Efficacy of hydroethanolic extract of Randia aculeata seed against the southern cattle tick Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) on naturally infested cattle under field conditions.

The cattle tick Rhipicephalus (Boophilus) microplus is a major problem of concern for cattle industry in tropical and subtropical areas. Control of cattle tick is based mainly on the use of chemical acaricides, which has contributed to the emerging problem of selection of resistant tick lineages. Plants have been used as an alternative to conventional acaricidal drugs. On the other hand, the acaricidal activity of hydroethanolic extract of Randia aculeata seed (EHRA) has been demonstrated against R. microplus under laboratory conditions. However, the utility of EHRA seed as a potential acaricidal needs to be determined under field conditions. For this reason, the aim of this study was to evaluate the efficacy of the EHRA against R. microplus sprayed on naturally infested calves, determine the effect of the EHRA seed on acetylcholinesterase activity in R. microplus larval and identify the chemical composition of EHRA. Forty-five male calves were divided in three groups and treated with: G1 water; G2 EHRA 20% w/v and G3 coumaphos 0.2% v/v. Acetylcholinesterase (AChE) activity in R. microplus larvae was determined by a colorimetric assay. The chemical composition of EHRA was accessed through HPLC/MS. Significantly fewer ticks were observed after 24 h on the treated group compared to control group. EHRA significantly inhibited in vitro AChE activity in R. microplus at all tested concentrations. Chlorogenic acid, vanillinic acid, p-coumaric acid, caffeic acid. rutin, quercetin, (-)-epicatechin, 4-hydroxybenzoic acid, quercetin, vanillin, 2,4-dimethoxy-6-methylbenzoic acid, scopoletin and ferulic acid were identified in the extract. The results provided new data for the elucidation of the mechanisms of EHRA acaricide action and to further evaluate the use as a new alternative control agent against R. microplus under in vivo conditions.

Establishment of antitick efficacy of a phytoformulation prepared from Annona squamosa leaf extracts for the management of acaricide resistant tick infestations on cattle.

To combat the problem of acaricide resistance in ticks, efforts have been made to develop eco-friendly herbal acaricides which are safe for animal use with no possibilities of evoking environment and residual toxicity. In the present study, the acaricidal properties of a commonly available plant, Annona squamosa have been established to develop a novel antitick phytoformulation using leaf extract, suitable solvents and emulsifier for managing resistant tick infestations in animals. The quality control of the safe and stable phytoformulation using Rutin as a major constituent was maintained by HPTLC profiling. Several phytformulations (A-E) were prepared and formulation 'C' is identifried as the most effective showing 52.5-75% antitick activity against in vitro treated resistant strains of R. microplus (IVRI-IV and V) with 33.8-40.2% inhibition of oviposition while 65-85% mortality against multiacaricide resistant field populations. The phytoformulation provided 70.4% efficacy after first larval challenge in experimentally infested animals. The field efficacy of the formulation in different multilocational field trials was 68.53-77.8%. The detail antitick efficacy of the formulation along with safety and stability are explained as a component of antitck technology to manage resistant tick problem in livestock.

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.

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.

Sublethal concentrations of acetylcarvacrol strongly impact oocyte development of engorged female cattle ticks Rhipicephalus microplus (Canestrini, 1888) (Acari: Ixodidae).

Rhipicephalus microplus, commonly known as southern cattle tick, causes huge economic losses in the cattle industry. Its infestation affects the production of meat and milk and causes discomfort to hosts. In addition, it is the vector of Babesia spp. and Anaplasma spp. The most frequent method used to control these parasites is through synthetic acaricides. However, their indiscriminate use can be toxic for hosts and environment as well as cause selection of resistant ticks. Plant extracts and essential oils emerge as promising alternatives to manage tick infestation. Carvacrol, an aromatic monoterpene extracted from plants, has recognized antimicrobial, antioxidant, insecticidal, repellent and acaricidal activities. Acetylation of carvacrol is believed to enhance its nematicidal and acaricidal activities and to decrease its toxicity to hosts. Thus, the aim of this study was to evaluate the effect of different concentrations of acetylcarvacrol in the morphology of ovaries of engorged R. microplus ticks. The most remarkable morphological alterations found in the female germ cells were irregular and thicker chorion, decreasing in size and irregular shape of female germ cells (oocytes), cytoplasmatic vacuolization as well as ring-shaped nucleoli. These alterations were analyzed through a semi-quantitative method proposed in this study for ixodid ticks. Treatment group IV, which was exposed to 4.5 µL/mL of carvacrol acetate, showed the most significant alterations, and it was also statistically different when compared to control groups. Therefore, sublethal concentrations of acetylcarvacrol demonstrated to impact the reproductive system of R. microplus by causing several damages in the female germ cells. This would hinder the generation of new individuals, probably contributing for a long-term control of tick infestation.

