Laboratory determination of efficacy of indigenous plant extracts for parasites control

Repellent activity of Vitex negundo and Curcuma longa herbal extract against Simulium species in India

BACKGROUND OBJECTIVES

At present, use of synthetic pesticides to manage insects and other arthropods creates a number of issues that are related to the environment and public health. The goal of the present study is to find repellent activity of Vitex negundo and Curcuma longa herbal extracts against the wild species Simulium (blackfly) bite.

METHODS

We have studied Simulium biting behavior and tested the repellency of herbal extract obtained from Vitex negundo L. (Lamiales: Lamiaceae) and Curcuma longa L. (Zingiberal: Zingiberaceae) along with their essential oils in three locations in Arunachal Pradesh, India on human volunteers' resistance to Simulium (blackflies). The reported herbal extracts were incorporated to topical drug delivery vehicle as a cream and gel.

RESULTS

The methanolic extract of Vitex negundo cream and gel formulation showed >2 h safety at 5% concentration and >5 h safety at 10% concentration in all the testing sites followed by ethyl acetate extract. Whereas, chloroform extract of Curcuma longa cream and gel formulation provided >1 h safety at 5% concentration and >4 h safety at 10% concentration.

INTERPRETATION CONCLUSION

At an optimum concentration of 10%, the methanolic extract of Vitex negundo cream provided complete protection times (CPTs) 320.4, 358.6, and 346.4 min, respectively. These findings offer confirmation of the methanolic extract and chloroform extract potential for use in new blackfly repellents.

In vitro and in silico study on the seeds of Veitchia merrillii on trematode worms

Background and Aim

The potential of plants as anthelmintics is very large, but there is still very little research conducted in the search for effective, safe, easily obtained, and affordable anthelmintic candidates. Palem putri (Veitchia merrillii) is an ornamental plant that is interesting to study because it is included in the areca nut group which is reported to have strong abilities as anthelmintics. The study aims to evaluate the anthelmintic efficacy of Veitchia merrillii against trematode worms such as Paramphistomum spp. and Fasciola hepatica.

Materials and Methods

This research employs both in vitro and computational techniques. An anthelmintic in vitro test was carried out on Paramphistomum spp. worms at concentrations of 10%, 25%, and 40% (gr/v), assessing mortality index as the observable outcome, followed by a histopathological investigation of the deceased worms for tissue and cellular damage evaluation. Seventeen compounds from V. merrillii seeds were studied in silico for their anthelmintic activity against F. hepatica worms using the quantitative structure-activity relationship technique, molecular docking, and Lipinski's rule analysis for orally administered medication.

Results

About 25% and 40% extracts of V. merrillii damaged the tegument organs in the worms. Seventeen compounds in V. merrillii seed extract, on average, yielded a higher anthelmintic index on F. hepatica than praziquantel. Eleven of the 17 compounds exhibit stronger affinity than praziquantel, with routine and gallic acid being the top two ligands (∆Gbinding values: -11.65 kcal/mol and -11.07 kcal/mol, respectively). According to Lipinski's rule analysis, only routine compounds cannot be orally administered.

Conclusion

The seeds of V. merrilli have potential as an anthelmintic agent for Paramphistomum spp. at concentrations of 25%-40% (gr/v).

Bioactive components in Psidium guajava extracts elicit biotoxic attributes and distinct antioxidant enzyme modulation in the larvae of vectors of lymphatic filariasis and dengue

Control of mosquito vectors, which have caused a global disease burden, has employed various methods. However, the challenges posed by current physical and chemical methods have raised concerns about vector control programs, leading to the search for alternative methods that are less toxic, eco-friendly, and cost-effective. This study investigated the larvicidal potential of aqueous, methanol, and ethylacetate extracts of Guava (Psidium guajava) against Aedes aegypti and Culex quinquefasciatus larvae. Functional group and phytochemical characterization were performed using Fourier-Transform Infrared Spectroscopy (FTIR) and GC-MS analysis to identify the bioactive compounds in the extracts. Larval bioassays were conducted using WHO standard procedures at concentrations of 12.5, 25, 50, 125, and 250 mg/L, and mortality was recorded after 24, 48, and 72 h. Additionally, antioxidant enzyme profiles in the larvae were studied. All of the solvent extracts showed larvicidal activity, with the methanol extract exhibiting the highest mortality against Ae. aegypti and Cx. quinquefasciatus larvae, followed by aqueous and ethylacetate extracts. FTIR spectroscopic analysis revealed the presence of OH, C-H of methyl and methylene, CO and CC. The GC-MS analysis indicated that the methanol, aqueous, and ethylacetate extracts all had 27, 34, and 43 phytoactive compounds that were effective at causing larvicidal effects, respectively. Different concentrations of each extract significantly modulated the levels of superoxide dismutase, catalase, glutathione peroxidase, and reduced glutathione in larvae. This study's findings indicate the potential for developing environmentally friendly vector control products using the bioactive components of extracts from P. guajava leaves.

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.

The anthelmintic potentials of medicinal plant extracts and an isolated compound (rutin, C27H30O16) from Terminalia catappa L. against Gastrothylax crumenifer

Paramphistomosis is a pathogenic disease that occurs frequently in tropical and subtropical countries including Thailand. This disease is affected in the parasites causing severe gastrointestinal disorders and death in infected animals. In the present study, we examined the anthelmintic efficacy of albendazole (ABZ) and crude plant extracts from barks of Bombax ceiba L., Diospyros rhodocalyx Kurz. and Vitex glabrata R.Br., and leaves of Terminalia catappa L. and Cassia alata L. against Gastrothylax crumenifer. The hightest anthelmintic activity on the parasites after 24 h incubation was observed in the n-butanol extract of T. catappa leaf. In this study, fractionation bioassay of n-butanol extract of T. catappa leaf was conducted to both separation and discrimination of rutin served as a new efficient compound (LC₅₀ = 28.96; LC₉₀ = 88.75 μg/mL) against G. crumenifer. This compound was confirmed by ¹H nuclear magnetic resonance (¹H NMR), ¹³C NMR, infrared (IR) and ultraviolet (UV) spectra as well as mass spectra data. The rutin-treated parasites with all dosages showed swift decrease of the motility and the relative motility (RM) and survival index (SI) were decreased obviously from 3 h until flukes were killed after 12 h of incubation. When observed with light microscopy, the parasites showed the earliest change in a limited region of the tegument. When observed by scanning electron microscopy, the parasites' tegument exhibited similar sequences of surface changes after treatments with rutin and ABZ, but less severity in ABZ treatment. The sequences of changes comprised swelling of folds and ridges, formation of blebbing, rupturing of blebs, erosions, lesions and the tegument demolition. Hence, rutin could be considered as the potential anthelmintic agent for treatment of paramphistomosis.

