Self-emulsifying drug delivery systems (SEDDS) containing Cymbopogon citratus essential oil: Enhancing the stability and acaricide efficacy against Rhipicephalus (Boophilus) microplus.

The objectives of this study were to develop a self-emulsifying drug delivery system (SEDDS) to enhance the stability and efficacy of Cymbopogon citratus essential oil or lemongrass oil (LEO) against cattle tick larvae and engorged females. The system with the highest oil loading in SEDDS was composed of LEO (23.33%w/w), Tween 80: SGKH 4000 in a 2:1 ratio as surfactant (66.67%w/w), and propylene glycol as co-surfactant (10%w/w). The selected SEDDS-LEO has a particle size of 18.78 nm with a narrow size distribution (polydispersity index of 0.27). Notably, the stability of SEDDS was superior to that of the original oil, both during long-term storage and under accelerated conditions. SEDDS-LEO at oil concentrations ranging from 1.458% to 5.833% w/v showed a significantly higher percentage of egg-laying reduction against adult ticks compared with the original oil at the same concentrations (p < 0.05). Furthermore, SEDDS-LEO demonstrated greater larvicidal efficacy than the original oil, with lower LC50 and LC90 values of 0.91 mg/mL and 1.20 mg/mL, respectively, whereas the original oil's LC50 and LC90 values were 1.17 mg/mL and 1.74 mg/mL, respectively. Our findings indicate that SEDDS-LEO is a promising candidate for use as an acaricide in the control of tick populations in dairy cattle.

Efficacy and safety of geranium-oregano-thymol formulations to control of dog tick Rhipicephalus sanguineus sensu lato under laboratory and field conditions.

The present study evaluated, in laboratory and field, the efficacy and safety of formulations of Pelargonium graveolens (geranium - G), Origanum majorana (oregano - O) commercial essential oils (EO) and thymol (T) to control of Rhipicephalus sanguineus sensu lato. In the laboratory, three formulas (A: 2% tween 80%, B: powder and C: nanoemulsion) by a mixture of these components (GOT) were prepared and evaluated, and the best one was used to assess its safety and field application against R. sanguineus s. l. on naturally infested dogs. Besides the major compounds of the EO used were identified. The results of the lab study showed that formula A (2.5 g of each G + O + T + 2% tween 80 to complete 100 mL) was significantly more effective than the other two formulas tested and exhibited highly effective adulticidal, larvicidal, and ovicidal activity against R. sanguineus s.l. Significant LC50 and LC90 values of GOT were evaluated (13.4 and 21.5 mg/mL, respectively) for the adulticidal activity, (2.81 and 4.46 mg/mL, respectively) for ovicidal activity and (2.44 and 4.45 mg/mL, respectively) for larvicidal activity. The safety of formula A has been proven by the absence of its cytotoxicity on a cell line of human epidermoid carcinoma. Citronella and carvacrol were the major compounds identified in the commercial essential oils of P. graveolens and O. majorana, respectively. Formula A was used in a field control trial for almost 8 months, during the tick infestation season (April to November, 2022). Fourteen naturally infested dogs were divided into two groups, each with seven dogs. One group received formula A spraying five times during an experiment that continued for 8 months, while the other group received treatment with commercially available malathion acaricide. The animals were sprayed on five occasions throughout the experiment (April, June, July, August, and September). The results showed a substantial percentage of effectiveness after the first application of formula A with a 99.3% reduction in tick count at day 28 post-application (PA). In the case of severe infestation 60 days after the first application of formula A (more than 180 ticks per dog), the second application was done, achieving an efficacy of 54.9% at day 3 PA, so an emergency spray was done at day 5 PA to combat the rest of the tick infestation, achieving efficacy of 99% after 3 days. Consequently, a regular spray (third, fourth, and fifth application) was done every 35 days. This regular spray revealed 100% effectiveness at 14 days PA. Biochemical parameters of treated dogs were evaluated to confirm the safety of formula A. Creatinine, ALT, and albumin of the dogs treated with formula A were within the normal range of dogs, while urea and AST were higher than the normal range. In conclusion, formula A can safely treat R. sanguineus s.l. infestations in dogs with regular application every 5 weeks.

Do combinations of fipronil, eugenol and carvacrol have synergistic effects against Rhipicephalus sanguineus?

