In vitro acaricidal activity of Cymbopogon citratus, Cymbopogon nardus and Mentha arvensis against Rhipicephalus microplus (Acari: Ixodidae).

The chemical composition and acaricidal activity of plant-derived essential oils was assessed against Rhipicephalus microplus ticks. The essential oils of Mentha arvensis, Cymbopogon citratus and C. nardus were assessed for acaricidal activity against Rhipicephalus microplus. Essential oils (EO) of plants were separated by hydrodistillation (three times) and analyzed using gas chromatography - mass spectrometer (GC-MS). For bioassays, engorged females of R. microplus were exposed to C. citratus and C. nardus EO at 2%, 3%, 4% and 5% concentrations; and to M. arvensis EO at 1%, 3%, and 5% for 5 min. The weight egg mass, nutrient index (N.I), egg production index (E.P.I), hatching and control rate were evaluated. Non-feed larvae of R. microplus were exposed to essential oils with 0.25%, 0.5%; 1%; 1.5% and 2% concentrations; the mortality rate was measured after 48 h. Only engorged females presented reduced biological activities (oviposition, E.P.I) after exposure to M. arvensis at 3%, when in comparison to both positive and negative controls. The hatchability of R. microplus larvae ranged from 66.9% (after exposure to C. nardus EO at 5%) to 99.2% (positive control). The nutrition index was lower (46.6%) for the exposure to M. arvensis EO at 5%. M. arvensis at 3% and 5% concentrations was significantly efficient for engorged females when compared to control (53.7% and 47.5%, respectively). C. citratus EO at 1%, 1.5% and 2% concentrations yielded better results in the larval packet test, causing 100% mortality. Nonetheless, C. nardus and M. arvensis EO at 2% yielded 66% and 39% mortality, respectively. The study showed that M. arvensis presented potential for the control of R. microplus engorged females while C. citratus and C. nardus presented potential as a larvicide.

Lemongrass (Cymbopogon citratus) oil: A promising miticidal and ovicidal agent against Sarcoptes scabiei.

BACKGROUND: Essential oils may represent an alternative strategy for controlling scabies, a neglected tropical disease caused by the infestation of mite from the species Sarcoptes scabiei. Lemongrass (Cymbopogen citratus) oil is reported to possess pharmacological properties including antiparasitc, antioxidant, antimicrobial and anti-inflammatory. The aim of the present study was to assess the potential efficacy of lemongrass oil against the mites and eggs of Sarcoptes scabiei. METHODOLOGY/PRINCIPAL FINDINGS: Mass spectrometry analysis confirmed that the main component presented in lemongrass oil was citral. Lemongrass oil at concentrations of 10% and 5% killed all Sarcoptes mites within 10 and 25 min, respectively. The median lethal concentration value was 1.37%, 1.08%, 0.91%, 0.64%, and 0.48% at 1, 3, 6, 12, and 24 h, respectively. Lemongrass oil at all concentrations (10%, 5%, 1%, 0.5%, 0.1%) was able to significantly decrease the hatching rate of Sarcoptes eggs. CONCLUSIONS/SIGNIFICANCE: Lemongrass oil should be considered as a promising miticidal and ovicidal agent for scabies control.

Efficacy of plants extracts from the Cerrado against adult female of Dermacentor nitens (Acari: Ixodidae).

Dermacentor nitens tick is commonly found in the equine auditory canal, where it causes economic losses due to its direct damage, causing blood spoliation, stress, transmission of pathogens, and predisposition to myasis and secondary bacterial infection in its hosts. In this study we evaluated the effect of ethanolic extracts of Cerrado plants on biological parameters of engorged females of D. nitens. Ethanolic extracts were prepared from the leaves of Schinopsis brasiliensis, Piptadenia viridiflora, Ximenia americana, and Serjania lethalis at 25-150 mg mL-1. Groups of 10 engorged adult females were treated with these extracts and compared with a control containing distilled water and another control with organophosphate, using five replicates for each group. Compared with the control with water, S. lethalis and X. americana extracts at 100 and 150 mg mL-1 significantly inhibited the posture ability. Differently, extracts of S. brasiliensis and P. viridiflora were the most effective in inhibiting larval hatching. Extracts of X. americana and P. viridiflora showed effective inhibition of reproductive parameters of the tick, presenting dose-dependent effect with IC90 78.86 and 78.94 mg mL-1, respectively. Theses effective extracts contained low condensed tannin levels and their HPLC chromatograms revealed the presence of flavonoids. The efficacies of P. viridiflora and X. americana extracts were higher than 90% indicating that these extracts are promising as alternative agents for D. nitens control.

