Avaliação de injúrias e determinação do nível de dano de Dichelops (Diceraeus) melacanthus (Dallas, 1851) (Heteroptera: Pentatomidae) na cultura do milho (Zea mays L.)

Abstract

The stink bug Diceraeus melacanthus (Dallas, 1851) (Heteroptera: Pentatomidae) is one of the main insect pests of corn, being responsible for lesions in plants in their initial development stages, resulting in productivity losses in the crop. Monitoring the insect population in cultivation areas is necessary to prevent infestations from reaching levels capable of causing economic damage. The objective of this work was to evaluate the damage caused by different levels of adult stink bug infestations in corn crops. The insects came from the laboratory's own rearing, kept at a controlled temperature of 25º ± 2º C, photophase of 12 h and humidity of 70 ± 5%, with a diet consisting of green beans, soybean, sunflower and peanut seeds. Field tests were carried out, and the crop was implemented in February 2022, the second harvest period in the region. The corn seedlings were surrounded by metallic cages covered with voile fabric, so that the insects do not escape, corresponding to 1 square meter with 6 plants per cage. The field experiment was implemented in a randomized block design with six treatments (0, one adult, two adults, four adults, six adults and eight adults), and five replications. The experiment was reproduced in a greenhouse, where only damage was evaluated, following the Bianco scale, with the same treatments and randomized block design. Both in the field and in the greenhouse, the plants were infested at stage V1 and monitored for 14 days, when the cages were removed and the bugs were eliminated, evaluating the plants using the Bianco damage scale. It was observed that as the bug population/m2 increases, there is an increase in the scale of damage and consequent reduction in the quality of the plants. At the end of the crop cycle, the grain productivity of the different treatments was evaluated. From the data obtained, it was possible to assess the level of damage to the crop, established at 0.92 stink bugs/m2 . The results obtained contribute to the definition of the population level of the insect pest that requires its control, avoiding economic damages and the indiscriminate use of insecticides.