03632naa a2200253 a 450000100080000000500110000800800410001910000200006024500550008026000090013530000110014452028890015565000110304465000170305565000110307265000100308365000090309365300110310265300130311365300160312665300120314270000250315477301990317914617802004-10-15       1999    bl uuuu     u00u1 u    #d1 aOLIVEIRA, L. J.  aManaging insects with concealed habits on soybean.  c1999  ap.647.  aSoybean has been traditionally damaged by defoliator and seed sucking insects, in Brazil. In the last two decades, outbreaks of new groups of insects have been observed. The expansion of the crop to new regions, replacing native hosts, and the insect adaptation to soybeans stand for the continuous growing of insect populations and their damage. The increase in no-tillage cultivation systems and monoculture has favored the change of status of these insects from secondary to primary soybean pests. The effect of broad spectrum insecticides, affecting less intensively the pest occupying concealed ecological niches, as main stems and roots, than is natural enemies, also probably collaborates. These relatively recent pests are hard to control by usual means, and careful behavioral studies have been necessary for their management. Adults of the stem borer gall maker, Sternechus subsignatus Boheman (Col.: Curculionidae), which damages soybean by scraping stems and petioles while females girdle stems to lay eggs inside. As the larvae develop, boring the stems, a gall is formed, where they spend its feeding period Mature larvae hibernate in the soil, up to 10 months, without feeding; pupation also occurs in the soil. S. subsignatus is univoltine, and its life cycle is synchronized with soybean development. Insects are normally concealed during their pre- and post-embryonic stages and frequent insecticide sprayings are necessary, due to its behavior and its long period of adult emergence. S. subsignatus is oligophagous, and its spatial distribution from the site of adult emergence is limited. A complex of white grubs have been observed, destroying soybean secondary roots. The species phyllophaga cuyabana (Moser) (Col.: Melolonthidae) is a native, poliphagous and univoltine insect. Only adults come out the soil for mating, during the night. Larvae feed on soybean roots during the whole development period of the crop; larval diapause occurs after soybean harvesting. From the knowledge of the behavior, various IPM tatics have tested to control S. subsignatus and white grubs. Results indicated that crop rotation, trap crop in stripes (to attract and control adults with insecticides) and earlier or later soybean sowing (to disrupt insect-plant synchrony) have maintained their population below economic threshold levels. The burrower bugs, Scaptocoris castanea Perty and Atarsocoris brachiariae Becker (Hem.: Cydnidae) have increased, recently, specially in the Central Region of Brazil. These insects are poliphagous, sucking roots of cotton, soybean, corn, rice, beans, pasture, as well as weeds, delaying growing or killing plants. Chemical control has not been feasible and cultural practices, as earlier sowing, as well as management and fertilization of soil, may be important IPM tools to minimize the loss of soybean yield due to burrower bugs insects.  aBrazil  apest control  aInseto  aPraga  aSoja  aBrasil  aControle  aPest insect  aSoybean1 aHOFFMANN-CAMPO, C.B.  tIn: WORLD SOYBEAN RESEARCH CONFERENCE, 6., 1999, Chicago. Proceedings: invited and contributed papers and posters. Chicago: University of Illinois / Soybean Research & Development Council, 1999.