Manejo de Dalbulus maidis com o uso combinado de inseticidas químicos e biológicos em Zea mays

Abstract

Maize (Zea mays) stands out among the main agricultural crops in Brazil, playing a fundamental role in human and animal nutrition. However, crop productivity has been compromised by the corn leafhopper, Dalbulus maidis (Hemiptera: Cicadellidae), an insect vector of pathogens associated with the Corn Stunt Disease Complex. The losses resulting from this interaction between vector and pathogens reinforce the need to adopt efficient management strategies aimed at controlling the pest and reducing crop damage. Therefore, the present study aimed to evaluate the effects of phytosanitary management, involving the use of chemical insecticides alone and the association between chemical and biological control, on the severity of the corn stunt complex and maize productivity in different cultivation environments in the state of Paraná, Brazil. The experiment conducted in Pato Branco was carried out during the 2025 second crop season (“safrinha”), using a randomized block design with the hybrid Agroeste 1850 PRO4 and three phytosanitary management strategies. In this experiment, population monitoring of the corn leafhopper was performed using sticky traps, visual assessment of stunt severity was carried out, and grain yield corrected to 13% moisture was determined. In parallel, network trials were established in the municipalities of Londrina, Campo Mourão, and Assaí, in a 3 × 3 factorial arrangement, combining three hybrids with different levels of tolerance to the corn stunt complex and three phytosanitary management strategies. Disease severity and productivity were evaluated in these trials. The data obtained were subjected to analysis of variance and statistical modeling using R software, including correlation and regression analyses to investigate the relationship between stunt severity and maize productive performance. Stunt severity and the population fluctuation of D. maidis were significantly reduced in treatments with chemical management alone and with the combined use of chemical and biological control. However, in the experiment conducted in Pato Branco, grain yield did not differ significantly among treatments, a result mainly attributed to the occurrence of frost during the crop cycle, which reduced yield potential and masked the effects of management. In the network trials, productivity and stunt severity were strongly influenced by the environment, with Londrina characterized by higher disease pressure, Campo Mourão by low severity and high yields, and Assaí showing intermediate performance. Stunt severity was predominantly determined by genetic material and by the genotype × environment interaction. The integrated analysis revealed a strong negative correlation between stunt severity and productivity, indicating progressive yield losses with increasing disease intensity. It is concluded that management of the insect vector is essential to reduce stunt severity and stabilize the population dynamics of the corn leafhopper; however, its effects on productivity depend on the interaction among environment, climate, and the genetic potential of the hybrids.