Actividad repelente e insecticida de cuatro aceites esenciales de plantas recolectadas en Chocó-Colombia contra Tribolium castaneum / Repellent and insecticidal activity of four essential oils from plants recolleted in Chocó-Colombia against Tribolium castaneum

This study aimed to determine the repellent and insecticidal activity of four essential oils (EOs) from plants collected in the Chocó rain forest, Colombia, against T. castaneum . Conventional hydrodistillation was used to obtain the EOs. The repellent and insecticidal activities were evaluated by the preference area and gas dispersion methods, espectively. Statistical differences (p<0.05) were determined by applying a student's t-test. EOs of Siparuna guianensis, S. conica, Piper marginatum, and Nectandra acutifolia showed excellent repellent properties as the main findings, highlighting S. conicaEO with 84% repellency (1-hµL/cm2), while P. marginatum showed to be bioactive to the dose of 500 µL/mL (72 h), inducing mortality of 100% of the exposed population. In conclusion, the results evidenced the repellent properties of the EOs evaluated against T. castaneum , which allows us to conclude that these plant species are potential natural sources producing bio-repellents that contribute to the integrated control of T. castaneum.

Se evaluaron cuatro aceites esenciales (AEs) de plantas recolectadas en la selva pluvial del Chocó, Colombia, para determinar su actividad repelente e insecticida contra T. castaneum. Los AEs fueron obtenidos por hidrodestilación convencional. Las actividades repelentes e insecticidas se evaluaron por los métodos de área de preferencia y dispersión de gas, respectivamente. Las diferencias significativas (p<0,05) fueron determinadas aplicando una prueba t de student. Los AEs de Siparuna guianensis, S. conica, Piper marginatum y Nectandra acutifolia mostraron excelentes propiedades repelentes, destacando el AE de S. conicacon un 84% de repelencia (1µL/cm2), mientras que el AE de P. marginatummostró ser bioactivo a la dosis de 500 µL/mL (72 h) al inducir la mortalidad del 100% de la población expuesta. Se concluye que estas especies de plantas son fuentes naturales potencialmente viables para la producción de biorepelentes que contribuyan en el control integrado de T. castaneum.

Repellent activity of essential oils extracted from five Artemisia species against Tribolium castaneum (Coleoptera: Tenebrionidae) / Actividad repelente de aceites esenciales extraídos de cinco especies de Artemisia contra Tribolium castaneum (Coleoptera: Tenebrionidae)

Artemisia genus (family Asteraceae) has been widely used as medicines and cosmetic. The chemical compositions of essential oils extracted from five Artemisia species (A. anethoides, A. giraldii, A. roxburghiana, A. rubripes and A. sacrorum) were analyzed and the repellent activities of five essential oils were investigated by testing percent repellency (PR) in petri dish against Tribolium castaneum. By GC-MS analysis, the common components of the five essential oils were eucalyptol (11.09%-50.05%), camphor (6.28%-33.10%), terpinen- 4-ol (2.46%-12.41%), ß-caryophyllene (0.63%-10.68%) and germacrene D (2.28%-10.01%). 3,3,6-trimethyl-1,4-heptadien-6-ol (11.72%), 2-isopropyl-5-methyl-3-cyclohexen-1-one (24.80%) and ß-farnesene (12.23%) were the characteristic compounds in essential oils of A. sacrorum, A. anethoides and A. rubripes respectively. The essential oils of five plants showed repellent activity against T. castaneum. The PR of others four essential oils were comparable with DEET expect for A. sacrorum. The results indicated that the essential oils of A. anethoides, A. giraldii, A. roxburghiana and A. rubripes had the potential to be developed as repellent for control of T. castaneum.

El género Artemisia (familia Asteraceae) ha sido ampliamente utilizado como medicamentos y cosméticos. Se analizaron las composiciones químicas de los aceites esenciales extraídos de cinco especies de Artemisia (A. anethoides, A. giraldii, A. roxburghiana, A. rubripes y A. sacrorum) y se investigaron las actividades repelentes de cinco aceites esenciales mediante la prueba de repelencia porcentual (PR) en placa de petri contra Tribolium castaneum. Por análisis GC-MS, los componentes comunes de los cinco aceites esenciales fueron eucaliptol (11,09% -50,05%), alcanfor (6,28% -33,10%), terpinen-4-ol (2,46% -12,41%), ß-cariofileno 0,63% -10,68%) y germacrén D (2,28% -10,01%). 3,3,6-trimetil-1,4-heptadien-6-ol (11,72%), 2-isopropil-5-metil-3-ciclohexen-1-ona (24,80%) y ß-farneseno (12,23%). Los compuestos característicos en los aceites esenciales de A. sacrorum, A. anethoides y A. rubripes respectivamente. Los aceites esenciales de cinco plantas mostraron actividad repelente contra T. castaneum. El PR de otros cuatro aceites esenciales eran comparables con DEET esperado para A. sacrorum. Los resultados indicaron que los aceites esenciales de A. anethoides, A. giraldii, A. roxburghiana y A. rubripes tienen el potencial de ser desarrollados como repelentes para el control de T. castaneum.

