Natural Acaricides Research Articles

Acaricidal, repellent, and oviposition-deterrent activities of 2,4-di-tert-butylphenol and ethyl oleate against the carmine spider mite Tetranychus cinnabarinus

Tetranychus cinnabarinus (Boisduval) is highly polyphagous and is considered one of the most important crop pests, infesting over 100 crop species grown in field and greenhouse crops worldwide. The control of this mite is still based primarily on the use of synthetic chemical pesticides. In this study, 2,4-di-tert-butylphenol (DTBP) and ethyl oleate (EO) were investigated for their acaricidal, repellent, and oviposition-deterrent properties against T. cinnabarinus under laboratory conditions. Both DTBP and EO exhibited significantly adulticidal, larvicidal, and ovicidal activities against T. cinnabarinus in a concentration-dependent manner after treatment, with LC50 values of 1,256.51, 625.39, and 743.64 ppm for DTBP and 1,621.57, 859.25, and 987.26 ppm for EO, respectively. The mites exhibited the highest run-off rate on bean leaf surfaces sprayed with both DTBP and EO when applied at sub-lethal doses and moved toward surfaces that had not been sprayed with these compounds, according to Pearson’s χ 2 test. Furthermore, not only in a choice assay but also in a no-choice assay, a significant difference was found using an ANOVA between the numbers of eggs laid on bean leaves that were sprayed with DTBP and EO at sub-lethal doses compared to the number laid on unsprayed bean leaves. Additionally, stability assays revealed that EO was more sensitive to environmental factors than DTBP. These results demonstrate that the two compounds DTBP and EO have potential for development as new, natural acaricides for controlling carmine spider mites.

Acaricidal activity of compounds from Cinnamomum camphora (L.) Presl against the carmine spider mite, Tetranychus cinnabarinus.

Tetranychus cinnabarinus (Boisduval) is one of the most important, highly polyphagous pests of a wide range of field and greenhouse crops throughout the world. The control of this mite is still based primarily on the use of synthetic chemical pesticides. In this study, we screened eight plant extracts from China and evaluated the natural compounds showing acaricidal properties from the plant extract, considering their potential use as an alternative to synthetic pesticides. In bioassay screening assays, the Cinnamomum camphora (L.) Presl extract showed significantly greater acaricidal activity against T. cinnabarinus than the other seven plant extracts tested. Five compounds were identified from the C. camphora extract via repeated column chromatography and gas chromatography-mass spectrometry analysis. All the compounds presented acaricidal activity, with 2,4-di-tert-butylphenol and ethyl oleate exhibiting the greatest activity. At 7 days after treatment in a potted seedling experiment, the LC50 values of 2,4-di-tert-butylphenol and ethyl oleate were found to be 1850.94 and 2481.65 mg kg(-1) respectively. Microscopic observations showed that the mites displayed the symptomology of poisoning. These results demonstrated that the C. camphora extract and its two active components show the potential to be developed as new natural acaricides for controlling carmine spider mites.

Acaricidal Activity of Constituents Derived from Peppermint Oil against Tyrophagus putrescentiae

The acaricidal activities of peppermint oil and menthol isomers against mites in stored food were evaluated using fumigant and contact bioassays and were compared with the activity of benzyl benzoate as a synthetic acaricide. Based on the 50% lethal dose (LD50) values against Tyrophagus putrescentiae in the fumigant bioassay, menthol (0.96 μg/cm(2)) was approximately 12.18 times more effective than benzyl benzoate (11.70 μg/cm(2)), followed by (+)-neomenthol (1.33 μg/cm(2)), (-)-menthol (1.60 μg/cm(2)), and (+)-menthol (1.90 μg/cm(2)). In the filter paper bioassay, menthol (0.55 μg/cm(2)) was about 15.18 times more active than benzyl benzoate (8.35 μg/cm(2)), followed by (-)-menthol (0.84 μg/cm(2)), (+)-menthol (0.92 μg/cm(2)), and (+)-neomenthol (1.72 μg/cm(2)). However, (+)-isomenthol did not exhibit any acaricidal activity against T. putrescentiae in the fumigant and filter paper bioassays. These results indicate that peppermint oil and menthol isomers could be effective natural acaricides for managing mites in stored food.

