Acaricidal activity of extracts from Petiveria alliacea (Phytolaccaceae) against the cattle tick, Rhipicephalus (Boophilus) microplus (Acari: ixodidae)

Current perspectives and difficulties in the design of acaricides and repellents from plant-derived compounds for tick control

Ticks and tick-borne diseases have gained increasing attention in recent years due to their impact on public health and significant losses in livestock production. The use of synthetic compounds for tick control is becoming problematic, mainly due to the resistance to commercially available products as well as their toxicity. Therefore, new alternative control methods are required. For this purpose, plant-derived extracts may be considered as effective repellents and/or acaricides. The present literature review focuses on studies evaluating the acaricidal and repellent activity of plant-derived extracts and plant secondary metabolites. We also noted recent advances in protein-ligand-docking simulation to examine the possible toxic effect of natural chemical compounds on ticks. In conclusion, plant-derived repellents/acaricides can be effective against ticks, especially in rural areas and livestock farms.

Evaluation of synergism in essential oils against the cattle tick Rhipicephalus microplus in Burkina Faso

The cattle tick Rhipicephalus microplus affects animal production economically by reducing weight gain and milk production and causing diseases, such as babesiosis and anaplasmosis. Using synthetic acaricides to reduce their incidence has caused the emergence of resistant tick populations. The present study aimed to assess the in vitro acaricidal activity of combinations of essential oils (EOs) from Ocimum americanum, Ocimum gratissimum, and Lippia multiflora against R. microplus larvae. In fact, numerous biological properties have been reported on EOs from these three plants, including acaricidal properties. Hence, a larval immersion test was performed using a population of R. microplus resistant to synthetic acaricides used in Burkina Faso. Results revealed that EO from O. gratissimum was the most effective on R. microplus larvae with LC50 and LC90 values at 10.36 and 15.51 mg/mL, respectively. For EO combinations, the most significant synergistic effect was obtained by combination 6 (1/3 O. americanum + 2/3 O. gratissimum +1/6 L. multiflora), with a combination index value of 0.44. All combinations presented dose reduction index >1, indicating a favorable dose reduction. According to the literature, this is the first study to determine the combination effect of EOs from the abovementioned plants in controlling R. microplus activity in vitro. Thus, the combination of these EOs is an alternative to control the resistant populations of invasive cattle ticks.

Acaricidal efficacy evaluation of amitraz and diazinon against Amblyomma variegatum tick species in Waghimra zone, northern Ethiopia

Ticks pose a substantial economic burden associated with production loss and treatment costs globally. Ethiopia has tremendous livestock resources, but its productivity is hindered by various animal health challenges in which ticks are the top priority, with a limited response to acaricidal treatments. Hence, we designed an acaricidal efficacy trial for the top commercially available Chemicals (amitraz and diazinon) to examine their efficacy against the widely distributed tick species (Amblyoma variegatum). Ticks were collected from animals admitted to veterinary clinics with no history of treatment with acaricides. Adult Immersion Technique (AIT) was employed to detect acaricidal resistance, and the mean percent control and antiparasitic efficacy were used to estimate tick susceptibility with a completely randomized laboratory-based trial (CRT). The mean weights of eggs laid by ticks subjected to amitraz and diazinon indicated that amitraz had a better egg-laying-inhibition effect than diazinon. The mean control percentages of amitraz and diazinon were 92.8 ± 5.6% and 69.7 ± 3.1%, respectively, with a highly significant difference (P-value = 0.00). The antiparasitic efficacy of the two drugs was 57.5 ± 0.96 and 37.5% ± 0.96 for amitraz and diazinon, respectively, which revealed that amitraz was statistically better than diazinon in killing adult ticks (P-value =0.026). In general, ticks treated with diazinon showed evidence of resistance development, and amitraz is relatively the most effective acaricide; we recommend its use in the study area and other locations with similar settings.

Ethanolic Extracts of Datura innoxia Have Promising Acaricidal Activity against Rhipicephalus microplus as It Blocks the Glutathione S-Transferase Activity of the Target Tick

Rhipicephalus microplus is a major bovine ectoparasite that negatively impacts the cattle industry. The acaricidal activity of Datura innoxia ethanolic plant extract against R. microplus, compared with trichlorfon, was examined using the adult immersion test (AIT), and larval packet test (LPT). In vitro acaricidal activity of the selected plant extract against R. microplus engorged females was evaluated at different concentrations (2.5, 5, 10, 20, and 40 mg/mL), and was the same for AIT and LPT. It was further supported by in silico molecular docking of D. innoxia's 21 phytochemicals against the R. microplus Glutathione S-transferases (RmGST) protein's three-dimensional (3D) structure predicted by the trRosetta server. The modeled 3D structure was then evaluated and confirmed with PROCHECK, ERRAT, and Verify3D online servers. To predict the binding mechanisms of these compounds, molecular docking was performed using Auto dock Vina software, and molecular dynamic (MD) simulations were used to investigate the protein atom's dynamic motion. D. innoxia has a relatively higher inhibitory effect on oviposition (from 9.81% to 45.37%) and total larval mortality (42.33% at 24 h and 93.67% at 48 h) at 40 mg/mL. Moreover, the docking results showed that the chemicals norapoatropine and 7-Hydroxyhyoscyamine have strong interactions with active site residues of the target protein, with a docking score of -7.3 and -7.0 Kcal/mol, respectively. The current work also provided a computational basis for the inhibitors of Glutathione S-transferases that were studied in this research work, and this new knowledge should aid in creating new and effective acaricidal chemicals. Furthermore, this plant extract's acaricide activity and its effect on oviposition and larval mortality were established in this work for the first time, indicating the possible use of this extract in the management of ticks.