Insecticidal activity of neem oil against Gyropsylla spegazziniana (Hemiptera: Psyllidae) nymphs on Paraguay tea seedlings / Atividade inseticida de óleo de nim contra ninfas de Gyropsylla spegazziniana (Hemiptera: Psyllidae) em mudas de erva-mate

Abstract Gyropsylla spegazziniana (Paraguay tea ampul) is one of the most important pests of Paraguay tea plants, and prohibition of synthetic insecticide use for control of this pest has led to the search for alternative methods. This laboratory study aimed to compare different control strategies for G. spegazziniana, utilizing a commercial neem seed oil product. Paraguay tea seedlings were treated with neem oil solution both pre- and post-infestation with 5th instar nymphs. The systemic action of neem oil was also evaluated by treating plant soil with the neem oil solution, followed by transfer of the insects to plants 24 h post-treatment. Spray treatments were effective against the pest, especially post-infestation (80% mortality), demonstrating the potential of neem oil for control of the Paraguay tea ampul. No significant effects were observed with respect to systemic activity.

Resumo Gyropsylla spegazziniana (ampola da erva-mate) é uma das principais pragas da erva-mate, tanto em áreas de plantio como em viveiros. A proibição do uso de inseticidas para o controle de pragas da cultura tem levado à busca de alternativas. Este trabalho visou avaliar comparativamente, em laboratório, estratégias de aplicação de um produto comercial à base de óleo de nim sobre G. spegazziniana, em solução a 5%. Os testes foram realizados em mudas de erva-mate, tratadas pré e pós-infestação com ninfas de 5º instar do inseto, para avaliação de contato. Também, avaliou-se a ação sistêmica do óleo de nim, aplicando-se a solução do produto no solo da muda de erva-mate, seguido da transferência dos insetos após 24 h. Verificou-se que os tratamentos via pulverização foram eficientes contra a praga, principalmente na aplicação pós-infestação (80% de mortalidade), comprovando o potencial inseticida do óleo de nim contra a ampola-da-erva-mate em mudas. Entretanto, em relação à atividade sistêmica, não foram observados efeitos consideráveis sobre a praga.

Efectividad de repelentes comerciales disponibles contra el mosquito Aedes aegypti (L ) en Yucatán, México / Effectiveness of commercial repellents against Aedes aegypti (L ) in Yucatan, México

Resumen: Objetivo: Determinar la eficacia de repelentes comerciales disponibles en Yucatán contra el mosquito Aedes aegypti, vector del dengue, Chikungunya y Zika. Material y métodos: Se determinó el tiempo de protección con base en el protocolo WHO/CTD/WHOPES/IC y la NOM-032-SSA2-2014. Resultados: Sólo el repelente con DEET (N, N-dietil-3-metilbenzamida) al 25% cumplió con la protección recomendada. La eficacia fue directamente proporcional a la concentración del DEET; aquéllos con componentes botánicos fueron poco o nada protectores. Conclusiones: Los resultados muestran que los repelentes con DEET proveen protección contra Ae. Aegypti; los repelentes botánicos, incluyendo las pulseras impregnadas, ofrecen nula protección.

Abstract: Objective: We assessed the efficacy of commercial repellents available in Yucatan against Aedes aegypti, vector of dengue, Chikungunya and Zika. Materials and methods: Protection time was determined based on WHO/CTD/ WHOPES/IC y la NOM-032-SSA2-20I4. Results: Products with DEET (N, N-diethyl-3-methylbenzamide) at 25% met the recommended protection. Efficacy was directly proportional to the concentration of DEET; botanicals repellents resulted no protective. Conclusions: Repellents with DEET provided more protection against Ae. aegypti and botanical repellents, including impregnated wristbands, provided no protection.

Bioactividad del aceite esencial de croton trinitatis millsp colombiano / Bioactivities of essential oil from colombian croton trinitatis millsp

Los aceites esenciales son motivo de estudio debido a propiedades bioactivas, las cuales varían de acuerdo con su composición química. Los objetivos de este trabajo fueron el estudio de la composición química volátil del aceite esencial (AE) de Croton trinitatis Millsp (Euphorbiaceae) obtenido de plantas colectadas en el municipios Maria La Baja (Bolívar). Además, evaluar sus propiedades antioxidante y repelente. AEs fueron aislados mediante la técnica de hidrodestilación e identificados por cromatografía de gases acoplada a un detector de espectrometría de masas (GC-MS). Los compuestos mayoritarios encontrados en C. trinitatis fueron sesquiterpenos: cariofileno (15,3 por ciento), dihidrocurcumeno (14,5 por ciento), cis y trans calameneno (4.0 y 13.7.0 por ciento, respectivamente), ipsilon-cadina-1,4-dieno (7.4 por ciento), alaskeno (6.4 por ciento), gerrmacreno A (5.8 por ciento), biciclogermacreno (5.3 por ciento); y monoterpenos como fenchona (4.4 por ciento) y eucaliptol (1,8-cineol) (2.4 por ciento). La actividad antioxidante de los AEs se determinó por el método del radical DPPH. El porcentaje de inhibición de DPPH del aceite esencial de C. trinitatis fue del 92.2 por ciento comparado con la del ácido ascórbico (96.4 por ciento). El AE presentó la mayor actividad repelente frente al gorgojo Tribolium castaneum, a una concentración de 0.1 μL/cm2 a 2 y 4 horas de exposición (86.0 y 92.0 por ciento, respectivamente).