The tick Rhipicephalus sanguineus is one of the main ectoparasites that affects dogs, causing direct and indirect damage to parasitized animals. Currently, infestation control is mainly carried out by using synthetic acaricidal drugs. However, a decrease in efficacy and an increase in resistance to the main therapeutic protocols against tick infestations have been increasingly reported and confirmed, a factor that has driven research into the potential acaricide activity of natural compounds, including in association with synthetic molecules. The aim of this work was to evaluate whether the combinations of fipronil (FIP) and eugenol (EUG), FIP and carvacrol (CAR), and EUG and CAR would have synergistic effects against immature and unfed adult stages of R. sanguineus through in vitro bioassays. Bioassays were carried out using the larval packet test (FAO 2004) adapted for nymphs and adults. The synergistic activity was explored by combining each solution, based on the estimated LC50, in a 1:1 ratio (FIP: EUG, FIP: CAR and EUG: CAR). CompuSyn software was used to evaluate the various pairwise combinations of FIP, EUG and CAR, checking if there was synergism or antagonism between them. FIP and EUG and FIP and CAR showed combination index (CIn) values above 1.45, indicating antagonism. The synergistic activity between EUG and CAR was verified against all unfed phases of R. sanguineus, since the CIn was below 0.70, a value that indicates synergism. The combination of fipronil with either eugenol or carvacrol presented antagonistic effects against R. sanguineus larvae. On the other hand, carvacrol and eugenol had excellent pharmacological synergism against all tick stages with mortality values in the range of 80 to 100%, including the adult stage, which is less susceptible than immature stages.

Effectiveness of a fixed-dose combination injectable (0.2 mg/kg doramectin + 6.0 mg/kg levamisole hydrochloride) against Rhipicephalus microplus and sucking lice infesting cattle.

Unmanaged tick and sucking lice infestations negatively impact the health and production potential of cattle. Described herein are two non-interference dose confirmation studies evaluating the efficacy of a single administration of a new fixed-dose combination injectable (FDCI) endectocide consisting of 0.2 mg/kg doramectin + 6.0 mg/kg levamisole hydrochloride, against either laboratory-induced Rhipicephalus microplus infestations in Australia or naturally acquired sucking lice (Linognathus vituli) infestations in the US. This FDCI is available as Dectomax V® in Australia and New Zealand and as Valcor® in the United States. To evaluate therapeutic efficacy against R. microplus, 12 calves were each exposed to 10 infestations of ∼5000 larvae per infestation between Days -24 and -2. Calves were either treated on Day 0 with the FDCI or left untreated (control). Additional R. microplus infestations of ∼5000 larvae were conducted on Day 2 and then three times weekly to also evaluate persistent efficacy of the FDCI. Tick collections were conducted daily from Day -3. Group mean live tick counts, egg production, and egg viability were analyzed for significant differences between the two groups. To determine efficacy of the FDCI against lice, 24 cattle with active sucking lice infestations based on Day -7 counts were allocated to two groups and treated on Day 0 with either saline (control) or the FDCI. Lice counts were conducted weekly from Day 14 through 42 and again on Day 56. Mean group lice counts on each count day were compared between treatment groups. In the R. microplus study presented here, cattle in Queensland, Australia treated with the FDCI (Dectomax V®) showed > 90 % reduction in tick counts based on arithmetic means within 48 h of treatment when compared to untreated cattle, and counts were > 95 % reduced from post-treatment Day 5 through Day 30. In the sucking lice study conducted in the US, the FDCI (Valcor®) displayed 100 % efficacy against sucking lice infestations (L. vituli) from first count day (Day 14 post-treatment) through Day 35 and then 99.9 % efficacy through Day 56 post-treatment. No treatment-related adverse events were reported for cattle in either study. Using R. microplus and sucking lice as representative ectoparasites, these studies demonstrate the ectoparasite activity of doramectin is retained in the new FDCI.

Ocimum gratissimum essential oil and eugenol against Ctenocephalides felis felis and Rhipicephalus sanguineus: In vitro activity and residual efficacy of a eugenol-based spray formulation.

Fleas and ticks are among the main ectoparasites that affect pets. The indiscriminate and incorrect use of chemical antiparasitics may be related to increased insect resistance and environmental contamination, requiring prospection for active ingredients that are less harmful to animals, humans and the environment. The use of essential oils and their isolated compounds has been reported as a potential alternative to synthetic antiparasitics, but there is a lack of studies involving the design and development of stable and safe natural products-based formulations. Therefore, the aim of this study was to establish LC50 and LC90 of Ocimum gratissimum essential oil and eugenol on immature stages and adults of Ctenocephalides felis felis and Rhipicephalus sanguineus; and to design and to determine the in vitro efficacy and residual effect of a natural product-based spray formulation for flea and tick control in pets. Bioassays were carried out according to the filter paper impregnation technique for fleas and through the larval packet test for ticks. O. gratissimum essential oil and eugenol presented pulicidal and acaricidal activity in vitro against immature stages and adults of C. felis felis and immature stages of R. sanguineus. The greater potency of eugenol against fleas and ticks led to the choice of eugenol as the active ingredient in the pharmaceutical form developed. The developed eugenol-based sprays presented adequate physical and chemical characteristics and stability, had pulicidal and acaricidal efficacy after 24 h and residual effect against fleas for up to 48 days.

Successive treatments with ivermectin (3.15%) to control the tick Rhipicephalus (Boophilus) microplus in cattle: Pharmacokinetic and efficacy assessment.