Acaricidal and anthelmintic efficacy of Ocimum basilicum essential oil and its major constituents estragole and linalool, with insights on acetylcholinesterase inhibition

The present study evaluated the acaricidal and anthelmintic action of Ocimum basilicum essential oil and its main components against ticks and helminth parasites as well as to relate these activities to acetylcholinesterase inhibition. The in vitro acaricidal activity against Hyalomma scupense was evaluated by Adult Immersion Test (AIT) and Larval Packet Test (LPT), while the in vivo nematocidal potential was assessed in laboratory mice infected with Heligmosomoides polygyrus using fecal egg count reduction (FECR) and total worm count reduction (TWCR). Chemical analyzes were performed by gas chromatography coupled to mass spectrometry (GC-MS). Estragole (80.87%) and linalool (16.12%) were the major compounds detected in O. basilicum essential oil. In the AIT assay for H. scupense tick, LC₅₀ of estragole, O. basilicum oil and linalool were 0.73, 0.81 and 0.97 mg/mL, respectively. In LPT, estragole, linalool and essential oil showed LC₅₀ of 0.22, 1.11 and 1.19 mg/mL, respectively. Against He. polygyrus, the highest activity was observed with estragole administered at 100 mg/kg body weight (bwt), which resulted in a FECR of 90.86% and a TWCR of 82.91%. The O. basilicum essential oil, estragole and linalool inhibited the enzyme acetylcholinesterase (AChE) extracted from both parasites species. Estragole was found the most active AChE inhibitor with IC₅₀ of 0.176 mg/mL for H. scupense and IC₅₀ of 0.138 mg/mL for He. polygyrus larvae. The results of the present study pointed out the importance of the traditional use of O. basilicum as an eco-friendly alternative against endo and ectoparasites. In vivo trials should also be conducted to confirm the above-mentioned activities and to assure the safe use of natural plants.

Integrative Alternative Tactics for Ixodid Control

Simple Summary

Hard ticks are important for economic and health reasons, and control has mainly relied upon use of synthetic acaricides. Contemporary development of resistance and concerns relating to health and environmental safety have elicited exploration into alternative tactics for hard tick management. Some examples of alternative tactics involve biological control, desiccant dusts, growth regulators, vaccines, cultural methods, and ingested medications.

Abstract

Ixodids (hard ticks), ectoparasitic arthropods that vector the causal agents of many serious diseases of humans, domestic animals, and wildlife, have become increasingly difficult to control because of the development of resistance against commonly applied synthetic chemical-based acaricides. Resistance has prompted searches for alternative, nonconventional control tactics that can be used as part of integrated ixodid management strategies and for mitigating resistance to conventional acaricides. The quest for alternative control tactics has involved research on various techniques, each influenced by many factors, that have achieved different degrees of success. Alternative approaches include cultural practices, ingested and injected medications, biological control, animal- and plant-based substances, growth regulators, and inert desiccant dusts. Research on biological control of ixodids has mainly focused on predators, parasitoid wasps, infective nematodes, and pathogenic bacteria and fungi. Studies on animal-based substances have been relatively limited, but research on botanicals has been extensive, including whole plant, extract, and essential oil effects on ixodid mortality, behavior, and reproduction. The inert dusts kaolin, silica gel, perlite, and diatomaceous earth are lethal to ixodids, and they are impervious to environmental degradation, unlike chemical-based toxins, remaining effective until physically removed.

Acaricidal Efficacy of Plants from Ecuador, Ambrosia peruviana (Asteraceae) and Lepechinia mutica (Lamiaceae) against Larvae and Engorged Adult Females of the Common Cattle Tick, Rhipicephalus microplus

Control measures against common cattle tick Rhipicephalus microplus are of the upmost importance because of considerable, deleterious impact on a farm’s economy. Due to resistance phenomena to synthetic acaricides being a constraint in affected farms, the search for plant derivatives as acaricides has increased dramatically in recent years. In this work, essential oils obtained from two Ecuadorian plants, Ambrosia peruviana and Lepechinia mutica (EO_Ap, EO_Lm), traditionally used as insecticides in indigenous communities, were studied on larvae and engorged females at the parasitic stages of R. microplus. Larvae and females were treated with five (0.0625, 0.125, 0.25, 0.50 and 1%) and six concentrations (0.125, 0.25, 0.50, 1, 2 and 4%), respectively, of each EOs_Ap/Lm. A 98–99% larval mortality was achieved with 0.5% of both EOs_Ap/Lm. EO_Ap inhibited oviposition and egg hatching up to 82% and 80%, respectively, and had an overall efficacy of 93.12%. Efficacy of EO_Lm was 72.84%, due to the low influence of EO_Lm on reproductive parameters. By steam distillation and GC-MS analysis, γ-Curcumene was identified as the main constituent (52.02%) in the EO_Ap and Shyobunol (10.80%) in EO_Lm. The results suggest that major components of both essential oils should be further studied as promissory acaricides against R. microplus.

Acaricidal and Repellent Effects of Essential Oils against Ticks: A Review

Tick control is a priority in order to prevent the transmission of vector-borne diseases. Industrial chemical acaricides and repellents have been the most efficient tools against hard ticks for a long time. However, the appearance of resistances has meant the declining effectiveness of the chemicals available on the market. The trend today is to develop alternative control methods using natural products to replace nonefficient pesticides and to preserve the efficient ones, hoping to delay resistance development. Traditional in vitro evaluation of acaricidal activity or resistance to synthetic pesticides have been reviewed and they mainly focus on just one species, the one host tick (Rhipicephalus (Boophilus) microplus (Acari: Ixodidae)). Recent reports have called for the standardization of natural product components, extraction techniques, and experimental design to fully discover their acaricidal potential. This study reviews the main variables used in the bibliography about the efficiency of natural products against ticks, and it proposes a unification of variables relating to ticks, practical development of bioassays, and estimation of ixodicidal activity.

