Work

Toxicity of Nanoemulsified Eugenia uniflora (Myrtaceae) Essential Oil to Spodoptera frugiperda (Lepidoptera: Noctuidae) and Selectivity to Trichogramma pretiosum (Hymenoptera: Trichogrammatidae)

Year: 2026

Type: article

Abstract: Spodoptera frugiperda (fall armyworm) is a polyphagous pest with widespread resistance to synthetic insecticides, while essential oils (EOs) and biological control agents, such as the parasitoid Trichogramma pretiosum, represent promising strategies in integrated pest management (IPM) programs. This study evaluated the toxicity of Eugenia uniflora EO, popularly known as pitanga EO, and nanoemulsion (NEO) to S. frugiperda and the selectivity of the NEO to T. pretiosum. The EO of E. uniflora was characterized by GC-MS/DIC and then diluted in water and Tween 80® for bioassays to estimate the LC50 against S. frugiperda in Potter’s tower. The NEOs were produced by high-shear dispersion using an Ultra-Turrax and characterized for thermal stability, particle size, polydispersity index (PDI), zeta potential (ζ), temporal stability, and morphology. The NEO was diluted to the LC50 (36.05 mg/mL) in 1% Tween 80® solution and tested for toxicity to S. frugiperda and to the parasitoid. The majority compounds in the EO from E. uniflora were curzerene (34.07%), selina-1,3,7(11)-trien-8-one (10.51%), germacrene B (9.51%) and germacrene D (5.03%). The NEO stored at 25 °C remains stable for up to 30 days after preparation. In addition, the NEO showed a particle size of 283.2 nm, a PDI of 0.289, and a zeta potential (ζ) of −23.2 mV. The E. uniflora EO and NEO at a concentration of 36.05 mg/mL were toxic to S. frugiperda (36% probability of survival). Furthermore, NEO was selective for T. pretiosum in its immature stages. The NEO proved to be stable, effective, and selective, indicating potential for IPM. However, validation under semi-field and field conditions is still necessary.

Source: Plants

DOI: 10.3390/plants15020248