Controle de Sitophilus zeamais Mots., 1855 (Col. Curculionidae) em milho pipoca nas fases adulta e imatura com extratos vegetais.

Abstract

Among the pests associated with seeds and grains stored in Brazil, the weevil, Sitophilus zeamais, stands out as one of the main responsible in the fall of the production, due to the losses and damages caused by this insect pest. Based on these considerations and within an ecological alignment, the present work was carried out, aiming to evaluate the efficacy of seven plant extracts, with insecticidal properties, in the control of the insect in the immature phase (egg) and adult insect mortality. The hydroalcoholic extracts were obtained by the cold extraction method by percolation. The work was carried out at the Laboratory of Storage and Processing of Agricultural Products of the DEAg of the UFCG and in the Laboratory of Pharmacotechnics (LF) of the Department of Pharmacy and Biology of CCBS of UEPB, both based in Campina Grande, PB. Initially, the insect multiplication was performed from specimens collected in stored grains. Subsequently, they were applied by the steam method to adult insects contained in plastic containers at the dose established for each treatment (4, 8, 12 and 16 ml). In a second phase, the four best extracts were selected and the two doses that killed the adult insects in the first phase were selected, which were then fed to the weevils previously inoculated in a popcorn mass by the steam method and directly on the seeds , which after homogenates were dried in the shade for 24 hours. In a third step, the two best extracts were applied directly to the seeds of popcorn, containing eggs of S. zeamais, in the dose of 16 ml, for the evaluation of their efficacy on the emergence of the insect after 40 days of installation of the tests. In a fourth experiment, the effect of these same extracts and dose, employed in the previous stage, on the efficacy of the same in the control of S. zeamais and its effects on germination, moisture content and infested seeds were evaluated. It was observed that adult insects of Sitophilus zeamais are also controlled with extracts of Citrus cinensis (98.62%), Cymbopogon citratus (97.87%) and Nicotiana tabacum (96.50% ), at all doses tested and applied by the steam method. The extracts of Nicotiana tabacum and Cymbopogon citratus demonstrated ovicidal action, controlling this immature stage of the weevil in 96.55 and 95.07%, respectively, and that the physiological quality of the seed of popcorn corn was not affected by the extracts during the period of storage.