Essential oils of Cinnamomum loureirii and Evolvulus alsinoides protect guava fruits from spoilage bacteria, fungi and insect (Pseudococcus longispinus)

The present study aimed to evaluate the crop protection properties of essential oils (EOs) extracted from Cinnamomum loureirii and Evolvulus alsinoides against food spoilage fungi and insects. Hydrodistillation method and Gas Chromatography-Mass Spectrophotometry analysis authenticated the presence of twenty three compounds from C. loureirii including, cinnamaldehyde (74.31 %), linalool (1.72 %), camphor (1.3 %), borneol (1.25 %) and bisabolol (1.31 %) and twenty compounds from E. alsinoides with cis-α-necrodol (13.06 %) as the major component. Results confirmed that two EOs revealed potent activity against various bacterial pathogens and fruit spoilage fungal strains. The Minimum Inhibitory Concentration values ranged between 2.1 ± 0.3 and 4.3 ± 0.2 μg/mL and Minimum Bactericidal Concentration values varied between 6.5 ± 0.25 and 13.4 ± 9.2 μg/mL. The EO was highly active against Klebsiella pneumoniae and Pseudomonas aeruginosa. Interestingly, the EO from C. loureirii induced larval mortality (100 ± 0% at 80 μg/mL) than EO from E. alsinoides (90 ± 2.5 % at 80 μg/mL), whereas the mixture of both EO revealed 100 % mortality at 80 μg/mL concentrations. Interestingly, both EOs showed excellent activities against A. aegypti. In addition, the EO vapour significantly suppressed the pest, mealy bug (Pseudococcus longispinus) affected fruit and leaves of Guava, Psidium guajava. In vivo analysis revealed the protection property against rot forming fungal pathogens. The increasing concentration of EOs significantly protected from rot formation in Guava fruit. The antioxidant potentials of EO was an additional value added advantage. Overall, it is concluded that EOs could be effectively used in the control of postharvest bacterial, fungal pathogens and storage pests.