Phytosterol, Lipid and Phenolic Composition, and Biological Activities of Guava Seed Oil

Plant seeds have been found to contain bioactive compounds that have potential nutraceutical benefits. Guava seeds (Psidium guajava) are by-products in the beverage and juice industry; however, they can be utilized for a variety of commercial purposes. This study was designed to analyze the phytochemicals of the n-hexane extract of guava seed oil (GSO), to study its free-radical scavenging activity, and to monitor the changes in serum lipids and fatty acid profiles in rats that were fed GSO. The GSO was analyzed for phytochemicals using chromatographic methods. It was also tested for free-radical scavenging activity in hepatoma and neuroblastoma cells, and analyzed in terms of serum lipids and fatty acids. GSO was found to contain phenolic compounds (e.g., chlorogenic acid and its derivatives) and phytosterols (e.g., stimasterol, β-sitosterol and campesterol), and exerted radical-scavenging activity in cell cultures in a concentration-dependent manner. Long-term consumption of GSO did not increase cholesterol and triglyceride levels in rat serum, but it tended to decrease serum fatty acid levels in a concentration-dependent manner. This is the first study to report on the lipid, phytosterol and phenolic compositions, antioxidant activity, and the hepato- and neuro-protection of hydrogen peroxide-induced oxidative stress levels in the GSO extract.

Antiarthritic Activity of Achyranthes Aspera on Formaldehyde - Induced Arthritis in Rats

AIM

To determine the ameliorative potential of aqueous extract of Achyranthesaspera(AEAA) against arthritis using swiss albino mice and Wistar rats, and its possible mechanism of action.

METHODS

Swiss albino mice (25-30 g) and Wistar rats (150-180 g) under standard controlled conditions (24 ± 2°C, 50-70 humidity and 12 h light/dark cycle). The groups were divided into 6 groups (n = 6/group) and assigned as control, negative control, standard and, formaldehyde supplemented with two different test dose groups of A. aspera for 4 weeks. Arthritis induced by subplantar administration of 0.1 ml formaldehyde (2% v/v) into the left hind paw in all groups except normal control. Arthritis was assessed using serum Hb, ESR, paw volume, joint diameter, radiological and histopathological investigation.

RESULTS

Oral administration of AEAA shown a significant (p < 0.01) dose-dependent protection against formaldehyde induced arthritis. At 21st day, A.asperashown an inhibition of paw volume in the different doses of 250 mg/kg and 500 mg/kg were found to be 30% and, 38.33% respectively. At 14th day the joint swelling was found to be 27.2% and 36.36 respectively. Diclofenac (10 mg/kg) had an effect of 36.61% inhibition of arthritis and joint swelling at 21st and 14th day.

CONCLUSION

Thus, the present study revealed that the aqueous extract of A. aspera offered significant protection against arthritis and joint inflammation.

Effect of acaricidal components isolated from lettuce (Lactuca sativa) on carmine spider mite (Tetranychus cinnabarinus Boisd.)

This study aimed to evaluate the acaricidal activity of lettuce (Lactuca sativa) extracts against carmine spider mites (Tetranychus cinnabarinus Boisd.) and isolate the acaricidal components. Acaricidal activities of lettuce extracts isolated from different parts (the leaf, root and seed) using various solvents (petroleum ether, acetone and methanol) were evaluated with slide-dip bioassay and relatively high median lethal concentration (LC50) values were detected. Acetone extracts of lettuce leaves harvested in July and September were fractionated and isolated with silica gel and thin-layer chromatography. Consequently, acetone extracts of lettuce leaves harvested in July exhibited higher acaricidal activity than those harvested in September, with an LC50 value of 0.268 mg ml-1 at 72 h post-treatment. A total of 27 fractions were obtained from the acetone extract of lettuce leaves harvested in July, and mite mortalities with the 11th and 12th fractions were higher than those with the other 25 fractions (LC50: 0.751 and 1.258 mg ml-1 at 48 h post-treatment, respectively). Subsequently, active acaricidal components of the 11th fraction were identified by infrared, nuclear magnetic resonance and liquid chromatography/mass spectrometry. Five components were isolated from the 11th fraction, with components 11-a and 11-b showing relatively high acaricidal activities (LC50: 0.288 and 0.114 mg ml-1 at 48 h post-treatment, respectively). Component 11-a was identified as β-sitosterol. In conclusion, acetone extracts of lettuce leaves harvested in July might be used as a novel phytogenic acaricide to control mites.

Therapecutic efficacy of the leaf extract of Croton joufra Roxb. against experimental cestodiasis in rats

The leaves of Croton joufra have been used as a traditional medicine in Assam (Northeast India) to treat the intestinal helminthic infections. The aim of this study was to establish the in vitro and in vivo anthelmintic efficacy of the leaf extract of this plant on Hymenolepis diminuta, a zoonotic tapeworm. The plant extract was also screened for its chemical constituents. The in vitro anthelmintic efficacy of the plant was evaluated by physical motility test on adult cestodes, following their exposure to 10, 20, 30 mg/ml concentrations of the crude leaf extract, while the in vivo effect was determined based on the eggs per gram (EPG) counts and worm recovery rates, using an experimentally induced model of H. diminuta infections in Wistar rats. The in vitro study results showed a dose-dependent effect on the parasite and the highest concentration of the extract (30 mg/ml) caused mortality of the worms in 1.53 ± 0.12 h as compared to 3.46 ± 0.10 h shown by 1 mg/ml concentration of the reference drug, praziquantel (PZQ). The in vivo results showed that a single 800 mg/kg dose of the extract, given for 3 days, was highly efficacious against adult parasites as it reduced the EPG count and worm burdens of rats by 94.74 and 75 %, respectively. The extract also showed almost similar degree of effects against the larval stage of the parasite. As ascertained by the qualitative screening tests, the leaf extract of C. joufra contains terpenoids, tannins, alkaloids, flavonoids, glycosides and reducing sugar. The overall findings of this study suggest that C. joufra leaf extract possesses significant anthelmintic efficacy and support its traditional anthelmintic claims.