English

Dorobo, a sub-ethnic group of Maasai tribe in Tanzania, live in very remote areas without health facilities and hence depends entirely on plant and animal products for food and medicines. This paper describes attitude, beliefs and use of traditional medicines amongst Dorobo people, with a particular prominence to Commiphora swynertonii plant because of the reported extensive use by the Dorobo for treatment of a multitude of diseases both in humans and livestock. Information was collected via focus group discussion (FGD) held in Erkesumet Township and Kitwai village in Simanjiro District, Manyara Region, Tanzania, between July and August, 2013. It was found out that Dorobos without regard to status or wealth use ethno-botanic medicines as first-line except for serious or recalcitrant diseases. They believe that herbal medicines are readily available, effective and affordable and have no side effects compared to modern medicines. C. swynertonii, the most popularly used plant is used to cleanse the body and protect or treat various diseases such as sexually transmitted infections, skin infections, worm infestation, coughs and other chest problems in both humans and livestock. The bark exudate is used to kill or repel ticks and other insects on livestock and poultry. Dorobos are worried about the future sustainability of ethnobotanical knowledge and availability of medicinal plants because of human developmental activities that are advancing in their living environs. Key words: Commiphora swynertonii, Oltemwai, natural acaricide, Dorobo, ethnobotanical knowledge.

Verbenone Structural Analogues Isolated from Artemesia aucheri as Natural Acaricides against Dermatophagoides spp. and Tyrophagus putrescentiae

The acaricidal activities of Artemisia aucheri oil and (1S)-(-)-verbenone structural analogues were evaluated using a fumigant method against Dermatophagoides farinae , Dermatophagoides pteronyssinus , and Tyrophagus putrescentiae and then compared to those of benzyl benzoate. On the basis of the LD50 values against D. farinae , (1S)-(-)-verbenone (1.38 μg/cm(2)) was about 7.4 times more active than benzyl benzoate (10.15 μg/cm(2)), followed by (+)-trans-myrtanol (2.27 μg/cm(2)), (-)-trans-myrtanol (2.30 μg/cm(2)), and A. aucheri oil (8.75 μg/cm(2)). (1S)-(-)-Verbenone (1.25 μg/cm(2)) was approximately 7.8 times more effective against D. pteronyssinus than benzyl benzoate (9.80 μg/cm(2)), followed by (+)-trans-myrtanol (2.18 μg/cm(2)), (-)-trans-myrtanol (2.22 μg/cm(2)), and A. aucheri oil (8.46 μg/cm(2)). In the case of T. putrescentiae , (1S)-(-)-verbenone (3.75 μg/cm(2)) was roughly 3.5 times more toxic than benzyl benzoate (13.25 μg/cm(2)), followed by (+)-trans-myrtanol (12.57 μg/cm(2)), (-)-trans-myrtanol (12.95 μg/cm(2)), and A. aucheri oil (11.55 μg/cm(2)). These results indicate that A. aucheri oil and (1S)-(-)-verbenone structural analogues may be effective natural agents to control house dust and storage mites.

Changes in Acaricidal Potency by Introducing Functional Radicals and an Acaricidal Constituent Isolated from Schizonepeta tenuifolia

The acaricidal potential of an active constituent isolated from Schizonepeta tenuifolia oil and its structurally related derivatives was evaluated using filter paper and impregnated cotton fabric disk bioassays against house dust and stored food mites. The acaricidal constituent of S. tenuifolia oil was isolated by chromatographic techniques and identified as 2-isopropyl-5-methylcyclohexanone by GC-MS, (1)H-, and (13)C NMR spectra. 2-Isopropyl-5-methylcyclohexanone was a potent acaricide against house dust and stored food mites, based on the LD50 values from the filter paper and impregnated cotton fabric disk bioassays, followed by 4-isopropylcyclohexanone, 2-isopropylidene-5-methylcyclohexanone, 2-methylcyclohexanone, 3-methylcyclohexanone, 4-methylcyclohexanone, and benzyl benzoate. Furthermore, 4-isopropylcyclohexanone and 2-isopropyl-5-methylcyclohexanone, which were introduced on the isopropyl (C3H7) functional radical of the cyclohexanone skeleton, had the highest acaricidal potency. These results indicate that S. tenuifolia oil and 2-isopropyl-5-methylcyclohexanone structural analogues could be effective natural acaricides for managing house dust and stored food mites.

