Repellency effect of Pilocarpus spicatus A. St.-Hil essential oil and nanoemulsion against Rhipicephalus microplus larvae

Acaricidal activity of Artemisia herba-alba and Melia azedarach oil nanoemulsion against Hyalomma dromedarii and their toxicity on Swiss albino mice

Biopesticides such as essential oils (EOs) are considered an improvement for integrated pest control as they appear to be less toxic to the environment than chemical acaricides. The current study aimed to evaluate the acaricidal activity of Artemisia herba-alba and Melia azedarach oil loaded nano-emulsion as alternatives for chemical acaricides against the camel tick Hyalomma dromedarii, besides evaluating their toxic effect on Swiss albino mice. Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) were used for the characterization of loaded nano-emulsions.The immersion test was used for the bioassay of both loaded nanoemulsions on tick stages (egg, nymph, larva, and adult). Mortality percentages and LC₅₀ values of each tick stage were calculated. Reproductive performance for the survived engorged females after treatment was monitored. The toxicity of both loaded nano-emulsions was evaluated on Swiss albino mice by an oral dose of 1500 mg/kg/day for five successive days. The hematological, biochemical, and histopathological changes were evaluated. TEM characterization revealed spherical droplets for A. herba-alba and M. azedarach oil loaded nano-emulsion with droplet size ranging from 62 to 69 nm and 52-91 nm, respectively. FTIR revealed the absence of extra peaks in the loaded nano-emulsions that confirmed no chemical changes existed by ultrasonication. The LC₅₀ values of A. herba-alba and M. azedarach oil loaded nano-emulsion on embryonated eggs, larvae, engorged nymphs, and unfed adults were 0.3 and 1.1%, 0.7 and 1.7%, 0.3 and 0.4%, 4.4 and 22.2%, respectively. The egg productive index (EPI), egg number, and hatchability percentage were lower in the treated females compared with Butox 5% (deltamethrin) and control. The hematological picture and biochemical analysis revealed insignificant changes in the treatment group compared with the negative control group. The liver of the A. herba-alba and M. azedarach oil loaded nano-emulsion treated group exhibited vacuolar degeneration and infiltration of lymphocytic cells. The kidney of mice treated with A. herba-alba and M. azedarach oil loaded nano-emulsion showed hemolysis and slight degeneration of epithelial cells of tubules. It is concluded that A. herba-alba and M. azedarach oil loaded nano-emulsion have good acaricidal activity against camel tick H. dromedarii.