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RESUMO – O comportamento produtivo do milho na presenca de diferentes niveis populacionais de insetos adultos do percevejo Dichelops melacanthus em diferentes estadios de desenvolvimento da planta foi determinado em casa de vegetacao e no campo com o objetivo de estimar o seu nivel de dano economico (NDE). A massa seca da parte aerea e o rendimento de graos foram significativamente reduzidos na presenca do percevejo, independente dos estadios de desenvolvimento da planta (V1 a V3). Em campo, utilizando-se gaiolas e infestando as plantas no estadio V1 durante 10 dias consecutivos, nao foram observadas diferencas no peso de 100 graos em relacao as densidades populacionais utilizadas. No entanto, houve reducao significativa no rendimento de graos com o aumento da densidade populacional do percevejo. Em funcao dos resultados obtidos, e possivel estimar que o NDE para D. melacanthus na cultura do milho e de 0,8 percevejo/m2, densidade populacional na qual o controle da praga e justificado economicamente. Palavras – chave: Dichelops melacanthus, estadio de desenvolvimento da planta, rendimento de graos, densidade populacional, injuria. DAMAGE AND ECONOMIC THRESHOLD OF THE STINK BUG ON CORN CROP ABSTRACT - This work aimed to evaluate the effect of the population level and infestation time of D. melacanthus in corn, as well as to estimate its economic threshold level (ET). The damage experiment was carried out under greenhouse. Corn plants were infested with 4 adult bugs on five different plant stages for a period of 10 days. Shoot dry mass content was significantly reduced by the presence of the stinkbug at all stages and grain yield was affected by the stinkbug when infestations occurred in the stages V1, V2 and V3. In the economic damage threshold level experiment, corn plants at one leaf stage were submitted to different infestation levels of stink bug for a period of 10 days, inside cages in the field. The weight of 100 grains was not significantly affected by populations of the stink bug; however, grain yield was significantly reduced when the population density of the bug in cages increased. The economic threshold level of the D. melacanthus for corn was 0.8 stink bug/m2. Key words: Dichelops melacanthus, plant stage of the development, yield, population density, injury. |