This study aimed to evaluate the pharmacokinetics, the potential accumulation in the body of treated animals and the efficacy of ivermectin long-acting formulation (3.15%) against the cattle tick Rhipicephalus (Boophilus) microplus in a scheme of three successive treatments. Fifteen 12-month-old heifers, naturally infested with R. microplus, were divided into two groups (G). Cattle from GI (n = 10) were subjected to three treatments with ivermectin 3.15% (IVOMEC GOLD®, Merial Argentina S.A.) at a rate of 1 mL/50 kg on days 0, 35, and 70. Cattle from GII (n = 5) were not treated. From day 1 to 202 post-treatment blood samples were taken to measure ivermectin concentrations by HPLC and female ticks (4.5-8 mm) were counted to evaluate the efficacy of the treatment. The level of tick resistance to ivermectin was evaluated before and after finishing the scheme of successive treatments by larval immersion test (LIT) bioassay from engorged females collected from GI. The area under the concentration vs. time curves (AUC0-35d) obtained post-second treatment was 1.51 ± 0.39-fold higher than those observed post-first treatment (P<0.05). The mean plasma concentrations of ivermectin 3.15% at 20 days after the first, second and third treatment were 17.0, 27.5 and 37.8 ng/mL, respectively (P<0.01). The elimination half-life of ivermectin post-third treatment was significantly longer than that was previously reported after a single dose (P<0.01). Values of therapeutic efficacy percentage reached 75.6% post-first treatment and between 95.9 and 100% after the second treatment. Ticks evaluated by LIT showed a significant increase in lethal concentrations after treatments. Although the efficacy level was high, the successive treatments with long-acting ivermectin formulation generate a significant accumulation of drug in plasma and could increase the levels of resistance to this drug in the tick population.

First report on efficacy of Citrus limetta seed oil in controlling cattle tick Rhipicephalus microplus in red Sahiwal calves.

The objective of the study was to evaluate the acaricidal activity of Citrus limetta seed oil (CLO) for controlling the cattle tick Rhipicephalus microplus. C. limetta seeds were collected as a waste product from different juice corners. CLO was obtained after extraction of seeds on soxhlet apparatus using n-hexane as solvent. It was characterized through Gas Chromatography-High Resolution Mass Spectroscopy (GC-HRMS) to determine the presence of active constituents. In vitro bioassays were performed using adult immersion test (AIT) and larval packet test (LPT). In vivo acaricidal efficacy of CLO was performed on red Sahiwal calves using ear bag method. Clinical safety of CLO was evaluated by observing haematological parameters and skin irritancy assay. Results of GC-HRMS showed that mainly fatty acids such as linoleic acid, stearic acid, oleic acid, palmitic acid, and linolenic acid were present in the CLO. CLO in the concentration of 125 mg/mL (CLO8) exhibited 100 % mortality in both AIT and LPT. CLO significantly (p < 0.001) reduced the number of ticks from 35 to 5.05 and 3.24 on 144 h after treatment with CLO7 and CLO8, respectively. CLO was found clinically safe without producing erythema and edema on skin. Haematological parameters such as haemoglobin (11.48 g/100 mL), total leucocytes count (4.32 106/cumm), total erythrocytes count (6.80 106/cumm), and packed cell volume (34.39 %) were normal and controlled. CLO may be used as effective and safe drug therapy for controlling R. microplus ticks.

Efficacy of a novel topical combination of esafoxolaner, eprinomectin and praziquantel against Ixodes ricinus and Ixodes scapularis in cats.

Esafoxolaner is a purified enantiomer of afoxolaner with insecticidal and acaricidal properties. It is combined with eprinomectin and praziquantel in a novel topical endectoparasiticide formulation for cats. The efficacy of this novel formulation was evaluated in three Ixodes ricinus and two Ixodes scapularis experimental studies, with comparable designs. In each study, cats were randomly allocated, based on a pre-treatment tick infestation and count, to a placebo control group or a group treated with the minimum recommended dose of the novel formulation. Cats were infested two days before treatment and weekly thereafter. Immediate efficacy was evaluated 48 h after treatment; persistent efficacy was evaluated 48 h after new weekly infestations for at least one month after the treatment (in one of the studies, the first two weeks of persistent efficacy against I. ricinus were not tested). Efficacy was calculated at each timepoint by comparison of arithmetic means of live ticks found in the control and the treated groups. In the three studies targeting I. ricinus, immediate and persistent efficacies ranged between 91% and 100% for five weeks. In the two studies targeting I. scapularis, immediate and persistent efficacies ranged between 95% and 100%, and 98% and 100% for one month, respectively. These studies provide robust evidence of efficacy of the novel topical formulation of esafoxolaner, eprinomectin and praziquantel against experimental I. ricinus and I. scapularis infestations for at least one month in cats.

