Nanobiopesticides: development and inseticidal activity of nanoemulsions containing lemongrass or eucalyptus oils.

The bioinsecticides, like essential oils, are a promising alternative in pest control. However, these oils have some limitations, such as instability and low solubility. These limitations can be circumvented through nanotechnology, with the nanoemulsification of these compounds. Therefore, the objective of this study was to prepare, characterize and explore the insecticidal activity against adult flies of nanoemulsions containing essential oil of lemongrass or eucalyptus. The nanoemulsions were prepared by the high-energy method and presented droplet size smaller than 125 nm, with polydispersity index of 0.2, pH acid and spherical morphology. The insecticidal activity was evaluated by the Topical Application Method and Exposure Impregnated Paper Exposure, where it was possible to demonstrate a potential insecticidal effect of lemongrass oil in the concentrations of 10, 30 and 50 µL/mL against Musca domestica and Lucilia cuprina and the potentiation of this effect when nanoemulsified this oil against L. cuprina.

Adulticidal Activity of Melaleuca alternifolia (Myrtales: Myrtaceae) Essential Oil With High 1,8-Cineole Content Against Stable Flies (Diptera: Muscidae).

The stable fly, Stomoxys calcitrans (Linnaeus 1758), is a hematophagous fly responsible for causing loss of performance in horses, causing losses in cattle productivity, and impacting the animals' health through the spread of pathogenic microorganisms. The objective of this work was to investigate the insecticidal activity of essential oil obtained from Melaleuca alternifolia (Cheel), presenting high 1,8-cineole content, against S. calcitrans adults. Insecticidal activity was determined using surface application methods and exposure to oil impregnated paper. It was observed that treatments at 25 and 50 µg/cm2 (P < 0.05) present fumigant activity through exposure to the impregnated paper, and in the first 15 min of exposure, the mortality rates obtained for these treatments were, respectively (96.6 ± 3.3% and 100%), equivalent to the positive control. Using the superficial application method, the only treatment concentration presenting adulticidal action was 5% (w/v) (P < 0.05). Respective toxicities LC50 (%, w/v) and LC80 for the impregnated paper method were 1.06 ± 0.02 and 1.47 ± 0.17; for the superficial application method, they were 3.82 ± 0.65 and 5.53 ± 0.74. As demonstrated, M. alternifolia essential oil presents adulticidal potential against S. calcitrans.