresses in plants. To evaluate the effectiveness of Si in controlling the armyworm, maize plants were treated with three Si concentrations (T1: 500 mg/L, T2: 750 mg/L, T3: 1000 mg/L) and then infested with armyworm larvae. The performance of the insect pest was assessed by evaluating its larval feeding and oviposition preference, mandibular morphology, survival rates and weight gain. Results showed a mean larval survival rate of 63% in T3 plants compared to 96% in control. The weight of larvae fed on control leaves was twice that of those fed on Si-treated leaves. Likewise, the incisor length of larvae fed on Si-treated leaves was significantly shorter (177 μm) than those fed on control leaves (447 μm). Moreover, Si-treated leaves were less favourable for egg laying, with only 20% of eggs laid on them. These findings indicate that Si supplementation enhances maize resistance to the infestation of the oriental armyworm. This Si-mediated resistance of maize plants against the oriental armyworm underscores the potential of Si supplementation as a sustainable alternative to chemical pesticides in integrated pest management strategies.