Anthelmintic effect of Psidium guajava and Tagetes erecta on wild-type and Levamisole-resistant Caenorhabditis elegans strains

ETHNOPHARMACOLOGICAL RELEVANCE

Psidium guajava and Tagetes erecta have been used traditionally to treat gastrointestinal parasites, but their active metabolites and mechanisms of action remain largely unknown.

AIM OF THE STUDY

To evaluate the anthelmintic potential of Psidium guajava and Tagetes erecta extracts on Levamisole-sensitive and Levamisole-resistant strains of the model nematode Caenorhabditis elegans.

MATERIALS AND METHODS

Aqueous extracts of Psidium guajava (PGE) and Tagetes erecta (TEE) were assayed on locomotion and egg-laying behaviors of the wild-type (N2) and Levamisole-resistant (CB193) strains of Caenorhabditis elegans.

RESULTS

Both extracts paralyzed wild-type and Levamisole-resistant nematodes in a dose-dependent manner. In wild-type worms, TEE 25mg/mL induced a 75% paralysis after 8h of treatment and PGE 25mg/mL induced a 100% paralysis after 4h of treatment. PGE exerted a similar paralyzing effect on N2 wild-type and CB193 Levamisole-resistant worms, while TEE only partially paralyzed CB193 worms. TEE 25mg/mL decreased N2 egg-laying by 65% with respect to the untreated control, while PGE did it by 40%.

CONCLUSIONS

Psidium guajava leaves and Tagetes erecta flower-heads possess hydrosoluble compounds that block the motility of Caenorhabditis elegans by a mechanism different to that of the anthelmintic drug Levamisole. Effects are also observable on oviposition, which was diminished in the wild-type worms. The strong anthelmintic effects in crude extracts of these plants warrants future work to identify their active compounds and to elucidate their molecular mechanisms of action.

In vitro and in vivo anthelmintic effects of Caesalpinia bonducella (L.) Roxb. leaf extract on Hymenolepis diminuta (Cestoda) and Syphacia obvelata (Nematoda)

Background:

Leaves of Caesalpinia bonducella (L.) Roxb. have been traditionally used as an herbal remedy to treat the intestinal helminthic infections in traditional medicine of India.

Aim:

This study was undertaken to evaluate the potential in vitro and in vivo anthelmintic effects of C. bonducella leaf extract against Syphacia obvelata (Nematoda) and Hymenolepis diminuta (Cestoda).

Materials and Methods:

The in vitro anthelmintic activity of the extract was investigated on adult worms of S. obvelata (Nematoda) and H. diminuta (Cestoda) in terms of physical motility and mortality of parasites. The in vivo study was performed in H. diminuta-rat model and S. obvelata-mice model, by monitoring the egg per gram of feces count and worm count of animals following the treatment with different doses of plant extract.

Results:

The study recorded significant and dose-dependent anthelmintic effects of the extract on both the parasites. In the in vitro study, 30 mg/ml concentration of extract caused mortality of H. diminuta in 2.5 ± 0.2 h and S. obvelata in 3.57 ± 0.16 h. In the in vivo study, the extract showed a comparatively better efficacy on S. obvelata, where its 800 mg/kg dose revealed 93% reduction of worm load in mice, as compared to 85% worm load reduction of H. diminuta in rats.

Conclusions:

The findings suggest that leaf extract of C. bonducella possesses significant anthelmintic effects and supports its use as an anthelmintic in traditional medicine. This appears to be the first report of in vivo anthelmintic activity of C. bonducella against these parasites.

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.

Ethnobotany of medicinal plants used in Antakya: A multicultural district in Hatay Province of Turkey

ETHNOPHARMACOLOGICAL RELEVANCE

We have compiled information about the medicinal plants used in folk medicine in the district of Antakya. Since its establishment by King Seleucus I in 300 B.C., Antakya (old Antioch) has hosted nearly 20 civilizations. Antakya, neighboring Northwestern Syria, is located on the western end of the "Silk Road" and was one of the great centers of Graeco-Roman world. Today, Antakya is a cosmopolitan city in which Arabic and Turkish are widely spoken, and where distinct ethnic and religious communities, such as Arab Alawite, Arab Christian, Arab Sunni, Turk Sunni, Armenian, and Jewish, have been living together in harmony for centuries. In addition, the rich flora in the vicinity of Antakya also renders the area interesting in terms of ethnobotanical fieldwork.

AIM OF THE STUDY

This study aimed to compile the information about plants used for medicinal purposes by local people in the district of Antakya. This city is a significant region in terms of ethnobotanical fieldwork, owing to its cosmopolitan structure, long history, relatively preserved traditional community structure, and rich flora. Furthermore, we sought to compare the ethnomedicinal data geographically, cross-culturally, and historically.

MATERIALS AND METHODS

The ethnobotany of medicinal plants used in the district of Antakya has been investigated through two separate studies; one was conducted in 1975, interviewing 29 people, and the other was conducted in 2011-2013, interviewing 182 people. The use value (UV) and informant consensus factor (FIC) values of the plants were calculated. In order to interpret the authenticity and sources of the compiled ethnomedicinal information, previous publications that contain information about the similar medicinal uses of plants identified in our region were reviewed and evaluated meticulously. A comparison with the data obtained from other regions of Turkey and from other Mediterranean regions, as well as a cross-cultural analysis between the ethnic groups within the study area, was performed by implementation of the Jaccard index (JI) RESULTS: Throughout the study, information about 202 medicinal plant taxa was compiled. Among these plants, 39 have either not yet been mentioned in ethnobotanical or medicinal studies, or have been used for a medicinal purpose other than those encountered in the literature review. The ethnomedicinal information we gathered from the study area exhibits close similarities to the ethnomedicinal information of other Southern and Eastern Mediterranean countries where Arabic is spoken, as well as to that of Northern and Western Mediterranean countries where Latin languages are spoken. In addition to these similarities, in most cases, this ethnomedicinal information shows hybrid features of ethnomedicinal knowledge from Eastern and Western Mediterranean countries.