[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.

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.

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.

Application of ethnobotanical repellents and acaricides in prevention, control and management of livestock ticks: A review.

Ticks transmit at least the same number or even more pathogens than any other group of blood-feeding arthropods worldwide affecting humans and animals. The eco-friendly control and management of tick vectors in a constantly changing environment is a crucial challenge. Besides the development of vaccines against ticks, IPM practices aimed at reducing tick interactions with livestock, emerging pheromone-based control tools, and few biological control agents, the extensive employment of acaricides and tick repellents still remain the most effective and ready-to-use strategies. However, the former is limited by the development of growing resistances as well as environmental concerns. Exploiting plants and plant products as sources of effective tick repellents and acaricides represents a promising strategy. In this scenario, the preservation of ethnobotanical information on repellent and acaricidal potential of plants is crucial. Here, we evaluated relevant information published in recent years, focused on plants used as repellents and acaricides against tick vectors in different regions worldwide. We selected a total of 238 plant species, which are traditionally used against ticks by native and local communities of Africa (Kenya, Uganda, Zimbabwe, South Africa), Europe (Serbia, Macedonia, Romania), Asia (Pakistan, India) and America (Brazil, Canada), from 56 families. However, only 7 families (i.e. Asteraceae, Euphorbiaceae, Fabaceae, Lamiaceae, Meliaceae, Apocynaceae and Solanaceae) represent the major quote (46%) of all plant species. We evaluated the differences in acaricidal and repellent efficacy of different formulations used. In the final section, implications arising from the surveyed anti-tick ethnobotanical knowledge and challenges for its future are discussed.

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.

Acaricidal activity of methanol extract of Acmella oleracea L. (Asteraceae) and spilanthol on Rhipicephalus microplus (Acari: Ixodidae) and Dermacentor nitens (Acari: Ixodidae).

We evaluated the acaricidal activity of Acmella oleracea methanol extract and spilanthol on Rhipicephalus microplus and Dermacentor nitens. The extract was made through maceration with methanol. From this extract, a dichloromethane fraction with 99% spilanthol was obtained and tested on R. microplus larvae and engorged females and D. nitens larvae. For evaluation against larvae, the modified larval packet test was used, and both the methanol extract and dichloromethane fraction were tested at concentrations of 0.2-50mg/mL. The modified larval packet test was also used in the lethal time (LT) test, with the methanol extract at a concentration of 12.5mg/mL and the percentage mortality was assessed after 15, 30, 45, 60, 75, 90, 120min and 24h. The 50% lethal time calculation (LT50) was performed in this test. The engorged female test was performed with R. microplus only, at concentrations of 25-200mg/mL for methanol extract and 2.5-20.0mg/mL for spilanthol. The methanol extract caused 100% mortality of the R. microplus and D. nitens larvae at concentrations of 3.1 and 12.5mg/mL, respectively. Spilanthol resulted in 100% mortality of R. microplus larvae at concentration of 1.6mg/mL and of D. nitens at 12.5mg/mL. In the lethal time assay using the methanol extract, the mortality rate was 100% for R. microplus and D. nitens larvae after 120min and 24h, with LT50 values of 38 and 57min, respectively. In the test of females, the egg mass weight and the hatching percentage of the groups treated with concentrations equal to or higher than 50.0mg/mL of methanol extract were significantly reduced (p<0.05), while for spilanthol, the reduction of the egg mass weight and hatching percentage occurred from concentrations of 10.0mg/mL and 2.5mg/mL, respectively. Females treated with 200.0mg/mL of extract died before starting oviposition, resulting in 100% effectiveness, while the best efficacy for spilanthol was 92.9% at a concentration of 20.0mg/mL. Thus we conclude that the methanol extract of A. oleracea and spilanthol have acaricidal activity against R. microplus and D. nitens.