TITLE: Efficacité d'une nouvelle association topique d'esafoxolaner, d'éprinomectine et de praziquantel contre Ixodes ricinus et Ixodes scapularis chez le chat. ABSTRACT: L'esafoxolaner est un énantiomère purifié de l'afoxolaner aux propriétés insecticides et acaricides. Il est associé à l'éprinomectine et au praziquantel dans une nouvelle formulation d'endectoparasiticide topique pour chats. L'efficacité de cette nouvelle formulation a été évaluée dans trois études expérimentales sur Ixodes ricinus et deux sur Ixodes scapularis, avec des conceptions comparables. Dans chaque étude, les chats ont été répartis au hasard, sur la base d'une infestation et d'un nombre de tiques avant le traitement, dans un groupe témoin placebo ou dans un groupe traité avec la dose minimale recommandée de la nouvelle formulation. Les chats ont été infestés deux jours avant le traitement et une fois par semaine par la suite. L'efficacité immédiate a été évaluée 48 heures après le traitement et l'efficacité persistante a été évaluée 48 heures après les nouvelles infestations hebdomadaires pendant au moins un mois après le traitement (dans l'une des études, les deux premières semaines d'efficacité persistante contre I. ricinus n'ont pas été testées). L'efficacité a été calculée à chaque temps d'évaluation par comparaison des moyennes arithmétiques des tiques vivantes trouvées dans les groupes témoins et traités. Dans les trois études ciblant I. ricinus, les efficacités immédiates et persistantes variaient entre 91 % et 100 % pendant cinq semaines. Dans les deux études ciblant I. scapularis, les efficacités immédiates et persistantes variaient respectivement entre 95 % et 100 % et 98 % et 100 % pendant un mois. Ces études fournissent des preuves solides de l'efficacité de la nouvelle formulation topique d'esafoxolaner, d'éprinomectine et de praziquantel contre les infestations expérimentales par I. ricinus et I. scapularis pendant au moins un mois chez le chat.

Efficacy of a novel topical combination of esafoxolaner, eprinomectin and praziquantel against Rhipicephalus sanguineus in cats.

Esafoxolaner is a purified enantiomer of afoxolaner with insecticidal and acaricidal properties. It is combined with eprinomectin and praziquantel in a novel topical endectoparasiticide formulation for cats. The efficacy of this novel formulation was assessed in an experimental study against induced infestation of Rhipicephalus sanguineus ticks. Twenty cats were randomly allocated to either a placebo control group or a treated group in a 1:1 ratio. Infested cats were treated topically once at the minimum recommended dose. The study was designed to assess curative efficacy 48 h after treatment and to test preventive efficacy 48 h after weekly infestations for 2 months. At each weekly infestation, all cats were infested with 25 male and 25 unfed female R. sanguineus ticks. At each tick count, at least 6 in 10 control cats had a retention of 13 (26%) or more live ticks, demonstrating adequate infestation throughout the study. Curative efficacy on existing tick infestation was 90%; preventive efficacy over the following 6 weeks was at least 96%.

TITLE: Efficacité d'une nouvelle association topique d'esafoxolaner, d'éprinomectine et de praziquantel contre Rhipicephalus sanguineus chez le chat. ABSTRACT: L'esafoxolaner est un énantiomère purifié d'afoxolaner, aux propriétés insecticides et acaricides. Il est combiné à éprinomectine et praziquantel dans une nouvelle formulation topique endectoparasiticide pour chats. L'efficacité de cette nouvelle formulation a été testée lors d'une étude contre des infestations expérimentales avec des tiques Rhipicephalus sanguineus. Vingt chats ont été répartis au hasard soit dans un groupe témoin placebo soit dans un groupe traité (rapport 1:1). Les chats infestés ont été traités par voie topique une fois à la dose minimale recommandée. L'étude a été conçue pour une évaluation de l'efficacité curative 48 heures après traitement et pour des évaluations d'efficacité préventive 48 heures après chaque infestation hebdomadaire pendant 2 mois. À chaque infestation hebdomadaire, tous les chats étaient infestés par 25 mâles et 25 femelles de R. sanguineus, non nourris. À chaque comptage, au moins 6 chats sur 10 du groupe placebo contrôle étaient infestés avec au moins 13 (26 %) tiques vivantes, ce qui a validé le modèle d'infestation. L'efficacité curative sur tiques présentes avant traitement a été de 90 %, l'efficacité préventive durant les six semaines suivantes a été d'au moins 96 %.

Efficacy of a novel topical combination of esafoxolaner, eprinomectin and praziquantel against Amblyomma americanum in cats.