Food Protective Effects of the Active Constituent Isolated from Ostericum praeteritum against the Stored Food Mite, Tyrophagus putrescentiae

The acaricidal effects of the active constituent isolated from Ostericum praeteritum oil and its derivatives were compared with that of benzyl benzoate using fumigant and contact toxicity bioassays against Tyrophagus putrescentiae mites. The active compound of O. praeteritum was isolated by various chromatographic techniques and was identified as 3-methylphenol (C7H8O). On the basis of 50 % lethal dose values, 3-methylphenol (1.42 μg/cm(2)) was determined to be 9.18 times more effective than benzyl benzoate (13.04 μg/cm(2)), followed by 6-fluoro-3-methylphenol (2.18 μg/cm(2)), 4-isopropyl-3-methylphenol (2.53 μg/ cm(2)), and 6-chloro-3-methylphenol (4.03 μg/cm(2)), against Tyrophagus putrescentiae mites in the fumigant bioassay. In the contact toxicity bioassay, 3-methylphenol (1.03 μg/cm(2)) was the most-toxic compound against T. putrescentiae mites, followed by 6-fluoro-3-methylphenol (2.09 μg/cm(2)), 4-isopropyl-3-methylphenol (2.11 μg/cm(2)), 6-chloro-3-methylphenol (3.78 μg/cm(2)), and benzyl benzoate (10.33 μg/cm(2)). These results indicate that the introduction of chloro, isopropyl, and fluoro functional groups to the 3-methylphenol skeleton increased the acaricidal activity. Therefore, 3-methylphenol and its derivatives could potentially be used as natural acaricides against T. purescentiae.

Acaricidal activities of bicyclic monoterpene ketones from Artemisia iwayomogi against Dermatophagoides spp.

The acaricidal properties of 1,7,7-trimethylbicyclo[2.2.1]heptan-2-one isolated from Artemisia iwayomogi and its structural analogues were evaluated against Dermatophagoides farinae and D. pteronyssinus, and their effects were compared with that of the commercial acaricide benzyl benzoate. Based on the 50 % lethal dose (LD50) values against D. farinae, 1,7,7-trimethylbicyclo[2.2.1]heptan-2-one (0.82 μg/cm(2)) was 9.71 times more effective than benzyl benzoate (7.96 μg/cm(2)), followed by (1R)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-one (1.03 μg/cm(2)), (1S)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-one (1.58 μg/cm(2)), and (1R)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-one oxime (3.05 μg/cm(2)) in a filter paper bioassay. The acaricidal activities of 1,7,7-trimethylbicyclo[2.2.1]heptan-2-one and its structural analogues against D. pteronyssinus were similar to those against D. farinae. These results demonstrate that naturally occurring A. iwayomogi-isolated 1,7,7-trimethylbicyclo[2.2.1]heptan-2-one and its structural analogues are suitable for the production of natural acaricides against house dust mites.

Acaricidal Potentials of Active Properties Isolated from Cynanchum paniculatum and Acaricidal Changes by Introducing Functional Radicals

This study evaluated the acaricidal activities of acetophenone and its derivatives for their potentials as natural acaricides using an impregnated fumigant bioassay against Dermatophagoides spp. and Tyrophagus putrescentiae . On the basis of the LD50 values against D. farinae, 3'-methoxyacetophenone (0.41 μg/cm(2)) was 89.9 times more toxic than DEET (36.87 μg/cm(2)), followed by 4'-methoxyacetophenone (0.52 μg/cm(2)), 2'-methoxyacetophenone (0.75 μg/cm(2)), 2'-hydroxy-5'-methoxyacetophenone (1.03 μg/cm(2)), 2'-hydroxy-4'-methoxyacetophenone (1.29 μg/cm(2)), acetophenone (1.48 μg/cm(2)), 2'-hydroxyacetophenone (1.74 μg/cm(2)), 2',5'-dimethoxyacetophenone (1.87 μg/cm(2)), 2',4'-dimethoxyacetophenone (2.10 μg/cm(2)), and benzyl benzoate (9.92 μg/cm(2)). In regard to structure-activity relationships between acaricidal activity and functional radicals (hydroxyl and methoxy groups) on the acetophenone skeleton, a monomethoxy group (2'-, 3'-, and 4'-methoxyacetone) on the acetophenone skeleton was more toxic than were the other groups (2',4'- and 2',5'-dimethoxyacetophenone, 2'- and 4'-hydroxyacetophenone, 2'-hydroxy-4'-methoxyacetophenone, 2'-hydroxy-5'-methoxyacetophenone, and 4'-hydroxy-3'-methoxyacetophenone). These results indicated that acaricidal activity against three mite species changed with the introduction of functional radicals (hydroxyl and methoxy groups) onto the acetophenone skeleton.