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.

Chemo-profiling and bioassay of phytoextracts from Ageratum conyzoides for acaricidal properties against Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) infesting cattle and buffaloes in India.

In India, Rhipicephalus (Boophilus) microplus populations have developed a certain level of resistance to most of the acaricides marketed against tick species. To manage the problem, the present study was undertaken to evaluate the acaricidal potential of Ageratum conyzoides plants against acaricides-resistant ticks infesting cattle and buffaloes. The regression analysis of dose-response data of ethanolic extract of A. conyzoides revealed LC90 value of 8.91% against reference susceptible IVRI-1 line of R.(B.) microplus. The ethanolic extract was found efficacious against 76.7-90% acaricides-resistant field ticks and adversely affected oviposition showing 7.04-31.3% reduction in egg laying capacity. The extract was also showed an in vitro efficacy of 52.5 and 76.7% against reference resistant IVRI-4 and 5 lines. The GC/MS/MS profiling of hexane extract, two bioactive sub-fractions and essential oils revealed the presence of 6,7-dimethoxy-2,2-dimethyl-2H-1-benzopyran (precocene II) as a major phyto-compound. The bioactive sub-fractions showed 96.2-97.5% efficacy against larvae of IVRI-1 and 77.1-94.9% against multi-acaricide resistant larvae of IVRI-5 line of R.(B.) microplus. The results of this study provided significant support for the development of a phyto-formulation based on A. conyzoides species.

Ethnoveterinary plants and practices used for ecto-parasite control in semi-arid smallholder farming areas of Zimbabwe.

BACKGROUND: The inclusion of traditional plant-based ecto-parasite control methods in primary health care of livestock is increasingly becoming an important intervention for improving livestock productivity in resource-challenged smallholder farming areas. In this study, commonly used plants used for the control of cattle ticks and other pests were identified through a survey in four semi-arid districts of Zimbabwe. METHODS: A standard structured questionnaire with details of demographics, socioeconomic status of households, livestock parasites, control practices and list of ethnoveterinary plants used was used to interview 233 knowledgeable smallholder farmers in four districts. Focus group discussions with community members further provided insights on how the plants were being used and other issues surrounding ecto-parasite control and indigenous knowledge systems in the study areas. RESULTS: The older generation (>40 years) of the respondents were knowledgeable about ethnoveterinary plants and practices. Overall, 51 plant species were reportedly effective against cattle ticks and other livestock parasites. The most frequently mentioned plants were in descending order, Cissus quadrangularis (30.1%), Lippia javanica (19.6%), Psydrax livida (14.9%) and Aloe sp (14.9%). Most of the plant materials were prepared by crushing and soaking in water and spraying the extract on animals. Despite the knowledge of these useful pesticidal plants, the preferred animal health care for cattle and other highly ranked livestock species is still the use of commercial acaricides. Cattle dipping services were reported sporadic by 48% of the respondents. Traditional knowledge and plants are considered only as an alternative in the absence of conventional synthetic products. CONCLUSIONS: Livestock farming communities know of plant species used for livestock ecto-parasite control. The plant species are mostly used to complement commercial products. More work, is required to confirm the acaricidal properties claimed by the farmers in order to optimize and promote sustainable use of these plants.

Acaricidal activity of alkaloid fractions of Leucas indica Spreng against Rhipicephalus (Boophilus) annulatus tick.

The acaricidal activity from alkaloid and non-alkaloid fractions of Leucas indica were studied against Rhipicephalus (Boophilus) annulatus tick using adult immersion test under laboratory conditions. For this purpose, the engorged female R.(B.) annulatus tick were exposed to two fold serial dilutions of alkaloid extract (50 mg/ml, 25 mg/ml, 12.5 mg/ml, 6 mg/ml and 3 mg/ml) using 'dipping method' in vitro. The efficacy was assessed by measuring the percentage of adult mortality, inhibition of fecundity and hatching rate. The alkaloid fraction of the extract produced concentration dependent delayed adult tick mortality. The extract at a concentration of 50 mg/ml demonstrated 66.67 per cent mortality and 55.16 per cent inhibition of fecundity. Nicotine was identified as one of the compounds of alkaloid fraction. However, it did not reveal any acaricidal activity when tested in vitro at concentrations ranging from 62.5-1000 µg/mL. Hence, the acaricidal action of L. indica is not due to nicotine. Non alkaloid fraction also did not reveal any acaricidal effects against R. (B.) annulatus tick.

