Insecticidal activity, Chemical Constituents of Trachyspermum ammi, Withania coagulans and Murraya koenigii ethanloic extracts against Bemisia tabaci / Atividade inseticida, constituintes químicos de extratos etanloicos de Trachyspermum ammi, Withania coagulans e Murraya koenigii contra Bemisia tabaci

Whitefly is one of the most widespread agricultural pests in the world. Essential oils might be used to control this insect in an environmentally responsible way. The fumigant, repellent, and anti-oviposition activity of ethanol-extracted essential oils of Trachyspermum ammi, Withania coagulans, and Murraya koenigii against Bemisia tabaci was investigated in this study. In the experiment, three essential oil concentrations (2.5 mg/mL, 5 mg/mL, and 10 mg/mL) were used. Trachyspermum ammi had the highest percentage of whitefly death in laboratory experiments due to its fumigant toxicity; the same tendency was found in contact toxicity and repellent effect. Mortality percent rises as the concentration of essential oil increases with bioassay time. As the concentration of essential oil grows with bioassay time, so does the mortality rate. The most adult whiteflies escaped from the treated plants' greenhouse due to the highest essential oil concentration. The greatest repellency was found with Trachyspermum ammi essential oil at 10 mg/mL. The essential oil had the greatest anti-oviposition efficacy against whiteflies. Trachyspermum ammi possessed the most potent anti-oviposition deterrent, followed by Withania coagulans in second place. Murraya koenigii finished third with moderate anti-oviposition, which affects the number of eggs produced in comparison to the control. As a consequence, these three oils might be used as an effective and environmentally acceptable bio-insecticide to control B. tabaci.

A mosca-branca é uma das pragas agrícolas mais difundidas no mundo. Os óleos essenciais podem ser usados ​​para controlar esse inseto de forma ambientalmente responsável. A atividade fumigante, repelente e antioviposição de óleos essenciais extraídos com etanol de Trachyspermum ammi, Withania coagulans e Murraya koenigii contra Bemisia tabaci foi investigada neste estudo. No experimento, foram utilizadas três concentrações de óleo essencial (2,5 mg/mL, 5 mg/mL e 10 mg/mL). Trachyspermum ammi teve a maior porcentagem de morte de mosca-branca em experimentos de laboratório devido à sua toxicidade fumigante; a mesma tendência foi encontrada na toxicidade de contato e efeito repelente. A porcentagem de mortalidade aumenta à medida que a concentração de óleo essencial aumenta com o tempo do bioensaio. À medida que a concentração de óleo essencial cresce com o tempo de bioensaio, o mesmo acontece com a taxa de mortalidade. A maioria das moscas-brancas adultas escapou da estufa das plantas tratadas devido à maior concentração de óleo essencial. A maior repelência foi encontrada com óleo essencial de Trachyspermum ammi a 10 mg/mL. O óleo essencial apresentou a maior eficácia antioviposição contra moscas-brancas. Trachyspermum ammi teve o mais potente impedimento antioviposição, seguido por Withania coagulans em segundo lugar. Murraya koenigii terminou em terceiro com antioviposição moderada, o que afeta o número de ovos produzidos em relação ao controle. Como consequência, esses três óleos podem ser usados ​​como um bioinseticida eficaz e ambientalmente aceitável para controlar B. tabaci.

Lower dose of plant substance more effective in repelling Rhyzopertha dominica F . (Coleoptera, Bostrichidae) and Sitophilus granarius L. (Coleoptera, Dryophthoridae).

INTRODUCTION AND OBJECTIVE: The study compares the effect of two concentrations (0.1% and 1%) of plant material on repelling two dangerous stored pests - Rhyzopertha dominica F. and Sitophilus granarius L. Both species were treated with the essential oils of Foeniculum vulgare Mill., Carum carvi L., Mentha pulegium L., and Cananga odorata (Lam.) Hook.f. & Thomson, as well as the chemicals contained in these oils: anethole, L-carvone, pulegone and thymoquinone. MATERIAL AND METHODS: Laboratory tests were carried out at 29±1 °C with 60±5% relative humidity (RH). Repellence of insects were noted after 1, 2, 3, 4, 5, 24 and 48 h. RESULTS: A lower dose of essential oils and some of the tested compounds caused a stronger repellence in the specified species of beetles. In the case of R. dominica, the concentration of 0.1% pulegone and L-carvone had the greatest repellent effect. Differences in the repellence of R. dominica were found between the concentrations of 0.1%-1% among all the tested substances in each time interval. This difference ranged from 5.0%-52.92%. All substances used in the tests had a strong repellent effect on S. granarius (30%-100%). There were differences in the repellency of S. granarius between 0.1%-1% concentration in most of the tested substances in each time interval, but they were not as large as for R. dominica.. CONCLUSIONS: The most interesting results were obtained concerning the relationship: the lower tested substance concentration caused a much stronger repellent effect of R. dominica and S. granarius..