CONCLUSION

Based on a literature survey, we found that the cited medicinal uses for 43 plants have also been corroborated by other various biological testings. This finding strongly suggests the importance of ethnobotanical studies in the development of new medicines. We believe that this study has compiled rich ethnomedicinal information that reflects the cosmopolitan structure of Antakya in a very good way.

Annona muricata leaf extract-mediated silver nanoparticles synthesis and its larvicidal potential against dengue, malaria and filariasis vector

Mosquitoes transmit several diseases which cause millions of deaths every year. The use of synthetic insecticides to control mosquitoes caused diverse effects to the environment, mammals, and high manufacturing cost. The present study was aimed to test the larvicidal activity of green synthesized silver nanoparticles using Annona muricata plant leaf extract against third instar larvae of three medically important mosquitoes, i.e., Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus. The different concentrations of green synthesized Ag Nanoparticles (AgNPs; 6, 12, 18, 24, 30 μg mL(-1)) and aqueous crude leaf extract (30, 60, 90, 120, 150 μg mL(-1)) were tested against the larvae for 24 h. Significant larval mortality was observed after the treatment of A. muricata for all mosquitoes with lowest LC50 and LC90 values, viz., A. aegypti (LC50 and LC90 values of 12.58 and 26.46 μg mL(-1)), A. stephensi (LC50 and LC90 values of 15.28 and 31.91 μg mL(-1)) and C. quinquefasciatus (LC50 and LC90 values of 18.77 and 35.72 μg mL(-1)), respectively. The synthesized AgNPs from A. muricata were highly toxic than aqueous crude extract. The nanoparticle characterization was done using spectral and microscopic analysis, namely UV-visible spectroscopy which showed a sharp peak at 420 nm of aqueous medium containing AgNPs, X-ray diffraction (XRD) analysis revealed the average crystalline size of synthesized AgNPs (approximately 45 nm), and Fourier transform infrared spectroscopy (FTIR) study exhibited prominent peaks 3381.28, 2921.03, 1640.17, 1384.58, 1075.83, and 610.77 cm(-1). Particle size analysis (PSA) showed the size and distribution of AgNPs (103 nm); field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) analysis showed a spherical shape, size range from 20 to 53 nm; and energy-dispersive X-ray spectroscopy (EDX) reflects the chemical composition of synthesized AgNPs. Heat stability of the AgNPs was confirmed between the temperatures 20 to 70 °C. The result suggests that green synthesized AgNPs from A. muricata has the potential to be used as a low-cost and eco-friendly approach for the control of selected mosquitoes.

Evaluation of plant-mediated synthesized silver nanoparticles against vector mosquitoes

Diseases transmitted by blood-feeding mosquitoes, such as dengue fever, dengue hemorrhagic fever, Japanese encephalitis, malaria, and filariasis, are increasing in prevalence, particularly in tropical and subtropical zones. To control mosquitoes and mosquito-borne diseases, which have worldwide health and economic impacts, synthetic insecticide-based interventions are still necessary, particularly in situations of epidemic outbreak and sudden increases of adult mosquitoes. Green nanoparticle synthesis has been achieved using environmentally acceptable plant extract and eco-friendly reducing and capping agents. In view of the recently increased interest in developing plant origin insecticides as an alternative to chemical insecticide, in the present study, the adulticidal activity of silver nanoparticles (AgNPs) synthesized using Heliotropium indicum plant leaf extract against adults of Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus was determined. Adult mosquitoes were exposed to varying concentrations of aqueous extract of H. indicum and synthesized AgNPs for 24 h. AgNPs were rapidly synthesized using the leaf extract of H. indicum, and the formation of nanoparticles was observed within 6 h. The results recorded from UV-vis spectrum, Fourier transform infrared, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy support the biosynthesis and characterization of AgNPs. The maximum efficacy was observed in synthesized AgNPs against the adult of A. stephensi (lethal dose (LD)₅₀ = 26.712 μg/mL; LD₉₀ = 49.061 μg/mL), A. aegypti (LD₅₀ = 29.626 μg/mL; LD₉₀ = 54.269 μg/mL), and C. quinquefasciatus (LD₅₀ = 32.077 μg/mL; LD₉₀ = 58.426 μg/mL), respectively. No mortality was observed in the control. These results suggest that the leaf aqueous extracts of H.indicum and green synthesis of AgNPs have the potential to be used as an ideal eco-friendly approach for the control of the A. stephensi, A. aegypti, and C. quinquefasciatus. This is the first report on the adulticidal activity of the plant extracts and AgNPs.

Present and future potential of plant-derived products to control arthropods of veterinary and medical significance

The use of synthetic pesticides and repellents to target pests of veterinary and medical significance is becoming increasingly problematic. One alternative approach employs the bioactive attributes of plant-derived products (PDPs). These are particularly attractive on the grounds of low mammalian toxicity, short environmental persistence and complex chemistries that should limit development of pest resistance against them.

Several pesticides and repellents based on PDPs are already available, and in some cases widely utilised, in modern pest management. Many more have a long history of traditional use in poorer areas of the globe where access to synthetic pesticides is often limited. Preliminary studies support that PDPs could be more widely used to target numerous medical and veterinary pests, with modes of action often specific to invertebrates.

Though their current and future potential appears significant, development and deployment of PDPs to target veterinary and medical pests is not without issue. Variable efficacy is widely recognised as a restraint to PDPs for pest control. Identifying and developing natural bioactive PDP components in place of chemically less-stable raw or 'whole’ products seems to be the most popular solution to this problem. A limited residual activity, often due to photosensitivity or high volatility, is a further drawback in some cases (though potentially advantageous in others). Nevertheless, encapsulation technologies and other slow-release mechanisms offer strong potential to improve residual activity where needed.

