El análisis de la composición química de los artrópodos es importante en la taxonomía, en el reconocimiento de especies de difícil diferenciación, en la ecología, en el comportamiento, en el estudio de la selectividad de compuestos naturales y artificiales y, por consiguiente, importante en el control de plagas. El objetivo de este trabajo fue estudiar la composición química de la cutícula de los ácaros T. urticae y T. evansi. Se realizaron análisis cromatográficos de los extractos por Cromatografía Gaseosa acoplada a Espectrometría de Gases (CGMS). La identificación de los compuestos fue realizada por comparación de los tiempos de retención con patrones, en el cálculo del índice de Kovats y análisis de los espectros de masa obtenidos para cada pico registrado en el cromatograma. Se evaluó la concentración relativa de los compuestos presentes en la cutícula, la polaridad de esos compuestos y su concentración total relativa, y la presencia diferencial de compuestos en la cutícula de las dos especies de ácaros. Los compuestos más abundantes en la cutícula de las dos especies de ácaros fueron el ácido hexadecanoico (ácido palmítico), ácido 9,12-octadecadienoico (ácido linoleico), ácido 9,12,15-octadecatrienoico-metil ester (metil linoleato) y ácido octadecanoico (ácido oleico o esteárico). La cutícula de T. urticae tiene de 2,07 a 3,67 veces más compuestos extraíbles por hexano que la cutícula de T. evansi. El total de compuestos polares fue 2,15 a 3,71 veces mayor en T. urticae y la cantidad de los compuestos más abundantes, presentes en las dos especies, fueron 2,34 a 5,66 veces mayor en T. urticae.

The analysis of arthropods chemical composition is important in taxonomy for recognition of species difficult to differentiate, in ecology, for behavioral analyses, and in selectivity studies of artificial and natural compounds, and, therefore, it is important for pest control. The objective of this study was to evaluate the chemical composition of the T. urticae and T. evansi mites cuticle. Chromatographic analyses of extracts were performed by gas chromatography coupled to mass spectrometry (CGMS). Identification of compounds was based on the comparison of retention times with standards, on the Kovats' index calculation and the analysis of mass spectra obtained for each registered peak on the chromatogram. Relative concentration of compounds present in the cuticle, the polarity of these compounds and their total relative concentration, and the differential presence of compounds in the cuticle of the two mite species were evaluated. The most abundant compounds in the cuticle of both mite species were hexadecanoic acid (palmitic acid), 9,12-octadecadienoico acid (linoleic acid), 9,12,15-octadecatrienoic acid-methyl ester (methyl linoleate) and octadecanoic acid (oleic acid or stearic). T. urticae cuticle has from 2.07 to 3.67 times more hexane extractable compounds than T. evansi cuticle . The total polar compound concentration was 2.15 to 3.71 times higher in T. urticae and the quantity of the most abundant compounds present in both species was 2.34 to 5.66 times higher in T. urticae.

O objetivo deste trabalho foi selecionar plantas com atividade inseticida, para isolar, identificar e avaliar a bioatividade de compostos inseticidas presentes nessas plantas, contra as seguintes pragas de produtos armazenados da ordem Coleoptera: Sitophilus zeamais Mots. (Curculionidae), Rhyzopertha dominica F. (Bostrichidae) e Oryzaephilus surinamensis L. (Silvanidae). As espécies de plantas usadas foram: anis (Ocimum selloi Benth), arruda (Ruta graveolens L.), cordão-de-frade (Leonotis nepetifolia L.), datura (Datura stramonium L.), erva baleeira (Cordia verbenacea L.), hortelã (Mentha piperita L.), melão-de-são-caetano (Mormodica charantia L.) e mentrasto (Ageratum conyzoides L.). Avaliou-se a toxicidade dos extratos hexânico e etanólico dessas plantas sobre R. dominica. Somente o extrato hexânico de A. conyzoides apresentou atividade inseticida. O extrato hexânico desta planta foi fracionado, sucessivamente, por cromatografia de coluna de sílica gel, para isolamento e purificação dos compostos ativos. Os compostos 5,6,7,8,3',4',5'-heptametoxiflavona; 5,6,7,8,3'-pentametoxi-4',5'-metilenodioxiflavona e cumarina foram identificados. Entretanto, somente a cumarina apresentou atividade inseticida às três espécies de insetos (DL50 de 2,72 a 39,71 mg g-1 de i.a.). A ordem crescente de suscetibilidade à cumarina foi R. dominica, S. zeamais e O. surinamensis.

