Plantas con actividad insecticida: una alternativa natural contra mosquitos / Insecticidal activity plants: A natural alternative against mosquitoes. Current status of the topic in the America´s region

Resumen El siguiente trabajo pretende reunir la información existente con respecto la evaluación de la actividad insecticida de plantas contra mosquitos realizados en la región de las Américas en los últimos veinte años. Se utilizó Pubmed Central, SCielo regional y BioOne y se acudió a buscadores como Google y Bing. Como criterio de inclusión se introdujeron las categorías: actividad larvicida, adulticida-repelente, ovicida e inhibidora del desarrollo de aceites esenciales y extractos de plantas en condiciones de laboratorio contra mosquitos en el área de las Américas en un período desde 1995-2015. La especie de mosquito más estudiada ha sido Ae aegypti seguido de Cx. quinquefascitus, Ae. albopictus, Cx. tarsalis, Cx. pipiens, An. albimanus. El país a la vanguardia en estudios sobre esta temática es Brasil seguido de Cuba México, Estados Unidos. Estados Unidos se destaca por la evaluación de productos comerciales registrados a base de plantas con actividad repelente. En 239 plantas se evaluó la actividad larvicida. El 64 % de los artículos revisados estudia este tipo de actividad con aceites esenciales. La repelencia es el acápite más estudiado después de la actividad larvicida, dentro de los que se destacan la evaluación de formulaciones comerciales con principios activos naturales. Con escasa representación, se encuentran los estudios sobre la actividad ovicida e inhibidora del desarrollo. Más de 85 plantas se evaluaron en forma de extractos y el extracto mas evaluado fue el etanólico seguido del metanólico y el acuoso.

Abstract The following paper aims to gather the existing information regarding the evaluation of the insecticidal activity of plants against mosquitoes made in the region of the Americas in the last twenty years. Pubmed Central, SCielo regional and BioOne were used and search engines such as Google and Bing were used. As an inclusion criterion, the categories were introduced: larvicidal, adulticidal-repellent, ovicidal activity and inhibitor of the development of essential oils and extracts of plants under conditions of Laboratory in the area of the Americas in a period from 1995-2015. The most studied mosquito species was Ae aegypti followed by Cx. quinquefascitus, Ae. albopictus and Cx tarsalis, Cx. pipiens, An. albimanus. The country at the forefront in studies on this subject is Brazil followed by Cuba Mexico, United States. The United States stands out by evaluating commercially registered herbal products with repellent activity. The larvicidal activity was evaluated in 239 plants. 64% of the reviewed articles study this type of activity with essential oils. The repellency is the most studied section after the larvicidal activity, among which the evaluation of commercial formulations with natural active principles. With little representation, there are studies on ovicidal and developmental inhibitory activity. More than 85 plants have been evaluated in the form of extracts and the most evaluated extract has been ethanolic followed by methanolic and aqueous.

Essential oil of Cinnamodendron dinisii Schwanke for the control of Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae) / Óleo essencial de Cinnamodendron dinisii Schwanke para controle de Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae)

ABSTRACT The use of natural compounds is a less aggressive alternative for the control of insects in stored grains, in relation to synthetic chemical agents. Plants with insecticidal properties can be used as a source of these compounds to the direct application in pest control. In this work, the essential oil of Cinnamodendron dinisii was chemically characterized and tested regarding its insecticidal and repellent effect on the control of Sitophilus zeamais in stored grains. The essential oil was obtained by hydrodistillation and analyzed by gas chromatography–mass spectrometry (GC-MS). The insecticidal potential was evaluated through the maintenance of the insects during 24 hours in contact with several doses of the oil, in the absence of feed substrate. The Bioassays of repellency were conducted with lethal doses (LD5, LD25, LD50 and LD95) obtained from insecticidal bioassay. In order to compare the treatments, the preference index (PI) was used. The essential oil of C. dinisii had insecticidal activity against S. zeamais, causing a linear and crescent mortality with LD of 0.04, 0.17, 0.34 and 0.63 µL/cm2, respectively. The repellency ranged from 55.4% to 85.2%, using the LD values previously mentioned. The DL5 was neutral regarding repellence (PI index -0,09), but from DL25 on, the PI index was between -0.1 and -1.0, indicating repellence activity.

RESUMO O uso de compostos naturais é uma alternativa menos agressiva para o controle de insetos em grãos armazenados em relação aos agentes químicos sintéticos. Plantas com propriedades inseticidas podem ser usadas como fonte destes compostos para a aplicação direta no controle de pragas. No presente trabalho, o óleo essencial de Cinnamodendron dinisii foi caracterizado quimicamente e testado em relação ao seu efeito repelente inseticida no controle de Sitophilus zeamais em grãos armazenados. O óleo essencial foi obtido por hidrodestilação e analisado por cromatografia gasosa-espectrometria de massa (GC-MS). O potencial inseticida foi avaliado pela manutenção dos insetos durante 24 horas em contato com várias doses de óleo, na ausência de substrato alimentar. Os bioensaios de repelência foram realizados com as doses letais (DL5, DL25, DL50 e DL95) obtidas do bioensaio inseticida. Para comparar os tratamentos foi utilizado o índice de preferência (PI). O óleo essencial de C. dinisii apresentou atividade inseticida sobre S. zeamais, causando mortalidade linear e crescente com DL de 0,04, 0,17, 0,34 e 0,63 µL/cm2, respectivamente. A repelência variou entre 55,4% até 85,2%, utilizando os valores de DL acima mencionados. A DL5mostrou-se neutra em relação à repelência (índice PI -0,09), mas a partir de DL25 o índice PI foi entre -0,1 e -1,0, indicando atividade de repelência.