Essential oils are being studied because bioactive properties, which vary according to their chemical composition. The objectives of this work were to study the volatile chemical composition of essential oil (EO) from Croton trinitatis Millsp (Euphorbiaceae), obtained from plants collected in Maria la Baja (Bolívar). Also, evaluate their antioxidant and repellent properties. EOs were isolated by hydrodistillation technique and identified by gas chromatography coupled to a mass spectrometric detector (GC-MS). The major compounds found in C. trinitatis were sesquiterpens: Caryophyllene (15,3 percent), dihydrocurcumene (14,5 percent), cis and trans calamenene (4.0 y 13.7.0 percent, respectively), upsilon-cadina-1,4-diene (7.4 percent), alaskene /6.4 percent), gerrmacrene A (5.8 percent), bicyclogermacrene (5.3 percent); and monoterpens as fenchone (4.4 percent) and eucalyptol (1,8-cineol) (2.4 percent). The antioxidant activity of the EOs were determined using the method of DPPH radical. The percentage of inhibition of DPPH from C. trinitatis was 92.2 percent compared with ascorbic acid (96,4 percent). The EO from Turbaco had the highest repellent activity against Tribolium castaneum, at a concentration of 0.2 uL/cm2 at 2 and 4 hours of exposure (86.0 and 92.0 percent, respectively).

Chemical composition of the essential oil from Ageratina jocotepecana and its repellent effect on drywood termite incisitermes marginipennis / Composición química del aceite esencial de Ageratina jocotepecana y su efecto repelente en termitas de madera seca incisitermes marginipennis

Essential oils obtained from new plant species with metabolomes unexplored or poorly known are a natural resource to find molecules with deterrent (irritant) effect. The aim of this study was to evaluate the chemical composition and the termite repellent activity of the essential oils from Ageratina jocotepecana. The repellent effect was determined by the pine drywood termite Incisitermes marginipennis behavior of to sense the contact of the tunnel wall in the wooden colony in the presence of an irritant obstacle caused by essential oils. Gas chromatographic analysis of the essential oils from flower, leaf, and stem showed quantitative and qualitative differences in components. Twenty-eight volatile components were identified by their mass spectra (MS). beta-caryophyllene, carvacrol, spathulenol, and terpinen-4-ol were the four major components, of them in relation 0.1 M citronellol, the 0.1 M carvacrol was the best repellent of the termite. Essential oils from A. jocotepecana exhibited a termite repellent effect due to their major components. Additionally, more research about the termite repellent action of carvacrol is still needed.

Los aceites esenciales obtenidos de nuevas especies de plantas con metabolomas inexplorados o poco conocidos son un recurso natural para encontrar moléculas con efecto disuasivo (irritante). El propósito del estudio fue evaluar la composición química de los aceites esenciales de Ageratina jocotepecana y su actividad repelente de termitas. El efecto repelente fue determinado por el comportamiento de las termitas de la madera seca de pino Incisitermes marginipennis de sentir el contacto de la pared del túnel en la colonia de madera en la presencia de un obstáculo irritante causado por los aceites esenciales. El análisis de cromatografía de gases de los aceites esenciales de flores, hojas y tallo mostró diferencias cuantitativas y cualitativas en componentes. Veintiocho componentes volátiles fueron identificados por sus espectros de masas (MS). beta-cariofileno, carvacrol, spathulenol y terpinen-4-ol fueron los cuatro componentes mayoritarios, de ellos en relación con 0,1 M citronelol el control positivo, el carvacrol 0,1 M fue el mejor repelente de la termita. Además, más investigación sobre la acción repelente de termitas de carvacrol se necesita realizar.

Repellent activity of Glycosmis plant extracts against two stored product insects / Actividad repelente de extractos de plantas Glycosmis contra dos insectos de productos almacenados

In the present study, the repellent activities of the leaf and/or stem crude extracts of Glycosmis lucida Wall. ex Huang, G. craibii var. glabra, G. craibii Tanaka, G. oligantha Huang, G. pentaphylla (Retz) Correa. and G. esquirolii (Levl.) Tanaka were analyzed by using assays on petri dishes against Tribolium castaneum and Liposcelis bostrychophila. The leaf and stem extracts of G. lucida, G. craibii var. glabra, G. craibii Tanaka, G. oligantha and G. esquirolii possessed significant repellent activities against T. castaneum, the same level repellent with the positive control, DEET. However, the extracts of G. pentaphylla, no repellency but some insect attractant was observed. Moreover, they also showed repellent activities against L. bostrychophila. These results indicate that extracts from G. lucida and G. oligantha leaf could be a source of novel repellent against insects.