The current review provides a summary of existing use and future potential of PDPs against ectoparasites of veterinary and medical significance. Four main types of PDP are considered (pyrethrum, neem, essential oils and plant extracts) for their pesticidal, growth regulating and repellent or deterrent properties. An overview of existing use and research for each is provided, with direction to more extensive reviews given in many sections. Sections to highlight potential issues, modes of action and emerging and future potential are also included.

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.

Cassia alata L: potential role as anthelmintic agent against Hymenolepis diminuta

The efficacy of Cassia alata against cestode Hymenolepis diminuta was evaluated in our study. Worms were maintained between rat model and beetle. Air-dried leaves of C. alata were subjected to ethanol extraction. Different concentrations (10-80 mg/ml) of the extract were prepared in phosphate buffer saline and tested on the parasite in vitro. Parasites treated with C. alata showed a decrease in motility with an increase in concentrations and complete immobilization took lesser time compared to control. The paralyzed parasites were further processed for electron microscopic studies. Ultrastructural micrographs revealed swelling of the tegument and blebbing on the tegumental surface throughout the body accompanied with destruction of microtriches and changes such as shrinkage in the scolex region. Depletion of parenchyma cells and destruction in the connective tissues along with sparsely cytoplasmic cytons were also observed, and these observations are similar with worms treated with a known drug praziquantel. These results may suggest that the plant leaves could be considered for controlling helminth infection and can represent a step forward in the search for alternative anthelmintic drug.

Effects of aqueous extract of Capsicum frutescens (Solanaceae) against the fish ectoparasite Ichthyophthirius multifiliis

Ichthyophthirius multifiliis is an important fish ectoparasite that often results in significant economic losses to freshwater aquaculture. The search of alternative substances to control infections of I. multifiliis became stringent after malachite green, an effective and widely used chemotherapeutant, is banned on fish farms because of its carcinogenicity and teratogenicity. In this study, the effects of the aqueous extract of Capsicum frutescens, which is readily available and affordable, were evaluated under in vitro and in vivo conditions. The results in the in vitro conditions showed that the aqueous extracts of C. frutescens with the ratios (V (SS)/V (T)-V (SS), the volume of stock solution; V (T), the volume of total solution) of 1:32 and 1:64 led to more than 70 % mortality of I. multifiliis theronts during 4 h of exposure and significantly reduced the survival of the tomonts and the total number of theronts released by the tomonts within 22 h (P < 0.05). A 96-h bioassay was carried out to determine the acute toxicity of the aqueous extract of C. frutescens to goldfish. No visible effect was observed in the treatments with the aqueous extracts of C. frutescens with the ratios (V (SS)/V (T)) of 1:32, 1:64 and 1:128, while in the other treatments, the erratic behaviour of fish was noted. In addition, in vitro tests demonstrated that the aqueous extract of C. frutescens had an adverse effect on I. multifiliis trophonts in situ. Fish treated with the aqueous extracts of C. frutescens in ratios V (SS)/V (T) of 1:32 and 1:64 carried significantly fewer parasites than the control and the other treatments (P < 0.05). These results suggest, therefore, that aqueous extracts of C. frutescens have potential for the control of ichthyophthiriasis in the aquaculture industry, though further phytochemical studies will need to be performed for isolation and identification of the active compounds.

In vivo anthelmintic activity of Clerodendrum colebrookianum Walp., a traditionally used taenicidal plant in Northeast India

Although there are several effective drugs available for the treatment of intestinal helminths, the fact remains that they continue to remain out of reach to a vast majority of people in the world, especially in developing countries. On the other hand, there are a great many herbal remedies that are effective against common intestinal worms and are easily available to common people in developing countries. Clerodendrum colebrookianum Walp. (Lamiaceae) is a perennial shrub which is native to South and Southeast Asia. Traditionally, the leaves of this plant are used by the indigenous people of Northeast India as a remedy for the treatment of intestinal tapeworm infections. The aim of this study was to evaluate and authenticate the anthelmintic efficacy of C. colebrookianum leaf extract in experimentally induced Hymenolepis diminuta (a zoonotic tapeworm) infections in Wistar rats. The efficacy of the plant extract was assessed by monitoring the eggs per gram of faeces (EPG) counts and worm recovery rates of experimental animals, following treatment with the leaf extract of this plant at three different doses, i.e. 200, 400 and 800 mg/kg body weight, each given singly for 5 days. The results obtained revealed that the leaf extract of C. colebrookianum possesses a dose-dependent efficacy against the larval, immature and adult stages of H. diminuta. However, the efficacy of the extract was found to be considerably high only against the adult stages of the parasite. For this stage, a single 800-mg/kg dose of extract, given for 5 days, resulted into 68.42% reduction in the EPG counts and 62.50% reduction in the worm counts in the extract-treated group of animals, as compared to the control. The reference drug, praziquantel (5 mg/kg, single dose), however, showed slightly better efficacy and caused 95.16 and 87.00% reductions in the EPG and worm counts of treated animals, respectively. Unlike the adult stages, the efficacy of the plant extract was recorded to be comparatively low against the larval and immature stages of the parasite, as the treatment of animals with the highest dose of extract (800 mg/kg) could cause only 37.50 and 54.00% reductions in worm counts, respectively. The experimental evidence obtained in this study suggests that leaves of C. colebrookianum possess significant anthelminthic properties and supports their use against intestinal tapeworm infections in traditional medicine.

Tick prevention at a crossroad: new and renewed solutions

Ticks have major economic impact through diseases they transmit, direct losses due to their detrimental effect and the efforts invested in prevention measures directed against them. Chemical acaricides represent the main line of anti-tick defense in both humans and domestic animals, but increasing concerns regarding development of acaricide resistance, especially in the cattle tick Rhipicephalus microplus, and environmental safety issues indicate the need for other, less aggressive but equally efficient methods. This paper aims to evaluate the potential, the scientific and economical limitations and future research directions regarding different alternative methods of tick control and their use in integrated pest management, with a separate reference to the pet industry. New research data in each field is presented and the economical aspects for each approach are individually emphasized.

