Portulaca oleracea

D., AmanY, Elham, Abd-Elnabi ·, El-saWY, Abdel Fattah, Mohamed, El-saWY ·, BadaWY, E. I. & Keywords, BadaWY Abstract, 2025, Plant Oil Nano-Emulsions as a Potential Solution for Pest Control in Sustainable Agriculture, Neotropical Entomology (35) 54 (1), pp. 35-35 : 4-8

Characterization of P. oleracea , R. sativus , and R. officinalis Oil Nano-Emulsions

The prepared nano-emulsion formulations which contain 10% (ml/ml) of P. oleracea , R. sativus , and R. officinalis were characterized in terms of droplet size, polydispersity index (PDI), zeta potential, morphological structure, and thermodynamic characterization ( Table 4 ). The droplet size distribution and morphological structure of purslane, rosemary, and radish oil nano-emulsions are shown in Figs. 1 and 2 . In our study, the average size of the nano-emulsions was found to be less than 200 nm; the particle sizes for purslane radish and rosemary are 26.67 nm, 134.9 nm, and 97.36 nm. The obtained values in this study of PDI are less than 0.3; the PDI of purslane oil is 0.186, 0.190 for radish oil, and 0.202 for rosemary. Zeta potential which characterizes the surface charge of the nano-emulsion particles is an important factor for nano-emulsion stability. Zeta potentials of purslane, radish, and rosemary nano-emulsions are − 0.69 mV, − 29.9, mV, and − 18.00 mV, respectively ( Table 4 ). The TEM images ( Fig. 2 ) investigated the spherical appearance of synthesized o/w nano-emulsion and showed droplet mean size in the range of 200 nm.

The stability of nano-emulsion formulations is an important character that indicates the shelf-life of the formulations. The prepared nano-emulsions passed the thermodynamic tests (freeze–thaw cycle, centrifugation, and heating–cooling cycle). The nano-emulsions showed stable formulation without any sign of instability such as phase separation sedimentation or creaming. The nano-formulations were physically stable up to 3 months from the preparation. The viscosity of prepared nano-emulsions is 24.7 mPas for purslane, 26 mPas for radish, and 6.5 mPas for rosemary ( Table 4 ).

Toxicity Effects of Oils and Their Nano-Emulsions

The pesticidal efficacy of purslane, radish, and rosemary oil–based nano-emulsions was compared to that of the pure oil against A. gossypii , S. littoralis , and T. urticae in this study. It is clear from data presented in Tables 5 and 6 that all formulation forms caused different mortality levels against the selected pests after 24 h from exposure.

The results showed that the tested oils have positive toxic effects, and purslane oil exhibited the highest insecticidal activity against A. gossypii with LC 50 = 85.02 mg /L followed by radish and rosemary with LC 50 = 555.42 and 869.64 mg /L, respectively. However, rosemary and purslane oil nano-emulsion record the same greatest impact on A. gossypii with LC 50 = 72.45 and 72.74 mg /L, respectively, followed in descending order with radish oil nano-emulsion with LC 50 = 453.91 mg /L. Furthermore, the acaricidal activity of the tested oils and their nano-emulsion against T. urticae is presented in Table 5 . According to the LC 50 values, purslane oil is most active than radish and rosemary oil, with LC 50 values = (291.05, 235.86), (359.95, 263.54) and (337.46, 240.98) mg/L, for bulk and nano-emulsion oil, respectively. These results indicate that the tested oil nano-emulsions have efficiency and may be used as insecticide and acaricide agents.

PDI poly disparity index

√—passed the test

The insecticidal effects of the tested oils and their nano-emulsions using the residual bioassay method on 4th instar larvae of S. littoralis are shown as LD 50 values in Table 6 . All oils caused mortality against S. littoralis compared with the control, the result indicating that among the tested oils, purslane oil (nano and bulk) had a high toxic effect against S. littoralis after 24 h (LD 50 = 55.35 ppm and 96.1 ppm), followed by rosemary (nano and bulk) with LD 50 = 120 ppm and 113 ppm, respectively. Conversely, radish oil (nano and bulk) was less effective on S. littoralis with LD 50 = 123.06 and 140.89 ppm (nano and bulk).

Figures

Fig. 1 Transmission electron microscope (TEM) of the prepared oil nano-emulsions for Portulaca oleracea (A), Raphanus sativus (B), and Rosmarinus officinalis (C)

Fig. 2 Dynamic light scattering (DLS) of the prepared oil nano-emulsions for Portulaca oleracea (A), Raphanus sativus (B), and Rosmarinus officinalis (C)