Development and insecticidal evaluation of a microencapsulated plant-derived bioinsecticide from Albizia kalkora against Hyphantria cunea

Abstract

The Hyphantria cunea (Lepidoptera: Erebidae), a significant invasive pest, has inflicted substantial economic damage on global agriculture and forestry. Plant-derived pesticides formulated as microcapsules present promising prospects for pest management. This study identified key insecticidal compounds from Albizia kalkora (Leguminosae: Rosales), a low-preference host for H. cunea, and developed them into microencapsulated insecticides. Esculetin, pinpointed as the principal anti-insect compound in A. kalkora, exhibited strongest toxicity against H. cunea, manifesting as reduced larval body weight, elevated mortality rates, and altered expression of genes regulating growth. The compound also depleted larval nutrient reserves and suppressed critical gene expression in the tricarboxylic acid cycle and glycolytic pathways. Despite the activation of detoxification and antioxidant systems in esculetin-treated larvae, oxidative damage remained unresolved. Microcapsules containing esculetin, fabricated via the single coagulation method, demonstrated superior slow-release behavior, thermal stability, and resistance to photodegradation. Laboratory and field trials confirmed that esculetin microcapsules exerted comparable or greater toxic effects than unformulated esculetin on larval growth, survival, oxidative stress, nutrient content, and energy metabolism. Additionally, esculetin microcapsules were categorized as low-toxicity pesticides, with negligible adverse effects on Danio rerio (Cyprinidae: Cypriniformes) and Arma chinensis (Hemiptera: Pentatomidae). Thus, microencapsulated insecticides utilizing esculetin as the active component provide an effective, safe, and environmentally sustainable strategy for managing H. cunea infestations.