Efeito do tratamento de sementes no manejo do Dichelops melacanthus (DALLAS, 1851) (HEMIPTERA: PENTATOMIDAE) na cultura do milho

Abstract

Maize is one of the most produced crops in Brazil and the world. This crop is of vital importance for the livestock production chains (poultry, swine and dairy) in the South of Brazil. The increase in crop productivity occurred due to changes in the planting and management system. These changes triggered the occurrence of pest insects such as Dichelops melacanthus that significantly affect the productive potential of the crop. In this context, the objective of this study was to evaluate the effect of seed treatment with insecticides on the management of D. melacanthus (Dallas, 1851) (Hemiptera: Pentatomidae) in corn. The experimental design used was randomized blocks with six treatments, T1 - imidacloprid (Gaucho ® FS), T2 - thiamethoxam (Cruiser ® 350 FS), T3 - imidacloprid + thiodicarb (CropStar ®), T4 - fipronil (Shelter ®) T5 - bifenthrin + imidacloprid (Rocks®) at the recommended doses of each product and T6 - control (applied distilled water). For each treatment, four replicates were used. One week after the emergence of the plants the cages were placed in the plots, totaling 24 cages in the experiment, each cage being infested with an adult couple of D. melacanthus. The experimental units consisted of voile-type fabric cages having 1 m × 1 m × 0.5 m length, width and height respectively, containing in each cage nine corn plants. The D. melacanthus used in the experiment came from the laboratory kept in the EPAGRI / CEPAF. One week after the first infestation, another adult couple of same specie were introduced per cage. The cages were kept on the plants until 21 DAE (days after emergence), and after removal of the cages, the nine plants that were inside were identified and the damages quantified by scale of note of damage. In addition to the damage score at 21 DAE, spike insertion height, plant height, average number of spikes per plant, number of spikes per area, productivity and weight of one thousand grains were evaluated. The variables that differed between treatments were damage score at 21 DAE, height of spike insertion and weight of one thousand grains. The T6 (control) treatment had the highest average damage at 21 DAE of corn. For the variable ear insertion height the T5 treatment (bifrentrin + imidacloprid) had a higher mean. The treatment T1 (imidacloprid) presented greater weight of a thousand grains. The yield, ear number per plant and ear number per area were not affected by seed treatment.