Repellent activity of some essential oils against Simulium species in India

Use of repellents seems to be most reliable method of personal protection against annoyance and infections associated with haematophagous insects. We have investigated the biting activity of Simulium and tested the repellency of five essential oils extracted from Homalomena aromatica Schott (Alismatales: Araceae), Pogostemon heyneanus Bentham (Lamiales: Lamiaceae), Citrus aurantifolia Swingle (Sapindales: Rutaceae), Vitex negundo L. (Lamiales: Lamiaceae), and Ageratum conzoides L. (Asterales: Asteraceae) on the human volunteers against Simulium (blackflies) in three locations of Arunachal Pradesh, India. Blackflies preferred biting legs (> 79%) as compared to hand and face with profound biting activity during 1000-1100 h (> 23%) and 1500 - 1600 h (> 28%). The essential oil extracted from Homalomena aromatica, Vitex negundo and Ageratum conizoides provided > 2 h protection at 5% concentration and > 5 h protection at 10% concentration in all the three testing locations. The repellency of Homalomena aromatica, Vitex negundo and Ageratum conizoides essential oils after 6 h application was > 50% at 5% concentration and > 90% at 10% concentration. The study provides evidence for the potential of these essential oils in developing new repellents against blackflies.

Efficacy of adulticidal and larvicidal properties of botanical extracts against Haemaphysalis bispinosa, Hippobosca maculata, and Anopheles subpictus

The aim of the present study was to investigate the adulticidal and larvicidal activity of dried leaf hexane, ethyl acetate, acetone, and methanol extracts of Nelumbo nucifera, Manilkara zapota, Ipomoea staphylina, and Acalypha indica against the adults of Haemaphysalis bispinosa (Acarina: Ixodidae), hematophagous fly Hippobosca maculata (Diptera: Hippoboscidae), and fourth instar larvae of malaria vector Anopheles subpictus (Diptera: Culicidae). Parasites were exposed to varying concentrations of plant extracts for 24 h. All extracts showed moderate parasitic effects; however, the percent parasitic mortality observed in the crude leaf hexane, ethyl acetate, acetone, and methanol extracts of N. nucifera and M. zapota against H. bispinosa were 80, 74, 72, and 100 and 100, 83, 74, and 91, respectively, and the activity for I. staphylina and A. indica against Hip. maculata were 100, 93, 87, and 66 and 78, 90, 87, and 100 at 2,000 ppm, respectively; the larvicidal activity for the same extracts of I. staphylina against A. subpictus were 76, 82, 84, and 100 at 100 ppm, respectively. The maximum efficacy was observed in the leaf methanol extract of N. nucifera, hexane extract of M. zapota and leaf hexane extract of I. staphylina, and methanol extract of A. indica against the adults of H. bispinosa and Hip. maculata with LC(50) and LC(90) values of 437.14 and 200.81, and 415.14 and 280.72 ppm, 1,927.57 and 703.52 ppm, and 1,647.70 and 829.39 ppm, respectively. The effective larvicidal activity was observed in leaf methanol extract of I. staphylina against A. subpictus with LC(50) and LC(90) values of 10.39 and 37.71 ppm, respectively. Therefore, this study provides the first report on the adulticidal and larvicidal activity of crude solvent extracts. This is an ideal eco-friendly approach for the control of H. bispinosa, Hip. maculata, and the medically important vector A. subpictus.

Insecticidal activity of the essential oil from fruits and seeds of Schinus terebinthifolia Raddi against African malaria vectors

BACKGROUND

Alternative insecticides for the control of malaria and filarial vectors are of paramount need as resistance is increasing among classes of insecticides currently in use in the public health sector. In this study, mosquitocidal activity of Schinus terebinthifolia essential oil against Anopheles gambiae s.s., An. arabiensis and Culex quinquefasciatus was assessed in laboratory, semi- field and full- field conditions

METHOD

Twenty third instar larvae of both Anopheles gambiae s.s. and Cx. quinquefasciatus were exposed to different dosages of plant extract in both laboratory and semi- field environments. Observation of the mortality response was assessed at intervals of 12, 24, 48 and 72 hours. Adult semi- gravid female mosquitoes were exposed to papers treated with S. terebinthifolia and compared with WHO standard paper treated with alphacypermethrin (0.05%).

RESULTS

Gas chromatography, coupled to mass spectrometry, identified 15 compounds from S. terebinthifolia extracts, the most abundant identified compound was δ-3-carene (55.36%) and the least was γ-elemene (0.41%). The density of the oil was found to be 0.8086 g/ml. The effective dosages in the insectary ranged from 202.15 to 2625.20 ppm and were further evaluated in the semi- field situation. In the laboratory, the mortality of Cx. quinquefasciatus ranged from 0.5 to 96.75% while for An. gambiae s.s it was from 13.75 to 97.91%. In the semi- field experiments, the mortality rates observed varied for both species with time and concentrations. The LC50 and LC95 value in the laboratory was similar for both species while in the semi- field they were different for each. In wild, adult mosquitoes, the KT50 for S. terebinthifolia was 11.29 minutes while for alphacypermethrin was 19.34 minutes. The 24 hour mortality was found to be 100.0% for S. terebinthifolia and 75.0% for alphacypermethrin which was statistically significant (P < 0.001).

CONCLUSION

The efficacy shown by essential oils of fruits and seeds of S. terebinthifolia has given an opportunity for further investigation of individual components of these plant extracts and to evaluate them in small- scale field trials.

