Efficacy evaluation of Eucalyptus globulus essential oil-based nanoemulsion- a green insecticide against Callosobruchus maculatus

Among the storage insects, Callosobruchus maculatus is reported to cause significant damage to legumes, resulting in 5–10% postharvest loss. Conventionally used synthetic chemical pesticides raised significant health concerns among consumers. The present study aimed to develop a eucalyptus essential oil-based nanoemulsion (EO-NE) and test its efficacy against C. maculatus. The developed EO-NE with a surfactant: oil ratio of 5 was kinetically stable, with no phase separation, creaming, or crystallization after 60 days. EO-NE droplets were spherical, with average droplet size and polydispersity index of 17.16 nm and 0.313, respectively. Increased adhesiveness and wettability of EO-NE are correlated with optimal viscosity (53.51cPs) and reduced contact angle (45°). FTIR analysis assured efficient oil trapping inside nanoemulsions without significant changes in functional groups. The effective repellence of C. maculatus was validated by negative excess proportion index values. According to the data, the EO-NE concentration and exposure period are directly proportional to insect mortality. These findings imply that EO-NE may be employed as a green insecticide to manage C. maculatus infestations in grain-storage facilities.