In vitro acaricidal activity of Piper nigrum and Piper longum fruit extracts and their active components against Rhipicephalus (Boophilus) microplus ticks.

In vitro acaricidal activity of Piper nigrum and P. longum fruit extracts and their active components (piperine for P. nigrum and piperine and piperlonguminine for P. longum) was evaluated against adults engorged females of Rhipicephalus (Boophilus) microplus using adult immersion test. Three concentrations of each extract with four replications were used in the bioassay. Extracts significantly affected mortality rates of ticks in dose-dependent manner ranged 12.5-95.8% for P. nigrum and 29.2-87.5% for P. longum, with an additional effect on the reproductive physiology of ticks by inhibiting oviposition (28.1-96.9% by P. nigrum and 36.1-89.3% by P. longum). However, the acaricidal and oviposition limiting properties were decreased significantly when the active component(s) of each extract was tested separately. However, the combination of piperine and piperlonguminine (obtained from P. longum extract) caused 79.2% mortality of ticks which is equivalent to the corresponding concentration (~ 5%) of the extract. It can be concluded that the fruit extracts of P. nigrum and P. longum had both acaricidal and oviposition limiting actions against the adults of R. (B.) microplus which could make it a valuable component of developing sustainable strategy for integrated tick management.

Isolation and characterization of two acaricidal compounds from Calpurnia aurea subsp. aurea (Fabaceae) leaf extract.

The menace caused by ticks and tick-borne diseases is a major limitation to the livestock industry in Africa. The high costs and non-availability of synthetic, chemical acaricides to resource-limited farmers, resistance of ticks to available acaricides and residue problems in meat and milk consumed by humans further complicate matters. The use of plant extracts as a possible source of new acaricides has received much interest in the last decade. In our endeavour to discover natural acaricidal compounds, tick toxicant bioassays were conducted and the chloroform fraction of Calpurnia aurea ethanol leaf extract had good acaricidal activity. Further purification of the fraction revealed two flavonoids, isolated from C. aurea for the first time. These flavonoids were characterized as apigenin-7-O-ß-D-glycoside and isorhoifolin by means of NMR spectroscopic and mass spectrometry analysis. Isorhoifolin was the most potent compound (LC50 = 0.65 mg/ml), was not cytotoxic and should be further investigated for its potential as an acaricidal agent.

Acaricidal, pediculicidal and larvicidal activity of synthesized ZnO nanoparticles using Momordica charantia leaf extract against blood feeding parasites.

The aim of the present study was to evaluate the acaricidal, pediculicidal and larvicidal effect of synthesized zinc oxide nanoparticles (ZnO NPs) using Momordica charantia leaf extract against the larvae of Rhipicephalus (Boophilus) microplus, adult of Pediculus humanus capitis, and the larvae of Anopheles stephensi, Culex quinquefasciatus. The ZnO NPs were characterized by using UV, XRD, FTIR and SEM-EDX. The SEM image confirms that the synthesized nanoparticles were spherical in shape with a size of 21.32 nm. The results of GC-MS analysis indicates the presence of the major compound of Nonacosane (C29H60) in the M. charantia leaf extract. Cattle tick, head lice and mosquito larvae were exposed to a varying concentrations of the synthesized ZnO NPs and M. charantia leaf extract for 24 h. Compared to the leaf aqueous extract, biosynthesized ZnO NPs showed higher toxicity against R. microplus, P. humanus capitis, An. stephensi, and Cx. Quinquefasciatus with the LC50 values of 6.87, 14.38, 5.42, and 4.87 mg/L, respectively. The findings revealed that synthesized ZnO NPs possess excellent anti-parasitic activity. These results suggest that the green synthesized ZnO NPs has the potential to be used as an ideal ecofriendly approach for the control of R. microplus, P. humanus capitis and the mosquito larvae of An. Stephensi and Cx. quinquefasciatus.