Volatile Organic Compounds from Cassava Plants Confer Resistance to the Whitefly Aleurothrixus aepim (Goeldi, 1886).

Cassava is an essential tuber crop used to produce food, feed, and beverages. Whitefly pests, including Aleurothrixus aepim (Goeldi, 1886) (Hemiptera: Aleyrodidae), significantly affect cassava-based agroecosystems. Plant odours have been described as potential pest management tools, and the cassava clone M Ecuador 72 has been used by breeders as an essential source of resistance. In this study, we analysed and compared the volatile compounds released by this resistant clone and a susceptible genotype, BRS Jari. Constitutive odours were collected from young plants and analysed using gas chromatography-mass spectrometry combined with chemometric tools. The resistant genotype released numerous compounds with previously described biological activity and substantial amounts of the monoterpene (E)-ß-ocimene. Whiteflies showed non-preferential behaviour when exposed to volatiles from the resistant genotype but not the susceptible genotype. Furthermore, pure ocimene caused non-preferential behaviour in whiteflies, indicating a role for this compound in repellence. This report provides an example of the intraspecific variation in odour emissions from cassava plants alongside information on odorants that repel whiteflies; these data can be used to devise whitefly management strategies. A better understanding of the genetic variability in cassava odour constituents and emissions under field conditions may accelerate the development of more resistant cassava varieties.

Lethal and Sublethal Effects of Annona spp. Derivatives on Bemisia tabaci MEAM 1 (Hemiptera: Aleyrodidae) in Tomato.

The whitefly Bemisia tabaci(Gennadius) MEAM 1 is one of the main insect species that colonize tomato plants and cause direct and indirect damage. The use of botanical derivatives may be a valuable method of insect control to reduce the inappropriate use of synthetic insecticides on crops. In this study, we evaluated the bioactivity of ethanolic extracts prepared from Annonaceae species compared to that of the commercial insecticides based on acetogenins (Anosom® 1 EC, anonine 10,000 mg L-1) and thiamethoxam (Actara® 250 WG) on eggs, nymphs, and adults of the whitefly in tomato. Initially, the effects of the ethanolic seed extracts of Annona mucosa (Jacq.), Annona muricata L., and Annona sylvatica A.St.-Hil on adult insect behavior were evaluated. The rates of infestation and oviposition deterrence indicated the inhibitory effects of the extract of A. muricata (500 mg L-1). Then, the possible systemic effects of the extracts were evaluated; however, no effects on nymphal development or insect viability were observed. The LC50 and LC90 of the ethanolic extract of A. mucosa seeds at 500 mg L-1 (10.83 and 200.24 mg L-1, respectively) were estimated and were used in ovicidal tests and compared to positive (Actara® 250 WG and Anosom® 1 EC), and negative controls (water: acetone, 1:1 v/v). At LC90, fewer eggs (35.00%) had hatched at 13 days after application than in the other treatments. The results of this study demonstrate the potential use of botanical derivatives of Annona spp. for the management of B. tabaci MEAM 1 in tomato.

Repellence and fumigant toxicity of essential oils of Ocimum gratissimum and Ocimum kilimandscharicum on Tuta absoluta (Lepidoptera: Gelechiidae).

Tuta absoluta Meyrick originates in South America and is now one of the most important insect pests of Solanaceae in different parts of the world, including Africa. Its control has relied primarily on chemical insecticides, which are associated with negative ecological effects. In the present study, essential oils of Ocimum gratissimum and O. kilimandscharicum were tested for repellence and fumigant toxicity on the adult stages under laboratory conditions. The oil of O. gratissimum was more repellent, but its toxicity was comparable with that of O. kilimandscharicum. The major constituents of O. gratissimum were methyl eugenol (39.5%) and eugenol (29.7%). Those of O. kilimandscharicum were camphor (47.1%) and 1.8-cineole (19.3%). Eugenol (LC50 of 0.24 µl/ml, 83.3%, RI50 = 0.15) and camphor (LC50 of 0.23 µl/ml, 89.5%, RI50 = 0.13) were more toxic (at 1 µl/ml for 24 h) and repellent than the other constituents. The results show potential of the essential oils for use in integrated management of the tomato pest.

The Behavioral Response of Blattella germanica (Blattodea: Ectobiidae) Exposed to DEET Varies Throughout Its Life Cycle.