Constituents of volatile compounds derived from Melaleuca alternifolia leaf oil and acaricidal toxicities against house dust mites

The acaricidal activities of the volatile compounds derived from Melaleuca alternifolia leaf oil were evaluated against house dust mites. Terpinen-4-ol (3.89 and 3.51 μg/cm2) was approximately 2.0 and 1.7 times more active than benzyl benzoate (7.83 and 5.96 μg/cm2). Therefore, terpinen-4-ol could be useful as a natural acaricide.

Acaricidal activity of essential oils from five endemic conifers of New Caledonia on the cattle tick Rhipicephalus (Boophilus) microplus

The aim of the present study was to demonstrate acaricidal activity on the cattle tick Rhipicephalus (Boophilus) microplus of essential oils from endemic conifers of New Caledonia in the context of the development of natural alternatives. Acaricidal activity of essential oils extracted from resin and heartwood of five endemic conifers of New Caledonia (Araucaria columnaris, Agathis moorei, Agathis ovata, Callitris sulcata, and Neocallitropsis pancheri) was evaluated on 14- to 21-day-old Rhipicephalus microplus tick larvae using the Larval Packal Test bioassay. A first screening with 5% dilute solution was carried out and the oils with 100% of mortality at this rate were diluted until no activity was shown. The heartwood oils of the two Cupressaceae were the most active with LC50 value of 0.65% for C. sulcata and 0.55% for N. pancheri while resin oil of A. columnaris (LC50=1.62%) was the most active of the Araucariaceae family. Negative control (ethanol) was not toxic to the larvae. The chemical composition of essential oil from resin of A. columnaris was analyzed by gas chromatography-mass spectrometry. The essential oil was characterized by high level of sesquiterpene hydrocarbons and oxygenated sesquiterpenes and was composed mainly of aromadendrene (23.1%) and bicyclogermacrene (16.0%). In order to compare different plant resources in a sustainable program of natural acaricide, an "essential oil efficiency EOE" can be measured as the ratio between the yield of extraction and LC50 value. This study shows that A. columnaris (EOE=2.36) and N. pancheri (EOE=3.51) could provide valuable and effective natural acaricides for control of the cattle tick R. microplus.

Acaricidal activity of 31 essential oils extracted from plants collected in Tunisia

The two-spotted spider mite Tetranychus urticae Koch is a worldwide pest, feeding on a large variety of plant families. As its resistance to acaricides spreads rapidly, it is crucial to develop new biological control tactics to manage its populations. In this respect, essential oils may be a good alternative, as they are currently considered minimum-risk pesticides. In this paper, we conducted a series of laboratory experiments to determine the susceptibility of adult females to 31 essential oils extracted from plants collected from Tunisia and compare it with the results obtained with two synthetic acaricides (spirodiclofen and fenbutatin oxide). Details of the essential oil yield of these plants were also recorded. A maximum yield of 0.5% was obtained. Laboratory bioassay indicated that the development of the tetranychid mite population was significantly affected by the use of Deverra scoparia, Haplophyllum tuberculatum, Chrysanthemum coronarium and Mentha pulegium plant extracts that killed 97%, 93%, 93% and 91% of T. urticae, respectively. The chemical composition of the most effective extracts were characterized by gas chromatography–mass spectrometry (GC–MS) and fast GC–flame ionization detector (FID). The evaluation of the potential of biologically active plant volatiles against T. urticae might provide a new approach to the development of natural acaricides to be used both in biological and integrated pest management strategies for controlling two-spotted spider mites.