Esafoxolaner, a purified enantiomer of afoxolaner with insecticidal and acaricidal properties, is combined with eprinomectin and praziquantel in NexGard® Combo, a novel topical endectoparasiticide product for cats. The efficacy of this novel formulation was assessed in two experimental studies against induced infestations with Amblyomma americanum, a tick species of major importance, highly prevalent in a large southeastern quarter of the United States. In each study, 10 cats were randomly allocated to a placebo control group and 10 cats to a novel formulation treated group. Infested cats were treated topically once at the minimum recommended dose. Both studies were designed to test curative efficacy on existing infestation, 72 h after treatment, and to test preventive efficacy, 72 h after subsequent weekly (Study #1) or fortnightly (Study #2) infestations for one month. For each infestation, all cats were infested with 50 unfed adult A. americanum. At each tick count, in both studies, at least 8 in 10 placebo control cats were infested with 13 (26%) or more live ticks, demonstrating adequate infestation throughout the studies. Curative efficacy of the novel formulation was 99% in both studies; preventive efficacy was 92% and 100% for at least one month.

TITLE: Efficacité d'une nouvelle association topique d'esafoxolaner, d'éprinomectine et de praziquantel contre Amblyomma americanum chez le chat. ABSTRACT: L'esafoxolaner, un énantiomère purifié d'afoxolaner aux propriétés insecticides et acaricides, est associé à l'éprinomectine et au praziquantel dans NexGard® Combo, un nouvel endectoparasiticide topique pour chats. L'efficacité de cette nouvelle formulation a été évaluée dans deux études expérimentales contre les infestations induites par Amblyomma americanum, une espèce de tique d'importance majeure, très répandue dans un grand quart sud-est des États-Unis. Dans chaque étude, dix chats ont été répartis au hasard dans un groupe témoin placebo et dix chats dans un groupe traité par une nouvelle formulation. Les chats infestés ont été traités une fois par voie topique à la dose minimale recommandée. Les deux études ont été conçues pour tester l'efficacité curative sur une infestation existante, 72 heures après le traitement, et pour tester l'efficacité préventive, 72 heures après des infestations hebdomadaires (étude n° 1) ou bimensuelles (étude n° 2) pendant un mois. Pour chaque infestation, tous les chats étaient infestés par 50 A. americanum adultes non nourris. À chaque décompte de tiques, dans les deux études, au moins 8 chats sur 10 du groupe témoin placebo étaient infestés de 13 (26 %) ou plus tiques vivantes, ce qui démontre une infestation adéquate tout au long des études. L'efficacité curative de la nouvelle formulation était de 99 % dans les deux études, l'efficacité préventive était de 92 % et 100 % pendant au moins un mois.

Control of Rhipicephalus annulatus resistant to deltamethrin by spraying infested cattle with synergistic eucalyptus essential oil-thymol-deltamethrin combination.

The current study investigated the synergistic effect of combinations containing deltamethrin (D), Eucalyptus essential oil (E), and the thyme essential oil component thymol (T), against a field population of Rhipicephalus annulatus in Egypt that was characterized to be resistant to D. Solutions of T, E, or TE at concentrations of 1.25-5% were combined with 5% deltamethrin at different dilutions (0.25-2 mL/L). Results of the adult immersion test used to estimate the in vitro acaricidal activity of these combinations at 5% yielded LC50 values for D, E-D, T-D, and TE-D of 3.87 mL/L, 3.89 mL/L, 0.14 mL/L, and 0.05 mL/L, respectively. Biochemical analyses using whole-body homogenate of ticks from the in vitro tests revealed that the lowest acetylcholinesterase and glutathione peroxidase activity, and the maximum lipid peroxidation were recorded in ticks treated with 5% TE-D. Glutathione content significantly decreased (p ≤ 0.05) in all treated ticks. Three groups, each containing five cross breed cattle naturally infested with R. annulatus from the same area where resistance to D was detected, were sprayed twice at two-week intervals using 1 mL/L of 5% solutions of D, T-D, or TE-D. Overall efficacy of the D, T-D, and TE-D sprays by day 30 post-treatment was 21.6, 88.3, and 95 %, respectively. Ticks collected from infested cattle three days after treatment with the D spray deposited egg masses that were able to hatch, deposited small masses of eggs unable to hatch when exposed to the T-D spray, and laid few eggs that didn't hatch when sprayed with the TE-D combination. Values for liver and kidney function parameters were comparable in cattle before and after treatment with the combination sprays tested. The TE-D spray overcame the insensitivity to D of this R. annulatus population in Egypt, which also highlighted the significant synergistic effect of thymol on the acaricidal activity of deltamethrin observed in vitro. Acaricidal activity of the TE-D combination apparently has deleterious effects on multiple tick systems involving inhibition of acetylcholinesterase, increased lipid peroxidation, and oxidative stress. These findings document that combinations of natural and synthetic products can be part of integrated management solutions to the problem with widespread resistance to pyrethroids like deltamethrin in populations of cattle ticks, including R. annulatus, around the world.

Metarhizium anisopliae sensu lato (s.l.) oil-in-water emulsions drastically reduced Rhipicephalus microplus larvae outbreak population on artificially infested grass.

