RESUMEN

Insecticide plants are an important tool among the new alternatives for pest control in IPM systems because they reduce the use of synthetic insecticides, preserving human health and the environment. We investigated the effects of aqueous extracts of Melia azedarach leaves and Azadirachta indica seeds and three tomato genotypes, 'Santa Clara', 'IPA-5'--Solanum lycopersicum (=Lycopersicon esculentum Mill), and LA444-1--S. peruvianum (=L. peruvianum), on the development, reproduction and longevity of the tomato pinworm Tuta absoluta (Meyrick), under laboratory conditions. The trials were set up in a completely randomized design, with nine treatments [three genotypes x two extracts (M. azedarach and A. indica) and control]. The replication consisted on five tubes, each with three newly hatched larvae, totalizing 90 individuals per treatment. The larvae were fed with tomato leaves treated with aqueous extracts at 0.1% concentration or distilled water (control) and daily observed until adults' emergence. Larval and pupal development and mortality, pupal weight, longevity and fecundity were evaluated. The accession LA444-1 negatively affected the development and reproduction of T. absoluta; the tomato pinworm had similar development and reproduction on 'IPA-5' and 'Santa Clara' (the susceptible control). The association of resistant tomato genotypes and extracts of M. azedarach leaves and neem seeds did not result in synergistic or antagonistic effects on T. absoluta.

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Brazil is one of the world's largest tomato producer, but considerable part of the production is lost due to the attack of Bemisia tabaci (Genn.) B biotype. Resistant germoplasm plants can be an important method for B. tabaci control in integrated pest management approaches. The attractiveness and ovipositional preference of B. tabaci for 17 tomato genotypes were evaluated in a free-choice test. Trials were set up in a randomized block design with ten replicates. Each replicate (one tomato plant per pot) was placed in a cage (80 x 50 x 50 cm) and infested with 1,000 adults during four days. Linear correlation tests were applied between the number of insects and eggs and number of trichomes in each tomato genotype. LA716, LA444-1 and PI134418 genotypes were the least attractive, while the 'Santa Clara' was the most attractive; PI134417 trapped the largest number of adults. LA716 genotype (4.1 eggs/leaflet and 2.1 cm²/eggs per leaflet) was the least preferred for whitefly oviposition; NAV1062, 'Fanny', LA1335, 'Santa Clara' and IAC294 were the most preferred genotypes. The glandular trichomes density was negatively correlated with whitefly's attractiveness and oviposition per leaflet and per leaf, and positively with the number of trapped insects. The non-glandular trichomes density was negatively correlated with the number of trapped insects and positively with whitefly's oviposition per cm²/leaflet andper cm²/leaf. LA716 had high antixenosis level (ovipositional nonpreference) toward B. tabaci B biotype related with type IV glandular trichome.

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Insecticide plants are an important tool among the new alternatives for pest control in IPM systems because they reduce the use of synthetic insecticides, preserving human health and the environment. We investigated the effects of aqueous extracts of Melia azedarach leaves and Azadirachta indica seeds and three tomato genotypes, 'Santa Clara', 'IPA-5' - Solanum lycopersicum (= Lycopersicon esculentum Mill), and LA444-1 - S. peruvianum (= L. peruvianum), on the development, reproduction and longevity of the tomato pinworm Tuta absoluta (Meyrick), under laboratory conditions. The trials were set up in a completely randomized design, with nine treatments [three genotypes x two extracts (M. azedarach and A. indica) and control]. The replication consisted on five tubes, each with three newly hatched larvae, totalizing 90 individuals per treatment. The larvae were fed with tomato leaves treated with aqueous extracts at 0.1 percent concentration or distilled water (control) and daily observed until adults' emergence. Larval and pupal development and mortality, pupal weight, longevity and fecundity were evaluated. The accession LA444-1 negatively affected the development and reproduction of T. absoluta; the tomato pinworm had similar development and reproduction on 'IPA-5' and 'Santa Clara' (the susceptible control). The association of resistant tomato genotypes and extracts of M. azedarach leaves and neem seeds did not result in synergistic or antagonistic effects on T. absoluta.

