Acaricidal activity of tea tree and lemon oil nanoemulsions against Rhipicephalus annulatus

Tick infestation is a serious problem in many countries since it has an impact on the health of animals used for food production and pets, and frequently affects humans. Therefore, the present study aimed to investigate the acaricidal effects of nanoemulsions of essential oils o

Toxicity and Repellency Efficacy of Benzyl Alcohol and Benzyl Benzoate as Eco-Friendly Choices to Control the Red Flour Beetle <i>Tribolium castaneum</i> (Herbst. 1797)

Tribolium castaneum is a damaging pest of stored grains, causing significant losses and secreting lethal quinones, which render the grains unfit for human consumption. Chemical insecticides are the most commonly used approach for control; however, they create insecticide resistance and affect the health of humans, animals, and the environment. As a result, it is critical to find an environmentally friendly pest-management strategy. In this study, two naturally occurring chemicals, benzyl alcohol (BA) and benzoyl benzoate (BB), were investigated for insecticidal activity against T. castaneum using different assays (impregnated-paper, contact toxicity, fumigant, and repellency assays). The results showed that BA had a significant insecticidal effect, with the LC50 achieved at a lower concentration in the direct-contact toxicity test (1.77%) than in the impregnated-paper assay (2.63%). BB showed significant effects in the direct-contact toxicity test, with an LC50 of 3.114%, and a lower toxicity in the impregnated-paper assay, with an LC50 of 11.75%. Furthermore, BA exhibited significant fumigant toxicity against T. castaneum, with an LC50 of 6.72 µL/L, whereas BB exhibited modest fumigant toxicity, with an LC50 of 464 µL/L. Additionally, at different concentrations (0.18, 0.09, 0.045, and 0.0225 µL/cm2), BA and BB both showed a notable and potent repelling effect. BA and BB significantly inhibited acetylcholinesterase, reduced glutathione (GSH), and increased malondialdehyde (MDA) in treated T. castaneum. This is the first report of BA insecticidal activity against the red flour beetle. Also, the outcomes of various assays demonstrated that the application of BA induces a potent bio-insecticidal effect. BA may be a promising eco-friendly alternative to control T. castaneum due to its safety and authorization by the EFSA (European Food Safety Authority)

Acaricidal Activity of Tea Tree and Lemon Oil Nanoemulsions against Rhipicephalus annulatus

Tick infestation is a serious problem in many countries since it has an impact on the health of animals used for food production and pets, and frequently affects humans. Therefore, the present study aimed to investigate the acaricidal effects of nanoemulsions of essential oils of Melaleuca alternifolia (tea tree, TT) and Citrus limon (lemon oil, CL) against the different stages (adult, eggs, and larvae) of deltamethrin-resistant Rhipicephalus annulatus ticks. Three forms of these oils were tested: pure oils, nanoemulsions, and a binary combination. Tea tree and lemon oil nanoemulsions were prepared, and their properties were assessed using a zeta droplet size measurement and a UV-Vis spectrophotometer. The results showed that TT and CL exhibited higher adulticidal effects in their pure forms than in their nanoemulsion forms, as demonstrated by the lower concentrations required to achieve LC50 (2.05 and 1.26%, vs. 12.8 and 11.4%, respectively) and LC90 (4.01% and 2.62%, vs. 20.8 and 19.9%, respectively). Significant larvicidal activity was induced by the TTCL combination, and LC50 was reached at a lower concentration (0.79%) than that required for the pure and nanoemulsion forms. The use of pure CL oil was found to have the most effective ovicidal effects. In conclusion, pure TT and CL have potent acaricidal effects against phenotypically resistant R. annulatus isolates. It is interesting that the activity levels of TT and CL EOs&rsquo; binary and nanoemulsion forms were lower than those of their individual pure forms

Synthesis of Carvacrol-Loaded Invasomes Nanoparticles Improved Acaricide Efficacy, Cuticle Invasion and Inhibition of Acetylcholinestrase against Hard Ticks

Carvacrol is a monoterpenoid phenol found in many essential oils that has antibacterial, antifungal and antiparasitic activities. Drug loaded-invasome systems are used to deliver drugs utilizing nanoparticles to improve bioavailability, efficacy, and drug release duration. As a result, the present study developed carvacrol-loaded invasomes and evaluated their acaricidal effect against Rhipicephalus annulatus (cattle tick) and Rhipicephalus sanguineus (dog tick). Carvacrol loaded-invasome (CLI) was prepared and characterized using UV/Vis spectrophotometer, zeta potential measurements, Scanning Transmission Electron Microscopy (STEM), Fourier Transform Infrared (FT-IR) Spectroscopy, and Differential Scanning Calorimetry Analysis. CLI (5%) induced significant mortality (100%) in R. annulatus adult ticks with LC50 of 2.60%, whereas the LC50 of pure carvacrol was 4.30%. Carvacrol and CLI were shown to have a significant larvicidal action on both tick species, with LC50s of 0.24 and 0.21% against R. annulatus and 0.27 and 0.23% against R. sanguineus, respectively. Carvacrol and CLI (5%) induced significant repellent activities for 24 h against R. annulatus and R. sanguineus, as evidenced by the rod method and the petri-dish selective area choice method, respectively. High-performance liquid chromatography (HPLC) demonstrated that the CLI form had 3.86 times the permeability of pure carvacrol. Moreover, carvacrol and CLI inhibited acetylcholinesterase activity and decreased glutathione and malonedealdehyde levels in the treated ticks. In conclusion, invasomes significantly improved adulticidal and repellency activities of carvacrol against both tick species

Carvacrol-loaded invasomes efficacy against multidrug resistant isolates of Enterobacteriaceae and housefly

The current study aimed to evaluate the antimicrobial activity of carvacrol-loaded invasomes (CLI) against multidrug-resistant (MDR) Enterobacteriaceae and its mechanical vector, the housefly. CLI were prepared and characterized in the laboratory. Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica subsp. enterica serovar Enteritidis, Salmonella enterica subsp. enterica serovar Typhimurium, and Klebsiella oxytoca were among the MDR enterobacteriaceae stains investigated. These strains were first isolated and identified from naturally infected chickens. The antibacterial activity of CLI against the MDR isolates was evaluated using the diffusion method. In addition, the insecticidal activity of CLI against housefly larvae and pupae was tested. The MDR index of all evaluated isolates was greater than 20%, indicating that they were all multidrug-resistant. CLI decreased the growth of all isolates except S. Typhimurium and P. aeruginosa at a dose of 0.0125%; however, pure carvacrol inhibited the growth of only Klebsiella oxytoca. Furthermore, both CLI and pure carvacrol inhibited Klebsiella oxytoca growth at different concentrations. CLI inhibited E. coli and S. enteritidis at lower concentrations than pure carvacrol, even at a doubled concentration. Carvacrol and CLI caused significant larval mortality even at low concentrations, with LC50 reached at concentartions of 2.54 and 2.19 µl/ml, respectively. Furthermore, at a low concentration of 3.125 µl/ml, both elicited a high percentage inhibition rate (PIR) in pupae. In conclusion, CLI demonstrated substantial antibacterial action, particularly against MDR isolates, as well as pesticide activity against houseflies.