Development and evaluation of castor oil nanoemulsion on the cotton leaf worm Spodoptera littoralis (Boisd.) and its adverse effects on the reproductive system of albino rats

Different formulations, such as nanoemulsions, have been widely used in recent years for target delivery and enhanced biological functions of pesticide combinations. Castor oil was formulated by using a new generation of formulations as nanoemulsions; bio-based oil-in-water nanoemulsion was conducted by a low-energy method. The nanoemulsion characterization and evaluation including pH, viscosity, zeta potential value, and the particle size distribution of the nanoemulsion were measured. The formulation was a good nanoemulsion, and the formula exhibited acidic pH value (5.90), viscosity 90.40 cPs, zeta potential - 20 mV, and size distribution 174.6 nm, and polydispersity index (PDI) of the nanoemulsion was found to be 0.393. Castor oil nanoemulsion successfully passed all the thermodynamic stability tests, with no phase separation, cracking, or creaming. It is suggested that castor oil can be used as a good oil phase in nanoemulsion formulation. The bioassay technique was performed using thin film to estimate LC50 and LC90 values against the 4th instar larvae of the cotton leaf worm Spodoptera littoralis (Boisd.) under laboratory conditions. Castor oil nanoemulsion was the most effective followed by castor oil, where the LC5o and LC9o values were 9.05 and 40.59 ppm/cm(2), respectively, for castor free oil. To our knowledge, no studies have been conducted on the adverse effects of castor oil with a new nanoemulsion formulation on hormonal and histological changes in the reproductive system of albino rats in Egypt which stimulated our interest to investigate this in nano-sized in Egypt. However, the reproductive system toxicity was monitored by quantitative analysis of the serum luteinizing hormone (LH), follicle-stimulating hormone (FSH), progesterone (Prog), testosterone (Testo), and prolactin (PRL). The reproductive organs were collected for histopathology study. No histopathological changes in the ovaries or testes were observed at any dose. In males, no treatment-related changes in the levels of Testo, LH, and FSH were observed at any dose. In females, no changes in the levels of FSH, LH, prolactin, and progesterone were observed at any dose. These results suggest that castor oil nanoemulsion has no effect on gonadotropic or hormone levels in either sex at doses 100-200 mg/kg/14 days.