Acaricidal Potentials of the Terpene-rich Essential Oils of Two Iranian Eucalyptus Species against Tetranychus urticae Koch.

There is a rapid growth in the screening of plant materials for finding new bio-pesticides. In the present study, the essential oils of E. oleosa and E. torquata leaves were extracted using a Clevenger apparatus and their chemical profiles were investigated by Gas Chromatography-Mass Spectrometry (GC-MS). Among identified compounds, the terpenes had highest amount for both essential oils; 93.59% for E. oleosa and 97.69% for E. torquata. 1,8-Cineole (31.96%), α-pinene (15.25%) and trans-anethole (7.32%) in the essential oil of E. oleosa and 1,8-cineole (28.57%), α-pinene (15.74%) and globulol (13.11%) in the E. torquata essential oil were identified as the main components. The acaricidal activity of the essential oils of E. oleosa and E. torquata were examined using fumigation methods against the adult females of Tetranychus urticae Koch. The essential oils have potential acaricidal effects on T. urticae. The essential oil of E. oleosa with LC50 value of 2.42 µL/L air was stronger than E. torquata. A correlation between log concentration and mite mortality has been observed. Based on the results of present study, it can be stated that the essential oils of E. oleosa and E. torquata have a worthy potential in the management of T. urticae.

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

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

Microwave-assisted extraction of three bioactive alkaloids from Peganum harmala L. and their acaricidal activity against Psoroptes cuniculi in vitro.

ETHNOPHARMACOLOGICAL RELEVANCE: Peganum harmala L. is a perennial herbaceous, glabrous plant that grows in semi-arid conditions, steppe areas and sandy soils. It is used to treat fever, diarrhoea, subcutaneous tumours, arthralgia, rheumatism, cough, amnesia and parasitic diseases in folk medicines. In this paper, we aimed to develop a simpler and faster method for the extraction of three alkaloids from Peganum harmala L. than other conventional methods by optimizing the parameters of a microwave-assisted extraction (MAE) method, and to investigate the acaricidal activities of three compounds against Psoroptes cuniculi. MATERIALS AND METHODS: After optimizing the operating parameters with the single factor experiment and a Box-Behnken design combined with a response-surface methodology, a MAE method was developed for extracting the alkaloids from the seeds, and a high-performance liquid chromatography was used to quantify these compounds. An in vitro experiments were used to study the acaricidal activities. RESULTS: The optimal conditions of MAE method were as follows: liquid-to-solid ratio 31.3:1mL/g, ethanol concentration 75.5%, extraction time 10.1min, temperature 80.7°C, and microwave power 600W. Compared to the heat reflux extraction (HRE, 60min) and the ultrasonic-assisted extraction (UAE, 30min) methods, MAE method require the shortest time (10min) and obtain the highest yield of three compounds (61.9mg/g). Meanwhile, the LT50 values for the vasicine (1.25 and 2.5mg/mL), harmaline (1.25 and 2.5mg/mL), harmine (1.25 and 2.5mg/mL) and MAE extract (100mg/mL) against Psoroptes cuniculi were 12.188h, 9.791h, 11.994h, 10.095h, 11.293h, 9.273h and 17.322h, respectively. CONCLUSIONS: The MAE method developed exhibited the highest extraction yield within the shortest time and thus could be used to extract the active compounds from Peganum harmala L. on an industrial basis. As the active compounds of Peganum harmala L., vasicine, harmalin and harmine presented the marked acaricidal activities against Psoroptes cuniculi, and could be widely applied for the treatments of acariasis in animals.

Efficacy of 11 Brazilian essential oils on lethality of the cattle tick Rhipicephalus (Boophilus) microplus.