Evaluation acaricidal efficacy of botanical extract from Eupatorium adenophorum against the hard tick Haemaphysalis longicornis (Acari: Ixodidae).

The aim of this study was to evaluate the acaricidal activity of a botanical extract from Eupatorium adenophorum against the hard tick Haemaphysalis longicornis. This could result in developing effective extracts of E. adenophorum as a source of natural, low-toxicity plant-based acaricidal drugs. Adult engorged females of H. longicornis were collected from naturally infected goats. The engorged females were reared in the laboratory and their offspring (larvae and nymphs) were used as test ectoparasites. The toxic effects of botanical extracts from E. adenophorum against larvae and nymphs of H. longicornis were evaluated. The results showed that the extracts with 1.5 and 1.0g/ml (w/v) concentrations were toxic for H. longicornis, comparable to a toxic effect of 2% chlorpyrifos (positive control). The median lethal time (LT50) for larval and nymphal ticks with 1.5g/ml (w/v) concentration of extract were 0.790 (LT99=1.065) and 1.018 (LT99=10.608) hours, respectively, whereas the LT50 of 1.0g/ml (w/v) concentration were 1.445 (LT99=6.047) and 1.313 (LT99=29.932) hours for larval and nymphal ticks, respectively. At a concentration of 1.5g/ml (w/v), an acaricidal effect of 100% was achieved for both larval and nymphal ticks, while a concentration of 1.0g/ml (w/v) resulted in 100% (for larvae) and 93% (for nymphs) within a 6h period. In additional, we found that the relatively low concentration (0.5g/ml) also obtained a good acaricidal effect during the short experimental period, with 2.22 and 2.651h LT50 for larval and nymphal ticks, respectively. These results indicate that E. adenophorum contains potent acaricidal ingredients against the hard tick H. longicornis.

Acaricidal activity of Lippia gracilis essential oil and its major constituents on the tick Rhipicephalus (Boophilus) microplus.

The present study aimed to evaluate the activity of Lippia gracilis Schauer essential oil obtained from different L. gracilis genotypes and their major components, carvacrol and thymol against Rhipicephalus (Boophilus) microplus (cattle tick) larvae and engorged females. The larval test was performed parallel to the adult immersion test for engorged females for four L. gracilis genotypes. Similar tests were further performed for their major compounds carvacrol and thymol. Carvacrol (LC50 of 0.22 and 4.46 mg/mL, to larvae and engorged females, respectively) was more efficient than thymol (LC50 of 3.86 and 5.50 mg/mL, to larvae and engorged females, respectively). The lethal concentrations obtained for the isolated essential oil from genotypes LGRA-201 against larvae (1.31 mg/mL) and LGRA-106 against engorged females (4.66 mg/mL) confirmed the acaricidal activity of L. gracilis essential oil and its effectiveness in controlling the southern cattle tick.

Chemical composition and efficacy of dichloromethane extract of Croton sphaerogynus Baill. (Euphorbiaceae) against the cattle tick Rhipicephalus microplus (Acari: Ixodidae).

The cattle tick Rhipicephalus microplus is widely distributed in tropical and subtropical regions, causing high economic impact on cattle production. The control of tick infestations is regarded worldwide as critical and has been based on the use of organophosphates, synthetic pyretroids, amitraz and recently ivermectin and fipronil. The present study reports the analysis by gas chromatography/mass spectrometry of the constituents of leaf extracts of Croton sphaerogynus and results of acaricidal activity against the cattle tick R. microplus. The larval package test using the serial dilutions 0.625%, 1.25%, 2.5%, 5.0%, 10.0% and 20.0% (v/v) gave mortality rates 2.25%, 8.26%, 8.81%, 24.80%, 83.66% and 99.32%, respectively. Relevant constituents identified were abietanes, podocarpenes and clerodane type furano diterpenes. The present work may represent a possibility of attainment of natural substances useful for the control of R. microplus.