Rhipicephalus Tick: A Contextual Review for Southeast Asia

Rhipicephalus species are distributed globally with a notifiable presence in Southeast Asia (SEA) within animal and human populations. The Rhipicephalus species are highly adaptive and have established successful coexistence within human dwellings and are known to be active all year round, predominantly in tropical and subtropical climates existing in SEA. In this review, the morphological characteristics, epidemiology, and epizootiology of Rhipicephalus tick species found in SEA are reviewed. There are six commonly reported Rhipicephalus ticks in the SEA region. Their interactions with their host species that range from cattle, sheep, and goats, through cats and dogs, to rodents and man are discussed in this article. Rhipicephalus-borne pathogens, including Anaplasma species, Ehrlichia species, Babesia species, and Theileria species, have been highlighted as are relevant to the region in review. Pathogens transmitted from Rhipicepahalus ticks to host animals are usually presented clinically with signs of anemia, jaundice, and other signs of hemolytic changes. Rhipicephalus ticks infestation also account for ectoparasitic nuisance in man and animals. These issues are discussed with specific interest to the SEA countries highlighting peculiarities of the region in the epidemiology of Rhipicephalus species and attendant pathogens therein. This paper also discusses the current general control strategies for ticks in SEA proffering measures required for increased documentation. The potential risks associated with rampant and improper acaricide use are highlighted. Furthermore, such practices lead to acaricide resistance among Rhipicephalus species are highlighted.

Cytotoxic effects of Satureja montana L. essential oil on oocytes of engorged Rhipicephalus microplus female ticks (Acari: Ixodidae)

In addition to pesticidal activity, the capacity of natural compounds to inhibit the reproduction of parasites emerge as an important alternative tick control method. In this context, Satureja spp. stand out due to their recognized pesticidal properties. Among parasites of veterinary importance, the cattle tick, Rhipicephalus microplus, is responsible for great economic losses in livestock and transmission of relevant pathogens. Thus, the aim of this study was to evaluate the effects of different concentrations of the essential oil of Satureja montana L. on the ovary morphology of R. microplus engorged females through histological and histochemical techniques. The most remarkable morphological changes found were: cytoplasmic vacuolation of germ cells, irregular and thicker chorion, irregular oocyte shape, ring-shaped nucleolus, decrease in protein and carbohydrate content in oocytes, in addition to cellular changes in the oviduct and pedicel. All morphological changes were assessed using a semiquantitative method already established in the literature. Ticks exposed to 5.0 μl/ml of essential oil showed the most significant changes when compared to control groups. Thus, the essential oil of S. montana L. damaged the reproductive system of R. microplus, which may impair ticks' offspring production and promote a long-term control of this species. HIGHLIGHTS: The essential oil of Satureja montana L. affects the ovary morphology of the cattle tick. The main morphological alterations found were cytoplasmic vacuolation, irregular and thicker chorion and irregular oocyte shape. These alterations may impair the development of eggs.

Anthelmintic Activity of Extracts and Active Compounds From Diospyros anisandra on Ancylostoma caninum, Haemonchus placei and Cyathostomins

The present study aimed to evaluate the anthelmintic activity of leaf and bark extracts of Diospyros anisandra collected during different seasons and their major constituents on eggs of Ancylostoma caninum, Haemonchus placei, and cyathostomins. Specifically, the eclosion inhibition of the methanolic extracts of the leaves and bark of D. anisandra collected during the dry and rainy seasons (600–37.5 μg/ml) were evaluated in addition to the fractions, sub-fractions (300–37.5 μg/ml) and active major constituents (150–2.3 μg/ml). The rainy season bark extract had the highest percentage of eclosion inhibition (PEI) against the evaluated nematodes (≥ 90% at 75 μg/ml) along with high ovicidal activity (90.0 to 93.4% at 75 μg/ml). The purification of the rainy season bark extract showed that its biological activity came from the non-polar n-hexane fraction (≥ 93% at 75 μg/ml). The bioguided fractionation pointed to sub-fraction 5 as having the highest anthelmintic activity against the three evaluated genera of nematodes (PEI ≥ 93% at 37.5 μg/ml). Gas chromatography and mass spectrometry revealed that the major constituent in sub-fraction 5 was plumbagin. Upon evaluation, plumbagin was confirmed to be responsible for the anthelmintic activity of D. anisandra, with a PEI ≥ 90% at 2.3 μg/ml on the three evaluated nematodes. Additionally, the compounds betulin and lupeol in the bark of D. anisandra were evaluated but presented low anthelmintic activity (PEI ≤ 5.3% at 2.3 μg/ml). In conclusion, the rainy season bark extract of D. anisandra exerts a high ovicidal activity against the eggs of the three studied nematodes. Plumbagin is the active compound responsible for this activity and represents a potential alternative for the control of different genera of gastrointestinal nematodes given the current scenario of anthelmintic resistance.

Effects of the essential oil from Cymbopogon citratus on mortality and morphology of the tick Haemaphysalis longicornis (Acari: Ixodidae)

Haemaphysalis longicornis is one of the most prevalent tick species across eastern Asia, Australia, and New Zealand, and has been implicated as a vector of several pathogenic agents. This study evaluated the in vitro acaricidal efficacy of Cymbopogon citratus (lemongrass) essential oil on unfed H. longicornis using the adult and nymph immersion test, and the larval packet test. Six concentrations with three replications each of 10, 20, 30, 40, 50 and 60 mg/mL (adults and nymphs) were used, and 2.5, 5, 10, 20, 40 and 80 mg/mL (larvae), with control group (50% ethanol). The adult and nymph mortality rates were 98 and 100% at 50 mg/mL, and 95 and 100% at 60 mg/mL, respectively, whereas the larval mortality rate was 94 and 96% at 40 and 80 mg/mL, respectively. Mortality of adult, nymph and larva increased significantly in a dose-dependent manner. The LC₅₀ for adult, nymph, and larva, were 29.21 (95% confidence interval 25.90-32.58), 28.18 (23.78-32.25), and 28.06 (25.57-30.90) mg/mL, respectively. Scanning electron microscopy and light microscopy revealed a disjointed sensilla base from the sockets, cuticular cracks, blocked aeropyles, and shrinking of the midgut. These results showed that C. citratus essential oil could be a good eco-friendly alternative control strategy against ectoparasites like ticks due to its high acaricidal efficacy.

