Slow-release fenobucarb nanofibers: A case study on field efficacy against brown planthopper in rice cultivation in Vietnam

Polylactic acid nanofibers encapsulating the insecticide fenobucarb were fabricated by coaxial electrospinning and evaluated for structure, release, and field efficacy in rice.The nanofibers showed an average diameter of 582.12 ± 108.49nm with 47.175% fenobucarb loaded.In vitro, fenobucarb release reached 22.78% at day 5 and 43.19% at day 15, fitting the Korsmeyer Peppas model (n = 0.6014), indicating both profenofos diffusion and the swelling of the polylactic acid shell.Three formulations suspension concentrate, wettable powder, and granule were prepared from the nanofibers scaffolds and applied at 250 g a.i.ha⁻¹ in Bac Giang province, Vietnam.No phytotoxicity was detected.Both suspension concentrate and wettable powder reduced brown planthopper densities from 27 insects hill⁻¹ to 4.3-4.5 insects hill⁻¹ by 15 days after treatment, with efficacy of 86.1 ÷ 86.8%, outperforming the commercial reference Bassa 50 EC (64.9%).Granule exhibited slower onset but extended activity.Compared with conventional formulations, polylactic acid encapsulation enhanced persistence and bioefficacy, suggesting a practical strategy to lower insecticide input and environmental exposure in rice ecosystems.