Herbal extracts have been investigated as an alternative for parasite control, aiming to slow the development of resistance and to obtain low-cost biodegradable parasiticides. The goal of this study was to evaluate the efficacy, in vitro, of 11 essential oils from Brazil on reproductive efficiency and lethality of the cattle tick Rhipicephalus (Boophilus) microplus. The effects of oils extracted from Curcuma longa, Zingiber officinale, Lippia alba, Lippia gracilis, Lippia origanoides, Lippia sidoides, Mentha arvensis, Mentha piperita, Croton cajucara (white and red), and Croton sacaquinha on ticks were investigated by the Immersion Test with Engorged Females (ITEF) and the modified Larval Packet Test (LPT). Distilled water and 2% Tween 80 were used as control treatments. Chemical analysis of the oils was done with gas chromatography coupled with mass spectrometry. Analysis of the in vitro tests using Probit (SAS program) allowed the calculation of lethal concentrations (LCs). Lower reproductive efficiency indexes and higher efficacy percentages in the ITEF were obtained with the oils extracted from C. longa (24 and 71%, respectively) and M. arvensis oils (27 and 73%, respectively). Lower LC50 was reached with C. longa (10.24 mg/mL), L. alba (10.78 mg/mL), M. arvensis (22.31 mg/mL), L. sidoides (27.67 mg/mL), and C. sacaquinha (29.88 mg/mL) oils. In the LPT, species from Zingiberaceae and Verbenaceae families caused 100% lethality at 25 mg/mL, except for L. sidoides. The most effective oils were from C. longa, L. gracilis, L. origanoides, L. alba, and Z. officinale. The LC50 and LC90 were, respectively: 0.54 and 1.80 mg/mL, 3.21 and 7.03 mg/mL, 3.10 and 8.44 mg/mL, 5.85 and 11.14 mg/mL, and 7.75 and 13.62 mg/mL. The efficacy was directly related to the major components in each essential oil, and the oils derived from Croton genus presented the worst performance, suggesting the absence of synergistic effect among its compounds. Since C. longa, containing 62% turmerone, was the one most efficient against ticks, this compound may be potentially used for tick control, but further research is needed, especially to assess toxicity of these compounds to the host. These new studies, together with the results presented here, may provide a strong rationale for designing pre-clinical and clinical studies with these agents.

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

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

The field efficacy of Lepidium latifolium and Zataria multiflora methanolic extracts against Varroa destructor.

Varroa destructor is the most serious pest of honeybee (Apis mellifera), causing high economic losses in the beekeeping industry worldwide. The intensive utilization of many chemical substances against the mites resulted in resistance development. One of the applicable and alternative treatments being used for their control is plant-derived products (PDSS). The aim of this study was to evaluate the acaricidal activity of Lepidium latifolium and Zataria multiflora leaf extracts on V. destructor in field conditions. Four different concentrations (100, 200, 400, and 500 ppm) of the methanolic extracts were sprayed to treat each colony. The efficacy and side effects on adult bees were compared to Apistan chemical strips (ACSS). The acaricidal activity was the highest (100%) for L. latifolium extract at 500 ppm after 12 days and 86.26% for Z. multiflora. The infestation rate was decreased to 0.0% with L. latifolium and to 13.74% with Z. multiflora. The highest reduction was observed with L. latifolium followed by Z. multiflora extract at 500 ppm concentration. Both of the extracts showed negligible effect on bees, and it can be concluded that these PDSS as biodegradable agents could be used for V. destructor control in honeybee colonies.

Chemical composition and acaricidal activity of the essential oil of Baccharis dracunculifolia De Candole (1836) and its constituents nerolidol and limonene on larvae and engorged females of Rhipicephalus microplus (Acari: Ixodidae).

Baccharis dracunculifolia DC (common name "alecrim-do-campo" in Brazil) is a plant with widespread distribution in South America that is the botanical origin of green propolis. The aim of this study was to evaluate the chemical composition and acaricidal activity of the essential oil of B. dracunculifolia and its constituents nerolidol and limonene on unengorged larvae and engorged females of Rhipicephalus microplus (Acari: Ixodidae). The essential oil yield was 0.8% of dry mass and the major constituents were nerolidol (22.3%), germacrene D (7.2%), limonene (6.9%), ß-pinene (6.7) and bicyclogermacrene (6.5%). The acaricidal activity of the essential oil and the pure compounds nerolidol and (R)-(+)-limonene were assessed in the laboratory through the modified larval packet test (LPT) and the female immersion test (FIT). In the LPT, the essential oil and nerolidol were both active, causing more than 90% mortality at concentrations from 15.0 and 10.0 mg mL(-1), respectively, whereas (R)-(+)-limonene was not active. In the FIT, the oil and nerolidol caused reduction in the quantity and quality of eggs produced, with control percentages of 96.3% and 90.3% at concentrations of 60.0 and 50.0 mg mL(-1), respectively. It can be concluded that the essential oil obtained from the aerial parts of B. dracunculifolia and its major component nerolidol have high activity on R. microplus larvae and engorged females.