Effects of different extracts of three Annona species on egg-hatching processes of Haemonchus contortus

This study assessed the in vitro anthelmintic (AH) activity of methanol and acetone:water leaf extracts from Annona squamosa, A. muricata and A. reticulata against Haemonchus contortus eggs. The egg hatch test was used to determine the effective concentrations required to inhibit 50% of eggs hatching (EC50). The role of polyphenols on AH activity was measured through bioassays with and without polyvinylpolypyrrolidone (PVPP). Methanolic extracts mainly caused the death of eggs at the morula stage (ovicidal activity). Meanwhile, acetone:water extracts caused egg-hatching failure of developed larvae (larvae failing eclosion (LFE) activity). The lowest EC50 values against H. contortus eggs were observed for the methanolic extracts from A. reticulata and A. muricata (274.2 and 382.9 µg/ml, respectively). From the six extracts evaluated, the methanolic extracts of A. muricata, A. reticulata and A. squamosa showed the highest ovicidal activity, resulting in 98.9%, 92.8% and 95.1% egg mortality, respectively. When the methanolic extract of A. squamosa was incubated with PVPP, its AH activity increased. Similarly, when acetone:water extracts of A. muriata and A. reticulata were incubated with PVPP, their LFE activity increased. Alkaloids were only evident in methanolic extracts, irrespective of PVPP incubation. The presence of acetogenins was not observed. In conclusion, methanolic extracts obtained from leaves of A. muricata, A. reticulata and A. squamosa showed ovicidal activity affecting the morula of H. contortus eggs, with minor LFE activity. Meanwhile, acetone:water extracts showed mostly LFE activity, with a lower proportion of ovicidal activity.

Efecto bioplaguicida de extractos vegetales para el control de Spodoptera frugiperda en el cultivo de maíz (Zea mays)

El maíz es el segundo cereal de mayor producción en Colombia con un 21,9 % de la superficie total. La plaga Spodoptera frugiperda ataca la planta desde las primeras semanas de crecimiento, devorando sus hojas, tallo y granos; disminuyendo el rendimiento de los cultivos. Esta plaga se controla con el uso indiscriminado de plaguicidas sintéticos como: carbofurano, clorpirifos y atrazina. En esta investigación, los extractos de Azadirachta indica, Piper nigrum, Petiveria alliacea y sus mezclas; y los extractos de Nicotiana tabacum, Lippia alba, Allium sativum y sus mezclas se aplicaron como bioplaguicidas en plantas de maíz amarillo tradicional. Después de la tercera semana de crecimiento, los tratamientos se aplicaron dos veces al día cada tres días durante siete semanas. Las variables estudiadas fueron número de larvas muertas, altura de las plantas y daño en hojas y tallos. Las plantas tratadas crecieron dos veces más y su grado de afectación, según la escala de Mihm, fue menor que las plantas del grupo testigo. Los porcentajes de eficacia de las seis especies vegetales y sus mezclas fueron representativos (>80 %), de acuerdo con Henderson y Tilton, demostrando que estos extractos vegetales son una alternativa viable para el control de S. frugiperda.

In vitro efficacy of essential oils with different concentrations of 1,8-cineole against Rhipicephalus (Boophilus) microplus

Abstract The aim of this study was to evaluate the acaricidal activity of essential oils from three species of plants with intermediary concentrations of 1,8-cineole against the tick species Rhipicephalus (Boophilus) microplus. For this purpose, five serial concentrations (100.0, 50.0, 25.0, 12.5, 6.2 mg/mL) of essential oils from Mesosphaerum suaveolens (L.) Kuntze, Ocimum gratissimum L. and Alpinia zerumbet (Pers.) B. L. Burtt & R. M. Sm. were used on larval packet and adult immersion tests. The essential oils were analysed by gas chromatography-mass spectrometry (GC/MS) and gas chromatography-flame ionization detection (GC-FID), being detected 35.8, 24.7 and 24.0% of 1.8-cineol in the oils of M. suaveolens, O. gratissimum and A. zerumbet, respectively. The lethal concentration (LC 50) of each oil for larvae and engorged females was calculated through Probit analysis. All essential oils showed high efficacy (≥ 95.0%) on engorged females at the 100.0 mg/mL concentration. In regards to larvae, O. gratissimum (LC 50 = 11.9 mg/mL) was the most potent, followed by the A. zerumbet (LC50 = 19.7 mg/mL) and the M. suaveolens (LC50 = 51.6 mg/mL) essential oils. These results show that other compounds interfere with 1,8-cineole action.

In vitro activity of the hydroalcoholic extract of Chenopodium ambrosioides against engorged females of Rhipicephalus (Boophilus) microplus

ABSTRACT: Rhipicephalus (Boophilus) microplus, known as the cattle tick, is a cause of great economic losses for dairy cattle farming because of its high frequency of occurrence and the difficulty in controlling it. The aim of this study was to evaluate the in vitro activity of Chenopodium ambrosioides extract on R. (B.) microplus. For this purpose, 125 females were selected and classified into five groups according to their weight, in order to ensure that the females used presented homogeneous weight. The treatments comprised 40 and 60% extracts of Chenopodium ambrosioides, distilled water, ethanol (70ºGL) and 12.5% amitraz. The extracts of C. ambrosioides (40 and 60%) showed effectiveness of 99.7 and 100% and higher percentages of dead females than the other treatments: 64 and 96%, respectively (p<0.001). In the groups exposed to distilled water and ethanol (70º GL), 92 and 88% of the females maintained oviposition. In the females exposed to 40 and 60% extracts, oviposition of 36 and 4% occurred, respectively. It was concluded that the extract of Chenopodium ambrosioides, at both concentration evaluated, had high efficiency against engorged females of cattle ticks.

Strategies for the control of Rhipicephalus microplus ticks in a world of conventional acaricide and macrocyclic lactone resistance

Infestations with the cattle tick, Rhipicephalus microplus, constitute the most important ectoparasite problem for cattle production in tropical and subtropical regions worldwide, resulting in major economic losses. The control of R. microplus is mostly based on the use of conventional acaricides and macrocyclic lactones. However, the intensive use of such compounds has resulted in tick populations that exhibit resistance to all major acaricide chemical classes. Consequently, there is a need for the development of alternative approaches, possibly including the use of animal husbandry practices, synergized pesticides, rotation of acaricides, pesticide mixture formulations, manual removal of ticks, selection for host resistance, nutritional management, release of sterile male hybrids, environmental management, plant species that are unfavourable to ticks, pasture management, plant extracts, essential oils and vaccination. Integrated tick management consists of the systematic combination of at least two control technologies aiming to reduce selection pressure in favour of acaricide-resistant individuals, while maintaining adequate levels of animal production. The purpose of this paper is to present a current review on conventional acaricide and macrocyclic lactone resistance for better understanding and control of resistant ticks with particular emphasis on R. microplus on cattle.