Rhipicephalus microplus Canestrini, 1887 (Arachnida: Ixodidae) is a mandatory bloodsucking ectoparasite, and it is considered one of the main sanitary problems in livestock. In the development of new technologies for controlling ticks, Metarhizium anisopliae complex (M. anisopliae s. l.) Sorokin, 1883 (Ascomycota: Clavicipitaceae) have been shown to be an effective and safe alternative. However, when applied in the field, abiotic factors may directly influence their microbial activity, and different oily adjuvants enhance fungal efficacy, stability and viability under environmental conditions. Here, the efficacy of two Metarhizium anisopliae s.l. isolates (CG 148 and CG 347) were compared in mineral oil (MO) or vegetable oil (VO) emulsions to control cattle ticks under semi-natural conditions, as well as their persistence in the soil over time. Engorged female ticks were placed on the soil of grass pots previously treated or not with conidial oil-in-water emulsions. Both M. anisopliae s.l. oil-in-water emulsions tested were able to control R. microplus, achieving up to 100% daily efficacy, and remained viable in the soil for up to 60 days after treatment. These results show the prospective applicability of Metarhizium spp. to control the cattle tick and a real possibility for its control in the environment.

[Current status of pesticides against ticks].

Ticks can spread a variety of diseases and cause serious damage to animal husbandry. However, the existing insecticide and vaccine control methods have some disadvantages. In this paper, we review the research status of tick pesticides, including the chemical pesticides and non-chemical pesticides (Chinese herbal medicine, nanometer material, virus, fungus and bacterium pesticides), and analyze the disadvantages of the existing researches on pesticides against ticks, in order to provide a theoretical reference for establishing high-efficient and safety tick control methods.

In vivo effect of diflubenzuron, administered via mineral salt supplementation, against Haematobia irritans and Rhipicephalus microplus parasitizing cattle / Efeito in vivo do diflubenzuron, administrado via sal mineral, contra Haematobia irritans e Rhipicephalus microplus parasitando bovinos

Abstract This study involved two field trials with the aim of evaluating the efficacy of diflubenzuron, via mineral supplementation, against Haematobia irritans parasitizing cattle. Concomitantly with the main trial, a stall test was conducted to ascertain the effects of a different formulation with the same active ingredient against Rhipicephalus microplus, along with the action of diflubenzuron on the reproductive parameters of R. microplusfemales that had naturally detached from cattle. Against H. irritans, it was observed that the efficacy indexes fordiflubenzuron were low (≤ 31.3% or 44.6%) or null (0.0%) throughout the study. The anti- R. microplus efficacy of diflubenzuron, at weekly intervals, ranged from 0.0 to 13.7% over the entire experimental period. Null efficacy (0.0%) was registered for diflubenzuron in relation to the reproductive parameters of R. microplusfemales that had naturally detached from cattle. The different diflubenzuron formulations, administered via mineral salt supplementation, did not show satisfactory efficacy indexes against H. irritans and R. microplus parasitizing cattle, within the experimental design of the present study. In addition, this agent did not present any deleterious effects on the reproductive parameters of R. microplus females.

Resumo O objetivo deste estudo foi avaliar a eficácia do diflubenzuron, administrado via suplementação mineral, contra Haematobia irritans parasitando bovinos, em dois testes à campo. Concomitantemente, foi realizado testes em estábulo para determinar os efeitos de uma formulação diferente, com o mesmo princípio ativo, contra Rhipicephalus microplus , bem como a ação do diflubenzuron nos parâmetros reprodutivos de fêmeas de R. microplus recolhidas após desprendimento natural do hospedeiro bovino. Contra H. irritans, foi observado que foram baixos (≤ 31,3% ou 44,6%) ou nulos (0,0%) os índices de eficácia do diflubenzuron. A eficácia anti-R. microplus do diflubenzuron, observada em intervalos semanais, variaram de 0,0% a 13,7% durante todo o período experimental. Com relação aos parâmetros reprodutivos das fêmeas de R. microplus recolhidas, foi observada eficácia nula (0,0%) para o diflubenzuron. Conclui-se que as diferentes formulações administradas via sal mineral no atual estudo, contra H. irritans e R. microplus parasitando bovinos, não apresentaram eficácia satisfatória. Este agente também não mostrou efeito deletério sobre os parâmetros reprodutivos de fêmeas de R. microplus.

In vivo efficacy of a biotherapic and eugenol formulation against Rhipicephalus microplus.