Acaricidal activity of petroleum ether extract of leaves of Tetrastigma leucostaphylum (Dennst.) Alston against Rhipicephalus (Boophilus) annulatus.

The acaricidal activity of the petroleum ether extract of leaves of Tetrastigma leucostaphylum (Dennst.) Alston (family: Vitaceae) against Rhipicephalus (Boophilus) annulatus was assessed using adult immersion test (AIT). The per cent of adult mortality, inhibition of fecundity, and blocking of hatching of eggs were studied at different concentrations. The extract at 10% concentration showed 88.96% inhibition of fecundity, 58.32% of adult tick mortality, and 50% inhibition of hatching. Peak mortality rate was observed after day 5 of treatment. Mortality of engorged female ticks, inhibition of fecundity, and hatching of eggs were concentration dependent. The LC50 value of the extract against R. (B.) annulatus was 10.46%. The HPTLC profiling of the petroleum ether extract revealed the presence of at least seven polyvalent components. In the petroleum ether extract, nicotine was identified as one of the components up to a concentration of 5.4%. However, nicotine did not reveal any acaricidal activity up to 20000 ppm (2%). Coconut oil, used as diluent for dissolving the extract, did not reveal any acaricidal effects. The results are indicative of the involvement of synergistic or additive action of the bioactive components in the tick mortality and inhibition of the oviposition.

Clinical efficacy of 9-oxo-10, 11-dehydroageraphorone extracted from Eupatorium adenophorum against Psoroptes cuniculi in rabbits.

BACKGROUND: Animal acariasis is one of the important veterinary skin diseases. Chemical drugs have been widely used to treat and control this kind of disease. But many chemicals control could increase resistance in target species, toxicity and environmental hazards. We found that the 9-oxo-10, 11-dehydroageraphorone (euptox A) extracted from E. adenophorum has strong toxicity against P. cuniculi in vitro, but the in vivo acaricidal actions of euptox A have yet to be investigated. RESULTS: A 14-day experiment was performed using rabbits that were naturally infested with P. cuniculi on a farm. Rabbits were randomly divided into five groups; animals in groups A, B and C were treated in each ear topically with 4.0 ml of 2.0 and 1.0 g/L (w/v) euptox A, respectively. Animals in groups D and E were treated with ivermectin (by injection; positive controls) and glycerol with water only (by embrocation; negative controls), respectively. Each rabbit was treated twice with separate treatments on days 0 and 7. Rabbits were observed daily and detailed examinations were performed on days 0, 7 and 14, to inspect the presence or absence of mites and scabs/crusts. Seven days after the initial treatment, the mean clinical scores (presence of scabs/crusts) decreased from 3.48, 3.37, 3.43 and 3.45 to 0.37, 0.42, 0.78 and 0.38 in the ears of animals in groups A, B , C and D, respectively, which were similar to the observations recorded in the positive control rabbits. However, the clinical score for negative control rabbits did not increase significantly (P > 0.05) during the experiment, and this changed from 3.32 to 3.37 in the ears, and there were no significant differences in clinical efficacy between left and right ears. After two treatments (0 and 7 d), the rabbits in groups A, B, C and D had recovered completely 14 days after the last treatment and no recurrences of infection were observed. CONCLUSIONS: These results indicate that euptox A was potent compounds for the effective control of animal P. cuniculi in vivo.

Acaricidal activity of Ocimum basilicum and Spilanthes acmella against the ectoparasitic tick, Rhipicephalus (Boophilus) microplus (Arachinida: Ixodidae).