Southeast Asian Medicinal Plants as a Potential Source of Antituberculosis Agent

Despite all of the control strategies, tuberculosis (TB) is still a major cause of death globally and one-third of the world's population is infected with TB. The drugs used for TB treatment have drawbacks of causing adverse side effects and emergence of resistance strains. Plant-derived medicines have since been used in traditional medical system for the treatment of numerous ailments worldwide. There were nine major review publications on antimycobacteria from plants in the last 17 years. However, none is focused on Southeast Asian medicinal plants. Hence, this review is aimed at highlighting the medicinal plants of Southeast Asian origin evaluated for anti-TB. This review is based on literatures published in various electronic database. A total of 132 plants species representing 45 families and 107 genera were reviewed; 27 species representing 20.5% exhibited most significant in vitro anti-TB activity (crude extracts and/or bioactive compounds 0–<10 µg/ml). The findings may motivate various scientists to undertake the project that may result in the development of crude extract that will be consumed as complementary or alternative TB drug or as potential bioactive compounds for the development of novel anti-TB drug.

Acaricidal activity of Havardia albicans and Caesalpinia gaumeri methanolic leaf extracts on Rhipicephalus microplus and its toxicity to laboratory animals

The acaricidal activity of methanolic extracts from the leaves of Havardia albicans (Kunth Britton and Rose) and Caesalpinia gaumeri (Greenm) were tested on the larvae and adults of the cattle tick Rhipicephalus microplus Canestrini using the larval immersion test and the adult immersion test, respectively. The toxicity of these extracts was also evaluated on laboratory animals using toxicity bioassays at different concentrations: skin irritability (500 mg/ml), acute oral toxicity (5000 mg/kg), ocular irritability (1000 mg/ml) and dermal toxicity (5000 mg/kg). The acaricidal activity of the H. albicans extracts on R. microplus larvae showed a LC₅₀ of 7.0% (4.3-11.4) and a LC₉₉ of 25.5% (14.26-201.5). The acaricidal activity of the C. gaumeri extracts on larvae showed a LC₅₀ of 7.8% (5.74-10.65) and a LC₉₉ of 38.32% (22.22-146.48). The H. albicans extracts showed moderate acaricidal activity in the inhibition of egg laying (54.4 ± 12.4) and the inhibition of larval hatching (48.7 ± 6.8) in R. microplus adults. The C. gaumeri extracts also showed moderate acaricidal activity in the inhibition of egg laying (51.0 ± 11.2). However, none of the evaluated extracts showed significant toxicity on laboratory rodents. These plants show the potential to control R. microplus and could be administered topically or orally in animals. Further studies are needed to identify the active compound(s) and to evaluate the effects of these plants on R. microplus in vivo.

Plant products and secondary metabolites with acaricide activity against ticks

The present review documents the results of studies evaluating the acaricidal activity of different plant products and secondary metabolites against ticks that are resistant and susceptible to conventional acaricides. Studies published from 1998 to 2016 were included. The acaricidal activity of plant extracts, essential oils and secondary compounds from plants have been evaluated using bioassays with ticks in the larval and adult stages. There is variable effectiveness according to the species of plant and the concentrations used, with observed mortalities ranging from 5 to 100% against the Rhipicephalus (Boophilus), Amblyomma, Dermacentor, Hyalomma, and Argas genera. A number of plants have been reported to cause high mortalities and/or affect the reproductive capacity of ticks in the adult phase. In the majority of these trials, the main species of plants evaluated correspond to the families Lamiaceae, Fabaceae, Asteraceae, Piperaceae, Verbenaceae, and Poaceae. Different secondary metabolites such as thymol, carvacrol, 1,8-cineol and n-hexanal, have been found to be primarily responsible for the acaricidal activity of different essential oils against different species of ticks, while nicotine, dibenzyldisulfide and dibenzyltrisulfide have been evaluated for plant extracts. Only thymol, carvacrol and 1,8-cineol have been evaluated for acaricidal activity under in vivo conditions. The information in the present review allows the conclusion that the secondary metabolites contained in plant products could be used as an alternative for the control of ticks that are susceptible or resistant to commercial acaricides.

Synergistic action of fatty acids, sulphides and stilbene against acaricide-resistant Rhipicephalus microplus ticks

Six compounds in a methanolic extract of Petiveria alliacea stem (cis-stilbene; benzyl disulphide; benzyl trisulphide; and methyl esters of hexadecanoic acid, octadecadienoic acid and octadecenoic acid) are known to exercise acaricide activity against cattle tick Rhipicephalus microplus larvae and adults. The synergistic effect of 57 combinations of these six compounds on acaricide activity against R. microplus was evaluated. Larvae immersion tests produced the lethal concentrations needed to kill 50% (LC₅₀) and 99% (LC₉₉) of the population. Adult immersion tests produced rates (%) for mortality, oviposition inhibition and eclosion inhibition. Individually, none of the compounds (1% concentration) exhibited acaricide activity (mortality ≤2.3%). When combined, however, nine mixtures exhibited a synergistic increase in activity, with high mortality rates (≥92%) in larvae. Values for LC₅₀ ranged from 0.07 to 0.51% and those for LC₉₉ from 0.66 to 5.16%. Thirty six compound mixtures had no significant activity (mortality ≤30%) against larvae. Two mixtures exhibited synergism against adults, with high rates (≥92%) of oviposition inhibition. The mixtures based on the benzyl disulphide+benzyl trisulphide pairing produced a synergistic effect against acaricide-resistant R. microplus larva and adults, and are therefore the most promising combination for controlling this ubiquitous ectoparasite.

Tick repellents and acaricides of botanical origin: a green roadmap to control tick-borne diseases?

