Application periods against diceraeus (dichelops) melacanthus on maize and their significant response on damage and grain yield in the Brazilian Midwest

Abstract

Diceraeus melacanthus (Dallas, 1851) (Heteroptera: Pentatomidae) remains one of the primary pests in maize nowadays in Brazil, causing significant losses in production. Different insecticide application periods against this pest were performed, and the following parameters were evaluated the plant damage, maize yield and an economic analysis was conducted using these two parameters. The experiment was performed in two growing seasons (2021 and 2022) in a two-factor scheme, with five insecticide application periods: zero (untreated); V1–V3; V1–V3 + V3–V4; V1–V3 + V3–V4 + V4–V6, and V1–V3 + V3–V4 + V4–V6 + V6–V7; and three insecticides: acephate (Perito - 970 g a. i./kg SG - 1,0 kg/ha), thiamethoxam + lambda-cyhalothrin (Engeo Pleno S - 141 + 106 g a. i./L ZC - 0,3 L/ha) and ethiprole (Curbix - 200 g a. i./L SC - 0,75 L/ha). There was a significant difference for the isolated factors of growing season, evaluation stages, application periods and insecticides for the number of plants with damage rating ≥2. Curbix, Engeo Pleno and Perito showed the maximum reduction of damage in maize plants with application periods at V1–V3 + V3–V4 + V4–V6 and V1–V3 + V3–V4 + V4–V6 + V6–V7, presenting 3.2 and 2.9 plants with damage rating ≥2, respectively. Evaluations between the V7 and V8 stages showed a negative correlation with maize yield (Cor = −0.712 at V7 and -0.537 at V8). Regardless of the insecticide used, the V1–V3 + V3–V4 + V4–V6 + V6–V7 application period had the highest productivity, with an average of 4660 kg/ha, differing 681.8 kg/ha and net income of $ 30,3/ha from the uncontrolled plots. Additionally, every 5 days of an application period increased the yield in 178,9 kg/ha or 35 kg/ha daily. Therefore, the use of control tactics from V1–V3 to V6–V7 of maize plants contributes significantly to the reduction of damage, the increase of productivity and a higher net income.