03259naa a2200325 a 450000100080000000500110000800800410001910000180006024500950007826000090017330000150018249000080019752023830020565000110258865000150259965000120261465000200262665000090264665000100265565000200266565300140268565300110269965300180271065300110272865300170273965300170275670000210277370000230279477301160281714625882006-03-09       2000    bl uuuu     u00u1 u    #d1 aPRANDO, H. F.  aEtological aspects of oryzophagus oryzae (Coleopterabcurculionidae) in water-seeded rice.  c2000  ap.451. v.1  vv.1  aIn most water-seeded rice cultivation in Southern Brazil, the main insect pest is Oryzophagus oryzae. However, there are few works devoted to the etological study of this species. With the purpose of investigating the behavior of this species in water-seed rice cultivation, the present work was conducted in Itajai Experiment Station- EPAGRI-Itajai, SC, Brazil, in the 1997/98 and 1998/99 growing periods. The rice cultivar tested was Epagri 108. The adult was evaluated for feeding and oviposition behaviors. The larvae were observed from egg eclosion up to their introduction into the soil. The survival period of first instar larvae in the absence of food was also estimated. The predatory insects of the first instar. O. oryzae larvae were observed at laboratory. Adults O. oryzae feed lengthwise  among the veins of leaf parenchyma cuticle, leaving whitish stripes on the leaves. The leaf injuries vary from 2 - 40 mm long to about 1 mm wide. The average injured area amounts to 51.24 mm2 per female, and 15.52 mm2 per male, in a 24- hour period. In the water-seeded rice, the adults feed on the seed epicotyl and radicle, injuring 1.06 seedlings/couple/day. They can feed under water and may remain up to 11 days under distilled water. The oviposition takes place on leaf sheaths. The female selects the oviposition site, makes a scission with jaws, rotates 180oC, introduces the ovipositor into the scission and lays one egg at a time into the aerenchyma. After eclosion the larvae remain for 1- 1.5 days feeding on the inside part of the leaf, open circular orifices and leave. They make their way through the water and into the soil by gravity, and then towards the roots. The first instar larvae open galleries inside the roots, while the subsequent instars perforate and cut the roots. They live strictly in aquatic medium as free ectophytic larvae. However, first instar larvae are endophytic having only a short ectophytic stage, that goes from their going out of the leaf up to entering the root. They move slowly, do not present natatory appendices and can only survive in still waters, mud and waterlogged soil. Most predatory insects from first instar larvae , collected on rice plants in the water, belong to at least three species of the Dytiscidae family. One of this species consume in average six larvae of O. oryzae per hour, under laboratory conditions.  aBrazil  aDytiscidae  aInsecta  anatural enemies  arice  aArroz  aInimigo Natural  aBehaviour  aBrasil  aComportamento  aDamage  aInseto praga  aPest insects1 aSOSA-GOMEZ, D.R.1 aROSADO NETO, G. H.  tIn: INTERNATIONAL CONGRESS OF ENTOMOLOGY, 21., 2000, Foz do Iguassu. Abstracts... Londrina: Embrapa Soja, 2000.