Arthropods are dangerous vectors of agents of deadly diseases, which may hit as epidemics or pandemics in the increasing world population of humans and animals. Among them, ticks transmit more pathogen species than any other group of blood-feeding arthropods worldwide. Thus, the effective and eco-friendly control of tick vectors in a constantly changing environment is a crucial challenge. A number of novel routes have been attempted to prevent and control tick-borne diseases, including the development of (i) vaccines against viruses vectored by ticks; (ii) pheromone-based control tools, with special reference to the "lure and kill" techniques; (iii) biological control programmes relying on ticks' natural enemies and pathogens; and (iv) the integrated pest management practices aimed at reducing tick interactions with livestock. However, the extensive employment of acaricides and tick repellents still remains the two most effective and ready-to-use strategies. Unfortunately, the first one is limited by the rapid development of resistance in ticks, as well as by serious environmental concerns. On the other hand, the exploitation of plants as sources of effective tick repellents is often promising. Here, we reviewed current knowledge concerning the effectiveness of plant extracts as acaricides or repellents against tick vectors of public health importance, with special reference to Ixodes ricinus, Ixodes persulcatus, Amblyomma cajennense, Haemaphysalis bispinosa, Haemaphysalis longicornis, Hyalomma anatolicum, Hyalomma marginatum rufipes, Rhipicephalus appendiculatus, Rhipicephalus (Boophilus) microplus, Rhipicephalus pulchellus, Rhipicephalus sanguineus and Rhipicephalus turanicus. Eighty-three plant species from 35 botanical families were selected. The most frequent botanical families exploited as sources of acaricides and repellents against ticks were Asteraceae (15 % of the selected studies), Fabaceae (9 %), Lamiaceae (10 %), Meliaceae (5 %), Solanaceae (6 %) and Verbenaceae (5 %). Regression equation analyses showed that the literature grew by approximately 20 % per year (period: 2005-2015). Lastly, in the final section, insights for future research are discussed. We focused on some caveats for future data collection and analysis. Current critical points mainly deal with (a) not uniform methods used, which prevent proper comparison of the results; (b) inaccurate tested concentrations, frequently 100 % concentration corresponded to the gross extract, where the exact amounts of extracted substances are unknown; and (c) not homogeneous size of tested tick instars and species. Overall, the knowledge summarized in this review may be helpful for comparative screening among extensive numbers of plant-borne preparations, in order to develop newer and safer tick control tools.

Comparative in vitro anti-tick efficacy of commercially available products and newly developed phyto-formulations against field collected and resistant tick lines of Rhipicephalus (Boophilus) microplus

Rhipicephalus (Boophilus) microplus is considered as one of the most widely distributed tick species ecto-parasitizing on livestock and causes fatal diseases with significant production loss. To address the problem of controlling acaricide resistant tick infestations on animals, attention has been paid to develop eco-friendly phyto-acaricides. The present study was undertaken to evaluate the comparative anti-tick activities of commercially available herbal and chemical products with chemically characterized phyto-formulations developed recently against field ticks and resistant tick lines of R. (B.) microplus. The chemical product Butox^® Vet was found nearly passive against all the tested resistant tick lines. However, one of the commercial polyherbal product, Zerokeet^® showed an efficacy (E%) of 41.8-75.4 % ([Formula: see text]) using recommended dilution (1:2) against field ticks and resistant tick lines. However, the other commercial product, Erina^® EP has very limited efficacy against all the tested tick. In comparison, the newly developed phyto-formulation, NBA/13/B/2 and NAC-01 conferred an E% of 82.4-91.3 % ([Formula: see text]) and 62.3-94.6 % ([Formula: see text]), respectively, against tested resistant ticks. Results indicated higher marketing potentiality of newly developed formulation in the existing tick problem scenario.

Petiveria alliacea exerts mnemonic and learning effects on rats

ETHNOPHARMACOLOGICAL RELEVANCE

Petiveria alliacea L. (Phytolaccaceae) is a perennial shrub native to the Amazon region and other tropical areas such as Central America and the Caribbean. Popularly known as mucuracaá, P. alliacea is used in the folk medicine for a broad variety of therapeutic purpose and also in religious ceremonies by slaves as a sedative, which highlights its properties on the Central Nervous System (CNS).

AIM OF THE STUDY

The present study evaluated the effects of the P. alliacea leaves hydroalcoholic extract (PaLHE) on the cognition, including learning and memory.

MATERIAL AND METHODS

Three-month-old male and female Wistar rats (n=8-10/group) were administered with 900mg/kg of PaLHE. The behavioral assays included Step-down Inhibitory avoidance (IA) and Morris Water Maze (MWM) tests.

RESULTS

Consistent with our previous reports, P. alliacea improved long-term memory. It also exerted previously unreported effects on short-term and spatial memory improvement, and increased learning in the tasks.

CONCLUSIONS

The P. alliacea extract elicited mnemonic effects and improved the learning process in both IA and MWM tests. Our results highlight the importance of further studies in order to identify the active substances of the PaLHE and investigate the pharmacological mechanisms that underlies the reported effects.

Inhibition of the recombinant cattle tick Rhipicephalus (Boophilus) annulatus glutathione S-transferase