En el presente estudio, las actividades repelentes de la hoja y/o tronco de los extractos crudos de Glycosmis lucida Wall. ex Huang, G. craibii var. glabra, G. craibii Tanaka, G. oligantha Huang, G. pentaphylla (Retz) Correa y G. esquirolii (Levl.) Tanaka se analizaron mediante el uso de ensayos en placas de Petri contra Tribolium castaneum y Liposcelis bostrychophila. Los extractos de las hojas y tallo de G. lucida, G. craibii var. glabra, G. craibii Tanaka, G. oligantha y G. esquirolii poseían actividades repelentes significativas contra T. castaneum, el mismo nivel repelente del control positivo, el DEET. Sin embargo, los extractos de G. pentaphylla, no se observó la repelencia pero sí actividad atrayente de insectos. Por otra parte, también se mostraron las actividades repelentes contra L. bostrychophila. Estos resultados indican que los extractos de hojas de G. lucida y G. oligantha podrían ser una fuente de repelente contra los insectos.

Insecticidal and repellent activity of the essential oil of Cinnamomum camphora var. linaloolifera Y. Fujita (Ho-Sho) and Cinnamomum camphora (L. ) J Presl. var. hosyo (Hon-Sho) on Sitophilus zeamaisMots. (Coleoptera, Curculionedae) / Atividade inseticida e repelente do óleo essencial de Cinnamomum camphora var. linalooliferaY. Fujita (Ho-Sho) e Cinnamomum camphora (L. ) J Presl. var. hosyo (Hon-Sho) sobre Sitophilus zeamais Mots. (Coleoptera, Curculionedae).

ABSTRACT: The aim of this work was to evaluate the insecticidal and repellency activity of the essential oil of Cinnamomum camphora var. linaloolifera Y. Fujita (Ho-Sho) and Cinnamomum camphora (L.) J Presl.var. hosyo (Hon-Sho), against the Sitophilus zeamais in maize grains. The essential oils were obtained by hydrodistillation and analyzed by GC-MS.The insecticidal activity was determined by the toxicity of different concentrations of essential oils during 24 hours of contact with the insects, in the absence of feed substrate. The Bioassays of repellency were conducted with lethal doses (LD50,LD25,and LD12.5) obtained from insecticidal bioassay. In order to compare the treatments the preference index (PI) was employed. The analysis of the essential oils of Cinnamomum camphora leaves indicated 68% of camphor and 9% of linalool for the variation Hon-Sho and 95% of linalool to the variation Ho-Sho. The variation Ho-Sho presented greatest insecticidal activity than the variation Hon-Sho against the Sitophilus zeamais, with LD50 of 0.35 µL/cm2, whereas in the variation Hon-Sho the ratewas 0.48 µL/cm2. However, considering only the concentrations of linalool and camphor of Ho-Sho and Hon-Sho, the lethal doses' evaluation of these compounds were similar. The values of the preference index ranged from -0.3 to -0.8 for thevariation Ho-Sho and -0.2 to -0.7 for the variation Hon-Sho. The essential oils evaluated in this work showed repellent activity against Sitophiluszeamais in vitro and in trials performed in mini-silos

RESUMO: Atividade inseticida e repelente do óleo essencial de Cinnamomum camphora var. linaloolifera Y. Fujita (Ho-Sho) e Cinnamomum camphora (L.) J Presl. var. hosyo (Hon-Sho) sobre Sitophilus zeamais Mots. (Coleoptera, Curculionedae). O objetivo deste trabalho foi avaliar a atividade inseticida e de repelência dos óleos essenciais de Cinnamomum camphora var. linaloolifera Y. Fujita (Ho-Sho) e Cinnamomum camphora (L.) J Presl. var. hosyo (Hon-Sho) contra Sitophilus zeamais em grãos de milho. Os óleos essenciais foram obtidos por hidrodestilação e analisados por CG-EM. A atividade inseticida foi determinada pela toxicidade de diferentes concentrações dos óleos essenciais durante 24 horas de contato com os insetos, na ausência de substrato alimentar. Os bioensaios de repelência foram realizados com as doses letais (DL50, DL25, e DL12,5) obtidas do bioensaio inseticida. Para comparar os tratamentos foi utilizado o índice de preferência (PI). A análise de óleos essenciais de folhas de Cinnamomum camphora indicou a presença de 68% de cânfora e 9% de linalol na var. Hon-Sho e de 95% de linalol na var. Ho-Sho. A var. Ho-Sho apresentou maior toxicidade que var. Hon-Sho contra Sitophilus zeamais, com DL50 de 0,35 µL/cm2,enquanto que na var. Hon-Sho foi de 0,48 µL/cm2. No entanto, considerando apenas as concentrações de linalol e cânfora de Ho-Sho e Hon-Sho, a avaliação das doses letais destes compostos foram semelhantes. Os valores do índice de preferência variaram de -0,3 a -0,8 para a var. Ho-Sho e -0,2 para -0,7 para a var. Hon-Sho. Os óleos essenciais avaliados neste trabalho apresentaram atividade repelente contra Sitophilus zeamais in vitro e em experimentos realizados em mini-silos

Pesticidal and pest repellency activities of rhizomes of Drynaria quercifolia (J. Smith) against Tribolium castaneum (Herbst)

BACKGROUND: Tribolium castaneum (Herbst) is a harmful pest of stored grain and flour-based products in tropical and subtropical region. In the present study, rhizome of Drynaria quercifolia (J. Smith) was evaluated for pesticidal and pest repellency activities against T. castaneum, using surface film method and filter paper disc method, respectively. In addition, activity of the isolated compound 3,4-dihydroxybenzoic acid was evaluated against the pest. RESULTS: Chloroform soluble fraction of ethanol extract of rhizome of D. quercifolia showed significant pesticidal activity at doses 0.88 to 1.77 mg/cm² and significant pest repellency activity at doses 0.94 to 0.23 mg/cm². No pesticidal and pest repellency activity was found for petroleum ether, ethyl acetate and methanol soluble fractions of ethanol extract as well as for 3,4-dihydroxybenzoic acid. CONCLUSION: Considering our findings it can be concluded that chloroform soluble fraction of rhizome of D. quercifoliais useful in controlling T. castaneum of stored grain and flour-based products.