The control of Rhipicephalus microplus is essential to prevent cattle discomfort and economic losses. However, increased resistance and acaricides inefficiency lead producers to adopt strategies that could result in the accumulation of chemical residues in meat and milk with possibilities of poisoning in animals and people. This scenario demonstrates the necessity of research into the identification of novel, effective and environmentally safe therapeutic options for cattle tick control. The objectives of this study were to develop and assess the efficacy of R. microplus biotherapic and of 5% eugenol for the control of R. microplus in artificially infested calves. Eighteen male 6-month-old Holstein calves were divided into three groups of six animals. In Group 1, the animals did not receive medication (control group); in Group 2, the animals received 1 mL of R. microplus biotherapic at dilution 6CH (centesimal Hahnemannian), orally administered twice daily. And in Group 3, they received a single application of eugenol 5% in the pour-on formulation. The median efficacy for biotherapy and eugenol 5% was respectively 10.13 and 13.97%; however, upon analyzing reproductive efficiency, it is noteworthy that the biotherapic had 45.86% efficiency and was superior to the action of eugenol (12.03%) after 37 days of treatment. The ultrastructural study provided information about the effects of R. microplus biotherapic on the ovaries of engorged females and showed disorganization in the deposition of the oocyte exochorion. The results suggest hatchability inhibition of larvae, interference in R. microplus reproduction and future possibilities for eco-friendly control of R. microplus with biotherapic 6CH.

The intravenous and oral pharmacokinetics of afoxolaner and milbemycin oxime when used as a combination chewable parasiticide for dogs.

The pharmacokinetics of afoxolaner and milbemycin oxime (A3 and A4 forms) in dogs were evaluated following the oral administration of NexGard Spectra® (Merial), a fixed combination chewable formulation of these two active pharmaceutical ingredients. Absorption of actives was rapid at levels that provide the minimum effective doses of 2.5 mg/kg and 0.5 mg/kg of afoxolaner and milbemycin oxime, respectively. The time to maximum afoxolaner plasma concentrations (tmax ) was 2-4 h. The milbemycin tmax was 1-2 h. The terminal plasma half-life (t1/2 ) and the oral bioavailability were 14 ± 3 days and 88.3% for afoxolaner, 1.6 ± 0.4 days and 80.5% for milbemycin oxime A3 and 3.3 ± 1.4 days and 65.1% for milbemycin oxime A4. The volume of distribution (Vd ) and systemic clearance (Cls) were determined following an IV dose of afoxolaner or milbemycin oxime. The Vd was 2.6 ± 0.6, 2.7 ± 0.4 and 2.6 ± 0.6 L/kg for afoxolaner, milbemycin oxime A3 and milbemycin oxime A4, respectively. The Cls was 5.0 ± 1.2, 75 ± 22 and 41 ± 12 mL/h/kg for afoxolaner, milbemycin oxime A3 and milbemycin oxime A4, respectively. The pharmacokinetic profile for the combination of afoxolaner and milbemycin oxime supports the rapid onset and a sustained efficacy for afoxolaner against ectoparasites and the known endoparasitic activity of milbemycin oxime.

Efficacy of Tagetes minuta (Asteraceae) essential oil against Rhipicephalus sanguineus (Acari: Ixodidae) on infested dogs and in vitro.

Ticks from Rhipicephalus sanguineus complex are widely distributed in the world and one species from this complex is the most common tick on dogs in Brazil, notably in urban areas. This tick is a vector of several diseases. Among others it transmits the agent of canine Ehrlichiosis, a major dog infectious disease and the agent of Rocky Mountain spotted fever. This tick can spread rapidly and develop intolerable infestations within no time. Currently tick control is done with acaricides and demand for such drugs has grown fast. However, R. sanguineus has already developed resistance to the main active compounds and the development of new acaricides is necessary. Many essential oils of plants have acaricidal effect and may be an important source of molecules for the synthesis of new acaricide products. In this study, we evaluated the effectiveness of a new herbal phytotherapic, consisting of the essential oil of Tagetes minuta L., against R. sanguineus in vitro and on dogs undergoing experimental infestations. The product displayed 100% efficacy against larvae, nymphs and adults of the tick on all tested conditions.

Evaluation of tea tree oil for controlling Rhipicephalus microplus in dairy cows.

Our research aimed to test the effects of Melaleuca alternifolia oil (pure and in nanocapsules) in the control of Rhipicephalus microplus in dairy cattle. For this purpose, the in vivo studies used 15 cows distributed in three different groups with the same number of animals. Five cows remained untreated (Group A), representing the control group; other five cows were sprayed with TTO (at 5%) in its pure form (Group B); and five cows were sprayed with nanocapsules of TTO (at 0.75%) (Group C). On days 1 and 4 post-treatments (PT), all cows had their ticks counted. On day 1 PT, two ticks from each cow were collected to evaluate the effect of the treatment on ticks reproduction (in vitro assays). The pure form of TTO caused a significant reduction (P<0.05) in the number of ticks from the Group B compared to the Group A on day 4 PT. However, there was no significant difference in the number of ticks on cows from Groups A and C after treatment (P>0.05). Treatment with TTO in nanocapsules (Group C) interfered with R. microplus reproduction, leading to lower oviposition by female ticks and hatchability (34.5% of efficacy). On the other hand, TTO oil (Group B) did not interfere on ticks reproduction, i.e. showed higher hatchability than the control group. Therefore, it is possible to conclude that pure TTO has an acaricidal effect in dairy cows, in addition to an effect on ticks reproduction when used its nanocapsulated form.

