Controle econômico do "manhoso", Chalcodermus bimaculatus Fiedler, 1936, na cultura do caupi, Vigna unguiculata (L.) Walp.

Abstract

The present work show the economical control of cowpea curculio, Chalcodermus bimaculatus Fiedler 1936 (coleoptera: curculionidae) in a cowpea field, Vigna unguiculata (L.) Walp. cv. 'Pitiúba' in Fortaleza county, Ceará, Brazil, during the 1993 season. It was adopted the incomplete balanced block design with ten treatments, in which monocrotophos and cyromazine were pulverizated in various application levels. Samples were taken at an 3-4 days interval, based on the growth rhythm of the pods. The date were analized in reIation to quantitative and qualitative aspects of the yield, and evaluated in function to the percentage of seeds depreciation, using as reference the buying price in the businessmarket of Fortaleza. The adequate cowpea curculio control (NAC) was obtained with basis in the benefit/cost relation and profit margin to each treatment. The results were: a) the cowpea curculio damage shows up through the qualitative aspect of the yield, only; b) the economic losses caused by cowpea curculio may reach almost 20% total value of production; c) the adequate cowpea curculio control (NAC) for commercial dried bean is when twenty scars are observed per unit of 10 to 12 cm lenght green pod with monocrotophos at 120 g of a.i/ha; d) cyromazine at 90 g of a.i/ha was not satisfactory against the cowpea curculio, due to high percentage of losses and low benefit/cost relations and profit margin in all treatments used.