Pesticidal and pest repellency activities of a plant derived triterpenoid 2α, 3ß, 21ß, 23, 28-penta hydroxyl 12-oleanene against Tribolium castaneum

BACKGROUND: Tribolium castaneum (Herbst) is a major pest of stored grain-based products, and cause severe damage to cereal grains throughout the world. The present investigation was aimed to determine the pesticidal and pest repellent activities of 2α,3ß,21ß,23,28-penta hydroxyl 12-oleanene against T. castaneum. The compound 2α,3ß,21ß,23,28-penta hydroxyl 12-oleanene is a triterpenoid which was isolated from the roots of Laportea crenulata Gaud. Surface film technique was used for pesticidal screening, whereas, pest repellency property of the triterpenoid was determined by filter paper disc method. RESULTS: At 24 hours of exposure duration, significant mortality records (80% and 86%) were observed at doses 0.88 and 1.77 mg/cm². No significant change in mortality records was observed when duration of exposure was increased up to 48 hours. The triterpenoid showed significant repellency activity at doses 0.47 and 0.94 mg/cm². CONCLUSION: These data suggest that the triterpenoid 2α,3ß,21ß,23,28-penta hydroxyl 12-oleanene possess both pesticidal and pest repellency activities against T. castaneum and can be used in controlling the pest of grain-based products.

Actividad repelente de aceites esenciales contra las picaduras de Lutzomyia migonei (Diptera: Psychodidae)

Repellent activity of plant essential oils against bites of Lutzomyia migonei (Diptera: Psychodidae). Natural repellents from plant extracts have demonstrated good efficacy against bites of some insect species. The present study evaluated the repellent effect of essential oils extracted from 8 plants species against bites of Lutzomyia migonei, the Leishmania vector. The essential oils were extracted by steam destillation in Clevenger chamber, from the following plants: Hyptis suaveolens, Pimenta racemosa, Piper marginatum, Monticalia imbricatifolia, Pseudognaphalium caeruleocanum, Espeletia shultzii, Plecthranthus amboinicus and Cinnamomun zeylanicum. Repellency tests were performed under laboratory conditions by the human hand method in cage assays, using female colonies of L. migonei. The more effective oils were tested at variable concentrations on different volunteers. The protection percentage and time were calculated. The results showed what oils of P. caeruleocanum and C. zeylanicum were the most effective. Although P. amboinicus oil also had repellent effect showed an irritant effect. The oils P. marginatum, H. suaveolens and P. racemosa showed no repellent effect, while the rest of oil extracts showed significant repellency in variable degrees. P. caeruleocanum and C. zeylanicum oils provided the 95% protection against bites of L. migonei for 3h. The P. caeruleocanum oil showed the greatest protection time, with a mean over 4h and 3h at concentrations of 50% and 10% respectively. The results suggest that the P. caeruleocanum oil could represent a potential natural repellent against Leishmania vectors. Rev. Biol. Trop. 58 (4): 1549-1560. Epub 2010 December 01.

Los repelentes naturales de extractos de plantas han mostrado eficacia contra diferentes especies de insectos. El presente estudio evaluó la acción repelente de aceites esenciales extraídos de ocho especies de plantas contra las picaduras de Lutzomyia migonei, vector de Leishmania. Los aceites esenciales se obtuvieron por hidrodestilación, utilizando una trampa de Clevenger, a partir de Hyptis suaveolens, Pimenta racemosa, Piper marginatum, Monticalia imbricatifolia, Pseudognaphalium caeruleocanum, Espeletia shultzii, Plectranthus amboinicus y Cinnamomun zeylanicum. Los ensayos de repelencia se realizaron sobre humanos en condiciones de laboratorio, frente a hembras de L. migonei provenientes de colonia, utilizando el método de la mano en la jaula. Los aceites con efecto repelente también se ensayaron con distintos voluntarios y concentraciones. Se determinó el porcentaje de protección y el tiempo de protección. Los resultados revelaron que el aceite de P. caeruleocanum y C. zeylanicum fueron los más efectivos. El aceite de P. amboinicus presentó efecto de repelencia satisfactorio, sin embargo, ocasionó picazón y toxicidad en la piel. Los aceites de P. marginatum, H. suaveolens y P. racemosa no evidenciaron efecto repelente; el resto de los aceites presentaron repelencia significativa en grado variable. Los aceites de P. caeruleocanum y C. zeylanicum mostraron un 95% de protección de 3h contra las picaduras de L. migonei. El aceite de P. caeruleocanum presentó el mayor tiempo de protección, de más de 4h y de 2h en concentraciones de 50% y 10%, respectivamente. Los resultados sugieren que el aceite P. caeruleocanum podría ser un potencial candidato como repelente natural contra la picadura de dípteros posibles transmisores de Leishmania.

