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Resumo -O objetivo deste trabalho foi identificar ácaros na cultura de pinhão-manso e em espécies de plantas espontâneas associadas. Para isso, foram avaliadas a riqueza e a abundância de ácaros em plantas de pinhão-manso e em 14 espécies de plantas espontâneas associadas. As amostragens foram realizadas por meio de coletas mensais de folhas de plantas de pinhão-manso e de plantas espontâneas, nas entrelinhas do cultivo. Foram encontradas quatro espécies de ácaros predadores -Amblyseius tamatavensis, Paraphytoseius multidentatus, Typhlodromalus aripo e Typhlodromalus clavicus -, com potencial para uso no controle biológico de ácaros-praga na cultura do pinhão-manso, e duas importantes espécies de ácaros fitófagos -Brevipalpus phoenicis e Tarsonemus confususdesconhecidas como praga da cultura. Entre as plantas espontâneas avaliadas, quatro espécies -Hyptis suaveolens, Peltaea riedelii, Urochloa mutica e Andropogon gayanus -abrigam grande riqueza e abundância de ácaros predadores, enquanto oito destacaram-se pela diversidade de ácaros fitófagos.Termos para indexação: Jatropha curcas, controle biológico, fitófagos, plantas invasoras. Acarofauna in physic nut culture and associated spontaneous weedsAbstract -The objective of this work was to identify mites in physic nut culture, and in associated spontaneous weed species. For this, mite richness and abundance on physic nut plants and on 14 species of associated spontaneous weeds were evaluated. Samplings were done with monthy collections of leaves from physic nut plants and from weeds, between planting lines. Four species of predatory mites -Amblyseius tamatavensis, Paraphytoseius multidentatus, Typhlodromalus aripo and Typhlodromalus clavicus -, with potential for biological control of pest mites on physic nut culture, and two species of phytophagous mites -Brevipalpus phoenicis and Tarsonemus confusus -, not yet known as pests of the culture were found. Among the evaluated spontaneous weeds, four species -Hyptis suaveolens, Peltaea riedelii, Urochloa mutica and Andropogon gayanus -harbor great richness and abundance of predatory mites, whereas eight harbored a high diversity of phytophagous mites.

Seasonal changes in climate and plant diversity are known to affect the population dynamics of both pests and natural enemies within agroecosystems. In Brazil, spontaneous plants are usually tolerated in small-scale physic nut plantations over the year, which in turn may mediate interactions between pests and natural enemies within this agroecosystem. Here, we aimed to access the influence of seasonal variation of abiotic (temperature, relative humidity and rainfall) and biotic (diversity of spontaneous plants, overall richness and density of mites) factors on the communities of phytophagous and predatory mites found in a physic nut plantation and its associated spontaneous plants. Mite sampling was monthly conducted in dicotyledonous and monocotyledonous leaves of spontaneous plants as well as in physic nut shrubs over an entire year. In the dry season there was a higher abundance of phytophagous mites (Tenuipalpidae, Tarsonemidae and Tetranychidae) on spontaneous plants than on physic nut shrubs, while predatory mites (Phytoseiidae) showed the opposite pattern. The overall density of mites on spontaneous plants increased with relative humidity and diversity of spontaneous plants. Rainfall was the variable that most influenced the density of mites inhabiting physic nut shrubs. Agroecosystems comprising spontaneous plants associated with crops harbour a rich mite community including species of different trophic levels which potentially benefit natural pest control due to increased diversity and abundance of natural enemies.

RESUMO: O uso de cultivares de soja resistente a insetos-praga é uma alternativa de controle que diminui os custos de produção e não causa desequilíbrio no agroecossistema. Assim, objetivou-se com este trabalho avaliar se diferentes densidades de plantio influenciam a suscetibilidade de cultivares de soja a Cerotoma arcuata Oliver (Coleoptera: Chrysomelidae) no estado do Tocantins. Para tanto, foram conduzidos ensaios de preferência com chance de escolha em laboratório utilizando os cultivares de soja P98Y70, M8766RR e M9144RR. A preferência dos insetos variou em função da cultivar. Os tricomas desempenham papel importante na proteção das plantas ao ataque da C. arcuata, de forma que o cultivar M8766RR apresenta resistência do tipo não-preferência para alimentação deste desfolhador. PALAVRAS-CHAVE: defesas morfológicas, manejo de resistência, relação inseto-planta.

The African oil palm, Elaeis guineensis Jacq., is the second oil producing plant most extensively cultivated worldwide. The American oil palm, Elaeis oleifera (Kunth) Cortés, is a similar species rarely planted for commercial oil production, but often used for the production of hybrids with the African oil palm. The objective of this work was to compare the mite fauna of different genotypes of the African and the American oil palms as well as of their hybrids. In total, three and five genotypes of the African and the American oil palms and two of their hybrids available at an experiment station in the central part of the Brazilian Amazonia (Campo Experimental Rio Urubu, Embrapa Amazônia Ocidental, Rio Preto da Eva, Amazonas State) were evaluated. Samples were collected in the wet (May 2012) and the dry (October, November 2013) seasons. On American oil palms, mite density was much higher in the wet than in the dry season, while on palms of other groups no significant differences were observed between seasons. Phytophagous mites corresponded to 91.1% of all mites found and Eriophyoidea was by far the most abundant group of these mites. Plant damage by this and other mite groups was not noticed. Mites of the family Tenuipalpidae, to which Raoiella indica Hirst belongs, were not found in this study. In previous studies, R. indica was reported to cause severe damage to several plant species. Phytoseiid species richness and diversities were also higher in the American oil palms than on palms of other groups. The phytoseiids Amblyseius perditus Chant & Baker and Iphiseiodes kamahorae De Leon were the most abundant predators, the first almost exclusively on BR 174 and Coari, and the second, on Manicoré genotypes of the American oil palms. Phytoseiid diversity on hybrids was as low as on African oil palm genotypes in the dry season and lower than on other palm groups in the wet season.