The ectoparasitic tick, Rhipicephalus (Boophilus) microplus collected at various cattle farms in and around Chennai was subjected to treatment of different crude solvent extracts of leaves of Ocimum basilicum and Spilanthes acmella for acaricidal activity. Among various solvent extracts of leaves of O. basilicum and S. acmella used, chloroform extract of O. basilicum at concentrations between 6% and 10% exhibited 70% and 100% mortality of ticks when compared to control. The LC50 and LC90 values of the chloroform extract of leaves of O. basilicum treatment on the ticks after 24 h were observed as 5.46% and 7.69%. Quantitative and qualitative analysis of α- and ß- carboxylesterase enzymes in the whole gut homogenate of cattle tick, R. microplus treated with chloroform extract of leaves of O. basilicum revealed higher level of activities for the enzymes. This indicated that there was an induced response in the tick, R. microplus against the toxic effects of the extract of O. basilicum.

Active monoterpene ketones isolated from Rosmarinus officinalis with fumigant and contact action against Tyrophagus putrescentiae (Schrank).

The acaricidal activities of an active material derived from Rosmarinus officinalis oil and its relative monoterpene ketones were determined using fumigant and contact toxicity bioassays against Tyrophagus putrescentiae and were compared with that of a commercial acaricide (benzyl benzoate). The active component of R. officinalis oil, isolated by silica gel column chromatography and high-performance liquid chromatography, was identified as camphor, based on various spectroscopic analyses. In the fumigant toxicity bioassay, camphor (2.25 µg/cm(3)) was 5.58 times more active than benzyl benzoate (12.56 µg/cm(3)) against T. putrescentiae, followed by (+)-camphor (3.89 µg/cm(3)) and (-)-camphor (5.61 µg/cm(3)). In the contact toxicity bioassay, camphor (1.34 µg/cm(2)) was 6.74 times more toxic than benzyl benzoate (9.03 µg/cm(2)) against T. putrescentiae, followed by (+)-camphor (2.23 µg/cm(2)) and (-)-camphor (2.94 µg/cm(2)). These results indicate that camphor and its derivatives are very useful as potential control agents against stored food mites regardless of the application method.

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

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

Acaricidal activity of 9-oxo-10,11-dehydroageraphorone extracted from Eupatorium adenophorum in vitro.

The acaricidal activity of the 9-oxo-10,11-dehydroageraphorone (euptox A), a cadenine sesquiterpene from Eupatorium adenophorum (E. adenophorum) against Sarcoptes scabiei and Psoroptes cuniculi was tested in vitro. A complementary log-log (CLL) model was used to analyze the data of the toxicity tests in vitro. The results showed euptox A had strong toxicity against mites, killing all S. scabiei at 3 and 4 mg/ml (m/v) concentration, while 4 mg/ml euptox A was also found to kill all P. cuniculi within a 4 h period. Similarly, 2, 3 and 4 mg/ml concentration of euptox A had strong toxicity against S. scabiei, with median lethal time (LT50) values at 0.687, 0.526, 0.326 h, respectively. 3 mg/ml and 4 mg/ml showed strong acaricidal action against P. cuniculi; the LT50 values were 0.693 and 0.493 h, respectively. The median lethal concentration (LC50) values were 1.068 mg/ml for Scabies mite and 0.902 mg/ml for P. cuniculi in 2 h. The results indicate that euptox A has strong acaricidal activity and may exploit as novel drugs for the effective control of animal acariasis.

Isolation and identification of acaricidal compounds in Eupatorium adenophorum petroleum ether extract and determination of their acaricidal activity against Psoroptes cuniculi.

We used multiple silica gel column chromatography and thin-layer chromatography coupled with (1)H nuclear magnetic resonance (NMR) and (13)C NMR to separate and identify the active acaricidal ingredients in Eupatorium adenophorum petroleum ether extract. The acaricidal activity of each compound was tested against Psoroptes cuniculi in vitro. Three compounds had strong acaricidal activity against P. cuniculi in vitro. The insecticidal effect of 0.5% compound 9ß-hydroxy-ageraphorone was better than the insecticidal effect of fenvalerate, and compounds 9-oxo-ageraphorone and 9-oxo-10,11-dehydro-ageraphorone exhibited higher insecticidal effects than 9ß-hydroxy-ageraphorone. Thus, the E. adenophorum petroleum ether extract contains an effective composition of acaricides that could potentially be developed as a promising plant-origin acaricide.