Redução da sobrevivência da broca-do-café, Hypothenemus hampei (Ferrari) (Coleoptera: Scolytidae), e do seu ataque aos frutos de café pela pulverização com nim em laboratório / Reduced survival and infestation of coffee borer, Hypothenemus hampei (Ferrari) (Coleoptera: Scolytidae), on coffee fruits, in response to neem sprays in laboratory

Aqueous solutions of neem oil and aqueous extracts of neem seeds and leaves were sprayed on coffee fruits for laboratory evaluation of their efficiency in reducing infestation of the coffee borer, Hypothenemus hampei (Ferrari), in multi-choice preference assays in laboratory. Neem oil and extracts reduced infestation of fruits in a dose-dependent manner, acting as a repellent. At 0.5 percent, 1 percent and 1.5 percent, the oil reduced fruit infestation by 30.2 percent, 42.5 percent (P > 0.05), and 58.6 percent (P < 0.05), respectively, as compared with the control. Seed extracts at 1 percent, 2 percent and 4 percent (w/v) reduced infestation by 30.9 percent, 38.3 percent (P > 0.05) and 70.2 percent (P < 0.05), respectively; seed extracts at 0.15 percent, 1.5 percent and 15 percent (w/v) reduced fruit infestation by 16.5 percent, 38.5 percent (P > 0.05) and 56.9 percent (P < 0.05), respectively. Spraying the emulsifiable oil at 1 percent on coffee fruits and adult borers was compared with spraying on fruits or adults only. Adult-only spraying caused low mortality (P > 0.05) and low reduction on the number of damaged fruits (P > 0.05). Fruit-only spraying significantly reduced insect survival rates and the number of damaged fruits (P < 0.05). However, spraying on adults and fruits caused the greatest reduction in adult survival (55.6 percent; P < 0.05) and in fruit infestation (78.7 percent; P < 0.05), probably due to insect mortality and neem oil repellence acting together.

Alternative control of Tetranychus evansi Baker & Pritchard (Acari: Tetranychidae) on tomato plants grown in greenhouses

Tetranychus evansi Baker & Pritchard is an important pest of solanaceous plants, including tomatoes. This mite is characterized by a high reproductive rate, which leads to high population growth in a short period of time causing important economic damage. Control of T. evansi is mainly through synthetic acaricides. In searching for environmentally friendly control measures, we evaluated the efficiency of alternative products to control T. evansi on tomato plants under greenhouse conditions. The products tested were lime sulphur and neem based products. We first estimated the lethal concentration (LC) and instantaneous rate of increase (r i) of T. evansi exposed to different product concentrations in laboratory conditions, and later tested the efficacy of LC95 and the concentrations that restrained mite population growth (r i = 0) in greenhouse conditions. The following treatments were repeated three times: NeemPro (81.0 and 71.6 mg a.i./l), Natuneem (31.1 and 20.4 mg ai/l), Organic Neem (39.1 and 30.4 mg a.i./l), lime sulphur (1.0 and 0.6 percent) and water (control). For all products, control provided by LC95 was higher than provided for lower concentrations (r i = 0) one day after spraying. However, after five days, for both concentrations, the percentage of T. evansi population reduction was superior to 95 percent and increased over time. Only plants sprayed with Natuneem (31.1 mg a.i./l) showed symptoms of phytotoxicity. Lime sulphur and neem based products, applied in appropriate concentrations and formulations, bear out as a viable alternative to control T. evansi on tomato plants.

Adulticidal activity of essential oil of Lantana camara leaves against mosquitoes.

Background & objectives: Development of insect resistance to synthetic pesticides, high operational cost and environmental pollution have created the need for developing alternative approaches to control vector-borne diseases. In the present study we have investigated the insecticidal activity of essential oil isolated from the leaves of Lantana camara against mosquito vectors. Methods: Essential oil was isolated from the leaves of L. camara using hydro-distillation method. Bioassay test was carried out by WHO method for determination of adulticidal activity against mosquitoes. Different compounds were identified by gas chromatography-mass spectrometry analysis. Results: LD50 values of the oil were 0.06, 0.05, 0.05, 0.05 and 0.06 mg/cm2 while LD90 values were 0.10, 0.10, 0.09, 0.09 and 0.10 mg/cm2 against Ae. aegypti, Cx. quinquefasciatus, An. culicifacies, An. fluvialitis and An. stephensi respectively. KDT50 of the oil were 20, 18, 15, 12, and 14 min and KDT90 values were 35, 28 25, 18, 23 min against Ae. aegypti, Cx. quinquefasciatus, An. culicifacies, An. fluviatilis and An. stephensi, respectively on 0.208 mg/cm2 impregnated paper. Studies on persistence of essential oil of L. camara on impregnated paper revealed that it has more adulticidal activity for longer period at low storage temperature. Gas chromatographic-mass spectrometric analysis of essential oil showed 45 peaks. Caryophyllene (16.37%), eucalyptol (10.75%), α-humelene (8.22%) and germacrene (7.41%) were present in major amounts and contributed 42.75 per cent of the total constituents. Interpretation &conclusion: Essential oil from the leaves of L. camara possesses adulticidal activity against different mosquito species that could be utilized for development of oil-based insecticide as supplementary to synthetic insecticides.

