Acaricidal Efficacy of Biosynthesized Zinc Oxide Nanoparticles Against Hyalomma dromedarii (Acari: Ixodidae) and Their Toxic Effects on Swiss Albino Mice.

PURPOSE: The current study aimed to investigate the efficacy of zinc oxide nanoparticles (ZnO NPs) synthesized by Melia azedarach aqueous extract to control Hyalomma dromedarii tick, and to evaluate their toxic effects on Swiss albino mice. METHODS: ZnO NPs were synthesized using M. azedarach aqueous extract. UV-visible spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive spectroscopy were used to characterize the synthesized NPs. Egg, nymph, larva, and adult immersion tests were used for bioassay of tick stages with the synthesized ZnO NP. A toxicity study was performed on Swiss albino mice after treatment with 1/10 of the oral LD50 of ZnO NPs (8437 mg/kg) for 5 successive days by oral gavage. RESULTS: The LC50 of ZnO NPs on the eggs, larvae, and nymphs was 11.6, 8.03, and 3.9 mg/ml, respectively. The reproductive performance of females treated with ZnO NPs was lower than that of untreated females. The hematological results showed an insignificant increase in the level of white blood cells with normal red blood cells, hemoglobin, in addition to normal platelet count. The biochemical analysis showed an insignificant increased level (P > 0.05) of alkaline phosphatase and alanine aminotransferase. The liver and kidney suffered few histopathological changes after oral administration of ZnO NPs. CONCLUSION: These results suggest that ZnO NPs have good acaricidal activity against eggs, larvae, and engorged nymphs of H. dromedarii. ZnO NPs minimized the number of eggs laid by engorged females and the hatchability of their eggs. ZnO NPs did not affect unfed adults. The toxicity results of the mice revealed insignificant changes in the hemogram, biochemistry, with liver and kidney suffering few histopathological changes. Future studies are needed to assess application routes (topical vs oral). Based on these findings, ZnO NPs may be incorporated in the control of camel tick H. dromedarii.

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.

In vitro acaricidal effect of Melia azedarach and Artemisia herba-alba extracts on Hyalomma dromedarii (Acari: Ixodidae): embryonated eggs and engorged nymphs.

The present study aimed to evaluate the in vitro efficacy of four medicinal plant extracts: petroleum ether and ethyl alcohol extracts of the ripen fruits of Melia azedarach and whole aerial parts of Artemisia herba-alba against the two inactive stages of the camel tick Hyalomma dromedarii, embryonated eggs and engorged nymphs in comparison to reference acaricide Butox®5.0 (Deltamethrin). Egg and nymphal immersion tests at four concentrations with three replicates were used. The deformity in larvae hatched from treated eggs and adults moulted from treated nymphs were observed and photographed by light microscope (LM) and scanning electron microscope (SEM). The results showed that M. azedarach and A. herba-alba extracts revealed higher significant toxic effects on embryonated eggs and engorged nymphs comparing with the reference acaricide (Butox®5.0) and control. In egg emmersion test, the LC50 of petroleum ether extracts of M. azedarach and A. herba-alba was 3.14 and 3.91%, respectively and LC50 of the respective ethyl alcohol extracts was 1.77 and 2.45%. In nymphal immersion test, LC50 of petroleum ether extracts of M. azedarach and A. herba-alba was 0.26 and 1%, respectively, and LC50 of the respective ethyl alcohol extracts was 4.17 and 8.7%. Abnormalities were observed by LM and SEM in the larvae hatched from the treated eggs as incomplete development of legs and mouth parts as well as shrinkage mainly in legs and mouthparts of adults emerged from treated nymphs. In conclusion, all extracts and petroleum ether extracts of the two plants have great potential to be developed as a novel acaricidal for controlling eggs and nymphs of H. dromedarii, respectively.