Abstract
We examined the interaction between phytophagous, predaceous mites in Valencia orange (Citrus sinensis) orchards at different altitudes in the Taquari Valley, Rio Grande do Sul, Brazil. Mites were sampled monthly from February 2005 to January 2006 in three citrus agroecosystems: Arvorezinha, Encantado and Taquari. For each agroecosystem, twelve leaves were taken from each of ten citrus plants, plus ten fruits and leaves from five associated plants found in citrus orchards. Predaceous species considered important were Agistemus floridanus Gonzalez (Stigmaeidae), Euseius ho (De Leon) (Phytoseiidae) and Pronematus anconai Baker (Iolinidae). Other predators found were Iphiseiodes zuluagai Denmark & Muma (Phytoseiidae), in Taquari and Homeopronematus sp. (Iolinidae), Parapronematus sp. (Iolinidae), Neoseiulus tunus (DeLeon) (Phytoseiidae) and Typhlodromips cananeiensis Gondim Jr. & Moraes (Phytoseiidae), in Encantado. The most frequent phytophagous mites were Brevipalpus phoenicis (Geijskes) (Tenuipalpidae), Lorryia formosa Cooreman (Tydeidae), Lorryia sp. (Tydeidae), Tegolophus brunneus Flechtmann (Eriophyidae) and Tetranychus mexicanus (McGregor) (Tetranychidae). Other phytophages were Eutetranychus banksi (McGregor) (Tetranychidae) in Taquari and Phyllocoptruta oleivora (Ashmead) (Eriophyidae) in Arvorezinha. The predator A. floridanus had the strongest correlation to the presence of common phytophagous mites, followed by P. anconai that seemed to be associated with eriophyid and tetranychid mites. The least number of predators occurred in Arvorezinha, where mowing and phytosanitary treatments were frequent. The associated plants Thelypteris dentata (Forssk.) E.P. St. John and Solidago chilensis Meyen had the largest abundance of predatory mites. However, Ageratum conyzoides L. had the highest diversity of predatory mites.