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.

Avaliação preliminar de óleos essenciais de plantas como repelentes para Aedes albopictus (Skuse, 1894) (Diptera: Culicidae) / Preliminary evaluation of plant essential oils as repellents against Aedes albopictus (Skuse, 1894) (Diptera: Culicidae)

Óleos essenciais de plantas têm sido formulados de forma caseira ou colocados no mercado de forma artesanal para repelir mosquitos hematófagos. O presente trabalho avaliou o possível efeito repelente de alguns excipientes normalmente usados em formulações comerciais e de óleos essenciais de nove plantas, sobre fêmeas de Aedes albopictus. Os testes foram realizados em caixas contendo mosquitos, oferecendo-se uma área definida de dedos da mão tratados ou não. Exceto pelo creme Lanatte e os géis de carbopol, as substâncias excipientes avaliadas mostraram ação repelente. Apenas os óleos provenientes de citronela (5 e 10 por cento) resultaram em repelência expressiva, com índices médiosde proteção acimade 98 por cento. Os resultados indicam que a metodologia empregada é adequada para a avaliação preliminar de produtos com potencial para a repelência de mosquitos.

Plant essential oils have been domestically formulated or marketed as handcraft products to repel hematophagous mosquitoes. This work evaluated the possible repellent effect of both excipients normally used in commercial formulations and essential oils from nine plants against Aedes albopictus females. The assays were carried out in boxes containing mosquitoes, where a defined area of treated or non-treated fingers was offered. Except for Lanatte cream and carbopol gels, the evaluated excipients had repellent action. Only the oils from citronella (5 and 10 percent) presented expressive repellent action, with mean protection indexes above 98 percent. The results indicate that the used methodology is appropriate for the preliminary evaluation of products with potential to repel mosquitoes.

Efeito do óleo essencial de Tagetes patula L. (Asteraceae) sobre Sitophilus zeamais Motschulsky (Coleoptera, Curculionidae) / Effect of essential oil of Tagetes patula L. (Asteraceae) on Sitophilus zeamais Motschulsky (Coleoptera, Curculionidae)

Resistência de pragas a inseticidas, danos ao ambiente em função da poluição do solo e de recursos hídricos vem sendo observados pelo uso de inseticidas químicos no controle de pragas em grãos armazenados. Com o intuito de minimizar estes problemas, estão sendo estudadas alternativas como o uso de inseticidas botânicos. Este trabalho foi realizado com o objetivo de avaliar o efeito do óleo essencial de Tagetes patula L. sobre, Sitophilus zeamais Motschulsky, 1855 em milho sob condições de laboratório. O óleo essencial de T. patula foi obtido através de arraste a vapor com aparelho clevenger. A caracterização química dos compostos encontrados no óleo essencial de T. patula foi realizada através de cromatografia gasosa acoplado a espectrometria de massas, sendo observados: limoneno (37,05 por cento), terpinoleno (32,61 por cento), piperitone (14,40 por cento), eofitadieno (5,91 por cento), sabineno (2,88 por cento), trans-ocimeno (2,02 por cento), beta-cariofileno (1,98 por cento), farnesol (1,84 por cento) e alfa-pineno (1,30 por cento). Os insetos utilizados nos bioensaios foram mantidos em temperatura e umidade relativa controlada. Foram avaliados os efeitos do óleo essencial de T. patula sobre o comportamento (atratividade e/ou repelência) e atividade inseticida sobre adultos de S. zeamais através de dois bioensaios. Pelos resultados pode-se observar o efeito repelente e inseticida do óleo essencial de T. patula sobre S. zeamais, na concentração de 10 µL (p<0,0001 e p=0,02) sendo portanto, eficaz no controle de adultos de S. zeamais.

Countless problems due to the use of chemical insecticides for the control of pests in stored grains have been observed. In order to minimize these problems, alternative measures have been developed, including the use of botanical insecticides. This work was carried out with the objective of evaluating the effect of the essential oil of Tagetes patula L. on, Sitophilus zeamais (Mots., 1855) in corn kernels in laboratory conditions. The T. patula essential oil was obtained through hidrodestilation with the Clevenger device. The chemical characterization of the compounds found in the essential oil of T. patula was carried by gas chromatography connected to the mass spectrometer. The compounds found were: limonene (37.05 percent), terpinolene (32.61 percent), piperitone (14.40 percent), neophitadiene (5.91 percent), sabinene (2.88 percent), trans-ocimene (2.02 percent), beta-cariphilene (1.98 percent), farnesol (1.84 percent), and alpha-pinene (1.30 percent). The insects used in the bio-test were kept under controled temperature and relative humidity environment. Two bioassays were carried out to evaluate the effect of the essential oil of T. patula on the behavior (activity/repellence) and insecticide activity on adults of S. zeamais. The results showed that this essential oil was efficient (concentration of 10 µL) to control adults of S. zeamais adults.