Acaricidal Toxicity of 2′-Hydroxy-4′-methylacetophenone Isolated from Angelicae koreana Roots and Structure–Activity Relationships of Its Derivatives

The acaricidal activities of 2'-hydroxy-4'-methylacetophenone derived from Angelica koreana roots and its derivatives against Dermatophagoides farinae, Dermatophagoides pteronyssinus, and Tyrophagus putrescentiae were examined by vapor phase and contact toxicity bioassays. In the vapor phase toxicity bioassay, 2'-methylacetophenone (1.25 μg/cm(2)) was 8.0 times more toxic against D. farinae than benzyl benzoate (10.00 μg/cm(2)), followed by 3'-methylacetophenone (1.26 μg/cm(2)), 4'-methylacetophenone (1.29 μg/cm(2)), 2'-hydroxy-4'-methylacetophenone (1.75 μg/cm(2)), and 2'-hydroxy-5'-methylacetophenone (1.96 μg/cm(2)). In the contact toxicity bioassay, 3'-methylacetophenone (0.58 μg/cm(2)) was 17.24 times more effective against D. farinae than benzyl benzoate (7.52 μg/cm(2)), followed by 2'-methylacetophenone (0.64 μg/cm(2)), 2'-hydroxy-4'-methylacetophenone (0.76 μg/cm(2)), 4'-methylacetophenone (0.77 μg/cm(2)), and 2'-hydroxy-5'-methylacetophenone (1.16 μg/cm(2)). The acaricidal activities of 2'-hydroxy-4'-methylacetophenone derivatives against D. pteronyssinus and T. putrescentiae were similar to those against D. farinae. In terms of structure-activity relationships, acaricidal activity against the three mite species changed with the introduction of hydroxyl and methyl functional groups onto the acetophenone skeleton. Furthermore, some of 2'-hydroxy-4'-methylacetophenone derivatives could be useful for natural acaricides against three mite species.

Effect of Crude Plant Extracts on Mushroom Mite,Luciaphorussp. (Acari: Pygmephoridae)

The use of plant extracts for controlling agricultural pests has become increasingly popular in the recent years. Mushroom mite,Luciaphorussp., is a destructive pest of several mushroom species and has been reported to cause severe loss of mushroom cultivation in many settings. The efficacies of 23 rhizome and leaf extracts were evaluated against female adults ofLuciaphorussp. At 3 days after treatment, the rhizome extracts derived fromCurcuma xanthorrhizaRoxb. andZingiber montanum(Koenig) Link ex Dietr. were found to have very strong acaricidal activities, resulting in 100% mite mortality, followed byCurcuma longaLinn. (98.89%),Zingiber zerumbet(L.) Smith. (97.78%),Kaempferia parvifloraWall. Ex Baker (88.89%), andZingiber officinaleRoscoe. (84.44%). The leaf extracts ofOcimum sanctumLinn. andMelissa officinalisL. also resulted in 100% mite mortality 3 days after treatment, while the other leaf extracts induced mite mortality only below 70%. The results suggested that rhizome extracts ofC. xanthorrhizaandZ. montanumand leaf extracts ofO. sanctumandM. officinalishave a great potential for future development as natural acaricides for controllingLuciaphorussp.

Acaricidal Activities of Apiol and Its Derivatives from Petroselinum sativum Seeds against Dermatophagoides pteronyssinus, Dermatophagoides farinae, and Tyrophagus putrescentiae

The acaricidal effects of an active constituent derived from Petroselinum sativum seeds and its derivatives were determined using impregnated fabric disk bioassay against Dermatophagoides farinae , Dermatophagoides pteronyssinus , and Tyrophagus putrescentiae and compared with that of synthetic acaricide. The acaricidal constituent of P. sativum was isolated by various chromatographic techniques and identified as apiol. On the basis of LD(50) values against D. farinae and D. pteronyssinus, apiol (0.81 and 0.94 μg/cm(2)) was 12.4 and 10.2 times more toxic than benzyl benzoate (10.0 and 9.58 μg/cm(2)), respectively. In acaricidal studies of apiol derivatives, 3,4-methylenedioxybenzonitrile (0.04, 0.03, and 0.59 μg/cm(2)) was 250, 319, and 20.7 times more toxic than benzyl benzoate (10.0, 9.58, and 12.2 μg/cm(2)) against D. farinae, D. pteronyssinus, and T. putrescentiae. In structure-activity relationships, the acaricidal activities of apiol derivatives could be related to allyl (-C(3)H(5)) and methoxy (-OCH(3)) functional groups. Furthermore, apiol and its derivatives could be useful for natural acaricides against these three mite species.

