Deltamethrin-Mediated Effects on Locomotion, Respiration, Feeding, and Histological Changes in the Midgut of Spodoptera frugiperda Caterpillars.

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.

Life Table Parameters of the Zoophytophagous Predator Brontocoris tabidus (Heteroptera: Pentatomidae) on Introduced and Native Plants.

Brontocoris tabidus Signoret (Heteroptera: Pentatomidae) is a zoophytophagous predator of lepidopteran defoliators of eucalyptus in Brazil. This predator complements its diet with plants, which is fundamental for its population maintenance. The objective was to evaluate the B. tabidus development, reproduction, and life table parameters in the field on Eucalyptus cloeziana F. Muell. (T1), Psidium guajava Linn (Myrtales: Myrtaceae) (T2), or without plants (T3). The parameters estimated were: net reproductive rate (Ro); generation duration (DG); time for the population to double in size (TD); intrinsic population growth rate (rm), survival rate (lX), specific fertility (mx), life expectancy (ex), and mortality risk (qx). Ro, DG, TD, and rm were higher in the T1 and T2 than in T3. Plant presence favored the lx, mx, and qx. Ex values were 36.1 and 56.9 in the T3 and T1, respectively. The B. tabidus fertility, longevity, and life table parameters improvement on E. cloeziana and P. guajava plants are due to the water and nutrients obtained from them. B. tabidus can be reared with Tenebrio molitor Linnaeus (Coleoptara: Tenebrionidae) pupae on E. cloeziana or P. guajava plants in the field.