Efeitos de extratos vegetais com relação à mortalidade do caruncho (Sitophilus zeamais L.) e a qualidade fisiológica de sementes de milho armazenadas.

Abstract

The plague presence in stored corn is one of the factors limits the maintenance of the viability of those seeds, being responsible one of the main ones in the fali of the producrion, due to the great number of losses and damages in the stored seeds. With base in those considerations, this work search alternatives in the control of the Sitophilus zeamais, in the adult phase and of egg by means of the employment of six vegetable species for containing in its composition substances with insecticide properties and for the extracts of those plants to configure in an alternative to tiie commercial chemical products with quite interesting ecological advantages, due to the low aggressiveness to the atmosphere and the man. The work was driven in the period august/2001 to may/2003, in the Department of Agricultural Engineering of UFCG. The extracts were obtained by the extraction method to cold for percolação. The experimental lineation used in the biopractices was it entirely casualty with the treatments distributed in outline factorial, except in the third stage where the distribution factorial was not used, being used being used in the first stage, regression in the variance analysis for the factors studied in agreement with the number that you/they carne each rehearsal (extracts, doses, application form and storage period) and the variables of answers (adults' mortality, egg apprenticeship, infested seeds, loss of the weight, viability of seeds and humidity text). With base in the results of biopractices each, it is had that the application of the extracts directly on the seeds the method that best controlled Sitophilus zeamais present in the mass of seeds was, being the extracts of Calopogonium caeruleum and Ruta graveolens the most efficient in the control of the S. zeamais, so much in the adult phase as of egg and the best dose was the one of 12 ml. The physiologic quality of the corn seed was not affected by the application of the extracts, being these considered effective in the maintenance of the physiologic quality of the seeds during the 90 days of storage and the extracts of Calopogonium caeruleum and Ruta graveolens that acted with larger efficiency in killing the insects, they possess chemical groups: alkaloids, flavonóides and tannins, with insecticide properties tiiat justify that action.