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The colonization of Spodoptera frugiperda J.E. Smith larvae and rice seedlings by genetically modified endophytic bacterium Methylobacterium mesophilicum, and also the possible transfer of this bacterium to inside the larva's body during seedlings consumption were studied. The data obtained by bacterial reisolation and fluorescence microscopy showed that the bacterium colonized the rice seedlings, the larva's body and that the endophytic bacteria present in seedlings could be acquired by the larvae. In that way, the transference of endophytic bacterium from plants to insect can be a new and important strategy to insect control using engineered microorganisms.

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The colonization of Spodoptera frugiperda J.E. Smith larvae and rice seedlings by genetically modified endophytic bacterium Methylobacterium mesophilicum, and also the possible transfer of this bacterium to inside the larva's body during seedlings consumption were studied. The data obtained by bacterial reisolation and fluorescence microscopy showed that the bacterium colonized the rice seedlings, the larva's body and that the endophytic bacteria present in seedlings could be acquired by the larvae. In that way, the transference of endophytic bacterium from plants to insect can be a new and important strategy to insect control using engineered microorganisms.

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Brazil is one of the world's largest tomato producer, but considerable part of the production is lost due to the attack of Bemisia tabaci (Genn.) B biotype. Resistant germoplasm plants can be an important method for B. tabaci control in integrated pest management approaches. The attractiveness and ovipositional preference of B. tabaci for 17 tomato genotypes were evaluated in a free-choice test. Trials were set up in a randomized block design with ten replicates. Each replicate (one tomato plant per pot) was placed in a cage (80 x 50 x 50 cm) and infested with 1,000 adults during four days. Linear correlation tests were applied between the number of insects and eggs and number of trichomes in each tomato genotype. LA716, LA444-1 and PI134418 genotypes were the least attractive, while the 'Santa Clara' was the most attractive; PI134417 trapped the largest number of adults. LA716 genotype (4.1 eggs/leaflet and 2.1 cm²/eggs per leaflet) was the least preferred for whitefly oviposition; NAV1062, 'Fanny', LA1335, 'Santa Clara' and IAC294 were the most preferred genotypes. The glandular trichomes density was negatively correlated with whitefly's attractiveness and oviposition per leaflet and per leaf, and positively with the number of trapped insects. The non-glandular trichomes density was negatively correlated with the number of trapped insects and positively with whitefly's oviposition per cm²/leaflet andper cm²/leaf. LA716 had high antixenosis level (ovipositional nonpreference) toward B. tabaci B biotype related with type IV glandular trichome.

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The objective of this work was to evaluate the influence of the leaf surface, the insect geotropic behavior and the type of foliar trichome on Bemisia tabaci (Genn.) biotype B oviposition on tomato leaves. Bemisia tabaci females were confined in acrylic boxes in which tomato leaflets were fixed at the bottom and top part of the boxes to allow insects to access the leaf surface to be tested (adaxial and/or abaxial) in both no-choice and free choice tests. Oviposition was always higher when the leaf was offered at the top of the box and preferably at the abaxial leaf surface. The effects of leaf trichomes (glandular and non glandular) on B. tabaci oviposition was evaluated by offering the abaxial surface of tomato leaflets to females after a 70% ethanol wash to remove glandular exsudates against a control treatment (without a ethanol wash). Oviposition was concentrated mostly near to non glandular trichomes, showing whitefly females can discriminate among the trichomes.

