Acaricidal activity and enzyme inhibitory activity of active compounds of essential oils against Psoroptes cuniculi.

Plant essential oils and its chemical compositions are commonly applied in medicinal and other industries due to their broad advanced pharmacological activities. In the present study, we systematically evaluated the acaricidal activities of twelve compounds of essential oils against Psoroptes cuniculi in vitro and in vivo. In addition, to support the clinic uses, their toxicities against immortalized human keratinocytes (HaCaT) and human liver cells (HL-7702) and skin irritation were studied for evaluating the liver and skin safety. The possible mechanism of action of certain chemical were investigated by determining the inhibitory activities against cytochrome P450 (P450) acetylcholinesterase (AChE) and glutathione-S-transferase (GST). Among all tested compounds, eugenol exhibited the best acaricidal activity with LC50 value of 56.61 µg/ml in vitro. Meanwhile, after the treatment of eugenol for five times within 10 days, the P. cuniculi were eliminated in the naturally infested rabbits, no skin irritation was found in rabbits treated by eugenol. Moreover, eugenol presented no or weak cytotoxicity against HaCaT cells and HL-7702 cells with IC50 values of greater than 100 µg/ml. Furthermore, the moderate inhibitory activities of eugenol against mites P450 and AChE were demonstrated. Above results indicated that eugenol presented the promising acaricidal activity against P. cuniculi in vitro and in vivo, is safe for both humans and animals at the given doses. This work lays the foundation for the development of eugenol as an environmentally friendly acaricide agent.

Preclinical Study of Single-Dose Moxidectin, a New Oral Treatment for Scabies: Efficacy, Safety, and Pharmacokinetics Compared to Two-Dose Ivermectin in a Porcine Model.

BACKGROUND: Scabies is one of the commonest dermatological conditions globally; however it is a largely underexplored and truly neglected infectious disease. Foremost, improvement in the management of this public health burden is imperative. Current treatments with topical agents and/or oral ivermectin (IVM) are insufficient and drug resistance is emerging. Moxidectin (MOX), with more advantageous pharmacological profiles may be a promising alternative. METHODOLOGY/PRINCIPAL FINDINGS: Using a porcine scabies model, 12 pigs were randomly assigned to receive orally either MOX (0.3 mg/kg once), IVM (0.2 mg/kg twice) or no treatment. We evaluated treatment efficacies by assessing mite count, clinical lesions, pruritus and ELISA-determined anti-S. scabiei IgG antibodies reductions. Plasma and skin pharmacokinetic profiles were determined. At day 14 post-treatment, all four MOX-treated but only two IVM-treated pigs were mite-free. MOX efficacy was 100% and remained unchanged until study-end (D47), compared to 62% (range 26-100%) for IVM, with one IVM-treated pig remaining infected until D47. Clinical scabies lesions, pruritus and anti-S. scabiei IgG antibodies had completely disappeared in all MOX-treated but only 75% of IVM-treated pigs. MOX persisted ~9 times longer than IVM in plasma and skin, thereby covering the mite's entire life cycle and enabling long-lasting efficacy. CONCLUSIONS/SIGNIFICANCE: Our data demonstrate that oral single-dose MOX was more effective than two consecutive IVM-doses, supporting MOX as potential therapeutic approach for scabies.

Chemical and Plant-Based Insect Repellents: Efficacy, Safety, and Toxicity.

Most emerging infectious diseases today are arthropod-borne and cannot be prevented by vaccinations. Because insect repellents offer important topical barriers of personal protection from arthropod-borne infectious diseases, the main objectives of this article were to describe the growing threats to public health from emerging arthropod-borne infectious diseases, to define the differences between insect repellents and insecticides, and to compare the efficacies and toxicities of chemical and plant-derived insect repellents. Internet search engines were queried with key words to identify scientific articles on the efficacy, safety, and toxicity of chemical and plant-derived topical insect repellants and insecticides to meet these objectives. Data sources reviewed included case reports; case series; observational, longitudinal, and surveillance studies; and entomological and toxicological studies. Descriptive analysis of the data sources identified the most effective application of insect repellents as a combination of topical chemical repellents, either N-diethyl-3-methylbenzamide (formerly N, N-diethyl-m-toluamide, or DEET) or picaridin, and permethrin-impregnated or other pyrethroid-impregnated clothing over topically treated skin. The insecticide-treated clothing would provide contact-level insecticidal effects and provide better, longer lasting protection against malaria-transmitting mosquitoes and ticks than topical DEET or picaridin alone. In special cases, where environmental exposures to disease-transmitting ticks, biting midges, sandflies, or blackflies are anticipated, topical insect repellents containing IR3535, picaridin, or oil of lemon eucalyptus (p-menthane-3, 8-diol or PMD) would offer better topical protection than topical DEET alone.

Isotherapic for the control of the cattle tick

Parasitism constitutes one of the major problems that affect the livestock. Commercial acaricides can propitiate drug resistance and residues in the environment and animals. This study aimed to evaluate the control of cattle ticks by using the isotherapics. These drugs were prepared using Rhipicephalus (Boophilus) microplus. The dilution and agitations were performed according to the homeopathic pharmacopoeia. By the immersion technique of adults, 50 teleogines were distributed into five treatments: 12cH and 32cH isotherapic, negative control, positive (ivermectin 1%) and vehicle control. The results were evaluated by the rate of mortality, egg production, hatchability rate, estimated reproduction, and the efficacy of the products. In addition, 16 Jersey females cows were subjected to 15mL pour on, of the following treatments: 12cH and 32cH isotherapic and vehicle control. The count of ticks was performed by the simple method on days 0, 15, 21, 42, 63, 84 and 105, post treatments. It was used the Wilcoxon test and Bonferroni method. Both isotherapics treatments showed efficacy at in vitro tests. The 12cH medication presented better results: 10% of mortality rate on the first day of life, maintaining 20% from the second to the 13th day. Additionally, it was observed 20% of egg production, hatching rate of 0.0038% and 99.39% of product effectiveness. However, the in vivo tests showed no satisfactory results for these evaluated conditions, although it was verified a tendency to decreasing the infestation.