The objective of this work was to screen plants with insecticide activity, in order to isolate, identify and assess the bioactivity of insecticide compounds present in these plants, against Coleoptera pests of stored products: Oryzaephilus surinamensis L. (Silvanidae), Rhyzopertha dominica F. (Bostrichidae) and Sitophilus zeamais Mots. (Curculionidae). The plant species used were: basil (Ocimum selloi Benth.), rue (Ruta graveolens L.), lion's ear (Leonotis nepetifolia (L.) R.Br.), jimson weed (Datura stramonium L.), baleeira herb (Cordia verbenacea L.), mint (Mentha piperita L.), wild balsam apple (Mormodica charantia L.), and billy goat weed or mentrasto (Ageratum conyzoides L.). The insecticide activity of hexane and ethanol extracts from those plants on R. dominica was evaluated. Among them, only hexane extract of A. conyzoides showed insecticide activity; the hexane extract of this species was successively fractionated by silica gel column chromatography, for isolation and purification of the active compounds. Compounds 5,6,7,8,3',4',5'-heptamethoxyflavone; 5,6,7,8,3'-pentamethoxy-4',5'-methilenedioxyflavone and coumarin were identified. However, only coumarin showed insecticide activity against three insect pests (LD50 from 2.72 to 39.71 mg g-1 a.i.). The increasing order of insects susceptibility to coumarin was R. dominica, S. zeamais and O. surinamensis.

O objetivo deste estudo foi determinar os efeitos de clima, predadores e parasitóides, altura de dossel e idade de plantas, composição química foliar, níveis foliares de N e de K e tricomas foliares na intensidade de ataque de Bemisia tabaci em Solanum melongena. A maior densidade de ninfas e de adultos de mosca-branca foi observada nos terços basal e mediano, comparada ao ápice da planta. O maior número de ovos foi observado no terço mediano comparado aos terços apical e basal do dossel das plantas. Um aumento na densidade de mosca-branca está associado com um aumento na temperatura.

The objective of this study was to determine the effects of weather, predators and parasitoids, canopy height and plant age, leaf chemical composition, levels of leaf N and K and leaf trichomes on the intensity of Bemisia tabaci attack on Solanum melongena. A higher density of nymph and whitefly adults was recorded at the base and medium of the plant compared to the apex. A higher number of eggs was observed on the medium part than on the apical and base part of the plants dossel. An increase in the density of whitefly is associated with an increase in temperature.

Este trabalho objetivou determinar os efeitos de pluviosidade e temperatura, predadores e parasitóides, dossel e idade das plantas, tipos e densidades de tricomas foliares, compostos químicos foliares, níveis de N e de K foliares, sobre a intensidade de ataque de mosca-branca Bemisia tabaci (Hemiptera: Aleyrodidae) em jiloeiro Solanum gilo var. 'Gigante Portuguesa'. As densidades de ninfas e de adultos de B. tabaci foram maiores nas folhas baixeiras do que nas apicais das plantas de jiloeiro. Com o aumento da temperatura do ar, observou-se incremento na densidade de adultos de B. tabaci nas folhas de jiloeiro.

The objective of this study was to determine the effect of rainfall and temperature, predators and parasitoids, height within the canopy and plant age, chemical composition of leaves, levels of nitrogen and potassium in leaves and density of trichomes in leaves, on attack intensity of the whitefly Bemisia tabaci (Hemiptera: Aleyrodidae) on Solanum gilo var. 'Portuguese giant'. Densities of nymphs and of adults of B. tabaci were higher on leaves of the lower part than on those of the apical parts of plants of S. gilo. The number of adults of B. tabaci on leaves of S. gilo increased with temperature.