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Avaliou-se a influência da face foliar, do comportamento geotrópico do inseto e do tipo de tricoma foliar sobre a oviposição de Bemisia tabaci (Genn.) biótipo B em folhas de tomateiro. Para avaliação desses efeitos foram realizados vários ensaios nos quais as fêmeas foram confinadas em caixas de acrílico. Folíolos de tomateiro foram fixados no topo e na base das caixas, de tal forma a permitir o acesso dos insetos às faces adaxial e abaxial de maneira isolada e concomitante (com e sem chance de escolha). Os insetos sempre depositaram maior número de ovos quando a superfície foliar se encontrava no topo da caixa e, de maneira geral, preferiram depositar seus ovos na face abaxial dos folíolos. Para avaliar o efeito do tipo de tricoma (glandular e não-glandular) sobre a oviposição de B. tabaci, a face abaxial dos folíolos de tomateiro foi oferecida a cerca de 30 fêmeas para oviposição em cada caixa de acrílico. Foram oferecidos folíolos previamente lavados com etanol a 70 por cento (de forma a eliminar os exsudatos glandulares) e sem lavagem prévia. A maior parte da oviposição ocorreu ao lado dos tricomas não-glandulares, demonstrando que o inseto discrimina o tipo de tricoma.

The objective of this work was to evaluate the influence of the leaf surface, the insect geotropic behavior and the type of foliar trichome on Bemisia tabaci (Genn.) biotype B oviposition on tomato leaves. Bemisia tabaci females were confined in acrylic boxes in which tomato leaflets were fixed at the bottom and top part of the boxes to allow insects to access the leaf surface to be tested (adaxial and/or abaxial) in both no-choice and free choice tests. Oviposition was always higher when the leaf was offered at the top of the box and preferably at the abaxial leaf surface. The effects of leaf trichomes (glandular and non glandular) on B. tabaci oviposition was evaluated by offering the abaxial surface of tomato leaflets to females after a 70 percent ethanol wash to remove glandular exsudates against a control treatment (without a ethanol wash). Oviposition was concentrated mostly near to non glandular trichomes, showing whitefly females can discriminate among the trichomes.

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A partir do extrato em diclorometano (DIC) de folhas e frutos de Trichilia pallida Swartz, objetivou-se fazer o isolamento e identificação de substâncias com atividade inseticida sobre a traça-do-tomateiro, Tuta absoluta (Meyrick). Do extrato em DIC de folhas de T. pallida foram isolados os triterpenos 24-metilenocicloarta-3β-ol (TRIT-1), 24-metilenocicloarta-3β-26-diol (TRIT-2) e cicloarta-23-eno-3β,25-diol (TRIT-3), os esteróides 24-metileno-3,22-diidroxicolesterol (EST-1), 24-metilenocolesterol (EST-2) e 24-metileno-3β,4β,22-triidroxicolesterol (EST-3), além do limonóide gedunina (LIM) obtido de frutos da planta. As substâncias foram dissolvidas em acetona e pulverizadas a 0,1% em folíolos de tomateiro infestados com lagartas recém-eclodidas. Foram avaliadas a mortalidade de lagartas aos quinto e nono dias após a infestação, duração e sobrevivência das fases de larva e pupa, peso de pupas e porcentagem de adultos deformados. TRIT-1, EST-1 e LIM foram as moléculas que apresentaram maior atividade sobre T. absoluta, alongando o desenvolvimento larval e reduzindo a sobrevivência dessa fase.

Dichloromethane (DIC) leaf and fruit extracts of Trichiliapallida Swartz were obtained for the isolation and identification of molecules with insecticidal activity against the tomato leafminer, Tuta absoluta (Meyrick). DIC leaf extracts of T. pallida yielded six compounds, the triterpenes 24-methylenecycloarta-3β-ol (TRIT-1), 24-methylenecycloarta-3β-26-diol (TRIT-2) and cycloarta-23-eno-3β,25-diol (TRIT-3), the sterols 24-methylene-3,22-dihydroxycholesterol (EST-1), 24-methylenecholesterol (EST-2) and 24-methylene-3β,4β,22-trihydroxycholesterol (EST-3), while the fruit extract yielded the limonoid gedunine (LIM). These molecules were dissolved in acetone and sprayed at 0.1% on tomato leaflets infested with newly-hatched larvae. Larval mortality at day 5 and 9 after infestation, larval and pupal developmental time and survival, pupal weight and adult malformation were evaluated. TRIT-1, EST-1 and LIM were the most effective against T. absoluta due to larval development arrestment and reduced larval survivorship.