Biolarvicidal compound gymnemagenol isolated from leaf extract of miracle fruit plant, Gymnema sylvestre (Retz) Schult against malaria and filariasis vectors

Owing to the fact that the application of synthetic larvicide has envenomed the surroundings as well as non-target organisms, natural products of plant origin with insecticidal properties have been tried as an indigenous method for the control of a variety of insect pests and vectors in the recent past. Insecticides of plant origin have been extensively used on agricultural pests and, to a very limited extent, against insect vectors of public health importance, which deserve careful and thorough screening. The use of plant extracts for insect control has several appealing features as these are generally more biodegradable, less hazardous and a rich storehouse of chemicals of diverse biological activities. Moreover, herbal sources give a lead for discovering new insecticides. Therefore, biologically active plant materials have attracted considerable interest in mosquito control study in recent times. The crude leaf extracts of Gymnema sylvestre (Retz) Schult (Asclepiadaceae) and purified gymnemagenol compound were studied against the early fourth-instar larvae of Anopheles subpictus Grassi and Culex quinquefasciatus Say (Diptera: Culicidae). In the present study, bioassay-guided fractionation of petroleum ether leaf extract of G. sylvestre led to the separation and identification of gymnemagenol as a potential new antiparasitic compound. Phytochemical analysis of G. sylvestre leaves revealed the presence of active constituents such as carbohydrates, saponins, phytosterols, phenols, flavonoids and tannins. However, cardiac glycosides and phlobatannins are absent in the plant extracts. Quantitative analysis results suggested that saponin (5%) was present in a high concentration followed by tannins (1.0%). The 50 g powder was loaded on silica gel column and eluted with chloroform-methanol-water as eluents. From that, 16 mg pure saponin compound was isolated and analysed by thin layer chromatography using chloroform and methanol as the solvent systems. The structure of the purified triterpenoid fraction was established from infrared (IR), ultraviolet (UV), (1)H nuclear magnetic resonance (NMR), (13)C NMR and mass spectral data. The carbon skeleton of the compound was obtained by (13)C NMR spectroscopy. The chemical shift assignments obtained for gymnemagenol from (1)H NMR correspond to the molecular formula C(30)H(50)O(4). The compound was identified as 3β, 16β, 28, 29-tetrahydroxyolean-12-ene (gymnemagenol sapogenin). Parasite larvae were exposed to varying concentrations of purified compound gymnemagenol for 24 h. The results suggested that the larval mortality effects of the compound were 28%, 69%, 100% and 31%, 63%, 100% at 6, 12 and 24 h against A. subpictus and C. quinquefasciatus, respectively. In the present study, the per cent mortality were 100, 86, 67, 36, 21 and 100, 78, 59, 38 and 19 observed in the concentrations of 1,000, 500, 250, 125 and 62.75 ppm against the fourth-instar larvae of A. subpitcus and C. quinquefasciatus, respectively. The purified compound gymnemagenol was tested in concentrations of 80, 40, 20, 10 and 5 ppm, and the per cent mortality were 100, 72, 53, 30 and 15 against A. subpitcus and 100, 89, 61, 42 and 30 against C. quinquefasciatus, respectively. The larvicidal crude leaf extract of G. sylvestre showed the highest mortality in the concentration of 1,000 ppm against the larvae of A. subpictus (LC(50) = 166.28 ppm, r (2) = 0.807) and against the larvae of C. quinquefasciatus (LC(50) = 186.55 ppm, r (2) = 0.884), respectively. The maximum efficacy was observed in gymnemagenol compound with LC(50) and r (2) values against the larvae of A. subpictus (22.99 ppm, 0.922) and against C. quinquefasciatus (15.92 ppm, 0.854), respectively. The control (distilled water) showed nil mortality in the concurrent assay.

Perspectives for the use of plant extracts to control the cattle tick Rhipicephalus (Boophilus) microplus

The evolution of resistance of Rhipicephalus (Boophilus) microplus to synthetic acaricides has given rise to the need for new scientific investigations on alternative ways to control this tick. In this regard, various studies on plants have been developed in an attempt to find extracts with acaricidal properties. Evaluations on plant extracts for controlling R. (B.) microplus have grown intensely over the last decade. There are many advantages from using plant extracts: for example, they can be used in organic cattle farming or even replace synthetic acaricides and they are associated with lower environmental and food contamination, slower development of resistance and lower toxicity to animals and humans. In vitro studies on plant extracts have shown promising results, but most of these extracts have not been tested on animals to validate their use. Difficulties in preparing proper formulations, differences in the chemical composition of plants of the same species due to extrinsic and intrinsic factors and sparse information on active acaricide compounds are hindrances that need to be addressed in order to enable progress within this scientific field.

Screening for feeding deterrent activity of herbal extracts against the larvae of malaria vector Anopheles subpictus Grassi

This no-choice, laboratory study focuses on the feeding of homogeneous powdered, dried, yeast with different plant extracts on mosquito fourth-instar larvae to determine the effects on their mortality. Screening for antifeedant activity of plant extracts with some known medicinal attributes could lead to the discovery of new agents for vector control. The aim of this study was to investigate the antifeedant activity of crude leaf hexane, ethyl acetate, acetone, and methanol extracts of Andrographis lineata Wallich ex Nees. (Acanthaceae), Anisomeles malabarica (L.) Sims. (Lamiaceae), Argemone mexicana L. (Papaveraceae), Aristolochia bracteolata Lam. (Aristolochiaceae), Chrysanthemum indium L. (Asteraceae), Datura metal L. (Solanaceae), Eclipta prostrata L. (Asteraceae), and Sesbania grandiflora (L.) Pers. (Fibaceae) against the fourth-instar larvae of Anopheles subpictus Grassi (Diptera:Culicidae). All the crude extracts showed antifeedant activity in a dose-dependent manner. The plant extracts exhibited a significant antifeedant activity after 24 and 48 h of exposure; however, the highest larval mortality was found in leaf ethyl acetate extract of A. malabarica, acetone extract E. prostrata, methanol extract of A. lineata, C. indium, and S. grandiflora after 24 h (LC(50) = 2.53, 2.82, 2.31, 2.56, and 2.08 mg/mL; LC(90) = 6.40, 8.06, 7.45, 6.98, and 6.20 mg/mL), respectively. The hexane extract of A. lineata, D. metal, methanol extract of A. bracteolata and E. prostrata showed larval mortality after 48 h (LC(50) = 3.05, 2.11, 3.00, and 2.18 mg/mL; LC(90) = 9.06, 6.22, 8.23, and 5.77 mg/mL), respectively. One hundred percent larval mortality was observed in methanol extract of A. lineata, and C. indium after 24 h and the hexane extract of A. lineata and D. metal after 48 h at 10 mg/100 mL. The methanol extracts of A. lineata and C. indium significantly increased larval mortality in comparison to larvae fed with untreated diet. Bacillus thuringiensis subsp. israelensis is widely accepted as a biological pesticide because of its highly specific activity against dipteran insects without adverse effects on other organisms. The feeding deterrent activity of different herbal extracts against the larvae of malaria vector A. subpictus exhibited significantly lower toxicity compare with the bio larvicides, B. thuringiensis. These results suggest that the methanol extract of A. lineata, C. indium, the hexane extract of A. lineata and D. metal have the potential to be used as an ideal eco-friendly approach for the control of the medically important vector A. subpictus. These findings corroborate traditional insecticidal application of selected plants and the results can be extended for the control of mosquitoes.