The German cockroach, Blattella germanica L., is a hemimetabolous insect pest of economical and medical importance. N,N-diethyl-3-methylbenzamide (DEET) is an insect repellent whose effect on this species has received very little attention. The objective of this work was to determine whether the behavioral response of B. germanica to DEET varies along its life cycle. DEET repellence was assessed in small, medium, and large nymphs, and in adults of both sexes, all originated from the same laboratory colony (CIPEIN). The experimental arena consisted in a piece of filter paper treated with repellent on one half (195 µg/cm2) and solvent alone on the other half. A cockroach was placed on the filter paper, and its behavior was filmed. An image analyzer was used to quantify how long the insect spent on each side of the paper. As a control, a cockroach was exposed to a piece of filter paper treated with solvent (acetone) alone. Each assay was repeated independently six times. Distribution coefficient (DC) values were calculated, a parameter that ranges between 0 (attraction) and 1 (repellence). Small nymphs were more sensitive to DEET (mean DC = 0.93). The mean DC values of the other groups varied between 0.62 (medium nymphs) and 0.71 (male adults). The group of medium nymphs was the only one whose behavior was not significantly altered by exposure to DEET. The results show the importance of assessing insect repellents at different stages of the insect's life cycle in order to obtain a complete panorama of its effect.

Volatile Composition and Biological Activities of the Leaf Essential Oil from Zanthoxylum limoncello Grown in Oaxaca, México.

Zanthoxylum limoncello is a native plant from southern Mexico which is used as a timber source, condiment and as a traditional medicine. Herein, we report on the volatile content of the leaf essential oil and its biological activities. The annual essential oils (2015-2018) contained volatile organic compounds which exhibited a moderate growth inhibitory activity against H. pylori ATCC 53504 (MIC 121.4-139.7 µg mL-1 ), 26695 (MIC 85.5-94.9 µg mL-1 ) and J99 (MIC 94.7-110.4 µg mL-1 ). These hydrodistillates contained 2-undecanone (31.6-36.8 %; MIC 185.3-199.2 µg mL-1 ) and 2-undecenal (25.1-35.7 %; MIC 144.8-111.3 µg mL-1 ) as the most abundant compounds which were partially involved in the anti-H. pylori activity. The human ornithine decarboxylase enzyme (ODC1), which shows increased activity in several cancer types, was non-competitively inhibited (Vmax 2.7>0.8 Kcat s-1 ) by the essential oil of Z. limoncello as well as by 2-undecanone and 2-undecenal in accordance to in vitro kinetic studies. In silico calculations strongly suggest that the carbonyl group of these oxygenated hydrocarbons interacts with both Asn319 and Ala39 at the subunit A of ODC1. Considering that Ala39 is located close to Asn44, a crucial amino acid of the ODC's allosteric site, the non-competitive inhibition of the enzyme by 2-undecanone and 2-undecenal is endorsed. Finally, the essential oil of Z. limoncello and its main volatiles showed a significant (p<0.01) and prolonged repellent effect against Aedes aegypti.

Pyrethroid Resistance Associated With a Decreased DEET Repellency in the Common Bed Bug (Hemiptera: Cimicidae).

The global resurgence of the bed bug (Cimex lectularius L.) and the widespread resistance of this insect to pyrethroid insecticides have created the need to find alternatives to chemical control. Thus, synthetic or natural repellents have been considered as a suitable choice to control bed bug infestations. Repellents not only keep insects away from their hosts, but also allow a decrease in insecticide selection pressure. The aim of this study was to evaluate the repellence effectivity of DEET against two bed bug colonies from Argentina (a susceptible one and a field-collected pyrethroid-resistant one), under two starving periods. We found different repellent effects of DEET on the two C. lectularius colonies and no differences between the two starving periods. In fact, DEET had a lower effect on the insecticide-resistant colony. The methodology used in this study proved to be useful to test the variation of the effect of DEET between pyrethroid-susceptible and -resistant bed bugs.

Pyrethroid Resistance Associated With a Decreased DEET Repellency in the Common Bed Bug (Hemiptera: Cimicidae)

The global resurgence of the bed bug (Cimex lectularius L.) and the widespread resistance of this insect to pyrethroid insecticides have created the need to find alternatives to chemical control. Thus, synthetic or natural repellents have been considered as a suitable choice to control bed bug infestations. Repellents not only keep insects away from their hosts, but also allow a decrease in insecticide selection pressure. The aim of this study was to evaluate the repellence effectivity of DEET against two bed bug colonies from Argentina (a susceptible one and a fieldcollected pyrethroid-resistant one), under two starving periods. We found different repellent effects of DEET on the two C. lectularius colonies and no differences between the two starving periods. In fact, DEET had a lower effect on the insecticide-resistant colony. The methodology used in this study proved to be useful to test the variation of the effect of DEET between pyrethroid-susceptible and -resistant bed bugs.