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The silverleaf whitefly is one of the most harmful pests that attack bean crops, mainly for extracting large quantities of phloem sap and transmitting the bean golden mosaic virus. Resistant germoplasm plants can be an important method for controlling this pest. The biological aspects of Bemisia tabaci B biotype on bean (Phaseolus vulgaris) genotypes were evaluated. The tests were conducted under laboratory conditions, with the following genotypes: Arc 1, Arc 3s, Arc 5s, G13028, G11056 and Porrillo 70. The bean plants in a stage IV-1 were infested during one day with silverleaf whiteflies. Afterwards the eggs and nymphs were observed until adult emergence. Longevity and fecundity of emerged insects were also evaluated. The longest development time occurred for nymphs fed on Arc 3s genotype (26.5 days), following by G11056 (25.9 days) and G13028 (25.3 days). The development period was 5.5 days longer in Arc 3s when compared with Porrillo 70. Also, the wild genotypes Arc 3s and G11056 showed higher mortality rates (94.7% and 83.1%, respectively), which may suggest antibiosis and/or feeding nonpreference resistance type. For this reason, although longevity and fecundity were not influenced when the whitefly fed on resistant genotypes (Arc 3s, G11056, G13028 and Arc 5s), those genotypes can be used for bean breeding program towards B. tabaci B biotype.

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A mosca-branca é um dos insetos mais prejudiciais à cultura do feijoeiro, devido principalmente à intensa sucção de seiva e à transmissão do vírus do mosaico dourado. O uso de cultivares resistentes ao inseto é uma ferramenta importante no seu controle. Ensaios foram conduzidos em laboratório, avaliando-se aspectos biológicos de Bemisia tabaci biótipo B para os seguintes genótipos de feijoeiro: Arc 3s, Arc 5s, G13028, G11056, Arc 1 e Porrillo 70. As plantas (estágio IV-1) foram infestadas por moscas-brancas durante um dia e os ovos e ninfas foram observados até a emergência dos adultos. A longevidade e a fecundidade dos insetos emergidos também foram avaliadas. Ninfas alimentadas no genótipo Arc 3s (26,5 dias) tiveram o período de desenvolvimento mais longo, seguidas de G11056 (25,9 dias) e G13028 (25,3 dias). Houve um alongamento de 5,5 dias no período de desenvolvimento dos insetos em Arc 3s quando comparado com Porrillo 70. Altas taxas de mortalidade das ninfas nos genótipos Arc 3s e G11056 (94,7 e 83,1 por cento, respectivamente) indicam que tais materiais podem apresentar resistência do tipo não-preferência para alimentação e/ou antibiose. Assim, embora a longevidade e a fecundidade do inseto não tenham sido afetadas quando criado nos genótipos resistentes (Arc 3s, G11056, G13028 e Arc 5s), sugere-se que tais materiais sejam utilizados em programas de melhoramento de feijoeiro visando à resistência a B. tabaci biótipo B.

The silverleaf whitefly is one of the most harmful pests that attack bean crops, mainly for extracting large quantities of phloem sap and transmitting the bean golden mosaic virus. Resistant germoplasm plants can be an important method for controlling this pest. The biological aspects of Bemisia tabaci B biotype on bean (Phaseolus vulgaris) genotypes were evaluated. The tests were conducted under laboratory conditions, with the following genotypes: Arc 1, Arc 3s, Arc 5s, G13028, G11056 and Porrillo 70. The bean plants in a stage IV-1 were infested during one day with silverleaf whiteflies. Afterwards the eggs and nymphs were observed until adult emergence. Longevity and fecundity of emerged insects were also evaluated. The longest development time occurred for nymphs fed on Arc 3s genotype (26.5 days), following by G11056 (25.9 days) and G13028 (25.3 days). The development period was 5.5 days longer in Arc 3s when compared with Porrillo 70. Also, the wild genotypes Arc 3s and G11056 showed higher mortality rates (94.7 percent and 83.1 percent, respectively), which may suggest antibiosis and/or feeding nonpreference resistance type. For this reason, although longevity and fecundity were not influenced when the whitefly fed on resistant genotypes (Arc 3s, G11056, G13028 and Arc 5s), those genotypes can be used for bean breeding program towards B. tabaci B biotype.