Anti-leishmanial effects of purified compounds from aerial parts of Baccharis uncinella C. DC. (Asteraceae)

Species of Baccharis exhibit antibiotic, antiseptic, wound-healing, and anti-protozoal properties, and have been used in the traditional medicine of South America for the treatment of several diseases. In the present work, the fractionation of EtOH extract from aerial parts of Baccharis uncinella indicated that the isolated compounds caffeic acid and pectolinaringenin showed inhibitory activity against Leishmania (L.) amazonensis and Leishmania (V.) braziliensis promastigotes, respectively. Moreover, amastigote forms of both species were highly sensible to the fraction composed by oleanolic + ursolic acids and pectolinaringenin. Caffeic acid also inhibited amastigote forms of L. (L.) amazonensis, but this effect was weak in L. (V.) braziliensis amastigotes. The treatment of infected macrophages with these compounds did not alter the levels of nitrates, indicating a direct effect of the compounds on amastigote stages. The results presented herein suggest that the active components from B. uncinella can be important to the design of new drugs against American tegumentar leishmaniases.

In vitro acaricidal effect of tannin-rich plants against the cattle tick Rhipicephalus (Boophilus) microplus (Acari: Ixodidae)

The objectives of this study were to evaluate the in vitro acaricidal effects of lyophilized extracts of four tannin rich plants (Acacia pennatula, Piscidia piscipula, Leucaena leucocephala and Lysiloma latisiliquum) against diverse stages of Rhipicephalus (Boophilus) microplus, and to asses whether tannins were involved in the acaricidal effect using polyethylene glycol (PEG) to block tannins. Larval immersion (LIT) and adult immersion (AIT) tests were used to evaluate the acaricidal effect of each of the lyophilized extracts against larval and adult stages of R. microplus respectively. Larvae and adult ticks were exposed to increasing concentrations of each plant extract (0, 1200, 2400, 4800, 9600 and 19,200 μg ml(-1)) for 10 min. Larval mortality was recorded at 48 h post-incubation. Adult mortality was recorded daily over 14 days, at which point their reproductive efficiency was evaluated. PEG was added to the extracts to verify whether tannins were involved in the acaricidal effect. The effect on egg laying inhibition and larval mortality was analyzed using the GLM procedure in SAS. A Kruskal-Wallis test was used to assess the effect of PEG on LIT results. Calculation of the lethal concentration 50 (LC50) was performed using a probit analysis. All extracts reduced the viability of R. microplus larval stages (P<0.001), and viability was restored with the addition of PEG suggesting an important role of tannins in the acaricidal effect (P<0.001). The LC50 values of L. latisiliquum and P. piscipula plant extracts were 6.402 and 2.466 μg ml(-1). None of the tannin-rich plant extracts affected adult mortality (P>0.05). Lysiloma latisiliquum extract inhibited egg hatching of R. microplus (P<0.01). Tannin-rich plant extracts from A. pennatula, P. piscipula, L. leucocephala and L. latisiliquum showed potential acaricidal activity. Further in vivo studies are needed to confirm this finding.

Adulticidal and larvicidal efficacy of some medicinal plant extracts against tick, fluke and mosquitoes

The adulticidal and larvicidal effect of indigenous plant extracts were investigated against the adult cattle tick Haemaphysalis bispinosa Neumann, 1897 (Acarina: Ixodidae), sheep fluke Paramphistomum cervi Zeder, 1790 (Digenea: Paramphistomatidae), fourth instar larvae of malaria vector, Anopheles subpictus Grassi and Japanese encephalitis vector, Culex tritaeniorhynchus Giles (Diptera: Culicidae). The aim of this study was to evaluate the toxic effect of leaf hexane, chloroform, ethyl acetate, acetone and methanol extracts of Annona squamosa L., Centella asiatica (L.) Urban, Gloriosa superba L., Mukia maderaspatensis (L.) M.Roem, Pergularia daemia (Forsk.) Chiov. and Phyllanthus emblica L. were exposed to different concentrations. All plant extracts showed moderate toxic effect on parasites after 24h of exposure; however, the highest mortality was found in leaf hexane extract of A. squamosa, methanol extracts of G. superba and P. emblica against H. bispinosa (LC(50)=145.39, 225.57 and 256.08ppm); methanol extracts of C. asiatica, G. superba, P. daemia and P. emblica against P. cervi (LC(50)=77.61, 60.16, 59.61, and 60.60ppm); acetone, ethyl acetate extracts of A. squamosa, methanol extract of C. asiatica, acetone extracts of G. superba, ethyl acetate, hexane and methanol extracts of P. daemia against A. subpictus (LC(50)=17.48, 18.60, 26.62, 18.43, 34.06, 13.63, and 50.39ppm); and chloroform, ethyl acetate extracts of A. squamosa, ethyl acetate extract of P. daemia, ethyl acetate and methanol extracts of P. emblica against C. tritaeniorhynchus (LC(50)=63.81, 60.01, 31.94, 69.09, and 54.82ppm), respectively. These results demonstrate that methanol extracts of C. asiatica, G. superba, P. daemia and P. emblica extracts may serve as parasites control even in their crude form.