Rhipicephalus (Boophilus) annulatus is a bloodsucking ectoparasite that causes severe production losses in the cattle industry. This study aims to evaluate the in vitro effects of tannic acid, hematin (GST inhibitors) and different plant extracts (rich in tannic acid) on the activity of the recombinant glutathione S-transferase enzyme of the Egyptian cattle tick R. annulatus (rRaGST), in order to confirm their ability to inhibit the parasitic essential detoxification enzyme glutathione S-transferase. Extraction with 70% ethanol of Hibiscus cannabinus (kenaf flowers), Punica granatum (red and white pomegranate peel), Musa acuminata (banana peel) (Musaceae), Medicago sativa (alfalfa seeds), Tamarindus indicus (seed) and Cuminum cyminum (cumin seed) were used to assess: (i) inhibitory capacities of rRaGST and (ii) their phenolic and flavonoid contents. Ethanol extraction of red pomegranate peel contained the highest content of phenolic compounds (29.95mg gallic acid/g dry tissue) compared to the other studied plant extracts. The highest inhibition activities of rRaGST were obtained with kenaf and red pomegranate peel (P. granatum) extracts with IC50 values of 0.123 and 0.136mg dry tissue/ml, respectively. Tannic acid was the more effective inhibitor of rRaGST with an IC50 value equal to 4.57μM compared to delphinidine-HCl (IC50=14.9±3.1μM). Gossypol had a weak inhibitory effect (IC50=43.7μM), and caffeic acid had almost no effect on tick GST activity. The IC50 values qualify ethacrynic acid as a potent inhibitor of rRaGST activity (IC50=0.034μM). Cibacron blue and hematin showed a considerable inhibition effect on rRaGST activity, and their IC50 values were 0.13μM and 7.5μM, respectively. The activity of rRaGST was highest for CDNB (30.2μmol/min/mg protein). The enzyme had also a peroxidatic activity (the specific activity equals 26.5μmol/min/mg protein). Both tannic acid and hematin inhibited rRaGST activity non-competitively with respect to GSH and competitively with respect to CDNB. While red pomegranate extracts inhibited rRaGST activity competitively with respect to GSH, uncompetitive inhibition was observed with respect to CDNB.

Insecticidal Activity of Some Traditionally Used Ethiopian Medicinal Plants against Sheep Ked Melophagus ovinus

Twelve medicinal plants and a commercially used drug Ivermectin were examined for insecticidal activity against Melophagus ovinus sheep ked at different time intervals using in vitro adult immersion test. The findings show that at 3.13 µL/mL, 6.25 µL/mL and 12.5 µL/mL concentration of Cymbopogon citratus, Foeniculum vulgare and Eucalyptus globulus essential oils respectively, recorded 100% mortalities against M. ovinus within 3 hour of exposure. Significantly higher insecticidal activity of essential oils was recorded (P = 0.00) when compared to 10  μ g/mL Ivermectin after 3-hour exposure of M. ovinus at a concentration of ≥1.57  μ L/mL, ≥3  μ L/mL, and ≥12.7  μ L/mL essential oils of C. citratus, F. vulgare, and E. globulus, respectively. Among essential oils, C. citratus has showed superior potency at a three-hour exposure of the parasite (P = 0.00) at a concentration of ≥0.78  μ L/mL. Strong antiparasitic activity was recorded by aqueous extract of Calpurnia aurea (80% mortality) at a concentration of 200 mg/mL within 24 h among aqueous extracts of 9 medicinal plants. The results indicated all the four medicinal plants, particularly those tested essential oils, can be considered as potential candidates for biocontrol of M. ovinus sheep ked.

Acaricidal activity of extract of Artemisia absinthium against Rhipicephalus sanguineus of dogs

The objective of the study was to evaluate the in vitro efficacy of different concentrations of chloroform extract obtained from the aerial parts of Artemisia absinthium in comparison to amitraz on adults, eggs and larvae of the dog tick Rhipicephalus sanguineus using the adult immersion test (AIT), egg hatchability test (EHT) and larval packet test (LPT), respectively. Five concentrations of the extract (1.25, 2.5, 5, 10 and 20 %) with three replications for each concentration were used in all the bioassays. A control group was established (water + dimethylsulphoxide) together with a positive control group (amitraz), with three repetitions each. In AIT, the mortality rates were 0.0, 13.3, 16.7, 33.3 and 93.3 % in concentrations of 1.25, 2.5, 5, 10 and 20 %, respectively, and the variation was significant (p=0.0151). The LC50 (CI) and LC95 (CI) values were calculated as 8.793 % (8.217-9.408) and 34.59 % (29.71-40.26), respectively. The egg production was reduced by 6.6, 6.6, 18.3, 42.5 and 85.1 % in the concentrations of 1.25, 2.5, 5, 10 and 20 %, respectively, and it was statistically significant (p=0.0274). In EHT, hatching was completely inhibited at 5, 10 and 20 % displaying 100 % ovicidal action while at the concentrations of 1.25 and 2.5 %, the inhibition rates were 20 and 60 %, respectively. In LPT, the extract caused 100 % mortality of larvae in the concentrations of 5, 10 and 20 % after 24 h while at the concentrations of 1.25 and 2.5 %, the mortality rates were 54.3 and 96.7 %, respectively. The LC50 (CI) and LC95 (CI) values were determined to be 1.11 % (1.099-1.121) and 2.37 % (2.328-2.423), respectively. The results show that the extract of A. absinthium has acaricidal properties and could be useful in controlling R. sanguineus which is an efficient vector of pathogens both in dogs and humans.

Acaricidal properties of two extracts from Guiera senegalensis J.F. Gmel. (Combrataceae) against Hyalomma anatolicum (Acari: Ixodidae)

Laboratory test were carried out on eggs, larvae, nymphs and adults of Hyalomma anatolicum to determine the acaricidal activities of petroleum ether (PE) and crude ethanolic extracts (EE) from the leaves of Guiera senegalensis J.F. Gmel. (Combrataceae) using immersion method. Stock solutions, of 300 mg/ml (30%) of the each two extract, were prepared. Six two-fold serial dilutions each with three replicates were used. Both extracts, at the highest concentration 150 mg/ml (15%), induced 100% failure of hatching of the treated eggs. The concentrations of PE and EE that induced 50% inhibition of the hatchability (IC50) were 1.71 and 0.508%, respectively. In the larval immersion test (LIT), EE at 15% concentration caused complete mortality while the same concentration of PE resulted in 96% mortality. The mortalities increased with concentrations. There was a correlation between the mortalities and increased concentrations, the values of the linear correlation coefficient (r) for PE and EE were 0.93 and 0.79, and The LC50 and LC99 were 2.08 and 14.09, and 0.787 and 11.054, respectively. At the concentrations of 3.75%, 7.5% and 15%, PE inhibited the molting of the nymphs by 40, 55 and 65%, respectively, while EE induced 46.49, 64.3 and 71.4% inhibition, respectively. The effectiveness of the treatment against unfed adult females was assessed by measuring the feeding performance and egg production using adult immersion test (AIT). Although, there was no mortality in unfed adults, PE and EE inhibited feeding and egg-laying of the survived females by 35-100% and 6.16-100%, respectively. Our results indicated that G. senegalensis is a promising biocontrol candidate as an acaricidal agent against H. anatolicum.