Invitro acaricidal activity of ethnoveterinary plants and green synthesis of zinc oxide nanoparticles against Rhipicephalus (Boophilus) microplus.

The present study was designed to investigate the invitro acaricidal effects of seven ethnoveterinary plants, zinc acetate and green synthesized zinc oxide nanoparticles against the Southern cattle tick, Rhipicephalus (Boophilus) microplus. The selected ethnoveterinary plants were extracted using ethanol and aqueous (water) solvents at 0.02mg/ml and 0.04mg/ml concentrations. Of these seven plants, Lobelia leschenaultiana showed the highest percentage of tick mortality. The ethanol extracts of L. leschenaultiana showed 93.33% mortality at 0.04mg/ml and its LC50 was 0.05mg/ml. However, zinc acetate exhibited 70% mortality at 0.04mg/ml (LC50: 0.0192mg/ml). Further, we synthesized ZnO nanoparticle using the leaf extracts of L. leschenaultiana and zinc acetate as the precursor material to control R. (B.) microplus. The structural characterization of the synthesized ZnO nanoparticles (Ll-ZnO NPs) was performed by UV-vis spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and transmission electron microsopy (TEM). UV-vis spectra showed the absorption band at 383nm. XRD analysis clearly showed the crystalline nature of Ll-ZnO NPs with various Bragg's reflection peaks at 100, 002, 101, 102, 110, 103, 200, 201 and 202 planes. FTIR analysis showed the possible functional groups of Ll-ZnO NPs with strong band at 3420.63 and 2922.48cm(-1). SEM and TEM analysis revealed that the Ll-ZnO NPs were spherical and hexagonal in shape with particle size ranging between 20 and 65nm. The mortality of R. (B.) microplus after treatment with Ll-ZnO NPs was 35, 57.5 and 82.5% at 0.001, 0.002 and 0.004mg/ml. On the otherhand, 100% mortality of R. (B.) microplus was observed at 0.008mg/ml (LC50: 0.0017mg/ml). The results indicated that the Ll-ZnO NPs have good acaricidal properties compared to L. leschenaultiana leaf extract and zinc acetate.

Repellency and acaricidal efficacy of a new combination of fipronil and permethrin against Ixodes ricinus and Rhipicephalus sanguineus ticks on dogs.

BACKGROUND: A blinded, controlled laboratory study was conducted to assess the repellency and acaricidal activity of a topical spot on formulation, a combination of fipronil and permethrin, against Ixodes ricinus and Rhipicephalus sanguineus ticks on dogs. METHODS: A group of 16 adult mixed breed dogs were randomly divided into treatment and control groups based on pre-treatment live tick counts. On Day 0, the topical spot on formulation of fipronil + permethrin (commercialized under the name Frontline Tri-Act®/Frontect®) was administered to dogs in the treatment group at the minimum recommended dose of 0.1 mL/kg, corresponding to 6.76 mg fipronil/kg and 50.48 mg/kg permethrin. Tick infestations were performed with I. ricinus (50 females, 50 males) and R. sanguineus (25 females, 25 males) on each dog on Days 2, 7, 14, 21, and 28. Dogs were sedated prior to exposure and confined to crates for approximately 4 h following tick challenge. Ticks were released next to the sedated dogs and tick counts were performed at 4 h and 24 h after the start of exposure for tick counts and removal. RESULTS: Repellency at 4 h against I. ricinus was 72.6, 96.3, 92.8, 89.0, and 88.7 % on Days 2, 7, 14, 21, and 28, respectively. Repellency was 100 % 24 h after exposures on Days 2, 7, and 14 and 99.6 % after exposures on Days 21 and 28. For R. sanguineus, repellency at 4 h was 78.0, 96.8, 91.5, 88.0, and 56.8 % on Days 2, 7, 14, 21, and 28, respectively. Repellency at 24 h was 98.6, 100, 98.7, 96.1, and 95.1 % for exposures on Days 2, 7, 14, 21, and 28, respectively. For I. ricinus, acaricidal efficacy recorded at 4 h was ≥ 91.1 % during the full month and was ≥ 99.5 % for the full month when counted at 24 h. Acaricidal efficacy against R. sanguineus was ≥ 94.7 % at 4 h from Day 2 to Day 21 and was 71.4 % on Day 28. Acaricidal efficacy at 24 h, was > 97.7 % during the month. Tick counts were statistically significantly reduced in treated dogs at all time-points during the study. CONCLUSIONS: A combination of fipronil and permethrin was highly effective at rapidly repelling and killing both I. ricinus and R. sanguineus ticks on dogs for at least 4 weeks, with a significant effect at 4 and 24 h after tick exposure.