Biopesticidal silo bag prepared by co-extrusion process

Abstract

Silo bag technology is used for storing grains in a hermetic plastic structure. The major limitation of this structure is resistance to improper handling and external aggression, thus promoting pest incidence due to alterations in its internal atmosphere. In this study, we developed a biopesticidal silo bag consisting of a co-extruded three-layer film made of polyethylene and essential oil of Mentha piperita (7% w/w) in the inner layer. A film with the same structure but without essential oil was produced to be used as a control. The presence of the biopesticide in the silo bag was confirmed by FTIR-spectroscopy. Thus, mechanical, optical and chemical properties were evaluated. Diffusion coefficient of biopesticide from silo bag at 15, 25 and 35 °C was estimated as 6.4 ± 0.1 × 10-11, 1.45 ± 0.17 × 10-10 and 1.30 ± 0.2 × 10-10 cm2/s, respectively. Finally, the biopesticide silo bag was tested against Rhyzopertha dominica, primary pest of stored grain, showing 100 % of mortality during the time assayed (7 days). Hence, the incorporation of biopesticide by co-extrusion technology (low-cost and efficient machinery) into the inner layer of a silo bag could help to replace synthetic pesticides and avoid manipulation of these in the field, preventing biotic infestation.