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Dichloromethane (DIC) leaf and fruit extracts of Trichiliapallida Swartz were obtained for the isolation and identification of molecules with insecticidal activity against the tomato leafminer, Tuta absoluta (Meyrick). DIC leaf extracts of T. pallida yielded six compounds, the triterpenes 24-methylenecycloarta-3beta-ol (TRIT-1), 24-methylenecycloarta-3beta-26-diol (TRIT-2) and cycloarta-23-eno-3beta,25-diol (TRIT-3), the sterols 24-methylene-3,22-dihydroxycholesterol (EST-1), 24-methylenecholesterol (EST-2) and 24-methylene-3beta,4beta,22-trihydroxycholesterol (EST-3), while the fruit extract yielded the limonoid gedunine (LIM). These molecules were dissolved in acetone and sprayed at 0.1% on tomato leaflets infested with newly-hatched larvae. Larval mortality at day 5 and 9 after infestation, larval and pupal developmental time and survival, pupal weight and adult malformation were evaluated. TRIT-1, EST-1 and LIM were the most effective against T. absoluta due to larval development arrestment and reduced larval survivorship.

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Pyemotidae mites have been reported as ectoparasites of a large number of arthropods, especially of insects. These mites are frequently found attacking insects in different habitats, including insect rearing. This paper reports the occurrence of Pyemotes sp., ventricosus group, in colonies of Tuta absoluta (Meyerick) (Lepidoptera: Gelechiidae), Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae) and Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), in the insect rearing laboratory of ESALQ-USP, in Piracicaba, State of São Paulo, provoking dematitis in those involved with the rearing. This is the first report of a Pyemotes species parasitizing T. absoluta and S. zeamais. Considering the capacity of Pyemotes to cause dermatitis in human beings, demonstrated by other authors, the direct use of the Pyemotes species found in this work for the control of the reported insect species may not be promising.

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The effects of crude extracts, fractions and isolated compounds from Vitex polygama Cham. and Siphoneugena densiflora Berg were evaluated on the development of Spodoptera frugiperda JE Smith, a destructive insect pest of corn and several other crops. The extracts and fractions were incorporated into an artificial diet at 1 mg g(-1) and offered to the insect during its larval stage. Length and viability of larval and pupal stages as well as pupal weight were assessed. Isolated compounds were tested through superficial contamination of the diet at 0.1 mg g(-1). Weight and viability of ten-day-old larvae were determined. Methanolic and hydroalcoholic S. densiflora extracts caused 100% larval mortality, while leaf and fruit hydroalcoholic extracts from V. polygama were the most active. Among the isolated compounds, flavonoids presented the best insecticidal results, and tannins the best larval growth inhibition.

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Acaros Pyemotidae são relatados como ectoparasitos de grande número de artrópodes, principalmente de insetos. Estes ácaros são freqüentemente encontrados atacando insetos em diferentes habitats, inclusive em criações de laboratório. Relata-se neste trabalho a ocorrência de Pyemotes sp., grupo ventricosus, em criações da traça-do-tomateiro, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), da traça-das-farinhas, Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae), e do gorgulho-do-milho, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), no laboratório de criação de insetos da ESALQ-USP, em Piracicaba, SP, inclusive causando dermatites nas pessoas envolvidas com as criações. Este é o primeiro registro do parasitismo de Pyemotes sp. em lagartas de T. absoluta e larvas de S. zeamais. Pelo fato de estes ácaros causarem dermatites em seres humanos, demonstrada por outros autores, o uso direto da espécie de Pyemotes encontrada neste trabalho para o controle dos insetos citados possa não ser promissor.