Repellent activity of DEET against Amblyomma cajennense (Acari: Ixodidae) nymphs submitted to different laboratory bioassays / Atividade repelente do DEET contra ninfas de Amblyomma cajennense (Acari: Ixodidae) em bioensaio laboratorial

This study was developed to evaluate the repellent activity of N,N-diethyl-3-methylbenzamide (DEET) against Amblyomma cajennense nymphs. Two repellent bioassays were compared and the effective concentration and repellent time were calculated. The fingertip test was accomplished to evaluate in vivo four concentrations of the compound (0.200; 0.100; 0.050 and 0.025 mg.cm-2) and the filter-paper bioassay to evaluate in vitro the two highest concentrations. The compound provided repellence higher than 90 percent in all concentrations and at least 95 percent repellency in the highest concentration over 5 hours. The effective concentration against 50 percent of tested nymphs (EC50) was 0.006 mg.cm-2 and the EC99 was 0.036 mg.cm-2. Those concentrations were lower than the ones obtained against other tick species, denoting the effectiveness of DEET against A. cajennense. The repellency time against 50 percent of the ticks (RT50) was 4.8 hours and the RT90 was 2.7 hours. Both bioassays were adequate to evaluate A. cajennense repellency and provided similar results; however the in vivo test is more appropriate to estimate the effective concentration and repellency time.

Este estudo foi conduzido com o objetivo de avaliar a atividade repelente do N,N-diethyl-3-methylbenzamide (DEET) sobre ninfas de Amblyomma cajennense. Dois bioensaios para a avaliação de repelência foram comparados e cálculos da concentração eficaz e do tempo de repelência foram realizados. Foram empregados o bioensaio da ponta do dedo, para avaliação in vivo de quatro concentações do químico (0,200; 0,100; 0,050 e 0,025 mg.cm-2) e o bioensaio do papel filtro, para a avaliação in vitro das duas concentrações mais altas. O composto conferiu mais de 90 por cento de repelência em todas as concentrações utilizadas e 95 por cento de repelência por mais de cinco horas na maior concentração. A concentração do composto efetiva contra 50 por cento das ninfas testadas (CE50) foi de 0,006 mg.cm-2 e a CE99 foi de 0,036 mg.cm-2. Estas concentrações são mais baixas do que as observadas em outras espécies de carrapatos, denotando a efetividade do princípio contra A. cajennense. O tempo de repelência de 50 por cento dos carrapatos (TR50) foi de 4,8 horas e o TR90 de 2,7 horas. Os dois bioensaios avaliados permitiram a observação de percentuais de repelência igualmente altos e se mostraram adequados para tal avaliação, sendo que o teste in vivo é mais indicado para cálculo da concentração eficaz e da duração da repelência.

Respuesta de Anopheles albimanus a compuestos volátiles de casas del sur de Chiapas, México / Behavioral response of Anopheles albimanus to volatile compounds collected inside houses from the south of Chiapas, Mexico

OBJETIVO: Determinar el efecto de los compuestos volátiles en las casas sobre la respuesta conductual del vector del paludismo Anopheles albimanus. MATERIAL Y MÉTODOS: El estudio se realizó en enero de 2006 en el ejido Nueva Independencia, municipio de Suchiate, Chiapas. Se colectaron compuestos volátiles dentro de casas y los extractos se probaron sobre hembras sin alimentar en un olfatómetro en "Y". Los extractos se analizaron mediante cromatografía de gases-espectrometría de masas (CG-EM). RESULTADOS: Se obtuvieron 28 extractos, 12 presentaron respuesta de atracción y dos de repelencia. Los análisis por CG-EM indicaron variación en la presencia de compuestos volátiles y no se vincularon con compuestos específicos indicativos de algún efecto. CONCLUSIONES: Los volátiles en casas presentaron efecto de atracción y repelencia para An. albimanus. No se reconoció un patrón definido en cuanto a la presencia de compuestos químicos característicos y la respuesta obtenida.

OBJECTIVE: To determine effects of volatile compounds in homes on the behavioral response of Anopheles albimanus. MATERIAL AND METHODS: The study was conducted in January 2006, in the village of Nueva Independencia village, Suchiate, Chiapas. Volatile compounds were collected inside homes and the extracts were tested on unfed females in a Y-olfactometer. Extracts were analyzed in a gas chromatography-mass spectrometry system (GC-MS). RESULTS: Twenty eight extracts were obtained, twelve presented attraction and two repellency responses. GC-MS analyses of the extracts indicated variation in the volatile compound present in the extracts, but could not associated specific compounds with any particular effect. CONCLUSIONS: Within homes, volatiles presented attraction and repellency responses to An. albimanus. A definate pattern concerning the presence of a characteristic chemical compound and the observed response was not found.

Control of mosquito vectors of tropical infectious diseases: (2) pyrethroid susceptibility of Aedes aegypti ( l) collected from different sites in Thailand.

