Insecticidal property of Ocimum essential oil embedded polylactic acid packaging films for control of Sitophilus oryzae and Callosobruchus chinensis

Naturally derived essential oils (EOs) from Ocimum basilicum (OB) and Ocimum gratissimum (OG) were incorporated
in polylactic acid (PLA) matrix with concentration of 2.5 % and 5 % respectively by solvent casting
method, with an aim to develop insecticidal polymer pouches (insect proof polymer pouches). The major
components following GC–MS analysis revealed the presence of EOs as estragole (69.998 %) in OB and thymol
(29.843 %) in OG. The developed films with EOs showed remarkable insecticidal activity with 100 % and 80 %
mortality rate for OB and OG respectively at 2.5 % concentration against rice weevil (Sitophilus oryzae). While,
both OB and OG EOs observed 100 % mortality against pulse beetle (Callosobruchus chinensis) after 96 h exposure
in presence of grain conditions and the insecticidal efficacy was equivalent to the commercial hermetic bags
(CSB). The physical property of film showed increase in the film thickness in EO-PLA films whereas the mechanical
properties of EO-PLA films matrix have increased the polymer flexibility with decreasing tensile
strength (TS) and Youngs modulus (EM) as TS OB 5 %, OG 5 % - 15.64 MPa, 17.66 MPa respectively. While,
water vapour transmission rate (WVTR) was reduced to 0.015 g/m2.hr, optical characteristics showed slight
significant change in colour and FTIR spectra exhibited a change in -OH stretching compared to blank PLA
matrix. The surface morphology of the blank and EO embedded PLA films visualized by SEM depicted a complete
homogenization of essential oils in the PLA matrix.