Isotherapic for the control of the cattle tick

Parasitism constitutes one of the major problems that affect the livestock. Commercial acaricides can propitiate drug resistance and residues in the environment and animals. This study aimed to evaluate the control of cattle ticks by using the isotherapics. These drugs were prepared using Rhipicephalus (Boophilus) microplus. The dilution and agitations were performed according to the homeopathic pharmacopoeia. By the immersion technique of adults, 50 teleogines were distributed into five treatments: 12cH and 32cH isotherapic, negative control, positive (ivermectin 1%) and vehicle control. The results were evaluated by the rate of mortality, egg production, hatchability rate, estimated reproduction, and the efficacy of the products. In addition, 16 Jersey females cows were subjected to 15mL pour on, of the following treatments: 12cH and 32cH isotherapic and vehicle control. The count of ticks was performed by the simple method on days 0, 15, 21, 42, 63, 84 and 105, post treatments. It was used the Wilcoxon test and Bonferroni method. Both isotherapics treatments showed efficacy at in vitro tests. The 12cH medication presented better results: 10% of mortality rate on the first day of life, maintaining 20% from the second to the 13th day. Additionally, it was observed 20% of egg production, hatching rate of 0.0038% and 99.39% of product effectiveness. However, the in vivo tests showed no satisfactory results for these evaluated conditions, although it was verified a tendency to decreasing the infestation.(AU)

Efficacy of Strychnos spinosa (Lam.) and Solanum incanum L. aqueous fruit extracts against cattle ticks.

The efficacy of Solanum incanum and Strychnos spinosa aqueous fruit extracts was evaluated against cattle ticks in on-station experiments and laboratory tick bioassays. In the on-station experiment using cattle, fruit extracts were applied at three concentrations 5, 10, and 20 % (w/v) and compared with a commercial acaricide, Tickbuster (amitraz) spray (positive control) and no treatment (negative control). The treatments were applied at weekly intervals for 6 weeks as surface sprays on 32 Mashona cattle in a completely randomized design experiment. Ticks on individual cattle were identified, counted, and recorded daily. Peripheral blood samples were collected for parasite screening. In the laboratory, tick bioassays were conducted at four concentrations, 5, 10, 20, and 40% (w/v) fruit extracts compared to Tickbuster (amitraz) spray (positive control) and distilled water (negative control). The extracts were incubated with Rhipicephalus (Boophilus) decoloratus tick larvae and mortalities for each treatment level recorded after 24 and 48 h. The 5% Solanum incanum treatment had higher efficacy ratio (P < 0.05) than the other fruit extract concentrations of the same plant species. Efficacy ratio was higher (P < 0.05) in the 5% S. spinosa-treated cattle than in the untreated control but lower (P < 0.05) than that for the amitraz treatment. The bioassays indicated that there was a high efficacy ratio for the lowest fruit extract concentrations when ticks were exposed to acaricidal treatments for 48 h compared to 24 h. Overall, the results indicate that Solanum incanum and Strychnos spinosa individually have some acaricidal effect.

Age-related changes in the behavioural response of honeybees to Apiguard®, a thymol-based treatment used to control the mite Varroa destructor.

The parasitic mite Varroa destructor is responsible for heavy losses in honey bee colonies and represents a major threat to the beekeeping industry. Essential oils offer an attractive alternative to the use of synthetic chemicals for the control of varroa. Amongst them, thymol appears to be particularly promising. However, treatments using thymol as their active substance, such as the gel formulation Apiguard(®), are suspected to have adverse effects on honey bee colonies. In this study, laboratory assays are used to investigate the effects of Apiguard(®) exposure on honey bee behaviour. Our results reveal that honey bee responses to this anti-varroa treatment change with honey bee age. While 2-day-old bees respond neutrally to Apiguard(®), older bees generally avoid the Apiguard(®) gel. Responses of forager bees were particularly striking. Foragers appear to be repelled by Apiguard(®). Touching their antennae with Apiguard(®) induces robust fanning behaviour. Our data suggest, however, that forager bees exposed to Apiguard(®) in the hive can become habituated to this treatment. These results offer interesting new perspectives on the effects of Apiguard(®) on honey bee behaviour and serve to highlight age-related changes in honey bee responses to gustatory, as well as olfactory cues.

The efficacy of neem seed extracts (Tre-san, MiteStop on a broad spectrum of pests and parasites.

The paper summarizes the acaricidal and insecticidal effects of a patented neem seed extract when diluted 1:10 with shampoo or 1:20, 1:30, 1:33, 1:40, respectively, 1:66 with tap water. It was shown that a broad range of pests and parasites, such as house dust mites, poultry mites, harvest mites, Ixodes and Rhipicephalus ticks, cat fleas (adults, larvae), bed bugs (all stages), head lice and mallophaga, cockroaches (genera Blatta, Blattella, Gomphadorhina), raptor bugs (Triatoma), and even food-attacking beetle (Tenebrio molitor) might be controlled with this extract, which is available as Tre-san (against house dust mites) and MiteStop (against mites, ticks, insects of any kind) to become water diluted or as Wash Away Louse or Picksan LouseStop being diluted in a shampoo. Tests on skin compatibility proved that there are no skin irritations during or after use. However, some target species are less sensible (beetles, Triatoma stages, fly maggots), while the specimens of the other species cited above were successfully killed even at low concentrations of the extract.