Development of an environmentally friendly nanoemulsion based on Ginkgo biloba exocarp extracts to control Plutella xylostella

Abstract

The chemical compositions of Ginkgo biloba exocarp extracts (GBEE) and leaf extracts are similar, however, studies describing the development of GBEE biopesticides are few. In this study, the authors investigated the preparation of GBEE nanoemulsionand and characterized by transmittance, physical stability, droplet size and size distribution for the first time. Insecticidal activity and lipophilicity screening of four different solvents indicated ethyl acetate was satisfactory. Based on dispersibility, centrifugation, heating-cooling cycle, cloud point and long-term stability experiments, two formulations (ethyl acetate/Tween 40-Span 60 (9:1)/water and ethyl acetate/Tween 60-Span 60 (9:1)/water) were optimum to formulate nanoemulsions. However, the smallest droplet size and size distribution (10.93 ± 0.16 nm, PDI = 0.15 ± 0.01) was obtained using the Tween 60/Span 60 combination. The insecticidal activity of GBEE nanoemulsion was evaluated against the third instar larvae of Plutella xylostella. Lethal concentration (LC50) values of the optimized nanoemulsion were 127.38 mg/L at 12 h and 72.80 mg/L at 24 h, respectively. This indicated that GBEE nanoemulsion had higher insecticidal activity than the GBEE. The results proposed that the GBEE nanoemulsion is a potential and effective natural alternative for the management of P. xylostella.