Utilização de dioxido de carbono (CO2) com gas fosfina (PH3) no controle de pragas de grãos armazenados




The present work utilized gaseous mixtures of carbon dioxide and phosphine aiming to eliminate all stages of Sitophilus zeamais Motschulsk:y, Sitophilus oryzae Linneus and Rhyzopertha dominica Fabricius. The concentrations of carbon dioxide utilized were 10%, 20%, 30% and 40%, in combination with 100ppm, 200ppm, 400ppm and 600ppm of phosphine. The grains utilized were quality protein maize BR-2121 (for S. zeamais) and wheat BR-lO (for S. oryzae and R. dominica). The exposition periods were 48, 72 and 96 hours. The fumigation chambers were composed by PVC tubes with 30cm height and 25cm diameter, closed with PVC plates and welded with PVC weld. The chambers were composed for gaseous inlet/outlet systems. The treatments, in three repetitions, were constituted for the combination of 4 doses of phosphine and the 4 concentrations of carbon dioxide, totaling 16 composed formulations, 4 carbon dioxide single formulations, 4 phosphine single formulations, and control treatment. The insects were studied in all pre-emergent and adult stages. The S. zeamais showed as the more susceptible insect to formulations. Even the more tolerant stages (eggs, 40 instar larvae, and pupae, where the single formulations don t controlled 100% the infestations), were totally controlled for the more elevated doses of carbon dioxide and phosphine. The S. oryzae showed a more tolerance to gaseous formulations compared to S. zeamais. Only formulations composed by CO2 and 600ppm phosphine controlled eggs. A same behavior were detected in 40 instar larvae. The insect R. dominica showed, in egg stage, great mortality using compounds formulations. The pupae stage showed equal behavior to egg of S. oryzae. This two stages were considered the most resistant to formulations utilized. However, the complete control of this stages using compound formulations were obtained using the time expositions studied, showing the efficiency of this method. In a1l treatments where carbon dioxide associated to phosphine has used detected a better control of the insects, showing a synergism between this two gases.


trigo - doenças e pragas - controle sitophilus zeamais fosfina dioxido de carbono

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