Four strains (SS, BS, A and B) of Aedes aegypti collected from different sites in Bangkok and at different times were examined for their pyrethroid susceptibility. Mosquito coils containing dl, d-T80-allethrin, d, d-T-prallethrin and methoxymethyl-tetrafluorobenzyl tetramethyl-cyclopropanecarboxylate (K-3050) with or without a synergist were tested by the 25 m3 semi-field test method. One strain (SS) was the most susceptible with KT50 values of about < 30 minutes for all mosquito coils, while the other three strains (BS, A and B) were found to be around 10 to 20 times more tolerant to pyrethroids than the SS strain. A similar tendency for the pyrethroid susceptibility of the four strains was obtained with tests by topical application method. In field efficacy tests, mosquito coils with d, d-T-prallethrin 0.20% plus N-(2-ethylhexyl)bicycle-[2,2,1]- hept-5- ene-2,3-dicarboxyimide as a synergist exhibited a repellent effect of about 85%, while those with K-3050 0.10% plus the synergist exhibited a greater repellent effect of about 90%. In contrast, the repellent effect of commercial dl, d-T80-allethrin 0.20% coils was as low as about 50%. The d, d-T-prallethrin and K-3050 coils with the synergist were confirmed to be highly effective in repelling Ae. aegypti.

The effect of essential oils of sweet fennel and pignut on mortality and learning in africanized honeybees (Apis mellifera L.) (Hymenoptera: Apidae)

It was recently discovered that exposure to small concentrations of the essential oils of sweet fennel (Foeniculum vulgare Mill) or pignut [Hyptis suaveolens (L.) Poit] can be used to control aphids. What is not known is whether these oils also influence honeybee behavior. Experiments using both harnessed and free-flying foragers at concentrations used to control aphids showed that bees readily associated the odors with a reward, discriminated between them, and were not repelled. Honeybees, however, would not consume the oils when mixed with sucrose to create an unconditioned stimulus. An experiment in which harnessed bees consumed various concentrations showed that concentrations greater than 50 percent were detrimental. The experiments reported here provide further evidence supporting the use of conditioning techniques to evaluate the use of essential oils on honey bee behavior.

Recentemente foi descoberto que pequenas concentrações de óleos essenciais de erva-doce (Foeniculum vulgare Mill) ou alfazema [Hyptis suaveolens (L.) Poit] podem ser usadas para controlar pulgões. O que não se sabe é se esses óleos também podem influenciar o comportamento de abelhas melíferas. Experimentos utilizando abelhas encapsuladas ou livres, em diferentes concentrações usadas para controlar pulgões, mostraram que as abelhas rapidamente associaram o odor a um estímulo aprendendo a discriminá-lo, e não foram repelidas pelo mesmo. No entanto, as abelhas melíferas não consumiriam os óleos quando misturados à sacarose para criar um estímulo incondicional. Em um experimento, em que abelhas encapsuladas foram submetidas a várias concentrações dos óleos essenciais, concentrações maiores que 50 por cento foram prejudiciais às abelhas. Os experimentos relatados aqui reforçam a validade do uso de técnicas de condicionamento para avaliar a ação de óleos essenciais no comportamento das abelhas melíferas.

Repellency of essential oils extracted from plants in Thailand against four mosquito vectors (Diptera: Culicidae) and oviposition deterrent effects against Aedes aegypti (Diptera: Culicidae).

In this study we evaluated and reported repellent effects of essential oils from Thai plants against 4 mosquito vectors: Aedes aegypti, Ae. albopictus, Anopheles. dirus and Culex quinquefasciatus under laboratory conditions using human volunteers. The essential oils were extracted from 18 plant species, belonging to 11 families, and the oils were then prepared as 10% solution in absolute ethanol with additives. Two chemical repellents, deet and IR3535, were also prepared in the same formulation as the essential oil repellents and tested for repellency as controls. The essential oils were also evaluated for oviposition deterrent effects against Ae. aegypti under laboratory conditions. The results show night-biting mosquitoes (An. dirus and Cx. quinquefasciatus) and Ae. albopictus were more sensitive to all the essential oils (repellency 4.5 - 8 hours) than was Ae. aegypti (repellency 0.3 - 2.8 hours), whereas deet and IR3535 provided excellent repellency against all four mosquito species (repellency 6.7- 8 hours). All essential oils exhibited oviposition deterrent activity against Ae. aegypti with various degrees of repellency ranging from 16.6 to 94.7%, whereas deet and IR3535 had no repellency. The present study demonstrates the potential for using essential oils as mosquito repellents and oviposition deterrents. These findings may lead to new and more effective strategies for protection from and control of mosquitoes.

The fumigant and repellent activity of aliphatic lactones against Pediculus humanus capitis (Anoplura: Pediculidae)

New alternative insecticides are necessary for the chemical control of head lice. In this study the fumigant knockdown time 50 percent (KT50) and repellency index (RI) of three aliphatic lactones was compared with two essential oils and DDVP, against permethrin-resistance Pediculus humanus capitis from Argentina. In the fumigant assay, none of the lactones were effective compared to the highest activity of eucalyptus (KT50 15.53 m). In the repellency test, the three lactones were equally or more effective (RI ranging from 60.50 to 76.68) than the positive control (piperonal). These lactones are promising as head lice repellents.