In vitro activities of plant extracts from the Brazilian Cerrado and Pantanal against Rhipicephalus (Boophilus) microplus (Acari: Ixodidae)

A total of 73 ethanol extracts from different anatomical parts of 44 plant species belonging to 24 families, native to the Mid-Western region of Brazil, were assessed in vitro for their effect on the reproductive cycle of engorged females of the cattle tick Rhipicephalus (Boophilus) microplus, using the adult immersion test. All extracts were evaluated at the concentration of 0.2 % and, among the extracts tested, the one obtained from the fruits of Guarea kunthiana (Meliaceae) proved to be highly efficacious, showing 99.1 % of product effectiveness. Extracts from other three species were shown to be moderately active, namely Nymphaea amazonum trunk (Nymphaeaceae) [51.7 %], Strychnos pseudoquina trunk (Loganiaceae) [48 %] [corrected] and Ocotea lancifolia leaves (Lauraceae) [34.5 %], while the remaining extracts were shown to be weakly active or inactive. This is the first report on the bioactivity of these species on egg production by engorged females of R. microplus.

Histopathology of the tegument of rabbits infested by Rhipicephalus sanguineus (ACARI: IXODIDAE) ticks and exposed to selamectin (active principle of acaricide Revolution, Pfizer)

Ticks are hematophagous ectoparasites which can transmit several diseases to the host during their feeding process. When ticks mechanically damage the tissue, they eventually induce inflammatory responses on the skin spot where they are fixed. One of the alternatives to control these ectoparasites is the use of chemical substances like selamectin-the active principle of Pfizer's antiparasitic Revolution-a macrocyclic lactone capable of doing neurotoxic damage to the tick and eventually eliminating infestation in dogs and cats. The purpose of this study was to analyze, using histological and histochemical techniques, the occurrence of morphophysiological alterations in the skin of the host rabbits exposed to selamectin and infested with Rhipicephalus sanguineus (Acari: Ixodidae). Histologically, the exposed and infested rabbits showed a partial and/or total decrease in the stratum corneum and the epithelium decreased in the number of cell layers, consequently reducing the stratification (thinning) and quite pronounced formations of sub-epidermal edemas with consequent disorganization of collagen fibers in the dermal layer's connective tissue. Histochemical tests showed strong periodic acid-Schiff-positive reaction in the hair follicle and some regions of the dermis, besides resynthesis of collagen fibers detected by Mallory's trichrome technique. The obtained results showed that selamectin acts like a toxicant agent when in contact with the skin of the rabbit infested with ticks, inducing morphophysiological alterations in the acute inflammatory process in the animal's tegument. Selamectin is a chemical substance which has a dose-dependent action since higher concentrations cause greater morphophysiological damage in the skin of rabbits.

Acaricidal properties of Ricinus communis leaf extracts against organophosphate and pyrethroids resistant Rhipicephalus (Boophilus) microplus

Indian cattle ticks have developed resistance to commonly used acaricides and an attempt has been made to formulate an ecofriendly herbal preparation for the control of acaricide resistant ticks. A 95% ethanolic extract of Ricinus communis was used to test the efficacy against reference acaricide resistant lines by in vitro assay. In in vitro assay, the extract significantly affects the mortality rate of ticks in dose-dependent manner ranging from 35.0 ± 5.0 to 95.0 ± 5.0% with an additional effect on reproductive physiology of ticks by inhibiting 36.4-63.1% of oviposition. The leaf extract was found effective in killing 48.0, 56.7 and 60.0% diazinon, deltamethrin and multi-acaricide resistant ticks, respectively. However, the cidal and oviposition limiting properties of the extract were separated when the extract was fractionated with hexane, chloroform, n-butanol and water. The HPTLC finger printing profile of R. communis leaf extract under λ(max.) - 254 showed presence of quercetin, gallic acid, flavone and kaempferol which seemed to have synergistic acaricidal action. In vivo experiment resulted in 59.9% efficacy on Ist challenge, however, following 2nd challenge the efficacy was reduced to 48.5%. The results indicated that the 95% ethanolic leaf extract of R. communis can be used effectively in integrated format for the control of acaricide resistant ticks.

Novel and simple approach using synthesized nickel nanoparticles to control blood-sucking parasites

The present study was on assessment of the anti-parasitic activities of nickel nanoparticles (Ni NPs) against the larvae of cattle ticks Rhipicephalus (Boophilus) microplus and Hyalomma anatolicum (a.) anatolicum (Acari: Ixodidae), fourth instar larvae of Anopheles subpictus, Culex quinquefasciatus and Culex gelidus (Diptera: Culicidae). The metallic Ni NPs were synthesized by polyol process from Ni-hydrazine as precursor and Tween 80 as both the medium and the stabilizing reagent. The synthesized Ni NPs were characterized by Fourier transform infrared (FTIR) spectroscopy analysis which indicated the presence of Ni NPs. Synthesized Ni NPs showed the X-ray diffraction (XRD) peaks at 42.76°, 53.40°, and 76.44°, identified as 111, 220, and 200 reflections, respectively. Scanning electron microscopy (SEM) analysis of the synthesized Ni NPs clearly showed that the Ni NPs were spherical in shape with an average size of 150 nm. The Ni NPs showed maximum activity against the larvae of R. (B.) microplus, H. a. anatolicum, A. subpictus, C. quinquefasciatus and C. gelidus with LC(50) values of 10.17, 10.81, 4.93, 5.56 and 4.94 mg/L; r(2) values of 0.990, 0.993, 0.992, 0.950 and 0.988 and the efficacy of Ni-hydrazine complexes showed the LC(50) values of 20.35, 22.72, 8.29, 9.69 and 7.83 mg/L; r(2) values of 0.988, 0.986, 0.989, 0.944 and 0.978, respectively. The findings revealed that synthesized Ni NPs possess excellent larvicidal parasitic activity. To the best of our knowledge, this is the first report on larvicidal activity of blood feeding parasites using synthesized Ni NPs.