Pyemotidae mites have been reported as ectoparasites of a large number of arthropods, especially of insects. These mites are frequently found attacking insects in different habitats, including insect rearing. This paper reports the occurrence of Pyemotes sp., ventricosus group, in colonies of Tuta absoluta (Meyerick) (Lepidoptera: Gelechiidae), Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae) and Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), in the insect rearing laboratory of ESALQ-USP, in Piracicaba, State of São Paulo, provoking dematitis in those involved with the rearing. This is the first report of a Pyemotes species parasitizing T. absoluta and S. zeamais. Considering the capacity of Pyemotes to cause dermatitis in human beings, demonstrated by other authors, the direct use of the Pyemotes species found in this work for the control of the reported insect species may not be promising.

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Bemisia tabaci (Genn.) é uma das principais pragas do tomateiro no Brasil, provocando severas perdas devido à sucção de seiva, indução do amadurecimento irregular dos frutos e transmissão de viroses. O objetivo deste trabalho foi determinar o efeito de tricomas glandulares no desenvolvimento de B. tabaci biótipo B em oito genótipos de tomateiro, em casa de vegetação. Utilizou-se o delineamento de blocos ao acaso, em arranjo fatorial (genótipo x exsudato), com três repetições, sendo os genótipos avaliados na condição com e sem exsudato. Adultos da mosca-branca foram transferidos para uma gaiola de voil, onde permaneceram durante 24h. As variáveis avaliadas foram número de ovos e viabilidade, período de incubação, número de ninfas, duração e sobrevivência da fase ninfal. Efetuou-se a contagem de tricomas e a determinação do pH e teor de acilglicose para todos os genótipos. Na presença de exsudato, LA716 proporcionou redução na oviposição do inseto, o que sugere efeito antixenótico. Resistência antixenótica em LA1739 e PI134417 não foi associada ao exsudato glandular. O efeito do exsudato na oviposição do inseto foi explicado pelo teor de acilglicose. O pH apresentou papel secundário na oviposição da mosca-branca. A densidade de tricomas favoreceu o desenvolvimento do inseto. LA1584 destacou-se pela redução na sobrevivência do inseto e prolongamento do ciclo, além de propiciar oviposição intermediária, podendo ser adequado para incorporação em programas de melhoramento. Entretanto, há necessidade de estudos adicionais para determinar o potencial de uso desse genótipo ou de seus híbridos no manejo integrado de pragas.

Bemisia tabaci (Genn.) is one of the most important tomato pests in Brazil and causes severe losses due to the sap suction, the induction of the irregular ripening of the fruit and virus transmission. The objective of this study was to determine the effect of exudates released by the glandular trichomes on the development of B. tabaci biotype B on eight tomato genotypes, under greenhouse conditions. The experiment was arranged as a factorial scheme (genotype x exudate) in a randomized block design, with three replications, being the genotypes evaluated in two conditions (with and without exudate). Whitefly adults were transferred to a voile cage for 24h. The variables evaluated were number of eggs and viability, incubation period, number of nymphs, duration and viability of the nymphal stage. Trichome counts and determination of pH and acylglucose content were made for all the genotypes. Intact leaflets of LA716 were less accepted for oviposition than leaflets without exudate, which suggests an antixenotic effect. Antixenotic resistance in LA1739 and PI134417 was not associated to the glandular exudate. The effect of exudates on the insect oviposition was explained by the acylglucose content. The pH showed secondary role on the whitefly oviposition. Trichomes density improved the insect development. LA1584 reduced the insect survival and increased its cycle, besides promoting an intermediate oviposition. For this reason, it can be useful in breeding programs. However, further studies are needed to determine the potential of this genotype and hybrids for future utilization in integrated pest management.

