ABSTRACT. Spider cornrn unities (Araneae) on rubber tree (Hevea brasiliensis Muell. Arg.) plantations in São Paulo State, Brazil. The spider fauna co mpositi on of three rubber tree co mmercial plantations in the Northwest part of São Paulo State, Brazil , was characteri zed for both canopy and li tter strata. On seven occasions fram April 2000 to October 200 I, samples were taken by beating sheet and hand capture, res ulting in a total of 946 individuaIs, belonging to 24 fam ilies and 11 9 species. The most co mmon speci es were ltalaman santamaria Brescovil , 1997 and Teudis sp. (Anyphaenidae), Caslianeira sp. and Falconina aff. gracilis (Corinnidae), Paracleocnemis sp. (Philodramidae), lbo fypora nga ,wideae Mello-Leitão, 1944 (Pholcidae) , Chira spinipes (Taczanowiski , 1871 ) and Rudra sp. (Salticidae), A chaearanea hirla (Taczanowiski , 1873) and Coleosom.a jloridanum (Banks, 1900) (Theridiidae) and Coeldia sp. (Titanoecidae). Anyphaenidae, Theridi idae and Salticidae were the mosl abundant fami lies in the canopy, while Pholcidae and Co rinnidae in the litter. Spider abundance was found to be, in general , positively correlated to the litter volume and density of branches in the trees. The use of acaricides and insecticides for one plantation resulted in a dec rease in spider abundance for both strata. Abundance values among the sampl es suggest thal lhe canopy sp ider abundance decreases with lhe loss of leaves in lhe dry seaso n. Simultaneously, li tter spider abundance increased in lhi s season, because of the increase in lilter volume. The moSl aclive canopy spiders, like runners and stalkers, should be in vestigated For their potenlial as pest contraI agents. KEY WORDS . Spiders, Hevea brasiliensis, guild s, biodiversity, peslicides Aranhas co mpõ e m um dos gru pos de predadores nativos mais abundantes na maioria dos habitats terrestres, incl u indo os agríco las. Como inimigos naturais de artrópodes , as aranhas podem contr ibuir n a reg ul ação das pop ul ações de in se tos e de ácaros fitófagos, prejudiciais para cultivos comerciais. Por esta razão, as a ranhas têm sido ativamente preservadas em áreas agríco las da China (ZHAO 1993 apud MARC & CANARD 1997).Estudos sobre biodiversidade e ecolog ia básica desses p redadores em agroecossistemas são fundamentais para uma utilização m ais racional do ambiente pe lo homem. Levantamentos conduzidos em áreas agrícolas têm revelado alta d iversidade de aranhas (RI NALDI & FORTI 1997), o que afasta a idéia freqüente de q u e os sistemas agrícolas são sim plificados quanto à araneofauna.