Deltamethrin-Mediated Effects on Locomotion, Respiration, Feeding, and Histological Changes in the Midgut of Spodoptera frugiperda Caterpillars
2021
Vinha, Germano Lopes | Plata-Rueda, Angelica | Soares, Marcus Alvarenga | Zanuncio, José Cola | Serrão, José Eduardo | Martínez, Luis Carlos
Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) is the main pest of maize crops, and effective methods for pest management are needed. The insecticidal efficacy of deltamethrin was evaluated against S. frugiperda for toxicity, survival, locomotion, anti-feeding, and histological changes in the midgut. Concentration–mortality bioassays confirmed that deltamethrin (LC₅₀ = 3.58 mg mL⁻¹) is toxic to S. frugiperda caterpillars. The survival rate was 99.7% in caterpillars not exposed to deltamethrin, decreasing to 50.3% in caterpillars exposed to LC₅₀, and 0.1% in caterpillars treated with LC₉₀. Spodoptera frugiperda demonstrated reduced mobility on deltamethrin-treated surfaces. Deltamethrin promoted a low respiration rate of S. frugiperda for up to 3 h after insecticide exposure, displaying immobilization and inhibiting food consumption. Deltamethrin induces histological alterations (e.g., disorganization of the striated border, cytoplasm vacuolization, and cell fragmentation) in the midgut, damaging the digestive cells and peritrophic matrix, affecting digestion and nutrient absorption.
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