Danos causados pelo percevejo barriga-verde, Dichelops melacanthus (Dallas, 1851) (Hemiptera: Pentatomidae) nas culturas do milho, Zea mays L. e do trigo, Triticum aestivum L.

Abstract

This work had the objective to evaluate wheat and corn yield in the presence of stink bug using different infestation periods of the plants. The experiments were done led in a greenhouse at Embrapa Western Region Agriculture in Dourados, Mato Grosso do Sul State. In the wheat experiment, BR 18 cultivar was sown in pots with a final population of 14 plants/pot. Five densities of the pest population were evaluated (0, 2, 4, 6, and 8 bugs adults/pot) in four different infestation periods (right after plant emergence and after 7, 14, and 21 days of plant emergence). In the corn experiment, Exceller cultivar was sown in pots with a final population of 2 plants/pot, that were infested with 4 bugs adults on five different plants stages (V1 – one leaf; V2 – two leaves; V3 – three leaves; V4 – four leaves; and V5 – five leaves). Each plant on the pot was covered with an iron structure and a tulle net to keep the insect for a period of 15 days for wheat plants and a period of 10 days for corn plants. The experimental design for the wheat experiment was a complete randomized with five replicates in a factorial structure of 5 bug densities and 4 plant stages. The experimental design for the corn experiment was a complete randomized with seven replicates (stink bug/pot). Measurements of dry matter content for the upper plant part, grain yields of corn and wheat, number of ears per pot, ear weight and weight of 100 wheat seeds were submitted to variance analysis and averages compared using Tukey test at 5%. Dry matter content of the upper plant part, number and weight of ears and wheat grain yields were influenced by the different stink bug population levels in at least two of the periods of infestation. Damage intensities of the stink bug on wheat plant were not influenced by the different plant stages. For the corn experiment, dry matter content of the upper plant part was influenced by the stage of development of the plant in which the attack of the bug. Grain yield of corn is influenced by the presence of tummy bug-green when the attack occurs in stages 1, 2, 3, 4 and 5 leaves.