Standardization of Acaricidal Bioassays for Developing Natural Acaricides against Three Mite Species (Arachnida: Acari)

To establish a system of effective bioassays for natural acaricides against three mite species, influences of bioassay system, solvent drying time, and leaf-dipping time were investigated. Among the tested organic solvents, including diethyl ether, hexane, and acetone, acetone was found to be the most suitable for developing natural acaricides, whereas diethyl ether and hexane were not suitable. Solvent drying and leaf-dipping times of acetone were suitable at 10 min and 60 s, respectively. Application method of spraying (direct contact) bioassay was more effective than other methods. These results could be used in the standardization of bioassay systems for natural acaricides.

Comparative Effectiveness of Some Acaricides used to ControlVarroa destructor(Mesostigmata: Varroidae) in Algeria

In this study the effectiveness of two synthetic (Bayvarol and Apivar) and two natural acaricides (Apiguard and ApiLife Var) against Varroa destructor were evaluated with use of infested colonies of Apis mellifera intermissa, housed in Langstroth standard hives. Each acaricide was tested in five hives, and one group of five hives was left untreated as the control. All acaricides significantly reduced the levels of varroa mite infestation on adult honeybees and worker brood, but the efficacy was higher for Apiguard (93–97 %) and ApiLife Var (94–98 %) compared to Bayvarol (85–90 %) and Apivar (82–88 %). Overall, the data indicated that essential oils like Apiguard and ApiLife Var can be recommended in the control of V. destructor, while synthetic varroacides like Bayvarol and Apivar should be minimized due to increased mite resistance for these products.

Acaricidal activity of triketone analogues derived from Leptospermum scoparium oil against house‐dust and stored‐food mites

Various attempts to control the populations of house-dust and stored-food mites have been implemented using synthetic chemicals. Although effective, the repeated use of these chemicals has led to resistance owing to the mite's high reproductive potential and short life cycle. Therefore, this study aimed to develop natural acaricides using oils derived from Leptospermum scoparium JR & G Forst., which may affect the overall biological activity of a mite without adverse effects. Results were compared with those from using benzyl benzoate and N,N-diethyl-3-methylbenzamide (DEET). The LD(50) values of L. scoparium oil were 0.54, 0.67 and 1.12 microg cm(-2) against Dermatophagoides farinae (Hughes), D. pteronyssinus (Troussart) and Tyrophagus putrescentiae (Schrank) respectively. The active constituent isolated from L. scoparium was identified as leptospermone (6-isovaleryl-2,2,4,4-tetramethyl-1,3,5-cyclohexanetrione) by spectroscopic analysis. Based on the LD(50) values of leptospermone and its derivatives, the most toxic compound against D. farinae was leptospermone (0.07 microg cm(-2)), followed by 2,2,4,4,6,6-hexamethyl-1,3,5-cyclohexanetrione (1.21 microg cm(-2)), benzyl benzoate (10.03 microg cm(-2)) and DEET (37.12 microg cm(-2)). Furthermore, similar results were observed when the leptospermone and its derivatives were tested against D. pteronyssinus and T. putrescentiae. These results indicate that L. scoparium oil-derived materials, particularly leptospermone and 2,2,4,4,6,6-hexamethyl-1,3,5-cyclohexanetrione, have potential for development as new agents for the control of three species of mite.

Sensibilidade do carrapato Boophilus microplus a solventes

Os experimentos envolvendo o uso de acaricidas sintéticos ou naturais, geralmente necessitam da utilização de um solvente. Com a finalidade de verificar a sensibilidade do carrapato bovino Boophilus microplus a diferentes solventes, larvas e fêmeas ingurgitadas deste ectoparasito foram expostas a sete solventes em cinco diferentes concentrações, na ausência e presença de azeite de oliva. Os resultados mostraram que a utilização do azeite de oliva não produz resultados diferentes estatisticamente em testes de larvas com papel impregnado, fato não verificado em testes de imersão de adultos com compostos hidrofílicos. A mortalidade média causada pelos solventes foi menor nos testes com papel impregnado, aumentando nos testes de imersão de larvas e de adultos. Solventes de baixo peso molecular e pouca viscosidade como o álcool metílico e o álcool etílico, não interferiram na mortalidade média em testes biológicos de B. microplus, principalmente em concentrações inferiores a 76%.