Spraying pyrethroid and neonicotinoid insecticides can induce outbreaks of Panonychus citri (Trombidiformes: Tetranychidae) in citrus groves.

Panonychus citri (McGregor) (Trombidiformes: Tetranychidae) is one of the main defoliator mites in citrus groves. In Brazil, P. citri was formerly considered a secondary pest, but in recent years, the population levels of this mite have increased in many groves, requiring additional acaricide applications for its control. The population growth of P. citri is associated with the increase in the number of applications of pyrethroid and neonicotinoid insecticides to control insect citrus pests. This study assessed the effects of pyrethroid (deltamethrin, esfenvalerate, λ-cyhalothrin) and neonicotinoid (imidacloprid and thiamethoxam) insecticides on biological, behavioral and demographic parameters of P. citri. None of the insecticides tested affected larval hatching, but deltamethrin, esfenvalerate, and λ-cyhalothrin reduced the survival of larvae and protonymphs. Deltamethrin, esfenvalerate, and λ-cyhalothrin induced a significant increase in the fecundity of surviving females. Pyrethroids also caused repellency and changed feeding and oviposition preferences. In contrast, imidacloprid and thiamethoxam did not affect the survival of immature stages, but imidacloprid significantly increased fecundity. Imidacloprid and thiamethoxam did not cause any repellent effect or changes in the feeding and oviposition preferences. Based on the demographic parameters, deltamethrin, λ-cyhalothrin, and imidacloprid increased Ro, r, and λ, whereas esfenvalerate and thiamethoxam were similar to the control. Therefore, the use of these insecticides (especially deltamethrin, λ-cyhalothrin, and imidacloprid) requires caution, such as avoiding repeated use of these compounds during the periods of P. citri incidence in citrus groves.

Chemical profile and pharmacological effects of the resin and essential oil from Bursera slechtendalii: A medicinal "copal tree" of southern Mexico.

This study reports on the volatile profile and pharmacological activities of the essential oil and resin from Bursera slechtendalii, an aromatic medicinal tree commercialized in southern Mexico. The essential oil contained 25 volatiles including p-cymen-8-ol (25.4-35.7%), n-hexyl hexanoate (6.8-17.6%) and n-octyl hexanoate (7.6-14.8%), whereas the crystallized resin contained 14 volatiles, including n-octyl acetate (29.6-34.2%), limonene (15.8-18.7%) and n-octyl butyrate (12.6-17-6%). The inhalation of vapors from the resin and essential oil caused a significant anxiolytic-like effect (p < .01) in ICR mice after 20 min of exposure at a dose of 50-150 mg L-1. The prolonged inhalation of the essential oil (for 40 days, for 15 min, twice a day) produced a significant decrease (p < .01) in total cholesterol and LDL-c content as well as an increase of HDL-c levels in the same murine model. Interestingly, levels of hepatic lipid hydroperoxide decreased, whereas the hepatic activity of superoxide dismutase and glutathione peroxidase was significantly enhanced (P < .05). The detection of p-cymen-8-ol and n-octyl acetate in the plasma of mice strongly suggests their bioavailability and possible role in the biological activities described herein. Also, both the resin and essential oil from B. slechtendalii, as well as their main volatiles, showed a potent repellence activity against Aedes aegypti (p < .01).

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.

Chemical Composition of Alphitobius diaperinus (Coleoptera: Tenebrionidae) Abdominal Glands and the Influence of 1,4-benzoquinones on its Behavior.

This study aimed to identify and quantify the compounds present in the abdominal glands of Alphitobius diaperinus Panzer, 1797 (Coleoptera: Tenebrionidae) and to evaluate the influence of these compounds on its behavior. The extraction of volatiles present in the abdominal glands was made by dissection (10 individuals per sex) and by air entrainment (200 insects per sex), and they were analyzed by gas chromatography-flame ionization detector, gas chromatograph-mass spectrometer, and gas chromatograph-electroantennography detector (GC-EAD). The influence of these volatiles on the behavior of conspecifics was evaluated in a four-arm olfactometer. Twenty-three compounds were identified from male and female abdominal gland extracts, of which six were quinones: the 2-methyl-1,4-benzoquinone and the 2-ethyl-1,4-benzoquinone were the major components, and 1,4 benzoquinone and three hydroquinones were registered for the first time for this species. The GC-EAD analysis using the crude extracts from abdominal glands showed that male and female antennae responded to the three major benzoquinones. For the olfactometer bioassays, both genders were repelled either by the abdominal gland extracts or by synthetic solutions containing the three benzoquinones. The results suggest that the 1,4-benzoquinones play a role as a repellent to A. diaperinus.

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.