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A partir de extratos aquosos e não aquosos de Trichilia pallida Swartz (Meliaceae), objetivou-se identificar frações com atividade inseticida sobre a traça-do-tomateiro, Tuta absoluta (Meyrick). Para tanto, extratos aquosos liofilizados (EAL) a 3 por cento, de folhas e ramos da planta, foram ressuspendidos em água e aplicados, por meio de mini-atomizador, sobre folíolos de tomateiro infestados com lagartas recém-eclodidas. Com base nos resultados de mortalidades aos 5 e 10 dias após a infestação (DAI), considerou-se o EAL de folhas mais eficiente que o de ramos. Numa segunda etapa, foram obtidos por maceração, extratos de folhas em hexano (HEX), diclorometano (DIC) e metanol (MET), os quais foram avaliados a1 por cento (p/v) como descrito anteriormente, incluindo-se acetona e água como controles. Dentre os referidos extratos, aquele em DIC foi o mais promissor como fonte de substância(s) com atividade inseticida sobre lagartas de T. absoluta. Na seqüência, através de partição líquido-líquido do extrato DIC, obtiveram-se as frações em HEX, MET, acetato de etila (AET), n-butanol (NBU) e aquosa (AQ). Destas frações, a AET e MET a 0,15 por cento foram consideradas as mais promissoras como fontes de substâncias com atividade inseticida sobre T. absoluta.

Organic and aqueous extracts of the Trichilia pallida Swartz (Meliaceae) were obtained for identification of fractions with insecticidal activity against the tomato leafminer Tuta absoluta (Meyrick). Leaf and twig freeze-dried aqueous extracts (FDA) were resuspended in water at 3 percent and sprayed, with the aid of a mini-atomizer, over tomato leaflets infested with newly-hatched larvae. Larval mortality at 5 and 10 days after infestation (DAI) were higher for leaf extracts. In a second set of experiments, leaf extracts at 1 percent (w/v) were obtained by maceration in hexane (HEX), dichloromethane (DIC) and methanol (MET), and tested as described above using acetone and water as control. DIC extracts were the most promising as a source of substances with insecticidal activity against larvae of T. absoluta. DIC leaf extracts were further processed and subjected to partition assays, producing fractions in HEX, MET, ethyl acetate (ETA), n-butanol (NBU) and water (WA). The 0.15 percent ETA and MET fractions obtained from the partition assay of DIC extracts showed the highest insecticidal activity against T. absoluta.

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Visando avaliar os possíveis mecanismos de resistência de diferentes genótipos de tomateiro (Lycopersicon spp.) em relação à mosca-branca Bemisia tabaci (Gennadius) biótipo B, realizaram-se ensaios em casa-de-vegetação e laboratório. Os genótipos estudados foram 'IAC-Santa Clara' (L. esculentum), PI-127826 (L. hirsutum), PI-134417 e PI-134418 (L. hirsutum f. glabratum), LA-716 (L. pennellii), LA-371 e LA-444-1 (L. peruvianum), LA-1584 e PI-126931 (L. pimpinellifolium). Em casa-de-vegetação, LA-716, PI-134417 e PI-134418 foram os menos atrativos à mosca-branca; o genótipo LA-716 expressou elevado nível de não-preferência; PI-134417, PI-134418, PI-127826 e PI-126931 também foram considerados resistentes, porém em níveis mais baixos. Tomando-se o período total de desenvolvimento (ovo-adulto), os genótipos PI-127826, PI-134417, PI-134418 e LA-444-1 prolongaram o ciclo do inseto, indicando a ocorrência de não-preferência para alimentação e/ou antibiose.

