Oxicenus maxwelli (Keifer) (Acari: Eriophyidae) danificando a cultura da oliveira, Olea europaea L., no Estado do Rio Grande do Sul Oxicenus maxwelli (Keifer) (Acari: Eriophyidae) damaging olive tree, Olea europaea L., in Rio Grande do Sul State

O micro ácaro da oliveira Oxicenus maxwelli (Keifer, 1939) foi identificado em pomares de oliveira nos municípios de Santana do Livramento, Bagé, Candiota, Pelotas e Rio Grande, RS, nos meses de novembro de 2010 a fevereiro de 2011. A espécie foi encontrada nas faces superior e inferior de folhas jovens, em flores e brotos, onde causa deformações, queda de folhas e flores, diminuição da fotossíntese e superbrotação, prejudicando a produção da planta e a comercialização dos frutos deformados. Este é o primeiro registro da espécie atacando a oliveira no Estado do Rio Grande do Sul.<br>The olive bud mite Oxicenus maxwelli (Keifer, 1939) was identified in olive groves in the municipalities of Santana do Livramento, Bagé, Candiota, Pelotas and Rio Grande, RS in November 2010 to February 2011. The specie was found on the upper surface and under surface of young leaves, flowers and buds where it causes deformities, loss of leaves and flowers, decreased photosynthesis and budding, damaging the plant's production and marketing of deformed fruits. This is the first record of the species attacking the olive tree in the state of Rio Grande do Sul

Isolation and molecular characterization of symbiotic fungus from Acromyrmex ambiguus and Acromyrmex heyeri ants of Rio Grande do Sul State, Brazil

Leaf-cutting ants of the genera Atta and Acromyrmex determine serious agricultural problems and live on symbiosis with Leucoagaricus gongylophorus. The aim of this study is to identify morphological and molecularly, as well as to verify the genotypic variability of the symbiotic fungus cultivated by A. heyeri and A. ambiguus from three different regions of the state of Rio Grande do Sul, Brazil. Fungus gardens were collected and fragments of mycelia were grown in selective medium. Total DNA was extracted and amplification of the ITS region was performed by PCR using universal primers. After DNA sequencing, the chromatograms were assembled and phylogenetic analyzes were performed by the Neighbor-Joining method. A total of six isolates of L. gongylophorus were obtained and their identities were confirmed by molecular analyses. Phylogenetic analysis of the ITS region showed a tree with two distinct groups regarding the fungus isolates from A. heiyeri and A. ambiguous. In this study, it was verified that A. heyeri and A. ambiguous, cultivate the same fungus. Additionally, the molecular marker used in this study showed variations in L. gongylophorus, evidencing two distinct branches in the phylogenetic tree, according to the ant species that cultivate L. gongylophorus. However, other studies involving the inclusion of a great number of isolates of L. gongylophorus, as well as the use of other molecular markers to validate the possible variations in the phylogenetic relationship of this symbiotic fungus are required