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Na busca de alternativas para o manejo de pragas, as plantas inseticidas apresentam-se como ferramenta promissora, pois podem reduzir o uso de inseticidas sintéticos, amenizando os impactos prejudiciais ao homem e ao ambiente. Neste trabalho, foi avaliado o efeito de extratos aquosos de ramos e folhas de seis espécies de Trichilia (T. casaretti, T. catigua, T. clausseni, T. elegans, T. pallens e T. pallida), sobre o desenvolvimento de Spodoptera frugiperda (J.E. Smith) em condições de laboratório. Folhas de milho foram imersas nos extratos a 1 por cento (peso/volume) e, depois de evaporado o excesso de água, fornecidas a lagartas de primeiro ínstar. Avaliou-se o efeito na sobrevivência, duração e peso de lagartas e pupas. Os extratos de ramos de T. pallida e de folhas de T. pallens foram os mais eficientes, dentre as seis espécies de Trichilia testadas, embora os extratos de folhas de T. pallida, T. catigua, T. casaretti e T. elegans e os extratos de ramos de T. clausseni e T. pallens também tenham afetado o desenvolvimento do inseto.

Among the new alternatives to pest control according to IPM systems, insecticide plants are an important tool because they reduce the use of synthetic insecticides, so preserving human health and the environment. The activity of aqueous extracts of leaves and twigs from six Trichilia species (T. casaretti, T. catigua, T. clausseni, T. elegans, T. pallens and T. pallida) was evaluated on Spodoptera frugiperda (J.E. Smith) development in laboratory conditions. Maize leaves immerged in each extract 1 percent (weight/volume) were dried and then provided to the first instar larvae. The effect of the extracts on survival, duration and weight of larval and pupal period was evaluated. The extracts from twigs of T. pallida and leaves of T. pallens were more efficient although the extracts from leaves of T. pallida, T. catigua, T. casaretti and T. elegans and twigs of T. clausseni and T. pallens also have affected the insect development.

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RESUMEN

Este trabalho teve como objetivo avaliar a influência do pó e do extrato aquoso de Chenopodium ambrosioides L. sobre o comportamento e a sobrevivência do gorgulho-do-milho, Sitophilus zeamais Mots. As plantas de C. ambrosioides foram cultivadas na área experimental do Departamento de Entomologia, Fitopatologia e Zoologia Agrícola da ESALQ/USP. Foram obtidos pós de folhas, ramos, frutos e da planta inteira (com frutos), quando a planta estava no estágio de frutificação. Os insetos utilizados nos ensaios foram obtidos de criação mantida em grãos de trigo. Foi avaliado o efeito do pó das diferentes estruturas vegetais e da planta inteira (com frutos) sobre o comportamento (atratividade e/ou repelência) e atividade inseticida nos adultos. Foi avaliado também o potencial inseticida do extrato aquoso das diferentes estruturas e da planta inteira (com frutos) sobre as fases imatura e adulta de S. zeamais. Os resultados obtidos foram: a) pós de frutos, ramos e folhas de C. ambrosioides não apresentaram repelência para adultos de S. zeamais; b) os pós de frutos e da planta inteira (com frutos) apresentaram atividade inseticida sobre adultos de S. zeamais; c) os extratos aquosos dessas estruturas vegetais não afetaram a sobrevivência e a emergência de adultos de S. zeamais.

This work deals with the influence of the powder and aqueous extracts of Chenopodium ambrosioides L. on behaviour and survival of the maize weevil, Sitophilus zeamais Mots. The powders tested were obtained from leaves, branches, fruits and the whole plant (with fruits), when the plant was in the fructification period. The insects were obtained from a population reared on wheat grains. The effect of the powders from the different vegetal structures and from the whole plant (with fruits) was evaluated concerning the insect behavior (attractiveness and/or repellence) and insecticide activity on the adult phase. The insecticide activity of the aqueous extract from the different structures and from the whole plant (with fruits) was evaluated on immature and adult S. zeamais. The results were as follows: a) powders from fruits, branches and leaves of C. ambrosioides were not repellent to S. zeamais adults; b) powders from fruits and whole plant (with fruits) presented insecticide activity against S. zeamais adults; c) the aqueous extracts from these structures did not affect survival and adult emergence in S. zeamais.

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